Cholesterol mass efflux capacity and risk of peripheral artery disease: The Multi-Ethnic Study of Atherosclerosis

Racial and ethnic influences on carotid atherosclerosis: Epidemiology and risk factors

Carotid atherosclerosis-related stenosis, marked by atherosclerotic plaque formation in the carotid artery, significantly increases ischemic stroke risk. Its prevalence varies across ethnic groups, reflecting racial disparities. Epidemiological studies have highlighted different susceptibilities to carotid stenosis among racial groups. Native Americans and Whites show greater vulnerability, indicating genetic and environmental influences. The impact of carotid stenosis is more severe in Hispanic and Black populations, with a higher incidence of related brain injuries, underscoring the need for targeted interventions. Comparative imaging studies between Chinese and White individuals reveal unique patterns of carotid stenosis, enhancing understanding of its pathophysiology and management across ethnicities. This review also categorizes risk factors, distinguishing those with racial disparity (such as genetic loci, sleep apnea, and emotional factors, socioeconomic status) from those without. In summary, racial disparities affect carotid stenosis, leading to varying susceptibilities and outcomes among ethnic groups. Recognizing these differences is essential for developing effective prevention, diagnosis, and management strategies. Addressing these disparities is critical to reducing ischemic stroke's burden across populations. Continued research and targeted interventions are crucial to improve outcomes for individuals at risk of carotid stenosis and its complications.

Qihuang Zhuyu Formula Attenuates Atherosclerosis via Targeting PPARγ to Regulate Cholesterol Efflux and Endothelial Cell Inflammation

At present, due to the limitations of drug therapy targets for atherosclerosis, some patients fail to achieve satisfactory efficacy. Cholesterol efflux dysfunction and endothelial cell inflammation are considered to be important factors in the development of atherosclerosis. Peroxisome proliferator-activated receptor gamma (PPARγ), a promising therapeutic target for atherosclerosis, plays a dual role in regulating cholesterol efflux and endothelial cell inflammation. However, the use of PPARγ agonist in clinical practice is greatly limited as it could lead to water and sodium retention and hence result in congestive heart failure. Qihuang Zhuyu Formula (QHZYF) is a hospital preparation of Jiangsu Province Hospital of Chinese Medicine which has definite effect in the treatment of atherosclerosis, but its pharmacological mechanism has not been clear. In this study, we successfully predicted that QHZYF might regulate cholesterol efflux and endothelial inflammation via targeting PPARγ-mediated PPARγ/LXRα/ABCA1-ABCG1 and PPARγ/NF-κB p65 pathways by using UPLC-Q-TOF/MS, network pharmacology, bioinformatics analysis, and molecular docking technology. Subsequently, we confirmed in vivo that QHZYF could attenuate atherosclerosis in ApoE-/- mice and regulate the expression levels of related molecules in PPARγ/LXRα/ABCA1-ABCG1 and PPARγ/NF-κB p65 pathways of ApoE-/- mice and C57BL/6 wild-type mice. Finally, in in vitro experiments, we found that QHZYF could reduce lipid content and increase cholesterol efflux rate of RAW 264.7 cells, inhibit the inflammatory response of HUVECs, and regulate the expression levels of related molecules in the two pathways. In addition, the above effects of QHZYF were significantly weakened after PPARγ knockdown in the two kinds of cells. In conclusion, our study revealed that QHZYF attenuates atherosclerosis via targeting PPARγ-mediated PPARγ/LXRα/ABCA1-ABCG1 and PPARγ/NF-κB p65 pathways to regulate cholesterol efflux and endothelial cell inflammation. More importantly, our study offers a promising complementary and alternative therapy which is expected to make up for the limitation of current drug treatment methods and provide a valuable reference for new drugs development in the future.

Addressing dyslipidemic risk beyond LDL-cholesterol

Despite the success of LDL-lowering drugs in reducing cardiovascular disease (CVD), there remains a large burden of residual disease due in part to persistent dyslipidemia characterized by elevated levels of triglyceride-rich lipoproteins (TRLs) and reduced levels of HDL. This form of dyslipidemia is increasing globally as a result of the rising prevalence of obesity and metabolic syndrome. Accumulating evidence suggests that impaired hepatic clearance of cholesterol-rich TRL remnants leads to their accumulation in arteries, promoting foam cell formation and inflammation. Low levels of HDL may associate with reduced cholesterol efflux from foam cells, aggravating atherosclerosis. While fibrates and fish oils reduce TRL, they have not been uniformly successful in reducing CVD, and there is a large unmet need for new approaches to reduce remnants and CVD. Rare genetic variants that lower triglyceride levels via activation of lipolysis and associate with reduced CVD suggest new approaches to treating dyslipidemia. Apolipoprotein C3 (APOC3) and angiopoietin-like 3 (ANGPTL3) have emerged as targets for inhibition by antibody, antisense, or RNAi approaches. Inhibition of either molecule lowers TRL but respectively raises or lowers HDL levels. Large clinical trials of such agents in patients with high CVD risk and elevated levels of TRL will be required to demonstrate efficacy of these approaches.

Artesunate attenuates foam cell formation by enhancing cholesterol efflux

Background

Atherosclerosis is the main cause of many cardiovascular diseases and the second leading cause of death in elderly people. The formation of intimal macrophage-derived foam cells is a major feature of early atherosclerotic lesions. Little is known about the effects of artesunate (ART) on macrophage-derived foam cell formation.

Methods

Oil red O staining was employed to detect foam cell formation; colorimetric analysis was employed for cholesterol measurement; quantitative real time polymerase chain reaction (qRT-PCR) and western blot analysis were employed to assess messenger RNA (mRNA) and protein expression, respectively; enzyme-linked immunosorbent assay (ELISA) analyses were used to observe interleukin 6 (IL-6) and tumor necrosis factor-α (TNF-α) release; and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays were used to examine cell viability.

Results

It was revealed that ART attenuated oxidized low-density lipoprotein (ox-LDL)-induced foam cell formation from THP-1-derived macrophages by decreasing cholesterol accumulation, and the effect might have occurred via enhanced cholesterol efflux. Additionally, ART decreased toll-like receptor 4 (TLR4) expression, increased adenosine triphosphate (ATP)-binding cassette transporter A1 (ABCA1) and ATP-binding cassette transporter G1 (ABCG1) expression, and reduced the secretion of IL-6 and TNF-α.

Conclusions

This study showed that ART attenuated the ox-LDL-induced formation of foam cells from THP-1-derived macrophages by increasing ABCA1 and ABCG1 expression via inhibiting TLR4 expression and reducing TNF-α and IL-6 secretion from macrophages induced by ox-LDL, which ultimately decreased the accumulation of cholesterol. It is worthwhile further investigate ART as a potential drug for the treatment of atherosclerosis.

Cholesterol Efflux Capacity Associates with the Ankle-Brachial Index but Not All-Cause Mortality in Patients with Peripheral Artery Disease

BACKGROUND

Cholesterol efflux is an important mechanism by which high-density lipoproteins (HDLs) protect against cardiovascular disease. As peripheral artery disease (PAD) is associated with high mortality rates, mainly due to cardiovascular causes, we investigated whether cholesterol efflux capacity (CEC) of apolipoprotein B (apoB)-depleted plasma, a widely used surrogate of HDL function, may serve as a predictive marker for mortality in this patient population.

METHODS

In this prospective single-center study (median follow-up time: 9.3 years), apoB-containing lipoproteins were precipitated from plasma of 95 patients with PAD and incubated with J744-macrophages, which were loaded with radiolabeled cholesterol. CEC was defined as the fractional radiolabel released during 4 h of incubation.

RESULTS

Baseline CEC was lower in PAD patients that currently smoked (p = 0.015) and had a history of myocardial infarction (p = 0.011). Moreover, CEC showed a significant correlation with HDL-cholesterol (p = 0.003) and apolipoprotein A-I levels (p = 0.001) as well as the ankle-brachial index (ABI, p = 0.018). However, CEC did not differ between survivors and non-survivors. Neither revealed Kaplan-Meier and Cox regression analyses any significant association of CEC with all-cause mortality rates.

CONCLUSION

Taken together, CEC is associated with ABI but does not predict all-cause mortality in patients with PAD.

Cholesterol efflux pathways, inflammation, and atherosclerosis

Plasma levels of high-density lipoprotein (HDL) inversely correlate with the incidence of cardiovascular diseases (CVD). The causal relationship between plasma HDL-cholesterol levels and CVD has been called into question by Mendelian randomization studies and the majority of clinical trials not showing any benefit of plasma HDL-cholesterol raising drugs on CVD. Nonetheless, recent Mendelian randomization studies including an increased number of CVD cases compared to earlier studies have confirmed that HDL-cholesterol levels and CVD are causally linked. Moreover, several studies in large population cohorts have shown that the cholesterol efflux capacity of HDL inversely correlates with CVD. Cholesterol efflux pathways exert anti-inflammatory and anti-atherogenic effects by suppressing proliferation of hematopoietic stem and progenitor cells, and inflammation and inflammasome activation in macrophages. Cholesterol efflux pathways also suppress the accumulation of cholesteryl esters in macrophages, i.e. macrophage foam cell formation. Recent single-cell RNASeq studies on atherosclerotic plaques have suggested that macrophage foam cells have lower expression of inflammatory genes than non-foam cells, probably reflecting liver X receptor activation, upregulation of ATP Binding Cassette A1 and G1 cholesterol transporters and suppression of inflammation. However, when these pathways are defective lesional foam cells may become pro-inflammatory.

Association between cholesterol efflux capacity and peripheral artery disease in coronary heart disease patients with and without type 2 diabetes: from the CORDIOPREV study

Background

Peripheral artery disease (PAD) is recognized as a significant predictor of mortality and adverse cardiovascular outcomes in patients with coronary heart disease (CHD). In fact, coexisting PAD and CHD is strongly associated with a greater coronary event recurrence compared with either one of them alone. High-density lipoprotein (HDL)-mediated cholesterol efflux capacity (CEC) is found to be inversely associated with an increased risk of incident CHD. However, this association is not established in patients with PAD in the context of secondary prevention. In this sense, our main aim was to evaluate the association between CEC and PAD in patients with CHD and whether the concurrent presence of PAD and T2DM influences this association.

Methods

CHD patients (n = 1002) from the CORDIOPREV study were classified according to the presence or absence of PAD (ankle-brachial index, ABI ≤ 0.9 and ABI > 0.9 and < 1.4, respectively) and T2DM status. CEC was quantified by incubation of cholesterol-loaded THP-1 cells with the participants' apoB-depleted plasma was performed.

Results

The presence of PAD determined low CEC in non-T2DM and newly-diagnosed T2DM patients. Coexisting PAD and newly-diagnosed T2DM provided and additive effect providing an impaired CEC compared to non-T2DM patients with PAD. In established T2DM patients, the presence of PAD did not determine differences in CEC, compared to those without PAD, which may be restored by glucose-lowering treatment.

Conclusions

Our findings suggest an inverse relationship between CEC and PAD in CHD patients. These results support the importance of identifying underlying mechanisms of PAD, in the context of secondary prevention, that provide potential therapeutic targets, that is the case of CEC, and establishing strategies to prevent or reduce the high risk of cardiovascular events of these patients.

Trial registrationhttps://clinicaltrials.gov/ct2/show/NCT00924937. Unique Identifier: NCT00924937

High Density Lipoprotein Cholesterol Efflux Capacity and Atherosclerosis in Cardiovascular Disease: Pathophysiological Aspects and Pharmacological Perspectives

Over the years, the relationship between high-density lipoprotein (HDL) and atherosclerosis, initially highlighted by the Framingham study, has been revealed to be extremely complex, due to the multiple HDL functions involved in atheroprotection. Among them, HDL cholesterol efflux capacity (CEC), the ability of HDL to promote cell cholesterol efflux from cells, has emerged as a better predictor of cardiovascular (CV) risk compared to merely plasma HDL-cholesterol (HDL-C) levels. HDL CEC is impaired in many genetic and pathological conditions associated to high CV risk such as dyslipidemia, chronic kidney disease, diabetes, inflammatory and autoimmune diseases, endocrine disorders, etc. The present review describes the current knowledge on HDL CEC modifications in these conditions, focusing on the most recent human studies and on genetic and pathophysiologic aspects. In addition, the most relevant strategies possibly modulating HDL CEC, including lifestyle modifications, as well as nutraceutical and pharmacological interventions, will be discussed. The objective of this review is to help understanding whether, from the current evidence, HDL CEC may be considered as a valid biomarker of CV risk and a potential pharmacological target for novel therapeutic approaches.