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Abstract:

The immune response mechanism is the holy grail of the human defense system for health.   IDO, indolamine 2, 3-dioxygenase, is a key gene for homeostasis of immune responses and producing an enzyme catabolizing the first rate-limiting step in tryptophan degradation metabolism. The hemostasis of immune system is complicated.  In this review, the  properties of IDO such as basic molecular genetics, biochemistry and genesis will be discussed.

IDO belongs to globin gene family to carry oxygen and heme.  The main function and genesis of IDO comes from the immune responses during host-microbial invasion and choice between tolerance and immunegenity.  In human there are three kinds of IDOs, which are IDO1, IDO2, and TDO, with distinguished mechanisms and expression profiles. , IDO mechanism includes three distinguished pathways: enzymatic acts through IFNgamma, non-enzymatic acts through TGFbeta-IFNalpha/IFNbeta and moonlighting acts through AhR/Kyn.

The well understood functional genomics and mechanisms is important to translate basic science for clinical interventions of human health needs. In conclusion, overall purpose is to find a method to manipulate IDO to correct/fix/modulate immune responses for clinical applications.

The first part of the review concerns the basic science information gained overall several years that lay the foundation where translational research scientist should familiar to develop a new technology for clinic. The first connection of IDO and human health came from a very natural event that is protection of pregnancy in human. The focus of the translational medicine is treatment of cancer or prevention/delay cancer by stem cell based Dendritic Cell Vaccine (DCvax) development.

Table of Contents:

  • Abstract

1         Introduction: IDO gene encodes a heme enzyme

2        Location, location, location

3        Molecular genetics

4        Types of IDO:

4.1       IDO1,

4.2       IDO2,

4.3       IDO-like proteins

5        Working mechanisms of IDO

6        Infection Diseases and IDO

7. Conclusion

  1. 1.     Indoleamine 2, 3-dioxygenase (IDO) gene encodes a heme enzyme

IDO is a key homeostatic regulator and confined in immune system mechanism for the balance between tolerance and immunity.  This gene encodes indoleamine 2, 3-dioxygenase (IDO) – a heme enzyme (EC=1.13.11.52) that catalyzes the first rate-limiting step in tryptophan catabolism to N-formyl-kynurenine and acts on multiple tryptophan substrates including D-tryptophan, L-tryptophan, 5-hydroxy-tryptophan, tryptamine, and serotonin.

The basic genetic information describes indoleamine 2, 3-dioxygenase 1 (IDO1, IDO, INDO) as an enzyme located at Chromosome 8p12-p11 (5; 6) that active at the first step of the Tryptophan catabolism.    The cloned gene structure showed that IDO contains 10 exons ad 9 introns (7; 8) producing 9 transcripts.

After alternative splicing only five of the transcripts encode a protein but the other four does not make protein products, three of transcripts retain intron and one of them create a nonsense code (7).  Based on IDO related studies 15 phenotypes of IDO is identified, of which, twelve in cancer tumor models of lung, kidney, endometrium, intestine, two in nervous system, and one HGMD- deletion.

  1. 2.     Location, Location and Location

The specific cellular location of IDO is in cytosol, smooth muscle contractile fibers and stereocilium bundle. The expression specificity shows that IDO is present very widely in all cell types but there is an elevation of expression in placenta, pancreas, pancreas islets, including dendritic cells (DCs) according to gene atlas of transcriptome (9).  Expression of IDO is common in antigen presenting cells (APCs), monocytes (MO), macrophages (MQs), DCs, T-cells, and some B-cells. IDO present in APCs (10; 11), due to magnitude of role play hierarchy and level of expression DCs are the better choice but including MOs during establishment of three DC cell subset, CD14+CD25+, CD14++CD25+ and CD14+CD25++ may increase the longevity and efficacy of the interventions.

IDO is strictly regulated and confined to immune system with diverse functions based on either positive or negative stimulations. The positive stimulations are T cell tolerance induction, apoptotic process, and chronic inflammatory response, type 2 immune response, interleukin-12 production (12).  The negative stimulations are interleukin-10 production, activated T cell proliferation, T cell apoptotic process.  Furthermore, there are more functions allocating fetus during female pregnancy; changing behavior, responding to lipopolysaccharide or multicellular organismal response to stress possible due to degradation of tryptophan, kynurenic acid biosynthetic process, cellular nitrogen compound metabolic process, small molecule metabolic process, producing kynurenine process (13; 14; 15).

IDO plays a role in a variety of pathophysiological processes such as antimicrobial and antitumor defense, neuropathology, immunoregulation, and antioxidant activity (16; 17; 18; 19).

 

 3.     Molecular Genetics of IDO:

A: Structure of human IDO2 gene and transcripts. Complete coding region is 1260 bps encoding a 420 aa polypeptide. Alternate splice isoforms lacking the exons indicated are noted. Hatch boxes represent a frameshift in the coding region to an alternate reading frame leading to termination. Black boxes represent 3' untranslated regions. Nucleotide numbers, intron sizes, and positioning are based on IDO sequence files NW_923907.1 and GI:89028628 in the Genbank database. (reference: http://atlasgeneticsoncology.org/Genes/IDO2ID44387ch8p11.html)

A: Structure of human IDO2 gene and transcripts. Complete coding region is 1260 bps encoding a 420 aa polypeptide. Alternate splice isoforms lacking the exons indicated are noted. Hatch boxes represent a frameshift in the coding region to an alternate reading frame leading to termination. Black boxes represent 3′ untranslated regions. Nucleotide numbers, intron sizes, and positioning are based on IDO sequence files NW_923907.1 and GI:89028628 in the Genbank database.
(reference: http://atlasgeneticsoncology.org/Genes/IDO2ID44387ch8p11.html)

Molecular genetics data from earlier findings based on reporter assay results showed that IDO promoter is regulated by ISRE-like elements and GAS-sequence at -1126 and -1083 region (20).  Two cis-acting elements are ISRE1 (interferon sequence response element 1) and interferon sequence response element 2 (ISRE2).

Analyses of site directed and deletion mutation with transfected cells demonstrated that introduction of point mutations at these elements decreases the IDO expression. Removing ISRE1 decreases the effects of IFNgamma induction 50 fold and deleting ISRE1 at -1126 reduced by 25 fold (3). Introducing point mutations in conserved t residues at -1124 and -1122 (from T to C or G) in ISRE consensus sequence NAGtttCA/tntttNCC of IFNa/b inducible gene ISG4 eliminates the promoter activity by 24 fold (21).

ISRE2 have two boxes, X box (-114/1104) and Y Box 9-144/-135), which are essential part of the IFNgamma response region of major histocompatibility complex class II promoters (22; 23).  When these were removed from ISRE2 or introducing point mutations at two A residues of ISRE2 at -111 showed a sharp decrease after IFNgamma treatment by 4 fold (3).

The lack of responses related to truncated or deleted IRF-1 interactions whereas IRF-2, Jak2 and STAT91 levels were similar in the cells, HEPg2 and ME180 (3). Furthermore, 748 bp deleted between these elements did not affect the IDO expression, thus the distance between ISRE1 and ISRE2 elements have no function or influence on IDO (3; 24)

B: Amino acid alignment of IDO and IDO2. Amino acids determined by mutagenesis and the crystal structure of IDO that are critical for catalytic activity are positioned below the human IDO sequence. Two commonly occurring SNPs identified in the coding region of human IDO2 are shown above the sequence which alter a critical amino acid (R248W) or introduce a premature termination codon (Y359stop).

B: Amino acid alignment of IDO and IDO2. Amino acids determined by mutagenesis and the crystal structure of IDO that are critical for catalytic activity are positioned below the human IDO sequence. Two commonly occurring SNPs identified in the coding region of human IDO2 are shown above the sequence which alter a critical amino acid (R248W) or introduce a premature termination codon (Y359stop).

4.     There are three types of IDO in human genome:

IDO was originally discovered in 1967 in rabbit intestine (25). Later, in 1990 the human IDO gene is cloned and sequenced (7).  However, its importance and relevance in immunology was not created until prevention of allocation of fetal rejection and founding expression in wide range of human cancers (26; 27).

There are three types of IDO, pro-IDO like, IDO1, and IDO2.  In addition, another enzyme called TDO, tryptophan 2, 3, dehydrogenase solely degrade L-Trp at first-rate limiting mechanism in liver and brain.

4.1.  IDO1:

IDO1 mechanism is the target for immunotherapy applications. The initial discovery of IDO in human physiology is protection of pregnancy (1) since lack of IDO results in premature recurrent abortion (28; 26; 29).   The initial rate-limiting step of tryptophan metabolism is catalyzed by either IDO or tryptophan 2, 3-dioxygenase (TDO).

Structural studies of IDO versus TDO presenting active site environments, conserved Arg 117 and Tyr113, found both in TDO and IDO for the Tyr-Glu motif, but His55 in TDO replaced by Ser167b in IDO (30; 2). As a result, they are regulated with different mechanisms (1; 2) (30).  The short-lived TDO, about 2h, responds to level of tryptophan and its expression regulated by glucorticoids (31; 32).  Thus, it is a useful target for regulation and induced by tryptophan so that increasing tryptophan induces NAD biosynthesis. Whereas, IDO is not activated by the level of Trp presence but inflammatory agents with its interferon stimulated response elements (ISRE1 and ISRE2) in its (33; 34; 35; 36; 3; 10) promoter.

TDO promoter contains glucorticoid response elements (37; 38) and regulated by glucocorticoids and other available amino acids for gluconeogenesis. This is how IDO binds to only immune response cells and TDO relates to NAD biosynthesis mechanisms. Furthermore, TDO is express solely in liver and brain (36).  NAD synthesis (39) showed increased IDO ubiquitous and TDO in liver and causing NAD level increase in rat with neuronal degeneration (40; 41).  NAM has protective function in beta-cells could be used to cure Type1 diabetes (40; 42; 43). In addition, knowledge on NADH/NAD, Kyn/Trp or Trp/Kyn ratios as well as Th1/Th2, CD4/CD8 or Th17/Threg are equally important (44; 40).

Active site of IDO–PI complex. (A) Stereoview of the residues around the heme of IDO viewed from the side of heme plane. The proximal ligand H346 is H-bonded to wa1. The 6-propionate of the heme contacts with wa2 and R343 Nε. The wa2 is H-bonded to wa1, L388 O, and 6-propionate. Mutations of F226, F227, and R231 do not lose the substrate affinity but produce the inactive enzyme. Two CHES molecules are bound in the distal pocket. The cyclohexan ring of CHES-1 (green) contacts with F226 and R231. The 7-propionate of the heme interacts with the amino group of CHES-1 and side chain of Ser-263. The mutational analyses for these distal residues are shown in Table 1. (B) Top view of A by a rotation of 90°. The proximal residues are omitted. (http://www.pnas.org/content/103/8/2611/F3.expansion.html)

Active site of IDO–PI complex. (A) Stereoview of the residues around the heme of IDO viewed from the side of heme plane. The proximal ligand H346 is H-bonded to wa1. The 6-propionate of the heme contacts with wa2 and R343 Nε. The wa2 is H-bonded to wa1, L388 O, and 6-propionate. Mutations of F226, F227, and R231 do not lose the substrate affinity but produce the inactive enzyme. Two CHES molecules are bound in the distal pocket. The cyclohexan ring of CHES-1 (green) contacts with F226 and R231. The 7-propionate of the heme interacts with the amino group of CHES-1 and side chain of Ser-263. The mutational analyses for these distal residues are shown in Table 1. (B) Top view of A by a rotation of 90°. The proximal residues are omitted. (http://www.pnas.org/content/103/8/2611/F3.expansion.html)

4.2. IDO2:

The third type of IDO, called IDO2 exists in lower vertebrates like chicken, fish and frogs (45) and in human with differential expression properties. The expression of IDO2 is only in DCs, unlike IDO1 expresses on both tumors and DCs in human tissues.  Yet, in lower invertebrates IDO2 is not inhibited by general inhibitor of IDO, D-1-methyl-tryptophan (1MT) (46).   Recently, two structurally unusual natural inhibitors of IDO molecules, EXIGUAMINES A and B, are synthesized (47).  LIP mechanism cannot be switch back to activation after its induction in IDO2 (46).

Crucial cancer progression can continue with production of IL6, IL10 and TGF-beta1 to help invasion and metastasis.  Inclusion of two common SNPs affects the function of IDO2 in certain populations.  SNP1 reduces 90% of IDO2 catalytic activity in 50% of European and Asian descent and SNP2 produce premature protein through inclusion of stop-codon in 25% of African descent lack functional IDO2 (Uniport).

4.3. IDO-like proteins: The Origin of IDO:

Knowing the evolutionary steps will helps us to identify how we can manage the regulator function to protect human health in cancer, immune disorders, diabetes, and infectious diseases.

Bacterial IDO has two types of IDOs that are group I and group II IDO (48).  These are the earliest version of the IDO, pro-IDO like, proteins with a quite complicated function.  Each microorganism recognized by a specific set of receptors, called Toll-Like Receptors (TLR), to activate the IDO-like protein expression based on the origin of the bacteria or virus (49; 35).   Thus, the genesis of human IDO originates from gene duplication of these early bacterial versions of IDO-like proteins after their invasion interactions with human host.  IDO1 only exists in mammals and fungi.

Fungi also has three types of IDO; IDOa, IDO beta, and IDO gamma (50) with different properties than human IDOs, perhaps multiple IDO is necessary for the world’s decomposers.

All globins, haemoglobins and myoglobins are destined to evolve from a common ancestor, which  is only 14-16kDa (51) length. Binding of a heme and being oxygen carrier are central to the enzyme mechanism of this family.  Globins are classified under three distinct origins; a universal globin, a compact globin, and IDO-like globin (52) IDO like globin widely distributed among gastropodic mollusks (53; 51).  The indoleamine 2, 3-dioxygenase 1–like “myoglobin” (Myb) was discovered in 1989 in the buccal mass of the abalone Sulculus diversicolor (54).

The conserved region between Myb and IDO-like Myb existed for at least 600 million years (53) Even though the splice junction of seven introns was kept intact, the overall homolog region between Myb and IDO is only about 35%.

No significant evolutionary relationship is found between them after their amino acid sequence of each exon is compared to usual globin sequences. This led the hint that molluscan IDO-like protein must have other functions besides carrying oxygen, like myoglobin.   Alignment of S. cerevisiae cDNA, mollusk and vertebrate IDO–like globins show the key regions for controlling IDO or myoglobin function (55). These data suggest that there is an alternative pathways of myoglobin evolution.  In addition, understanding the diversity of globin may help to design better protocols for interventions of diseases.

Mechanisms of IDO:

The dichotomy of IDO mechanism lead the discovery that IDO is more than an enzyme as a versatile regulator of innate and adaptive immune responses in DCs (66; 67; 68). Meantime IDO also involve with Th2 response and B cell mediated autoimmunity showing that it has three paths, short term (acute) based on enzymatic actions, long term (chronic) based on non-enzymatic role, and moonlighting relies of downstream metabolites of tryptophan metabolism (69; 70).

IFNgamma produced by DC, MQ, NK, NKT, CD4+ T cells and CD8+ T cells, after stimulation with IL12 and IL8.  Inflammatory cytokine(s) expressed by DCs produce IFNgamma to stimulate IDO’s enzymatic reactions in acute response.  Then, TDO in liver and tryptophan catabolites act through Aryl hydrocarbon receptor induction for prevention of T cell proliferation. This mechanism is common among IDO, IDO2 (expresses in brain and liver) and TDO expresses in liver) provide an acute response for an innate immunity (30). When the pDCs are stimulated with IFNgamma, activation of IDO is go through Jak, STAT signaling pathway to degrade Trp to Kyn causing Trp depletion. The starvation of tryptophan in microenvironment inhibits generation of T cells by un-read t-RNAs and induce apoptosis through myc pathway.  In sum, lack of tryptophan halts T cell proliferation and put the T cells in apoptosis at S1 phase of cell division (71; 62).

The intermediary enzymes, functioning during Tryptophan degradation in Kynurenine (Kyn) pathway like kynurenine 3-hydroxylase and kynureninase, are also induced after stimulation with liposaccaride and proinflammatory cytokines (72). They exhibit their function in homeostasis through aryl-hydrocarbon receptor (AhR) induction by kynurenine as an endogenous signal (73; 74).  The endogenous tumor-promoting ligand of AhR are usually activated by environmental stress or xenobiotic toxic chemicals in several cellular processes like tumorigenesis, inflammation, transformation, and embryogenesis (Opitz ET. Al, 2011).

Human tumor cells constitutively produce TDO also contributes to production of Kyn as an endogenous ligand of the AhR (75; 27).  Degradation of tryptophan by IDO1/2 in tumors and tumor-draining lymph nodes occur. As a result, there are animal studies and Phase I/II clinical trials to inhibit the IDO1/2 to prevent cancer and poor prognosis (NewLink Genetics Corp. NCT00739609, 2007).

 IDO mechanism for immune response

Systemic inflammation (like in sepsis, cerebral malaria and brain tumor) creates hypotension and IDO expression has the central role on vascular tone control (63).  Moreover, inflammation activates the endothelial coagulation activation system causing coagulopathies on patients.  This reaction is namely endothelial cell activation of IDO by IFNgamma inducing Trp to Kyn conversion. After infection with malaria the blood vessel tone has decreases, inflammation induce IDO expression in endothelial cells producing Kyn causing decreased trp, lower arterial relaxation, and develop hypotension (Wang, Y. et. al 2010).  Furthermore, existing hypotension in knock out Ido mice point out a secondary mechanism driven by Kyn as an endogenous ligand to activate non-canonical NfKB pathway (63).

Another study also hints this “back –up” mechanism by a significant outcome with a differential response in pDCs against IMT treatment.  Unlike IFN gamma conditioned pDC blocks T cell proliferation and apoptosis, methyl tryptophan fails to inhibit IDO activity for activating naïve T cells to make Tregs at TGF-b1 conditioned pDCs (77; 78).

 Indoleamine-Pyrrole 2,3,-Dioxygenase; IDO dioxygenase; Indeolamine-2,3

The second role of the IDO relies on non-enzymatic action as being a signal molecule. Yet, IDO2 and TDO are devoid of this function. This role mainly for maintenance of microenvironment condition. DCs response to TGFbeta-1 exposure starts the kinase Fyn induce phosphorylation of IDO-associated immunoreceptor tyrosine–based inhibitory motifs (ITIMs) for propagation of the downstream signals involving non-canonical (anti-inflammatory) NF-kB pathway for a long term response. When the pDCs are conditioned with TGF-beta1 the signaling (68; 77; 78) Phospho Inositol Kinase3 (PIK-3)-dependent and Smad independent pathways (79; 80; 81; 82; 83) induce Fyn-dependent phosphorylation of IDO ITIMs.  A prototypic ITIM has the I/V/L/SxYxxL/V/F sequence (84), where x in place of an amino acid and Y is phosphorylation sites of tyrosines (85; 86).

Smad independent pathway stimulates SHP and PIK3 induce both SHP and IDO phosphorylation. Then, formed SHP-IDO complex can induce non-canonical (non-inflammatory) NF-kB pathway (64; 79; 80; 82) by phosphorylation of kinase IKKa to induce nuclear translocation of p52-Relb towards their targets.  Furthermore, the SHP-IDO complex also may inhibit IRAK1 (68). SHP-IDO complex activates genes through Nf-KB for production of Ido1 and Tgfb1 genes and secretion of IFNalpha/IFNbeta.  IFNa/IFNb establishes a second short positive feedback loop towards p52-RelB for continuous gene expression of IDO, TGFb1, IFNa and IFNb (87; 68).  However, SHP-IDO inhibited IRAK1 also activates p52-RelB.  Nf-KB induction at three path, one main and two positive feedback loops, is also critical.  Finally, based on TGF-beta1 induction (76) cellular differentiation occurs to stimulate naïve CD4+ T cell differentiation to regulatory T cells (Tregs).  In sum, TGF-b1 and IFNalpha/IFNbeta stimulate pDCs to keep inducing naïve T cells for generation of Treg cells at various stages, initiate, maintain, differentiate, infect, amplify, during long-term immune responses (67; 66).

Moonlighting function of Kyn/AhR is an adaptation mechanism after the catalytic (enzymatic) role of IDO depletes tryptophan and produce high concentration of Kyn induce Treg and Tr1 cell expansion leading Tregs to use TGFbeta for maintaining this environment (67; 76). In this role, Kyn pathway has positive-feedback-loop function to induce IDO expression.

In T cells, tryptophan starvation induces Gcn2-dependent stress signaling pathway, which initiates uncharged Trp-tRNA binding onto ribosomes. Elevated GCN2 expression stimulates elF2alfa phosphorylation to stop translation initiation (88). Therefore, most genes downregulated and LIP, an alternatively initiated isoform of the b/ZIP transcription factor NF-IL6/CEBP-beta (89).

This mechanism happens in tumor cells based on Prendergast group observations. As a result, not only IDO1 propagates itself while producing IFNalpha/IFNbeta, but also demonstrates homeostasis choosing between immunegenity by production of TH17or tolerance by Tregs. This mechanism acts like a see-saw. Yet, tolerance also can be broken by IL6 induction so reversal mechanism by SOC-3 dependent proteosomal degradation of the enzyme (90).  All proper responses require functional peripheral DCs to generate mature DCs for T cells to avoid autoimmunity (91).

Niacin (vitamin B3) is the final product of tryptophan catabolism and first molecule at Nicotinomic acid (NDA) Biosynthesis.  The function of IDO in tryptophan and NDA metabolism has a great importance to develop new clinical applications (40; 42; 41).  NAD+, biosynthesis and tryptophan metabolisms regulate several steps that can be utilize pharmacologically for reformation of healthy physiology (40).

IDO for protection in Microbial Infection with Toll-like Receptors

The mechanism of microbial response and infectious tolerance are complex and the origination of IDO based on duplication of microbial IDO (49).  During microbial responses, Toll-like receptors (TLRs) play a role to differentiate and determine the microbial structures as a ligand to initiate production of cytokines and pro-inflammatory agents to activate specific T helper cells (92; 93; 94; 95). Uniqueness of TLR comes from four major characteristics of each individual TLR by ligand specificity, signal transduction pathways, expression profiles and cellular localization (96). Thus, TLRs are important part of the immune response signaling mechanism to initiate and design adoptive responses from innate (naïve) immune system to defend the host.

TLRs are expressed cell type specific patterns and present themselves on APCs (DCs, MQs, monocytes) with a rich expression levels (96; 97; 98; 99; 93; 100; 101; 102; 87). Induction signals originate from microbial stimuli for the genesis of mature immune response cells.  Co-stimulation mechanisms stimulate immature DCs to travel from lymphoid organs to blood stream for proliferation of specific T cells (96).  After the induction of iDCs by microbial stimuli, they produce proinflammatory cytokines such as TNF and IL-12, which can activate differentiation of T cells into T helper cell, type one (Th1) cells. (103).

Utilizing specific TLR stimulation to link between innate and acquired responses can be possible through simple recognition of pathogen-associated molecular patterns (PAMPs) or co-stimulation of PAMPs with other TLR or non-TLR receptors, or even better with proinflammatory cytokines.   Some examples of ligand- TLR specificity shown in Table1, which are bacterial lipopeptides, Pam3Cys through TLR2 (92; 104; 105).  Double stranded (ds) RNAs through TLR3 (106; 107), Lipopolysaccharide (LPS) through TLR4, bacterial flagellin through TLR5 (108; 109), single stranded RNAs through TLR7/8 (97; 98), synthetic anti-viral compounds imiquinod through TLR 7 and resiquimod through TLR8, unmethylated CpG DNA motifs through TLR9 (Krieg, 2000).

IDO action

Then, the specificity is established by correct pairing of a TLR with its proinflammatory cytokines, so that these permutations influence creation and maintenance of cell differentiation. For example, leading the T cell response toward a preferred Th1 or Th2 response possible if the cytokines TLR-2 mediated signals induce a Th2 profile when combined with IL-2 but TLR4 mediated signals lean towards Th1 if it is combined with IL-10 or Il-12, (110; 111)  (112).

TLR ligand TLR Reference
Lipopolysaccharide, LPS TLR4 (96).  (112).
Lipopeptides, Pam3Cys TLR2 (92; 104; 105)
Double stranded (ds) RNAs TLR3 (106; 107)
Bacterial flagellin TLR5 (108; 109)
Single stranded RNAs TLR7/8 (97; 98)
Unmethylated CpG DNA motifs TLR9 (Krieg, 2000)
Synthetic anti-viral compounds imiquinod and resiquimod TLR7 and TLR8 (Lee J, 2003)

Furthermore, if the DCs are stimulated with IL-6, DCs relieve the suppression of effector T cells by regulatory T cells (113).

The modification of IDO+ monocytes manage towards specific subset of T cell activation with specific TLRs are significantly important (94).

The type of cell with correct TLR and stimuli improves or decreases the effectiveness of stimuli. Induction of IDO in monocytes by synthetic viral RNAs (isRNA) and CMV was possible, but not in monocyte derived DCs or TLR2 ligand lipopeptide Pam3Cys since single- stranded RNA ligands target TLR7/8 in monocytes derive DCs only (Lee J, 2003).  These data show that TLRs has ligand specificity, signal transduction pathways, expression profiles and cellular localization so design of experiments should follow these rules.

Conclusion:

Overall our purpose of this information is to find a method to manipulate IDO to correct/fix/modulate immune responses for clinical applications.  This first part of the review concerns the basic science information gained overall several years that lay the foundation that translational research scientist should familiar to develop a new technology for clinic. The first connection of IDO and human health came from a very natural event that is protection of pregnancy in human. The focus of the translational medicine is treatment of cancer or prevention/delay cancer by stem cell based Dendritic Cell Vaccine (DCvax) development.

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Calcium Cycling (ATPase Pump) in Cardiac Gene Therapy: Inhalable Gene Therapy for Pulmonary Arterial Hypertension and Percutaneous Intra-coronary Artery Infusion for Heart Failure: Contributions by Roger J. Hajjar, MD

Calcium Cycling (ATPase Pump) in Cardiac Gene Therapy: Inhalable Gene Therapy for Pulmonary Arterial Hypertension and Percutaneous Intra-coronary Artery Infusion for Heart Failure: Contributions by Roger J. Hajjar, MD

Curator: Aviva Lev-Ari, PhD, RN

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Article VI Calcium Cycling (ATPase Pump) in Cardiac Gene Therapy Inhalable Gene Therapy for Pulmonary Arterial Hypertension and Percutaneous Intra-coronary Artery Infusion for Heart

Image created by Adina Hazan 06/30/2021

This article is Part VI in a Series of articles on Calcium Release Mechanism, the series consists of the following articles:

Part I: Identification of Biomarkers that are Related to the Actin Cytoskeleton

Larry H Bernstein, MD, FCAP

http://pharmaceuticalintelligence.com/2012/12/10/identification-of-biomarkers-that-are-related-to-the-actin-cytoskeleton/

Part II: Role of Calcium, the Actin Skeleton, and Lipid Structures in Signaling and Cell Motility

Larry H. Bernstein, MD, FCAP, Stephen Williams, PhD and Aviva Lev-Ari, PhD, RN

http://pharmaceuticalintelligence.com/2013/08/26/role-of-calcium-the-actin-skeleton-and-lipid-structures-in-signaling-and-cell-motility/

Part III: Renal Distal Tubular Ca2+ Exchange Mechanism in Health and Disease

Larry H. Bernstein, MD, FCAP, Stephen J. Williams, PhD
 and Aviva Lev-Ari, PhD, RN

http://pharmaceuticalintelligence.com/2013/09/02/renal-distal-tubular-ca2-exchange-mechanism-in-health-and-disease/

Part IV: The Centrality of Ca(2+) Signaling and Cytoskeleton Involving Calmodulin Kinases and Ryanodine Receptors in Cardiac Failure, Arterial Smooth Muscle, Post-ischemic Arrhythmia, Similarities and Differences, and Pharmaceutical Targets

Larry H Bernstein, MD, FCAP, Justin Pearlman, MD, PhD, FACC and Aviva Lev-Ari, PhD, RN

http://pharmaceuticalintelligence.com/2013/09/08/the-centrality-of-ca2-signaling-and-cytoskeleton-involving-calmodulin-kinases-and-ryanodine-receptors-in-cardiac-failure-arterial-smooth-muscle-post-ischemic-arrhythmia-similarities-and-differen/

Part V: Ca2+-Stimulated Exocytosis:  The Role of Calmodulin and Protein Kinase C in Ca2+ Regulation of Hormone and Neurotransmitter

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

http://pharmaceuticalintelligence.com/2013/12/23/calmodulin-and-protein-kinase-c-drive-the-ca2-regulation-of-hormone-and-neurotransmitter-release-that-triggers-ca2-stimulated-exocytosis/

Part VI: Calcium Cycling (ATPase Pump) in Cardiac Gene Therapy: Inhalable Gene Therapy for Pulmonary Arterial Hypertension and Percutaneous Intra-coronary Artery Infusion for Heart Failure: Contributions by Roger J. Hajjar, MD

Aviva Lev-Ari, PhD, RN

http://pharmaceuticalintelligence.com/2013/08/01/calcium-molecule-in-cardiac-gene-therapy-inhalable-gene-therapy-for-pulmonary-arterial-hypertension-and-percutaneous-intra-coronary-artery-infusion-for-heart-failure-contributions-by-roger-j-hajjar/

Part VII: Cardiac Contractility & Myocardium Performance: Ventricular Arrhythmias and Non-ischemic Heart Failure – Therapeutic Implications for Cardiomyocyte Ryanopathy (Calcium Release-related Contractile Dysfunction) and Catecholamine Responses

Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

http://pharmaceuticalintelligence.com/2013/08/28/cardiac-contractility-myocardium-performance-ventricular-arrhythmias-and-non-ischemic-heart-failure-therapeutic-implications-for-cardiomyocyte-ryanopathy-calcium-release-related-contractile/

Part VIII: Disruption of Calcium Homeostasis: Cardiomyocytes and Vascular Smooth Muscle Cells: The Cardiac and Cardiovascular Calcium Signaling Mechanism

Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

http://pharmaceuticalintelligence.com/2013/09/12/disruption-of-calcium-homeostasis-cardiomyocytes-and-vascular-smooth-muscle-cells-the-cardiac-and-cardiovascular-calcium-signaling-mechanism/

Part IXCalcium-Channel Blockers, Calcium Release-related Contractile Dysfunction (Ryanopathy) and Calcium as Neurotransmitter Sensor

Justin Pearlman, MD, PhD, FACC, Larry H Bernstein, MD, FCAP and Aviva Lev-Ari, PhD, RN

Part X: Synaptotagmin functions as a Calcium Sensor: How Calcium Ions Regulate the fusion of vesicles with cell membranes during Neurotransmission

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

http://pharmaceuticalintelligence.com/2013/09/10/synaptotagmin-functions-as-a-calcium-sensor-how-calcium-ions-regulate-the-fusion-of-vesicles-with-cell-membranes-during-neurotransmission/

Part XI: Sensors and Signaling in Oxidative Stress

Larry H. Bernstein, MD, FCAP

http://pharmaceuticalintelligence.com/2013/11/01/sensors-and-signaling-in-oxidative-stress/

Part XII: Atherosclerosis Independence: Genetic Polymorphisms of Ion Channels Role in the Pathogenesis of Coronary Microvascular Dysfunction and Myocardial Ischemia (Coronary Artery Disease (CAD))

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

http://pharmaceuticalintelligence.com/2013/12/21/genetic-polymorphisms-of-ion-channels-have-a-role-in-the-pathogenesis-of-coronary-microvascular-dysfunction-and-ischemic-heart-disease/

This article has THREE parts:

Part I: Scientific Leader in Cardiology, Contributions by Roger J. Hajjar, MD to Gene Therapy

Part II: Cardiac Gene Therapy: Inhalable Gene Therapy for Pulmonary Arterial Hypertension

Part III: Cardiac Gene Therapy: Percutaneous Intra-coronary Artery Infusion for Heart Failure

The following two discoveries in Cardiac Gene Therapies represent the FRONTIER IN CARDIOLOGY for 2012 – 2013: Solution Advancement for Improving Myocardial Contractility

Part I: Scientific Leader in Cardiology, Contributions by Roger J. Hajjar, MD to Gene Therapy

Roger J. Hajjar, MD, a pioneering Mount Sinai researcher who has published cutting-edge studies on heart failure, has been named the recipient of the 2013 BCVS Distinguished Achievement Award by theAmerican Heart Association and the Council on Basic Cardiovascular Sciences. Dr. Hajjar, who is The Arthur and Janet C. Ross Professor of Medicine and Director of The Helmsley Trust Translational Research Center, will be honored at the American Heart Association’s Scientific Sessions Annual Conference later this year.

“Dr. Hajjar will receive the award for his groundbreaking contributions to developing gene therapy treatments for cardiac disease,” says Joshua Hare, MD, who is President-elect of the Council on Basic Cardiovascular Sciences. He will also be recognized for his work on behalf of the Council.

Over the years, Dr. Hajjar’s laboratory has made important basic science discoveries that were translated into clinical trials. Most recently, Dr. Hajjar and his researchers identified a possible new drug target for treating or preventing heart failure. Says Mark A. Sussman, PhD, a former president of the Council, “Dr. Hajjar was among the first, and certainly the most successful, in combining gene therapy and treatment of heart failure. He shows a relentless pursuit of translating basic science into real-world treatment of heart disease.”

This article was first published in Inside Mount Sinai.

http://blog.mountsinai.org/blog/roger-j-hajjar-md-to-be-honored-for-research/

John Hopkins, Distinguished Alumnus Award 2011

Roger J. Hajjar, Engr ’86
Dr. Roger Hajjar received his bachelor’s degree in biomedical engineering from Johns Hopkins University in 1986. A cardiologist and translational scientist, he is a leader in gene therapy techniques and model testing for cardiovascular diseases. Dr. Hajjar is professor of medicine and cardiology, and professor of gene and cell medicine at Mount Sinai Medical Center in New York, as well as research director of Mount Sinai’s Wiener Family Cardiovascular Research Laboratories. Dr. Hajjar was recruited to Mt. Sinai from Harvard Medical School where he was assistant professor of medicine and staff cardiologist in the Heart Failure & Cardiac Transplantation Center. He received his medical degree from Harvard Medical School and trained in internal medicine and cardiology at Massachusetts General Hospital in Boston. Dr. Hajjar has concentrated his research efforts on understanding the basic mechanisms of heart failure. He has developed gene transfer methods and techniques in the heart to improve contractility. Dr. Hajjar’s laboratory focuses on targeting signaling pathways in cardiac myocytes to improve contractile function in heart failure and to block signaling pathways in hypertrophy and apoptosis. Dr. Hajjar has significant expertise in gene therapy. In 1996, he won the Young Investigator Award of the American Heart Association (Council on Circulation). In 1999, Dr. Hajjar was awarded the prestigious Doris Duke Clinical Scientist award and won first prize at the Astra Zeneca Young Investigator Forum. Dr. Hajjar holds a number of NIH grants.

http://alumni.jhu.edu/distinguishedalumni2011

Dr Hajjar is the Director of the Cardiovascular Research Center, and the Arthur & Janet C. Ross Professor of Medicine at Mount Sinai School of Medicine, New York, NY. He received his BS in Biomedical Engineering from Johns Hopkins University and his MD from Harvard Medical School and the Harvard-MIT Division of Health Sciences & Technology. He completed his training in internal medicine, cardiology and research fellowships at Massachusetts General Hospital in Boston.

Dr. Hajjar is an internationally renowned scientific leader in the field of cardiac gene therapy for heart failure. His laboratory focuses on molecular mechanisms of heart failure and has validated the cardiac sarcoplasmic reticulum calcium ATPase pump, SERCA2a, as a target in heart failure, developed methodologies for cardiac directed gene transfer that are currently used by investigators throughout the world, and examined the functional consequences of SERCA2a gene transfer in failing hearts. His basic science laboratory remains one of the preeminent laboratories for the investigation of calcium cycling in failing hearts and targeted gene transfer in various animal models. The significance of Dr Hajjar’s research has been recognized with the initiation and recent successful completion of phase 1 and phase 2 First-in-Man clinical trials of SERCA2a gene transfer in patients with advanced heart failure under his guidance.

Prior to joining Mount Sinai, Dr. Hajjar served as Director of the Cardiovascular Laboratory of Integrative Physiology and Imaging at Massachusetts General Hospital and Associate Professor of Medicine at Harvard Medical School. Dr. Hajjar has also been a staff cardiologist in the Heart Failure & Cardiac Transplantation Center at Massachusetts General Hospital.

Dr. Hajjar has won numerous awards and distinctions, including the Young Investigator Award of the American Heart Association. He was awarded a Doris Duke Clinical Scientist award and has won first prize at the Astra Zeneca Young Investigator Forum. He is a member of the American Society for Clinical Investigation. He was recently awarded the Distinguished Alumnus Award from Johns Hopkins University and the Mount Sinai Dean’s award for Excellence in Translational Science. He has authored over 260 peer-reviewed publications.

http://heart.sdsu.edu/~website/IRRI/Pages/faculty/roger-hajjar-md.html

Meet the Director of Mount Sinai’s Cardiovascular Research Center

“Cardiovascular diseases are the number one cause of death globally. In order to tackle them in all aspects, we must unite improved diagnostic techniques with more refined therapies.”

Roger J. Hajjar, MD, Director of the Cardiovascular Research Center, the Arthur & Janet C. Ross Professor of Medicine, Professor of Gene & Cell Medicine, Director of the Cardiology Fellowship Program, and Co-Director of the Transatlantic Cardiovascular Research Center, which combines Mount Sinai Cardiology Laboratories with those of the Universite de Paris – Madame Curie.

In the late 1990s, the possibility that discoveries in genetics and genomics could have a positive impact on the diagnosis, treatment, and prevention of cardiovascular diseases seemed to be just a distant promise. Today, a little more than a decade later, the promise is beginning to take shape. Roger J. Hajjar, MD and his multidisciplinary team of investigators are beginning to translate scientific findings into real therapies for cardiovascular diseases. As Director of the Cardiovascular Research Institute and a cardiologist by training, Dr. Hajjar guides the growth of a cutting-edge translational research laboratory, which is positioning Mount Sinai as the leader in cardiovascular genomics.

An internationally recognized scientific leader in the field of cardiac gene therapy for heart failure, Dr. Hajjar is expanding studies of the basic mechanisms of cardiac diseases and identification of high-risk groups and genomic predictors so that they can be part of the daily clinical care of patients. Unique biorepositories combined with cardiovascular areas of excellence across Mount Sinai make possible crucial genetic studies.

First Gene Therapy for Heart Failure

Under Dr. Hajjar’s leadership, the Cardiovascular Research Center has already developed the world’s first potential gene therapy for heart failure. Known as AAV1.SERCA2a, this therapy actually revives heart tissue that has stopped working properly. It has led to new treatment possibilities for patients with advanced heart failure, whose options used to be severely limited. The significance of this research has been recognized with the initiation and successful completion Phase 1 and Phase 2 First-in-Man clinical trials of SERCA2a gene transfer in patients with advanced heart failure. Phase 3 validation begins in 2011.

The Cardiovascular Research Center’s next research projects, already underway, focus on using novel gene therapy vectors to target diastolic heart failure, ventricular arrhythmias, pulmonary hypertension, and myocardial infarctions.

In addition to targeting signaling pathways to aid failing heart cells, ongoing work at the Cardiovascular Research Center involves studying how to block signaling pathways in cardiac hypertrophy as well as apoptosis. The laboratory team is also targeting a number of signaling pathways in the aging heart to improve dystolic function.

Prior to joining Mount Sinai in 2007, Dr. Hajjar served as Director of the Cardiovascular Laboratory of Integrative Physiology and Imaging at Massachusetts General Hospital and Associate Professor of Medicine at Harvard Medical School. Dr. Hajjar has also been a staff cardiologist in the Heart Failure & Cardiac Transplantation Center at Massachusetts General Hospital. After earning a bachelors of science degree in Biomedical Engineering from Johns Hopkins University and a medical degree from Harvard Medical School and the Harvard-MIT Division of Health Sciences and Technology, he completed his training in internal medicine, cardiology and research fellowships at Massachusetts General Hospital in Boston.

Scientific Advisors

Roger J. Hajjar, MD, Co-Founder and a Scientific Advisor of Celladon Co, plans to commercialize AAV1.SERCA2a for the treatment of heart failure.
Dr. Roger J. Hajjar is the Director of the Cardiovascular Research Center at the Mt. Sinai School of Medicine. Previously, he was the Director of the Cardiovascular Laboratory of Integrative Physiology and Imaging at Massachusetts General Hospital (MGH) and Associate Professor of Medicine at Harvard Medical School. Dr. Hajjar has an active basic science laboratory and concentrates his research efforts on understanding the basic mechanisms of heart failure. He has developed gene transfer methods and techniques targeting the heart as a therapeutic modality to improve contractility in heart failure. Dr. Hajjar’s laboratory focuses on targeting signaling pathways in cardiac myocytes to improve contractile function in heart failure and to block signaling pathways in hypertrophy and apoptosis.

Gene Therapy: Volume 19, Issue 6 (June 2012)

Special Issue: Cardiovascular Gene Therapy

Guest Editor

Roger J Hajjar MD, Mount Sinai School of Medicine, New York, NY Director, Cardiovascular Research Institute, Arthur & Janet C Ross Professor of Medicine

SDF-1 in myocardial repair  

M S Penn, J Pastore, T Miller and R Aras

Gene Ther 19: 583-587; doi:10.1038/gt.2012.32

Abstract | Full Text | PDF

Gene- and cell-based bio-artificial pacemaker: what basic and translational lessons have we learned?  

R A Li

Gene Ther 19: 588-595; doi:10.1038/gt.2012.33

Abstract | Full Text | PDF

Sarcoplasmic reticulum and calcium cycling targeting by gene therapy  

J-S Hulot, G Senyei and R J Hajjar

Gene Ther 19: 596-599; advance online publication, May 17, 2012; doi:10.1038/gt.2012.34

Abstract | Full Text | PDF

Gene therapy for ventricular tachyarrhythmias  

J K Donahue

Gene Ther 19: 600-605; advance online publication, April 26, 2012; doi:10.1038/gt.2012.35

Abstract | Full Text | PDF

Prospects for gene transfer for clinical heart failure  

T Tang, M H Gao and H Kirk Hammond

Gene Ther 19: 606-612; advance online publication, April 26, 2012; doi:10.1038/gt.2012.36

Abstract | Full Text | PDF

Targeting S100A1 in heart failure  

J Ritterhoff and P Most

Gene Ther 19: 613-621; advance online publication, February 16, 2012; doi:10.1038/gt.2012.8

Abstract | Full Text | PDF

VEGF gene therapy: therapeutic angiogenesis in the clinic and beyond  

M Giacca and S Zacchigna

Gene Ther 19: 622-629; advance online publication, March 1, 2012; doi:10.1038/gt.2012.17

Abstract | Full Text | PDF

Vein graft failure: current clinical practice and potential for gene therapeutics  

S Wan, S J George, C Berry and A H Baker

Gene Ther 19: 630-636; advance online publication, March 29, 2012; doi:10.1038/gt.2012.29

Abstract | Full Text | PDF

Percutaneous methods of vector delivery in preclinical models  

D Ladage, K Ishikawa, L Tilemann, J Müller-Ehmsen and Y Kawase

Gene Ther 19: 637-641; advance online publication, March 15, 2012; doi:10.1038/gt.2012.14

Abstract | Full Text | PDF

Lentiviral vectors and cardiovascular diseases: a genetic tool for manipulating cardiomyocyte differentiation and function  

E Di Pasquale, M V G Latronico, G S Jotti and G Condorelli

Gene Ther 19: 642-648; advance online publication, March 1, 2012; doi:10.1038/gt.2012.19

Abstract | Full Text | PDF

Intracellular transport of recombinant adeno-associated virus vectors  

M Nonnenmacher and T Weber

Gene Ther 19: 649-658; advance online publication, February 23, 2012; doi:10.1038/gt.2012.6

Abstract | Full Text | PDF

Gene delivery technologies for cardiac applications  

M G Katz, A S Fargnoli, L A Pritchette and C R Bridges

Gene Ther 19: 659-669; advance online publication, March 15, 2012; doi:10.1038/gt.2012.11

Abstract | Full Text | PDF

Cardiac gene therapy in large animals: bridge from bench to bedside  

K Ishikawa, L Tilemann, D Ladage, J Aguero, L Leonardson, K Fish and Y Kawase

Gene Ther 19: 670-677; advance online publication, February 2, 2012; doi:10.1038/gt.2012.3

Abstract | Full Text | PDF

Progress in gene therapy of dystrophic heart disease  

Y Lai and D Duan

Gene Ther 19: 678-685; advance online publication, February 9, 2012; doi:10.1038/gt.2012.10

Abstract | Full Text | PDF

Targeting GRK2 by gene therapy for heart failure: benefits above β-blockade  

J Reinkober, H Tscheschner, S T Pleger, P Most, H A Katus, W J Koch and P W J Raake

Gene Ther 19: 686-693; advance online publication, February 16, 2012; doi:10.1038/gt.2012.9

Abstract | Full Text | PDF

Directed evolution of novel adeno-associated viruses for therapeutic gene delivery  

M A Bartel, J R Weinstein and D V Schaffer

Gene Ther 19: 694-700; advance online publication, March 8, 2012; doi:10.1038/gt.2012.20

Abstract | Full Text | PDF

http://www.nature.com/gt/journal/v19/n6/index.html

Part II: Cardiac Gene Therapy: Inhalable Gene Therapy for Pulmonary Arterial Hypertension

Public release date: 30-Jul-2013

Contact: Lauren Woods
lauren.woods@mountsinai.org
212-241-2836
The Mount Sinai Hospital / Mount Sinai School of Medicine

Inhalable gene therapy may help pulmonary arterial hypertension patients

Gene therapy when inhaled may restore function of a crucial enzyme in the lungs to reverse deadly PAH

The deadly condition known as pulmonary arterial hypertension (PAH), which afflicts up to 150,000 Americans each year, may be reversible by using an inhalable gene therapy, report an international team of researchers led by investigators at the Cardiovascular Research Center at Icahn School of Medicine at Mount Sinai.

In their new study, reported in the July 30 issue of the journal Circulation, scientists demonstrated that gene therapy administered through a nebulizer-like inhalation device can completely reverse PAH in rat models of the disease. In the lab, researchers also showed in pulmonary artery PAH patient tissue samples reduced expression of the SERCA2a, an enzyme critical for proper pumping of calcium in calcium compartments within the cells. SERCA2a gene therapy could be sought as a promising therapeutic intervention in PAH.

“The gene therapy could be delivered very easily to patients through simple inhalation — just like the way nebulizers work to treat asthma,” says study co-senior investigator Roger J. Hajjar, MD, Director of the Cardiovascular Research Center and the Arthur & Janet C. Ross Professor of Medicine and Professor of Gene & Cell at Icahn School of Medicine at Mount Sinai. “We are excited about testing this therapy in PAH patients who are in critical need of intervention.”

This same SERCA2a dysfunction also occurs in heart failure. This new study utilizes the same gene therapy currently being tested in patients to reverse congestive heart failure in a large phase III clinical trial in the United States and Europe.

“What we have shown is that gene therapy restores function of this crucial enzyme in diseased lungs,” says Dr. Hajjar. “We are delighted with these new findings because it suggests that a gene therapy that is already showing great benefit in congestive heart failure patients may be able to help PAH patients who currently have no good treatment options — and are in critical need of a life sustaining therapy.”

When SERCA2a is down-regulated, calcium stays longer in the cells than it should, and it induces pathways that lead to overgrowth of new and enlarged cells. According to researchers, the delivery of the SERCA2a gene produces SERCA2a enzymes, which helps both heart and lung cells restore their proper use of calcium.

“We are now on a path toward PAH patient clinical trials in the near future,” says Dr. Hajjar, who developed the gene therapy approach. Studies in large animal models are now underway. SERCA2a gene therapy has already been approved by the National Institutes of Health for human study.

A Simple Inhalation Corrects Deadly Dysfunction

PAH most commonly results from heart failure in the left side of the heart or from a pulmonary embolism, when clots in the legs travel to the lungs and cause blockages. When the lung is damaged from these conditions, the tissue starts to quickly produce new and enlarged cells, which narrows pulmonary arteries. This increases the pressure inside them. The high pressure in these arteries resists the heart’s effort to pump through them and the blood flow between the heart and lungs is reduced. The right side of the heart then must overcome the resistance and work harder to push the blood through the pulmonary arteries into the lungs. Over time, the right ventricle becomes thickened and enlarged and heart failure develops.

The gene therapy that Dr. Hajjar developed uses a modified adeno-associated viral-vector that is derived from a parvovirus. It works by introducing a healthy SERCA2a gene into cells, but this gene does not incorporate into a patient’s chromosome, according to the study’s lead author, Lahouaria Hadri, PhD, an Instructor of Medicine in Cardiology at Icahn School of Medicine at Mount Sinai.

“The clinical trials in congestive heart failure have shown already that the gene therapy is very safe,” says Dr. Hadri. Between 40-50 percent of individuals have antecedent antibodies to the adeno-associated vectors, so potential patients need to be screened before gene therapy to make sure they are eligible to receive the vectors. In patients without antibodies, the restorative enzyme gene therapy does not cause an immune response, according to Dr. Hadri.

The clinical application of the gene therapy for patients with PAH will most likely differ from those with heart failure. The replacement gene needs to be injected through the coronary arteries of heart failure patients using catheters, while in PAH patients, the gene will need to be administered through inhalation.

This study was supported by National Institutes of Health grants (K01HL103176, K08111207, R01 HL078691, HL057263, HL071763, HL080498, HL083156, and R01 HL105301).

Other study co-authors include Razmig G. Kratlian, MD, Ludovic Benard, PhD, Kiyotake Ishikawa, MD, Jaume Aguero, MD, Dennis Ladage, MD, Irene C.Turnbull, MD, Erik Kohlbrenner, BA, Lifan Liang, MD, Jean-Sébastien Hulot, MD, PhD, and Yoshiaki Kawase, MD, from Icahn School of Medicine at Mount Sinai; Bradley A. Maron, MD and the study’s co-senior author Jane A. Leopold, MD, from Brigham and Women’s Hospital and Harvard Medical School in Boston, MA; Christophe Guignabert, PhD, from Hôpital Antoine-Béclère, Clamart, France; Peter Dorfmüller, MD, PhD, and Marc Humbert, MD, PhD, both of the Hôpital Antoine-Béclère and INSERM U999, Centre Chirurgical Marie-Lannelongue, Le Plessis-Robinson, France; Borja Ibanez, MD, from Fundación Centro Nacional de Investigaciones Cardiovasculares, Carlos III (CNIC), Madrid, Spain; and Krisztina Zsebo, PhD, of Celladon Corporation, San Diego, CA.

  • Dr. Hajjar and co-author Dr. Zsebo, have ownership interest in Celladon Corporation, which is developing AAV1.SERCA2a for the treatment of heart failure. Also,
  • Dr. Hajjar and co-authors Dr. Kawase and Dr. Ladage hold intellectual property around SERCA2a gene transfer as a treatment modality for PAH. In addition,
  • co-author Dr. Maron receives funding from Gilead Sciences, Inc. to study experimental pulmonary hypertension.
  • Other study co-authors have no financial interests to declare.

Therapeutic Efficacy of AAV1.SERCA2a in Monocrotaline-Induced Pulmonary Arterial Hypertension

  1. Lahouaria Hadri, PhD;
  2. Razmig G. Kratlian, MD;
  3. Ludovic Benard, PhD;
  4. Bradley A. Maron, MD;
  5. Peter Dorfmüller, MD, PhD;
  6. Dennis Ladage, MD;
  7. Christophe Guignabert, PhD;
  8. Kiyotake Ishikawa, MD;
  9. Jaume Aguero, MD;
  10. Borja Ibanez, MD;
  11. Irene C. Turnbull, MD;
  12. Erik Kohlbrenner, BA;
  13. Lifan Liang, MD;
  14. Krisztina Zsebo, PhD;
  15. Marc Humbert, MD, PhD;
  16. Jean-Sébastien Hulot, MD, PhD;
  17. Yoshiaki Kawase, MD;
  18. Roger J. Hajjar, MD*;
  19. Jane A. Leopold, MD*

+Author Affiliations


  1. From the Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY (L.H., R.G.K., L.B., D.L., K.I., J.A., I.C.T., E.K., L.L., J.-S.H., Y.K., R.J.H.); Cardiovascular Medicine Division, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA (B.A.M., J.A.L.); Hôpital Antoine-Béclère, Clamart, France (P.D., C.G., M.H.); INSERM U999, Centre Chirurgical Marie-Lannelongue, Le Plessis-Robinson, France (P.D., M.H.); Fundación Centro Nacional de Investigaciones Cardiovasculares, Carlos III (CNIC), Madrid, Spain (B.I.); and Celladon Corporation, San Diego, CA (K.Z.).
  1. Correspondence to Lahouaria Hadri, PhD, Cardiovascular Research Center, Box 1030, Icahn School of Medicine at Mount Sinai, 1470 Madison Ave, New York, NY 10029. E-mail lahouaria.hadri@mssm.edu

Abstract

Background—Pulmonary arterial hypertension (PAH) is characterized by dysregulated proliferation of pulmonary artery smooth muscle cells leading to (mal)adaptive vascular remodeling. In the systemic circulation, vascular injury is associated with downregulation of sarcoplasmic reticulum Ca2+-ATPase 2a (SERCA2a) and alterations in Ca2+homeostasis in vascular smooth muscle cells that stimulate proliferation. We, therefore, hypothesized that downregulation of SERCA2a is permissive for pulmonary vascular remodeling and the development of PAH.

Methods and Results—SERCA2a expression was decreased significantly in remodeled pulmonary arteries from patients with PAH and the rat monocrotaline model of PAH in comparison with controls. In human pulmonary artery smooth muscle cells in vitro, SERCA2a overexpression by gene transfer decreased proliferation and migration significantly by inhibiting NFAT/STAT3. Overexpresion of SERCA2a in human pulmonary artery endothelial cells in vitro increased endothelial nitric oxide synthase expression and activation. In monocrotaline rats with established PAH, gene transfer of SERCA2a via intratracheal delivery of aerosolized adeno-associated virus serotype 1 (AAV1) carrying the human SERCA2a gene (AAV1.SERCA2a) decreased pulmonary artery pressure, vascular remodeling, right ventricular hypertrophy, and fibrosis in comparison with monocrotaline-PAH rats treated with a control AAV1 carrying β-galactosidase or saline. In a prevention protocol, aerosolized AAV1.SERCA2a delivered at the time of monocrotaline administration limited adverse hemodynamic profiles and indices of pulmonary and cardiac remodeling in comparison with rats administered AAV1 carrying β-galactosidase or saline.

Conclusions—Downregulation of SERCA2a plays a critical role in modulating the vascular and right ventricular pathophenotype associated with PAH. Selective pulmonary SERCA2a gene transfer may offer benefit as a therapeutic intervention in PAH.

Key Words:

  • Received January 24, 2013.
  • Accepted June 13, 2013.

http://circ.ahajournals.org/content/128/5/512.abstract?sid=9b3b4fcc-e158-4e5d-bb8b-125586e2ec12

Circulation.2013; 128: 512-523 Published online before print June 26, 2013,doi: 10.1161/​CIRCULATIONAHA.113.001585

Part III: Cardiac Gene Therapy: Percutaneous Intra-coronary Artery Infusion for Heart Failure

Etiology of Heart Failure

  • Alcoholic
  • Hypertensive
  • Idiopathic
  • Inflammatory
  • Ischemic
  • Pregnancy-related
  • Toxic
  • Valvular Heart DIsease

Administration of Cardiac Gene Therapy for Heart Failure: via Percutaneous Intra-coronary Artery Infusion

  • Gene delivery to viable myocardium

dominance and coronary artery anatomy from angiography determines infusion scenario

  • Antegrade epicardial coronary artery infusion over 10 minutes

60 mL divided into 1,2,3 infusions depending on anatomy

Delivered via commercially available angiographic injection system & guide or diagnostic catheters

Dr. Roger J. Hajjar of the Mount Sinai School of Medicine will present at the ASGCT 15th Annual Meeting during a Scientific Symposium entitled: Cell and Gene Therapy in Cardiovascular Disease on Wednesday, May 16, 2012 at 8:00 am. Below is a brief preview of his presentation.

Roger J. Hajjar, MD

Mount Sinai School of Medicine

New York, NY

Novel Developments in Gene Therapy for Cardiovascular Diseases

Chronic heart failure is a leading cause of hospitalization affecting nearly 6 million people in the U.S. with 670,000 new cases diagnosed every year. Heart failure leads to about 280,000 deaths annually.

Congestive heart failure remains a progressive disease with a desperate need for innovative therapies to reverse the course of ventricular dysfunction. The most common symptoms of heart failure are shortness of breath, feeling tired and swelling in the ankles, feet, legs and sometimes the abdomen. Recent advances in understanding the molecular basis of myocardial dysfunction, together with the evolution of increasingly efficient gene transfer technology have placed heart failure within reach of gene-based therapies.

One of the key abnormalities in both human and experimental HF is a defect in sarcoplasmic reticulum (SR) function, which controls Ca2+ handling in cardiac myocytes on a beat to beat basis. Deficient SR Ca2+ uptake during relaxation has been identified in failing hearts from both humans and animal models and has been associated with a decrease in the activity of the SR Ca2+-ATPase (SERCA2a).

Over the last ten years we have undertaken a program of targeting important calcium cycling proteins in experimental models of heart by somatic gene transfer. This has led to the completion of a first-in-man phase 1 clinical trial of gene therapy for heart failure using adeno-associated vector (AAV) type 1 carrying SERCA2a. In this Phase I trial, there was evidence of clinically meaningful improvements in functional status and/or cardiac function which were observed in the majority of patients at various time points. The safety profile of AAV gene therapy along with the positive biological signals obtained from this phase 1 trial has led to the initiation and recent completion of a phase 2 trial of AAV1.SERCA2a in NYHA class III/IV patients. In the phase 2 trial, gene transfer of SERCA2a was found to be safe and associated with benefit in clinical outcomes, symptoms, functional status, NT-proBNP and cardiac structure.

The 12 month data presented showed that heart failure, which is a progressive disease, became stabilized in high dose AAV1.SERCA2a-treated patients: heart failure symptoms, exercise tolerance, serum biomarkers and cardiac function essentially improved or remained the same while these parameters deteriorated substantially in patients treated with placebo and concurrent optimal drug and device therapy. More recently, the 2-year CUPID data from long-term follow-up demonstrate a durable benefit in preventing major cardiovascular events.

The recent successful and safe completion of the CUPID trial along with the start of more recent phase 1 trials usher a new era for gene therapy for the treatment of heart failure. Furthermore, novel AAV derivatives with high cardiotropism and resistant to neutralizing antibodies are being developed to target a large number of cardiovascular diseases.

http://www.execinc.com/hosted/emails/asgct/file/Hajjar2(1).pdf

Power Point Presentation on Cardiac Gene Therapy –

VIEW SLIDE SHOW

http://my.americanheart.org/idc/groups/heart-public/@wcm/@global/documents/downloadable/ucm_311680.pdf

Gene Therapy for Heart Failure

  1. Lisa Tilemann,
  2. Kiyotake Ishikawa,
  3. Thomas Weber,
  4. Roger J. Hajjar

+Author Affiliations


  1. From the Cardiovascular Research Center, Mount Sinai Medical Center, New York, NY.
  1. Correspondence to Roger J. Hajjar, MD, Mount Sinai Medical Center, One Gustave Levy Place, Box 1030, New York, NY 10029. E-mail roger.hajjar@mssm.edu

Abstract

Congestive heart failure accounts for half a million deaths per year in the United States. Despite its place among the leading causes of morbidity, pharmacological and mechanic remedies have only been able to slow the progression of the disease. Today’s science has yet to provide a cure, and there are few therapeutic modalities available for patients with advanced heart failure. There is a critical need to explore new therapeutic approaches in heart failure, and gene therapy has emerged as a viable alternative. Recent advances in understanding of the molecular basis of myocardial dysfunction, together with the evolution of increasingly efficient gene transfer technology, have placed heart failure within reach of gene-based therapy. The recent successful and safe completion of a phase 2 trial targeting the sarcoplasmic reticulum calcium ATPase pump (SERCA2a), along with the start of more recent phase 1 trials, opens a new era for gene therapy for the treatment of heart failure.

Circulation Research.2012; 110: 777-793 doi: 10.1161/​CIRCRESAHA.111.252981

Key Words:

  • Received December 8, 2011.
  • Revision received January 29, 2012.
  • Accepted January 30, 2012.

Conclusions 

With a better understanding of the molecular mechanisms associated with heart failure and improved vectors with cardiotropic properties, gene therapy can now be considered as a viable adjunctive treatment to mechanical and pharmacological therapies for heart failure. In the coming years, more targets will emerge that are amenable to genetic manipulations, along with more advanced vector systems, which will undoubtedly lead to safer and more effective clinical trials in gene therapy for heart failure.

http://circres.ahajournals.org/content/110/5/777.full.pdf+html

Hijjar1
Figure 1.

AAV entry. 1 indicates receptor binding and endocytosis; 2, escape into cytoplasm; 3, nuclear import; 4, capsid disassembly; 5, double-strand synthesis; and 6, transcription.

Hijjar2

Figure 2.

Generation of mutant AAV library and directed evolution to identify cardiotropic AAVs. A, Creation of a library of AAVs through DNA shuffling.B, Selection of cardiotropic AAVs through directed evolution.

Hijjar3

Figure 3.

Antegrade coronary artery infusion. A, Coronary artery infusion. The vector is injected through a catheter without interruption of the coronary flow. B, Coronary artery infusion with occlusion of a coronary artery: The vector is injected through the lumen of an inflated angioplasty catheter. C, Coronary artery infusion with simultaneous blocking of a coronary artery and a coronary vein: The vector is injected through an inflated angioplasty catheter and resides in the coronary circulation until both balloons are deflated.

Hijjar4

Figure 4.

V-Focus system and retrograde coronary venous infusion. A, Recirculating antegrade coronary artery infusion: The vector is injected into a coronary artery, collected from the coronary sinus and after oxygenation readministered into the coronary artery. B, Retrograde coronary venous infusion with simultaneous blocking of a coronary artery and a coronary vein: The vector is injected into a coronary vein and resides in the coronary circulation until both balloons are deflated.

Hijjar5

Figure 5.

Direct myocardial injection and pericardial injection. A, Percutaneous myocardial injection: The vector is injected with an injection catheter via an endocardial approach.B, Surgical myocardial injection: The vector is injected via an epicardial approach. C, Percutaneous pericardial injection: The vector is injected via a substernal approach.

Hijjar6

Figure 6.

Excitation-contraction coupling in cardiac myocytes provides multiple targets for gene therapy.

SOURCE

http://circres.ahajournals.org/content/110/5/777.figures-only

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Nanotechnology and HIV/AIDS Treatment

Author: Tilda Barliya, PhD

 

AIDS was first reported in 1981 followed by the identification of HIV as the cause of the disease in 1983 and is now a global pandemic that has become the leading infectious killer of adults worldwide. By 2006, more than 65 million people had been infected with the HIV virus worldwide and 25 million had died of AIDS (Merson MH. The HIV-AIDS pandemic at 25 – the global response. (1, 2). This has caused tremendous social and economic damage worldwide, with developing countries, particularly Sub-Saharan Africa, heavily affected.

A cure for HIV/AIDS has been elusive in almost 30 years of research. Early treatments focused on antiretroviral drugs that were effective only to a certain degree. The first drug, zidovudine, was approved by the US FDA in 1987, leading to the approval of a total of 25 drugs to date, many of which are also available in fixed-dose combinations and generic formulations for use in resource-limited settings (to date, only zidovudine and didanosine are available as true generics in the USA).

However, it was the advent of a class of drugs known as protease inhibitors and the introduction of triple-drug therapy in the mid-1990s that revolutionized HIV/AIDS treatment (3,4). This launched the era of highly active antiretroviral therapy (HAART), where a combination of three or more different classes of drugs are administered simultaneously.

Challenges of HIV/AIDS treatment

  • HIV resides in latent cellular and anatomical reservoirs where current drugs are unable to completely eradicate the virus.
  • Macrophages are major cellular reservoirs, which also contribute to the generation of elusive mutant viral genotypes by serving as the host for viral genetic recombination.
  • Anatomical latent reservoirs include secondary lymphoid tissue, testes, liver, kidney, lungs, the gut and the brain.
  • The major challenge facing current drug regimens is that they do not fully eramacrdicate the virus from these reservoirs; requiring patients take medications for life. Under current treatment, pills are taken daily, resulting in problems of patient adherence. The drugs also have side effects and in some people the virus develops resistance against certain drugs.

Current treatment in HIV/AIDS

The use of the HAART regimen, particularly in the developed world, has resulted in tremendous success in improving the expectancy and quality of lives for patients. However, some HAART regimens have serious side effects and, in all cases, HAART has to be taken for a lifetime, with daily dosing of one or more pills. Due to the need to take the medication daily for a lifetime, patients fail to adhere to the treatment schedule, leading to ineffective drug levels in the body and rebound of viral replication.Some patients also develop resistance to certain combinations of drugs, resulting in failure of the treatment. The absence of complete cure under current treatment underscores the great need for continued efforts in seeking innovative approaches for treatment of HIV/AIDS.

Drug resistance is mainly caused by the high genetic diversity of HIV-1 and the continuous mutation it undergoes. This problem is being addressed with individualized therapy, whereby resistance testing is performed to select a combination of drugs that is most effective for each patient (5). In addition, side effects due to toxicities of the drugs are also a concern. There are reports that patients taking HAART experience increased rates of heart disease, diabetes, liver disease, cancer and accelerated aging. Most experts agree that these effects could be due to the HIV infection itself or co-infection with another virus, such as co-infection with hepatitis C virus resulting in liver disease. However, the toxicities resulting from the drugs used in HAART could also contribute to these effects.

Under current treatment, complete eradication of the virus from the body has not been possible. The major cause for this is that the virus resides in ‘latent reservoirs’ within memory CD4+ T cells and cells of the macrophage–monocyte lineage. A major study recently found that, in addition to acting as latent reservoirs, macrophages significantly contribute to the generation of elusive mutant viral genotypes by serving as the host for viral genetic recombination (6).  The cells that harbor latent HIV are typically concentrated in specific anatomic sites, such as secondary lymphoid tissue, testes, liver, kidney, lungs, gut and the CNS. The eradication of the virus from such reservoirs is critical to the effective long-term treatment of HIV/AIDS patients.

Therefore, there is a great need to explore new approaches for developing nontoxic, lower-dosage treatment modalities that provide more sustained dosing coverage and effectively eradicate the virus from the reservoirs, avoiding the need for lifetime treatments.

Nanotechnology for HIV/AIDS treatment

The use of nanotechnology platforms for delivery of drugs is revolutionizing medicine in many areas of disease treatment.

Nanotechnology-based platforms for systemic delivery of antiretroviral drugs could have similar advantages.

  • Controlled-release delivery systems can enhance their half-lives, keeping them in circulation at therapeutic concentrations for longer periods of time. This could have major implications in improving adherence to the drugs.
  • Nanoscale delivery systems also enhance and modulate the distribution of hydrophobic and hydrophilic drugs into and within different tissues due to their small size. This particular feature of nanoscale delivery systems appears to hold the most promise for their use in clinical treatment and prevention of HIV. Specifically, targeted delivery of antiretroviral drugs to CD4+ T cells and macrophages as well as delivery to the brain and other organ systems could ensure that drugs reach latent reservoirs
  • Moreover, by controlling the release profiles of the delivery systems, drugs could be released over a longer time and at higher effective doses to the specific targets. Figure 1. Various nanoscale drug delivery systems.

Optional treatments:

  •    Antiretroviral drugs
  •    Gene Therapy
  •    Immune Therapy
  •    Prevention

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The use of nanotechnology systems for delivery of antiretroviral drugs has been extensively reviewed by Nowacek et al. and Amiji et al. (7,8).

In a recent study based on polymeric systems, nanosuspensions (200 nm) of the drug rilpivirine (TMC278) stabilized by polyethylene. A series of experiments by Dou et al. showed that nanosuspension of the drug indinavir can be stabilized by a surfactant system comprised of Lipoid E80 for effective delivery to various tissues. The indinavir nanosuspensions were loaded into macrophages and their uptake was investigated. Macrophages loaded with indinavir nanosuspensions were then injected intravenously into mice, resulting in a high distribution in the lungs, liver and spleen. More significantly, the intravenous administration of a single dose of the nanoparticle-loaded macrophages in a rodent mouse model of HIV brain infection resulted in significant antiviral activity in the brain and produced measureable drug levels in the blood up to 14 days post-treatment.polypropylene glycol (poloxamer 338) and PEGylated tocopheryl succinate ester (TPGS 1000) were studied in dogs and mice. A single-dose administration of the drug in nanosuspensions resulted in sustained release over 3 months in dogs and 3 weeks in mice, compared with a half-life of 38 h for free drug. These results serve as a proof-of-concept that nanoscale drug delivery may potentially lower dosing frequency and improve adherence.

Active targeting strategies have also been employed for antiretroviral drug delivery. Macrophages, which are the major HIV reservoir cells, have various receptors on their surface such as formyl peptide, mannose, galactose and Fc receptors, which could be utilized for receptor-mediated internalization. The drug stavudine was encapsulated using various liposomes (120–200 nm) conjugated with mannose and galactose, resulting in increased cellular uptake compared with free drug or plain liposomes, and generating significant level of the drug in liver, spleen and lungs. Stavudine is a water-soluble drug with a very short serum half-life (1 h). Hence, the increased cellular uptake and sustained release in the tissues afforded by targeted liposomes is a major improvement compared with free drug. The drug zidovudine, with half-life of 1 h and low solubility, was also encapsulated in a mannose-targeted liposome made from stearylamine, showing increased localization in lymph node and spleen. An important factor to consider here is that although most of the nucleoside drugs such as stavudine and zidovudine have short serum half-lives, the clinically relevant half-life is that of the intracellular triphosphate form of the drug. For example, despite zidovudine’s 1 h half-life in plasma, it is dosed twice daily based on intracellular pharmacokinetic and clinical efficacy data. Therefore, future nanotechnology-based delivery systems will have to focus in showing significant increase of the half-lives of the encapsulated drugs to achieve a less frequent dosing such as once weekly, once-monthly or even less.

Gene Therapy for HIV/AIDS

In addition to improving existing antiretroviral therapy, there are ongoing efforts to discover alternative approaches for treatment of HIV/AIDS. One promising alternative approach is gene therapy, in which a gene is inserted into a cell to interfere with viral infection or replication. Other nucleic acid-based compounds, such as DNA, siRNA, RNA decoys, ribozymes and aptamers or protein-based agents such as fusion inhibitors and zinc-finger nucleases can also be used to interfere with viral replication.

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RNAi is also considered to have therapeutic potential for HIV/AIDS. Gene silencing is induced by double stranded siRNA, which targets for destruction

he mRNA of the gene of interest. For HIV/AIDS, RNAi can either target the various stages of the viral replication cycle or various cellular targets involved in viral infection such as CD4, CCR5, and/or CXCR4, the major cell surface co-receptors responsible for viral entry. HIV replicates by reverse transcription to form DNA and uses the DNA to produce copies of its mRNA for protein synthesis; siRNA therapy could be used to knock down this viral mRNA. As with other gene therapy techniques, delivery of siRNA to specific cells and tissues has been the major challenge in realizing the potential of RNAi.

New nanotechnology platforms are tackling this problem by providing nonviral alternatives for effective and safe delivery. The first nontargeted delivery of siRNA in humans via self-assembling, cyclodextrin polymer-based nanoparticles for cancer treatment have recently entered Phase I clinical trials.

Although at an early stage, nonviral delivery of siRNA for treatment of HIV infection is also gaining ground. A fusion protein, with a peptide transduction domain and a double stranded RNA-binding domain, was used to encapsulate and deliver siRNA to T cells in vivo. CD4- and CD8-specific siRNA delivery caused RNAi responses with no adverse effects such as cyto-toxicity or immune stimulation. Similarly, a protamine-antibody fusion protein-based siRNA delivery demonstrated that siRNA knockdown of the gag gene can inhibit HIV replication in primary T cells

Single-walled nanotubes were shown to deliver CXCR4 and CD4 specific siRNA to human T cells and peripheral blood mononuclear cells. Up to 90% knockdown of CXCR4 receptors and up to 60% knockdown of CD4 expression on T cells was observed while the knockdown of CXCR4 receptors on peripheral blood mononuclear cells was as high as 60%. In a separate study, amino-terminated carbosilane dendrimers (with interior carbon-silicon bonds) were used for delivery of siRNA to HIV-infected lymphocytes.

These pioneering studies demonstrate that nonviral siRNA delivery is possible for HIV/AIDS treatment. However, more work needs to be done in optimizing the delivery systems and utilizing designs for efficient targeting and intracellular delivery. The recent developments in polymer- and liposome-based siRNA delivery systems could be optimized for targeting cells that are infected with HIV, such as T cells and macrophages. Moreover, since HIV mutates and has multiple strains with different genetic sequences, combination siRNA therapy targeting multiple genes should be pursued. For these applications, nanotechnology platforms with capability for co-delivery and targeting need to be developed specifically for HIV-susceptible cells. A macrophage and T-cell-targeted and nanotechnology-based combination gene therapy may be a promising platform for efficient HIV/AIDS treatment.

Immunotherapy for HIV/AIDS

The various treatment approaches described above focus on treating HIV/AIDS by directly targeting HIV at the level of the host cell or the virus itself. An alternative approach is immunotherapy aimed at modulating the immune response against HIV. CD8+ cytotoxic T-cell responses to acute HIV infection appear to be relatively normal, while neutralizing antibody production by B cells is delayed or even absent.

Immunotherapy is a treatment approach involving the use of immunomodulatory agents to modulate the immune response against a disease. Similar to vaccines, it is based on immunization of individuals with various immunologic formulations; however, the purpose is to treat HIV-infected patients as opposed to protect healthy individuals (preventive vaccines will be discussed in an upcoming section). The various immunotherapy approaches for HIV/AIDS could be based on delivering cytokines (such as IL-2, IL-7 and IL-15) or antigens. The development of cellular immunity, and to a large degree humoral immunity, requires antigen-presenting cells (APCs) to process and present antigens to CD4+and CD8+ T cells. Dendritic cells (DCs) are the quintessential professional APCs responsible for initiating and orchestrating the development of cellular and humoral (antibody) immunity.

Various polymeric systems have been explored for in vivo targeting of DCs and delivery of small molecules, proteins or DNAs showing potential for immunotherapy. Poly(ethylene glycol) (PEG) stabilized poly(propylene sulfide) polymer nanoparticles accumulated in DCs in lymph nodes. Following nanoparticle injection, DCs containing nanoparticles accumulated in lymph nodes, peaking at 4 days with 40–50% of DCs and other APCs having internalized nanoparticles.

In another study, nanoparticles of the copolymer poly(D,L-lacticide-co-glycolide) (PLGA) showed efficient delivery of antigens to murine bone marrow-derived DCs in vitro, suggesting their potential use in immunotherapy. More recently, a very interesting work showed that HIV p24 protein adsorbed on the surface of surfactant-free anionic poly(D,L-lactide) (PLA) nanoparticles were efficiently taken-up by mouse DCs, inducing DC maturation. he p24-nanoparticles induced enhanced cellular and mucosal immune responses in mice. Although this targeting is seen in ex vivo-generated DCs and not in vivo DCs, the efficient delivery of the antigen to DCs through the nanoparticles is an important demonstration that may eventually be applied to in vivo DC targeting.

Clinical Trial

he most clinically advanced application of nanotechnology for immunotherapy of HIV/AIDS is the DermaVir patch that has reached Phase II clinical trials (9). DermaVir is a targeted nanoparticle system based on polyethyleimine mannose (PEIm), glucose and HIV antigen coding DNA plasmid formulated into nanoparticles (~100 nm) and administered under a patch after a skin preparation. The nanoparticles are delivered to epidermal Langerhans cells that trap the nanoparticles and mature to become highly immunogenic on their way to the lymph nodes. Mature DCs containing the nanoparticles present antigens to T cells inducing cellular immunity. Preclinical studies and Phase I clinical trials showed safety and tolerability of the DermaVir patch, which led the progression to Phase II trials. This is the first nanotechnology-based immunotherapy for HIV/AIDS that has reached the clinic and encourages further work in this area.

Table 1

Summary of nanotechnology-based treatment approaches for HIV/AIDS.

Type of therapy Therapeutic agent (drug or gene) Nanotechnology delivery platform Development stage Refs.
Antiretroviral therapy Rilpivirine (TMC278) Poloxamer 338/TPGS 1000 Preclinical [35]
Indinavir Liposome-laden macrophages Preclinical [3638]
Stavudine Mannose- and galactose-targeted liposome Preclinical [3941]
Zidovudine Mannose-targeted liposome Preclinical [42]
Efavirenz Mannose-targeted dendrimer Preclinical [43,45]
Lamivudine Mannose-targeted dendrimer Preclinical [46]
Nanomaterials Fullerene derivatives Preclinical [4955]
Dendrimers Preclinical [56,57]
Silver nanoparticles Preclinical [58,59]
SDC-1721/gold nanoparticles Gold nanoparticles Preclinical [60]
Gene therapy siRNA Peptide fusion proteins, protamine–antibody fusion proteins, dendrimers, single walled carbon nanotubes, peptide–antibody conjugates Preclinical [7781]
Immunotherapy P24 protein Poly (D,L-lactide) nanoparticles/dendritic cells Preclinical [98]
Plasmid DNA Mannose-targeted polyethyleimine polymers Phase II clinical trials [99]

Note:  to open the references in the table 1, please go to ref 1 in this post to see full ref info.

Nanotechnology for HIV/AIDS prevention

The search for a safe and effective HIV/AIDS vaccine has been challenging in the almost three decades since the discovery of the disease. Recently, high-profile clinical trial failures have prompted great debate over the vaccine research, with some suggesting the need for a major focus on fundamental research, with fewer efforts on clinical trials.

The major challenges in the development of a preventive HIV/AIDS vaccine have been the extensive viral strain and sequence diversity, viral evasion of humoral and cellular immune responses, coupled with the lack of methods to elicit broadly reactive neutralizing antibodies and cytotoxic T cells. The challenge associated with delivery of any exogenous antigen (such as nanoparticles) to APCs, is that exogenous antigens require specialized ‘cross-presentation’ in order to be presented by MHC class I and activate CD8+cytotoxic T cells.

his requirement for cytosolic delivery of antigens and cross-presentation represents yet another hurdle for HIV intracellular antigen vaccine, but potentially an advantage of nanodelivery. Humoral responses (neutralizing antibodies produced by B cells) are generated to intact antigen presented on the surface for the virus, or nanoparticles, but these humoral responses typically require ‘help’ from CD4+ T cells, but rather both. Nanoparticles have potential as adjuvants and delivery systems for vaccines. Table 2 present the different approaches.

Table 2

Summary of nanotechnology developments for prevention of HIV/AIDS.

Type of preventive agent Antigen/adjuvant or drug Nanotechnology platform Development stage Refs.
Protein or peptide vaccine gp41, gp120, gp160, p24, Env, Gag, Tat Liposomes, nanoemulsion, MF59, PLA nanoparticles, poly(γ-glutamic acid) nanoparticles Preclinical [108111]
[119120]
[122125]
[128130]
DNA vaccine env, rev, gag, tat, CpG ODN Liposomes, nanoemulsion, PLA nanoparticles Preclinical [115,121]
Inactivated viral particle Inactivated HIV viral particle Polystyrene nanospheres Preclinical [126127]
Microbicides L-lysine dendrimer L-lysine dendrimer Phase I/II [136138]
PLGA nanoparticles
PSC-RANTES PLGA Preclinical [139]
siRNA Nanoparticles, lipids, cholesterol conjugation Preclinical [141144]

ODN: Oligonucleotides; PLA: Poly(D,L-lactide); PLGA: Poly(D,L-lacticide-co-glycolide).

Note:  to open the references in the table 2, please go to ref 1 in this post to see full ref info.

 

Summary

Nanotechnology can impact the treatment and prevention of HIV/AIDS with various innovative approaches. Treatment options may be improved using nanotechnology platforms for delivery of antiretroviral drugs. Controlled and sustained release of the drugs could improve patient adherence to drug regimens, increasing treatment effectiveness.

While there is exciting potential for nanomedicine in the treatment of HIV/AIDS, challenges remain to be overcome before the potential is realized. These include toxicity of nanomaterials, stability of nanoparticles in physiological conditions and their scalability for large-scale production. These are challenges general to all areas of nanomedicine and various works are underway to tackle them.

Another important consideration in investigating nanotechnology-based systems for HIV/AIDS is the economic aspect, as the hardest hit and most vulnerable populations reside in underdeveloped and economically poor countries. In the case of antiretroviral therapy, nanotherapeutics may increase the overall cost of treatment, reducing the overall value. However, if the nanotherapeutics could improve patient adherence by reducing dosing frequency as expected, and furthermore, if they can eradicate viral reservoirs leading to a sterile immunity, these advantages may effectively offset the added cost.

 

Ref:

1. Mamo T, Moseman EA., Kolishetti N., Salvadoe-Morales C., Shi J., Kuritzkes DR., Langer R., von-Adrian U and Farokhzad OF.   Emerging nanotechnology approaches for HIV/AIDS treatment and prevention. Nanomedicine (Lond) 2010; 5(2): 269-295.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2861897/

2. Merson MH. The HIV-AIDS pandemic at 25 – the global response. N Engl J Med.2006;354(23):2414–2417

3. Walensky RP, Paltiel AD, Losina E, et al. The survival benefits of AIDS treatment in the United States. J Infect Dis. 2006;194(1):11–19

4. Richman DD, Margolis DM, Delaney M, Greene WC, Hazuda D, Pomerantz RJ. The challenge of finding a cure for HIV infection. Science. 2009;323(5919):1304–1307)

5.Sax PE, Cohen CJ, Kuritzkes DR. HIV Essentials. Physicians’ Press; Royal Oak, MI, USA: 2007.

6. Lamers SL, Salemi M, Galligan DC, et al. Extensive HIV-1 intra-host recombination is common in tissues with abnormal histopathology. PLoS One. 2009;4(3):E5065.

7. Vyas TK, Shah L, Amiji MM. Nanoparticulate drug carriers for delivery of HIV/AIDS therapy to viral reservoir sites. Expert Opin Drug Deliv. 2006;3(5):613–628.

8. Amiji MM, Vyas TK, Shah LK. Role of nanotechnology in HIV/AIDS treatment: Potential to overcome the viral reservoir challenge. Discov Med. 2006;6(34):157–162

9. Lori F, Calarota SA, Lisziewicz J. Nanochemistry-based immunotherapy for HIV-1. Curr Med Chem. 2007;14(18):1911–1919

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Curator/Reporter: Aviral Vatsa PhD MBBS

This post is in the second part of the reviews that focuses on the current status of drug delivery to bone and the issues facing this field. The first part can be accessed here

Annual treatment costs for musculoskeletal diseases in the US are roughly 7.7% (~ $849 billion) of total gross domestic product. Such disorders are the main cause of physical disability in US. Almost half of all chronic conditions in people can be attributed to bone and joint disorders. In addition there is increasing ageing population and associated increases in osteoporosis and other diseases, rising incidences of degenerative intervertebral disk diseases and numbers of revision orthopedic arthroplasty surgeries, and increases in spinal fusions. All these factors contribute towards the increasing requirement of bone regeneration and reconstruction methods and products. Delivery of therapeutic grade products to bone has various challenges. Parenteral administration limits the efficient delivery of drugs to the required site of injury and local delivery methods are often expensive and invasive. The theme issue of Advance Drug Delivery reviews focuses on the current status of drug delivery to bone and the issues facing this field. Here is the second part of these reviews and research articles.

1. Targeting polymer therapeutics to bone [1]

Abstract

An aging population in the developing world has led to an increase in musculoskeletal diseases such as osteoporosis and bone metastases. Left untreated many bone diseases cause debilitating pain and in the case of cancer, death. Many potential drugs are effective in treating diseases but result in side effects preventing their efficacy in the clinic. Bone, however, provides a unique environment of inorganic solids, which can be exploited in order to effectively target drugs to diseased tissue. By integration of bone targeting moieties to drug-carrying water-soluble polymers, the payload to diseased area can be increased while side effects decreased. The realization of clinically relevant bone targeted polymer therapeutics depends on (1) understanding bone targeting moiety interactions, (2) development of controlled drug delivery systems, as well as (3) understanding drug interactions. The latter makes it possible to develop bone targeted synergistic drug delivery systems.


2. Development of macromolecular prodrug for rheumatoid arthritis [2]

Abstract

Rheumatoid arthritis (RA) is a chronic autoimmune disease that is considered to be one of the major public health problems worldwide. The development of therapies that target tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and co-stimulatory pathways that regulate the immune system have revolutionized the care of patients with RA. Despite these advances, many patients continue to experience symptomatic and functional impairment. To address this issue, more recent therapies that have been developed are designed to target intracellular signaling pathways involved in immunoregulation. Though this approach has been encouraging, there have been major challenges with respect to off-target organ side effects and systemic toxicities related to the widespread distribution of these signaling pathways in multiple cell types and tissues. These limitations have led to an increasing interest in the development of strategies for the macromolecularization of anti-rheumatic drugs, which could target them to the inflamed joints. This approach enhances the efficacy of the therapeutic agent with respect to synovial inflammation, while markedly reducing non-target organ adverse side effects. In this manuscript, we provide a comprehensive overview of the rational design and optimization of macromolecular prodrugs for treatment of RA. The superior and the sustained efficacy of the prodrug may be partially attributed to their Extravasation through Leaky Vasculature and subsequent Inflammatory cell-mediated Sequestration (ELVIS) in the arthritic joints. This biologic process provides a plausible mechanism, by which macromolecular prodrugs preferentially target arthritic joints and illustrates the potential benefits of applying this therapeutic strategy to the treatment of other inflammatory diseases.

 

3. Peptide-based delivery to bone [3]

Abstract

Peptides are attractive as novel therapeutic reagents, since they are flexible in adopting and mimicking the local structural features of proteins. Versatile capabilities to perform organic synthetic manipulations are another unique feature of peptides compared to protein-based medicines, such as antibodies. On the other hand, a disadvantage of using a peptide for a therapeutic purpose is its low stability and/or high level of aggregation. During the past two decades, numerous peptides were developed for the treatment of bone diseases, and some peptides have already been used for local applications to repair bone defects in the clinic. However, very few peptides have the ability to form bone themselves. We herein summarize the effects of the therapeutic peptides on bone loss and/or local bone defects, including the results from basic studies. We also herein describe some possible methods for overcoming the obstacles associated with using therapeutic peptide candidates.


4. Growth factor delivery: How surface interactions modulate release in vitro and in vivo [4]

Abstract

Biomaterial scaffolds have been extensively used to deliver growth factors to induce new bone formation. The pharmacokinetics of growth factor delivery has been a critical regulator of their clinical success. This review will focus on the surface interactions that control the non-covalent incorporation of growth factors into scaffolds and the mechanisms that control growth factor release from clinically relevant biomaterials. We will focus on the delivery of recombinant human bone morphogenetic protein-2 from materials currently used in the clinical practice, but also suggest how general mechanisms that control growth factor incorporation and release delineated with this growth factor could extend to other systems. A better understanding of the changing mechanisms that control growth factor release during the different stages of preclinical development could instruct the development of future scaffolds for currently untreatable injuries and diseases.


5. Biomaterial delivery of morphogens to mimic the natural healing cascade in bone[5]

Abstract

Complications in treatment of large bone defects using bone grafting still remain. Our understanding of the endogenous bone regeneration cascade has inspired the exploration of a wide variety of growth factors (GFs) in an effort to mimic the natural signaling that controls bone healing. Biomaterial-based delivery of single exogenous GFs has shown therapeutic efficacy, and this likely relates to its ability to recruit and promote replication of cells involved in tissue development and the healing process. However, as the natural bone healing cascade involves the action of multiple factors, each acting in a specific spatiotemporal pattern, strategies aiming to mimic the critical aspects of this process will likely benefit from the usage of multiple therapeutic agents. This article reviews the current status of approaches to deliver single GFs, as well as ongoing efforts to develop sophisticated delivery platforms to deliver multiple lineage-directing morphogens (multiple GFs) during bone healing.

6. Studies of bone morphogenetic protein-based surgical repair[6]

Abstract

Over the past several decades, recombinant human bone morphogenetic proteins (rhBMPs) have been the most extensively studied and widely used osteoinductive agents for clinical bone repair. Since rhBMP-2 and rhBMP-7 were cleared by the U.S. Food and Drug Administration for certain clinical uses, millions of patients worldwide have been treated with rhBMPs for various musculoskeletal disorders. Current clinical applications include treatment of long bone fracture non-unions, spinal surgeries, and oral maxillofacial surgeries. Considering the growing number of recent publications related to clincal research of rhBMPs, there exists enormous promise for these proteins to be used in bone regenerative medicine. The authors take this opportunity to review the rhBMP literature paying specific attention to the current applications of rhBMPs in bone repair and spine surgery. The prospective future of rhBMPs delivered in combination with tissue engineered scaffolds is also reviewed.


7. Strategies for controlled delivery of growth factors and cells for bone regeneration[7]

Abstract

The controlled delivery of growth factors and cells within biomaterial carriers can enhance and accelerate functional bone formation. The carrier system can be designed with pre-programmed release kinetics to deliver bioactive molecules in a localized, spatiotemporal manner most similar to the natural wound healing process. The carrier can also act as an extracellular matrix-mimicking substrate for promoting osteoprogenitor cellular infiltration and proliferation for integrative tissue repair. This review discusses the role of various regenerative factors involved in bone healing and their appropriate combinations with different delivery systems for augmenting bone regeneration. The general requirements of protein, cell and gene therapy are described, with elaboration on how the selection of materials, configurations and processing affects growth factor and cell delivery and regenerative efficacy in both in vitro and in vivo applications for bone tissue engineering.

8. Bone repair cells for craniofacial regeneration[8]

Abstract

Reconstruction of complex craniofacial deformities is a clinical challenge in situations of injury, congenital defects or disease. The use of cell-based therapies represents one of the most advanced methods for enhancing the regenerative response for craniofacial wound healing. Both somatic and stem cells have been adopted in the treatment of complex osseous defects and advances have been made in finding the most adequate scaffold for the delivery of cell therapies in human regenerative medicine. As an example of such approaches for clinical application for craniofacial regeneration, Ixmyelocel-T or bone repair cells are a source of bone marrow derived stem and progenitor cells. They are produced through the use of single pass perfusion bioreactors for CD90+ mesenchymal stem cells and CD14+ monocyte/macrophage progenitor cells. The application of ixmyelocel-T has shown potential in the regeneration of muscular, vascular, nervous and osseous tissue. The purpose of this manuscript is to highlight cell therapies used to repair bony and soft tissue defects in the oral and craniofacial complex. The field at this point remains at an early stage, however this review will provide insights into the progress being made using cell therapies for eventual development into clinical practice.


9. Gene therapy approaches to regenerating bone[9]

Abstract

Bone formation and regeneration therapies continue to require optimization and improvement because many skeletal disorders remain undertreated. Clinical solutions to nonunion fractures and osteoporotic vertebral compression fractures, for example, remain suboptimal and better therapeutic approaches must be created. The widespread use of recombinant human bone morphogenetic proteins (rhBMPs) for spine fusion was recently questioned by a series of reports in a special issue of The Spine Journal, which elucidated the side effects and complications of direct rhBMP treatments. Gene therapy – both direct (in vivo) and cell-mediated (ex vivo) – has long been studied extensively to provide much needed improvements in bone regeneration. In this article, we review recent advances in gene therapy research whose aims are in vivo or ex vivo bone regeneration or formation. We examine appropriate vectors, safety issues, and rates of bone formation. The use of animal models and their relevance for translation of research results to the clinical setting are also discussed in order to provide the reader with a critical view. Finally, we elucidate the main challenges and hurdles faced by gene therapy aimed at bone regeneration as well as expected future trends in this field.

10. Gene delivery to bone[10]

Abstract

Gene delivery to bone is useful both as an experimental tool and as a potential therapeutic strategy. Among its advantages over protein delivery are the potential for directed, sustained and regulated expression of authentically processed, nascent proteins. Although no clinical trials have been initiated, there is a substantial pre-clinical literature documenting the successful transfer of genes to bone, and their intraosseous expression. Recombinant vectors derived from adenovirus, retrovirus and lentivirus, as well as non-viral vectors, have been used for this purpose. Both ex vivo and in vivo strategies, including gene-activated matrices, have been explored. Ex vivo delivery has often employed mesenchymal stem cells (MSCs), partly because of their ability to differentiate into osteoblasts. MSCs also have the potential to home to bone after systemic administration, which could serve as a useful way to deliver transgenes in a disseminated fashion for the treatment of diseases affecting the whole skeleton, such as osteoporosis orosteogenesis imperfecta. Local delivery of osteogenic transgenes, particularly those encoding bone morphogenetic proteins, has shown great promise in a number of applications where it is necessary to regenerate bone. These include healing large segmental defects in long bones and the cranium, as well as spinal fusion and treating avascular necrosis.

11. RNA therapeutics targeting osteoclast-mediated excessive bone resorption[11]

Abstract

RNA interference (RNAi) is a sequence-specific post-transcriptional gene silencing technique developed with dramatically increasing utility for both scientific and therapeutic purposes. Short interfering RNA (siRNA) is currently exploited to regulate protein expression relevant to many therapeutic applications, and commonly used as a tool for elucidating disease-associated genes. Osteoporosis and their associated osteoporotic fragility fractures in both men and women are rapidly becoming a global healthcare crisis as average life expectancy increases worldwide. New therapeutics are needed for this increasing patient population. This review describes the diversity of molecular targets suitable for RNAi-based gene knock down in osteoclasts to control osteoclast-mediated excessive bone resorption. We identify strategies for developing targeted siRNA delivery and efficient gene silencing, and describe opportunities and challenges of introducing siRNA as a therapeutic approach to hard and connective tissue disorders.

Bibliography

[1] S. A. Low and J. Kopeček, “Targeting polymer therapeutics to bone,” Advanced Drug Delivery Reviews, vol. 64, no. 12, pp. 1189–1204, Sep. 2012.

[2] F. Yuan, L. Quan, L. Cui, S. R. Goldring, and D. Wang, “Development of macromolecular prodrug for rheumatoid arthritis,” Advanced Drug Delivery Reviews, vol. 64, no. 12, pp. 1205–1219, Sep. 2012.

[3] K. Aoki, N. Alles, N. Soysa, and K. Ohya, “Peptide-based delivery to bone,” Advanced Drug Delivery Reviews, vol. 64, no. 12, pp. 1220–1238, Sep. 2012.

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Author and Curator: Ritu Saxena, Ph.D.

Consultants: Aviva Lev-Ari, PhD, RN and Pnina G. Abir-Am, PhD

CONTENT:

Section I   : Mitochondrial diseases and molecular understanding

Section II  : Diagnosis and therapy of mitochondrial diseases

Section III: Mitochondria, metabolic syndrome and research

I. MITOCHONDRIAL DISEASES and MOLECULAR UNDERSTANDING

Mitochondrial cytopathy in adults – current understanding:

Mitochondrial cytopathies are a diverse group of inherited and acquired disorders that result in inadequate energy production leading to illnesses. Several syndromes have been linked to mutations in mitochondrial DNA. Some key features common to mitochondrial diseases are listed as follows:

  • Diverse manifestations of mitochondrial diseases: Although all mitochondrial diseases have the same characteristic of inadequate energy production as compared to the demand, they seem to show diverse manifestations in the form of organs being affected, age of onset and the rate of progression. Reason lies in the unique genetic makeup of mitochondria. The percentage of mtDNA carrying defects varies when the ovum divides and one daughter cells receiving more defective mtDNA and the other receiving less. Hence, successive divisions may lead to accumulation of defects in one of the developing organs or tissues. Since the process in which defective mtDNA becomes concentrated in an organ is random, this may account for the differing manifestations among patients with the same genetic defect. Also, somatic mutations and mutations occurring as a result of exposure to environmental toxins may cause mitochondrial diseases.

As stated by Robert K. Naviaux, founder and co-director of the Mitochondrial and Metabolic Disease Center (MMDC) at the University of California, San Diego;  

“It is a hallmark of mitochondrial diseases that identical mtDNA mutations may not produce identical diseases…the converse is also true, different mutations can lead to the same diseases.”

  • Postmitotic tissues are more vulnerable to mitochondrial diseases: Postmitotic tissues such as those in the brain, muscles, nerves, retinas, and kidneys, are vulnerable for several reasons. Apart from the fact that these tissues have high-energy demands, healthier neighboring cells unlike that observed in skin cannot replace the diseased cells. Thus, mutations in mtDNA accumulate over a period of time resulting in progressive dysfunction of individual cells and hence the organ itself.
  • High rate of mtDNA mutation: MtDNA mutates at rate that is six-seven times higher than the rate of mutation of nuclear DNA. First reason is the absence of histones on mtDNA and second is the exposure of mtDNA to free radicals due to their close proximity to electron transport chain. Additionally, lack of DNA repair enzymes results in mutant tRNA, rRNA and protein transcripts

Spectrum of mitochondrial diseases:

Following is the list of mitochondrial diseases occurring as a result of either mtDNA mutations, alteration in mitochondrial function or those diseases that sometimes might be associated with mitochondrial dysfunction.

  • Disorders associated with mtDNA mutations-

MELAS, MERRF, NARP, Myoneurogastrointestinal disorder and encephalopathy (MNGIE), Pearson Marrow syndrome Kearns-Sayre-CPEO, Leber hereditary optic neuropathy (LHON), Aminoglycoside-associated deafness, Diabetes with deafness

  • Mendelian disorders of mitochondrial function related to fuel homeostasis-

Luft disease, Leigh syndrome (Complex I, COX, PDH), Alpers Disease, MCAD, SCAD, SCHAD, VLCAD, LCHAD, Glutaric aciduria II, Lethal infantile cardiomyopathy, Friedreich ataxia, Maturity onset diabetes of young Malignant hyperthermia, Disorders of ketone utilization, mtDNA depletion syndrome, Reversible COX deficiency of infancy, Various defects of the Krebs Cycle, Pyruvate dehydrogenase deficiency, Pyruvate carboxylase deficiency, Fumarase deficiency, Carnitine palmitoyl transferase deficiency

  • Disorders sometimes associated with mitochondrial function-

Hemochromatosis, Wilson disease, Batten disease, Huntington disease, Menkes disease, Lesch-Nyhan syndrome, Aging, Type II diabetes mellitus, Atherosclerotic heart disease, Parkinson disease, Alzheimer dementia, Congestive heart failure, Niacin-responsive hypercholesterolemia, Postpartum cardiomyopathy, Alcoholic myopathy, Cancer metastasis, Irritable bowel syndrome Gastroparesis-GI dysmotility, Multiple sclerosis, Systemic lupus erythematosis, Rheumatoid arthritis.

II. DIAGNOSIS AND THERAPY OF MITOCHONDRIAL DISEASES

Diagnosis:

Owing to the diversity of symptoms, there is no accepted criterion for diagnosis. Also, due to overlapping symptoms of several diseases with those of mitochondrial dysfunction illnesses, it is important to evaluate the patient for other conditions. A diagnosis could involve combination of molecular genetic, pathologic, or biochemical data in a patient who has clinical features consistent with the diagnosis including mutational analysis on blood lymphocytes and possibly muscle biopsy for visual and biochemical analysis.

The two main biochemical features in most mtDNA disorders are:

  1. Respiratory chain deficiency and
  2. Lactic acidosis.

Skeletal muscle is chosen to study the pathogenic consequence of mtDNA mutations because of the formation of ragged-red fibers (RRF) through mitochondrial proliferation and massive mitochondrial accumulation in many pathogenic situations. RRF can be detected in two ways. Mitochondrial fibers in a subset of these fibers are shown by red or purple stained area by Gomori trichrome stain; the normal or less-affected fibers stain blue or turquoise. Deep purple areas show accumulations of mitochondria as activity of succinate dehydrogenase (SDH) in the case of mitochondrial mutation.

The primary care physician should remember this relatively simple rule of thumb: “When a common disease has features that set it apart from the pack, or involves 3 or more organ systems, think mitochondria.”

Treatment:

There are no cures for mitochondrial diseases; therefore, the treatment is focused on alleviating symptoms and enabling normal functioning of the affected organs. Most patients have used cofactor and vitamins; however, there is no overwhelming evidence that they are helpful in most patients.

  • Coenzyme Q10 (CoQ10) is the best-known cofactor used in treating mitochondrial cytopathies with no known side effects. CoQ10, residing in the inner mitochondrial membrane, functions as the mobile electron carrier and is a powerful antioxidant with benefits such as reduction in lactic acid levels, improved muscle strength, decreased muscle fatigue and so on.
  • Levocarnitine (L-carnitine, carnitine), is a cofactor required for the metabolism of fatty acids. Levocarnitine therapy improves strength, reversal of cardiomyopathy, and improved gastrointestinal motility, which can be a major benefit to those with poor motility due to their disease. Intestinal cramping and pain are the major side effects.
  • Creatine phosphate, synthesized from creatine can accumulate in small amounts in the body, and can act as storage for a high-energy phosphate bond. Muscular creatine may be depleted in mitochondrial cytopathy, and supplemental creatine phosphate has been shown to be helpful in some patients with weakness due to their disease.
  • B Vitamin, are necessary for the function of several enzymes associated with energy production. The need for supplemental B vitamin therapy is not proven, aside from rare cases of thiamine (vitamin B1)-responsive pyruvate dehydrogenase deficiency.

Research – Restriction enzyme for gene therapy of Mitochondria diseases:

Mitochondrial DNA (mtDNA) is the only extrachromosomal DNA in humans and defects in this genome are now recognized as important causes of various diseases. Presently, there is no effective treatment for patients suffering from diseases that harbor mutations in mtDNA.

Tanaka et al discovered a gene therapy method to treat a mitochondrial disease associated with mtDNA heteroplasmy. Heteroplasmy is where mutant and wild-type mtDNA molecules co-exist within cells. This syndrome of neurogenic muscle weakness, ataxia and retinitis pigmentosa (NARP) is caused by mutations in mtDNA leading to amino acid replacement in the resulting protein that codes for a subunit of mitochondrial ATP synthase. Level of mutant mtDNA is crucial for the disease as above a certain threshold level of mtDNA, the disease becomes biochemically and clinically apparent. Authors hypothesized that a possible method to treat patients was by selectively destroying mutant mtDNA, thereby only allowing propagation of wild-type mtDNA. Since restriction endonucleases can recognize highly specific sequences, they were utilized for gene therapy. Tanaka et al utilized Sma1, a restriction endonuclease to destroy mutant mtDNA, leading to increase in wild-type mtDNA levels.

Thus, authors concluded, “ the present results indicate that the use of a mitochondrion-targeted restriction enzyme which specifically recognizes a mutant mtDNA provides a novel strategy for gene therapy of mitochondrial diseases.”

III. MITOCHONDRIA, METABOLIC SYNDROME & RESEARCH

Mitochondria:

Mitochondria are double-membrane organelles located in the cytoplasm and often referred to as the “powerhouse” of the cell. In simple terms, they convert energy into forms that are usable by the cell. Mitochondria are semi-autonomous in that they are only partially dependent on the cell to replicate and grow. They have their own DNA, ribosomes, and can make their own proteins. They are the sites of cellular respiration that generates fuel for the cell’s activities. Mitochondria are also involved in other cell processes such as cell division, cellular growth and cell death. Multiple essential cellular functions are mediated by thousands of mitochondrial-specific proteins, encoded by both the nuclear and mitochondrial genomes.

Interestingly, mitochondria take on many different shapes and along with serving several different metabolic functions. In fact, each mitochondrion’s shape is characteristic of the specialized cell in which it resides. The number of mitochondria too varies in difference cell types, with as high as 500-2000 in some nucleated cells and as low as zero in RBCs and 2-6 in platelets.

The standard sequence to which all human mtNDNA is compared is referred to as the “Cambridge Sequence.” It was sequenced from several different human mtDNAs by a Medical Research Council (MRC) labora- tory based at Cambridge, UK, in 1981 and as a part of this work, Fred Sanger, the received his second Nobel Prize. Several variations in the form of polymorphisms are observed from the Cambridge sequence in the mtDNA of different individuals.

Metabolic syndrome:

Metabolic syndrome is a cluster of conditions — increased blood pressure, a high blood sugar level, excess body fat around the waist or abnormal cholesterol levels — that occur together, increasing your risk of heart disease, stroke and diabetes. Metabolic syndrome is becoming more and more common in the United States. In the future, it may overtake smoking as the leading risk factor for heart disease. In general, a person who has metabolic syndrome is twice as likely to develop heart disease and five times as likely to develop diabetes as someone who doesn’t have metabolic syndrome.

The five conditions described below are metabolic risk factors. You must have at least three metabolic risk factors to be diagnosed with metabolic syndrome.

  • A large waistline. This also is called abdominal obesity or “having an apple shape.” Excess fat in the stomach area is a greater risk factor for heart disease than excess fat in other parts of the body, such as on the hips.
  • A high triglyceride level (or you’re on medicine to treat high triglycerides). Triglycerides are a type of fat found in the blood.
  • A low HDL cholesterol level (or you’re on medicine to treat low HDL cholesterol). HDL sometimes is called “good” cholesterol. This is because it helps remove cholesterol from your arteries. A low HDL cholesterol level raises your risk for heart disease.
  • High blood pressure (or you’re on medicine to treat high blood pressure). Blood pressure is the force of blood pushing against the walls of your arteries as your heart pumps blood. If this pressure rises and stays high over time, it can damage your heart and lead to plaque buildup.
  • High fasting blood sugar (or you’re on medicine to treat high blood sugar). Mildly high blood sugar may be an early sign of diabetes.

Role of Mitochondria in Metabolic Syndrome & Diabetes:

Impaired mitochondrial function has recently emerged as a potential causes of insulin resistance and/or diabetes progression, risk factors of metabolic syndrome.

Mitochondria plays several key functions including generation of ATP, and generating metabolites via Tricarboxylic acid cycle that function in cytosolic pathways, oxidative catabolism of amino acids, ketogenesis, urea cycle; the generation of reactive oxygen species (ROS); the control of cytoplasmic calcium; and the synthesis of all cellular Fe/S clusters, protein cofactors essential for cellular functions such as protein translation and DNA repair. These roles define the mitochondria to be involved in metabolic homeostasis and hence, a major candidate for metabolic syndrome and its associated risk factor including diabetes, obesity and insulin resistance.

Research and Therapeutic relevance:

Understanding the underlying molecular mechanism of aberrant role of mitochondria is important in developing therapeutic agents for mitochondria-associated diseases. In the recent issue of Mitonews, several papers have been published using the products of MitoSciences, which describe research pertaining to the importance of mitochondria in obesity and diabetes. Some recent research articles based on mitochondrial research (also mentioned in MitoNews) have been briefly discussed here:

  • Metabolic inflexibility and Metabolic syndrome: Metabolic inflexibility is defined as the failure of insulin-resistant patients to appropriately adjust mitochondrial fuel selection in response to nutritional cues. Although the phenomenon has been emphasized an important aspect of metabolic syndrome, the molecular mechanisms have not yet been fully deciphered. In a recent article by Muoio et al, published in Cell Metabolism journal, essential role of the mitochondrial matrix enzyme, carnitine acetyltransferase (CrAT) has been identified in regulating substrate switching and glucose tolerance. CrAT regulates mitochondrial and intracellular Carbon trafficking by converting acetyl-CoA to its membrane permeant acetylcarnitine ester. Using muscle muscle-specific Crat knockout mice, primary human skeletal myocytes, and human subjects undergoing L-carnitine supplementation, authors have suggested a model wherein CrAT combats nutrient stress, promotes metabolic flexibility, and enhances insulin action by permitting mitochondrial efflux of excess acetyl moieties that otherwise inhibit key regulatory enzymes such as pyruvate dehydrogenase. These findings offer therapeutically relevant insights into the molecular basis of metabolic inflexibility.
  • Rosiglitazone and obesity: Eepicardial adipose tissue (EAT) has been described in humans as a functioning brown adipose tissue (BAT) and has been shown in animal models to have a lower glucose oxidation rate and higher fatty acid (FA) metabolism. In obese individuals, epicardial adipose tissue (EAT) is “hypertrophied”. EAT is a source of BAT may be a source of proinflamatory cytokines. Distel et al published their studies using a rat model of obesity and insulin resistance treated with rosiglitazone. They observed that rosiglitazone, promoted a BAT phenotype in the EAT depot characterized by an increase in the expression levels of genes encoding proteins involved in mitochondrial processing and density PPARγ coactivator 1 alpha (PGC-1α), NADH dehydrogenase 1 and cytochrome oxidase (COX4) resulting in significant up-regulation of PGC1-α and COX4 protein. The authors concluded that PPAR-γ agonist could induce a rapid browning of the EAT that probably contributes to the increase in lipid turnover. Thus, important insights into the mechanism of fat metabolism and involvement of mitochondrial proteins with a therapy were presented in the article.
  • Mitochondrial dysfunction and diabetic neuropathy: Animal models of diabetic neuropathy show that mitochondrial dysfunction occurs in sensory neurons that may contribute to distal axonopathy. The adenosine monophosphate-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) signalling axis senses the metabolic demands of cells and regulates mitochondrial function. Studies in muscle, liver and cardiac tissues have shown that the activity of AMPK and PGC-1α is decreased under hyperglycaemia. Chowdhury et al using type 1 and type 2 diabetic rat and mice models studied the hypothesis that deficits in AMPK/PGC-1 signalling in sensory neurons underlie impaired axonal plasticity, suboptimal mitochondrial function and development of neuropathy. The authors have shown there is a significant reduction in phospho-AMPK, phopho-ACC, total PGC-1α, NDUFS3and COXIV in sensory neurons of the dorsal root ganglia of 14 week old diabetic mice with marked signs of thermal hypoalgesia. These results were associated with an impaired neuronal bioenergetic profile and a decrease in the activity of mitochondrial complex I, complex IV and citrate synthase. The fact that resveratrol treatment reversed the changes observed in vitro and in vivo suggest that the development of distal axonopathy in diabetic neuropathy is linked to nutrient excess and mitochondrial dysfunction via defective signalling of the AMPK/PGC-1α pathway.
  • ROS and diabetes: Mitochondria generated reactive oxygen species (ROS) has been associated with kidney damage occurring in diabetes. Rosca et al, published an article investigating the source and site of ROS production by kidney cortical tubule mitochondria in streptozotocin-induced type 1 diabetes in rats. The authors observed that in diabetic mitochondria, the fatty acid oxidation enzymes were elevated with increased oxidative phosphorylation and increased ROS production. The authors observed ROS production with fatty acid oxidation remained unchanged by limiting electron flow in ETC complexes, changes in ETC substrate processing and that the ROS supported by pyruvate also remained unaltered. The authors hence concluded that mitochondrial fatty acid oxidation is the source of increased ROS production in kidney cortical tubules in early diabetes

Sources:

http://www.ncbi.nlm.nih.gov/pubmed/11453081

http://health.cat/open.php?url=http://biochemgen.ucsd.edu/mmdc/ep-3-10.pdf

http://findarticles.com/p/articles/mi_go2827/is_n6_v27/ai_n28687375/

http://www.columbiamitodiagnostics.org/images/Mitobrochure.pdf

http://www.ncbi.nlm.nih.gov/pubmed?term=12372991

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0004546/

http://www.mayoclinic.com/health/metabolic%20syndrome/DS00522

http://www.nhlbi.nih.gov/health/health-topics/topics/ms/

http://www.ncbi.nlm.nih.gov/pubmed?term=22560225

http://www.ncbi.nlm.nih.gov/pubmed?term=%20%20%20%2022575275

http://www.ncbi.nlm.nih.gov/pubmed?term=%20%20%20%2022561641

http://www.mitosciences.com/mitonews_08_06.html

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