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)

Tangier disease (TD) is a human genetic disorder associated with defective apolipoprotein-I-induced lipid efflux and increased atherosclerotic susceptibility. It has been linked to mutations in the ATP-binding cassette protein A1 (ABCA1). Here we describe the establishment of permanent Tangier cell lines using telomerase. Ectopic expression of the catalytic subunit of human telomerase extended the life span of control and TD skin fibroblasts, and (in contrast to immortalization procedures using viral oncogenes) did not impair apolipoprotein A-I-induced lipid efflux. The key characteristics of TD fibroblasts (reduced cholesterol and phospholipid efflux) were observed both in primary and telomerase-immortalized fibroblasts from two unrelated homozygous patients. Surprisingly, the apolipoprotein-inducible cholesterol efflux in TD cells was significantly improved after immortalization (up to 40% of normal values). In contrast to ABCA1-dependent cholesterol efflux, this efflux was not inhibited by brefeldin A, glybenclamide, or intracellular ATP depletion but was inhibited in the presence of cytochalasin D. Apolipoprotein A-I-dependent cholesterol efflux was inversely correlated with the population doubling number in cell culture and was inhibited up to 40% in near-senescent normal diploid fibroblasts. This inhibition was completely reversed by telomerase. Thus ectopic expression of telomerase is a way to circumvent the lack of critical experimental material and represents a major improvement for studying cholesterol efflux pathways in lipid disorders. Our findings indicate the existence of an ABCA1-independent but cytoskeleton-dependent cholesterol removal pathway that may help to prevent early atherosclerosis in Tangier disease but may also be sensitive to aging phenomena ex vivo and possibly in vivo.
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PMID:The establishment of telomerase-immortalized Tangier disease cell lines indicates the existence of an apolipoprotein A-I-inducible but ABCA1-independent cholesterol efflux pathway. 1500 67

One of the American Heart Association's Top 10 Research Advances for the Treatment of Heart Disease is the use of a synthetic form of high-density lipoprotein (HDL) to reduce coronary atherosclerosis (JAMA. 2003;290:2292-2300). While HDL has not been a target for therapy for dyslipidemias, new insight into the major protein component of HDL, apolipoprotein A-I, may lead to new therapies. Apolipoprotein A-I was recently found to be a better predictor of cardiovascular events than is low-density lipoprotein (Am Heart J. 2003;146:227-233; J Intern Med. 2004;255:188-205). This article reviews the recent study by Nissen and colleagues describing the finding of a genetic mutation in HDL in some persons in Italy and the subsequent development of a synthetic form of HDL to be used as an infusion to successfully target atherosclerotic lesions (JAMA. 2003;290:2292-2300). In addition, controversies related to HDL cholesterol as a target for therapy are reviewed. Implications for nursing research, education, and practice are also described.
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PMID:A shot of good cholesterol: synthetic HDL, a new intervention for atherosclerosis. 1552 65

High-density lipoprotein (HDL)-cholesterol levels, inversely related to the risk of myocardial infarction, are determined by genetic and environmental factors. The aim of this study was to evaluate the prevalence of low and high HDL plasma levels and the influence of environmental factors and lipid profile in an Italian non-smoker female population. HDL, apolipoprotein A-I, apolipoproteins, lipids and estrogen plasma levels were measured in a population of 1471 women with a mean age of 45 +/- 14 years. HDL values < or = 35 mg/dl were noted in 11.2% of the subjects, showing 2.4% coronary heart disease (CHD) prevalence. The 90th percentile was characterized by HDL levels > or = 66 mg/dl and the absence of coronary atherosclerosis. Total cholesterol, apolipoprotein B and triglycerides (r = -0.31, p < 0.0001) were the main determinants of HDL levels; apolipoprotein E, estrogen use, body mass index (BMI), alcohol consumption and age showed a weaker correlation. Apolipoprotein A-I concentration was influenced more notably by estrogen use, total cholesterol and apolipoprotein E; levels of triglycerides, apolipoprotein B, BMI, age and alcohol consumption are less important. The parameters considered here, taken together, explain HDL and apolipoprotein A-I variability of approximately 31% and 24%, respectively. A surprisingly high prevalence of very low (< or = 35 mg/dl) and high (> or = 66 mg/dl) HDL levels in Italian women further confirms the importance of studies on the HDL distribution in different population groups.
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PMID:HDL and clinical and biochemical correlates in Italian non-smoker women. 1557 4

Diabetes mellitus is increasing worldwide, resulting from the interaction of obesity, inflammation, and hyperglycemia. Activated immunity and cytokine production lead to insulin resistance and other components of the metabolic syndrome, establishing the link between diabetes and atherosclerosis. Hyperglycemia-induced endothelial dysfunction is mediated by increased oxidative stress, a promoter of adventitial inflammation and vasa vasorum neovascularization in experimental models of diabetic atherosclerosis. Recent studies have documented increased inflammation, neovascularization, and intraplaque hemorrhage in human diabetic atherosclerosis. This inflammatory microangiopathic process is independently associated with plaque rupture, leading to coronary thrombosis. Tissue factor, the most potent trigger of the coagulation cascade, is increased in diabetic patients with poor glycemic control. Circulating tissue factor microparticles are also associated with apoptosis of plaque macrophages, closing the link among inflammation, plaque rupture, and blood thrombogenicity. High-density lipoproteins, responsible for free cholesterol removal, are reduced in patients with insulin resistance and diabetes. High-density lipoprotein therapy leads to a significant decrease in plaque macrophages and increase in smooth-muscle cells. These beneficial effects may be responsible for coronary plaque stabilization in patients treated with recombinant Apolipoprotein A-I Milano/phospholipid complex. Finally, peroxisomal proliferator-activated receptors (PPARs) are now considered the nuclear transcriptional regulators of atherosclerosis. Three subfamilies, including PPAR-alpha, -delta, and -gamma, have been identified with crucial roles in lipid metabolism, plaque inflammation, expression of adhesion molecules and cytokines, and regulation of matrix metalloproteinases. Multiple experimental studies have documented plaque stabilization with PPAR-gamma agonists, a group of medications holding great promise in the treatment of diabetes atherosclerosis.
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PMID:New aspects in the pathogenesis of diabetic atherothrombosis. 1560 89

In humans, a chronically increased circulating level of C-reactive protein (CRP), a positive acute-phase reactant, is an independent risk factor for cardiovascular disease. This observation has led to considerable interest in the role of inflammatory proteins in atherosclerosis. In this review, after discussing CRP, we focus on the potential role in the pathogenesis of human vascular disease of inflammation-induced proteins that are carried by lipoproteins. Serum amyloid A (SAA) is transported predominantly on HDL, and levels of this protein increase markedly during acute and chronic inflammation in both animals and humans. Increased SAA levels predict the risk of cardiovascular disease in humans. Recent animal studies support the proposal that SAA plays a role in atherogenesis. Evidence is accruing that secretory phospholipase A(2), an HDL-associated protein, and platelet-activating factor acetylhydrolase, a protein associated predominantly with LDL in humans and HDL in mice, might also play roles both as markers and mediators of human atherosclerosis. In contrast to positive acute-phase proteins, which increase in abundance during inflammation, negative acute-phase proteins have received less attention. Apolipoprotein A-I (apoA-I), the major apolipoprotein of HDL, decreases during inflammation. Recent studies also indicate that HDL is oxidized by myeloperoxidase in patients with established atherosclerosis. These alterations may limit the ability of apoA-I to participate in reverse cholesterol transport. Paraoxonase-1 (PON1), another HDL-associated protein, also decreases during inflammation. PON1 is atheroprotective in animal models of hypercholesterolemia. Controversy over its utility as a marker of human atherosclerosis may reflect the fact that enzyme activity rather than blood level (or genotype) is the major determinant of cardiovascular risk. Thus, multiple lipoprotein-associated proteins that change in concentration during acute and chronic inflammation may serve as markers of cardiovascular disease. In future studies, it will be important to determine whether these proteins play a causal role in atherogenesis.
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PMID:Thematic review series: The immune system and atherogenesis. Lipoprotein-associated inflammatory proteins: markers or mediators of cardiovascular disease? 1572 58

The lipid hypothesis, which was proposed over 100 years ago, is based on the premise that dyslipidemia is central to the process of atherosclerosis. Low-density lipoprotein and lipoprotein(a) are clearly atherogenic, whereas the role of very low-density lipoprotein as an independent factor is controversial. The only lipoprotein that is clearly antiatherogenic is high-density lipoprotein (HDL), which is thought to reduce coronary risk by mediating cholesterol efflux from the periphery by way of transportation to the liver for excretion. Traditionally, fibric acid derivatives and nicotinic acid were the major pharmacologic agents used to raise circulating levels of HDL. Recent therapeutic advances have been made in the ability to increase HDL. Apolipoprotein A-I Milano and cholesterol ester transfer protein represent novel approaches to the pharmacologic therapy of individuals with low HDL levels. The mechanisms and clinical implications of these interventions are discussed here.
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PMID:Raising high-density lipoprotein cholesterol: innovative strategies against an old adversary. 1572 22

Apolipoprotein A-I (apoA-I), the major protein in high density lipoprotein (HDL) regulates cholesterol homeostasis and is protective against atherosclerosis. An examination of the amino acid sequence of apoA-I among 21 species shows a high conservation of positively and negatively charged residues within helix 6, a domain responsible for regulating the rate of cholesterol esterification in plasma. These observations prompted an investigation to determine if charged residues in helix 6 maintain a structural conformation for protein-protein interaction with lecithin-cholesterol acyltransferase (LCAT) the enzyme for which apoA-I acts as a cofactor. Three apoA-I mutants were engineered; the first, (3)/(4) no negative apoA-I, eliminated 3 of the 4 negatively charged residues in helix 6, no negative apoA-I (NN apoA-I) eliminated all four negative charges, while all negative (AN apoA-I) doubled the negative charge. Reconstituted phospholipid-containing HDL (rHDL) of two discrete sizes and compositions were prepared and tested. Results showed that LCAT activation was largely influenced by both rHDL particle size and the net negative charge on helix 6. The 80 A diameter rHDL showed a 12-fold lower LCAT catalytic efficiency when compared to 96 A diameter rHDL, apparently resulting from an increased protein-protein interaction, at the expense of lipid-protein association on the 80 A rHDL. When mutant apoproteins were compared bound to the two different sized rHDL, a strong inverse correlation (r = 0.85) was found between LCAT catalytic efficiency and apoA-I helix 6 net negative charge. These results support the concept that highly conserved negatively charged residues in apoA-I helix 6 interact directly and attenuate LCAT activation, independent of the overall particle charge.
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PMID:Apolipoprotein A-I helix 6 negatively charged residues attenuate lecithin-cholesterol acyltransferase (LCAT) reactivity. 1580 34

Apolipoprotein A-I/C-III/A-IV (apoA-I/C-III/A-IV) SstI and apolipoprotein B (apoB) XbaI polymorphisms have been shown to affect serum low-density lipoprotein (LDL) cholesterol concentrations in a sample of Finnish children. We studied whether these polymorphism are associated with carotid artery intima-media thickness (IMT), a marker of pre-clinical atherosclerosis, measured in the same subjects during their adulthood. A random sub-sample of 214 individuals from the "Cardiovascular Risk in Young Finns" study, for whom genotypes, cardiovascular risk factor data and carotid artery IMT measured in 2001 were available, were studied. Mean carotid IMT values increased according to the apoA-I/C-III/A-IV SstI genotype groups in the order of S1S1 (0.58+/-0.08 mm), S1S2 (0.61+/-0.08 mm), and S2S2 (0.70+/-0.16 mm, p=0.02, ANOVA). In multiple linear regression analysis after adjusting for age, sex and body mass index the mean IMT thickness among the S2 allele carriers was higher (p=0.02) compared to non-carriers. In logistic regression analysis the frequency of S2 allele carriers was higher among the high IMT group compared to the low IMT group (OR=4.02, CI: 1.68-9.61, p=0.002). No significant association between apoB XbaI polymorphism and carotid IMT was found. However, serum total and LDL cholesterol and apoB concentrations were significantly different among apoB genotype groups (p<0.001 for all traits). The apoA-I/C-III/A-IV SstI polymorphism is associated with carotid IMT in young Finns.
Atherosclerosis 2005 May
PMID:Apolipoprotein A-I/C-III/A-IV SstI and apolipoprotein B XbaI polymorphisms and their association with carotid artery intima-media thickness in the Finnish population. The Cardiovascular Risk in Young Finns Study. 1582 78

The ATP-binding cassette transporter 1 (ABCA1) is a trans-membrane peptide that is involved in the lipidification of ApoA-I. ABCA1 gene was initially implicated in Tangier disease and familial hypoalphalipoproteinemia and has been shown to be associated with coronary artery disease and atherosclerosis as well. Recently, a haplotype in ABCA1 gene was associated with increased risk of type II diabetes mellitus (DM). In this report, a relationship between ApoA-I, DM and ABCA1 has been emphasized.
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PMID:ABCA1, ApoA-I and type II DM. 1600 32

An important issue in atherosclerosis is the timing of intimal microvascular formation and its relation to the initiation of plaque formation. Monocytes and endothelial cells (ECs) are important cell components in these steps. Statins not only reduce atherogenic low density lipoprotein cholesterol, they also increase high density lipoprotein-cholesterol (HDL). Although a higher concentration of statin has an anti-proliferative effect, HDL is potentially mitogenic. Therefore, we examined the opposing effects of statin, Apo-AI, HDL and HDL fractions on cell proliferation and apoptosis in monocytes and on angiogenesis in ECs. A high concentration of simvastatin inhibited monocyte proliferation as evaluated by counting cell numbers using a hematocytometer. This inhibition was mainly blocked by the HDL3 subfraction. The same concentration of simvastatin induced apoptosis as assessed by the fluorescence-labeled annexin-V method through caspase-3 activation in monocytes. HDL inhibited simvastatin-induced apoptosis. In addition, HDL blocked simvastatin-inhibited angiogenesis in an in vitro model of EC tube formation. In conclusion, the compensatory balance between the effects of statin and HDL may play an important role in the formation of atherosclerotic lesions by affecting proliferation and apoptosis in monocytes and angiogenesis in ECs.
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PMID:Counteracting effects of high density lipoprotein-cholesterol subfractions on statin-induced growth arrest. 1602 29


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