Potential Drug Combinations to Reduce Cardiovascular Disease Burden in Diabetes.

The major cause of death and complications in patients with type 2 diabetes (T2DM) is cardiovascular disease (CVD). More than 60% of all patients with T2DM die of CVD, and an even greater percentage have serious complications. The impact of glucose lowering on cardiovascular complications is a hotly debated issue and recent large clinical trials reported no significant decrease in cardiovascular events with intensive glucose control. Risk remains high even after correcting diabetes-associated dyslipidemia with drugs such as fibrates and niacin. Data from several clinical studies show that postprandial glucose and lipids have a strong predictive value on myocardial infarction (MI) and mortality. However, strategies to reduce postprandial hyperglycemia and/or lipemia through increased utilization of glucose and/or triglycerides (TG) have been shown to not be effective in reducing the CVD burden. In this review, I discus the preferred ways to reduce postprandial glucose and TG with combinations of currently marketed drugs with potential benefit in CVD.

Buprenorphine - an attractive opioid with underutilized potential in treatment of chronic pain.

Despite proven clinical utility, buprenorphine has not been used widely for the treatment of chronic pain. Questions about "ceiling effect" or bell-shaped curve observed for analgesia in preclinical studies and potential withdrawal issues on combining with marketed µ-agonists continue to hinder progress in expanding full potential of buprenorphine in the treatment of cancer and noncancer pain. Mounting evidence from clinical studies and conclusions drawn by a panel of experts strongly support superior safety and efficacy profile of buprenorphine vs marketed opioids. No ceiling on analgesic effect has been reported in clinical studies. The receptor pharmacology and pharmacokinetics profile of buprenorphine is complex but unique and contributes to its distinct safety and efficacy. The buprenorphine pharmacology also allows it to be combined with other µ-receptor opioids for additivity in efficacy. Transdermal delivery products of buprenorphine have been preferred choices for the management of pain but new delivery options are under investigation for the treatment of both opioid dependence and chronic pain.

A multimodal disease modifying approach to treat neuropathic pain--inhibition of soluble epoxide hydrolase (sEH).

Both neuronal and non-neuronal mechanisms have been proposed to contribute to neuropathic pain (NP). All currently approved treatments for NP modulate neuronal targets and provide only symptomatic relief. Here we review evidence that inhibition of soluble epoxide hydrolase (sEH), the enzyme that degrades epoxyeicosatrienoic acids (EETs), has potential to be a multimodal, disease modifying approach to treat NP: (1) EET actions involve both endogenous opioid system and the GABAergic systems thus provide superior pain relief compared to morphine or gabapentin, (2) EETs are directly anti-inflammatory and inhibit expression of inflammatory cytokines and adhesion molecules thus can prevent continued nerve damage; and (3) EETs promote nerve regeneration in cultured neurons. Thus, an sEH inhibitor will not only provide effective pain relief, but would also block further nerve damage and promote healing.

Heparan sulfate side chains have a critical role in the inhibitory effects of perlecan on vascular smooth muscle cell response to arterial injury.

Perlecan is a proteoglycan composed of a 470-kDa core protein linked to three heparan sulfate (HS) glycosaminoglycan chains. The intact proteoglycan inhibits the smooth muscle cell (SMC) response to vascular injury. Hspg2(Δ3/Δ3) (MΔ3/Δ3) mice produce a mutant perlecan lacking the HS side chains. The objective of this study was to determine differences between these two types of perlecan in modifying SMC activities to the arterial injury response, in order to define the specific role of the HS side chains. In vitro proliferative and migratory activities were compared in SMC isolated from MΔ3/Δ3 and wild-type mice. Proliferation of MΔ3/Δ3 SMC was 1.5× greater than in wild type (P < 0.001), increased by addition of growth factors, and showed a 42% greater migratory response than wild-type cells to PDGF-BB (P < 0.001). In MΔ3/Δ3 SMC adhesion to fibronectin, and collagen types I and IV was significantly greater than wild type. Addition of DRL-12582, an inducer of perlecan expression, decreased proliferation and migratory response to PDGF-BB stimulation in wild-type SMC compared with MΔ3/Δ3. In an in vivo carotid artery wire injury model, the medial thickness, medial area/lumen ratio, and macrophage infiltration were significantly increased in the MΔ3/Δ3 mice, indicating a prominent role of the HS side chain in limiting vascular injury response. Mutant perlecan that lacks HS side chains had a marked reduction in the inhibition of in vitro SMC function and the in vivo arterial response to injury, indicating the critical role of HS side chains in perlecan function in the vessel wall.

Thematic issue-topic--diabetic cardiovascular disease--an unmet medical need: emerging targets and therapies-introduction to the special issue.

The major cause of death and complications in patients with type 2 diabetes is cardiovascular disease. Cardiovascular complications that are often associated with diabetes include heart failure, acute myocardial infarction (MI), peripheral vascular disease, and cerebrovascular disease. More than 60% of all patients with type 2 diabetes die of cardiovascular disease, and an even greater percentage have serious complications. The impact of glucose lowering on cardiovascular complications is a hotly debated issue and recent large clinical trials, the Action in Diabetes and Vascular Disease (ADVANCE), Action to Control Cardiovascular Risk in Diabetes (ACCORD) and Veterans Affairs Diabetes Trial (VADT) reported no significant decrease in cardiovascular events with intensive glucose control. Risk remains high even after correcting diabetes-associated dyslipidemia (high triglycerides and low HDL). Several mechanisms are likely to contribute to the accelerated atherosclerosis and increased cardiovascular disease risk seen in type 2 diabetics. Of these, postprandial hyperglycemia/lipemia, insulin resistance and inflammation may be the most important and under controlled contributing factors to vascular disease. The goal of this thematic issue is to address limitations of current therapies and review emerging research and therapeutic approaches that target inflammation, insulin resistance and other pathological mechanisms that contribute to cardiovascular disease in diabetes.

Targeting soluble epoxide hydrolase for inflammation and pain - an overview of pharmacology and the inhibitors.

Chronic inflammation is an important contributing factor to a variety of human diseases including rheumatoid arthritis, inflammatory bowel disease, psoriasis and atherosclerosis. Epoxidation of arachidonic acid by cytochrome P450 enzymes during inflammation yields epoxyeicosatrienoic acids (EETs). EETs have a variety of biological effects including modulation of inflammation, vascular smooth muscle migration and platelet aggregation. The EETs levels are regulated by soluble epoxide hydrolase (sEH), the major enzyme responsible for their degradation and conversion to inactive dihydroxyeicosatrienoic acids (DHETs); thereby limiting many of the biological actions of EETs. The molecular and pharmacological inhibition of sEH has been studied extensively for benefits on the cardiovascular system. More recent studies suggest the importance of EETs and sEH in pain and inflammation. This review will discuss the current status and emerging evidence on the role of sEH and sEH inhibitors in chronic inflammatory conditions such as atherosclerosis, colitis and arthritis. Although steroids and non-steroidal anti-inflammatory drugs are effective, their chronic use is limited by the metabolic and cardiovascular side effects. Currently there are no small molecule drugs for treatment of chronic inflammation and associated pain and sEH inhibitors with their intrinsic cardiovascular protective effects can potentially fill this void.

Targeting interleukin-1ß for pain.

Interleukin-1ß (IL-1ß) has been implicated in many inflammatory and autoimmune diseases. Its role in pain, however, is under-appreciated. This may in part be due to the challenges involved in approaching the target from a therapeutic stand point. The scope of this brief review is to understand the direct and indirect roles of IL-1ß in contributing to different pain states including inflammatory and neuropathic pain, and discuss approaches to block IL-1ß production or IL-1ß-receptor interactions.

A perlecan-inducing compound significantly inhibits smooth muscle cell function and in-stent intimal hyperplasia: novel insights into the diverse biological effects of perlecan.

AIMS: Perlecan is the major heparan sulfate proteoglycan in the arterial wall. Previous studies have suggested that perlecan is a potent inhibitor of smooth muscle cell (SMC) activity. Therefore, perlecan overexpression may serve as a therapeutic modality to prevent in-stent restenosis (ISR). We have investigated a novel compound (RUS3108), identified in a SMC based screen to induce perlecan synthesis in SMC. The aims of this study were to assess the in vitro effects of RUS3108 and the effects of RUS3108-eluting stents in preventing ISR. METHODS AND RESULTS: Rabbit aortic SMC and bovine aortic endothelial cells (EC) were used in this study. Immunohistochemistry showed that RUS3108-treated SMC over-expressed perlecan indicating the drug effects. Furthermore, RUS3108 induced a SMC differentiated phenotype by SMembryonic staining. RUS3108 (1 microM) inhibited 3H-thymidine incorporation by >50%, which was completely reversed by a perlecan antibody. RUS3108 also inhibited SMC migration (Boyden chamber) and MMP-9 activity. In contrast, RUS3108 (100nM) modestly stimulated EC 3H-thymidine incorporation by 22% (p<0.02). In vivo, a total of 30 stents were deployed in rabbit iliac arteries as follows: 1) bare metal stents (n=10), 2) polymer onlycoated stents (n=10), and 3) polymer-coated stents containing RUS3108 (n=10). Rabbits were sacrificed at four weeks and stented segments were subjected to morphometric analysis. Intimal cross sectional area was significantly lower in the RUS3108-eluting stent group (0.31+ or -0.27 mm(2) versus 1.0 + or - 0.31 and 1.25 + or - 0.51 in the bare metal stents and polymer only coated stents groups, respectively, p<0.0001). CONCLUSIONS: RUS3108 is a novel perlecan-inducing compound, which is a potent inhibitor of SMC activity and a modest stimulator of EC proliferation. RUS3108-eluting stents may serve as an excellent modality for the prevention of ISR.

Pain and beyond: fatty acid amides and fatty acid amide hydrolase inhibitors in cardiovascular and metabolic diseases.

Fatty acid amide hydrolase (FAAH) is responsible for the hydrolysis of several important endogenous fatty acid amides (FAAs), including anandamide, oleoylethanolamide and palmitoylethanolamide. Because specific FAAs interact with cannabinoid and vanilloid receptors, they are often referred to as 'endocannabinoids' or 'endovanilloids'. Initial interest in this area, therefore, has focused on developing FAAH inhibitors to augment the actions of FAAs and reduce pain. However, recent literature has shown that these FAAs - through interactions with unique receptors (extracellular and intracellular) - can induce a diverse array of effects that include appetite suppression, modulation of lipid and glucose metabolism, vasodilation, cardiac function and inflammation. This review gives an overview of FAAs and diverse FAAH inhibitors and their potential therapeutic utility in pain and non-pain indications.

Lipoic acid synthase (LASY): a novel role in inflammation, mitochondrial function, and insulin resistance.

OBJECTIVE: Lipoic acid synthase (LASY) is the enzyme that is involved in the endogenous synthesis of lipoic acid, a potent mitochondrial antioxidant. The aim of this study was to study the role of LASY in type 2 diabetes. RESEARCH DESIGN AND METHODS: We studied expression of LASY in animal models of type 2 diabetes. We also looked at regulation of LASY in vitro under conditions that exist in diabetes. Additionally, we looked at effects of LASY knockdown on cellular antioxidant status, inflammation, mitochondrial function, and insulin-stimulated glucose uptake. RESULTS: LASY expression is significantly reduced in tissues from animal models of diabetes and obesity compared with age- and sex-matched controls. In vitro, LASY mRNA levels were decreased by the proinflammatory cytokine tumor necrosis factor (TNF)-alpha and high glucose. Downregulation of the LASY gene by RNA interference (RNAi) reduced endogenous levels of lipoic acid, and the activities of critical components of the antioxidant defense network, increasing oxidative stress. Treatment with exogenous lipoic acid compensated for some of these defects. RNAi-mediated downregulation of LASY induced a significant loss of mitochondrial membrane potential and decreased insulin-stimulated glucose uptake in skeletal muscle cells. In endothelial cells, downregulation of LASY aggravated the inflammatory response that manifested as an increase in both basal and TNF-alpha-induced expression of the proinflammatory cytokine, monocyte chemoattractant protein-1 (MCP-1). Overexpression of the LASY gene ameliorated the inflammatory response. CONCLUSIONS: Deficiency of LASY results in an overall disturbance in the antioxidant defense network, leading to increased inflammation, insulin resistance, and mitochondrial dysfunction.

A review of Sirt1 and Sirt1 modulators in cardiovascular and metabolic diseases.

Sirt1 (member of the sirtuin family) is a nicotinamide adenosine dinucleotide (NAD)-dependent deacetylase that removes acetyl groups from various proteins. A wide variety of proteins are Sirt1 substrates; the list includes many transcription factors and cofactors. Deacetylation of these factors may lead to activation or inactivation of the factor, thus impacting downstream gene expression. In addition to direct deacetylation, Sirt1 can modulate protein activity by other mechanisms. Although initial research focused on sirtuin's role in life span extension especially in lower organisms more recent studies show that Sirt1 activity can impact a wide array of proteins implicated in cardiovascular (CV) and metabolic diseases. Several patents have been published in the last 5 years describing the application of sirtuin compounds in the treatment of metabolic diseases. This review will focus on those Sirt1-modifiable proteins that have an impact on CV and metabolic diseases. Pharmacological agents that activate Sirt1 and thus impact the disease process will also be reviewed.

HDL elevators and mimetics--emerging therapies for atherosclerosis.

High plasma levels of LDL cholesterol, triglycerides and low levels of HDL cholesterol are strong and independent risk factors of coronary heart disease (CHD). The first two abnormalities are addressed by a variety of drugs including statins, cholesterol absorption inhibitors, fibrates and niacin. Some of these drugs also elevate HDL albeit weakly. Thus treatments optimized for HDL elevation are still an unmet medical need. Low HDL-C is the most common lipoprotein abnormality in patients with CHD and the body of evidence showing an inverse relationship between HDL-C levels and risk for CHD has grown large. Research in the past decade not only greatly enhanced our understanding of HDL metabolism but also offered potential therapeutic targets to address low HDL syndrome. There are two classes of these 'HDL drugs'--those that elevate plasma HDL (e.g. cholesteryl ester transfer protein--CETP and ligands of transcription factors such as peroxisome proliferator activated receptor PPARalpha/delta, liver X receptor (LXR)) and those that mimic HDL and facilitate reverse cholesterol transport (RCT) a key function of plasma HDL. HDL mimetics, which include ApoA1 mutants and peptide mimetics of ApoA1, are thought to be 'fast acting' and may show greater benefits especially in acute coronary syndromes. The purpose of this review is to examine key players in HDL metabolism and therapeutics that modulate/mimic these targets. The prospect of these approaches in the prevention of cardiovascular disease is also discussed.

Selected players in the inflammation cascade and drugs that target these inflammation genes against metastasis.

Despite many recent advances the prognosis of cancer patients with metastasis still remains poor. In metastatic invasion, tumor cells interact with endothelial cells through several distinct adhesion molecules. Adherent tumor cells extravasate into tissues by degrading basement membranes with matrix degrading enzymes such as heparanases and matrix metalloproteinases. Endothelial expression of matrix degrading enzymes and adhesion molecules are under the control of inflammatory cytokines. These inflammatory proteins and the signaling pathways involved in the expression of these genes are under intense investigation as therapeutic targets to prevent tumor growth and metastasis. The current review focuses on selected players of the inflammation cascade and drugs that target these inflammatory genes.

Emerging peptide therapeutics for inflammatory diseases.

Steroids are the best known anti-inflammatory drugs and have been in use for more than 50 years. Their chronic use however was limited by safety concerns. Non-steroidal anti-inflammatory drugs (NSAIDs) including COX-2 inhibitors although devoid of steroid side effects often possess gastrointestinal side effects. In addition recent data suggest that chronic use of some Cox inhibitors is associated with cardiovascular risk. Currently biologics represent the best option for many inflammatory diseases where TNFalpha is the main culprit. These include rheumatoid arthritis, ulcerative colitis, inflammatory bowel disease and psoriasis. A wealth of information is now available on the role of different cytokines and adhesion molecules in the origin and progression of inflammatory diseases. With the success of protein therapeutics such as Etanercept (Enbrel), which binds TNFalpha and inhibits its activity, research has been focused on developing small peptides that can interfere with cytokines or specific cell surface molecules and inhibit the inflammatory reactions. Here we review these peptides that are in discovery and development phases and their potential in the treatment of inflammatory diseases.

Vascular lipases, inflammation and atherosclerosis.

Members of the lipase family that include lipoprotein lipase, hepatic lipase and endothelial cell lipase play a central role in triglyceride and phospholipid hydrolysis. Because the site of action of these lipases is the endothelium, the endothelium is constantly exposed to products of lipolysis. These lipolysis products could elicit pro- or anti-inflammatory effects in endothelial as well as surrounding cells. These effects could be transient or long-term depending on the nutritional state. While lipolysis is per se anti-atherogenic due to its triglyceride lowering activity, it could also be pro-atherogenic due to prolonged exposure of endothelium to lipolysis products. In addition, lipoprotein lipase expressed in macrophages appears to be pro-atherogenic independent of plasma lipoproteins. In this review we summarize these pro- and anti-inflammatory consequences of lipolysis with respect to atherosclerosis.

Novel anti-inflammatory role for glycogen synthase kinase-3beta in the inhibition of tumor necrosis factor-alpha- and interleukin-1beta-induced inflammatory gene expression.

Glycogen synthase kinase-3beta (GSK-3beta) is a serine/threonine kinase with a broad array of cellular targets, such as cytoskeletal proteins and transcription factors. Recent studies with GSK-3beta-null mice showed impaired NFkappaB-mediated survival responses. Because NFkappaB serves a dual role as a key regulator of cytokine-induced inflammatory gene expression and apoptosis, we investigated whether modulation of GSK-3beta expression affects cytokine-induced and NFkappaB-mediated inflammatory gene expression. We observed that tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) treatment of primary cultures of human microvascular cells reduced net endogenous active GSK-3beta protein levels while inducing inflammatory cytokine (IL-6 and monocyte chemoattractant protein-1 (MCP-1)) expression. Interestingly, inhibition of GSK-3beta by antisense oligonucleotides or pharmacological agent (10 mm lithium) potentiated TNF-induced expression of IL-6 and MCP-1 by 2-6-fold suggesting that inhibition of GSK-3beta under inflammatory conditions (exposure to TNF-alpha and IL-1beta) may contribute to enhanced cytokine expression. Overexpression of GSK-3beta in endothelial cells, in contrast, significantly inhibited (by 70%, p < 0.01) both TNF-alpha and IL-1beta-induced expression of IL-6, MCP-1, and vascular cell adhesion molecule-1. Using adenoviruses in lipopolysaccharide-stimulated mice, overexpression of GSK-3beta significantly decreased TNF-alpha expression in lung and heart tissues (38 and 15%, respectively), further confirming the anti-inflammatory role of GSK-3beta. Overexpression of GSK-3beta did not affect the TNF-alpha-induced nuclear translocation of NFkappaB but reduced the nuclear half-life of TNF-alpha-induced NFkappaB considerably (by as much as 9 h) and enhanced phosphorylation (by as much as 33%). Interestingly, neither endothelial cell survival nor NFkappaB-mediated expression of anti-apoptotic genes was affected by GSK-3beta overexpression. We conclude that GSK-3beta selectively regulates NFkappaB-mediated inflammatory gene expression by controlling the flow of NFkappaB activity between transcription of inflammatory and survival genes.

Distinct effects of glucose and glucosamine on vascular endothelial and smooth muscle cells: evidence for a protective role for glucosamine in atherosclerosis.

Accelerated atherosclerosis is one of the major vascular complications of diabetes. Factors including hyperglycemia and hyperinsulinemia may contribute to accelerated vascular disease. Among the several mechanisms proposed to explain the link between hyperglycemia and vascular dysfunction is the hexosamine pathway, where glucose is converted to glucosamine. Although some animal experiments suggest that glucosamine may mediate insulin resistance, it is not clear whether glucosamine is the mediator of vascular complications associated with hyperglycemia. Several processes may contribute to diabetic atherosclerosis including decreased vascular heparin sulfate proteoglycans (HSPG), increased endothelial permeability and increased smooth muscle cell (SMC) proliferation. In this study, we determined the effects of glucose and glucosamine on endothelial cells and SMCs in vitro and on atherosclerosis in apoE null mice. Incubation of endothelial cells with glucosamine, but not glucose, significantly increased matrix HSPG (perlecan) containing heparin-like sequences. Increased HSPG in endothelial cells was associated with decreased protein transport across endothelial cell monolayers and decreased monocyte binding to subendothelial matrix. Glucose increased SMC proliferation, whereas glucosamine significantly inhibited SMC growth. The antiproliferative effect of glucosamine was mediated via induction of perlecan HSPG. We tested if glucosamine affects atherosclerosis development in apoE-null mice. Glucosamine significantly reduced the atherosclerotic lesion in aortic root. (P < 0.05) These data suggest that macrovascular disease associated with hyperglycemia is unlikely due to glucosamine. In fact, glucosamine by increasing HSPG showed atheroprotective effects.

Role of oxidative stress and inflammation in the origin of Type 2 diabetes--a paradigm shift.

In Type 2 diabetes the body either produces too little insulin, or does not respond well to it. Current pharmacological treatments, which are less than optimal, either target defective insulin secretion (sulfonylureas, glinides) or insulin resistance (metformin, thiazolidinediones). Exciting new research is now helping us to understand novel pathways that may contribute to defective insulin secretion as well as decreased response to insulin. Such pathways may explain the development of diabetes and associated complications (atherosclerosis and diabetic nephropathy). Understanding the way a cell metabolises glucose may be the key to understanding how cells secrete insulin and respond to it.