Dyslipidemia and the vulnerable plaque

The relationship between the atherogenic index of plasma and postoperative myocardial injury following non-cardiac surgery under general anaesthesia: a retrospective cohort study

BACKGROUND

The atherogenic index of plasma (AIP) is a reliable lipid marker associated with coronary artery stenosis (CAS) and cardiovascular events. However, the relationship between AIP and myocardial injury after non-cardiac surgery (MINS) remains insufficiently explored.

METHODS

This retrospective study included adult patients who underwent non-cardiac surgery under general anaesthesia. The primary exposure was preoperative AIP, with MINS as the primary outcome. The predictive accuracy of AIP for MINS was assessed using the area under the curve (AUC). Restricted cubic splines (RCS) were used to explore the potential nonlinear relationship between AIP and MINS. Logistic regression analysis was conducted to examine the association of AIP with MINS. Subgroup and interaction analyses were carried out across multiple factors, including age, gender, body mass index, medical history, and the type of surgery (emergency or elective).

RESULTS

The cohort consisted of 1,160 adult patients, with a median preoperative AIP of -0.05. The incidence of MINS was 7.9%. The AUC for AIP in predicting MINS was 0.719, surpassing the AUCs of triglycerides and high-density lipoprotein cholesterol (0.644 and 0.683, respectively). RCS analysis demonstrated a linear relationship between AIP and MINS (P for nonlinear = 0.165). Patients in the highest quartile of AIP had significantly higher odds of developing MINS than those in the lowest quartile (adjusted OR, 8.05; 95% confidence interval [CI], 3.44 to 18.80; P < 0.001). The results across most subgroups were consistent with the primary analysis, showing no significant interaction effects.

CONCLUSIONS

A significant and independent linear relationship exists between preoperative AIP and the risk of MINS. As an economical and easily accessible lipid marker, AIP holds potential for preoperative screening of patients at risk of postoperative cardiovascular events.

Stenting versus medical treatment alone for symptomatic intracranial artery stenosis: a preplanned pooled individual patient data analysis

BACKGROUND

Whether the safety and efficacy of percutaneous transluminal angioplasty and stenting (PTAS) is significantly different from that of medical treatment alone for symptomatic intracranial arterial stenosis (ICAS) is debatable. A study was undertaken to determine the safety and efficacy of both treatments for symptomatic ICAS.

METHODS

This preplanned pooled individual patient data analysis included 400 participants treated with PTAS and 409 treated with medical treatment alone in two large multicenter randomized clinical trials (SAMMPRIS and CASSISS). Patients were treated with PTAS using a self-expanding stent or medical treatment alone. The primary outcome was stroke or death within 30 days, or ischemic stroke in the territory of the qualifying artery more than 30 days after enrollment.

RESULTS

Individual data were obtained for 809 patients, 451 from SAMMPRIS and 358 from CASSISS. 400 participants were randomly assigned to the PTAS group and 409 to the medical group. The risk of the primary outcome was not significant between the PTAS and medical groups (17.5% vs 13.2%; HR 1.37 (95% CI 0.96 to 1.95), P=0.08). However, the risk of stroke or death within 30 days was higher in the PTAS group (10.5% vs 4.2%; HR 2.62 (95% CI 1.49 to 4.61), P<0.001). Patients of white ethnicity (HR 1.97, 95% CI 1.17 to 3.31) and those with hyperlipidemia (HR 2.04, 95% CI 1.27 to 3.26) or a transient ischemic attack (TIA) (HR 2.19, 95% CI 1.08 to 4.45) were at higher risk for PTAS.

CONCLUSIONS

PTAS poses an increased risk of short-term stroke/death and therefore is not advised as primary treatment for symptomatic ICAS. A balance exists between stroke risks and revascularization benefits. For patients with asymptomatic ICAS of white ethnicity and those with hyperlipidemia or a history of TIA, a thorough assessment is warranted before considering PTAS.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00576693, NCT01763320.

Relationship between stressful life events and coronary plaque vulnerability among patients with acute coronary syndrome: a moderated mediation model of psychological distress and physiological indices

We aimed to explore the association between stressful life events and coronary plaque vulnerability, and examine the moderating effects of psychological distress and physiological indices. A total of 311 patients with acute coronary syndrome (ACS) completed Life Events Scale, Zung Self-Rating Depression and Anxiety Scales. Plaque vulnerability was assessed by in vivo optical coherence tomography (OCT). The regression analysis showed that that stressful life events were independent predictors of plaque vulnerability including lipid-rich plaque (OR = 1.018, 95% CI = 1.005, 1.031, p = 0.005), thin-cap fibroatheroma (TCFA) (OR = 1.038, 95% CI = 1.025, 1.051, p < 0.001), rupture (OR = 1.025, 95% CI = 1.013, 1.037, p < 0.001) and thrombus (OR = 1.030, 95% CI = 1.012, 1.048, p = 0.001). The moderated mediation model revealed that there were significant indirect effects of stressful life events on TCFA through total cholesterol, and the path between stressful life events and TCFA can be moderated by depression. Stressful life events increase the risk of vulnerable plaque in ACS patients. The relationship could be moderated by depression and mediated by physiological indices.

Atherogenic Index of Plasma, Triglyceride-Glucose Index and Monocyte-to-Lymphocyte Ratio for Predicting Subclinical Coronary Artery Disease

BACKGROUND

The atherogenic index of plasma (AIP), triglyceride-glucose (TyG) index, and monocyte-to-lymphocyte ratio (MLR) are strongly associated with atherogenesis of the coronary artery. This study aimed to investigate the association of the AIP, TyG index, and MLR with subclinical coronary artery disease (CAD) and evaluate their ability to predict subclinical CAD.

METHODS

A total of 697 asymptomatic patients were enrolled in this study and assigned to the subclinical CAD group (n=332) and control group (n=365). The clinical data, coronary artery calcification score, and calculated AIP, TyG index, and MLR were collected by graduate students in the cardiology division. Multivariate logistic regression models were set up to assess the risk factors for subclinical CAD.

RESULTS

The AIP, TyG index and MLR values were higher in the subclinical CAD group than in the control group (all P<0.05). In addition to the classic independent clinical risk factors, increased AIP, TyG index and MLR values were all independent risk factors for subclinical CAD (all P<0.05). The AUCs were higher after combining clinical risk factors than the AIP, TyG index, or MLR alone (all P<0.05).

CONCLUSIONS

The AIP, TyG index and MLR are independent risk factors for subclinical CAD, which can be useful for improving the diagnosis and prevention of CAD.

Nanoparticle-based "Two-pronged" approach to regress atherosclerosis by simultaneous modulation of cholesterol influx and efflux

Reduction of lipoprotein uptake by macrophages and stimulation of cholesterol efflux are two essential steps required for atherosclerotic plaque regression. We used the optimized mannose-functionalized dendrimeric nanoparticle (mDNP)-based platform for macrophage-specific delivery of therapeutics to simultaneously deliver SR-A siRNA (to reduce LDL uptake) and LXR ligand (LXR-L, to stimulate cholesterol efflux) - a novel "Two-pronged" approach to facilitate plaque regression. mDNP-mediated delivery of SR-A siRNA led to a significant reduction in SR-A expression with a corresponding decrease in uptake of oxLDL. Delivery of LXR-L increased expression of ABCA1/G1 and cholesterol efflux. Combined delivery of siRNA and LXR-L led to a significantly greater decrease in macrophage cholesterol content compared to either treatment alone. Administration of this in vitro optimized formulation of mDNP complexed with SR-A-siRNA and LXR-L (Two-pronged complex) to atherosclerotic LDLR-/- mice fed western diet (TD88137) led to significant regression of atherosclerotic plaques with a corresponding decrease in aortic cholesterol content.

The Goal of Achieving Atherosclerotic Plaque Regression with Lipid-Lowering Therapy: Insights from IVUS Trials

Enormous effort has been put into the prevention of atherosclerosis through risk modification, especially with lipid-lowering therapies. Regression, that is, the reversal of the atherosclerosis process, has long been a goal of atherosclerosis research among basic and clinical investigators. Intravascular ultrasound (IVUS) was developed in the 1990s as an intracoronary imaging technique to observe the details of the vessel walls and to measure the vessel lumen and plaque area with high reproducibility. Compared with the coronary angiogram, IVUS provides far more detailed information on the vessel wall. In this article, we review lipid-lowering trials that have used IVUS and discuss the current understanding of the effectiveness of aggressive lipid-lowering therapy, which inhibits atherosclerotic progression and induces regression and plaque stabilization.

Insights From Pre-Clinical and Clinical Studies on the Role of Innate Inflammation in Atherosclerosis Regression

Atherosclerosis, the underlying cause of coronary artery (CAD) and other cardiovascular diseases, is initiated by macrophage-mediated immune responses to lipoprotein and cholesterol accumulation in artery walls, which result in the formation of plaques. Unlike at other sites of inflammation, the immune response becomes maladaptive and inflammation fails to resolve. The most common treatment for reducing the risk from atherosclerosis is low density lipoprotein cholesterol (LDL-C) lowering. Studies have shown, however, that while significant lowering of LDL-C reduces the risk of heart attacks to some degree, there is still residual risk for the majority of the population. We and others have observed “residual inflammatory risk” of atherosclerosis after plasma cholesterol lowering in pre-clinical studies, and that this phenomenon is clinically relevant has been dramatically reinforced by the recent Canakinumab Anti-inflammatory Thrombosis Outcomes Study (CANTOS) trial. This review will summarize the role of the innate immune system, specifically macrophages, in atherosclerosis progression and regression, as well as the pre-clinical and clinical models that have provided significant insights into molecular pathways involved in the resolution of plaque inflammation and plaque regression. Partnered with clinical studies that can be envisioned in the post-CANTOS period, including progress in developing targeted plaque therapies, we expect that pre-clinical studies advancing on the path summarized in this review, already revealing key mechanisms, will continue to be essential contributors to achieve the goals of dampening plaque inflammation and inducing its resolution in order to maximize the therapeutic benefits of conventional risk factor modifications, such as LDL-C lowering.

The role of HDL in plaque stabilization and regression: basic mechanisms and clinical implications

On the basis of studies that extend back to the early 1900s, regression and stabilization of atherosclerosis in humans has progressed from being a concept to one that is achievable. Successful attempts at regression generally applied robust measures to improve plasma lipoprotein profiles. Possible mechanisms responsible for lesion shrinkage include decreased retention of atherogenic apolipoprotein B within the arterial wall, efflux of cholesterol and other toxic lipids from plaques, emigration of lesional foam cells out of the arterial wall, and influx of healthy phagocytes that remove necrotic debris as well as other components of the plaque. Currently available clinical agents, however, still fail to stop most cardiovascular events. For years, HDL has been considered the 'good cholesterol.' Clinical intervention studies to causally link plasma HDL-C levels to decreased progression or to the regression of atherosclerotic plaques are relatively few because of the lack of therapeutic agents that can selectively and potently increase HDL-C. The negative results of studies that were carried out have led to uncertainty as to the role that HDL plays in atherosclerosis. It is becoming clearer, however, that HDL function rather than quantity is most crucial and, therefore, discovery of agents that enhance the quality of HDL should be the goal.

The phenomenon of atherosclerosis reversal and regression: Lessons from animal models

Studies in non-rodent and murine models showed that atherosclerosis can be reversed. Atherosclerosis progression induced by high-fat or cholesterol-rich diet can be reduced and reversed to plaque regression after switching to a normal diet or through administration of lipid-lowering agents. The similar process should exist in humans after implementation of lipid-lowering therapy and as a result of targeting of small rupture-prone plaques that are major contributors for acute atherosclerotic complications. Lowering of low density lipoprotein (LDL) cholesterol and the activation of reverse cholesterol transport lead to a decline in foam cell content, to the depletion of plaque lipid reservoirs, a decrease in lesional macrophage numbers through the activation of macrophage emigration and, probably, apoptosis, dampening plaque inflammation, and the induction of anti-inflammatory macrophages involved in clearance of the necrotic core and plaque healing. By contrast, plaque regression is characterized by opposite events, leading to the retention of atherogenic LDL and oxidized LDL particles in the plaque, an increased flux of monocytes, the immobilization of macrophages in the intimal vascular tissues, and the propagation of intraplaque inflammation. Transfer of various apolipoprotein (apo) genes to spontaneously hypercholesterolemic mice deficient for either apoE or LDL receptor and, especially, the implementation of the transplantation murine model allowed studying molecular mechanisms of atherosclerotic regression, associated with the depletion of atherogenic lipids in the plaque, egress of macrophages and phenotypic switch of macrophages from the proinflammatory M1 to the anti-inflammatory M2.

Targeted Knockdown of Hepatic SOAT2 With Antisense Oligonucleotides Stabilizes Atherosclerotic Plaque in ApoB100-only LDLr-/- Mice

OBJECTIVE

To test the hypothesis that the attenuation of cholesterol oleate packaging into apoB-containing lipoproteins will arrest progression of pre-existing atherosclerotic lesions.

APPROACH AND RESULTS

Atherosclerosis was induced in apoB-100 only, LDLr(-/-) mice by feeding a diet enriched in cis-monounsaturated fatty acids for 24 weeks. A subset of mice was then euthanized to quantify the extent of atherosclerosis. The remaining mice were continued on the same diet (controls) or assigned to the following treatments for 16 weeks: (1) a diet enriched in n-3 polyunsaturated fatty acids, (2) the cis-monounsaturated fatty acid diet plus biweekly injections of an antisense oligonucleotide specific to hepatic sterol-O-acyltransferase 2 (SOAT2); or (3) the cis-monounsaturated fatty acid diet and biweekly injections of a nontargeting hepatic antisense oligonucleotide. Extent of atherosclerotic lesions in the aorta was monitored morphometrically in vivo with magnetic resonance imaging and ex vivo histologically and immunochemically. Hepatic knockdown of SOAT2 via antisense oligonucleotide treatment arrested lesion growth and stabilized lesions.

CONCLUSIONS

Hepatic knockdown of SOAT2 in apoB100-only, LDLr(-/-) mice resulted in remodeling of aortic atherosclerotic lesions into a stable phenotype, suggesting SOAT2 is a viable target for the treatment of atherosclerosis.

Regression of atherosclerosis: insights from animal and clinical studies

BACKGROUND

Based on studies that date back to the 1920s, regression and stabilization of atherosclerosis in humans has gone from just a dream to one that is achievable. Review of the literature indicates that the successful attempts at regression generally applied robust measures to improve plasma lipoprotein profiles. Examples include extensive lowering of plasma concentrations of atherogenic apolipoprotein B and enhancement of reverse cholesterol transport from atheromata to the liver.

FINDINGS

Possible mechanisms responsible for lesion shrinkage include decreased retention of atherogenic apolipoprotein B within the arterial wall, efflux of cholesterol and other toxic lipids from plaques, emigration of lesional foam cells out of the arterial wall, and influx of healthy phagocytes that remove necrotic debris as well as other components of the plaque. This review will highlight the role key players such as LXR, HDL and CCR7 have in mediating regression.

CONCLUSION

Although much progress has been made, there are many unanswered questions. There is, therefore, a clear need for preclinical and clinical testing of new agents expected to facilitate atherosclerosis regression with the hope that additional mechanistic insights will allow further progress.

Novel pharmacotherapies of familial hyperlipidemia

Familial hyperlipidemia is an inherited metabolic disorder characterized by elevated lipid and/or lipoprotein levels in the blood. Despite improvements in lipid-lowering therapy during the last decades, it still remains a substantial contributor to the incidence of cardiovascular disease since patients on current conventional therapies do not achieve their target LDL-cholesterol levels. With a view to lower LDL-cholesterol levels, a number of new therapeutic strategies have been developed over recent years. In this review, we provide an overview of these treatment options that are currently in clinical development and may offer alternative or adjunctive therapies for this high-risk population.

Astaxanthin prevents changes in the activities of thioredoxin reductase and paraoxonase in hypercholesterolemic rabbits

This study explored the effects of the antioxidant astaxanthin on paraoxonase and thioredoxin reductase activities as well as on other oxidative stress parameters and on the lipid profile in hypercholesterolemic rabbits. Rabbits were fed a standard or a hypercholesterolemic diet alone or supplemented with 50, 100 and 500 mg/100 g of astaxanthin for 60 days. Antioxidant enzymes activities, lipid profile and oxidative stress markers were evaluated in the serum. The hypercholesterolemic diet increased lipids, including unsaturated fatty acids level, whereas it decreased saturated fatty acids level. These changes were accompanied by increased levels of oxidized low-density lipoprotein and oxidized low-density lipoprotein antibodies, as well as lipid and protein oxidation. Astaxanthin (100 and 500 mg/100 g) prevented hypercholesterolemia-induced protein oxidation, whereas 500 mg/100 g of astaxanthin decreased protein oxidation per se. The activities of superoxide dismutase and thioredoxin reductase were enhanced, whereas paraoxonase activity was inhibited in hypercholesterolemic rabbits. All astaxanthin doses prevented changes in thioredoxin reductase and paraoxonase activities. This effect was not related to a direct effect of astaxanthin on these enzymes, because in vitro astaxanthin enhanced thioredoxin reductase and had no effect on paraoxonase activity. Astaxanthin could be helpful in cardiovascular diseases by restoring thioredoxin reductase and paraoxonase activities.

Rapid regression of atherosclerosis: insights from the clinical and experimental literature

Looking back at animal and clinical studies published since the 1920s, the notion of rapid regression and stabilization of atherosclerosis in humans has evolved from a fanciful goal to one that might be achievable pharmacologically, even for advanced plaques. Our review of this literature indicates that successful regression of atherosclerosis generally requires robust measures to improve plasma lipoprotein profiles. Examples of such measures include extensive lowering of plasma concentrations of atherogenic apolipoprotein B (apoB)-lipoproteins and enhancement of 'reverse' lipid transport from atheromata into the liver, either alone or in combination. Possible mechanisms responsible for lesion shrinkage include decreased retention of apoB-lipoproteins within the arterial wall, efflux of cholesterol and other toxic lipids from plaques, emigration of foam cells out of the arterial wall, and influx of healthy phagocytes that remove necrotic debris and other components of the plaque. Unfortunately, the clinical agents currently available cause less dramatic changes in plasma lipoprotein levels, and, thereby, fail to stop most cardiovascular events. Hence, there is a clear need for testing of new agents expected to facilitate atherosclerosis regression. Additional mechanistic insights will allow further progress.

Cellular and molecular mechanisms for rapid regression of atherosclerosis: from bench top to potentially achievable clinical goal

PURPOSE OF REVIEW

Decades of literature have unambiguously demonstrated regression and remodeling of atherosclerotic lesions, including advanced plaques. Recent insights into underlying mechanisms are reviewed.

RECENT FINDINGS

Factors promoting regression include decreased apolipoprotein B-lipoprotein retention within the arterial wall, efflux of cholesterol and other harmful lipids from plaques, and emigration of lesional foam cells followed by entry of healthy phagocytes that remove necrotic debris and other plaque components. Cellular lipid efflux and foam cell emigration can occur surprisingly rapidly once the plaque milieu is improved. Lipid efflux and foam cell emigration each involve specific molecular mediators, many of which have been identified. Necrotic debris removal can be surprisingly comprehensive, with essentially full disappearance documented in animal models.

SUMMARY

The essential prerequisite for regression is robust improvement in plaque milieu, meaning large plasma reductions in atherogenic apolipoprotein B-lipoproteins or brisk enhancements in 'reverse' lipid transport from plaque into liver. Importantly, the processes of regression are consistent with rapid correction of features characteristic of the rupture-prone, vulnerable plaques responsible for acute coronary syndromes. New interventions to lower apolipoprotein B-lipoprotein levels and enhance reverse lipid transport may allow regression to become a widespread clinical goal. Strategies based on recent mechanistic insights may facilitate further therapeutic progress.

The lipoprotein lipase gene in combined hyperlipidemia: evidence of a protective allele depletion

Background

Lipoprotein Lipase (LPL), a key enzyme in lipid metabolism, catalyzes the hydrolysis of triglycerides (TG) from TG-rich lipoproteins, and serves a bridging function that enhances the cellular uptake of lipoproteins. Abnormalities in LPL function are associated with pathophysiological conditions, including familial combined hyperlipidemia (FCH). Whereas two LPL susceptibility alleles were found to co-segregate in a few FCH kindred, a role for common, protective alleles remains unexplored. The LPL Ser447Stop (S447X) allele is associated with anti-atherogenic lipid profiles and a modest reduction in risk for coronary disease. We hypothesize that significant depletion of the 447X allele exists in combined hyperlipidemia cases versus controls. A case-control design was employed. The polymorphism was assessed by restriction assay in 212 cases and 161 controls. Genotypic, allelic, and phenotypic associations were examined.

Results

We found evidence of significant allelic (447X_control: 0.130 vs. 447X_case: 0.031, χ² = 29.085; 1df; p < 0.001) and genotypic association (SS: 0.745 vs. 0.939, and SX+XX: 0.255 vs. 0.061) in controls and cases, respectively (χ² = 26.09; 1df; p < 0.001). In cases, depletion of the 447X allele is associated with a significant elevation in very-low-density lipoprotein cholesterol (VLDL-C, p = 0.045). Consonant with previous studies of this polymorphism, regression models predict that carriers of the 447X allele displayed significantly lower TG, low-density lipoprotein cholesterol (LDL-C) and TG/high-density lipoprotein cholesterol (HDL-C) ratio.

Conclusion

These findings suggest a role for the S447X polymorphism in combined hyperlipidemia and demonstrate the importance of evaluating both susceptibility and protective genetic risk factors.

Effect of preexisting statin use on expression of C-reactive protein, adhesion molecules, interleukin-6, and antioxidized low-density lipoprotein antibody in patients with unstable angina undergoing coronary stenting

BACKGROUND

Statins are believed to reduce coronary heart disease by mechanisms in addition to their well-known cholesterol lowering effect.

HYPOTHESIS

We studied the effect of statins on expression of C-reactive protein (CRP), interleukin-6 (IL-6), adhesion molecules, and antioxidized low-density lipoprotein antibody (anti-oxLDL Ab) in patients with unstable angina (Braunwald class IIb or IIIb) undergoing coronary stenting.

METHODS

Consecutive 50 patients with unstable angina were included in the study. We classified the study subjects as patients using statins (Group A, n=20, men 10, mean age 62 years) and patients not using statins (Group B, n=30, men 15, mean age 60 years).

RESULTS

Baseline levels of inflammatory markers were similar in the two groups. However, 24 h after coronary stenting, serum levels of CRP (2.00 vs. 4.63 mg/l, p < 0.05), intercellular adhesion molecule-1 (ICAM-1) (217 vs. 261 ng/ml, p < 0.01), and anti-oxLDL Ab (8.97 vs. 12.96 U/ml, p < 0.05) were significantly higher in Group B than in Group A. Furthermore, 72 h after coronary stenting, serum levels of CRP (3.00 vs. 5.50 mg/l, p < 0.01) and ICAM-1 (222 vs. 277 ng/ml, p < 0.05) were significantly higher in Group B than in Group A.

CONCLUSIONS

Preexisting statin therapy plays a role in reducing the serum levels of CRP, ICAM-1, and anti-oxLDL Ab after coronary stenting in patients with unstable angina. These data support an anti-inflammatory or plaque-stabilizing effect of statin therapy.

Gender and Ethnic Differences in a Case-Control Study of Dyslipidemia: Using the Apolipoprotein A-V Gene as an Exemplar in Cardiovascular Genetics

Common, complex genetic disorders such as coronary heart disease (CHD) frequently show large population differences, contributing to health disparities. It is also well known that CHD risk factor profiles and the frequency of coronary events differ by gender. Study of premature CHD has revealed that apolipoproteins are important discriminating factors for distinguishing individuals with CHD. Recent findings indicated that apolipoprotein A-V (APOA-V) gene promoter polymorphisms are an important determinant of plasma triglycerides (TG) and lipoprotein cholesterol, and a risk factor for CHD. Variations in APOA-V may have varying impacts in different ethnic groups. The purpose of this interdisciplinary genetic research project was to determine (1) the association of the APOA-V polymorphisms with lipoprotein profiles, and (2) the gender and ethnic differences in the T-1131C promoter polymorphism of the APOA-V gene in individuals with dyslipidemia versus controls. Results indicate that the minor -1131C allele (CC homozygotes + CT heterozygotes) was associated with elevated plasma TG (p= 0.007), very low density lipoprotein (VLDL)–TG (p= 0.019), LDL-TG (p= 0.004), high-density-lipoprotein (HDL)-TG (p< 0.001), and VLDL-cholesterol (p= 0.008). We found a striking elevation in the frequency of the minor C allele in Asians (p< 0.001) compared to Europeans. We also found a significant difference in genotype frequency between men and women in Asians (p= 0.031) and Europeans (p< 0.01). Remarkably, Asian women with the C allele have a 36% increase in TG compared to Asian women homozygous for the T allele. In summary, we found significant ethnic-specific and gender-based differences in the frequency of the minor allele of the -1131 APOA-V gene promoter polymorphism. Identification of genetic variations among ethnic groups and between genders may have significant potential for a better understanding of the development of cardiovascular disease.

Change in lipid profile and impairment of endothelium-dependent relaxation of blood vessels in rats after bile duct ligation

Hyperlipidemia, a condition normally observed in cholestatic liver disease, is also a risk factor for the development of atherosclerosis. The relationship between the elevation of lipoproteins in cholestatic liver diseases and atherosclerosis formation has not been elucidated. In this study, we propose that the impairment of endothelium-dependent relaxation (EDR) of blood vessels in cholestatic liver diseases may lead to the development of atherosclerosis. Using bile duct ligation (BDL) in rats as a model, we examined the liver function, serum lipid profile, EDR and morphologic change of the aorta from both sham operated and BDL rats. Significant increases in liver and spleen weights, serum alanine transaminase (ALT) and aspartate transaminase (AST) activities and the bilirubin level were observed in BDL rats. Upon bile duct ligation, the total and low-density lipoprotein cholesterol levels were increased but the high-density lipoprotein cholesterol and triglyceride levels were reduced. Less contractility and lowered response to acetylcholine-induced relaxation were found in aorta segments. In addition, the acetylcholine-induced relaxation was blocked by both L-NAME and 15 mM KCl. Our results suggest that both nitric oxide and endothelium-derived hyperpolarizing factor are important elements for the impairment of the EDR in BDL rats. In addition, a mild atrophy of the media of the aorta was detected in BDL rats. We conclude that the alterations of lipid profile and the mild atrophy of the media may lead to the impairment of EDR in the aorta in BDL rats, and these factors may potentiate the development of atherosclerosis.

Genetic analysis of a polymorphism in the human apoA-V gene: effect on plasma lipids

Recent discovery and characterization of APOAV suggests a role in metabolism of triglyceride (TG)-rich lipoproteins. Previously, variation at the APOAV locus was shown to modestly influence plasma TGs in normolipidemic samples. The aims of this study were to assess the effects of a polymorphism in APOAV (T-1131C) in terms of its frequency among three dyslipidemic populations and a control population, differences of allele frequency across available ethnic groups, and associations with specific lipoprotein TG and cholesterol compartments. We found a striking elevation in the frequency of the rare allele in a Chinese population (P = 0.0002) compared with Hispanic and European populations. The rare allele of the polymorphism was associated with elevated plasma TG (P = 0.012), VLDL cholesterol (P = 0.0007), and VLDL TG (P = 0.012), LDL TG (P = 0.003), and HDL TG (P = 0.016). Linear regression models predict that possession of the rare allele elevates plasma TG by 21 mg/dl (P = 0.009) and VLDL cholesterol by 8 mg/dl (P = 0.0001), and reduces HDL cholesterol by 2 mg/dl (P = 0.017). The association of the polymorphism with altered lipoprotein profiles was observed in combined hyperlipidemia, hypoalphalipoproteinemia, and hyperalphalipoproteinemia, and in controls. These findings indicate that APOAV is an important determinant of plasma TG and lipoprotein cholesterol, and is potentially a risk factor for cardiovascular disease.