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Archive for the ‘Neuroscience’ Category


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

 

The relationship between gut microbial metabolism and mental health is one of the most intriguing and controversial topics in microbiome research. Bidirectional microbiota–gut–brain communication has mostly been explored in animal models, with human research lagging behind. Large-scale metagenomics studies could facilitate the translational process, but their interpretation is hampered by a lack of dedicated reference databases and tools to study the microbial neuroactive potential.

 

Out of all the many ways, the teeming ecosystem of microbes in a person’s gut and other tissues might affect health. But, its potential influences on the brain may be the most provocative for research. Several studies in mice had indicated that gut microbes can affect behavior, and small scale studies on human beings suggested this microbial repertoire is altered in depression. Studies by two large European groups have found that several species of gut bacteria are missing in people with depression. The researchers can’t say whether the absence is a cause or an effect of the illness, but they showed that many gut bacteria could make substances that affect the nerve cell function—and maybe the mood.

 

Butyrate-producing Faecalibacterium and Coprococcus bacteria were consistently associated with higher quality of life indicators. Together with DialisterCoprococcus spp. was also depleted in depression, even after correcting for the confounding effects of antidepressants. Two kinds of microbes, Coprococcus and Dialister, were missing from the microbiomes of the depressed subjects, but not from those with a high quality of life. The researchers also found the depressed people had an increase in bacteria implicated in Crohn disease, suggesting inflammation may be at fault.

 

Looking for something that could link microbes to mood, researchers compiled a list of 56 substances important for proper functioning of nervous system that gut microbes either produce or break down. They found, for example, that Coprococcus seems to have a pathway related to dopamine, a key brain signal involved in depression, although they have no evidence how this might protect against depression. The same microbe also makes an anti-inflammatory substance called butyrate, and increased inflammation is implicated in depression.

 

Still, it is very much unclear that how microbial compounds made in the gut might influence the brain. One possible channel is the vagus nerve, which links the gut and brain. Resolving the microbiome-brain connection might lead to novel therapies. Some physicians and companies are already exploring typical probiotics, oral bacterial supplements, for depression, although they don’t normally include the missing gut microbes identified in the new study.

 

References:

 

https://www.sciencemag.org/news/2019/02/evidence-mounts-gut-bacteria-can-influence-mood-prevent-depression?utm_source=Nature+Briefing

 

https://www.nature.com/articles/s41564-018-0337-x

 

https://www.ncbi.nlm.nih.gov/pubmed/22968153

 

https://www.ncbi.nlm.nih.gov/pubmed/24888394

 

https://www.ncbi.nlm.nih.gov/pubmed/27067014

 

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  1. Lungs can supply blood stem cells and also produce platelets: Lungs, known primarily for breathing, play a previously unrecognized role in blood production, with more than half of the platelets in a mouse’s circulation produced there. Furthermore, a previously unknown pool of blood stem cells has been identified that is capable of restoring blood production when bone marrow stem cells are depleted.

 

  1. A new drug for multiple sclerosis: A new multiple sclerosis (MS) drug, which grew out of the work of UCSF (University of California, San Francisco) neurologist was approved by the FDA. Ocrelizumab, the first drug to reflect current scientific understanding of MS, was approved to treat both relapsing-remitting MS and primary progressive MS.

 

  1. Marijuana legalized – research needed on therapeutic possibilities and negative effects: Recreational marijuana will be legal in California starting in January, and that has brought a renewed urgency to seek out more information on the drug’s health effects, both positive and negative. UCSF scientists recognize marijuana’s contradictory status: the drug has proven therapeutic uses, but it can also lead to tremendous public health problems.

 

  1. Source of autism discovered: In a finding that could help unlock the fundamental mysteries about how events early in brain development lead to autism, researchers traced how distinct sets of genetic defects in a single neuronal protein can lead to either epilepsy in infancy or to autism spectrum disorders in predictable ways.

 

  1. Protein found in diet responsible for inflammation in brain: Ketogenic diets, characterized by extreme low-carbohydrate, high-fat regimens are known to benefit people with epilepsy and other neurological illnesses by lowering inflammation in the brain. UCSF researchers discovered the previously undiscovered mechanism by which a low-carbohydrate diet reduces inflammation in the brain. Importantly, the team identified a pivotal protein that links the diet to inflammatory genes, which, if blocked, could mirror the anti-inflammatory effects of ketogenic diets.

 

  1. Learning and memory failure due to brain injury is now restorable by drug: In a finding that holds promise for treating people with traumatic brain injury, an experimental drug, ISRIB (integrated stress response inhibitor), completely reversed severe learning and memory impairments caused by traumatic brain injury in mice. The groundbreaking finding revealed that the drug fully restored the ability to learn and remember in the brain-injured mice even when the animals were initially treated as long as a month after injury.

 

  1. Regulatory T cells induce stem cells for promoting hair growth: In a finding that could impact baldness, researchers found that regulatory T cells, a type of immune cell generally associated with controlling inflammation, directly trigger stem cells in the skin to promote healthy hair growth. An experiment with mice revealed that without these immune cells as partners, stem cells cannot regenerate hair follicles, leading to baldness.

 

  1. More intake of good fat is also bad: Liberal consumption of good fat (monounsaturated fat) – found in olive oil and avocados – may lead to fatty liver disease, a risk factor for metabolic disorders like type 2 diabetes and hypertension. Eating the fat in combination with high starch content was found to cause the most severe fatty liver disease in mice.

 

  1. Chemical toxicity in almost every daily use products: Unregulated chemicals are increasingly prevalent in products people use every day, and that rise matches a concurrent rise in health conditions like cancers and childhood diseases, Thus, researcher in UCSF is working to understand the environment’s role – including exposure to chemicals – in health conditions.

 

  1. Cytomegalovirus found as common factor for diabetes and heart disease in young women: Cytomegalovirus is associated with risk factors for type 2 diabetes and heart disease in women younger than 50. Women of normal weight who were infected with the typically asymptomatic cytomegalovirus, or CMV, were more likely to have metabolic syndrome. Surprisingly, the reverse was found in those with extreme obesity.

 

References:

 

https://www.ucsf.edu/news/2017/12/409241/most-popular-science-stories-2017

 

https://www.ucsf.edu/news/2017/03/406111/surprising-new-role-lungs-making-blood

 

https://www.ucsf.edu/news/2017/03/406296/new-multiple-sclerosis-drug-ocrelizumab-could-halt-disease

 

https://www.ucsf.edu/news/2017/06/407351/dazed-and-confused-marijuana-legalization-raises-need-more-research

 

https://www.ucsf.edu/news/2017/01/405631/autism-researchers-discover-genetic-rosetta-stone

 

https://www.ucsf.edu/news/2017/09/408366/how-ketogenic-diets-curb-inflammation-brain

 

https://www.ucsf.edu/news/2017/07/407656/drug-reverses-memory-failure-caused-traumatic-brain-injury

 

https://www.ucsf.edu/news/2017/05/407121/new-hair-growth-mechanism-discovered

 

https://www.ucsf.edu/news/2017/06/407536/go-easy-avocado-toast-good-fat-can-still-be-bad-you-research-shows

 

https://www.ucsf.edu/news/2017/06/407416/toxic-exposure-chemicals-are-our-water-food-air-and-furniture

 

https://www.ucsf.edu/news/2017/02/405871/common-virus-tied-diabetes-heart-disease-women-under-50

 

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Memory Gene Goes Viral

Reporter: Irina Robu, PhD

A gene crucial for learning, called Arc can send genetic material from one neuron to another by using viruses was discovered by two independent team of scientist from University of Massachusetts Medical School and University of Utah which was published in Cell.  According to Dr. Edmund Talley, a program director at National Institute of Neurological Disorders and Stroke “this work is a great example of the importance of basic neuroscience research”.

Arc plays an important role in the brain’s ability to store new information, however little is known of how it works. According to the University of Utah scientists, research into the examination of the Arc gene began by introducing it into bacterial cells. When the cells made the Arc protein, it clumped together into a form that resembled a viral capsid, the shell that contains a virus’ genetic information. The Arc “capsids” appeared to mirror viral capsids in their physical structure in addition as their behavior and other properties.

At the same time, University of Massachusetts scientist led by Vivian Budnik, Ph. D and Travis Thomson, Ph.D. set out to scrutinize the contents of tiny sacks released by cells called extracellular vesicles. Their experiments in fruit flies revealed that motor neurons that control the flies’ muscles release vesicles containing a high concentration of the Arcgene’s messenger RNA (mRNA), the DNA-like intermediary molecule cells use to create the protein encoded by a DNA sequence.

Both groups similarly found evidence that Arc capsids contain Arc mRNA and that the capsids are released from neurons inside those vesicles. Also, both groups suggest that Arc capsids act like viruses by delivering mRNA to nearby cells. Furthermore, Dr. Shepherd’s team presented that the more active neurons are, the more of those vesicles they release. Dr. Shepherd’s group grew mouse neurons lacking the Arc gene in petri dishes filled with Arc-containing vesicles or Arc capsids alone. They revealed that the formerly Arc-less neurons took in the vesicles and capsids and used the Arc mRNA contained within to produce the Arc protein themselves. Finally, just like neurons that naturally manufacture the Arc protein, those cells made more of it when their electrical activity increased.

Both groups of scientists plan to examine why cells use this virus-like strategy to shuttle Arc mRNA between cells and which might allow the toxic proteins responsible for Alzheimer’s disease to spread through the brain.

SOURCE

http://www.sciencenewsline.com/news/2018011717480045.html

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Targeting amyloidopathy

Larry H. Bernstein, MD, FCAP

LPBI

 

Targeting a rare amyloidotic disease through rationally designed polymer conjugates

Inmaculada Conejos–Sánchez, Isabel Cardoso, Maria J. Saraiva, María J.Vicent
Journal of Controlled Release 178 (2014), 95–100
Saraiva et al. discovered in 2006 a RAGE-based peptide sequence capable of preventing transthyretin (TTR) aggregate-induced cytotoxicity, hallmark of initial stages of an inherited rare amyloidosis known as Familial Amyloidotic Polyneuropathy (FAP). To allow clinical progression of this peptidic sequence as FAP treatment, a family of polymer conjugates has been designed, synthesised and fully characterised. This approach fulfills the strategies defined in the Polymer Therapeutics area as an exhaustive physico-chemical characterisation fitting activity output towards a novel molecular target that is described here. RAGE peptide acts extracellularly, therefore, nointracellular drug delivery was necessary. PEG was selected as carrier and polymer–drug linker optimisation was then carried out by means of biodegradable (disulphide) and non-biodegradable (amide) covalent bonds. Conjugate size in solution, stability under invitro and in vivo scenarios and TTR binding affinity through surface plasmon resonance (SPR) was also performed with all synthesised conjugates. In their in vitro evaluation by monitoring the activation of caspase-3 in Schwann cells, peptide derivatives demonstrated retention of peptide activity reducing TTR aggregates (TTRagg) cytotoxicity upon conjugation and a greater plasma stability than the parent free peptide. The results also confirmed that a more stable polymer–peptide linker (amide) is required to secure therapeutic efficiency.

Polymer therapeutics are well established as successful first generation nanomedicines for treatment of infectious diseases and cancer[1]. Polymer–protein, drug and aptamer conjugates are innovative chemical entities capable of improving bioactive compound properties and thus increasing efficacy and decreasing toxicity[2,3]. Design of second generation of conjugates is now focussing on improved polymer structures, polymer–based combination therapy and novel molecular targets with great potential to further progress the clinical importance of these unique technologies [4]. Novel conjugates for the treatment of neuropathological disorders are proposed in this study. Amyloidosis is well known in the form of Alzheimer’s and Parkinson’s disease, but the target disease here is a rarer pathological disorder named familial amyloid polyneuropathy (FAP). FAPs constitute an important group of inherited amyloidosis diseases, and one of the most commonFAPs is caused by a mutated protein called transthyretin (TTR), which forms amyloid deposits, mainly in the peripheral nervous system [5]. The aggregation cascade of this mutated protein, produces a TTR aggregate (TTRagg) able to trigger neurodegeneration through engagement with the receptor-for-advanced-glycation-end-products (RAGE) which is present on peripheral neurons. RAGE signalling has been defined to be involved in many human pathologies such as Alzhehimer’s disease, diabetes and ageing, among others. This receptor is also up-regulated in tissues fromFAP patients [6]. The secreted RAGE form, named soluble RAGE (sRAGE), acts as a decoy to trap ligands and prevent interaction with cell surface receptors. sRAGE was shown to have important inhibitory effects in several cell cultures and transgenic mouse models, in which it prevented or reversed full-length RAGE signalling.

Saraiva et al. [7] discovered a specific peptidic sequence (named RAGE peptide) that is able to suppress TTRagg-induced cytotoxicity in cell culture. A reduced version of that peptide was proved to maintain the activity and the affinity of the initial peptide. The final peptide (compound A) contains 6 amino acids and responds to the sequence (from N to C terminus): YVRVRY. Although this provides an opportunity to design novel therapeutics for FAP treatment, peptide therapeutics themselves display well known challenges for in vivo use, e.g. low stability, poor pharmacokinetics and potential immunogenicity. Moreover the RAGE peptide demonstrates low solubility in plasma limiting its potential for i.v.administration.

……

Herein, novel specific nanoconjugates for the treatment of amyloidosis, and in particular familial amyloidotic polyneuropathy are reported. Apart from the research reported by Prof Arima et al. [22] using a hepatocyte-targeted FAP siRNA complex with lactosylated dendrimer (G3)/α-cyclodextrin(Lac-α-CDE(G3)), no other type of polymer therapeutic has been reported up to now for the treatment of this chronic degenerative family of diseases. Our rational design started from an active biomolecule of peptidic nature (RAGE peptide) that recognises the TTR prefibrillar aggregates responsible to promote cell death in FAPpatients [7]. The clinical progress of this promising inhibitor was masked by the well-known limitations of peptides, such as low solubility, low stability and possible immunogenicity. PEGylation through various linking strategies was successfully accomplished here as a solution for the named drawbacks, using a systematic approach to maintain peptide activity and receptor binding specificity. The data relating toTTR binding affinity, conjugate linker stability and the conjugate size distribution in solution of PEG– RAGE peptide conjugates indicate that the conjugates containing amide linkers have the greatest potential for further development as FAP inhibitors. Moreover, this novel conjugate has promising possibilities as a FAP therapeutic to be used alone in the early stages of the disease or as part of rationally designed combination therapy [23,24]. Preliminary in vivo studies (biodistribution) are shown in the supporting information demonstrating the enhanced plasma stability of the peptide upon conjugation (Fig.5S) , showing nospecific accumulation in any organ and renal excretion. More exhaustive in vivo experiments are currently ongoing with selected conjugates.

 

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Familial transthyretin amyloid polyneuropathy

Curator: Larry H. Bernstein, MD, FCAP

LPBI

 

First-Ever Evidence that Patisiran Reduces Pathogenic, Misfolded TTR Monomers and Oligomers in FAP Patients

We reported data from our ongoing Phase 2 open-label extension (OLE) study of patisiran, an investigational RNAi therapeutic targeting transthyretin (TTR) for the treatment of TTR-mediated amyloidosis (ATTR amyloidosis) patients with familial amyloidotic polyneuropathy (FAP). Alnylam scientists and collaborators from The Scripps Research Institute and Misfolding Diagnostics, Inc. were able to measure the effects of patisiran on pathogenic, misfolded TTR monomers and oligomers in FAP patients. Results showed a rapid and sustained reduction in serum non-native conformations of TTR (NNTTR) of approximately 90%. Since NNTTR is pathogenic in ATTR amyloidosis and the level of NNTTR reduction correlated with total TTR knockdown, these results provide direct mechanistic evidence supporting the therapeutic hypothesis that TTR knockdown has the potential to result in clinical benefit. Furthermore, complete 12-month data from all 27 patients that enrolled in the patisiran Phase 2 OLE study showed sustained mean maximum reductions in total serum TTR of 91% for over 18 months and a mean 3.1-point decrease in mNIS+7 at 12 months, which compares favorably to an estimated increase in mNIS+7 of 13 to 18 points at 12 months based upon analysis of historical data sets in untreated FAP patients with similar baseline characteristics. Importantly, patisiran administration continues to be generally well tolerated out to 21 months of treatment.

Read our press release

View the non-native TTR poster (480 KB PDF)

View the complete 12-month patisiran Phase 2 OLE data presentation (620 KB PDF)

We are encouraged by these new data that provide continued support for our hypothesis that patisiran has the potential to halt neuropathy progression in patients with FAP. If these results are replicated in a randomized, double-blind, placebo-controlled study, we believe that patisiran could emerge as an important treatment option for patients suffering from this debilitating, progressive and life-threatening disease.

 

Hereditary ATTR Amyloidosis with Polyneuropathy (hATTR-PN)

ATTR amyloidosis is a progressive, life-threatening disease caused by misfolded transthyretin (TTR) proteins that accumulate as amyloid fibrils in multiple organs, but primarily in the peripheral nerves and heart. ATTR amyloidosis can lead to significant morbidity, disability, and mortality. The TTR protein is produced primarily in the liver and is normally a carrier for retinol binding protein – one of the vehicles used to transport vitamin A around the body.  Mutations in the TTR gene cause misfolding of the protein and the formation of amyloid fibrils that typically contain both mutant and wild-type TTR that deposit in tissues such as the peripheral nerves and heart, resulting in intractable peripheral sensory neuropathy, autonomic neuropathy, and/or cardiomyopathy.

Click to Enlarge

 

ATTR represents a major unmet medical need with significant morbidity and mortality. There are over 100 reported TTR mutations; the particular TTR mutation and the site of amyloid deposition determine the clinical manifestations of the disease whether it is predominantly symptoms of neuropathy or cardiomyopathy.

Specifically, hereditary ATTR amyloidosis with polyneuropathy (hATTR-PN), also known as familial amyloidotic polyneuropathy (FAP), is an inherited, progressive disease leading to death within 5 to 15 years. It is due to a mutation in the transthyretin (TTR) gene, which causes misfolded TTR proteins to accumulate as amyloid fibrils predominantly in peripheral nerves and other organs. hATTR-PN can cause sensory, motor, and autonomic dysfunction, resulting in significant disability and death.

It is estimated that hATTR-PN, also known as FAP, affects approximately 10,000 people worldwide.  Patients have a life expectancy of 5 to 15 years from symptom onset, and the only treatment options for early stage disease are liver transplantation and TTR stabilizers such as tafamidis (approved in Europe) and diflunisal.  Unfortunately liver transplantation has limitations, including limited organ availability as well as substantial morbidity and mortality. Furthermore, transplantation eliminates the production of mutant TTR but does not affect wild-type TTR, which can further deposit after transplantation, leading to cardiomyopathy and worsening of neuropathy. There is a significant need for novel therapeutics to treat patients who have inherited mutations in the TTR gene.

Our ATTR program is the lead effort in our Genetic Medicine Strategic Therapeutic Area (STAr) product development and commercialization strategy, which is focused on advancing innovative RNAi therapeutics toward genetically defined targets for the treatment of rare diseases with high unmet medical need.  We are developing patisiran (ALN-TTR02), an intravenously administered RNAi therapeutic, to treat the hATTR-PN form of the disease.

Patisiran for the Treatment hATTR-PN

APOLLO Phase 3 Trial

In 2012, Alnylam entered into an exclusive alliance with Genzyme, a Sanofi company, to develop and commercialize RNAi therapeutics, including patisiran and revusiran, for the treatment of ATTR amyloidosis in Japan and the broader Asian-Pacific region. In early 2014, this relationship was extended as a significantly broader alliance to advance RNAi therapeutics as genetic medicines. Under this new agreement, Alnylam will lead development and commercialization of patisiran in North America and Europe while Genzyme will develop and commercialize the product in the rest of world.

 

Hereditary ATTR Amyloidosis with Cardiomyopathy (hATTR-CM)

ATTR amyloidosis is a progressive, life-threatening disease caused by misfolded transthyretin (TTR) proteins that accumulate as amyloid fibrils in multiple organs, but primarily in the peripheral nerves and heart. ATTR amyloidosis can lead to significant morbidity, disability, and mortality. The TTR protein is produced primarily in the liver and is normally a carrier for retinol binding protein – one of the vehicles used to transport vitamin A around the body.  Mutations in the TTR gene cause misfolding of the protein and the formation of amyloid fibrils that typically contain both mutant and wild-type TTR that deposit in tissues such as the peripheral nerves and heart, resulting in intractable peripheral sensory neuropathy, autonomic neuropathy, and/or cardiomyopathy.

Click to Enlarge                            http://www.alnylam.com/web/assets/tetramer.jpg

ATTR represents a major unmet medical need with significant morbidity and mortality. There are over 100 reported TTR mutations; the particular TTR mutation and the site of amyloid deposition determine the clinical manifestations of the disease, whether it is predominantly symptoms of neuropathy or cardiomyopathy.

Specifically, hereditary ATTR amyloidosis with cardiomyopathy (hATTR-CM), also known as familial amyloidotic cardiomyopathy (FAC), is an inherited, progressive disease leading to death within 2 to 5 years. It is due to a mutation in the transthyretin (TTR) gene, which causes misfolded TTR proteins to accumulate as amyloid fibrils primarily in the heart. Hereditary ATTR amyloidosis with cardiomyopathy can result in heart failure and death.

While the exact numbers are not known, it is estimated hATTR-CM, also known as FAC affects at least 40,000 people worldwide.  hATTR-CM is fatal within 2 to 5 years of diagnosis and treatment is currently limited to supportive care.  Wild-type ATTR amyloidosis (wtATTR amyloidosis), also known as senile systemic amyloidosis, is a nonhereditary, progressive disease leading to death within 2 to 5 years. It is caused by misfolded transthyretin (TTR) proteins that accumulate as amyloid fibrils in the heart. Wild-type ATTR amyloidosis can cause cardiomyopathy and result in heart failure and death. There are no approved therapies for the treatment of hATTR-CM or SSA; hence there is a significant unmet need for novel therapeutics to treat these patients.

Our ATTR program is the lead effort in our Genetic Medicine Strategic Therapeutic Area (STAr) product development and commercialization strategy, which is focused on advancing innovative RNAi therapeutics toward genetically defined targets for the treatment of rare diseases with high unmet medical need.  We are developing revusiran (ALN-TTRsc), a subcutaneously administered RNAi therapeutic for the treatment of hATTR-CM.

Revusiran for the Treatment of hATTR-CM

ENDEAVOUR Phase 3 Trial

In 2012, Alnylam entered into an exclusive alliance with Genzyme, a Sanofi company, to develop and commercialize RNAi therapeutics, including patisiran and revusiran, for the treatment of ATTR amyloidosis in Japan and the broader Asian-Pacific region. In early 2014, this relationship was extended as a broader alliance to advance RNAi therapeutics as genetic medicines. Under this new agreement, Alnylam and Genzyme have agreed to co-develop and co-commercialize revusiran in North America and Europe, with Genzyme developing and commercializing the product in the rest of world. This broadened relationship on revusiran is aimed at expanding and accelerating the product’s global value.

Pre-Clinical Data and Advancement of ALN-TTRsc02 for Transthyretin-Mediated Amyloidosis

We presented pre-clinical data with ALN-TTRsc02, an investigational RNAi therapeutic targeting transthyretin (TTR) for the treatment of TTR-mediated amyloidosis (ATTR amyloidosis).  In pre-clinical studies, including those in non-human primates (NHPs), ALN-TTRsc02 achieved potent and highly durable knockdown of serum TTR of up to 99% with multi-month durability achieved after just a single dose, supportive of a potentially once quarterly dose regimen. Results from studies comparing TTR knockdown activity of ALN-TTRsc02 to that of revusiran showed that ALN-TTRsc02 has a markedly superior TTR knockdown profile.  Further, in initial rat toxicology studies, ALN-TTRsc02 was found to be generally well tolerated with no significant adverse events at doses as high as 100 mg/kg.

Read our press release

View the presentation

http://www.alnylam.com/product-pipeline/hereditary-attr-amyloidosis-with-cardiomyopathy/

 

Emerging Therapies for Transthyretin Cardiac Amyloidosis Could Herald a New Era for the Treatment of HFPEF

Oct 14, 2015   |  Adam Castano, MDDavid Narotsky, MDMathew S. Maurer, MD, FACC

http://www.acc.org/latest-in-cardiology/articles/2015/10/13/08/35/emerging-therapies-for-transthyretin-cardiac-amyloidosis#sthash.9xzc0rIe.dpuf

Heart failure with a preserved ejection fraction (HFPEF) is a clinical syndrome that has no pharmacologic therapies approved for this use to date. In light of failed medicines, cardiologists have refocused treatment strategies based on the theory that HFPEF is a heterogeneous clinical syndrome with different etiologies. Classification of HFPEF according to etiologic subtype may, therefore, identify cohorts with treatable pathophysiologic mechanisms and may ultimately pave the way forward for developing meaningful HFPEF therapies.1

A wealth of data now indicates that amyloid infiltration is an important mechanism underlying HFPEF. Inherited mutations in transthyretin cardiac amyloidosis (ATTRm) or the aging process in wild-type disease (ATTRwt) cause destabilization of the transthyretin (TTR) protein into monomers or oligomers, which aggregate into amyloid fibrils. These insoluble fibrils accumulate in the myocardium and result in diastolic dysfunction, restrictive cardiomyopathy, and eventual congestive heart failure (Figure 1). In an autopsy study of HFPEF patients, almost 20% without antemortem suspicion of amyloid had left ventricular (LV) TTR amyloid deposition.2 Even more resounding evidence for the contribution of TTR amyloid to HFPEF was a study in which 120 hospitalized HFPEF patients with LV wall thickness ≥12 mm underwent technetium-99m 3,3-diphosphono-1,2-propranodicarboxylic acid (99mTc-DPD) cardiac imaging,3,4 a bone isotope known to have high sensitivity and specificity for diagnosing TTR cardiac amyloidosis.5,6 Moderate-to-severe myocardial uptake indicative of TTR cardiac amyloid deposition was detected in 13.3% of HFPEF patients who did not have TTR gene mutations. Therefore, TTR cardiac amyloid deposition, especially in older adults, is not rare, can be easily identified, and may contribute to the underlying pathophysiology of HFPEF.

Figure 1

As no U.S. Food and Drug Administration-approved drugs are currently available for the treatment of HFPEF or TTR cardiac amyloidosis, the development of medications that attenuate or prevent TTR-mediated organ toxicity has emerged as an important therapeutic goal. Over the past decade, a host of therapies and therapeutic drug classes have emerged in clinical trials (Table 1), and these may herald a new direction for treating HFPEF secondary to TTR amyloid.

Table 1

TTR Silencers (siRNA and Antisense Oligonucleotides)

siRNA

Ribonucleic acid interference (RNAi) has surfaced as an endogenous cellular mechanism for controlling gene expression. Small interfering RNAs (siRNAs) delivered into cells can disrupt the production of target proteins.7,8 A formulation of lipid nanoparticle and triantennary N-acetylgalactosamine (GalNAc) conjugate that delivers siRNAs to hepatocytes is currently in clinical trials.9 Prior research demonstrated these GalNAc-siRNA conjugates result in robust and durable knockdown of a variety of hepatocyte targets across multiple species and appear to be well suited for suppression of TTR gene expression and subsequent TTR protein production.

The TTR siRNA conjugated to GalNAc, ALN-TTRSc, is now under active investigation as a subcutaneous injection in phase 3 clinical trials in patients with TTR cardiac amyloidosis.10 Prior phase 2 results demonstrated that ALN-TTRSc was generally well tolerated in patients with significant TTR disease burden and that it reduced both wild-type and mutant TTR gene expression by a mean of 87%. Harnessing RNAi technology appears to hold great promise for treating patients with TTR cardiac amyloidosis. The ability of ALN-TTRSc to lower both wild-type and mutant proteins may provide a major advantage over liver transplantation, which affects the production of only mutant protein and is further limited by donor shortage, cost, and need for immunosuppression.

Antisense Oligonucleotides

Antisense oligonucleotides (ASOs) are under clinical investigation for their ability to inhibit hepatic expression of amyloidogenic TTR protein. Currently, the ASO compound, ISIS-TTRRx, is under investigation in a phase 3 multicenter, randomized, double-blind, placebo-controlled clinical trial in patients with familial amyloid polyneuropathy (FAP).11 The primary objective is to evaluate its efficacy as measured by change in neuropathy from baseline relative to placebo. Secondary measures will evaluate quality of life (QOL), modified body mass index (mBMI) by albumin, and pharmacodynamic effects on retinol binding protein. Exploratory objectives in a subset of patients with LV wall thickness ≥13 mm without a history of persistent hypertension will examine echocardiographic parameters, N-terminal pro–B-type natriuretic peptide (NT-proBNP), and polyneuropathy disability score relative to placebo. These data will facilitate analysis of the effect of antisense oligonucleotide-mediated TTR suppression on the TTR cardiac phenotype with a phase 3 trial anticipated to begin enrollment in 2016.

TTR Stabilizers (Diflunisal, Tafamidis)

Diflunisal

Several TTR-stabilizing agents are in various stages of clinical trials. Diflunisal, a traditionally used and generically available nonsteroidal anti-inflammatory drug (NSAID), binds and stabilizes familial TTR variants against acid-mediated fibril formation in vitro and is now in human clinical trials.12,13 The use of diflunisal in patients with TTR cardiac amyloidosis is controversial given complication of chronic inhibition of cyclooxygenase (COX) enzymes, including gastrointestinal bleeding, renal dysfunction, fluid retention, and hypertension that may precipitate or exacerbate heart failure in vulnerable individuals.14-17 In TTR cardiac amyloidosis, an open-label cohort study suggested that low-dose diflunisal with careful monitoring along with a prophylactic proton pump inhibitor could be safely administered to compensated patients.18 An association was observed, however, between chronic diflunisal use and adverse changes in renal function suggesting that advanced kidney disease may be prohibitive in diflunisal therapy.In FAP patients with peripheral or autonomic neuropathy randomized to diflunisal or placebo, diflunisal slowed progression of neurologic impairment and preserved QOL over two years of follow-up.19 Echocardiography demonstrated cardiac involvement in approximately 50% of patients.20 Longer-term safety and efficacy data over an average 38 ± 31 months in 40 Japanese patients with hereditary ATTR amyloidosis who were not candidates for liver transplantation showed that diflunisal was mostly well tolerated.12 The authors cautioned the need for attentive monitoring of renal function and blood cell counts. Larger multicenter collaborations are needed to determine diflunisal’s true efficacy in HFPEF patients with TTR cardiac amyloidosis.

Tafamidis

Tafamidis is under active investigation as a novel compound that binds to the thyroxine-binding sites of the TTR tetramer, inhibiting its dissociation into monomers and blocking the rate-limiting step in the TTR amyloidogenesis cascade.21 The TTR compound was shown in an 18-month double-blind, placebo-controlled trial to slow progression of neurologic symptoms in patients with early-stage ATTRm due to the V30M mutation.22 When focusing on cardiomyopathy in a phase 2, open-label trial, tafamidis also appeared to effectively stabilize TTR tetramers in non-V30M variants, wild-type and V122I, as well as biochemical and echocardiographic parameters.23,24 Preliminary data suggests that clinically stabilized patients had shorter disease duration, lower cardiac biomarkers, less myocardial thickening, and higher EF than those who were not stabilized, suggesting early institution of therapy may be beneficial. A phase 3 trial has completed enrollment and will evaluate the efficacy, safety, and tolerability of tafamidis 20 or 80 mg orally vs. placebo.25 This will contribute to long-term safety and efficacy data needed to determine the therapeutic effects of tafamidis among ATTRm variants.

Amyloid Degraders (Doxycycline/TUDCA and Anti-SAP Antibodies)

Doxycycline/TUDCA

While silencer and stabilizer drugs are aimed at lowering amyloidogenic precursor protein production, they cannot remove already deposited fibrils in an infiltrated heart. Removal of already deposited fibrils by amyloid degraders would be an important therapeutic strategy, particularly in older adults with heavily infiltrated hearts reflected by thick walls, HFPEF, systolic heart failure, and restrictive cardiomyopathy. Combined doxycycline and tauroursodeoxycholic acid (TUDCA) disrupt TTR amyloid fibrils and appeared to have an acceptable safety profile in a small phase 2 open-label study among 20 TTR patients. No serious adverse reactions or clinical progression of cardiac or neuropathic involvement was observed over one year.26 An active phase 2, single-center, open-label, 12-month study will assess primary outcome measures including mBMI, neurologic impairment score, and NT-proBNP.27 Another phase 2 study is examining the tolerability and efficacy of doxycycline/TUDCA over an 18-month period in patients with TTR amyloid cardiomyopathy.28 Additionally, a study in patients with TTR amyloidosis is ongoing to determine the effect of doxycycline alone on neurologic function, cardiac biomarkers, echocardiographic parameters, modified body mass index, and autonomic neuropathy.29

Anti-SAP Antibodies

In order to safely clear established amyloid deposits, the role of the normal, nonfibrillar plasma glycoprotein present in all human amyloid deposits, serum amyloid P component (SAP), needs to be more clearly understood.30 In mice with amyloid AA type deposits, administration of antihuman SAP antibody triggered a potent giant cell reaction that removed massive visceral amyloid deposits without adverse effects.31 In humans with TTR cardiac amyloidosis, anti-SAP antibody treatments could be feasible because the bis-D proline compound, CPHPC, is capable of clearing circulating human SAP, which allow anti-SAP antibodies to reach residual deposited SAP. In a small, open-label, single-dose-escalation, phase 1 trial involving 15 patients with systemic amyloidosis, none of whom had clinical evidence of cardiac amyloidosis, were treated with CPHPC followed by human monoclonal IgG1 anti-SAP antibody.32 No serious adverse events were reported and amyloid deposits were cleared from the liver, kidney, and lymph node. Anti-SAP antibodies hold promise as a potential amyloid therapy because of their potential to target all forms of amyloid deposits across multiple tissue types.

Mutant or wild-type TTR cardiac amyloidoses are increasingly recognized as a cause of HFPEF. Clinicians need to be aware of this important HFPEF etiology because the diverse array of emerging disease-modifying agents for TTR cardiac amyloidosis in human clinical trials has the potential to herald a new era for the treatment of HFPEF.

References

  1. Maurer MS, Mancini D. HFpEF: is splitting into distinct phenotypes by comorbidities the pathway forward? J Am Coll Cardiol 2014;64:550-2.
  2. Mohammed SF, Mirzoyev SA, Edwards WD, et al. Left ventricular amyloid deposition in patients with heart failure and preserved ejection fraction. JACC Heart Fail 2014;2:113-22.
  3. González-López E, Gallego-Delgado M, Guzzo-Merello G, et al. Wild-type transthyretin amyloidosis as a cause of heart failure with preserved ejection fraction. Eur Heart J 2015.
  4. Castano A, Bokhari S, Maurer MS. Unveiling wild-type transthyretin cardiac amyloidosis as a significant and potentially modifiable cause of heart failure with preserved ejection fraction. Eur Heart J 2015 Jul 28. [Epub ahead of print]
  5. Rapezzi C, Merlini G, Quarta CC, et al. Systemic cardiac amyloidoses: disease profiles and clinical courses of the 3 main types. Circulation 2009;120:1203-12.
  6. Bokhari S, Castano A, Pozniakoff T, Deslisle S, Latif F, Maurer MS. (99m)Tc-pyrophosphate scintigraphy for differentiating light-chain cardiac amyloidosis from the transthyretin-related familial and senile cardiac amyloidoses. Circ Cardiovasc Imaging 2013;6:195-201.
  7. Fire A, Xu S, Montgomery MK, Kostas SA, Driver SE, Mello CC. Potent and specific genetic interference by double-stranded RNA in Caenorhabditis elegans. Nature 1998;391:806-11.
  8. Elbashir SM, Harborth J, Lendeckel W, Yalcin A, Weber K, Tuschl T. Duplexes of 21-nucleotide RNAs mediate RNA interference in cultured mammalian cells. Nature 2001;411:494-8.
  9. Kanasty R, Dorkin JR, Vegas A, Anderson D. Delivery materials for siRNA therapeutics. Nature Mater 2013;12:967-77.
  10. U.S. National Institutes of Health. Phase 2 Study to Evaluate ALN-TTRSC in Patients With Transthyretin (TTR) Cardiac Amyloidosis (ClinicalTrials.gov website). 2014. Available at: https://www.clinicaltrials.gov/ct2/show/NCT01981837. Accessed 8/19/2015.
  11. U.S. National Institutes of Health. Efficacy and Safety of ISIS-TTRRx in Familial Amyloid Polyneuropathy (Clinical Trials.gov Website. 2013. Available at: http://www.clinicaltrials.gov/ct2/show/NCT01737398. Accessed 8/19/2015.
  12. Sekijima Y, Dendle MA, Kelly JW. Orally administered diflunisal stabilizes transthyretin against dissociation required for amyloidogenesis. Amyloid 2006;13:236-49.
  13. Tojo K, Sekijima Y, Kelly JW, Ikeda S. Diflunisal stabilizes familial amyloid polyneuropathy-associated transthyretin variant tetramers in serum against dissociation required for amyloidogenesis. Neurosci Res 2006;56:441-9.
  14. Epstein M. Non-steroidal anti-inflammatory drugs and the continuum of renal dysfunction. J Hypertens Suppl 2002;20:S17-23.
  15. Wallace JL. Pathogenesis of NSAID-induced gastroduodenal mucosal injury. Best Pract Res Clin Gastroenterol 2001;15:691-703.
  16. Mukherjee D, Nissen SE, Topol EJ. Risk of cardiovascular events associated with selective COX-2 inhibitors. JAMA 2001;286:954-9.
  17. Page J, Henry D. Consumption of NSAIDs and the development of congestive heart failure in elderly patients: an underrecognized public health problem. Arch Intern Med 2000;160:777-84.
  18. Castano A, Helmke S, Alvarez J, Delisle S, Maurer MS. Diflunisal for ATTR cardiac amyloidosis. Congest Heart Fail 2012;18:315-9.
  19. Berk JL, Suhr OB, Obici L, et al. Repurposing diflunisal for familial amyloid polyneuropathy: a randomized clinical trial. JAMA 2013;310:2658-67.
  20. Quarta CCF, Solomon RH Suhr SD, et al. The prevalence of cardiac amyloidosis in familial amyloidotic polyneuropathy with predominant neuropathy: The Diflunisal Trial. International Symposium on Amyloidosis 2014:88-9.
  21. Hammarstrom P, Jiang X, Hurshman AR, Powers ET, Kelly JW. Sequence-dependent denaturation energetics: A major determinant in amyloid disease diversity. Proc Natl Acad Sci U S A 2002;99 Suppl 4:16427-32.
  22. Coelho T, Maia LF, Martins da Silva A, et al. Tafamidis for transthyretin familial amyloid polyneuropathy: a randomized, controlled trial. Neurology 2012;79:785-92.
  23. Merlini G, Plante-Bordeneuve V, Judge DP, et al. Effects of tafamidis on transthyretin stabilization and clinical outcomes in patients with non-Val30Met transthyretin amyloidosis. J Cardiovasc Transl Res 2013;6:1011-20.
  24. Maurer MS, Grogan DR, Judge DP, et al. Tafamidis in transthyretin amyloid cardiomyopathy: effects on transthyretin stabilization and clinical outcomes. Circ Heart Fail 2015;8:519-26.
  25. U.S. National Institutes of Health. Safety and Efficacy of Tafamidis in Patients With Transthyretin Cardiomyopathy (ATTR-ACT) (ClinicalTrials.gov website). 2014. Available at: http://www.clinicaltrials.gov/show/NCT01994889. Accessed 8/19/2015.
  26. Obici L, Cortese A, Lozza A, et al. Doxycycline plus tauroursodeoxycholic acid for transthyretin amyloidosis: a phase II study. Amyloid 2012;19 Suppl 1:34-6.
  27. U.S. National Institutes of Health. Safety, Efficacy and Pharmacokinetics of Doxycycline Plus Tauroursodeoxycholic Acid in Transthyretin Amyloidosis (ClinicalTrials.gov website). 2011. Available at: http://www.clinicaltrials.gov/ct2/show/NCT01171859. Accessed 8/19/2015.
  28. U.S. National Institutes of Health. Tolerability and Efficacy of a Combination of Doxycycline and TUDCA in Patients With Transthyretin Amyloid Cardiomyopathy (ClinicalTrials.gov website). 2013. Available at: http://www.clinicaltrials.gov/ct2/show/NCT01855360. Accessed 8/19/2015.
  29. U.S. National Institutes of Health. Safety and Effect of Doxycycline in Patients With Amyloidosis (ClinicalTrials.gov website).2015. Available at: https://clinicaltrials.gov/ct2/show/NCT01677286. Accessed 8/19/2015.
  30. Pepys MB, Dash AC. Isolation of amyloid P component (protein AP) from normal serum as a calcium-dependent binding protein. Lancet 1977;1:1029-31.
  31. Bodin K, Ellmerich S, Kahan MC, et al. Antibodies to human serum amyloid P component eliminate visceral amyloid deposits. Nature 2010;468:93-7.
  32. Richards DB, Cookson LM, Berges AC, et al. Therapeutic Clearance of Amyloid by Antibodies to Serum Amyloid P Component. N Engl J Med 2015;373:1106-14.

 

The Acid-Mediated Denaturation Pathway of Transthyretin Yields a Conformational Intermediate That Can Self-Assemble into Amyloid

Zhihong Lai , Wilfredo Colón , and Jeffery W. Kelly *
Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255
Biochemistry199635 (20), pp 6470–6482   http://dx.doi.org:/10.1021/bi952501g
Publication Date (Web): May 21, 1996  Copyright © 1996 American Chemical Society

Transthyretin (TTR) amyloid fibril formation is observed during partial acid denaturation and while refolding acid-denatured TTR, implying that amyloid fibril formation results from the self-assembly of a conformational intermediate. The acid denaturation pathway of TTR has been studied in detail herein employing a variety of biophysical methods to characterize the intermediate(s) capable of amyloid fibril formation. At physiological concentrations, tetrameric TTR remains associated from pH 7 to pH 5 and is incapable of amyloid fibril formation. Tetrameric TTR dissociates to a monomer in a process that is dependent on both pH and protein concentration below pH 5. The extent of amyloid fibril formation correlates with the concentration of the TTR monomer having an altered, but defined, tertiary structure over the pH range of 5.0−3.9. The inherent Trp fluorescence-monitored denaturation curve of TTR exhibits a plateau over the pH range where amyloid fibril formation is observed (albeit at a higher concentration), implying that a steady-state concentration of the amyloidogenic intermediate with an altered tertiary structure is being detected. Interestingly, 1-anilino-8-naphthalenesulfonate fluorescence is at a minimum at the pH associated with maximal amyloid fibril formation (pH 4.4), implying that the amyloidogenic intermediate does not have a high extent of hydrophobic surface area exposed, consistent with a defined tertiary structure. Transthyretin has two Trp residues in its primary structure, Trp-41 and Trp-79, which are conveniently located far apart in the tertiary structure of TTR. Replacement of each Trp with Phe affords two single Trp containing variants which were used to probe local pH-dependent tertiary structural changes proximal to these chromophores. The pH-dependent fluorescence behavior of the Trp-79-Phe mutant strongly suggests that Trp-41 is located near the site of the tertiary structural rearrangement that occurs in the formation of the monomeric amyloidogenic intermediate, likely involving the C-strand−loop−D-strand region. Upon further acidification of TTR (below pH 4.4), the structurally defined monomeric amyloidogenic intermediate begins to adopt alternative conformations that are not amyloidogenic, ultimately forming an A-state conformation below pH 3 which is also not amyloidogenic. In summary, analytical equilibrium ultracentrifugation, SDS−PAGE, far- and near-UV CD, fluorescence, and light scattering studies suggest that the amyloidogenic intermediate is a monomeric predominantly β-sheet structure having a well-defined tertiary structure.

 

Prevention of Transthyretin Amyloid Disease by Changing Protein Misfolding Energetics

Per Hammarström*, R. Luke Wiseman*, Evan T. Powers, Jeffery W. Kelly   + Author Affiliations

Science  31 Jan 2003; 299(5607):713-716   http://dx.doi.org:/10.1126/science.1079589

Genetic evidence suggests that inhibition of amyloid fibril formation by small molecules should be effective against amyloid diseases. Known amyloid inhibitors appear to function by shifting the aggregation equilibrium away from the amyloid state. Here, we describe a series of transthyretin amyloidosis inhibitors that functioned by increasing the kinetic barrier associated with misfolding, preventing amyloidogenesis by stabilizing the native state. The trans-suppressor mutation, threonine 119 → methionine 119, which is known to ameliorate familial amyloid disease, also functioned through kinetic stabilization, implying that this small-molecule strategy should be effective in treating amyloid diseases.

 

Rational design of potent human transthyretin amyloid disease inhibitors

Thomas Klabunde1,2, H. Michael Petrassi3, Vibha B. Oza3, Prakash Raman3, Jeffery W. Kelly3 & James C. Sacchettini1

Nature Structural & Molecular Biology 2000; 7: 312 – 321.                http://dx.doi.org:/10.1038/74082

The human amyloid disorders, familial amyloid polyneuropathy, familial amyloid cardiomyopathy and senile systemic amyloidosis, are caused by insoluble transthyretin (TTR) fibrils, which deposit in the peripheral nerves and heart tissue. Several nonsteroidal anti-inflammatory drugs and structurally similar compounds have been found to strongly inhibit the formation of TTR amyloid fibrils in vitro. These include flufenamic acid, diclofenac, flurbiprofen, and resveratrol. Crystal structures of the protein–drug complexes have been determined to allow detailed analyses of the protein–drug interactions that stabilize the native tetrameric conformation of TTR and inhibit the formation of amyloidogenic TTR. Using a structure-based drug design approach ortho-trifluormethylphenyl anthranilic acid and N-(meta-trifluoromethylphenyl) phenoxazine 4,6-dicarboxylic acid have been discovered to be very potent and specific TTR fibril formation inhibitors. This research provides a rationale for a chemotherapeutic approach for the treatment of TTR-associated amyloid diseases.

 

First European consensus for diagnosis, management, and treatment of transthyretin familial amyloid polyneuropathy

Adams, Davida; Suhr, Ole B.b; Hund, Ernstc; Obici, Laurad; Tournev, Ivailoe,f; Campistol, Josep M.g; Slama, Michel S.h; Hazenberg, Bouke P.i; Coelho, Teresaj; from the European Network for TTR-FAP (ATTReuNET)

Current Opin Neurol: Feb 2016; 29 – Issue – p S14–S26      http://dx.doi.org:/10.1097/WCO.0000000000000289

Purpose of review: Early and accurate diagnosis of transthyretin familial amyloid polyneuropathy (TTR-FAP) represents one of the major challenges faced by physicians when caring for patients with idiopathic progressive neuropathy. There is little consensus in diagnostic and management approaches across Europe.

Recent findings: The low prevalence of TTR-FAP across Europe and the high variation in both genotype and phenotypic expression of the disease means that recognizing symptoms can be difficult outside of a specialized diagnostic environment. The resulting delay in diagnosis and the possibility of misdiagnosis can misguide clinical decision-making and negatively impact subsequent treatment approaches and outcomes.

Summary: This review summarizes the findings from two meetings of the European Network for TTR-FAP (ATTReuNET). This is an emerging group comprising representatives from 10 European countries with expertise in the diagnosis and management of TTR-FAP, including nine National Reference Centres. The current review presents management strategies and a consensus on the gold standard for diagnosis of TTR-FAP as well as a structured approach to ongoing multidisciplinary care for the patient. Greater communication, not just between members of an individual patient’s treatment team, but also between regional and national centres of expertise, is the key to the effective management of TTR-FAP.

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Transthyretin familial amyloid polyneuropathy (TTR-FAP) is a highly debilitating and irreversible neurological disorder presenting symptoms of progressive sensorimotor and autonomic neuropathy [1▪,2▪,3]. TTR-FAP is caused by misfolding of the transthyretin (TTR) protein leading to protein aggregation and the formation of amyloid fibrils and, ultimately, to amyloidosis (commonly in the peripheral and autonomic nervous system and the heart) [4,5]. TTR-FAP usually proves fatal within 7–12 years from the onset of symptoms, most often due to cardiac dysfunction, infection, or cachexia [6,7▪▪].

The prevalence and disease presentation of TTR-FAP vary widely within Europe. In endemic regions (northern Portugal, Sweden, Cyprus, and Majorca), patients tend to present with a distinct genotype in large concentrations, predominantly a Val30Met substitution in the TTR gene [8–10]. In other areas of Europe, the genetic footprint of TTR-FAP is more varied, with less typical phenotypic expression [6,11]. For these sporadic or scattered cases, a lack of awareness among physicians of variable clinical features and limited access to diagnostic tools (i.e., pathological studies and genetic screening) can contribute to high rates of misdiagnosis and poorer patient outcomes [1▪,11]. In general, early and late-onset variants of TTR-FAP, found within endemic and nonendemic regions, present several additional diagnostic challenges [11,12,13▪,14].

Delay in the time to diagnosis is a major obstacle to the optimal management of TTR-FAP. With the exception of those with a clearly diagnosed familial history of FAP, patients still invariably wait several years between the emergence of first clinical signs and accurate diagnosis [6,11,14]. The timely initiation of appropriate treatment is particularly pertinent, given the rapidity and irreversibility with which TTR-FAP can progress if left unchecked, as well as the limited effectiveness of available treatments during the later stages of the disease [14]. This review aims to consolidate the existing literature and present an update of the best practices in the management of TTR-FAP in Europe. A summary of the methods used to achieve a TTR-FAP diagnosis is presented, as well as a review of available treatments and recommendations for treatment according to disease status.

Patients with TTR-FAP can present with a range of symptoms [11], and care should be taken to acquire a thorough clinical history of the patient as well as a family history of genetic disease. Delay in diagnosis is most pronounced in areas where TTR-FAP is not endemic or when there is no positive family history [1▪]. TTR-FAP and TTR-familial amyloid cardiomyopathy (TTR-FAC) are the two prototypic clinical disease manifestations of a broader disease spectrum caused by an underlying hereditary ATTR amyloidosis [19]. In TTR-FAP, the disease manifestation of neuropathy is most prominent and definitive for diagnosis, whereas cardiomyopathy often suggests TTR-FAC. However, this distinction is often superficial because cardiomyopathy, autonomic neuropathy, vitreous opacities, kidney disease, and meningeal involvement all may be present with varying severity for each patient with TTR-FAP.

Among early onset TTR-FAP with usually positive family history, symptoms of polyneuropathy present early in the disease process and usually predominate throughout the progression of the disease, making neurological testing an important diagnostic aid [14]. Careful clinical examination (e.g., electromyography with nerve conduction studies and sympathetic skin response, quantitative sensation test, quantitative autonomic test) can be used to detect, characterize, and scale the severity of neuropathic abnormalities involving small and large nerve fibres [10]. Although a patient cannot be diagnosed definitively with TTR-FAP on the basis of clinical presentation alone, symptoms suggesting the early signs of peripheral neuropathy, autonomic dysfunction, and cardiac conduction disorders or infiltrative cardiomyopathy are all indicators that further TTR-FAP diagnostic investigation is warranted. Late-onset TTR-FAP often presents as sporadic cases with distinct clinical features (e.g., milder autonomic dysfunction) and can be more difficult to diagnose than early-onset TTR-FAP (Table 2) [1▪,11,12,13▪,14,20].

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Genetic testing is carried out to allow detection of specific amyloidogenic TTR mutations (Table 1), using varied techniques depending on the expertise and facilities available in each country (Table S2, http://links.lww.com/CONR/A39). A targeted approach to detect a specific mutation can be used for cases belonging to families with previous diagnosis. In index cases of either endemic and nonendemic regions that do not have a family history of disease, are difficult to confirm, and have atypical symptoms, TTR gene sequencing is required for the detection of both predicted and new amyloidogenic mutations [26,27].

Following diagnosis, the neuropathy stage and systemic extension of the disease should be determined in order to guide the next course of treatment (Table 4) [3,30,31]. The three stages of TTR-FAP severity are graded according to a patient’s walking disability and degree of assistance required [30]. Systemic assessment, especially of the heart, eyes, and kidney, is also essential to ensure all aspects of potential impact of the disease can be detected [10].

Table 4

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The goals of cardiac investigations are to detect serious conduction disorders with the risk of sudden death and infiltrative cardiomyopathy. Electrocardiograms (ECG), Holter-ECG, and intracardiac electrophysiology study are helpful to detect conduction disorders. Echocardiograms, cardiac magnetic resonance imaging, scintigraphy with bone tracers, and biomarkers (e.g., brain natriuretic peptide, troponin) can all help to diagnose infiltrative cardiomyopathy[10]. An early detection of cardiac abnormalities has obvious benefits to the patient, given that the prophylactic implantation of pacemakers was found to prevent 25% of major cardiac events in TTR-FAP patients followed up over an average of 4 years [32▪▪]. Assessment of cardiac denervation with 123-iodine meta-iodobenzylguanidine is a powerful prognostic marker in patients diagnosed with FAP [33].

…..

Tafamidis

Tafamidis is a first-in-class therapy that slows the progression of TTR amyloidogenesis by stabilizing the mutant TTR tetramer, thereby preventing its dissociation into monomers and amyloidogenic and toxic intermediates [55,56]. Tafamidis is currently indicated in Europe for the treatment of TTR amyloidosis in adult patients with stage I symptomatic polyneuropathy to delay peripheral neurological impairment [57].

In an 18-month, double-blind, placebo-controlled study of patients with early-onset Val30Met TTR-FAP, tafamidis was associated with a 52% lower reduction in neurological deterioration (P = 0.027), a preservation of nerve function, and TTR stabilization versus placebo [58▪▪]. However, only numerical differences were found for the coprimary endpoints of neuropathy impairment [neuropathy impairment score in the lower limb (NIS-LL) responder rates of 45.3% tafamidis vs 29.5% placebo; P = 0.068] and quality of life scores [58▪▪]. A 12-month, open-label extension study showed that the reduced rates of neurological deterioration associated with tafamidis were sustained over 30 months, with earlier initiation of tafamidis linking to better patient outcomes (P = 0.0435) [59▪]. The disease-slowing effects of tafamidis may be dependent on the early initiation of treatment. In an open-label study with Val30Met TTR-FAP patients with late-onset and advanced disease (NIS-LL score >10, mean age 56.4 years), NIS-LL and disability scores showed disease progression despite 12 months of treatment with tafamidis, marked by a worsening of neuropathy stage in 20% and the onset of orthostatic hypotension in 22% of patients at follow-up [60▪].

Tafamidis is not only effective in patients exhibiting the Val30Met mutation; it also has proven efficacy, in terms of TTR stabilization, in non-Val30Met patients over 12 months [61]. Although tafamidis has demonstrated safe use in patients with TTR-FAP, care should be exercised when prescribing to those with existing digestive problems (e.g., diarrhoea, faecal incontinence) [60▪].

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Diflunisal

Diflunisal is a nonsteroidal anti-inflammatory drug (NSAID) that, similar to tafamidis, slows the rate of amyloidogenesis by preventing the dissociation, misfolding, and misassembly of the mutated TTR tetramer [62,63]. Off-label use has been reported for patients with stage I and II disease, although diflunisal is not currently licensed for the treatment of TTR-FAP.

Evidence for the clinical effectiveness of diflunisal in TTR-FAP derives from a placebo-controlled, double-blind, 24-month study in 130 patients with clinically detectable peripheral or autonomic neuropathy[64▪]. The deterioration in NIS scores was significantly more pronounced in patients receiving placebo compared with those taking diflunisal (P = 0.001), and physical quality of life measures showed significant improvement among diflunisal-treated patients (P = 0.001). Notable during this study was the high rate of attrition in the placebo group, with 50% more placebo-treated patients dropping out of this 2-year study as a result of disease progression, advanced stage of the disease, and varied mutations.

One retrospective analysis of off-label use of diflunisal in patients with TTR-FAP reported treatment discontinuation in 57% of patients because of adverse events that were largely gastrointestinal [65]. Conclusions on the safety of diflunisal in TTR-FAP will depend on further investigations on the impact of known cardiovascular and renal side-effects associated with the NSAID drug class [66,67].

 

 

 

 

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Long noncoding RNA has role in brain development

Curator: Larry H. Bernstein, MD, FCAP

LPBI

 

Brain Power

6/06/2016 – by University of California, Santa Barbara

http://www.biosciencetechnology.com/news/2016/06/brain-power

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Compared to other mammals, humans have the largest cerebral cortex. A sheet of brain cells that folds in on itself multiple times in order to fit inside the skull, the cortex is the seat of higher functions. It is what enables us to process everything we see and hear and think.

The expansion of the cerebral cortex sets humans apart from the rest of their fellow primates. Yet scientists have long wondered what mechanisms are responsible for this evolutionary development.

New research from the Kosik Molecular and Cellular Neurobiology Lab at UC Santa Barbara has pinpointed a specific long nocoding ribonucleic acid (lncRNA) that regulates neural development (ND). The findings appear in the journal Neuron.

“This lncND, as we’ve called it, can be found only in the branch of primates that leads to humans. It is a stretch of nucleotides that does not code a protein,” said senior author Kenneth S. Kosik, the Harriman Professor of Neuroscience Research in UCSB’s Department of Molecular, Cellular, and Developmental Biology. “We demonstrate that lncND is turned on during development and turned off when the cell matures.”

Lead author Neha Rani, a postdoctoral scholar in the Kosik Lab, idenfitied several binding sites on lncND for another type of RNA called a microRNA. One of them, called microRNA-143, binds to lncND.

“We found that lncND could sequester this microRNA and in doing so regulate the expression of Notch proteins,” Rani said. “Notch proteins are very important regulators during neuronal development. They are involved in cell differentiation and cell fate and are critical in the neural development pathway.”

Kosik describes lncND as a platform that binds these microRNAs like a sponge. “This allows Notch to do what it’s supposed to do during development,” he explained. “Then as the brain matures, levels of lncND go down and when they do, those microRNAs come flying off the platform and glom onto Notch to bring its levels down. You want Notch levels to be high while the brain is developing but not once maturation occurs. This lncND is an elegant way to change Notch levels quickly.”

To replicate these cell culture results, Rani used human stem cells to grow neurons into what is called a mini brain. In this pea-sized gob of brain tissue, she identified a subpopulation — radial glial cells (neuronal stem cells) and other neural progenitors — responsible for making lncND.

But the researchers wanted to see the radial glial cells in actual human brain tissue, so they turned to colleagues in the Developmental & Stem Cell Biology Graduate Program at the UC San Francisco School of Medicine. Using in situ hybridization, UCSF scientists found lncND in neural precursor cells but not in mature neurons.

“It was right where we thought it would be in brain tissue,” said Kosik, who is also the co-director of UCSB’s Neuroscience Research Institute. “But we still had one more thing we had to do because people would still not be satisfied that we had done everything possible to show that lncND was really doing something functionally.”

So the UCSF team introduced lncND into the fetal brain of a gestating mouse. Green fluorescent protein labeling allowed them to see the early development pattern and show that lncND, which ordinarily is not present in mice — lncND is present only in some primates including humans — had a functional effect on development.

“When we overexpressed lncND in the mouse fetus, we actually affected development in the predicted manner,” Kosik said. “The early developmental pattern was shifted toward more precursor cells, even though the mouse does not make lncND at all.”

According to Kosik, this work not only identifies a very critical gene for human brain development but also offers a clue about a component that likely contributed to brain expansion in humans. “We have shown that lncND might be an important player in human brain expansion, which is exciting in itself,” Rani said. “Another interesting aspect of this work is that lncND appears to help regulate the key developmental pathway of Notch signaling.”

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New Studies toward Understanding Alzheimer Disease

Curators: Larry H. Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

 

There is no unifying concept of Alzheimer Disease beyond the Tau and beta amyloid roles.  Recently, Ingenbleek and Bernstein (journal AD) made the connection between the age related decline of liver synthesis of plasma transthyretin and the more dramatic decline of transthyretin at the blood brain barrier, and the relationship to inability to transfer vitamin A via retinol binding protein to the brain.  Related metabolic events are reported by several groups.

 

What else is New?

 

Amyloid-β peptide protects against microbial infection in mouse and worm models of Alzheimer’s disease.

Kumar DK, Choi SH, Washicosky KJ, Eimer WA, Tucker S, Ghofrani J, Lefkowitz A, McColl G, Goldstein LE, Tanzi RE, Moir RD.

Sci Transl Med. 2016 May 25;8(340):340ra72.  http://dx.doi.org:/10.1126/scitranslmed.aaf1059

They show that Aβ oligomerization, a behavior traditionally viewed as intrinsically pathological, may be necessary for the antimicrobial activities of the peptide. Collectively, our data are consistent with a model in which soluble Aβ oligomers first bind to microbial cell wall carbohydrates via a heparin-binding domain. Developing protofibrils inhibited pathogen adhesion to host cells. Propagating β-amyloid fibrils mediate agglutination and eventual entrapment of unatttached microbes….Salmonella Typhimurium bacterial infection of the brains of transgenic 5XFAD mice resulted in rapid seeding and accelerated β-amyloid deposition, which closely colocalized with the invading bacteria.

This is quite interesting in that infection drives the production of acute phase reactants resulting in decreased production of transthyretin.  Whether this also has ties to chronic disease in the elderly and risk of AD is not known.

Gain-of-function mutations in protein kinase Cα (PKCα) may promote synaptic defects in Alzheimer’s disease.

Alfonso SI, Callender JA, Hooli B, Antal CE, Mullin K, Sherman MA, Lesné SE, Leitges M, Newton AC, Tanzi RE, Malinow R.

Sci Signal. 2016 May 10;9(427):ra47.  http://dx.doi.org:/10.1126/scisignal.aaf6209.

Through whole-genome sequencing of 1345 individuals from 410 families with late-onset AD (LOAD), they identified three highly penetrant variants in PRKCA, the gene that encodes protein kinase Cα (PKCα), in five of the families. All three variants linked with LOAD displayed increased catalytic activity relative to wild-type PKCα as assessed in live-cell imaging experiments using a genetically encoded PKC activity reporter. Deleting PRKCA in mice or adding PKC antagonists to mouse hippocampal slices infected with a virus expressing the Aβ precursor CT100 revealed that PKCα was required for the reduced synaptic activity caused by Aβ. In PRKCA(-/-) neurons expressing CT100, introduction of PKCα, but not PKCα lacking a PDZ interaction moiety, rescued synaptic depression, suggesting that a scaffolding interaction bringing PKCα to the synapse is required for its mediation of the effects of Aβ. Thus, enhanced PKCα activity may contribute to AD, possibly by mediating the actions of Aβ on synapses.

 

Science Signaling Podcast for 10 May 2016: PKCα in Alzheimer’s disease.

Newton AC, Tanzi RE, VanHook AM.

Sci Signal. 2016 May 10;9(427):pc11. doi: 10.1126/scisignal.aaf9436.

Relevance of the COPI complex for Alzheimer’s disease progression in vivo.

Bettayeb K, Hooli BV, Parrado AR, Randolph L, Varotsis D, Aryal S, Gresack J,Tanzi RE, Greengard P, Flajolet M.

Proc Natl Acad Sci U S A. 2016 May 10;113(19):5418-23. http://dx.doi.org:/10.1073/pnas.1604176113

Inhibition of death-associated protein kinase 1 attenuates the phosphorylation and amyloidogenic processing of amyloid precursor protein.

Kim BM, You MH, Chen CH, Suh J, Tanzi RE, Ho Lee T.

Hum Mol Genet. 2016 Apr 19. pii: ddw114.

Extracellular deposition of amyloid-beta (Aβ) peptide, a metabolite of sequential cleavage of amyloid precursor protein (APP), is a critical step in the pathogenesis of Alzheimer’s disease (AD). While death-associated protein kinase 1 (DAPK1) is highly expressed in AD brains and its genetic variants are linked to AD risk, little is known about the impact of DAPK1 on APP metabolism and Aβ generation. This study demonstrated a novel effect of DAPK1 in the regulation of APP processing using cell culture and mouse models. DAPK1, but not its kinase deficient mutant (K42A), significantly increased human Aβ secretion in neuronal cell culture models. Moreover, knockdown of DAPK1 expression or inhibition of DAPK1 catalytic activity significantly decreased Aβ secretion. Furthermore, DAPK1, but not K42A, triggered Thr668 phosphorylation of APP, which may initiate and facilitate amyloidogenic APP processing leading to the generation of Aβ. In Tg2576 APPswe-overexpressing mice, knockout of DAPK1 shifted APP processing toward non-amyloidogenic pathway and decreased Aβ generation. Finally, in AD brains, elevated DAPK1 levels showed co-relation with the increase of APP phosphorylation. Combined together, these results suggest that DAPK1 promotes the phosphorylation and amyloidogenic processing of APP, and that may serve a potential therapeutic target for AD.

Recapitulating amyloid β and tau pathology in human neural cell culture models: clinical implications.

Choi SH, Kim YH, D’Avanzo C, Aronson J, Tanzi RE, Kim DY.

US Neurol. 2015 Fall;11(2):102-105.    Free PMC Article

The “amyloid β hypothesis” of Alzheimer’s disease (AD) has been the reigning hypothesis explaining pathogenic mechanisms of AD over the last two decades. However, this hypothesis has not been fully validated in animal models, and several major unresolved issues remain. Our 3D human neural cell culture model system provides a premise for a new generation of cellular AD models that can serve as a novel platform for studying pathogenic mechanisms and for high-throughput drug screening in a human brain-like environment.

The two key pathological hallmarks of AD are senile plaques (amyloid plaques) and neurofibrillary tangles (NFTs), which develop in brain regions responsible for memory and cognitive functions (i.e. cerebral cortex and limbic system) 3. Senile plaques are extracellular deposits of amyloid-β (Aβ) peptides, while NFTs are intracellular, filamentous aggregates of hyperphosphorylated tau protein 4.

The identification of Aβ as the main component of senile plaques by Drs. Glenner and Wong in 1984 5 resulted in the original formation of the “amyloid hypothesis.” According to this hypothesis, which was later renamed the “amyloid-β cascade hypothesis” by Drs. Hardy and Higgins 6, the accumulation of Aβ is the initial pathological trigger in the disease, subsequently leading to hyperphosphorylation of tau, causing NFTs, and ultimately, neuronal death and dementia 4,710. Although the details have been modified to reflect new findings, the core elements of this hypothesis remain unchanged: excess accumulation of the pathogenic forms of Aβ, by altered Aβ production and/or clearance, triggers the vicious pathogenic cascades that eventually lead to NFTs and neuronal death.

Over the last two decades, the Aβ hypothesis of AD has reigned, providing the foundation for numerous basic studies and clinical trials 4,7,10,11. According to this hypothesis, the accumulation of Aβ, either by altered Aβ production and/or clearance, is the initial pathological trigger in the disease. The excess accumulation of Aβ then elicits a pathogenic cascade including synaptic deficits, altered neuronal activity, inflammation, oxidative stress, neuronal injury, hyperphosphorylation of tau causing NFTs and ultimately, neuronal death and dementia 4,710.

One of the major unresolved issues of the Aβ hypothesis is to show a direct causal link between Aβ and NFTs 1214. Studies have demonstrated that treatments with various forms of soluble Aβ oligomers induced synaptic deficits and neuronal injury, as well as hyperphosphorylation of tau proteins, in mouse and rat neurons, which could lead to NFTs and neurodegeneration in vivo 1821. However, transgenic AD mouse models carrying single or multiple human familial AD (FAD) mutations in amyloid precursor protein (APP) and/or presenilin 1 (PS1) do not develop NFTs or robust neurodegeneration as observed in human patients, despite robust Aβ deposition 13,22,23. Double and triple transgenic mouse models, harboring both FAD and tau mutations linked with frontotemporal dementia (FTD), are the only rodent models to date displaying both amyloid plaques and NFTs. However, the NFT pathology in these models stems mainly from the overexpression of human tau as a result of the FTD, rather than the FAD mutations24,25.

Human neurons carrying FAD mutations are an optimal model to test whether elevated levels of pathogenic Aβ trigger pathogenic cascades including NFTs, since those cells truly share the same genetic background that induces FAD in humans. Indeed, Israel et al., observed elevated tau phosphorylation in neurons with an APP duplication FAD mutation 33. Blocking Aβ generation by β-secretase inhibitors significantly decreased tau phosphorylation in the same model, but γ-secretase inhibitor, another Aβ blocker, did not affect tau phosphorylation 33. Neurons with the APP V717I FAD mutation also showed an increase in levels of phospho tau and total tau levels 28. More importantly, Muratore and colleagues showed that treatments with Aβ-neutralizing antibodies in those cells significantly reduced the elevated total and phospho tau levels at the early stages of differentiation, suggesting that blocking pathogenic Aβ can reverse the abnormal tau accumulation in APP V717I neurons 28.

Recently, Moore et al. also reported that neurons harboring the APP V717I or the APP duplication FAD mutation showed increases in both total and phospho tau levels 27. Interestingly, altered tau levels were not detected in human neurons carrying PS1 FAD mutations, which significantly increased pathogenic Aβ42 species in the same cells 27. These data suggest that elevated tau levels in these models were not due to extracellular Aβ accumulation but may possibly represent a very early stage of tauopathy. It may also be due to developmental alterations induced by the APP FAD mutations.

As summarized, most human FAD neurons showed significant increases in pathogenic Aβ species, while only APP FAD neurons showed altered tau metabolism that may represent very early stages of tauopathy. However, all of these human FAD neurons failed to recapitulate robust extracellular amyloid plaques, NFTs, or any signs of neuronal death, as predicted in the amyloid hypothesis.

In our recent study, we moved one step closer to proving the amyloid hypothesis. By generating human neural stem cell lines carrying multiple mutations in APP together with PS1, we achieved high levels of pathogenic Aβ42 comparable to those in brains of AD patients 4446.

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Platform for AD drug screening in human neural progenitor cells with FAD mutations in a 3D culture system, which successfully reproduce human AD pathogenesis (amyloid plaques-driven tauopathy).

In addition to the impact on toxic Aβ species, our 3D culture model can test if these antibodies can block tau pathologies in 3D human neural cell culture systems 4446. Human cellular AD models can also be used to determine optimal doses of candidate AD drugs to block Aβ and/or tau pathology without affecting neuronal survival (Fig. 1).

While much progress has been made, many challenges still lie on the path to creating human neural cell culture models that comprehensively recapitulate pathogenic cascades of AD. A major difficulty lies in reconstituting the brain regions most affected in AD: the hippocampus and specific cortical layers. Recent progress in 3D culture technology, such as “cerebral organoids,” may also be helpful in rebuilding the brain structures that are affected by AD in a dish 52,53. These “cerebral organoids” were able to model various discrete brain regions including human cortical areas 52, which enabled them to reproduce microcephaly, a brain developmental disorder. Similarly, pathogenic cascades of AD may be recapitulated in cortex-like structures using this model. Adding neuroinflammatory components, such as microglial cells, which are critical in AD pathogenesis, will illuminate the validity of the amyloid β hypothesis. Reconstitution of robust neuronal death stemming from Aβ and tau pathologies will be the next major step in comprehensively recapitulating AD in a cellular model.

 

Family-based association analyses of imputed genotypes reveal genome-wide significant association of Alzheimer’s disease with OSBPL6, PTPRG, and PDCL3.

Herold C, Hooli BV, Mullin K, Liu T, Roehr JT, Mattheisen M, Parrado AR, Bertram L, Lange C, Tanzi RE.

Mol Psychiatry. 2016 Feb 2. http://dx.doi.org:/10.1038/mp.2015.218.

Relationship between ubiquilin-1 and BACE1 in human Alzheimer’s disease and APdE9 transgenic mouse brain and cell-based models.

Natunen T, Takalo M, Kemppainen S, Leskelä S, Marttinen M, Kurkinen KM, Pursiheimo JP, Sarajärvi T, Viswanathan J, Gabbouj S, Solje E, Tahvanainen E, Pirttimäki T, Kurki M, Paananen J, Rauramaa T, Miettinen P, Mäkinen P, Leinonen V, Soininen H, Airenne K, Tanzi RE, Tanila H, Haapasalo A, Hiltunen M.

Neurobiol Dis. 2016 Jan;85:187-205. http://dx.doi.org:/10.1016/j.nbd.2015.11.005.

Accumulation of β-amyloid (Aβ) and phosphorylated tau in the brain are central events underlying Alzheimer’s disease (AD) pathogenesis. Aβ is generated from amyloid precursor protein (APP) by β-site APP-cleaving enzyme 1 (BACE1) and γ-secretase-mediated cleavages. Ubiquilin-1, a ubiquitin-like protein, genetically associates with AD and affects APP trafficking, processing and degradation. Here, we have investigated ubiquilin-1 expression in human brain in relation to AD-related neurofibrillary pathology and the effects of ubiquilin-1 overexpression on BACE1, tau, neuroinflammation, and neuronal viability in vitro in co-cultures of mouse embryonic primary cortical neurons and microglial cells under acute neuroinflammation as well as neuronal cell lines, and in vivo in the brain of APdE9 transgenic mice at the early phase of the development of Aβ pathology. Ubiquilin-1 expression was decreased in human temporal cortex in relation to the early stages of AD-related neurofibrillary pathology (Braak stages 0-II vs. III-IV). There was a trend towards a positive correlation between ubiquilin-1 and BACE1 protein levels. Consistent with this, ubiquilin-1 overexpression in the neuron-microglia co-cultures with or without the induction of neuroinflammation resulted in a significant increase in endogenously expressed BACE1 levels. Sustained ubiquilin-1 overexpression in the brain of APdE9 mice resulted in a moderate, but insignificant increase in endogenous BACE1 levels and activity, coinciding with increased levels of soluble Aβ40 and Aβ42. BACE1 levels were also significantly increased in neuronal cells co-overexpressing ubiquilin-1 and BACE1. Ubiquilin-1 overexpression led to the stabilization of BACE1 protein levels, potentially through a mechanism involving decreased degradation in the lysosomal compartment. Ubiquilin-1 overexpression did not significantly affect the neuroinflammation response, but decreased neuronal viability in the neuron-microglia co-cultures under neuroinflammation. Taken together, these results suggest that ubiquilin-1 may mechanistically participate in AD molecular pathogenesis by affecting BACE1 and thereby APP processing and Aβ accumulation.

Correction to Cathepsin L Mediates the Degradation of Novel APP C-Terminal Fragments.

Wang H, Sang N, Zhang C, Raghupathi R, Tanzi RE, Saunders A.

Biochemistry. 2015 Sep 22;54(37):5781.  http://dx.doi.org:/10.1021/acs.biochem.5b00968. Epub 2015 Sep 8. No abstract available.

Massachusetts Alzheimer’s Disease Research Center: progress and challenges.

Hyman BT, Growdon JH, Albers MW, Buckner RL, Chhatwal J, Gomez-Isla MT, Haass C, Hudry E, Jack CR Jr, Johnson KA, Khachaturian ZS, Kim DY, Martin JB, Nitsch RM, Rosen BR, Selkoe DJ, Sperling RA, St George-Hyslop P, Tanzi RE, Yap L, Young AB, Phelps CH, McCaffrey PG.

Alzheimers Dement. 2015 Oct;11(10):1241-5. http://dx.doi.org:/10.1016/j.jalz.2015.06.1887. Epub 2015 Aug 19. No abstract available.

Alzheimer’s in 3D culture: challenges and perspectives.

D’Avanzo C, Aronson J, Kim YH, Choi SH, Tanzi RE, Kim DY.

Bioessays. 2015 Oct;37(10):1139-48. doi: 10.1002/bies.201500063. Epub 2015 Aug 7. Review.

Synaptotagmins interact with APP and promote Aβ generation.

Gautam V, D’Avanzo C, Berezovska O, Tanzi RE, Kovacs DM.

Mol Neurodegener. 2015 Jul 23;10:31. doi: 10.1186/s13024-015-0028-5.

Near-infrared fluorescence molecular imaging of amyloid beta species and monitoring therapy in animal models of Alzheimer’s disease.

Zhang X, Tian Y, Zhang C, Tian X, Ross AW, Moir RD, Sun H, Tanzi RE, Moore A, Ran C.

Proc Natl Acad Sci U S A. 2015 Aug 4;112(31):9734-9. doi: 10.1073/pnas.1505420112. Epub 2015 Jul 21.

A 3D human neural cell culture system for modeling Alzheimer’s disease.

Kim YH, Choi SH, D’Avanzo C, Hebisch M, Sliwinski C, Bylykbashi E, Washicosky KJ, Klee JB, Brüstle O, Tanzi RE, Kim DY.

Nat Protoc. 2015 Jul;10(7):985-1006. doi: 10.1038/nprot.2015.065. Epub 2015 Jun 11.

Cathepsin L Mediates the Degradation of Novel APP C-Terminal Fragments.

Wang H, Sang N, Zhang C, Raghupathi R, Tanzi RE, Saunders A.

Biochemistry. 2015 May 12;54(18):2806-16. doi: 10.1021/acs.biochem.5b00329. Epub 2015 Apr 28. Erratum in: Biochemistry. 2015 Sep 22;54(37):5781.

γ-Secretase modulators reduce endogenous amyloid β42 levels in human neural progenitor cells without altering neuronal differentiation.

D’Avanzo C, Sliwinski C, Wagner SL, Tanzi RE, Kim DY, Kovacs DM.

FASEB J. 2015 Aug;29(8):3335-41. doi: 10.1096/fj.15-271015. Epub 2015 Apr 22.

PLD3 gene variants and Alzheimer’s disease.

Hooli BV, Lill CM, Mullin K, Qiao D, Lange C, Bertram L, Tanzi RE.

Nature. 2015 Apr 2;520(7545):E7-8. doi: 10.1038/nature14040. No abstract available.

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