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Hypertriglyceridemia: Evaluation and Treatment Guideline

Reporter and Curator: Dr. Sudipta Saha, Ph.D.

 

Severe and very severe hypertriglyceridemia increase the risk for pancreatitis, whereas mild or moderate hypertriglyceridemia may be a risk factor for cardiovascular disease. Individuals found to have any elevation of fasting triglycerides should be evaluated for secondary causes of hyperlipidemia including endocrine conditions and medications. Patients with primary hypertriglyceridemia must be assessed for other cardiovascular risk factors, such as central obesity, hypertension, abnormalities of glucose metabolism, and liver dysfunction. The aim of this study was to develop clinical practice guidelines on hypertriglyceridemia.

The diagnosis of hypertriglyceridemia should be based on fasting levels, that mild and moderate hypertriglyceridemia (triglycerides of 150–999 mg/dl) be diagnosed to aid in the evaluation of cardiovascular risk, and that severe and very severe hypertriglyceridemia (triglycerides of >1000 mg/dl) be considered a risk for pancreatitis. The patients with hypertriglyceridemia must be evaluated for secondary causes of hyperlipidemia and that subjects with primary hypertriglyceridemia be evaluated for family history of dyslipidemia and cardiovascular disease.

The treatment goal in patients with moderate hypertriglyceridemia should be a non-high-density lipoprotein cholesterol level in agreement with National Cholesterol Education Program Adult Treatment Panel guidelines. The initial treatment should be lifestyle therapy; a combination of diet modification, physical activity and drug therapy may also be considered. In patients with severe or very severe hypertriglyceridemia, a fibrate can be used as a first-line agent for reduction of triglycerides in patients at risk for triglyceride-induced pancreatitis.

Three drug classes (fibrates, niacin, n-3 fatty acids) alone or in combination with statins may be considered as treatment options in patients with moderate to severe triglyceride levels. Statins are not be used as monotherapy for severe or very severe hypertriglyceridemia. However, statins may be useful for the treatment of moderate hypertriglyceridemia when indicated to modify cardiovascular risk.

 

References:

 

https://www.medpagetoday.com/clinical-connection/cardio-endo/77242?xid=NL_CardioEndoConnection_2019-01-21

https://www.ncbi.nlm.nih.gov/pubmed/19307519

https://www.ncbi.nlm.nih.gov/pubmed/23009776

https://www.ncbi.nlm.nih.gov/pubmed/6827992

https://www.ncbi.nlm.nih.gov/pubmed/22463676

https://www.ncbi.nlm.nih.gov/pubmed/17635890

 

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Reversing Heart Disease: Combination of PCSK9 Inhibitors and Statins – Opinion by Steven Nissen, MD, Chairman of Cardiovascular Medicine at Cleveland Clinic

Reporter: Aviva Lev-Ari, PhD, RN

UPDATED on 2/25/2019
https://www.medpagetoday.com/cardiology/prevention/78202?xid=nl_mpt_SRCardiology_2019-02-25&eun=g99985d0r&utm_source=Sailthru&utm_medium=email&utm_campaign=CardioUpdate_022519&utm_term=NL_Spec_Cardiology_Update_Active

While nearly 10% of middle-age adults in China have high risk for cardiovascular disease, only 0.6% of these high-risk individuals use statins and 2.4% take aspirin, a national screening project reported in the Annals of Internal Medicine.

UPDATED on 5/5/2017

Europeans Mull PCSK9i Post-FOURIER Fallout on Clinical Practice

Patrice Wendling, May 04, 2017

But it was panelist Dr Stephen Nicholls (University of Adelaide, Australia) who took aim at the elephant in the packed auditorium. At an annual cost of about $14,100 for evolocumab and $14,600 for alirocumab (Praluent, Sanofi/Regeneron), the important question facing cardiologists is who will be eligible for these drugs “in a world where we can’t just write a scrip for every FOURIER-type patient; we won’t be allowed to.”

He suggested initially this will include patients with familial hypercholesterolemia and only those with established atherosclerotic CVD whose LDL-C remains unacceptably high despite therapy. Future FOURIER subanalyses may define other eligible high-risk groups.

http://www.medscape.com/viewarticle/879523?nlid=114642_3802&src=WNL_mdplsnews_170505_mscpedit_card&uac=93761AJ&spon=2&impID=1342003&faf=1#vp_2

 

 

UPDATED on 3/14/2017

PCSK9 Inhibitor Access Snarled in Red Tape, Rejections

Patrice Wendling, March 21, 2017

To determine whether this experience is happening nationwide, Navar and colleagues examined first PCSK9 prescriptions in 45,029 patients (median age 66 years; 51% female) between August 1, 2015 and July 31, 2016 in the Symphony Health Solutions database, which covers 90% of retail, 70% of specialty, and 60% of mail-order pharmacies in the US.

Nearly half (48%) of prescribers were cardiologists, and 37% were general practitioners. Most patients (52%) had government insurance, typically Medicare, and 40% had commercial insurance.

In the first 24 hours after being submitted to the pharmacy, 79.2% of prescriptions were rejected. Ultimately, 52.8% of all PCSK9 prescriptions were rejected.

Of special note, 34.7% of prescriptions for the pricy lipid-lowering drugs were abandoned at the pharmacy.

http://www.medscape.com/viewarticle/877515?nlid=113592_3802&src=WNL_mdplsnews_170324_mscpedit_card&uac=93761AJ&spon=2&impID=1314983&faf=1

 

How 2 Drugs Lower Cholesterol Remarkably — and Reverse Heart Disease

Study shows promise for combination of newer drug and statins

How 2 Drugs Lower Cholesterol Remarkably --- and Reverse Heart Disease

Newer cholesterol-lowering drugs combined with more conventional medicine reduces bad cholesterol to incredibly low levels, a new study shows. Perhaps even more important, the combination also reduces the heart-attack-inducing plaque that forms inside the arteries, the study says.

The study was led by cardiologist Steven Nissen, MD, Chairman of Cardiovascular Medicine at Cleveland Clinic. Results appeared recently in the Journal of the American Medical Association (JAMA).

The study looked at the use of a drug called evolocumab by people who took statins to lower the amount of LDL, or bad, cholesterol in their blood. Evolocumab is a drug called a PCSK9 inhibitor. This is a newer kind of medicine that can make LDL cholesterol levels plummet.

The people who took statins and evolocumab had greater reductions in atherosclerosis compared with people who took statins and a placebo.  Atherosclerosis is  a disease in which plaque builds up inside your arteries.  The condition can lead to serious problems, including heart attack, stroke, or even death.

The results are an intriguing indicator — rather than definite proof — that evolocumab may have benefit for patients taking statins, Dr. Nissen says. Researchers are still awaiting the results of large clinical trials investigating whether evolocumab is safe and will prevent heart attack, stroke or death. The first results of these studies are expected in April 2017.

Special ultrasound

In the study, researchers treated for 18 months 968 high-risk people who had extremely high levels of blood cholesterol.

Participants were randomly assigned to take either a statin and a placebo, or a statin and evolocumab.

Researchers monitored the participants’ cholesterol levels. They also used a special ultrasound probe to measure the amount of plaque in their arteries at the beginning and the end of the study. 

“We were able to show that getting the bad cholesterol levels down to really low levels, down to the 20s and 30s, can actually remove plaque from the coronary arteries,” Dr. Nissen says. “This going to levels that we’ve never been able to achieve before.”           

Low cholesterol, less plaque

Results show the group treated with statins and a placebo reduced their LDL cholesterol levels to 93 on average. At the same time, the group treated with the combination of the statin plus evolocumab got down to an average bad cholesterol level of 36.6.

“No one’s ever reached levels that low in a clinical trial,” Dr. Nissen says.

Participants who took evolocumab also had less plaque in their arteries at the end of the study — essentially reversing their heart disease.

“We, for the first time now, have shown that this new class of drugs, the PCSK9 inhibitors, has a favorable effect on the development of plaques on the coronary artery and can actually regress those plaques,” Dr. Nissen says. “And it turns out about two-thirds of patients actually had less plaque at the end of 18 months than they started with.” 

PCSK9 inhibitors, which are expensive, are not for everybody, Dr. Nissen says. Currently, the drug is used in addition to statins for the highest-risk patients with particularly high cholesterol.

SOURCE

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Diet and Cholesterol

Writer and Curator: Larry H. Bernstein, MD, FCAP 

 

Introduction

We are all familiar with the conundrum of diet and cholesterol.  As previously described, cholesterol is made by the liver. It is the backbone for the synthesis of sex hormones, corticosteroids, bile, and vitamin D. It is also under regulatory control, and that is not fully worked out, but it has health consequences. The liver is a synthetic organ that is involved with glycolysis, gluconeogenesis, cholesterol synthesis, and unlike the heart and skeletal muscles – which are energy transducers – the liver is anabolic, largely dependent on NADPH.  The mitochondria, which are associated with aerobic metabolism, respiration, are also rich in the liver.  The other part of this story is the utilization of lipids synthesized by the liver in the vascular endothelium.  The vascular endothelium takes up and utilizes/transforms cholesterol, which is involved in the degenerative development of pathogenic plaque.  Plaque is associated with vascular rigidity, rupture and hemorrhage, essential in myocardial inmfarction. What about steroid hormones?  There is some evidence that sex hormone differences may be a factor in coronary vascular disease and cardiac dysfunction.  The evidence that exercise is beneficial is well established, but acute coronary events can occur during exercise.  WE need food, and food is at the center of the discussion – diet and cholesterol.  The utilization of food varies regionally, and is dependent on habitat.  But it is also strongly influence by culture.  We explore this further in what follows.

A high fat, high cholesterol diet leads to changes in metabolite patterns in pigs – A metabolomic study

Jianghao Sun, Maria Monagas, Saebyeol Jang, Aleksey Molokin, et al.
Food Chemistry 173 (2015) 171–178
http://dx.doi.org/10.1016/j.foodchem.2014.09.161

Non-targeted metabolite profiling can identify biological markers of dietary exposure that lead to a better understanding of interactions between diet and health. In this study, pigs were used as an animal model to discover changes in metabolic profiles between regular basal and high fat/high cholesterol diets. Extracts of plasma, fecal and urine samples from pigs fed high fat or basal regular diets for 11 weeks were analysed using ultra-high performance liquid chromatography with high-resolution mass spectrometry (UHPLC–HRMS) and chemometric analysis. Cloud plots from XCMS online were used for class separation of the most discriminatory metabolites. The major metabolites contributing to the discrimination were identified as bile acids (BAs), lipid metabolites, fatty acids, amino acids and phosphatidic acid (PAs), phosphatidylglycerol (PGs), glycerophospholipids (PI), phosphatidylcholines (PCs) and tripeptides. These results suggest the developed approach can be used to identify biomarkers associated with specific feeding diets and possible metabolic disorders related to diet.

Nutritional metabolomics is a rapidly developing sub-branch of metabolomics, used to profile small-molecules to support integration of diet and nutrition in complex bio-systems research. Recently, the concept of ‘‘food metabolome’’ was introduced and defined as all metabolites derived from food products. Chemical components in foods are absorbed either directly or after digestion, undergo extensive metabolic modification in the gastrointestinal tract and liver and then appear in the urine and feces as final metabolic products. It is well known that diet has a close relationship with the long-term health and well-being of individuals. Hence, investigation of the ‘‘food metabolome’’ in biological samples, after feeding specific diets, has the potential to give objective information about the short- and long-term dietary intake of individuals, and to identify potential biomarkers of certain dietary patterns. Previous studies have identified potential biomarkers after consumption of specific fruits, vegetables, cocoa, and juices. More metabolites were revealed by using metabolomic approaches compared with the detection of pre-defined chemicals found in those foods.

Eating a high-fat and high cholesterol diet is strongly associated with conditions of obesity, diabetes and metabolic syndrome, that are increasingly recognized as worldwide health concerns. For example, a high fat diet is a major risk factor for childhood obesity, cardiovascular diseases and hyperlipidemia. Little is known on the extent to which changes in nutrient content of the human diet elicit changes in metabolic profiles. There are several reports of metabolomic profiling studies on plasma, serum, urine and liver from high fat-diet induced obese mice, rats and humans. Several potential biomarkers of obesity and related diseases, including lysophosphatidylcholines (lysoPCs), fatty acids and branched-amino acids (BCAAs) have been reported.

To model the metabolite response to diet in humans, pigs were fed a high fat diet for 11 weeks and the metabolite profiles in plasma, urine and feces were analyzed. Non-targeted ultra high performance liquid chromatography tandem with high resolution mass spectrometry (UHPLC–MS) was utilized for metabolomics profiling. Bile acids (BAs), lipid metabolites, fatty acids, amino acids and phosphatidic acid (PAs), phosphatidylglycerol (PGs), glycerophospholipids (PI), phosphatidylcholines (PCs), tripeptides and isoflavone conjugates were found to be the final dietary metabolites that differentiated pigs fed a high-fat and high cholesterol diet versus a basal diet. The results of this study illustrate the capacity of this metabolomic profiling approach to identify new metabolites and to recognize different metabolic patterns associated with diet.

Body weight, cholesterol and triglycerides were measured for all the pigs studied. There was no significant body weight gain between pigs fed diet A and diet B after 11 weeks of treatment. The serum cholesterol and triglyceride levels were significantly higher in pigs fed with diet B compared with the control group at the end of experiment.

Plasma, urine and fecal samples were analyzed in both positive and negative ionization mode. To obtain reliable and high-quality metabolomic data, a pooled sample was used as a quality control (QC) sample to monitor the run. The QC sample (a composite of equal volume from 10 real samples) was processed as real samples and placed in the sample queue to monitor the stability of the system. All the samples were submitted in random for analysis. The quantitative variation of the ion features across the QC samples was less than 15%. The ion features from each possible metabolite were annotated by XCMS online to confirm the possible fragment ions, isotopic ions and possible adduct ions. The reproducibility of the chromatography was determined by the retention time variation profiles that were generated by XCMS. The retention time deviation was less than 0.3 min for plasma samples, less than 0.3 min for fecal samples, and less than 0.2 min for urine samples, respectively. On the basis of these results of data quality assessment, the differences between the test samples from different pigs proved more likely to reflect varied metabolite profiles rather than analytical variation. The multivariate analysis results from the QC sample showed the deviation of the analytical system was acceptable.
Good separation can be observed between pigs on the two diets, which is also reflected in the goodness of prediction (Q2), of 0.64 using data from the positive ionization mode. For negative ionization mode data, better separation appears with a Q2of 0.73.

Cloud plot is a new multidimensional data visualization method for global metabolomic data (Patti et al., 2013). Data characteristics, such as the p-value, fold change, retention time, mass-to-charge ratio and signal intensity of features, can be presented simultaneously using the cloud plot. In this study, the cloud plot was used to illustrate the ion features causing the group separation. In Fig. 2 and 82 features with p < 0.05 and fold change >2, including visualisation of the p-value, the directional fold change, the retention time and the mass to charge ratio of features, are shown. Also, the total ion chromato-grams for each sample were shown. The upper panel in (2A) shows the chromatograms of plasma samples from pigs fed the high fat diet, while the lower panel shows the chromatograms of samples from pigs fed the regular diet. Features whose intensity is increased are shown in green, whereas features whose intensity is decreased are shown in pink (2A). The size of each bubble corresponds to the log fold change of the feature: the larger the bubble, the larger the fold changes. The statistical significance of the fold change, as calculated by a Welch t-test with unequal variances, is represented by the intensity of the feature’s color where features with low p-values are brighter compared to features with high p-values. The Y coordinate for each feature corresponds to the mass-to-charge ratio of the compound, as determined by mass spectrometry. Each feature is also color coded, such as features that are shown with a black outline have database hits in METLIN, whereas features shown without a black outline do not have any database hits.

From the cloud plot (Fig. 2A), 82 discriminating ion features from positive data and 48 discriminating ions features from negative data were considered as of great importance for class separation. After filtering out the fragment ions, isotope annotations, and adduct ions, thirty-one metabolites were tentatively assigned using a Metlin library search (Table S4).

Among the assigned metabolites detected, five of the highest abundant metabolites were identified as bile acid and bile acid conjugates (Fig. 2B). This series of compounds shared the following characteristics; the unconjugated bile acids showed [M-H] ion as base peak in the negative mode.

The characteristic consistent with bile acid hyodeoxycholic acid (HDCA) was confirmed with a reference standard. For the conjugated bile acids (usually with glycine and taurine), the [M-H] and [M+H]+ are always observed as the base peaks. For example, the ion feature m/z 448.3065 at 21.18 min was identified as chenodeoxycholic acid glycine conjugate. The neutral loss of 62 amu (H2O + CO2) was considered as a characteristic fragmentation pathway for bile acid glycine conjugates. This above mentioned characteristic can easily identify a series of bile acids compounds. The five metabolite ions detected in plasma were significantly different between pigs fed the high fat diet (Fig. 2B, red bars) and regular diet (Fig. 2B, blue bars) for 11 weeks, and were identified as chenodeoxycholic acid glycine conjugate, tauroursodeoxycholic acid, hyodeoxycholic acid, deoxycholic acid glycine conjugate and glycocholic acid; chenodeoxycholic acid glycine and hyodeoxycholic acid.

Figures 1-4 , not shown.
Fig 1. The PCA score plot of plasma (A) (+)ESI data with all the ion features; (B) (+)ESI data with selected ion features; (C) (-)ESI data with all ion features; (D) (-)ESI data with selected ion features. Samples were taken from pigs fed diet A (BS, blue) and diet B (HF, red). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Fig 2. Cloud plot showing 82 discriminatory ion features (negative ion data) in plasma, and (B) box-plot of data set of the five most abundant bile acids identified in plasma (negative ion data) samples.

Fig. 3. PCA score plot of fecal samples from pigs fed diet A (BS, blue) and diet B (HF, red) (A) week 0, (B) week 2, (C) week 4 (D) week 6, (E) week 11 for distal samples (F) week 11 for proximal colon samples. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Fig. 4. PCA and PLS-DA score plot of urine samples from (+)ESI-data (A and C) and (-)ESI-data (B and D) taken at the end of the study (week 11) from pigs fed diet A (BS, blue) and diet B (HF, red). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Plasma, fecal and urine metabolites from pigs fed either a high fat or regular diet were investigated using a UHPLC–HRMS based metabolomic approach. Their metabolic profiles were compared by multivariate statistical analysis.
Diet is logically believed to have a close relationship with metabolic profiles. Feeding a high fat and high cholesterol diet to pigs for 11 weeks resulted in
an increase in bile acids and their derivatives in plasma, fecal and urine samples, though at this stage, there was no significant weight gain observed.

In a previous study, a significantly higher level of muricholic acid, but not cholic acid, was found in pigs fed a high fat diet. The gut microbiota of these pigs were altered by diet and considered to regulate bile acid metabolism by reducing the levels of tauro-beta-muricholic acid. In our study, the unconjugated bile acids, hyodeoxycholic acid and deoxycholic acid were found to be significantly higher in the fecal samples of pigs fed a high-fat diet.

Chenodeoxycholic acid glycine was 8.6 times higher in pigs fed a high fat and high cholesterol diet compared to those fed a regular diet. These results confirm that feeding a high fat and high cholesterol diet leads to a changing metabolomic pattern over time, represented by excretion of certain bile acids in the feces. We also found that several metabolites associated with lipid metabolism were increased in the feces of pigs fed the high-fat diet. Feeding the high fat diet to pigs for 11 weeks did not induce any overt expression of disease, except for significantly higher levels of circulating cholesterol and triglycerides in the blood. It is likely, however, that longer periods of feeding would increase expression of metabolic syndrome disorders and features of cardiovascular disease in pigs, as have been previously demonstrated. Products of lipid metabolism that changed early in the dietary treatment could be useful as biomarkers. This may be important because the composition of the fats in the diet, used in this study, was complex and from multiple sources including lard, soybean oil and coconut oil.

In summary, a number of metabolite differences were detected in the plasma, urine and feces of pigs fed a high fat and high cholesterol diet versus a regular diet that significantly increased over time. PCA showed a clear separation of metabolites in all biological samples tested from pigs fed the different diets. This methodology could be used to associate metabolic profiles with early markers of disease expression or the responsiveness of metabolic profiles to alterations in the diet. The ability to identify metabolites from bio-fluids, feces, and tissues that change with alterations in the diet has the potential to identify new biomarkers and to better understand mechanisms related to diet and health.

Amino acid, mineral, and polyphenolic profiles of black vinegar, and its lipid lowering and antioxidant effects in vivo

Chung-Hsi Chou, Cheng-Wei Liu, Deng-Jye Yang, Yi-Hsieng S Wuf, Yi-Chen Chen
Food Chemistry 168 (2015) 63–69
http://dx.doi.org/10.1016/j.foodchem.2014.07.035

Black vinegar (BV) contains abundant essential and hydrophobic amino acids, and polyphenolic contents, especially catechin and chlorogenic acid via chemical analyses. K and Mg are the major minerals in BV, and Ca, Fe, Mn, and Se are also measured. After a 9-week experiment, high-fat/cholesterol-diet (HFCD) fed hamsters had higher (p < 0.05) weight gains, relative visceral-fat sizes, serum/liver lipids, and serum cardiac indices than low-fat/cholesterol diet (LFCD) fed ones, but BV supplementation decreased (p < 0.05) them which may resulted from the higher (p < 0.05) fecal TAG and TC contents. Serum ALT value, and hepatic thiobarbituric acid reactive substances (TBARS), and hepatic TNF-α and IL-1β contents in HFCD-fed hamsters were reduced (p < 0.05) by supplementing BV due to increased (p < 0.05) hepatic glutathione (GSH) and trolox equivalent antioxidant capacity (TEAC) levels, and catalase (CAT) and glutathione peroxidase (GPx) activities. Taken together, the component profiles of BV contributed the lipid lowering and antioxidant effects on HFCD fed hamsters.

World Health Organization (WHO) reported that more than 1.4 billion adults were overweight (WHO, 2013). As we know, imbalanced fat or excess energy intake is one of the most important environmental factors resulted in not only increased serum/liver lipids but also oxidative stress, further leading cardiovascular disorders and inflammatory responses. Food scientists strive to improve serum lipid profile and increase serum antioxidant capacity via  medical foods or functional supplementation.

Vinegar is not only used as an acidic seasoning but also is shown to have some beneficial effects, such as digestive, appetite stimulation, antioxidant, exhaustion recovering effects, lipid lowering effects, and regulations of blood pressure. Polyphenols exist in several food categories, such as vegetable, fruits, tea, wine, juice, and vinegar that have effects against lipid peroxidation, hypertension, hyperlipidemia, inflammation, DNA damage, and. Black vinegar (BV) (Kurosu) is produced from unpolished rice with rice germ and bran through a stationary surface fermentation and contains higher amounts of amino acids and organic acids than other vinegars. Black vinegar is also characterised as a health food rather than only an acidic seasoning because it was reported to own a DPPH radical scavenging ability and decrease the adipocyte size in rat models. Moreover, the extract of BV shows the highest radical scavenging activity in a DPPH radical system than rice, grain, apple, and wine vinegars. The extract suppresses increased lipid peroxidation in mouse skin treated with 12-o-tetradecanoylphorbol-13-acetate.

This study focused on the nutritional compositions in BV, and the in-vivo lipid lowering and antioxidant effects. First, the amino acid, mineral, and polyphenolic profile of BV were identified. Hypolipidemic hamsters induced by a high-fat/cholesterol diet (HFCD) were orally administered with different doses of BV. Serum lipid profile and liver damage indices liver and fecal lipid contents, as well as hepatic antioxidant capacities [thiobarbituric acid reactive substances (TBARS), glutathione (GSH), trolox equivalent antioxidant capacity (TEAC), and activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx)] and hepatic cytokine levels were assayed to demonstrated physiological functions of BV.

Higher serum AST, ALT, and free fatty acids, as well as hepatic cholesterol, triacylglycerol, MDA, hydroperoxide, and cytokine (IL-1β and TNF-α) levels were easily observed in a high-fat-consumption rodent. Several reports indicated some amino acids antioxidant activities in vitro and in vivo. Acidic amino acids, such as Asp and Glu and hydrophobic amino acids, such as Ile, Leu, and Val display high antioxidant properties. Recently, an in vivo study indicated that a pepsin hydrolyzation significantly enhanced Asp, Glu, Leu, and Val contents in chicken livers; meanwhile, chicken-liver hydrolysates showed an antioxidant capacity in brain and liver of D-galactose treated mice. In addition, it was also reported that Mg and Se play important roles in SOD and GPx activities, respectively. Uzun and Kalender (2013) used chlorpyrifos, an organophosphorus insecticide, to induce hepatotoxic and hematologic changes in rats, but they observed that catechin can attenuate the chlorpyrifos-induced hepatotoxicity by increasing GPx and glutathione-S-transferase activities and decreasing MDA contents. Meanwhile, chlorogenic acid elevated SOD, CAT, and GPx activities with concomitantly decreased lipid peroxidation of liver and kidney in streptozotocin-nicotinamide induced type-2 diabetic rats. Hence, it is reasonable to assume that increased antioxidant capacities and decreased damage in livers of HFCD fed hamsters supplemented with BV should be highly related to the components, i.e. amino acid profile, mineral profile, and polyphenol contents, as well as the lowered liver lipid accumulations.

In analyses of amino acids, minerals and polyphenols, BV contained abundant essential amino acids and hydrophobic amino acids. Mg, K, Ca, Fe, Mn, and Se were measured in BV where K and Mg were major. Gallic acid, catechin, chlorogenic acid, p-hydroxybezoic acid, p-cumeric acid, ferulic acid, and sinapic acid were also identified in BV where catechin and chlorogenic acid were the majorities. Meanwhile, the lipid-lowering and antioxidant effects of BV were also investigated via a hamster model. BV supplementation apparently decreased weight gain (g and %), relative size of visceral fat, serum/liver TC levels, serum cardiac index, and hepatic TBARS values and damage indices (serum ALT and hepatic TNF-α and IL-1β) but increased fecal lipid contents and hepatic antioxidant capacities (GSH level, TEAC level, CAT activity, and GPx activity) in HFCD fed hamsters. To sum up, those benefits could be attributed to a synergetic effect of compounds in BV.

Analysis of pecan nut (Carya illinoinensis) unsaponifiable fraction – Effect of ripening stage on phytosterols and phytostanols composition

Intidhar Bouali, Hajer Trabelsi, Wahid Herchi, Lucy Martine, et al.
Food Chemistry 164 (2014) 309–316
http://dx.doi.org/10.1016/j.foodchem.2014.05.029

Changes in 4-desmethylsterol, 4-monomethylsterol, 4,4-dimethylsterol and phytostanol composition were quantitatively and qualitatively investigated during the ripening of three varieties of Tunisian grown pecan nuts. These components have many health benefits, especially in lowering LDL-cholesterol and preventing heart disease. The phytosterol composition of whole pecan kernel was quantified by Gas Chromatography–Flame Ionization Detection (GC–FID) and identified by Gas Chromatography–Mass Spectrometry (GC–MS). Fifteen phytosterols and one phytostanol were quantified. The greatest amount of phytosterols (2852.5 mg/100 g of oil) was detected in Mahan variety at 20 weeks after the flowering date (WAFD). Moore had the highest level of phytostanols (7.3 mg/100 g of oil) at 20 WAFD. Phytosterol and phytostanol contents showed a steep decrease during pecan nut development. Results from the quantitative characterization of pecan nut oils revealed that β-sitosterol, D5-avenasterol, and campesterol were the most abundant phytosterol compounds at all ripening stages.

Association between HMW adiponectin, HMW-total adiponectin ratio and early-onset coronary artery disease in Chinese population

Ying Wang, Aihua Zheng, Yunsheng Yan, Fei Song, et al.
Atherosclerosis 235 (2014) 392-397
http://dx.doi.org/10.1016/j.atherosclerosis.2014.05.910

Objective: Adiponectin is an adipose-secreting protein that shows atheroprotective property and has inverse relation with coronary artery disease (CAD). High-molecular weight (HMW) adiponectin is reported as the active form of adiponectin. In the present study, we aimed to investigate the association between total adiponectin, HMW adiponectin, HMW-total adiponectin ratio and the severity of coronary atherosclerosis, and to compare their evaluative power for the risk of CAD. Methods: Serum levels of total and HMW adiponectin were measured in 382 early-onset CAD (EOCAD) patients and 305 matched controls undergoing coronary angiography by enzyme-linked immunosorbent assay (ELISA). Gensini score was used to evaluate the severity of coronary atherosclerosis. Results: CAD onset age was positively correlated with HMW adiponectin (r = 0.383, P < 0.001) and HMW-total adiponectin ratio (r = 0.429, P < 0.001) in EOCAD patients. Total and HMW adiponectin and HMW-total adiponectin ratio were all inversely correlated with Gensini score (r=0.417, r=0.637, r=0.578, respectively; all P < 0.001). Multivariate binary logistic regression analysis demonstrated that HMW adiponectin and HMW-total adiponectin ratio were both inversely correlated with the risk of CAD (P < 0.05). ROC analysis indicated that areas under the ROC curves of HMW adiponectin and HMW-total adiponectin ratio were larger than that of total adiponectin (P < 0.05). Conclusions: Adiponectin is cardioprotective against coronary atherosclerosis onset in EOCAD patients. HMW adiponectin and HMW-total adiponectin ratio show stronger negative associations with the severity of coronary atherosclerosis than total adiponectin does. HMW adiponectin and HMW-total adiponectin ratio are effective biomarkers for the risk of CAD in Chinese population.

Gender and age were well matched between patients and controls. EOCAD patients were tended to have a history of diabetes or hypertension, more current smoking, and more use of lipid lowering drugs. Levels of total cholesterol, LDL-c, FPG, HbA1c and triglycerides were significantly higher in the patients than in controls, while HDL-cholesterol, total adiponectin, HMW adiponectin, and HMW-total adiponectin ratio were significantly lower in the patients. EOCAD patients developed different degrees of coronary atherosclerosis, and had significantly higher levels of high-sensitivity CRP and larger circumferences of waist and hip than controls.

Spearman correlation coefficients between selected cardiovascular risk factors, Gensini score and adiponectin were significant. Total and HMW adiponectin and HMW-total adiponectin ratio were all inversely correlated with Gensini score, BMI and pack years of cigarette smoking. Total and HMW adiponectin were negatively associated with triglycerides and circumference of waist and hip. LDL-cholesterol and high-sensitivity CRP were inversely correlated with HMW adiponectin and HMW-total adiponectin ratio, while HDL-cholesterol and age were positively correlated with them. FPG was only inversely associated with HMW-total adiponectin ratio.

All participants were divided into four groups according to their Gensini score, group A (control, n = 305), group B (<20, n = 154), group C (20-40, n = 121) and group D (>40, n = 105). With the increasing of Gensini score, a stepwise downward trend was observed in levels of total and HMW adiponectin and HMW-total adiponectin ratio (P < 0.001). Specifically, total adiponectin of four groups were 1.58 (0.61-4.36) mg/ml, 1.21 (0.70-2.83) mg/ml, 1.00 (0.73-1.88) mg/ml, and 0.76 (0.37-1.19) mg/ml, respectively. Except group A with B and group B with C, the differences of pairwise comparisons among all the other groups were statistically significant (all P < 0.05). HMW adiponectin of four groups were 0.91 (0.39-3.26) mg/ml, 0.55 (0.32-1.49) mg/ml, 0.46 (0.21-0.876) mg/ml, and 0.23 (0.14-0.39) mg/ml, respectively. The differences of pairwise comparisons among all the other groups were statistically significant (all P < 0.05) except group B with C. HMW-total adiponectin ratio of four groups were 0.58 (0.31-0.81), 0.47 (0.26-0.69), 0.41 (0.24-0.57), and 0.36 (0.21-0.42), respectively. The differences of pairwise comparisons among all the other groups were statistically significant (all P < 0.05) except group B with C. In the model of multivariate binary logistic regression analysis, after adjustment for conventional cardiovascular risk factors, HMW adiponectin (OR = 0.234, P < 0.011) and HMW-total adiponectin ratio (OR = 0.138, P < 0.005) remained inversely correlated with the risk of CAD, while no significant association was observed between total adiponectin and CAD

Areas under the ROC curves were compared pairwise to identify the diagnostic power for CAD among total adiponectin, HMW adiponectin, and HMW-total adiponectin ratio. HMW adiponectin and HMW-total adiponectin ratio showed greater capability for identifying CAD than total adiponectin did (0.797 vs. 0.674, 0.806 vs. 0.674; respectively, all P < 0.05); however, no significant difference was observed between HMW and HMW-total ratio (P > 0.05).

Associations between total adiponectin, HMW adiponectin, HMW-total adiponectin ratio and the severity of coronary atherosclerosis

Associations between total adiponectin, HMW adiponectin, HMW-total adiponectin ratio and the severity of coronary atherosclerosis in EOCAD patients (evaluated by Gensini score). *P < 0.05; **P < 0.001; ***P < 0.005 by Mann-Whitney U test.

Compares diagnostic power

Compares diagnostic power

Fig. Compares diagnostic power among total adiponectin, HMW adiponectin and HMW-total adiponectin ratio for CAD by ROC curves. Diagnostic power for CAD was based on discriminating patients with or without coronary atherosclerosis. The area under the curve for HMW-total adiponectin ratio (dotted black line) was larger than that for total adiponectin (fine black line) (0.806 [95%CI 0.708-0.903] vs. 0.674 [95%CI 0.552-0.797], P < 0.05) and HMW adiponectin (bold black line) (0.806 [95%CI 0.708-0.903] vs. 0.797 [95%CI 0.706-0.888], no statistically difference). Sensitivity, specificity and optimal cut off value for them were total adiponectin (57.38%, 75.86%, 1.11 mg/ml), HMW (55.74%, 93.1%, 0.49 mg/ml) and H/T (78.69%, 75.86%, 0.52), respectively.

There are two strengths in our study. One is the precise Gensini scoring system to carefully evaluate stenosis of coronary artery or branches > 0% diameter as coronary lesion, another is the specific study subjects of EOCAD in a Chinese Han population that is particularly genetically determined and not influenced by racial/ethnic disparities. The limitations of our study lie in the interference of medications such as the effect of lipid lowering drugs on the levels of adiponectin, and cardiovascular risk factors. Smoking is a conventional cardiovascular risk factor, whose interaction with HMW adiponectin level is rarely investigated, but it has been revealed to be associated with HMW adiponectin level in men according to the study from Kawamoto R et al. We did not adjust the result for the pack/year variable in the multivariate logistic regression analysis for the limitation of small sample size of male subjects in our study. The relatively small study sample also restrained our conclusion generalizable to all populations. Future researches in larger study samples and different populations are in need to validate our findings, and to explore the association of smoking with adiponectin in male subgroup analysis, and to investigate the potential mechanisms by which adiponectin affects the progression of coronary atherosclerosis.

In summary, the present study has demonstrated that adiponectin is protective against coronary atherosclerosis onset in EOCAD patients. HMW adiponectin and HMW-total adiponectin ratio show stronger negative associations with the severity of coronary atherosclerosis than total adiponectin does. HMW adiponectin and HMW-total adiponectin ratio are more effective biomarkers for the risk of CAD than total adiponectin.

Berberis aristata combined with Silybum marianum on lipid profile in patients not tolerating statins at high doses

Giuseppe Derosa, Davide Romano, Angela D’Angelo, Pamela Maffioli
Atherosclerosis 239 (2015) 87-92
http://dx.doi.org/10.1016/j.atherosclerosis.2014.12.043

Aim: To evaluate the effects of Berberis aristata combined with Silybum marianum in dyslipidemic patients intolerant to statins at high doses.
Methods: 137 euglycemic, dyslipidemic subjects, with previous adverse events to statins at high doses, were enrolled. Statins were stopped for 1 month (run-in), then they were re-introduced at the half of the previously taken dose. At randomization, patients tolerating the half dose of statin, were assigned to
add placebo or B. aristata/S. marianum 588/105 mg, 1 tablet during the lunch and 1 tablet during the dinner, for six months. We evaluated lipid profile and safety parameters variation at randomization, and after 3, and 6 months.
Results: B. aristata/S. marianum reduced fasting plasma glucose (-9 mg/dl), insulin (-0.7 mU/ml), and HOMA-index (-0.35) levels compared to baseline and also to placebo. Lipid profile did not significantly change after 6 months since the reduction of statin dosage and the introduction of B. aristata/S. marianum, while it worsened in the placebo group both compared to placebo and with active treatment (+23.4 mg/dl for total cholesterol, +19.6 mg/dl for LDL-cholesterol, +23.1 mg/dl for triglycerides with placebo compared to B. aristata/S. marianum). We did not record any variations of safety parameters
in either group. Conclusions: B. aristata/S. marianum can be considered as addition to statins in patients not tolerating high dose of these drugs.

Statins, also known as 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, are effective medications for reducing the risk of death and future cardiovascular disease. In the latest years, however, statin intolerance (including adverse effects related to quality of life, leading to decisions to decrease or stop the use of an otherwise-beneficial drug) has come to the forefront of clinical concern, whereas the safety of statins has come to be regarded as largely favorable. Statin intolerance is defined as any adverse symptoms, signs, or laboratory abnormalities attributed by the patient or physician to the statin and in most cases perceived by the patient to interfere unacceptably with activities of daily living, leading to a decision to stop or reduce statin therapy. The physician might also decide to stop or reduce statin therapy on the basis of clinical/laboratory assessment [abnormal liver function tests, creatine phosphokinase values (CPK)] suggesting undue risk. Adverse events are more common at higher doses of statins, and often contribute to patients low adherence to treatment. For this reason, researchers are testing alternative strategies for lipid treatment when statin intolerance is recognized. One strategy to reduce the risk of statin-induced adverse events includes using a low-dose of statin combined with nonstatin drugs in order to achieve the goals of therapy. Nonstatin drugs include nutraceuticals; in the latest years relatively large number of dietary supplements and nutraceuticals have been studied for their supposed or demonstrated ability to reduce cholesterolemia in humans, in particular Berberis Aristata, has been studied in randomized clinical trials and proved to be effective in improving lipid profile. In particular, B. aristata acts up-regulating LDL-receptor (LDL-R) expression independent of sterol regulatory element binding proteins, but dependent on extracellular signal-regulated kinases (ERK) and c-Jun N-terminal kinase (JNK) activation leading to total cholesterol (TC) and LDL-C reduction of about 30 and 25%, respectively. Hwever, B. aristata is a problem in terms of oral bioavailability, affected by a P-glycoprotein (P-gp) mediated gut extrusion process. P-gp seems to reduce by about 90% the amount of B. aristata able to cross the enterocytes, but the use of a potential P-gp inhibitor could ameliorate its oral poor bioavailability improving its effectiveness. Among the potential Pgp inhibitors, silymarin from S. marianum, an herbal drug used as liver protectant, could be considered a good candidate due to its high safety profile.

Analyzing the results of our study, it can appear, at a first glance, that B. aristata/S. marianum has a neutral effect of lipid profile that did not change during the study after the addition of the nutraceutical combination. This lack of effect, however, is only apparent, because, when we analyzed what happens in placebo group, we observed a worsening of lipid profile after statin dose reduction. In other words, the addition of B. aristata/S. marianum neutralized the worsening of lipid profile observed with placebo after statins dose reduction. These results are in line with what was reported by Kong et al., who evaluated the effects of a combination of berberine and simvastatin in sixty-three outpatients diagnosed with hypercholesterolemia. As compared with monotherapies, the combination showed an improved lipid lowering effect with 31.8% reduction of serum LDL-C, and similar efficacies were observed in the reduction of TC as well as Tg in patients. Considering the results of this study, B. aristata/S. marianum can be considered as addition to statins in patients not tolerating high dose of these drugs.

CETP inhibitors downregulate hepatic LDL receptor and PCSK9 expression in vitro and in vivo through a SREBP2 dependent mechanism

Bin Dong, Amar Bahadur Singh, Chin Fung, Kelvin Kan, Jingwen Liu
Atherosclerosis 235 (2014) 449-462
http://dx.doi.org/10.1016/j.atherosclerosis.2014.05.931

Background: CETP inhibitors block the transfer of cholesteryl ester from HDL-C to VLDL-C and LDL-C, thereby raising HDL-C and lowering LDL-C. In this study, we explored the effect of CETP inhibitors on hepatic LDL receptor (LDLR) and PCSK9 expression and further elucidated the underlying regulatory mechanism. Results: We first examined the effect of anacetrapib (ANA) and dalcetrapib (DAL) on LDLR and PCSK9 expression in hepatic cells in vitro. ANA exhibited a dose-dependent inhibition on both LDLR and PCSK9 expression in CETP-positive HepG2 cells and human primary hepatocytes as well as CETP-negative mouse primary hepatocytes (MPH). Moreover, the induction of LDLR protein expression by rosuvastatin in MPH was blunted by cotreatment with ANA. In both HepG2 and MPH ANA treatment reduced the amount of mature form of SREBP2 (SREBP2-M). In vivo, oral administration of ANA to dyslipidemic C57BL/6J mice at a daily dose of 50 mg/kg for 1 week elevated serum total cholesterol by approximately 24.5% (p < 0.05%) and VLDL-C by 70% (p < 0.05%) with concomitant reductions of serum PCSK9 and liver LDLR/SREBP2-M protein. Finally, we examined the in vitro effect of two other strong CETP inhibitors evacetrapib and torcetrapib on LDLR/PCSK9 expression and observed a similar inhibitory effect as ANA in a concentration range of 1-10 µM. Conclusion: Our study revealed an unexpected off-target effect of CETP inhibitors that reduce the mature form of SREBP2, leading to attenuated transcription of hepatic LDLR and PCSK9. This negative regulation of SREBP pathway by ANA manifested in mice where CETP activity was absent and affected serum cholesterol metabolism.

Effect of Eclipta prostrata on lipid metabolism in hyperlipidemic animals

Yun Zhao, Lu Peng, Wei Lu, Yiqing Wang, Xuefeng Huang, et al.
Experimental Gerontology 62 (2015) 37–44
http://dx.doi.org/10.1016/j.exger.2014.12.017

Eclipta prostrata (Linn.) Linn. is a traditional Chinese medicine and has previously been reported to have hypolipidemic effects. However, its mechanism of action is not well understood. This study was conducted to identify the active fraction of Eclipta, its toxicity, its effect on hyperlipidemia, and its mechanism of action. The ethanol extract (EP) of Eclipta and fractions EPF1–EPF4, obtained by eluting with different concentrations of ethanol from a HPD-450 macroporous resin column chromatography of the EP, were screened in hyperlipidemic mice for lipid lowering activity, and EPF3 was the most active fraction. The LD50 of EPF3 was undetectable because no mice died with administration of EPF3 at 10.4 g/kg. Then, 48 male hamsters were used and randomly assigned to normal chow diet, high-fat diet, high-fat diet with Xuezhikang (positive control) or EPF3 (75, 150 and 250 mg/kg) groups. We evaluated the effects of EPF3 on body weight gain, liver weight gain, serum lipid concentration, antioxidant enzyme activity, and the expression of genes involved in lipid metabolism in hyperlipidemic hamsters. The results showed that EPF3 significantly decreased body-weight gain and liver-weight gain and reduced the serum lipid levels in hyperlipidemic hamsters. EPF3 also increased the activities of antioxidant enzymes; upregulated the mRNA expression of peroxisome proliferator-activated receptor α (PPARα), low density lipoprotein receptor (LDLR), lecithin-cholesterol transferase (LCAT) and scavenger receptor class B type Ι receptor (SR-BI); and down-regulated the mRNA expression of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGR) in the liver. These results indicate that EPF3 ameliorates hyperlipidemia, in part, by reducing oxidative stress and modulating the transcription of genes involved in lipid metabolism.

Although Eclipta has long been used as a food additive, no studies or reports have clearly shown any liver or kidney toxicity from its use. Therefore, E. prostrata is safe and beneficial for preventing hyperlipidemia in experimental animals and can be used as an alternative medicine for the regulation of dyslipidemia.

Effect of high fiber products on blood lipids and lipoproteins in hamsters

HE Martinez-Floresa, Y Kil Chang, F Martinez-Bustosc, V Sgarbieri
Nutrition Research 24 (2004) 85–93
http://dx.doi.org:/10.1016/S0271-5317(03)00206-9

Serum and liver lipidemic responses in hamsters fed diets containing 2% cholesterol and different dietary fiber sources were studied. The following diets were made from: a) the control diet made from extruded cassava starch (CSH) contained 9.3% cellulose, b) cassava starch extruded with 9.7% resistant starch (CS-RS), c) cassava starch extruded with 9.9% oat fiber (CS-OF), d) the reference diet contained 9.5% cellulose, and no cholesterol was added. Total cholesterol, LDLVLDL-cholesterol and triglycerides were significantly lower (P < 0.05) in serum of hamsters fed on the CS-RS (17.87%, 62.92% and 9.17%, respectively) and CS-OF (15.12%, 67.41% and 18.35%, respectively) diets, as compared to hamster fed with the CSH diet. Similar results were found in the livers of hamsters fed on the CS-RS and CS-OF diets, as compared to hamsters fed with the CSH diet. The diets containing these fibers could be used as active ingredients in human diets to improve the human health.

A new piece in the puzzling effect of n-3 fatty acids on atherosclerosis?

Wilfried Le Goff
Atherosclerosis 235 (2014) 358-362
http://dx.doi.org/10.1016/j.atherosclerosis.2014.03.038

Omega-3 fatty acids (ω-3) FA are reported to be protective against cardiovascular disease (CVD), notably through their beneficial action on atherosclerosis development. In this context dietary intake of long chain marine eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is recommended and randomised trials largely support that EPA and DHA intake is associated with a reduction of CVD. However, mechanisms governing the atheroprotective action of ω-3 FA are still unclear and numerous studies using mouse models conducted so far do not allow to reach a precise view of the cellular and molecular effects of ω-3 FA on atherosclerosis. In the current issue of Atherosclerosis, Chang et al. provide important new information on the anti-atherogenic properties of ω-3 FA by analyzing the incremental replacement of saturated FA by pure fish oil as a source of EPA and DHA in Ldlr -/- mice fed a high fat/high cholesterol diet.

Cardiovascular disease (CVD) is the leading causes of death in the world and is frequently associated with atherosclerosis, a pathology characterized by the accumulation of lipids, mainly cholesterol in the arterial wall. Among major risk factors for CVD, circulating levels of lipids and more especially those originating from diets are closely linked to development of atherosclerosis. In this context, not only cholesterol, but also dietary fatty acids (FA) may appear particularly deleterious in regards to atherosclerosis and associated CVD. However, although saturated fats are proatherogenic, omega-3 fatty acids (ω-3 FA), and more especially long-chain marine eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), exert atheroprotective properties through several potential underlying mechanisms. Therefore, the intake of EPA and DHA is recommended around the world and randomised trials with ω-3 FA confirmed that EPA and DHA intake reduced risk for CVD events. However benefits of ω-3 FA intake were challenged by recent clinical trials that failed to replicate protective effects of EPA + DHA on CVD, raising the controversy on the healthy side of marine ω-3 FA.

Animal models are commonly employed in order to decipher mechanisms by which ω-3 FA exert their beneficial actions regarding lipid metabolism and atherosclerosis. Since the last past 20 years, mouse models, and more especially genetically modified mouse models, became the reference model to evaluate the effects of dietary fatty acids, especially ω-3 FA, on atherosclerosis development [7-20]. However, the use of different mouse models of atherosclerosis (Apoe-/-, Ldlr-/-, double Apoe-/- x Ldlr-/- , Ldlr-/- x hApoB mice), as well as diet composition (chow, high cholesterol, high fat, high cholesterol/high fat), source of ω-3 FA supplementation (fish oil, perilla seed oil, flaxseed, pure ALA, EPA or DHA), duration of the diet (from 4 to 32 weeks), size of atherosclerotic lesions in control animals (from 51 to 700.103 mm2) in

those studies led to heterogeneous results and therefore to a partial understanding of the effects of ω-3 FA on atherosclerosis.

Contrary to what observed in Apoe-/- mice, dietary supplementation of Ldlr-/- mice with ω-3 FA led to a reproducible reduction of aortic atherosclerosis, although to various degrees, confirming that Ldlr-/- mice constitute the most appropriate model for studying the atheroprotective effects of ω-3 FA. When evaluated, the decrease of atherosclerosis upon ω-3 FA-rich diet was accompanied by a reduction in the macrophage content as well as inflammation in aortic lesions highlighting the major impact of ω-3 FA on monocyte recruitment and subsequent macrophage accumulation in the arterial wall. However, although supplementation with ω-3 FA allows an efficacious lowering of plasma lipid levels in humans, studies in mouse models suggest that the antiatherogenic action of ω-3 FA is independent of any effects on plasma cholesterol or triglyceride levels. However, that must be asserted with caution as lipid metabolism is quite different in mouse in comparison to humans, highlighting the need to study in the future the effects of ω-3 FA on atherosclerosis in a mouse model exhibiting a more “humanized” lipid metabolism as achieved in hApoB/CETP mice.

In a previous issue of Atherosclerosis, Chang et al. reevaluate the impact of fish oil ω-3 FA on atherosclerosis development by operating an incremental replacement of saturated fats (SAT) by ω-3 FA (pure fish oil, EPA- and DHA-rich) in Ldlr-/- mice fed a high-fat (21%, w/w)/high-cholesterol (0.2%, w/w) diet for a 12-week period. This experimental approach is quite pertinent as dietary fat intake in developed countries, as in United States, derived mostly from saturated FA and is poor in ω-3 FA. Then, using this strategy the authors were able to evaluate the potential beneficial effects of a supplementation with fish oil ω-3 FA in a dietary context for which ω-3 FA intake is relevant.

Here, Chang et al. demonstrated that the progressive increase of dietary intake of fish oil ω-3 FA (EPA and DHA) abrogated the deleterious effects of a SAT diet, thereby suggesting that a dietary ω-3 FA intake on a SAT background is potentially efficient to decrease CVD in humans. Indeed, replacement of SAT by fish oil ω-3 FA markedly reduced plasma cholesterol and triglycerides levels and abolished diet-induced atherosclerosis mediated by SAT in Ldlr-/-mice. To note that in the present study, Ldlr-/- mice only developed small atherosclerosic lesions (~100.103 mm2) after 12 weeks of diet with SAT.

As previously reported, decreased atherosclerotic lesions were accompanied by a reduced content of aortic macrophages and inflammation. Based on their previous works, the authors proposed that the reduction of atherosclerosis upon ω-3 FA resulted from an impairment of cholesterol uptake by arterial macrophages consecutive to the decrease of Lipoprotein Lipase (LPL) expression in those cells. Indeed, beyond its lipolysis action on triglycerides, LPL was reported to promote lipid accumulation, in particular in macrophages, by binding to lipoproteins and cell surface proteoglycans and then acting as a bridging molecule that facilitates cellular lipid uptake. Coherent with this mechanism, macrophage LPL expression was reported to promote foam cell formation and atherosclerosis. In the present study, replacement of SAT by ω-3 FA both decreased expression and altered distribution of arterial LPL. Such a mechanism for ω-3 FA (EPA and DHA) was proposed by this group in earlier studies to favor reduction of arterial LDL-cholesterol. It is noteworthy that lipid rafts alter distribution of LPL at the cell surface and subsequently the LPL dependent accumulation of lipids in macrophages and foam cell formation. As incorporation of ω-3 FA, such as DHA, into cell membrane phospholipids disrupts lipid rafts organization, it cannot be exclude that reduction of lipid accumulation in arterial macrophages upon addition of ω-3 FA results in part from an impairment of the localization and of the anchoring function of LPL at the cell surface of macrophages. Indeed Chang et al. observed that progressive replacement of SAT by ω-3 FA affected aortic FA composition leading to a pronounced increase of arterial EPA and DHA, then suggesting that content of ω-3 FA in macrophage membrane may be equally altered. However, the implication of LPL in the atheroprotective effects of ω-3 FA need to be validated using an appropriate mouse model for which LPL expression may be controlled.

Among the various mechanisms by which ω-3 FA exert anti-inflammatory properties, EPA and DHA repressed inflammation by shutting down NF-kB activation in macrophages. Since expression of TLR-4 and NF-kB target genes, IL-6 and TNFα, in aorta from mice fed diets containing ω-3 FA were decreased when compared to SAT, those results strongly support the contention that ω-3 FA repress inflammation by inhibiting the TLR4/NF-kB signaling cascade likely through the macrophage ω-3 FA receptor GPR120.

Although further studies are needed to explore the complete spectrum of actions of ω-3 FA on atherosclerosis development and CVD, this study provides important information that supports that ω-3 FA intake is a pertinent strategy to reduce risk of CVD.

Effects of dietary hull-less barley β-glucan on the cholesterol metabolism of hypercholesterolemic hamsters

Li-Tao Tong, Kui Zhong, Liya Liu, Xianrong Zhou, Ju Qiu, Sumei Zhou
Food Chemistry 169 (2015) 344–349
http://dx.doi.org/10.1016/j.foodchem.2014.07.157

The aim of the present study is to investigate the hypocholesterolemic effects of dietary hull-less barley β-glucan (HBG) on cholesterol metabolism in hamsters which were fed a hypercholesterolemic diet. The hamsters were divided into 3 groups and fed experimental diets, containing 5‰ HBG or 5‰ oat β-glucan (OG), for 30 days. The HBG, as well as OG, lowered the concentration of plasma LDL-cholesterol significantly. The excretion of total lipids and cholesterol in feces were increased in HBG and OG groups compared with the control group. The activity of 3-hydroxy-3-methyl glutaryl-coenzyme A (HMG-CoA) reductase in liver was reduced significantly in the HBG group compared with the control and OG groups. The activity of cholesterol 7-α hydroxylase (CYP7A1) in the liver, in the HBG and OG groups, was significantly increased compared with the control group. The concentrations of acetate, propionate and total short chain fatty acids (SCFAs) were not significantly different between the HBG and control groups. These results indicate that dietary HBG reduces the concentration of plasma LDL cholesterol by promoting the excretion of fecal lipids, and regulating the activities of HMG-CoA reductase and CYP7A1 in hypercholesterolemic hamsters.

Effects of dietary wheat bran arabinoxylans on cholesterolmetabolism of hypercholesterolemic hamsters

Li-Tao Tong, Kui Zhong, Liya Liu, Ju Qiu, Lina Guo, et al.
Carbohydrate Polymers 112 (2014) 1–5
http://dx.doi.org/10.1016/j.carbpol.2014.05.061

The aim of the present study is to investigate the effects of dietary wheat bran arabinoxylans (AXs) on cholesterol metabolism in hypercholesterolemic hamsters. The hamsters were divided into 3 groups and fed the experimental diets containing AXs or oat β-glucan at a dose of 5 g/kg for 30 days. As the results,the AXs lowered plasma total cholesterol and LDL-cholesterol concentrations, and increased excretions of total lipids, cholesterol and bile acids, as well as oat β-glucan. The AXs reduced the activity of 3-hydroxy-3-methyl glutaryl-coenzyme A (HMG-CoA) reductase, and increased the activity of cholesterol 7-α hydroxylase (CYP7A1) in liver. Moreover, the AXs increased propionate and the total short-chain fatty acids (SCFAs) concentrations. These results indicated that dietary AXs reduced the plasma total cholesterol and LDL-cholesterol concentrations by promoting the excretion of fecal lipids, regulating the activities of HMG-CoA reductase and CYP7A1, and increasing colonic SCFAs in hamsters.

High-fructose feeding promotes accelerated degradation of hepatic LDL receptor and hypercholesterolemia in hamsters via elevated circulating PCSK9 levels

Bin Dong, Amar Bahadur Singh, Salman Azhar, Nabil G. Seidah, Jingwen Liu
Atherosclerosis 239 (2015) 364-374
http://dx.doi.org/10.1016/j.atherosclerosis.2015.01.013

Background: High fructose diet (HFD) induces dyslipidemia and insulin resistance in experimental animals and humans with incomplete mechanistic understanding. By utilizing mice and hamsters as in vivo models, we investigated whether high fructose consumption affects serum PCSK9 and liver LDL receptor (LDLR) protein levels. Results: Feeding mice with an HFD increased serum cholesterol and reduced serum PCSK9 levels as compared with the mice fed a normal chow diet (NCD). In contrast to the inverse relationship in mice, serum PCSK9 and cholesterol levels were co-elevated in HFD-fed hamsters. Liver tissue analysis revealed that PCSK9 mRNA and protein levels were both reduced in mice and hamsters by HFD feeding, however, liver LDLR protein levels were markedly reduced by HFD in hamsters but not in mice. We further showed that circulating PCSK9 clearance rates were significantly lower in hamsters fed an HFD as compared with the hamsters fed NCD, providing additional evidence for the reduced hepatic LDLR function by HFD consumption. The majority of PCSK9 in hamster serum was detected as a 53 kDa N-terminus cleaved protein. By conducting in vitro studies, we demonstrate that this 53 kDa truncated hamster PCSK9 is functionally active in promoting hepatic LDLR degradation. Conclusion: Our studies for the first time demonstrate that high fructose consumption increases serum PCSK9 concentrations and reduces liver LDLR protein levels in hyper-lipidemic hamsters. The positive correlation between circulating cholesterol and PCSK9 and the reduction of liver LDLR protein in HFD-fed hamsters suggest that hamster is a better animal model than mouse to study the modulation of PCSK9/LDLR pathway by atherogenic diets.

High-oleic canola oil consumption enriches LDL particle cholesteryl oleate content and reduces LDL proteoglycan binding in humans

Peter J.H. Jones, Dylan S. MacKay, Vijitha K. Senanayake, Shuaihua Pu, et al.
Atherosclerosis 238 (2015) 231-238
http://dx.doi.org/10.1016/j.atherosclerosis.2014.12.010

Oleic acid consumption is considered cardio-protective according to studies conducted examining effects of the Mediterranean diet. However, animal models have shown that oleic acid consumption increases LDL particle cholesteryl oleate content which is associated with increased LDL-proteoglycan binding and atherosclerosis. The objective was to examine effects of varying oleic, linoleic and docosahexaenoic acid consumption on human LDL-proteoglycan binding in a non-random subset of the Canola Oil Multi-center Intervention Trial (COMIT) participants. COMIT employed a randomized, double-blind, five-period, crossover trial design. Three of the treatment oil diets: 1) a blend of corn/safflower oil (25:75); 2) high oleic canola oil; and 3) DHA-enriched high oleic canola oil were selected for analysis of LDL-proteoglycan binding in 50 participants exhibiting good compliance. LDL particles were isolated from frozen plasma by gel filtration chromatography and LDL cholesteryl esters quantified by mass-spectrometry. LDL-proteoglycan binding was assessed using surface plasmon resonance. LDL particle cholesterol ester fatty acid composition was sensitive to the treatment fatty acid compositions, with the main fatty acids in the treatments increasing in the LDL cholesterol esters. The corn/safflower oil and high-oleic canola oil diets lowered LDL-proteoglycan binding relative to their baseline values (p < 0.0005 and p < 0.0012, respectively). At endpoint, high-oleic canola oil feeding resulted in lower LDL-proteoglycan binding than corn/safflower oil (p < 0.0243) and DHA-enriched high oleic canola oil (p < 0.0249), although high-oleic canola oil had the lowest binding at baseline (p < 0.0344). Our findings suggest that high-oleic canola oil consumption in humans increases cholesteryl oleate percentage in LDL, but in a manner not associated with a rise in LDL-proteoglycan binding.

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Sex Hormones

Author: Larry H Bernstein, MD, FCAP

A steroid hormone is a steroid that acts as a hormone. Steroid hormones can be
grouped into five groups by the receptors to which they bind:

  • glucocorticoids,
  • mineralocorticoids,
  • androgens,
  • estrogens, and
  • progestogens.
  • Vitamin D derivatives, are a sixth closely related hormone system with homologous receptors. They have some of the characteristics of true steroids as receptor ligands.

Steroid hormones help control metabolism, inflammation, immune functions, salt
and water balance, development of sexual characteristics, and the ability to withstand
illness and injury. The term steroid describes both hormones produced by the body
and artificially produced medications that duplicate the action for the naturally occurring steroids

The natural steroid hormones are generally synthesized from cholesterol in the gonads and adrenal glands. These forms of hormones are lipids. They can pass through the cell membrane as they are fat-soluble,[4] and then bind to steroid hormone receptors (which may be nuclear or cytosolic depending on the steroid hormone) to bring about changes within the cell. Steroid hormones are generally carried in the blood, bound to specific carrier proteins such as sex hormone-binding globulin or corticosteroid-binding globulin. Further conversions and catabolism
occurs in the liver, in other “peripheral” tissues, and in the target tissues.

Synthetic steroids and sterols

A variety of synthetic steroids and sterols have also been contrived. Most are
steroids, but some non-steroidal molecules can interact with the steroid receptors
because of a similarity of shape. Some synthetic steroids are weaker or stronger
than the natural steroids whose receptors they activate.

Some examples of synthetic steroid hormones:
Glucocorticoids: alclometasone, prednisone, dexamethasone, triamcinolone
Mineralocorticoid: fludrocortisone
Vitamin D: dihydrotachysterol
Androgens: apoptone, oxandrolone, oxabolone, testosterone, nandrolone (also
known as anabolic steroids)
Estrogens: diethylstilbestrol (DES)
Progestins: danazol, norethindrone, medroxyprogesterone acetate,
17-Hydroxyprogesterone caproate.

Some steroid antagonists:
Androgen: cyproterone acetate
Progestins: mifepristone, gestrinone
http://www.en.wikipedia.org/wiki/Steroid

Steroid-Hormone-Synthesis

Steroid-Hormone-Synthesis

Steroidogenesis

Steroidogenesis


http://www.gfmer.ch/Books/Reproductive_health/Image171.gif

The regulation of spermatogenesis by androgens

Lee B. Smith, William H. Walker
Seminars in Cell & Developmental Biology 30 (2014) 2–13
http://dx.doi.org/10.1016/j.semcdb.2014.02.012

Testosterone is essential for maintaining spermatogenesis and male fertility.
However, the molecular mechanisms by which testosterone acts have not
begun to be revealed until recently. With the advances obtained from the use
of transgenic mice lacking or overexpressing the androgen receptor, the cell
specific targets of testosterone action as well as the genes and signaling pathways
that are regulated by testosterone are being identified. In this review, the critical
steps of spermatogenesis that are regulated by testosterone are discussed as well
as the intracellular signaling pathways by which testosterone acts. We also review
the functional information that has been obtained from the knock out of the androgen
receptor from specific cell types in the testis and the genes found to be regulated
after altering testosterone levels or androgen receptor expression.

The essence of female–male physiological dimorphism: Differential Ca2+-homeostasis
enabled by the interplay between farnesol-like endogenous sesquiterpenoids and
sex-steroids? The Calcigender paradigm

Arnold De Loof
General and Comparative Endocrinology 211 (2015) 131–146
http://dx.doi.org/10.1016/j.ygcen.2014.12.003

Ca2+ is the most omnipresent pollutant on earth, in higher concentrations a real
threat to all living cells. When [Ca2+]i rises above 100 nM (=resting level), excess
Ca2+ needs to be confined in the SER and mitochondria, or extruded by the different
Ca2+-ATPases. The evolutionary origin of eggs and sperm cells has a crucial, yet
often overlooked link with Ca2+-homeostasis. Because there is no goal whatsoever
in evolution, gametes did neither originate ‘‘with the purpose’’ of generating a progeny
nor of increasing fitness by introducing meiosis. The explanation may simply be that
females ‘‘invented the trick’’ to extrude eggs from their body as an escape strategy
for getting rid of toxic excess Ca2+ resulting from a sex-hormone driven increased
influx into particular cells and tissues.
The production of Ca2+-rich milk, seminal fluid in males and all secreted proteins
by eukaryotic cells may be similarly explained. This view necessitates an upgrade
of the role of the RER-Golgi system in extruding Ca2+. In the context of insect
metamorphosis, it has recently been (re)discovered that (some isoforms of) Ca2+-
ATPases act as membrane receptors for some types of lipophilic ligands, in
particular for endogenous farnesol-like sesquiterpenoids (FLS) and, perhaps, for
some steroid hormones as well.
A novel paradigm, tentatively named ‘‘Calcigender’’ emerges. Its essence is: gender-
specific physiotypes ensue from differential Ca2+-homeostasis enabled by genetic
differences, farnesol/FLS and sex hormones. Apparently the body of reproducing
females gets temporarily more poisoned by Ca2+ than the male one, a selective
benefit rather than a disadvantage.

Sex differences in the expression of estrogen receptor alpha within noradrenergic
neurons in the sheep brain stem

J.L. Rose, A.S. Hamlin, C.J. Scott
Domestic Animal Endocrinology 49 (2014) 6–13
http://dx.doi.org/10.1016/j.domaniend.2014.04.003

In female sheep, high levels of estrogen exert a positive feedback action
on gonadotropin releasing hormone (GnRH) secretion to stimulate a surge in
luteinizing hormone (LH) secretion. Part of this action appears to be via brain
stem noradrenergic neurons. By contrast, estrogen action in male sheep has
a negative feedback action to inhibit GnRH and LH secretion. To investigate
whether part of this sex difference is due to differences in estrogen action in
the brain stem, we tested the hypothesis that the distribution of estrogen
receptor a (ERα) within noradrenergic neurons in the brain stem differs
between rams and ewes. To determine the distribution of ERα, we used
double-label fluorescence immunohistochemistry for dopamine b-Hydroxylase,
as a marker for noradrenergic and adrenergic cells, and ERα. In the ventro-
lateral medulla (A1 region), most ERα-immunoreactive (-ir) cells were
located in the caudal part of the nucleus. Overall, there were more ERα-ir
cells in rams than ewes, but the proportion of double-labeled cells was did
not differ between sexes. Much greater numbers of ERα–ir cells were
found in the nucleus of the solitary tract (A2 region), but <10% were double
labeled and there were no sex differences. The majority of ERα-labeled cells
in this nucleus was located in the more rostral areas. Erα labeled cells were
found in several rostral brain stem regions but none of these were double
labeled and so were not quantified. Because there was no sex difference
in the number of ERα-ir cells in the brain stem that were noradrenergic,
the sex difference in the action of estrogen on gonadotropin secretion in
sheep is unlikely to involve actions on brain stem noradrenergic cells.

Androgens, estrogens, and second messengers

William Rosner, DJ Hryb, MS Khan, AM Nakhla, and NA Romas
Steroids 1998; 63:278 –281 PII S0039-128X(98)00017-8

Over the course of the last four decades, a detailed understanding of the
molecular mechanisms by which steroid hormones exert their effects has
evolved, and continues to evolve. The major focus of research in this area
has been on the manner in which steroid receptors activate transcription.
Pathways of steroid action other than by direct interaction with intracellular
receptors have received relatively little attention. However, there is a growing
body of evidence that steroid hormones exert effects through mechanisms
in addition to those involving their classic intracellular receptors. One such
mechanism is based on the observation that a number of cells have receptors
on their plasma membranes for the plasma protein, sex hormone binding
globulin (SHBG). It is the purpose of this review to briefly describe our current
knowledge of this system.

SHBG binds to a receptor (RSHBG) on cell membranes cAMP and the steroid-SHBG-RSHBG system
Biology of the SHBG-RSHBG system

Relation between the affinity of steroid for SHBG and its potency in inhibiting
the binding of SHBG to RSHBG.

KA (SHBG) = Association constant for SHBG and the indicated steroid.
Ki SHBG-RSHBG = The inhibition constant for the indicated steroid on the
binding of SHBG to RSHBG.

PSA secretion was stimulated by DHT. Although estradiol alone had no effect
on PSA secretion, it caused an increase equal to that seen with DHT if the
prostate tissue was first loaded with SHBG, e.g., if RSHBG was occupied by
SHBG. Because estradiol-SHBG increases intracellular cAMP, we ascertained
whether other compounds that raise cAMP (forskolin), or cAMP itself, could
increase PSA secretion. Such was the case. cAMP begins its signal cascade
by activating protein kinase A (PKA) so that if estradiol-SHBG increases PSA
secretion by a mechanism involving cAMP, inhibition of PKA should block
estradiol-SHBG-initiated PSA secretion. Estradiol-SHBG failed to stimulate
PSA when PKA was inhibited with PKI. On the other hand, DHT-stimulated
PSA secretion, which does not involve PKA, was not inhibited by PKI. That
the effect of estradiol-SHBG was independent of the estrogen receptor was
shown by the lack of inhibition of estrogen-stimulated PSA secretion by two
anti-estrogens, tamoxifen and ICI 164,284. The promoter of the PSA gene
has an androgen response element, and both PSA secretion and the
expression of PSA mRNA are androgen-regulated. We investigated the
effect of hydroxyflutamide and cyproterone acetate. Both potent anti-
androgens, on the E2-SHBG-mediated increase in PSA secretion. secretion.
They also blocked the effect of E2-SHBG on PSA secretion. Since E2 is
not exerting its effect by binding to the AR, e.g., it is not its cognate ligand,
the E2-induced secretion of PSA observed in this study reflects ligand-
independent activation of the AR.26 Thus, estradiol activates a typical
AR-mediated event, PSA synthesis and secretion, by activating SHBG-
RSHBG. These data make clear the fact that there is cross-talk between a
steroid hormone-engendered event at the cell membrane and a classic
intracellular steroid hormone receptor.
Abbreviations: PSA, prostate specific antigen; DHT, dihydrotestosterone;
E2, estradiol; PKI, inhibitor of protein kinase A; ICI 164,384 (a pure anti-
estrogen); 2MeOE2, 2 methoxyestradiol; Cypro, cyproterone acetate,
OHFlut, hydroxyflutamide.

Role of G protein-coupled estrogen receptor 1, GPER, in inhibition of oocyte
maturation by endogenous estrogens in zebrafish

Yefei Pang, Peter Thomas
Developmental Biology 342 (2010) 194–206
http://dx.doi.org:/10.1016/j.ydbio.2010.03.027

Estrogen inhibition of oocyte maturation (OM) and the role of GPER (formerly
known as GPR30) were investigated in zebrafish. Estradiol-17β (E2) and G-1,
a GPER-selective agonist, bound to zebrafish oocyte membranes suggesting
the presence of GPER which was confirmed by immunocytochemistry using
a specific GPER antibody. Incubation of follicle-enclosed oocytes with an
aromatase inhibitor, ATD, and enzymatic and manual removal of the ovarian
follicle cell layers significantly increased spontaneous OM which was partially
reversed by co-treatment with either 100 nM E2 or G-1. Incubation of
denuded oocytes with the GPER antibody blocked the inhibitory effects of
estrogens on OM, whereas microinjection of estrogen receptor alpha (ERα)
antisense oligonucleotides into the oocytes was ineffective. The results
suggest that endogenous estrogens produced by the follicle cells inhibit or
delay spontaneous maturation of zebrafish oocytes and that this estrogen
action is mediated through GPER. Treatment with E2 and G-1 also attenuated
the stimulatory effect of the teleost maturation-inducing steroid, 17,20 β-
dihyroxy-4-pregnen-3-one (DHP), on OM.  Moreover, E2 and G-1 down-
regulated the expression of membrane progestin receptor alpha (mPRα),
the intermediary in DHP induction of OM. Conversely DHP treatment caused
a N50% decline in GPER mRNA levels. The results suggest that estrogens
and GPER are critical components of the endocrine system controlling
the onset of OM in zebrafish. A model is proposed for the dual control of the
onset of oocyte maturation in teleosts by estrogens and progestins acting
through GPER and mPRα, respectively, at different stages of oocyte
development.
Reprint of ’’GPR30 mediates estrogen rapid signaling and neuroprotection’’

Hui Tang, Q Zhang, L Yang, Y Dong, M Khan, F Yang, DW Brann, R Wang
Molecular and Cellular Endocrinology 389 (2014) 92–98
http://dx.doi.org/10.1016/j.mce.2014.01.024
http://dx.doi.org/10.1016/j.mce.2014.05.005

G-protein-coupled estrogen receptor-30 (GPR30), also known as G-protein
estrogen receptor-1 (GPER1), is a putative extranuclear estrogen receptor
whose precise functions in the brain are poorly understood. Studies using
exogenous administration of the GPR30 agonist, G1 suggests that GPR30
may have a neuroprotective role in cerebral ischemia. However, the
physiological role of GPR30 in mediating estrogen (E2)-induced neuro-
protection in cerebral ischemia remains unclear. Also unclear is whether
GPR30 has a role in mediating rapid signaling by E2 after cerebral ischemia,
which is thought to underlie its neuroprotective actions. To address these
deficits in our knowledge, the current study examined the effect of antisense
oligonucleotide (AS) knockdown of GPR30 in the hippocampal CA1 region
upon E2-BSA induced neuroprotection and rapid kinase signaling in a rat
model of global cerebral ischemia (GCI). Immunohistochemistry demonstrated
that GPR30 is strongly expressed in the hippocampal CA1 region and
dentate gyrus, with less expression in the CA3 region. E2-BSA exerted
robust neuroprotection of hippocampal CA1 neurons against GCI, an effect
abrogated by AS knockdown of GPR30. Missense control oligonucleotides had
no effect upon E2-BSA-induced neuroprotection, indicating specificity of the
effect. The GPR30 agonist, G1 also exerted significant neuroprotection against
GCI. E2-BSA and G1 also rapidly enhanced activation of the prosurvival
kinases, Akt and ERK, while decreasing proapototic JNK activation. Importantly,
AS knockdown of GPR30 markedly attenuated these rapid kinase signaling
effects of E2-BSA. As a whole, the studies provide evidence of an important
role of GPR30 in mediating the rapid signaling and neuroprotective actions
of E2 in the hippocampus.
Regulation of brain microglia by female gonadal steroids

Pardes Habib, Cordian Beyer
Journal of Steroid Biochemistry & Molecular Biology 2015; 146: 3–14
http://dx.doi.org/10.1016/j.jsbmb.2014.02.018

Microglial cells are the primary mediators of the CNS immune defense system
and crucial for shaping inflammatory responses. They represent a highly
dynamic cell population which is constantly moving and surveying their
environment. Acute brain damage causes a local attraction and activation of
this  immune cell type which involves neuron-to-glia and glia-to-glia interactions.
The prevailing view attributes microglia a “negative” role such as defense and
debris elimination. More topical studies also suggest a protective and “positive”
regulatory function. Estrogens and progestins exert anti-inflammatory and
neuroprotective effects in the CNS in acute and chronic brain diseases.
Recent work revealed that microglial cells express subsets of classical and
non-classical estrogen and progesterone receptors in a highly dynamic way.
In this review article, we would like to stress the importance of microglia for
the spreading of neural damage during hypoxia, their susceptibility to functional
modulation by sex steroids, the potency of sex hormones to switch microglia
from a pro-inflammatory M1 to neuroprotective M2 phenotype, and the
regulation of pro-and anti-inflammatory properties including the inflammasome.
We will further discuss the possibility that the neuroprotective action of sex
steroids in the brain involves an early and direct modulation of local microglia
cell function. Neuroprotection by gonadal steroid hormones in acute brain
damage requires cooperation with astroglia and microglia

Sonja Johann, Cordian Beyer
http://dx.doi.org/10.1016/j.jsbmb.2012.11.006

The neuroactive steroids 17β-estradiol and progesterone control a broad
spectrum of neural functions. Besides their roles in the regulation of classical
neuroendocrine loops, they strongly influence motor and cognitive systems,
behavior, and modulate brain performance at almost every level. Such a
statement is underpinned by the widespread and lifelong expression pattern
of all types of classical and non-classical estrogen and progesterone receptors
in the CNS. The life-sustaining power of neurosteroids for tattered or seriously
damaged neurons aroused interest in the scientific community in the past years
to study their ability for therapeutic use under neuropathological challenges.
Documented by excellent studies either performed in vitro or in adequate animal
models mimicking acute toxic or chronic neuro-degenerative brain disorders,
both hormones revealed a high potency to protect neurons from damage
and saved neural systems from collapse. Unfortunately, neurons, astroglia,
microglia, and oligodendrocytes are comparably target cells for both steroid
hormones. This hampers the precise assignment and understanding of
neuroprotective cellular mechanisms activated by both steroids. In this article,
we strive for a better comprehension of the mutual reaction between these
steroid hormones and the two major glial cell types involved in the maintenance
of brain homeostasis, astroglia and microglia, during acute traumatic brain
injuries such as stroke and hypoxia. In particular, we attempt to summarize
steroid-activated cellular signaling pathways and molecular responses in these
cells and their contribution to dampening neuroinflammation and neural
destruction.

Photoperiod influences the ontogenetic expression of aromatase
and estrogen receptor α in the developing tilapia brain.

Li-Hsueh Wang, Ching-Lin Tsai
General and Comparative Endocrinology 2006; 145: 62–66
http://dx.doi.org:/10.1016/j.ygcen.2005.07.004

Neural development is determined not only by genetic regulation, but also
by environmental cues. Central estrogen-forming/estrogen-sensitive systems
play an important role in the neural development of the brain. In the present
study, the quantitative reverse transcription-polymerase chain reaction method
was used to investigate the effects of photoperiod on the ontogenetic
expression of aromatase and estrogen receptor a (ERα) in the developing
tilapia brain. Before day 5 post-hatch, brain aromatase mRNA expression was
significantly decreased by constant light but not influenced by constant darkness.
During this period, brain ERα mRNA expression was significantly increased
under both constant light and constant darkness. Between days 5 and 10, and
between days 10 and 15, neither brain aromatase nor brain ERα expression
was altered under constant darkness and constant light. These results indicate
that the ontogenetic expression of brain aromatase and brain ERα is not via a
light-inducing process but influenced by a light-entraining signal during the
very early period of development.

Orphanin FQ-ORL-1 Regulation of Reproduction and Reproductive Behavior in
the Female

Kevin Sinchak, Lauren Dalhousay, Nayna Sanathara
Vitamins and Hormones 187-220.  http://dx.doi.org/10.1016/bs.vh.2014.11.002

Orphanin FQ (OFQ/N) and its receptor, opioid receptor-like receptor-1 (ORL-1),
are expressed throughout steroid-responsive limbic and hypothalamic circuits
that regulate female ovarian hormone feedback and reproductive behavior
circuits. The arcuate nucleus of the hypothalamus (ARH) is a brain region
that expresses OFQ/N and ORL-1 important for both sexual behavior and
modulating estradiol feedback loops. Within the ARH, the activation of the
OFQ/N-ORL-1 system facilitates sexual receptivity (lordosis) through the
inhibition of β-endorphin neuronal activity. Estradiol initially activates ARH
β-endorphin neurons to inhibit lordosis. Simultaneously, estradiol upregulates
coexpression of OFQ/N and progesterone receptors and ORL-1 in ARH
β-endorphin neurons. Ovarian hormones regulate pre- and postsynaptic
coupling of ORL-1 to its G protein-coupled signaling pathways. When the
steroid-primed rat is nonreceptive, estradiol acts pre- and postsynaptically
to decrease the ability of the OFQ/N-ORL-1 system to inhibit ARH β-endorphin
neurotransmission. Conversely, when sexually receptive, ORL-1 signaling is
restored to inhibit β-endorphin neurotransmission. Although steroid signaling
that facilitates lordosis converges to deactivate ARH.
Estradiol Activates the Prostate Androgen Receptor and Prostate specific Antigen
Secretion through the Intermediacy of Sex Hormone-binding Globulin

Atif M. Nakhla, Nicholas A. Romas, and William Rosner
J Biol Chem Mar 14, 1997; 272(11): 6838–6841 http://www-jbc.stanford.edu/jbc/

These experiments were designed to examine the relationship between the
effects of steroid hormones mediated by classic intracellular steroid hormone
receptors and those mediated by a signaling system subserved at the plasma
membrane by a receptor for sex hormone binding globulin. It is known that
unliganded sex hormone-binding globulin (SHBG) binds to a receptor (RSHBG)
on prostate membranes. The RSHBG*SHBG complex is rapidly activated by
estradiol to stimulate adenylate cyclase, with a resultant increase in intracellular
cAMP. In this paper we examine the effect of this system on a prostate gene
product known to be activated by androgens, prostate-specific antigen.
We have shown previously that estradiol (E2) participates in a signaling
system that originates, not within the cell, but at the plasma membrane.
Through the intermediacy of the plasma protein, sex hormone-binding
globulin (SHBG), it causes the generation of cAMP. In brief, unliganded
SHBG binds to a receptor (RSHBG) on certain cell surfaces and the
RSHBG*SHBG complex is rapidly activated by E2 to stimulate adenylate cyclase,
with a resultant increase in intracellular cAMP. There is a paucity of information
on events subsequent to the generation of cAMP by this system. In this paper
we examine the effect of E2-SHBG-RSHBG on an androgen responsive gene.
The gene for prostate-specific antigen (PSA) contains an androgen response
element. After binding its cognate ligand, the androgen receptor (AR) interacts
with this response element to initiate PSA mRNA transcription and secretion.
We show that, in the absence of androgens, E2 in concert with SHBG*RSHBG,
acts at the cell membrane to cause secretion of PSA and that this effect is
blocked by anti-androgens. This observation provides a first functional link
between a classic steroid hormone receptor and a cell membrane-mediated
steroidal effect. In serum-free organ culture of human prostates,
dihydrotestosterone caused an increase in prostate specific antigen secretion.
This event was blocked by the anti-androgens cyproterone acetate and
hydroxyflutamide. In the absence of androgens, estradiol added to prostate
tissue, whose RSHBG was occupied by SHBG, reproduced the results seen
with dihydrotestosterone. Neither estradiol alone nor SHBG alone duplicated
these effects. The estradiol*SHBG-induced increase in prostate-specific
antigen was not blocked by anti-estrogens, but was blocked both by anti-
androgens and a steroid (2-methoxyestradiol) that prevents the binding of
estradiol to SHBG. Furthermore, an inhibitor of protein kinase A prevented
the estradiol*SHBG-induced increase in prostate-specific antigen but not
that which followed dihydrotestosterone. These data indicate that there is a
signaling system that amalgamates steroid-initiated intracellular events
with steroid-dependent occurrences generated at the cell membrane and
that the latter signaling system proceeds by a pathway that involves protein
kinase A.
Mechanisms of crosstalk between endocrine systems: Regulation of sex steroid
hormone synthesis and action by thyroid hormones

Paula Duarte-Guterman, Laia Navarro-Martín, Vance L. Trudeau
General and Comparative Endocrinology 203 (2014) 69–85
http://dx.doi.org/10.1016/j.ygcen.2014.03.015

Thyroid hormones (THs) are well-known regulators of development and
metabolism in vertebrates. There is increasing evidence that THs are also
involved in gonadal differentiation and reproductive function. Changes in TH
status affect sex ratios in developing fish and frogs and reproduction
(e.g., fertility), hormone levels, and gonad morphology in adults of species of
different vertebrates. In this review, we have summarized and compared the
evidence for cross-talk between the steroid hormone and thyroid axes and
present a comparative model. We gave special attention to TH regulation of
sex steroid synthesis and action in both the brain and gonad, since these are
important for gonad development and brain sexual differentiation and have
been studied in many species. We also reviewed research showing that
there is a TH system, including receptors and enzymes, in the brains and
gonads in developing and adult vertebrates. Our analysis shows that THs
influences sex steroid hormone synthesis in vertebrates, ranging from fish
to pigs. This concept of crosstalk and conserved hormone interaction has
implications for our understanding of the role of THs in reproduction, and
how these processes may be dysregulated by environmental endocrine
disruptors.
Inverse relationship between hSHBG affinity for testosterone and hSHBG
concentration revealed by surface plasmon resonance

Laurence Heinrich-Balard, Wael Zeinyeh, Henri Déchaud, Pascaline Rivory, et al.
Molecular and Cellular Endocrinology 399 (2015) 201–207
http://dx.doi.org/10.1016/j.mce.2014.10.002

A wide range of human sex hormone-binding globulin (hSHBG) affinity constants
for testosterone (KA_hSHBG) has been reported in literature. To bring new insight
on the KA_hSHBG value, we implemented a study of the molecular interactions
occurring between testosterone and its plasma transport proteins by using
surface plasmon resonance. The immobilization on the sensor-chip of a
testosterone derivative was performed by an oligoethylene glycol linker.
For different plasmas with hSHBG concentrations, an assessment of the
KA_hSHBG was obtained from a set of sensor-grams and curve-fitting these
data.We observed that KA_hSHBG decreased, from at least two decades,
when the plasma hSHBG concentration increased from 4.4 to 680 nmol/L.
Our study shows a wide biological variability of KA_hSHBG that is related
to the hSHBG concentration.
These unexpected results may have a physiological significance and question
the validity of current methods that are recommended for calculating free
testosterone concentrations to evaluate androgen disorders in humans.
Intracrinology in action: Importance of extragonadal sex steroid biosynthesis
and inactivation in peripheral tissues in both women and men.

Editorial
Journal of Steroid Biochemistry & Molecular Biology 145 (2015) 131–132
http://dx.doi.org/10.1016/j.jsbmb.2014.09.012

It seems appropriate, as introduction, to summarize the mechanisms at the
basis of the new paradigm of steroid biosynthesis in the human peripheral
tissues, namely intracrinology. While the first clinical proof of the role of
extragonadal sex steroid biosynthesis was obtained with combined androgen
blockade in men treated for prostate cancer, the first demonstration of the
efficacy of DHEA replacement therapy was on the symptoms of vulvovaginal
atrophy in postmenopausal women; (Archer, this issue).
DHEA is transformed specifically in each cell of each peripheral tissue into
the proper amounts of estrogens and/or androgens, depending upon the
local expression of the appropriate steroid forming enzymes; (Labrie, this issue).
Most importantly, the sex steroids synthesized and acting intracellularly in
peripheral tissues are also inactivated locally before being released in the
extracellular space, thus maintaining the serum levels of estradiol and
testosterone at biologically inactive concentrations, thus avoiding systemic
exposure to sex steroids during menopause as well illustrated by atrophy
of the endometrium.
As mentioned above, that extragonadal androgen biosynthesis is clinically
important became obvious in 1982 when the addition of the antiandrogen
flutamide to castration provided very exciting and unexpected beneficial results
(Labrie, this issue). In fact, combining a pure anti-androgen to castration has
been the first treatment shown to prolong life in prostate cancer and very clearly
confirmed by the prolongation of life of 2.2–4.8 months observed following
addition of MDV-3100 or abiraterone to castration resistant prostate cancer
patients (Grist et al., this issue). (Mizokami et al., this issue) very competently
complement the mechanisms potentially involved in extragonadal steroid
biosynthesis. A repeated observation is the association between serum DHEA
levels and increased longevity, a subject reviewed by Ohlsson et al., this issue.
Most importantly, a subject which remains to be supported by long-term clinical
trials but which shows very promising preclinical data is the possibility of a
beneficial effect of DHEA on brain functions, especially cognition, memory
and delayed development of mild cognitive impairment and Alzheimer’s
disease (see Starka et al.; Soma et al; Pluchino et al; Maggio et al.; Hill et al.,
this issue). The information summarized in the very up-to-date manuscripts
of this special JSBMB issue has the potential of opening the way to a prodrug
replacement therapy already well illustrated on the symptoms and signs of
vulvovaginal atrophy and sexual dysfunction (Archer, this issue). The
administration to sex steroid deficient women of an appropriate amount of
DHEA able to correct the symptoms of vulvovaginal atrophy (mostly estrogen-
sensitive) and sexual dysfunction (androgen-sensitive), and potentially, in the
future, other problems of menopause, does permit to the sex steroid-deficient
women to benefit from a normal/sufficient level of sex steroids in specific tissues
using the enzymes developed over 500 million years to permit a better quality
of life during the menopausal years.

Inactivation of androgens by UDP-glucuronosyltransferase enzymes in humans

Alain Belanger, Georges Pelletier, Fernand Labrie, Olivier Barbier and Sarah Chouinard
TRENDS in Endocrinology and Metabolism 2003; 14(10):473-78
http://dx.doi.org:/10.1016/j.tem.2003.10.005

In humans, 3b-hydroxysteroid dehydrogenase (3β-HSD), 17β-HSD and
5α-reductase activities in androgen target tissues, such as the prostate and
skin, convert dehydroepiandrosterone, androstenedione and testosterone into
the most potent natural androgen dihydrotestosterone (DHT). This androgen
is converted mainly in situ into two phase I metabolites, androsterone (ADT)
and androstane-3α,17β-diol (3α-DIOL), which might be back converted to DHT.
Here, we discuss the recent findings regarding the characterization of specific
UDP glucuronosyltransferases (UGTs), UGT2B7, B15 and B17, responsible for
the glucuronidation of these metabolites. The tissue distribution and cellular
localization of the UGT2B transcripts and proteins in humans clearly indicate
that these enzymes are synthesized in androgen-sensitive tissues. It is
postulated that the conjugating activity of UGT enzymes is the main mechanism
for modulating the action of steroids and protecting the androgen-sensitive
tissues from deleteriously high concentrations of DHT, ADT and 3α-DIOL.
Synthesis and Evaluation of Potential Radioligands for the Progesterone Receptor

R.M. Hoyte, W. Rosner, I.S. Johnson, J. Zielinski, and R. B. Hochberg
J. Med. Chem. 1985; 28: 1695-1699

Several steroidal analogues were synthesized as potential y-emitting radioligands
for the progesterone receptor. Each of these compounds was tested as an inhibitor
of the specific binding of [3H]-17α,21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione
(R5020) to the progesterone receptor in rabbit uterine cytosol. R5020 is a well-
known progestin with high affinity for the receptor. Of the compounds synthesized,
aromatic N-substituted (2-17 steroidal carboxamides inhibited the binding only
poorly. Three compounds, 16α-iodo-4-estren-17β-ol-3-one, 17α-[2(E)-iodovinyl]
-4-estren-17β-ol-3-one, and 17α-[2(Z)-iodovinyl]-4-estren-l7β-ol-3-one are
excellent competitors, each having a Ki less than or equal to that of the natural
progestin, progesterone. Since similar iodinated analogues of estrogens
have been shown to be extremely stable both in vivo and in vitro, these compounds
are potentially useful ligands for the progesterone receptor.

Estradiol concentration and the expression of estrogen receptors in the testes of
the domestic goose (Anser anser f. domestica) during the annual reproductive cycle

Leska, J. Kiezun, B. Kaminska, L. Dusza
Domestic Animal Endocrinology 51 (2015) 96–104
http://dx.doi.org/10.1016/j.domaniend.2014.12.002

Seasonal fluctuations in the activity of bird testes are regulated by a complex mechanism
where androgens play a key role. Until recently, the role played by estrogens in males has
been significantly underestimated. However, there is growing evidence that the proper
functioning of the testes is associated with optimal estradiol (E2) concentration
in both the plasma and testes of many mammalian species. Estrogens are
gradually emerging as very important players in hormonal regulation of
reproductive processes in male mammals. Despite the previously mentioned,
it should be noted that estrogenic action is limited by the availability of
specific receptors – estrogen receptor alpha (ERα) and estrogen receptor beta
(ERβ). Interestingly, there is a general scarcity of information concerning the
estrogen responsive system in the testes of male birds, which is of particular
interest in exploring the phenomenon of seasonality of reproduction. To address
this question, we have investigated for the first time the simultaneous
expression of testicular ERα and ERβ genes and proteins with the
accompanying plasma and testicular E2 concentrations during the annual
reproductive cycle of male bird. The research model was the domestic
goose (Anser anser f. domestica), a species whose annual reproductive
cycle can be divided into 3 distinct phases characterized by changes
in testicular activity. It has been revealed that the stable plasma E2 profile
did not correspond to changing intratesticular E2 profile throughout the
experiment. The expression of ERα and ERβ genes and proteins was detected
in gander testes and it fluctuated on a seasonal basis with lower level in
breeding and sexual reactivation stages and higher level during the
nonbreeding stage. Our results demonstrated changes in testicular sensitivity
to estrogens in male domestic goose during the annual reproductive cycle.
The seasonal pattern of estrogen receptors (ERs) expression was analyzed
against the hormonal background and a potential mechanism of ERs regulation
in bird testes was proposed. The present study revealed seasonal variations
in the estrogen responsive system, but further research is needed to fully
explore the role of estrogens in the reproductive tract of male birds.

Effects of 5α-dihydrotestosterone on expression of genes related to steroidogenesis
and spermatogenesis during the sex determination and differentiation periods of
the pejerrey, Odontesthes bonariensis

Anelisa González, Juan I. Fernandino, Gustavo M. Somoza
Comparative Biochemistry and Physiology, Part A 182 (2015) 1–7
http://dx.doi.org/10.1016/j.cbpa.2014.12.003

Sex steroid hormones are important players in the control of sex differentiation
by regulating gonadal development in teleosts. Although estrogens are clearly
associated with the ovarian differentiation in teleosts, the effects of androgens
on early gonadal development are still a matter of debate. Traditionally,
11-ketotestosterone (11-KT) is considered themajor androgen in fish; however,
5α-dihydrotestosterone (5α-DHT), the most potent androgen in tetrapods, was
recently found in fish testis and plasma, but its physiological role is still unknown.
In this context, the expression of genes associated with steroidogenesis and
spermatogenesis, body growth and sex differentiation were assessed in
Odontesthes bonariensis larvae fed with food supplemented with two doses of
5α-DHT (0.1 and 10 μg/g of food) from hatching to 6 weeks of age. At the lowest
dose, 5α-DHT treated larvae showed an estrogenic gene expression pattern, with
low hsd11β2 and high cyp19α1α and er2 expression levels with no differences
in sex ratio. At the highest dose, 5α-DHT produced a male-shifted sex ratio and
the larvae exhibited a gene expression profile characteristic of an advancement
of spermatogenesis, with inhibition of amh and stimulation of ndrg3. No
differences were observed in somatic growth. These results suggest that in
this species, 5α-DHT could have a role on sex differentiation and its effects
can differ according to the dose.
Do androgens link morphology and behavior to produce phenotype-specific
behavioral strategies?

Douglas G. Barron, Michael S. Webster, Hubert Schwabl
Animal Behaviour 100 (2015) 116e124
http://dx.doi.org/10.1016/j.anbehav.2014.11.016

Morphological and behavioral traits often covary with each other, and the links
between them may arise from shared physiological mechanisms. In particular,
androgens such as testosterone have emerged as prime candidates for linking
behaviour and morphology due to the environmental sensitivity and pleiotropic
effects of these hormones. In this study we investigated the hypothesis that
androgens simultaneously relate to morphological and behavioral variation,
thereby producing the integrated reproductive phenotypes of male red-backed
fairy-wrens, Malurus melanocephalus. Males of this species can adopt one of
three discrete breeding phenotypes: breeding in red/black plumage, breeding
in brown plumage, or remaining as nonbreeding brown natal auxiliaries. Although
the expression of morphological traits in this species is regulated by androgens
and phenotypes differ in baseline androgen levels (red/black breeder > brown
breeder > auxiliary), injection with GnRH failed to expose phenotype specific
constraints on androgen production. Observations of territoriality, nestling
feeding and extraterritorial forays revealed phenotype-specific patterns of mating
and parental effort, yet these were largely related to age and were not correlated
with baseline or GnRH-induced androgen levels, or the androgen change between
these points. While these findings support the idea that morphological and
behavioral traits are linked via phenotypic correlations, they do not support
the hypothesis that behavioral differences arise from variation in circulating
androgens or the capacity to produce them.
Effects of sex steroids on expression of genes regulating growth-related
mechanisms in rainbow trout (Oncorhynchus mykiss)

Beth M. Cleveland, Gregory M. Weber
General and Comparative Endocrinology xxx (2015) xxx–xxx
http://dx.doi.org/10.1016/j.ygcen.2014.11.018

Effects of a single injection of 17b-estradiol (E2), testosterone (T), or
5b-dihydrotestosterone (DHT) on expression of genes central to the
growth hormone (GH)/insulin-like growth factor (IGF) axis, muscle
regulatory factors, transforming growth factor-beta (TGFβ) superfamily
signaling cascade, and estrogen receptors were determined in rainbow
trout (Oncorhynchus mykiss) liver and white muscle tissue. In liver in
addition to regulating GH sensitivity and IGF production, sex
steroids also affected expression of IGF binding proteins, as E2, T,
and DHT increased expression of igfbp2β and E2 also increased
expression of igfbp2 and igfbp4. Regulation of this system also occurred
in white muscle in which E2 increased expression of igf1, igf2, and
igfbp5β1, suggesting anabolic capacity may be maintained in white
muscle in the presence of E2. In contrast, DHT decreased expression
of igfbp5β1. DHT and T decreased expression of myogenin, while other
muscle regulatory factors were either not affected or responded similarly
for all steroid treatments. Genes within the TGFβ superfamily signaling
cascade responded to steroid treatment in both liver and muscle,
suggesting a regulatory role for sex steroids in the ability to transmit
signals initiated by TGFβ superfamily ligands, with a greater number
of genes responding in liver than in muscle. Estrogen receptors were
also regulated by sex steroids, with era1 expression increasing for all
treatments in muscle, but only E2- and T-treatment in liver. E2 reduced
expression of erb2 in liver. Collectively, these data identify how
physiological mechanisms are regulated by sex steroids in a manner
that promotes the disparate effects of androgens and estrogens on
growth in salmonids.
Distribution and function of 3′,5′-Cyclic-AMP phosphodiesterases in the human ovary

T.S. Petersen, S.G. Kristensen, J.V. Jeppesen, .., K.T. Macklon, C.Y. Andersen
Molecular and Cellular Endocrinology 403 (2015) 10–20
http://dx.doi.org/10.1016/j.mce.2015.01.004

The concentration of the important second messenger cAMP is regulated by
phosphodiesterases (PDEs) and hence an attractive drug target. However,
limited human data are available about the PDEs in the ovary. The aim of the
present study was to describe and characterise the PDEs in the human ovary.
Results were obtained by analysis of mRNA microarray data from follicles and
granulosa cells (GCs), combined RT-PCR and enzymatic activity analysis in GCs,
immunohisto-chemical analysis of ovarian sections and by studying the effect
of PDE inhibitors on progesterone production from cultured GCs. We found that
PDE3, PDE4, PDE7 and PDE8 are the major families present while PDE11A
was not detected. PDE8B was differentially expressed during folliculogenesis.
In cultured GCs, inhibition of PDE7 and PDE8 increased basal progesterone
secretion while PDE4 inhibition increased forskolin-stimulated progesterone
secretion. In conclusion, we identified PDE3, PDE4, PDE7 and PDE8 as
the major PDEs in the human ovary.
Diethylstilbestrol can effectively accelerate estradiol-17-O-glucuronidation, while
potently inhibiting estradiol-3-O-glucuronidation

Liangliang Zhu, Ling Xiao, Yangliu Xia, .., Yan Wu, Ganlin Wu, Ling Yang
Toxicology and Applied Pharmacology 283 (2015) 109–116
http://dx.doi.org/10.1016/j.taap.2015.01.003

This in vitro study investigates the effects of diethylstilbestrol (DES), a widely
used toxic synthetic estrogen, on estradiol-3- and 17-O- (E2-3/17-O)
glucuronidation, via culturing human liver microsomes (HLMs) or
recombinant UDP-glucuronosyl-transferases (UGTs) with DES and E2.
DES can potently inhibit E2-3-O-glucuronid-ation in HLM, a probe reaction
for UGT1A1. Kinetic assays indicate that the inhibition follows a competitive
inhibition mechanism, with the Ki value of 2.1 ± 0.3 μM, which is less than
the possible in vivo level. In contrast to the inhibition on E2-3-O-glucuronidation,
the acceleration is observed on E2-17-O-glucuronidation in HLM, in which
cholestatic E2-17-O-glucuronide is generated. In the presence of DES
(0–6.25 μM), Km values for E2-17-Oglucuronidation are located in the
range of 7.2–7.4 μM, while Vmax values range from 0.38 to 1.54 nmol/min/mg.
The mechanism behind the activation in HLM is further demonstrated by
the fact that DES can efficiently elevate the activity of UGT1A4 in catalyzing
E2-17-O-glucuronidation. The presence of DES (2 μM) can elevate Vmax from
0.016 to 0.81 nmol/min/mg, while lifting Km in a much lesser extent from 4.4 to
11 μM. Activation of E2-17-O-glucuronidation is well described by a two binding
site model, with KA, α, and β values of 0.077 ± 0.18 μM, 3.3 ± 1.1 and 104 ± 56,
respectively. However, diverse effects of DES towards E2-3/17-O-glucuronidation
are not observed in liver microsomes from several common experimental animals.
In summary, this study issues new potential toxic mechanisms for DES: potently
inhibiting the activity of UGT1A1 and powerfully accelerating the formation of
cholestatic E2-17-O-glucuronide by UGT1A4.
Dehydroepiandrosterone: A neuroactive steroid

Luboslav Stárka, Michaela Dusková, Martin Hill
Journal of Steroid Biochemistry & Molecular Biology 145 (2015) 254–260
http://dx.doi.org/10.1016/j.jsbmb.2014.03.008

Dehydroepiandrosterone (DHEA) and its sulfate bound form (DHEAS) are important
steroids of mainly adrenal origin. They are produced also in gonads and in the brain.
Dehydroepiandrosterone easily crosses the brain–blood barrier and in part is also
produced locally in the brain tissue. In the brain, DHEA exerts its effects after
conversion to either testosterone and dihydrotestosterone or estradiol via androgen
and estrogen receptors present in the most parts of the human brain, through
mainly non-genomic mechanisms, or eventually indirectly via the effects of its
metabolites formed locally in the brain. As a neuroactive hormone, DHEA in
cooperation with other hormones and transmitters significantly affects some
aspects of human mood, and modifies some features of human emotions and
behavior. It has been reported that its administration can increase feelings of well-
being and is useful in ameliorating atypical depressive disorders. It has
neuroprotective and antiglucocorticoid activity and modifies immune reactions,
and some authors have also reported its role in degenerative brain diseases.
Here we present a short overview of the possible actions of dehydroepiandrosterone
and its sulfate in the brain, calling attention to various mechanisms of their action
as neurosteroids and to prospects for the knowledge of their role in brain disorders.
Androgens and mammalian male reproductive tract development

Aki Murashima, Satoshi Kishigami, Axel Thomson, Gen Yamada
Biochimica et Biophysica Acta 1849 (2015) 163–170
http://dx.doi.org/10.1016/j.bbagrm.2014.05.020

One of the main functions of androgen is in the sexually dimorphic development of
the male reproductive tissues. During embryogenesis, androgen determines the
morphogenesis of male specific organs, such as the epididymis, seminal vesicle,
prostate and penis. Despite the critical function of androgens in masculinization,
the downstream molecular mechanisms of androgen signaling are poorly
understood. Tissue recombination experiments and tissue specific androgen
receptor (AR) knockout mouse studies have revealed epithelial or mesenchymal
specific androgen-AR signaling functions. These findings also indicate that
epithelial–mesenchymal interactions are a key feature of AR specific activity,
and paracrine growth factor action may mediate some of the effects of androgens.
This review focuses on mouse models showing the interactions of androgen and
growth factor pathways that promote the sexual differentiation of reproductive organs.
Recent studies investigating context dependent AR target genes are also discussed.
This article is part of a Special Issue entitled: Nuclear receptors in animal development.

All sex steroids are made intracellularly in peripheral tissues by the mechanisms of
intracrinology after menopause

Fernand Labrie
Journal of Steroid Biochemistry & Molecular Biology 145 (2015) 133–138
http://dx.doi.org/10.1016/j.jsbmb.2014.06.001

Following the arrest of estradiol secretion by the ovaries at menopause, all estrogens
and all androgens in postmenopausal women are made locally in peripheral target
tissues according to the physiological mechanisms of intracrinology. The locally
made sex steroids exert their action and are inactivated intracellularly without
biologically significant release of the active sex steroids in the circulation.The
level of expression of the steroid-forming and steroid-inactivating enzymes is
specific to each cell type in each tissue, thus permitting to each cell/tissue to
synthesize a small amount of androgens and/or estrogens in order to meet the
local physiological needs without affecting the other tissues of the organism.
Achieved after 500 million years of evolution, combination of the arrest of ovarian
estrogen secretion, the availability of high circulating levels of DHEA and the
expression of the peripheral sex steroid-forming enzymes have permitted the
appearance of menopause with a continuing access to intra-tissular sex steroids
for the individual cells/tissues without systemic exposure to circulating estradiol.
In fact, one essential condition of menopause is to maintain serum estradiol at
biologically inactive (subthreshold) concentrations, thus avoiding stimulation of the
endometrium and risk of endometrial cancer. Measurement of the low levels of
serum estrogens and androgens in postmenopausal women absolutely requires
the use of MS/MS-based technology in order to obtain reliable accurate, specific
and precise assays. While the activity of the series of steroidogenic enzymes can
vary, the serum levels of DHEA show large individual variations going from barely
detectable to practically normal “premenopausal” values, thus explaining the
absence of menopausal symptoms in about 25% of women. It should be added
that the intracrine system has no feedback elements to adjust the serum levels
of DHEA, thus meaning that women with low DHEA activity will not be improved
without external supplementation. Exogenous DHEA, however, follows the same
intracrine rules as described for endogenous DHEA, thus maintaining serum
estrogen levels at subthreshold or biologically inactive concentrations. Such blood
concentrations are not different from those observed in normal postmenopausal
women having high serum DHEA concentrations. Androgens, on the other hand,
are practically all made intracellularly from DHEA by the mechanisms of intracrinology
and are always maintained at very low levels in the blood in both pre- and
postmenopausal women. Proof of the importance of intracrinology is also provided,
among others, by the well-recognized benefits of aromatase inhibitors and
anti-estrogens used successfully for the treatment of breast cancer in
postmenopausal women where all estrogens are made locally. Each medical
indication for the use of DHEA, however, requires clinical trials performed
according to the FDA guidelines and the best rules of clinical medicine.
A multi-step, dynamic allosteric model of testosterone’s binding to sex hormone
binding globulin

Mikhail N. Zakharov, Shalender Bhasin, Thomas G. Travison, Ran Xue, et al.
Molecular and Cellular Endocrinology 399 (2015) 190–200
http://dx.doi.org/10.1016/j.mce.2014.09.001

Purpose: Circulating free testosterone (FT) levels have been used widely in the
diagnosis and treatment of hypogonadism in men. Due to experimental
complexities in FT measurements, the Endocrine Society has recommended
the use of calculated FT (cFT) as an appropriate approach for estimating FT.
We show here that the prevailing model of testosterone’s binding to SHBG,
which assumes that each SHBG dimer binds two testosterone molecules
and that the two binding sites on SHBG have similar binding affinity is
erroneous and provides FT values that differ substantially from those
obtained using equilibrium dialysis.
Methods: We characterized testosterone’s binding to SHBG using
binding isotherms, ligand depletion curves, and isothermal titration
calorimetry (ITC). We derived a new model of testosterone’s binding to
SHBG from these experimental data and used this model to determine
FT concentrations and compare these values with those derived from
equilibrium dialysis.
Results: Experimental data on testosterone’s association with SHBG
generated using binding isotherms including equilibrium binding, ligand
depletion experiments, and ITC provide evidence of a multi-step dynamic
process, encompassing at least two inter-converting microstates in unliganded
SHBG, readjustment of equilibria between unliganded states upon binding
of the first ligand molecule, and allosteric interaction between two binding
sites of SHBG dimer. FT concentrations in men determined using the new
multistep dynamic model with complex allostery did not differ from those
measured using equilibrium dialysis. Systematic error in calculated FT
vales in females using Vermeulen’s model was also significantly reduced.
In European Male Aging Study, the men deemed to have low FT (<2.5th
percentile) by the new model were at increased risk of sexual symptoms
and elevated LH.
Conclusion: Testosterone’s binding to SHBG is a multi-step dynamic
process that involves complex allostery within SHBG dimer. FT values
obtained using the new model have close correspondence with those
measured using equilibrium dialysis.

Cohesin modulates transcription of estrogen-responsive genes

Jisha Antony, Tanushree Dasgupta, Jenny M. Rhodes, Miranda V. McEwan, et al.
Biochimica et Biophysica Acta 1849 (2015) 257–269
http://dx.doi.org/10.1016/j.bbagrm.2014.12.011

The cohesin complex has essential roles in cell division, DNA damage repair
and gene transcription. The transcriptional function of cohesin is thought to
derive from its ability to connect distant regulatory elements with gene promoters.
Genome-wide binding of cohesin in breast cancer cells frequently coincides
with estrogen receptor alpha (ERα), leading to the hypothesis that cohesin
facilitates estrogen-dependent gene transcription. We found that cohesin
modulates the expression of only a subset of genes in the ER transcription
program, either activating or repressing transcription depending on the gene
target. Estrogen-responsive genes most significantly influenced by cohesin
were enriched in pathways associated with breast cancer progression such
as PI3K and ErbB1. In MCF7 breast cancer cells, cohesin depletion enhanced
transcription of TFF1 and TFF2, and was associated with increased ER binding
and increased interaction between TFF1 and its distal enhancer situated
within TMPRSS3. In contrast, cohesin depletion reduced c-MYC mRNA and
was accompanied by reduced interaction between a distal enhancer of c-MYC
and its promoters. Our data indicates that cohesin is not a universal facilitator
of ER-induced transcription and can even restrict enhancer–promoter communication.
We propose that cohesion modulates transcription of estrogen-dependent genes
to achieve appropriate directionality and amplitude of expression.
Angiogenesis in Breast Cancer and its Correlation with Estrogen, Progesterone
Receptors and other Prognostic Factors

Jyotsna Naresh Bharti, Poonam Rani, Vinay Kamal, Prem Narayan Agarwal
Journal of Clinical and Diagnostic Research. 2015 Jan, Vol-9(1): EC05-EC07
http://dx.doi.org:/10.7860/JCDR/2015/10591.5447

Purpose: The  aim  of  study  is  to  evaluate  angiogenesis using  CD34,  in
estrogen,  progesterone  positive  and  negative breast cancer  and  to  correlate
the  microvessel  density  with known  histological  prognostic  factors,
morphological  type  of breast carcinoma and lymph node metastasis.
Materials and Methods: Twenty eight untreated cases of breast cancer were
included  in  the  study  and  paraffin  embedded  sections  were  obtained
from  representative  mastectomy specimen of breast cancer patient. The sections
were stained with hematoxylin and eosin stain and immunohistochemistry was
performed using CD34, estrogen, progesterone, cytokeratin and epithelial
membrane antigen  antibody.  Angiogenesis was analyzed using CD 34 antibody.
For statistical analysis, cases were grouped into estrogen, progesterone positive
and negative receptors.
Results: Mean microvessel density in ER-/PR-, ER-/ PR+, ER+/PR-, ER+/PR+
was 15.45, 14.83, 11, 10.89 respectively.  A significant correlation was found
between ER receptors and mean vascular density with p-value (< 0.05).
A significant difference was observed in mean vascular density between
the four groups comprising (p-value < 0.05).  Infiltrating duct carcinoma
(NOS) grade III has got the highest mean microvessel density (14.17)
followed by grade II (12.93) and grade I (12.33).
Conclusion: Information about prognostic factors in breast cancer
patients may lead to better ways to identify those patients at high risk
who might benefit from adjuvant therapies.

Combined blockade of testicular and locally made androgens in prostate cancer:
A highly significant medical progress based upon intracrinology

Fernand Labrie
Journal of Steroid Biochemistry & Molecular Biology 145 (2015) 144–156
http://dx.doi.org/10.1016/j.jsbmb.2014.05.012

Recently two drugs, namely the antiandrogen MDV-3100 and the inhibitor
of 17β-hydroxylase abiraterone have been accepted by the FDA for the
treatment of castration-resistant prostate cancer (CRPC) with or without
previous chemotherapy, with a prolongation of overall survival of 2.2–4.8months.
While medical (GnRH agonist) or surgical castration reduces the serum levels
of testosterone by about 97%, an important concentration of testosterone and
dihydrotestosterone remains in the prostate and activates the androgen receptor
(AR), thus offering an explanation for the positive data obtained in CRPC. In fact,
explanation of the response observed with MDV-3100 or enzalutamide in CRPC
is essentially a blockade of the action or formation of intraprostatic androgens.
In addition to the inhibition of the action or formation of androgens made locally
by the mechanisms of intracrinology, increased AR levels and AR mutations can
be involved, especially in very advanced disease.

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Endothelial Dysfunction (release into the circulation of damaged endothelial cells) as A Risk Marker for Ischemia and MI

Reporter and Curator: Larry H Bernstein, MD, FCAP

Endothelial Dysfunction: An Early Cardiovascular Risk Marker in Asymptomatic Obese Individuals with Prediabete

AK Gupta, E Ravussin, DL Johannsen, AJ Stull,WT.Cefalu and WD Johnson at Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA Brit J Med & Med Res 2012; 2(3):413-423 [www.ScienceDomain.org]

provides an exceedingly interesting insight into the relationship between type 2 diabetes mellitus, obesity and risk for cardiovascular disease in patients who are asymptomatic prediabetics, defined as a fasting blood glucose between 1000 and 1240 mg/L, or a Hb A1c (may not accurate for African Americans) between 5.6 and 6.5.  They would be expected to show an abnormal 5-hr GTT.

Obesity is associated with the release from adipocytes of adiponectin, which it has been reported is countered by resistin.  We might also have the effect of the insulin secreting beta cell, that releases insulin without a relationship to an anabolic function, through IGF-1 related to feedback to the pituitary GH, which takes a dominant catabolic role. Thus, insulin resistance. This is an oversimplification, and far greater depth is found elsewhere.

This study is consistent with another study on  Metabolism Influences Cancer

Reuben Shaw, Ph.D., a geneticist and researcher at the Salk Institute: Metabolism Influences Cancer

Recent development on Human Stem Cell Therapies for comorbidity and Cardiovascular disease

Human Stem Cell Therapies: UCSD New Discovery addressing the Limiting Factor and Providing the Solution

https://pharmaceuticalintelligence.com/2014/01/06/human-stem-cell-therapies-ucsd-new-discovery-addressing-the-limiting-factor-and-providing-the-solution/

This study reported a potential early marker of myocardial infarction by the release into the circulation of damaged endothelial cells that are to be measured in patients suspected of severe ischemia in a clinical trial.  The question that I raised in my comment was whether this would have to be a special immunochemical assay of tagged cells, and if that were the case, would it be measured on an automated flow-based hemocytometer, which can differentiate several populations of cells – granulocytes, lymphocytes, red cells, platelets, immature granuloytes, BLASTS.  That would be a very practical extension of the technology for labs worldwide.

Abstract

Aims: To elucidate if endothelial dysfunction is an early CV risk marker in obese men and women with prediabetes.
Study Design: Cross-sectional study.

Place and Duration of Study: Clinical Research Unit, Pennington Biomedical Research Center, Baton Rouge, LA. United States.

Background: Overweight and obese status denotes an increasing adipose tissue burden which spills over into ectopic locations, including the visceral compartment, muscle and liver. Associated co-morbidities enhance cardiovascular (CV) risk. Endothelium which is the largest receptor-effector end-organ in our bodies, while responding to numerous physical and chemical stimuli maintains vascular homeostasis. Endothelial dysfunction (ED) is the initial perturbation, which precedes fatty streak known to initiate atherosclerosis: insidious process which often culminates as sudden catastrophic CV adverse event.

Methodology:  Asymptomatic men and women; [n=42] coming in after an overnight fast had demographic, anthropometric, clinical chemistry and

  • resting endothelial function (EF)
  • increased test finger peripheral arterial tone (PAT) relative to control;
    • expressed as relative hyperemia index (RHI)] assessments.

Results: Adults with desirable weight [n=12] and overweight [n=8] state, had normal fasting plasma glucose [Mean(SD)]: FPG [91.1(4.5), 94.8(5.8) mg/dL], insulin [INS, 2.3(4.4), 3.1(4.8) µU/ml], insulin sensitivity by homeostasis model assessment [HOMA-IR, 0.62(1.2), 0.80(1.2)] and desirable resting clinic blood pressure [SBP/DBP, 118(12)/74(5), 118(13)/76(8) mmHg].

Obese adults [n=22] had

  • prediabetes [FPG, 106.5(3.5) g/dL],
  • hyperinsulinemia [INS 18.0(5.2) µU/ml],
  • insulin resistance [HOMA-IR .59(2.3)],
  • prehypertension [PreHTN; SBP/DBP 127(13)/81(7) mmHg] and
  • endothelial dysfunction [ED;
  • reduced RHI 1.7(0.3) vs. 2.4(0.3); all p<0.05].

Age-adjusted RHI correlated with BMI [r=-0.53; p<0.001]; however,

    • BMI-adjusted RHI was not correlated with age [r=-0.01; p=0.89].

Conclusion: Endothelial dysfunction reflective of cardiometabolic changes in obese adults can be an early risk marker for catastrophic CV events.

Keywords: Fasting plasma glucose; healthy adults; reverse cholesterol transport pathway; insulin resistance; body weight; relative hyperemia index.

ABBREVIATIONS

ADA: American Diabetes association; BMI: body mass index; CVD: cardiovascular disease; CV: cardiovascular; DBP: diastolic blood pressure; ED: endothelial dysfunction; EF: resting endothelial function; FPG: fasting plasma glucose; HOMA-IR: homeostasis model assessment; INS: insulin; JNC 7: Joint National Commission 7; LDL-C/HDL-C: low density lipoprotein cholesterol to high density lipoprotein; NCEP ATP III: National Cholesterol Education Program Adult Treatment Panel III; PAT: peripheral arterial tone; PreDM: prediabetes; PreHTN: prehypertension; PBRC: Pennington Biomedical Research Center; RHI: relative hyperemia index; SBP: systolic blood pressure; Total-C/HDL-C: total cholesterol to high density lipoprotein cholestrol; TG/HDL-C: triglycerides to high density lipoprotein cholesterol; WC: waist circumference.

Introduction

Healthy adults with no chronic medical conditions, on no prescription medications (n=24) and with low cardiovascular risk, in a randomized-order, cross-over clinical trial, with a 2 week washout period, exhibitd improved endothelial function (measured with flow mediated dilatation) with a diet rich in antioxidants (Franzini et al., 2012). Healthy over weight and obese volunteers with normal glucose appear to attenuate flow mediated dilation after high
glycemic index carbohydrate meals (Suessenbacher et al., 2011). In matched (age, work place, physical activity, tobacco use, blood pressure, serum lipids and family history of premature coronary artery disease) male shift and no shift workers, peripheral endothelial function (peripheral arterial tone (PAT) index obtained with the EndoPAT technique) was impaired in shift workers, suggesting elevated cardiovascular risk (Lavi et al., 2009).

Endothelial function thus appears to be an exquisitely sensitive marker for a variety of populations, under various conditions. Although endothelial function has been evaluated in numerous disease conditions and perturbed with a variety of agents, there has, to our knowledge, not been a comparison of resting endothelial function in free living healthy lean, overweight and obese subjects. Using a noninvasive assessment for resting endothelial function (by measuring the peripheral arterial tone, Bonetti et al., 2004), we tested the hypothesis that fasting glucose escalation in otherwise asymptomatic obese men and women is functionally reflected as endothelial dysfunction.

Endothelial Function

Assessment of resting endothelial function was done with the participant in fasting state, after having avoided stimulants (caffeine, tobacco, alcohol, exercise) for 12 hours, at the same fixed clock hour (range 8-10 AM), using the EndoPAT 2000 device manufactured by ITAMAR Medical®. This assessment technique has been previously validated (Bonetti et al., 2004), has been used in numerous (>250) peer reviewed publications (Carty et al., 2012; Kuvin et al., 2003) and has been in routine use in our clinical core. Briefly: subjects coming
in from home, after an overnight fast and having avoided stimulants for 12-hours, were placed in a supine position for 20 minutes in a quiet room before the test. A patented single use finger sleeve was then placed on the index finger of each hand to continuously measure peripheral arterial tone. A blood pressure cuff applied to the upper arm of the non-dominant arm (test arm) was then used to occlude the brachial artery for 5 minutes. This was followed by a rapid release. The dominant arm without any manipulation served as the control. The
built in, validated software integrated the data gathered from the finger sleeves of the control (undisturbed) and the test arms (during the baseline, occlusion and release phases), thus providing the relative hyperemia index (RHI) for the test arm. This flow mediated dilatation induced change in the test arm, relative to the control arm, served as the measure for endothelial function (RHI).

The subjects with desirable and overweight body weight were significantly younger [36.7(19.1) and 27.4(3.9) years, respectively], than those who were obese [53.2(11.6) years]. We performed correlations between the measure for endothelial function (RHI) and confounding factors like BMI, age and gender. Age-adjusted RHI correlated with BMI [r=- 0.53, p<0.001]; however, BMI-adjusted RHI was not associated with age [r=-0.01, p=0.89]. Fig. 1 depicts panels for the regression line for RHI as a function of age, (and BMI, glucose
and HOMA-IR, respectively) superimposed on a scatter plot. No correlation was observed between endothelial function and age (r²=0.07), while endothelial function was highly correlated with body mass index, glucose and insulin sensitivity (r²=0.3).

DISCUSSION

Asymptomatic obese adults with prediabetes (when compared to asymptomatic desirable weight and overweight adults with normal glucose), exhibit above the upper limits for desirable fasting plasma total cholesterol (>200mg/dL) and triglycerides (>150 mg/dL), but due to a relatively lower HDL-C display higher cardiac risk ratios (Total-C/HDL-C; p=0.05 and TG/HDL-C; p=0.02). A lower HDL-C and the elevated cardiac risk ratios are early clinical indicators for an impaired reverse cholesterol transport (RCT) pathway, a process by which cholesterol from the periphery is transported to the liver (Tall, 1998). The RCT pathway has been shown to be a sensitive indicator of the net flux (deposition vs. removal) of cholesterol homeostasis at the endothelium (Gupta et al., 1993; Tall et al., 2000). It is at the endothelium that the first fatty streaks, which over time deteriorate into atherosclerosis, have been shown to develop (Rosenfeld et al., 2000).

Impaired endothelial dysfunction is the first step in the process of atherosclerosis, even before the development of the fatty streak (Davignon, 2004; Ross 1999). These healthy obese men and women with prediabetes, prehypertension and impaired reverse cholesterol transport pathway were assessed to have impaired resting endothelial function, which is consistent with latent early onset cardiovascular disease.

We have demonstrated a high prevalence of isolated prediabetes or prehypertension and co-existing prediabetes and prehypertension, among the otherwise healthy US adults (Gupta et al., 2011). We have also elucidated that asymptomatic obese adults with overly heightened systemic inflammation, tend to have prediabetes and prehypertension (Gupta et al., 2010a). These individuals by various conventional measures (larger waist circumference, exacerbated systemic inflammation, higher insulin resistance, elevated triglycerides, lower high-density lipoprotein cholesterol, above average cardiac risk ratios and a significant co-existence of two or three concomitant metabolic risk factors) appear to be on an accelerated pathway towards early adverse cardiovascular events (Gupta et al., 2010a, 2010b). With this study we provide a dynamic, non-invasive, functional correlate: significant resting endothelial dysfunction, as an early biomarker for pre-atherosclerosis in obese adults with prediabetes.

Increased organ ectopic adipose burden especially in the muscle and liver appears to drive clinically recognizable adverse cardio metabolic changes (Hamdy et al., 2006). Increased inflammation (local and systemic) along with enhanced insulin resistance (liver, muscle) manifests as dysglycemia, dyslipidemia, excess reactive oxygen species, hyper-coagulablility and loss of blood pressure control (Gastaldelli et al., 2010).

We demonstrate an early impairment in the reverse cholesterol transport pathway, indicating a net deposition versus removal of cholesterol at the endothelium. In asymptomatic obese men and women with predisease  conditions (prediabetes and prehypertension) when contrasted with ideal bodyweight or overweight adults with normoglycemia and normal blood pressure, resting endothelial dysfunction can be an early warning sign for future catastrophic cardiovascular adverse events.

© 2012 Gupta et al.; This is an Open Access article distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

REFERENCES on circulating Endothelial Progenitor Cells as Biomarkers for Cardiovascular Disease and their Angiogenesis Potential.

Asahara T, Murohara T, Sullivan A, et al. Isolation of putative progenitor endothelial cells for angiogenesis. Science 1997;275:964-967.

Takahashi T, Kalka C, Masuda H, et al. Ischemia- and cytokine-induced mobilization of bone marrow-derived endothelial progenitor cells for neovascularization. Nat Med 1999;5:434-438.

Kocher AA, Schuster MD, Szabolcs MJ, et al. Neovascularization of ischemic myocardium by human bone-marrow-derived angioblasts prevents cardiomyocyte apoptosis, reduces remodeling and improves cardiac function. Nat Med 2001;7:430-436.

Rauscher FM, Goldschmidt-Clermont PJ, Davis BH, et al. Aging, progenitor cell exhaustion, and atherosclerosis. Circulation 2003;108:457-463.

Hill JM, Zalos G, Halcox JPJ, et al. Circulating endothelial progenitor cells, vascular function, and cardiovascular risk. N Engl J Med 2003;348:593-600.

Vasa M, Fichtlscherer S, Adler K, et al. Increase in circulating endothelial progenitor cells by statin therapy in patients with stable coronary artery disease. Circulation 2001;103:2885-2890

Laufs U, Werner N, Link A, et al. Physical training increases endothelial progenitor cells, inhibits neointima formation, and enhances angiogenesis. Circulation 2004;109:220-226.

Werner N, Kosiol S, Schiegl T, et al. Circulating endothelial progenitor cells and cardiovascular outcomes. N Engl J Med 2005;353:999-1007.

Aicher A, Heeschen C, Mildner-Rihm C, et al. Essential role of endothelial nitric oxide synthase for mobilization of stem and progenitor cells. Nat Med 2003;9:1370-1376.

Wollert KC, Meyer GP, Lotz J, et al. Intracoronary autologous bone-marrow cell transfer after myocardial infarction: the BOOST randomised controlled clinical trial. Lancet 2004;364:141-148.

Zhang H, Vakil V, Braunstein M, et al. Circulating endothelial progenitor cells in multiple myeloma: implications and significance. Blood 2005;105:3286-3294

Lyden D, Hattori K, Dias S, et al. Impaired recruitment of bone-marrow-derived endothelial and hematopoietic precursor cells blocks tumor angiogenesis and growth. Nat Med 2001;7:1194-1201.

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Triggering of Plaque Disruption and Arterial Thrombosis

Curator and Reporter: Larry H Bernstein, MD, FCAP

 

This discussion is a very interesting experimental model for the elucidation of plaque rupture in acute coronary syndromes.  The knowledge exists that there is a series of steps in develoiping atheromatous plaque.  We also know that platelets and endothelium are the location of this pathological development.  We don’t know exactly the role or mechanism of the contribution of hyperlipidemia, and what triggers plaque rupture.  This work reported is an experimental rabbit model that sheds light on the triggering of plaque rupture.

Triggering of Plaque Disruption and Arterial Thrombosis in an Atherosclerotic Rabbit Model

George S. Abela, MD, MSc; Paulo D. Picon, MD, MSc; Stephan E. Friedl, MEE; Otavio C. Gebara, MD; Akira Miyamoto, MD; Micheline Federman, PhD; Geoffrey H. Tofler, MB; James E. Muller, MD
From the Institute for Prevention of Cardiovascular Disease, Cardiovascular Division (G.S.A., S.E.F., G.H.T., J.E.M.), and the Department of Pathology (C.S.A., M.F.), Deaconess Hospital, Harvard Medical School, Boston, Mass; the Department of Pharmacology, Federal University and University of Passo Fundo (P.D.P.), Rio Grande de Sul, Brazil; the Heart Institute, University of São Paulo (O.C.G.), São Paulo, Brazil; and the First Department of Internal Medicine, National Defense Medical College (A.K.), Saitama, Japan.

Abstract

Background

It is now recognized that plaque disruption and thrombosis, a process often triggered by activities of the patient, is generally the cause of the onset of acute coronary syndromes. Understanding of disease onset could be greatly enhanced by the availability of a suitable animal model of plaque disruption and thrombosis. The aim of this study was to replicate and further characterize an atherosclerotic rabbit model of triggering of arterial thrombosis that was introduced by Constantinides and Chakravarti more than 30 years ago but not subsequently used.

  • Aortic plaques were induced by a high-cholesterol diet, by mechanical balloon injury of the artery, or by a combination of the two.
  • Triggering was attempted by injection of Russell’s viper venom (RVV), which is a proteolytic procoagulant, and histamine.

 Methods and Results

A total of 53 New Zealand White rabbits were exposed to one of four preparatory regimens:

  1. rabbits in group I (n=9) were fed a regular diet for 8 months;
  2. rabbits in group II (n=13) were fed a diet of 1% cholesterol for 2 months alternated with 2 months of a regular diet for a total of 8 months;
  3. rabbits in group III (n=5) underwent balloon-induced arterial wall injury, then were given a regular diet for 8 months; and
  4. rabbits in group IV (n=14) underwent balloon-induced arterial wall injury, then were given a diet of 1% cholesterol for 2 months followed by a regular diet for 2 months for a total of 4 months. After completion of the preparatory regimen, triggering of plaque disruption and thrombosis was attempted by injection of RVV (0.15 mg/kg IP) and histamine (0.02 mg/kg IV).
  • In group I, normal control rabbits without atherosclerosis, only one small thrombus was noted in 1 of 9 rabbits.
  • In group II, cholesterol-fed rabbits, thrombosis occurred in 3 of 13 rabbits.
  • Thrombus occurred in all rabbits in group III (5 of 5) and in 10 of 14 rabbits in group IV.
Although the frequency of thrombosis was not significantly different between groups I and II, possibly due to a small sample size, it was significantly different among all four groups (P<.001). Also, the frequency and amount of thrombus formation were significantly different among all four groups (P<.001; P<.0001) but not between groups I and II. Rabbits with atherosclerosis (those in groups II and IV) demonstrated plaque disruption and overlying platelet-rich thrombus formation similar to that observed in patients with acute coronary syndromes. The surface area covered by thrombus was
  1. 2 mm^2 in group I, 1
  2. 5.3±19.2 mm^2 in group II,
  3. 223±119 mm^2 in group III, and
  4. 263±222 mm^2 in group IV.
Rabbits in groups III and IV had the greatest amount of thrombus, and this amount was significantly greater than in rabbits in groups I and II (P<.001 and P<.03, respectively).

Conclusions

A suitable animal model is available for the study of plaque disruption and arterial thrombosis.

  • Hypercholesterolemia and mechanical arterial wall injury seemed to produce plaques vulnerable to triggering of disruption and thrombosis, whereas
  • normal arteries were relatively resistant to triggering.
This model provides a method to evaluate agents that might decrease the occurrence of vulnerable plaques or the amount of thrombus formed after triggering. Most important, the model can be used to identify the features of vulnerable plaques and the pharmacological stressors that trigger plaque disruption and thrombus formation.

Key Words: thrombosis, atherosclerosis, balloon, histamine, RVV

Introduction

Plaque disruption and subsequent arterial thrombosis are now recognized as critical to the onset of acute coronary ischemic syndromes. It is hypothesized that occurrence of thrombotic coronary occlusion has three components.
  1. First, a plaque that is vulnerable to disruption must be present.
  2. Second, acute physiological events are required to induce plaque disruption and thrombosis.
  3. Third, a relatively hypercoagulable state and heightened vasomotor tone increase the likelihood that arterial thrombosis will produce complete lumen occlusion.
 Recent epidemiological studies of human patients with myocardial infarction have demonstrated that in many cases a triggering activity, such as physical exertion, precipitates the acute onset of the disorder. Although a better understanding of plaque vulnerability and triggering would be of great value, knowledge of this process is limited because human studies are difficult and a suitable animal model has not been used.
In human patients, the opportunity to study factors responsible for acute onset of myocardial infarction is limited because coronary angiography performed before the event cannot prospectively identify plaques vulnerable to disruption.(9) After the event, angiography cannot distinguish the features of the plaque responsible for the disruption from those resulting from the disruption.(10) Although findings at autopsy provide detailed information about plaque disruption, these observations may be biased toward more advanced disease, since plaque disruptions producing total vascular occlusion and death may be more severe than those occurring in asymptomatic individuals or in patients with unstable angina or nonfatal myocardial infarction.
These difficulties, inherent in the study of plaque disruption and thrombosis in human patients, create a great need for an animal model of the process. More than 30 years ago, Constantinides and Chakravarti(13) developed such a model in atherosclerotic rabbits. Atherosclerotic plaques were produced in New Zealand White rabbits by intermittent cholesterol feeding. Triggering of plaque disruption and thrombosis was then accomplished by intraperitoneal injection of Russell’s viper venom (RVV, a procoagulant and endothelial toxin) followed by the intravenous injection of histamine, a vasopressor in rabbits. The aortas of the rabbits were then found to have disrupted atherosclerotic plaques with overlying platelet-rich thrombi.
Despite the similarity of these lesions to those observed in human patients, the model has received little attention or use during the past 3 decades. A recent review of the animal models of thrombosis currently in use noted that “thus far, it has not been possible to duplicate in a model the most common clinical cause of thrombosis—an ulcerated atherosclerotic plaque.”(14)
The advantage of the Constantinides model over other animal models used to study thrombosis is that it uses a biological intervention to trigger localized atherosclerotic plaque disruption and formation of platelet-rich arterial thrombi. The model facilitates the study of the process because the investigator determines when disruption and thrombosis will occur.
Disadvantages of the Constantinides model are
  • (1) the low yield of triggering (only about one third of the rabbits developed thrombosis) and
  • (2) the long (8-month) preparatory period. In addition, there is a need to replicate the findings of Constantinides and Chakravarti(13) from 30 years ago because of the biological variability of rabbit strains and RVV.
It cannot be assumed that the rabbits and RVV currently available will produce the results obtained in the 1960s.
In this study, we attempted to reproduce the original model of Constantinides.13 In addition, we wanted to determine whether mechanical injury to the aorta early in the preparatory phase could enhance the development of vulnerable plaques, thereby increasing the yield of disrupted plaques and shortening the preparatory period.

Methods

Fifty-three New Zealand White rabbits weighing between 2 and 3 kg were started on the experimental protocol; 41 survived until the time of attempted triggering. In these 41 rabbits, four dietary and interventional regimens were used in preparation for attempted triggering (Fig 1⇓). The control group, group I, consisted of normal rabbits (n=9) that were fed a regular diet for 8 months. Group II rabbits (n=13) were fed a high-cholesterol diet (1% cholesterol, ICN) for 2 months alternated with 2 months of a regular diet for a total of 8 months.15 Rabbits in group III (n=5) underwent balloon-induced arterial injury and were maintained on a regular diet for 8 months. Rabbits in group IV (n=14) underwent balloon-induced arterial injury, were maintained on a 1% cholesterol diet for 2 months, then were given a regular diet for 2 months for a total of 4 months.
Balloon-induced arterial wall injury of the aorta was performed with a 4F Fogarty catheter introduced through a femoral artery cutdown. The catheter was advanced in a retrograde fashion to the aortic valve and then withdrawn 3 cm. The balloon was inflated with 1.5 cm3 of air, and the catheter was retracted down to the iliofemoral artery. This was repeated three times in each rabbit as cm3 described previously.16 Rabbits were anesthetized with ketamine (50 mg/kg IM) and xylazine (20 mg/kg IM).

Of the 12 rabbits that died during the preparatory period, 5 were in group II, 2 in group III, and 5 in group IV. Seven of the 12 rabbits that died prematurely underwent an autopsy, and none had evidence of plaque disruption or arterial thrombosis. The causes of death included respiratory infection and liver failure from lipid infiltration.

The triggering agents RVV (Sigma Chemical Co) and histamine (Eli Lilly) were administered according to the method of Constantinides and Chakravarti.(13) RVV (0.15 mg/kg) was given by intraperitoneal injection 48 and 24 hours before the rabbits were killed. Thirty minutes after each RVV injection, histamine (0.02 mg/kg) was administered intravenously through an ear vein. Rabbits were killed by an overdose of intravenous pentobarbital and potassium chloride. The aorta and iliofemoral arteries were dissected and excised, and the intimal surface was exposed by an anterior longitudinal incision of the vessel.

The total surface area of the aorta, from the aortic arch to the distal common iliac branches, was measured. The surface area covered with atherosclerotic plaque and the surface area covered with antemortem thrombus were then determined. Images of the arterial surface were collected with a color charge-coupled device camera (TM 54, Pulnix) and digitized by an IBM PC/AT computer with a color image processing subsystem. The digitized images were calibrated by use of a graticule, and surface areas were measured by use of a customized quantitative image analysis package.

Tissue samples (1 cm in length) were taken from the thoracic aorta, 3 and 6 cm distal to the aortic valve; from the abdominal aorta, 7 and 4 cm proximal to the iliac bifurcation; and from the iliofemoral arteries. and prepared for and examined by light microscopy and they were examined by quantitative colorimetric assay.  Electron microscopy was also carried out with a Hitachi 600 microscope.

Biochemical analysis was done for tissue cholesterol. Free cholesterol and cholesteryl esters in the aorta were determined by high-performance liquid chromatography (HPLC) on the basis of the method of Kim and Chung. Each sample of aorta was ground to a fine powder with anhydrous sodium sulfate and extracted twice with 5 mL chloroform: methanol (2:1). The extract was dried under nitrogen and redissolved in 5 mL isopropanol.   Serum cholesterol, plasma fibrinogen, and platelet counts were done.

Overall comparison among the four groups was conducted with Fisher’s exact test and the Kruskal-Wallis test for discrete and continuous data, respectively. Comparisons between any two groups of rabbits were made by an exact Wilcoxon midrank test.23 P<.05 was considered statistically significant, and measured data were reported as mean±SD.

Results

Extent of Thrombosis After Triggering

In the 41 rabbits that underwent attempted triggering, the frequency of plaque disruption and focal thrombosis varied markedly depending on the type of preparatory regimen. In group I, only 1 of 9 control rabbits developed a thrombus. This was a small white thrombus with a surface area of 2 mm^2. Three of the 13 rabbits in group II on a 1% cholesterol diet developed white thrombi, all of which were small but were larger than that observed in group I (mean surface area, 15.3±19.2 mm^2). In group III, each of the 5 rabbits that had balloon-induced arterial wall injury developed large white thrombi (mean surface area, 223.0±119 mm^2). Ten of 14 group IV rabbits, with combined arterial wall injury and a high-cholesterol diet, developed white thrombi, all of which were large (mean surface area, 263.0±222 mm^2).

Both the frequency of occurrence and the amount of thrombus formation were significantly different among all four groups (P<.001 and P<.0001, respectively). However, the frequency and the amount of thrombus formation tested individually between groups I and II were not statistically different. The average surface area covered by thrombi in rabbits from groups III and IV was significantly greater than that observed in group II (P=.03 and P=.02) or group I (P=.001 and P=.001) rabbits. The average surface area covered by thrombi did not significantly differ between rabbits in group III versus those in group IV.

No white thrombi were noted in the ascending aorta or the aortic arch. In the non–balloon-treated rabbits in groups I and II, only 1 of 5 thrombi was in the abdominal aorta. In the balloon-injured rabbits in groups III and IV, the thrombi were almost evenly distributed between the thoracic and abdominal aorta (48 versus 66). There were more thrombi in the balloon-injured rabbits than in the non–balloon-injured rabbits (P<.002).

Extent of Plaque Covering the Arterial Surface

 The plaque surface area was significantly different among the four groups (P<.0001). Plaque was present in all the rabbits that were maintained on a high-cholesterol diet or that had balloon-induced arterial injury. The plaque distribution for each group is shown in Fig 4⇓. (not shown) Individual comparisons showed a larger amount of plaque in rabbits from groups III and IV than in those from group II (P=.04 and P=.001, respectively). There was no significant difference in the amount of the plaque in group III versus group IV rabbits. The Table demonstrates the relations of the various groups regarding frequency of disruption with the amount of thrombus formation and plaque surface area.
 The intima in group I rabbits appeared normal by gross inspection. In group II rabbits, white-yellow plaque was widely distributed over the arterial surface, with focal punctate ulceration occasionally noted under a dissecting microscope. In group III rabbits, the intima was smooth and widely covered with white plaque. Group IV rabbits had extensive sheets of elevated white-yellow plaque. By gross visualization, ulceration of the surface was present without superimposed thrombus in two rabbits in group IV.

Histological Features of Plaque Disruption and Thrombosis

 Over 4500 tissue sections were prepared and evaluated. Light microscopy of arterial samples from group I showed normal vascular histology. Group II samples had a predominance of foam cell infiltration of the intima surrounded with connective tissue. Group III samples had fibromuscular plaque composed mostly of muscular cell elements and minimal fibroconnective tissue. This was confirmed by Masson’s trichrome stains showing mostly red muscle cells and minimal blue fibrous tissue. Group IV samples had extensive plaque with an infiltration predominantly composed of foam cells.

Light microscopic examination of adjacent serial sections from thrombosis sites revealed platelet-rich thrombi with interrupted but long adhesion sites to the arterial wall over most of their length. Early organization and inflammatory cell infiltration were present within the thrombi. In sections from groups II and IV, some areas of plaque directly adjacent to the thrombi had marked thinning of the connective tissue cap and areas of dehiscent foam cells,. These observations were rare and were noted in <0.5% of the examined lesions. In most cases, the arterial thrombus was not located at a site of obvious plaque rupture. Foam cell infiltration was also noted adjacent to sites of thrombosis.

Figure 6.

A, Light micrograph shows that degenerated foam cells are present in a large cavity below a cap separating the cavity from the intimal surface of thoracic aorta from a rabbit in group IV (Movat’s pentachrome, magnification ×40). B, Light micrograph of large thrombus attached to the luminal surface of the thoracic aorta in the same rabbit shown in A. The cavitation is seen below the thrombus, and the intimal surface is markedly thinned (Masson’s trichrome, magnification ×16). C, Light micrograph of thrombus overlying a region of plaque with a large accumulation of foam cells from a rabbit in group IV. The free edges of the thrombus correspond to the underlying contour of the plaque, which suggests that the thrombus became detached during fixation (Masson’s trichrome, magnification ×25). D, Light micrograph of thrombus from the abdominal aorta in a rabbit from group IV, 48 hours after triggering. The thrombus is firmly attached and becoming organized. The yellow stain represents red blood cells, and the fibrin and platelets appear pink (Carstair’s stain, magnification ×25).
The degree of blue staining indicative of fibrous tissue in Masson’s trichrome–prepared slides was greatest in group II samples, as represented by values closer to the pure blue region (0.0) on CIE coordinates. Group II samples (0.33±0.046, mean±SD) were more blue than group III (0.43±0.06, P<.001) or group IV samples (0.38±0.05, P<.001). The degree of blue staining was not statistically different between samples from groups III and IV.
Scanning electron microscopy demonstrated fissures of various lengths below areas from which overlying thrombi were removed. Endothelial cells could be seen lining the intimal surface of the aorta in the rabbits that had undergone balloon-induced arterial wall injury 8 months earlier. Surface blebs and focal endothelial breakdown with ulcer formation, without grossly visible thrombosis, were occasionally seen in samples from groups II and IV. The base of these ulcers was layered with platelets, fibrin, and red blood cells. Transmission electron microscopy of areas with thrombosis confirms that the thrombi were platelet rich.

Biochemical Findings

 Baseline serum cholesterol for all rabbits was 50±25 mg/dL and did not differ among the four groups. In rabbits in groups II and IV, which received cholesterol feeding, serum cholesterol rose to an average peak level of 2500± 1200 mg/dL.
In the two groups that received cholesterol feeding, the total cholesterol content in tissue samples pooled from the thoracic and abdominal aorta was significantly higher in group IV (16±7.2 mg/g) than in group II (2.8±1.6 mg/g) (P<.0001). Rabbits that were maintained on a regular diet (groups I and III) had equally low levels of tissue cholesterol (0.05±0.04 versus 0.06±0.02 mg/g, P=NS).

Hematological Changes Accompanying Triggering

The average fibrinogen level before triggering in the 27 rabbits in which fibrinogen was measured was 210±119 mg/dL; it rose to 403±168 mg/dL 48 hours after triggering (P<.001). Plasma fibrinolytic activity did not change after triggering (85.5±37.8 versus 94.8±33.5 arbitrary units). Platelet counts (measured in only 19 rabbits in groups II and IV) decreased from 350±84×103 to 215±116×103 per cubic millimeter after triggering (P<.001). White blood cell count did not decrease after triggering (12.8±13.0 versus 12.8±7.1×103 cells per cubic millimeter). However, the hematocrit dropped from 35.7±3.8% to 32.0±5.8% (P<.0002).

Discussion

The results demonstrate that vulnerable plaques can be produced and that plaque disruption and platelet-rich arterial thrombus formation may be triggered pharmacologically in an animal model of arterial plaque. This finding documents that the New Zealand White rabbit strains and the RVV currently available can be used to obtain the same results observed by Constantinides and Chakravarti(13) more than 30 years ago.
The frequency of successful triggering was dependent on the type of preparatory regimen used. In control rabbits maintained on a regular diet, only 1 of 9 developed a small thrombus after injection of the triggering agents. Although rabbits fed a high-cholesterol diet had more thrombosis after triggering, the values were not statistically different between rabbits in groups I and II. In other studies of triggering of cholesterol-fed rabbits, a total of 7 of 30 rabbits have developed thrombi, but this also does not achieve statistical significance (unpublished data, 1994). The number of rabbits studied may have been too low to demonstrate a moderate difference of thrombus occurrence. However, earlier work by Constantinides and Chakravarti(13 24) demonstrated a frequency of thrombi in 1 of 22 rabbits not fed cholesterol versus 22 of 77 rabbits fed cholesterol, which does achieve statistical significance (P<.02). This indicates that a larger sample may demonstrate a difference between groups I and II and that cholesterol feeding increases the likelihood of the disruption and thrombosis process in the rabbit model. Thus, our results in conjunction with those of Constantinides and Chakravarti suggest that thrombosis triggered by RVV and histamine may be facilitated in the presence of atherosclerosis. However, these observations do not preclude the possibility of thrombosis in a normal artery, which can be induced by injury from various triggers.
Rabbits subjected to arterial balloon injury developed extensive thrombosis only after triggering, as did rabbits subjected to both arterial injury and a high-cholesterol diet. Thus, a high-cholesterol diet especially in the presence of mechanical injury is capable of producing a plaque vulnerable to disruption and thrombosis by triggering with RVV and histamine.

Production of Vulnerable Plaque by Cholesterol Feeding

The technique of pulsed cholesterol feeding used in this study has been shown to be an effective method of producing experimental atherosclerosis, as have continuous cholesterol feeding regimens. Recently, it has been demonstrated that cholesterol feeding induces an upregulation of vascular cell adhesion molecule-1 in rabbit endothelium. This may predispose a site to monocyte adhesion and migration into the subendothelial space. Continued macrophage accumulation may make the site particularly vulnerable to disruption and thrombosis.
Autopsy studies in humans have led to the hypothesis that a lesion with a lipid pool beneath a thin cap is particularly vulnerable to disruption and thrombosis.4 5 This morphology has been shown to generate stress concentrations that would predispose a plaque to disrupt.  Although sites with lipid pools and thin caps were noted in the present study, their occurrence was too limited to permit studies to determine whether these were sites particularly prone to thrombosis. Cholesterol feeding for 2 years may be required to produce a sufficient number of such lesions to determine their vulnerability to disruption.

Production of Vulnerable Plaque by Balloon-Induced Injury

An important finding of this study is that vulnerability to disruption and thrombosis was present 8 months after deendothelialization with balloon-induced arterial wall injury in rabbits on a regular diet (group III). This occurred in the presence of a regenerated endothelium overlying a diffuse fibromuscular plaque. Previous reports have demonstrated that endothelium that regenerates after balloon deendothelialization is physiologically dysfunctional for a prolonged period. From our study, it appears that endothelial function is compromised in its role as a thrombosis-resistant surface over a long period as well. An important factor that may contribute to the altered function is the presence of underlying plaque.

Triggering Agents RVV and Histamine

Among its numerous constituents, RVV contains proteases that activate factors V and X. Such activation leads to thrombosis, which is most likely to occur at sites of cell injury. In addition to this procoagulant effect, RVV is a direct endothelial toxin.31 However, in the absence of arterial abnormalities produced by cholesterol feeding or other means, RVV alone or in combination with a vasoconstrictor agent rarely produces thrombosis.4 The increase in fibrinogen levels and the stability of hematological factors during triggering indicate that RVV does not act by producing a disseminated coagulopathy. The localization of thrombus at focal arterial sites is further evidence that this model does not merely produce a nonspecific thrombotic effect.
Histamine is an arterial vasoconstrictor in rabbits. This effect is mediated by an H1 receptor that regulates release of norepinephrine at the presynaptic norepinephrine sites. Histamine may contribute to plaque disruption by raising the arterial pressure and stress on the plaque and/or by the development of vasospasm. Other, similar agents, thromboxane A2 and serotonin, also have been shown to result in severe vasoconstriction of epicardial coronary arteries that is mediated by platelet deposition at stenosed sites.

Comparison With Other Models

This is a unique model that combines features of several other animal models that have been used to study atherosclerosis and thrombosis. With regard to thrombosis, the model provides the opportunity to extend observations previously made in other animal models of thrombosis to the special conditions surrounding triggering of acute cardiovascular syndromes. While the model of Folts et al has been invaluable in assessing enhanced platelet deposition in dog and pig coronary arteries, it requires both endothelial injury and the production of a 60% to 70% lumen stenosis. Moreover, it does not use an atherosclerotic artery with a vulnerable plaque.
Badimon et al used a flow chamber to evaluate platelet deposition on activated arterial surfaces. They demonstrated that deep arterial injury results in more thrombus formation than superficial injury. However, their model does not recreate the in vivo environment or provide an opportunity for evaluation of various thrombogenic sites, as does the model presented in this study.

Relation of the Model to Human Coronary Thrombosis

Certain features of the lesions seen in this model are similar to those of human lesions seen at autopsy of patients with fatal myocardial infarction, ie, a lesion with a fissured collagen cap overlying a lipid mass of amorphous and crystalline lipid. However, most of the lesions in the model did not have these features and were more consistent with a recent pathological study of fatal coronary thrombosis, which revealed that in approximately half the cases, the plaque was relatively intact but an inflammatory infiltrate was present.36 Perhaps the incidence of plaque rupture causing thrombus may be even lower in patients with nonfatal coronary thrombosis, as suggested from angioscopic studies of coronary arteries that have shown plaque ulceration of various severities.
Although the model we used produced lesions with many similarities to the nonruptured lesions described in patients, extension of this preparation for a 2-year period has been documented to produce lesions with deep fissures similar to those observed in many patients with fatal coronary thrombosis. Also, use of balloon injury in this model to enhance plaque development resulted in plaques that were morphologically similar to advanced plaques induced by the alternating high-cholesterol diet.
Analyses of human plaques have demonstrated that disrupted plaques have significantly less collagen, glycosaminoglycans, and smooth muscle cells and more extracellular lipid and macrophages than do nondisrupted plaques. This is consistent with findings in our study that rabbits in group II had more connective tissue and a lower rate of disruption and thrombosis than those in groups III and IV.
Perhaps the major limitation of this study is that it used a complex pharmacological mixture as the trigger, which makes speculation on the mechanism of action difficult. Further studies will be necessary to determine which components of RVV and histamine are responsible for the focal thrombosis.

Potential Utility of the Model to Study Plaque Disruption and Thrombosis

The observation that large, platelet-rich thrombi can be obtained by triggering in animals with underlying plaques produced by cholesterol feeding or by balloon injury broadens the types of plaque that can be studied for vulnerability. Various types of preparatory regimens could be studied for their ability to promote or retard the development of vulnerable plaque.
The model also can be used to test pharmacological agents that may reduce the development of vulnerable atherosclerotic plaques, such as lipid-lowering agents, antioxidants, calcium channel blocking agents, and angiotensin-converting enzyme inhibitors. Antiplatelet and other antithrombotic drug therapies can be tested for the ability to reduce the amount of thrombus complicating plaque disruption. Finally, the model can be used to characterize the biochemical and cellular bases for plaque vulnerability by comparing the features of sites that do and do not develop thrombi soon after triggering.

 References

3 Friedman M, van den Bovenkamp GJ. The pathogenesis of a coronary thrombus. Am J Pathol. 1966;80:19-44.
4 Constantinides P. Plaque fissures in human coronary thrombosis. J Atheroscler Res. 1966;6:1-17.
5 Davies MJ, Thomas AC. Plaque fissuring: the cause of acute myocardial infarction causing sudden ischaemic death, and crescendo angina. Br Heart J. 1985;53:363-373. FREE Full Text
8 Tofler GH, Stone PH, Maclure M, Edelman E, Davis VG, Robertson T, Antman EM, Muller JE, and the MILIS Study Group. Analysis of possible triggers of acute myocardial infarction (the MILIS Study). Am J Cardiol. 1990;66:22-27. CrossRefMedline
9  Little WC, Constantinescu M, Applegate RJ, Kutcher MA, Burrows MT, Kahl FR, Santamore WP. Can coronary angiography predict the site of a subsequent myocardial infarction in patients with mild-to-moderate coronary artery disease? Circulation. 1988;78:1157-1166. Abstract/FREE Full Text
10 Ambrose JA, Winters SL, Arora RR, Eng A, Riccio A, Gorlin R, Fuster V. Angiographic evolution of coronary artery morphology in unstable angina. J Am Coll Cardiol. 1986;7:472-478. Abstract
11 Davies MJ, Bland MJ, Hartgartner WR, Angelini A, Thomas AC. Factors influencing the presence or absence of acute coronary thrombi in sudden ischemic death. Eur Heart J. 1989;10:203-208. Abstract/FREE Full Text
12  JH, Fuster V, Badimon L, Taubman M, Badimon J, Cheseboro JH. Syndromes of accelerated atherosclerosis: role of vascular injury and smooth muscle cell proliferation. J Am Coll Cardiol. 1990;15:1667-1687. Abstract
13 Constantinides P, Chakravarti RN. Rabbit arterial thrombosis production by systemic procedures. Arch Pathol. 1961;72:197-208. Medline
14  Runge RS, Haber E. Animal models for the study of thrombolysis in vivo. Circulation. 1991;83(suppl IV): IV-1-IV-2. Abstract.
15 Constantinides P, Booth J, Carlson G. Production of advanced cholesterol atherosclerosis in the rabbit. Arch Pathol. 1960;70:80-92.

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Curator: Aviva Lev-Ari, PhD, RN

Evidence of HDL Modulation of eNOS in Humans

 Whereas the functional link between HDL and eNOS has been appreciated only recently, the relationship between HDL and endothelium-dependent vasodilation has been known for some time. In studies of coronary vasomotor responses to acetylcholine, it was noted in 1994 that patients with elevated HDL have greater vasodilator and attenuated vasoconstrictor responses (Zeiher et al., 1994).

Circulation, 89:2525–2532.

Studies of flow-mediated vasodilation of the brachial artery have also shown that HDL cholesterol is an independent predictor of endothelial function (Li et al., 2000).

Int. J. Cardiol., 73:231–236

Induction of NO Production and Stimulation of eNOS

Mechanism of Action (MOA) for Nitric Oxide (NO) and endothelial Nitric Oxide Syntase (eNOS) are described in George T. and P. Ramwell, (2004). Nitric Oxide, Donors, & Inhibitors. Chapter 19 in Katzung, BG., Basic & Clinical Pharmacology. McGraw-Hill, 9th Edition, pp. 313 – 318

http://books.google.com/books/about/Basic_and_Clinical_Pharmacology.html?id=4O7ghcthkt4C

The direct, short-term impact of HDL on endothelial function also has recently been investigated in humans. One particularly elegant study recently evaluated forearm blood flow responses in individuals who are heterozygous for a loss-of-function mutation in the ATP-binding cassette transporter 1 (ABCA1) gene. Compared with controls, ABCA1 heterozygotes (six men and three women) had HDL levels that were decreased by 60%, their blood flow responses to endothelium-dependent vasodilators were blunted, and endothelium-independent responses were unaltered. After a 4-hour infusion of apoAI/phosphatidylcholine disks, their HDL level increased threefold and endothelium-dependent vasomotor responses were fully restored (Bisoendial et al., 2003). It has also been observed that endothelial function is normalized in hypercholesterolemic men with normal HDL levels shortly following the administration of apoAI/phosphatidylcholine particles (Spieker et al., 2002).

Circulation, 105:1399–1402.

Thus, evidence is now accumulating that HDL is a robust positive modulator of endothelial NO production in humans (Shaul & Mineo, 2004).

J Clin Invest., 15; 113(4): 509–513.

HDL is more than an eNOS Agonist

 In addition to the modulation of NO production by signaling events that rapidly dictate the level of enzymatic activity, important control of eNOS involves changes in the abundance of the enzyme. In a clinical trial by the Karas laboratory of niacin therapy in patients with low HDL levels (nine males and two females), flow-mediated dilation of the brachial artery was improved in association with a rise in HDL of 33% over 3 months (Kuvin et al., 2002).

Am. Heart J., 144:165–172.

They also demonstrated that eNOS expression in cultured human endothelial cells is increased by HDL exposure for 24 hours. They further showed that the increase in eNOS is related to an increase in the half-life of the protein, and that this is mediated by PI3K–Akt kinase and MAPK (Ramet et al., 2003).

J. Am. Coll. Cardiol., 41:2288–2297.

Thus, the same mechanisms that underlie the acute activation of eNOS by HDL appear to be operative in upregulating the expression of the enzyme.

The current understanding of the mechanism by which HDL enhances endothelial NO production is summarized in Shaul & Mineo (2004), Figure 1.

J Clin Invest., 15; 113(4): 509–513.

It describes the mechanism of action for HDL enhancement of NO production by eNOS in vascular endothelium.

(a)   HDL causes membrane-initiated signaling, which stimulates eNOS activity. The eNOS protein is localized in cholesterol-enriched (orange circles) plasma membrane caveolae as a result of the myristoylation and palmitoylation of the protein. Binding of HDL to SR-BI via apoAI causes rapid activation of the nonreceptor tyrosine kinase src, leading to PI3K activation and downstream activation of Akt kinase and MAPK. Akt enhances eNOS activity by phosphorylation, and independent MAPK-mediated processes are additionally required (Duarte, et al., 1997). .Eur J Pharmacol, 338:25–33. HDL also causes an increase in intracellular Ca2+ concentration (intracellular Ca2+ store shown in blue; Ca2+ channel shown in pink), which enhances binding of calmodulin (CM) to eNOS. HDL-induced signaling is mediated at least partially by the HDL-associated lysophospholipids SPC, S1P, and LSF acting through the G protein–coupled lysophospholipid receptor S1P3. HDL-associated estradiol (E2) may also activate signaling by binding to plasma membrane–associated estrogen receptors (ERs), which are also G protein coupled. It remains to be determined if signaling events are also directly mediated by SR-BI (Yuhanna et al., 2001), (Nofer et al., 2004), (Gong et al., 2003), (Mineo et al., 2003).

Nat. Med.7:853–857.

J. Clin. Invest.,113:569–581.

J. Clin. Invest., 111:1579–1587.

J. Biol. Chem., 278:9142–9149.

(b)   HDL regulates eNOS abundance and subcellular distribution. In addition to modulating the acute response, the activation of the PI3K–Akt kinase pathway and MAPK by HDL upregulates eNOS expression (open arrows). HDL also regulates the lipid environment in caveolae (dashed arrows). Oxidized LDL (OxLDL) can serve as a cholesterol acceptor (orange circles), thereby disrupting caveolae and eNOS function. However, in the presence of OxLDL, HDL maintains the total cholesterol content of caveolae by the provision of cholesterol ester (blue circles), resulting in preservation of the eNOS signaling module (Ramet et al., 2003), (Blair et al., 1999), (Uittenbogaard et al., 2000).

J. Am. Coll. Cardiol., 41:2288–2297.

J. Biol. Chem., 274:32512–32519.

J. Biol. Chem., 275:11278–11283.

Source for HDL-eNOS Figure: Shaul & Mineo (2004).

 

HDL enhances NO production by eNOS in vascular endothelium.

FIGURE SOURCE:

Shaul, PW and Mineo, C, (2004). HDL action on the vascular wall: is the answer NO? J Clin Invest., 15; 113(4): 509–513.

eNOS is not Activated by Nebivolol in Human Failing Myocardium.

Nebivolol is a highly selective beta(1)-adrenoceptor blocker with additional vasodilatory properties, which may be due to an endothelial-dependent beta(3)-adrenergic activation of the endothelial nitric oxide synthase (eNOS). beta(3)-adrenergic eNOS activation has been described in human myocardium and is increased in human heart failure. Therefore, this study investigated whether nebivolol may induce an eNOS activation in cardiac tissue. Immunohistochemical stainings were performed using specific antibodies against eNOS translocation and eNOS serine(1177) phosphorylation in rat isolated cardiomyocytes, human right atrial tissue (coronary bypass-operation), left ventricular non-failing (donor hearts) and failing myocardium after application of the beta-adrenoceptor blockers nebivolol, metoprolol and carvedilol, as well as after application of BRL 37344, a specific beta(3)-adrenoceptor agonist. BRL 37344 (10 muM) significantly increased eNOS activity in all investigated tissues (either via translocation or phosphorylation or both). None of the beta-blockers (each 10 muM), including nebivolol, increased either translocation or phosphorylation in any of the investigated tissues. In human failing myocardium, nebivolol (10 muM) decreased eNOS activity. In conclusion, nebivolol shows a tissue-specific eNOS activation. Nebivolol does not activate the endothelial eNOS in end-stage human heart failure and may thus reduce inhibitory effects of NO on myocardial contractility and on oxidative stress formation. This mode of action may be of advantage when treating heart failure patients.

Brixius K, Song Q, Malick A, Boelck B, Addicks K, Bloch W, Mehlhorn U, Schwinger R, (2006). eNOS is not activated by nebivolol in human failing myocardium.

Life Sci. 2006 Apr 25

REFERENCES

Brixius K, Song Q, Malick A, Boelck B, Addicks K, Bloch W, Mehlhorn U, Schwinger R, (2006). eNOS is not activated by nebivolol in human failing myocardium.

Life Sci. 2006 Apr 25

Mineo C, Yuhanna IS, Quon MJ, Shaul PW., (2003). HDL-induced eNOS activation is mediated by Akt and MAP kinases. J. Biol. Chem., 278:9142–9149.

Shaul, PW and Mineo, C, (2004). HDL action on the vascular wall: is the answer NO? J Clin Invest., 15; 113(4): 509–513.

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