Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The peroxisome-proliferator-activated receptor gamma is a member of the nuclear receptor superfamily that functions as a key transcriptional regulator of cell differentiation and lipid metabolism. In addition, peroxisome-proliferator-activated receptor gamma is now recognized to be the biological receptor for the thiazolidinedione class of antidiabetic drugs, which includes troglitazone and rosiglitazone. Recent evidence indicates that peroxisome-proliferator-activated receptor gamma is expressed at high levels in macrophages, including the foam cells of atherosclerotic lesions. Oxidized low-density lipoprotein, which plays a central role in lesion development, can activate peroxisome-proliferator-activated receptor gamma by providing the cell with oxidized fatty acid ligands of the receptor. The elucidation of a peroxisome-proliferator-activated receptor gamma signalling pathway in macrophages provides a mechanism by which oxidized lipids may directly regulate gene expression in the context of the atherosclerotic lesions. A number of potential target genes for peroxisome-proliferator-activated receptor gamma in these cells have been identified. Some, such as the type B scavenger receptor CD36 are induced by peroxisome-proliferator-activated receptor gamma ligands, whereas others, such as scavenger receptor type A, inducible nitric oxide synthetase and certain cytokines, are repressed. Given the widespread clinical use of thiazolidinediones, it is important to consider the influence of these drugs on the risk of atherosclerosis. The net effect of peroxisome-proliferator-activated receptor gamma ligands on the atherogenic process is likely to reflect a balance between local effects in the artery wall and systemic effects on lipid metabolism.
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PMID:Regulation of macrophage gene expression by peroxisome-proliferator-activated receptor gamma: implications for cardiovascular disease. 1068 41

The use of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) in randomized clinical trials has established that cholesterol-lowering treatment reduces the risk of both cardiovascular and total mortality. This reduction in risk occurs in patients with or without existing cardiovascular disease and in patients with high or average plasma cholesterol concentrations. Aggressive treatment to lower plasma cholesterol has been shown to slow progression of atherosclerosis and in some instances may be as successful as angioplasty in reducing ischemic events. These studies suggest that reduction of plasma cholesterol to levels even below 100 mg/dl might be desirable. New targets for cholesterol-lowering therapy with mechanisms of action different from the statins have been identified. One of these targets is the Na(+)-dependent bile acid transporter that is expressed in the terminal ileum. This protein is responsible for recycling bile acids from the intestine to the liver. Several compounds that demonstrate the ability to decrease transporter activity and to lower plasma cholesterol have been investigated. Absorption of cholesterol from the small intestine is another potential target. Compounds that inhibit cholesterol absorption may act by interacting stoichiometrically with cholesterol within the intestinal lumen or substoichiometrically, presumably within the enterocyte. Finally, the transcriptional regulation of cholesterol 7alpha-hydroxylase by members of the nuclear receptor superfamily provides at least two other molecular targets for cholesterol-lowering drugs.
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PMID:New molecular targets for cholesterol-lowering therapy. 1077 97

Binding of agonists to nuclear receptors results in a conformational change in receptor structure that promotes interaction between activated receptors and coactivators. Receptor-coactivator interactions are mediated by the agonist-dependent formation of a hydrophobic pocket on the part of receptors, and short leucine-rich sequences termed LxxLL motifs or nuclear receptor boxes present in coactivators. RXR-PPARgamma (retinoid X receptor-peroxisome proliferator-activated receptor-gamma) heterodimers play important roles in adipocyte and macrophage differentiation and have been implicated as therapeutic targets in diabetes, atherosclerosis, and cancer. Analysis of interactions between RXR-PPARgamma heterodimers and coactivator nuclear receptor boxes suggests that RXR and PPARgamma can distinguish among coactivators by recognizing distinct structural features of nuclear receptor boxes. The results also indicate that coactivator choice by RXR is mediated by three nonconserved amino acids of the nuclear receptor box. The ability of an optimized seven-amino acid nuclear receptor box to specifically interact with RXR and function as a selective inhibitor suggests the coactivator-binding pocket may serve as a new target for drug discovery.
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PMID:Three amino acids specify coactivator choice by retinoid X receptors. 1093 44

The peroxisome proliferator-activated receptor gamma (PPARgamma) is a nuclear receptor that regulates fat-cell development and glucose homeostasis and is the molecular target of a class of insulin-sensitizing agents used for the management of type 2 diabetes mellitus. PPARgamma is highly expressed in macrophage foam cells of atherosclerotic lesions and has been demonstrated in cultured macrophages to both positively and negatively regulate genes implicated in the development of atherosclerosis. We report here that the PPARgamma-specific agonists rosiglitazone and GW7845 strongly inhibited the development of atherosclerosis in LDL receptor-deficient male mice, despite increased expression of the CD36 scavenger receptor in the arterial wall. The antiatherogenic effect in male mice was correlated with improved insulin sensitivity and decreased tissue expression of TNF-alpha and gelatinase B, indicating both systemic and local actions of PPARgamma. These findings suggest that PPARgamma agonists may exert antiatherogenic effects in diabetic patients and provide impetus for efforts to develop PPARgamma ligands that separate proatherogenic activities from antidiabetic and antiatherogenic activities.
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PMID:Peroxisome proliferator-activated receptor gamma ligands inhibit development of atherosclerosis in LDL receptor-deficient mice. 1097 14

A progressive rise of oxidative stress due to the altered redox homeostasis appears to be one of the hallmarks of the aging process. Reactive oxygen species (ROS) also serve as signaling agents for inflammation, a systemic defensive reaction against microbial pathogens and other foreign bodies. Changes in the pattern of gene expression through ROS-sensitive transcription factors give rise to both aging and inflammation phenotypes. Chronic oxidative stress and inflammatory reaction also lead to many age-associated diseases such as atherosclerosis and arthritis. Transcription factors that are directly influenced by ROS and proinflammatory cytokines include nuclear factor kappa B (NF-kappaB), activator protein 1 (AP-1), specificity protein 1 (Sp1), peroxisome proliferator-activated receptors (PPARs) and other members of the nuclear receptor superfamily. Here we describe the basic components of the intracellular redox control machinery and their dysregulation with age leading to altered transcription factor function and age-associated pathophysiology.
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PMID:Role of redox-regulated transcription factors in inflammation, aging and age-related diseases. 1097 75

Chronic inflammation is a hallmark of degenerative diseases such as atherosclerosis. Peroxisome proliferator-activated receptors (PPARs) are transcription factors belonging to the nuclear receptor superfamily, which are expressed in the cells of the atherosclerosic lesion. PPARalpha ligands have been reported to exert anti-inflammatory activities in different cell types by antagonizing the transcriptional activity of NF-kappaB. In the present study, the influence of PPARalpha activators on the NF-kappaB signaling pathway was investigated. Our results show that fibrates, synthetic PPARalpha activators, induced the expression of the inhibitory protein IkappaBalpha in human aortic smooth muscle cells as well as in primary human hepatocytes, whereas neither IkappaB-kinase activity nor the degradation rate of IkappaBalpha were affected. Using PPARalpha-null mice, we demonstrated that fibrates induced IkappaBalpha in liver in vivo and that this action required PPARalpha. Furthermore, fibrate treatment induced IkappaBalpha protein expression in the cytoplasm and also enhanced IL-1beta-induced accumulation of IkappaBalpha protein in the nucleus. These actions of fibrates on IkappaBalpha expression were accompanied by a decrease in NF-kappaB DNA binding activity as demonstrated by electrophoretic mobility shift assays. Taken together, these data provide an additional molecular mechanism for the anti-inflammatory activity of PPARalpha agonists and reinforce their potential use in the treatment of inflammatory diseases.
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PMID:Induction of IkappaBalpha expression as a mechanism contributing to the anti-inflammatory activities of peroxisome proliferator-activated receptor-alpha activators. 1098 Jan 95

The CCR2-mediated recruitment of monocytes into the vessel wall plays an important role in all stages of atherosclerosis. In recent studies, we have shown that lipoproteins can modulate CCR2 expression and have identified native LDL as a positive regulator. In contrast, oxidized LDL (OxLDL), which is mainly formed in the aortic intima, reduces CCR2 expression, promotes monocyte retention, and may cause pathological accumulation of monocytes in the vessel wall. We now provide evidence that OxLDL reduces monocyte CCR2 expression by activating intracellular signaling pathways that may involve peroxisome proliferator-activated receptor gamma (PPARgamma). Receptor-mediated uptake of the lipoprotein particle was required and allows for delivery of the exogenous ligand to the nuclear receptor. The suppression of CCR2 expression by OxLDL was mediated by lipid components of OxLDL, such as the oxidized linoleic acid metabolites 9-HODE and 13-HODE, known activators of PPARgamma. Modified apoB had no such effect. Consistent with a participation of the PPARgamma signaling pathway, BRL49653 reduced CCR2 expression in freshly isolated human monocytes ex vivo and in circulating mouse monocytes in vivo. These results implicate PPARgamma in the inhibition of CCR2 gene expression by oxidized lipids, which may help retain monocytes at sites of inflammation, such as the atherosclerotic lesion.
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PMID:Oxidized LDL reduces monocyte CCR2 expression through pathways involving peroxisome proliferator-activated receptor gamma. 1099 90

Peroxisome proliferator-activated receptors (PPAR) are ligand-activated transcription factors which form a subfamily of the nuclear receptor gene family. PPAR activators have effects on both metabolic risk factors and on vascular inflammation related to atherosclerosis. PPAR have profound effects on the metabolism of lipoproteins and fatty acids. PPAR alpha binds hypolipidemic fibrates, whereas PPAR gamma has a high affinity for antidiabetic glitazones. Both PPAR are activated by fatty acids and their derivatives. Activation of PPAR alpha increases the catabolism of fatty acids at several levels. In the liver, it increases uptake of fatty acids and activates their beta-oxidation. The effects that PPAR alpha exerts on triglyceride-rich lipoproteins is due to their stimulation of lipoprotein lipase and repression of apolipoprotein CIII expression, while the effects on high-density lipoproteins depend upon the regulation of apolipoproteins AI and AII. PPAR gamma has profound effects on the differentiation and function of adipose tissue, where it is highly expressed. PPAR are also expressed in atherosclerotic lesions. PPAR are present in vascular endothelial cells, smooth muscle cells, monocytes, and monocyte-derived macrophages. Via negative regulation of nuclear factor-kappa B and activator protein-1 signalling pathways, PPAR alpha inhibits expression of inflammatory genes, such as interleukin-6, cyclooxygenase-2, and endothelin-1. Furthermore, PPAR alpha inhibits expression of monocyte-recruiting proteins such as vascular cell adhesion molecule (VCAM)-1 and induces apoptosis in monocyte-derived macrophages. PPAR gamma activation in macrophages and foam cells inhibits the expression of activated genes such as inducible nitric oxide synthase, matrix metalloproteinase-9 and scavenger receptor A. PPAR gamma may also affect the recruitment of monocytes in atherosclerotic lesions as it is involved in the expression of VCAM-1 and intracellular adhesion molecule-1 in vascular endothelial cells. The involvement of PPAR in atherosclerosis, a disease with a chronic inflammatory character, suggests that they may play a role in other inflammatory-related diseases as well.
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PMID:Role of the peroxisome proliferator-activated receptors (PPAR) in atherosclerosis. 1100 63

Clinical studies have suggested that hormone replacement therapy (HRT) may reduce the risk of coronary heart disease in postmenopausal women. Although progestins are commonly added to HRT preparations for uteroprotection, the perceived beneficial cardiovascular effects of HRT are thought to be mediated predominantly by the estrogen component. Platelets play a critical role in the pathogenesis of atherosclerosis and cardiovascular disease and, hence, it is possible that the cardiovascular effects of estrogens are mediated, at least in part, through inhibition of illicit platelet activation. The aim of this study was to examine the effects of sex steroids on adenosine diphosphate (ADP)-induced platelet aggregation and adenosine triphosphate (ATP) release in vitro in postmenopausal women. In addition, the effects of antiestrogens 14-hydroxy tamoxifen (4-OHT) and ICI 182780] and antiprogestins (RU 486 and ZK 98299) were also investigated. Preincubation of platelet-rich plasma (PRP) with antiestrogens or antiprogestins did not alter subsequent platelet aggregation or ATP release in response to ADP. However, preincubation with 17beta-estradiol (E2) significantly inhibited ADP-mediated platelet aggregation by a mean (+/-SEM) of 37%+/-6% (p = 0.02) and ATP release by 82%+/-6% (p = 0.03), an effect that was reversed by the addition of ICI 182780 or 4-OHT but not RU 486 and ZK 98299. Although the progestin medroxyprogesterone acetate (MPA) also significantly inhibited platelet aggregation (by 28%+/-5%, p = 0.02) and ATP release (by 63%+/-9%, p = 0.02), this inhibition was not reversed by the addition of antiprogestins or antiestrogens. These data show that sex steroids can modulate platelet function in vitro. Furthermore, as platelets are devoid of nuclear components, these findings indicate that estrogens may regulate platelet function through binding to a non-nuclear receptor with ligand-binding properties similar or identical to the wild-type receptor. By contrast, MPA appears to exert its effect through a mechanism that does not involve binding to the "classical" progesterone receptor.
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PMID:Regulation of platelet aggregation and adenosine triphosphate release in vitro by 17beta-estradiol and medroxyprogesterone acetate in postmenopausal women. 1105 72

Peroxisome proliferator-activated (PPARs) are ligand-activated transcription factors belonging to the nuclear receptor family. PPARs function as regulators of lipid and lipoprotein metabolism and glucose homeostasis and influence cellular proliferation, differentiation and apoptosis. PPARalpha is highly expressed in tissues such as liver, muscle, kidney and heart, where it stimulates the beta-oxidative degradation of fatty acids. PPARgamma is predominantly expressed in intestine and adipose tissue. PPARgamma triggers adipocyte differentiation and promotes lipid storage. The hypolipidemic fibrates and the antidiabetic glitazones are synthetic ligands for PPARalpha and PPARgamma, respectively. Furthermore, fatty acids and eicosanoids are natural PPAR ligands: PPARalpha is activated by leukotriene B4, whereas prostaglandin J2 is a PPARgamma ligand. These observations suggested a potential role for PPARs not only in metabolic but also in inflammation control. The first evidence for a role of PPARalpha in inflammation control came from the demonstration that PPARalpha deficient mice display a prolonged response to inflammatory stimuli. It was suggested that PPARalpha deficiency results in a reduced beta-oxidative degradation of these inflammatory fatty acid derivatives. More recently, PPAR activators were shown to inhibit the activation of inflammatory response genes (such as IL-2, IL-6, IL-8, TNFalpha and metalloproteases) by negatively interfering with the NF- kappaB, STAT and AP-1 signalling pathways. PPAR activators exert these anti-inflammatory activities in different immunological and vascular wall cell types such as monocyte/macrophages, endothelial, epithelial and smooth muscle cells in which PPARs are expressed. These recent findings indicate a modulatory role for PPARs in the control of the inflammatory response with potential therapeutic applications in inflammation-related diseases, such as atherosclerosis and inflammatory bowel disease.
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PMID:Peroxisome proliferator-activated receptors (PPARs): nuclear receptors at the crossroads between lipid metabolism and inflammation. 1108


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