Relationship of Para and Perirenal Fat and High-Density Lipoprotein and Its Function in Patients with Type 2 Diabetes Mellitus

Background. Para and perirenal fat is a fat pad surrounding the kidneys. Recent studies showed the association between para and perirenal fat and cardiovascular diseases including atherosclerosis and hypertension. We aimed to assess the relationship between para-perirenal ultrasonographic fat thickness and serum high-density lipoprotein (HDL) level and cholesterol efflux capacity of HDL in patients with type 2 diabetes mellitus (T2DM). Methods. We recruited 58 subjects with T2DM and collected anthropometric indices including height, weight, waist circumference, and other clinical data. Para-perirenal ultrasonographic fat thickness (PUFT) was measured via ultrasound. Serum lipid profile and other metabolic indices were determined as well. Correlation analysis and regression analysis were performed to analyze the relationship between PUFT and HDL level and cholesterol efflux capacity in all patients and subgroups. Results. Patients with higher PUFT have lower serum HDL level but increased cholesterol efflux capacity. Further analysis showed that PUFT negatively correlated with the serum HDL level in all patients, with no difference in groups divided by body mass index (BMI). In addition, PUFT was positively correlated with cholesterol efflux capacity in all patients. Multiple stepwise regression analysis showed an independent association of PUFT and serum HDL level and cholesterol efflux capacity. Conclusions. PUFT is closely correlated with the serum HDL level and cholesterol efflux capacity in patients with T2DM.

Cholesterol Efflux Capacity and Its Association With Adverse Cardiovascular Events: A Systematic Review and Meta-Analysis

Background: Serum high-density lipoprotein cholesterol (HDL-C) levels are inversely associated with cardiovascular disease events. Yet, emerging evidence suggests that it is the functional properties of HDL, in particular, reverse cholesterol transport, which is a key protective mechanism mediating cholesterol removal from macrophage cells and reducing plaque lipid content. Cholesterol efflux capacity (CEC) measures the capacity of HDL to perform this function. A systematic review and meta-analysis were conducted to explore the association of CEC and adverse cardiovascular events.Methods: A comprehensive literature review of Embase, PubMed, and Web of Science Core Collection from inception to September 2019 was performed for all studies that examined the association between CEC and cardiovascular outcomes. The primary outcome was adverse cardiovascular events, which were inclusive of atherosclerotic cardiovascular disease (ASCVD) or mortality.Results: A total of 20 trials were included. Compared with low CEC levels, high CEC levels were associated with a 37% lower risk of adverse cardiovascular events (crude RR = 0.63; 95% CI, 0.52–0.76; P < 0.00001). Every SD increase of CEC was associated with a 20% lower risk of adverse cardiovascular events (HR = 0.80; 95% CI, 0.66–0.97; P = 0.02). The association remained significant after adjusting for cardiovascular risk factors, medications, and HDL-C levels (HR = 0.76; 95% CI, 0.63–0.91; P = 0.004). A significant CEC-endpoint relationship was observed (P = 0.024) such that for every 0.1 unit increase in CEC, there was a 5% reduced risk for adverse cardiovascular events (RR = 0.95; 95% CI, 0.91–0.99).Conclusions: Higher CEC is associated with lower adverse cardiovascular outcomes. These findings warrant further research on whether CEC is merely a biomarker or a mechanism that could be targeted as a pharmacologic intervention for improving clinical outcomes.PROSPERO Registration Number: CRD42020146681; https://www.crd.york.ac.uk/prospero/.

Phospholipase A2 group IIA correlates with circulating high-density lipoprotein cholesterol and modulates cholesterol efflux possibly through regulation of PPAR-γ/LXR-α/ABCA1 in macrophages

Background Secretory phospholipase A2 group IIA (sPLA2-IIA) is an independent risk factor for cardiovascular disease, but its role on high-density lipoprotein cholesterol (HDL-C) level has not been clarified. The aim of the present study was to explore the association between circulating sPLA2-IIA and HDL-C, and to evaluate if sPLA2-IIA enhances cholesterol efflux capacity through regulation of peroxisome proliferator-activated receptor γ (PPAR-γ), liver X receptor α (LXR-α), and ATP-binding cassette A1 (ABCA1). Methods 131 patients with coronary artery disease were enrolled. The plasma level of sPLA2-IIA was tested with enzyme-linked immunosorbent assay kit, and serum lipids were assessed by biochemical analyzer. Human monocyte-macrophage cell line THP-1 was co-incubated with sPLA2-IIA in the presence/absence of selective PPAR-γ antagonist GW9662 in vitro. Real-time PCR and Western-blot were employed to measure the mRNA and protein expressions of PPAR-γ, LXR-α, and ABCA1, respectively. The cholesterol efflux was evaluated by using an assay kit. Results In subjects, circulating level of sPLA2-IIA was positively related with that of HDL-C (r = 0.196, p = 0.024). The plasma level of sPLA2-IIA was significantly higher in the high HDL-C (≥ 1.04 mmol/L) group (7477.828 pg/mL) than that in low HDL-C (< 1.04 mmol/L) group (5836.92 pg/mL, p = 0.004). For each increase of 1 pg/μl in sPLA2-IIA level, the adjusted odds ratio for HDL-C ≥ 1.04 mmol/L was 1.143. Co-incubation of THP-1 cells with sPLA2-IIA resulted in increased expressions of PPAR-γ, LXR-α, and ABCA1, as well as enhanced cholesterol efflux capacity, that were all reversed by administration of GW9662. Conclusions Circulating sPLA2-IIA was positively associated with HDL-C. PPAR-γ/LXR-α/ABCA1 might be responsible for sPLA2-IIA-regulated cholesterol efflux in macrophages.

EXPRESS: Novel cholesterol efflux assay using immobilized liposome-bound gel beads: Confirmation and improvement for application in clinical laboratory

Objectives Cholesterol efflux capacity (CEC), an atheroprotective function of high-density lipoprotein, is expected to be a potential biomarker for cardiovascular disease. However, CEC has not been widely introduced for application in clinical laboratories because of the complexity of the conventional CEC assay using cells and radioactive materials. Previously, we developed a novel CEC assay using immobilized liposome-bound gel beads (ILG), which solves these issues. We aimed to confirm the validation and further improve the ILG method for application in the clinical setting. Methods Cholesterol efflux capacity values by the ILG method assayed for shorter incubation time (4 h) were compared to those assayed for 16 h (our previous ILG method). To investigate a reference material that can correct the variation between ILG manufacturing lots, bovine serum albumin, human gamma-globulins, and globulin complexes were evaluated. CEC values were also estimated in plasmas obtained with different anticoagulants, serum treated with freeze-thaw cycles, and serum mixed with several interference substances. Results The CEC of 4- and 16-h incubation times were well correlated. Globulin complexes may be used as a reference material. Plasma can be used as the specimen. The serum and stored temperature of the specimen did not largely affect CEC. Hemoglobin and chyle did not have an effect on CEC, whereas high-bilirubin serum showed elevated CEC. The effect of bilirubin was nearly canceled by subtracting basal fluorescence intensity. Conclusions Present ILG method further fulfills some requirements for application in clinical laboratory. Using this reliable simple method, evaluation for clinical significance of CEC is expected.

Serum cholesterol efflux capacity is associated with coronary plaque progression in patients with coronary heart disease

Background Coronary plaque progression is a major risk factor of adverse cardiac events in patients with coronary heart disease (CHD). Emerging evidence showed that attenuated high-density lipoprotein (HDL) function measured by cholesterol efflux capacity (CEC) was associated with development of atherosclerosis independent of HDL cholesterol level. In this study, we sought to investigate whether CEC is a predictor for coronary plaque progression in CHD patients. Methods We consecutively enrolled CHD patients from January 2017 to August 2019 in our Hospital who underwent elective percutaneous coronary intervention and had at least one non-target coronary lesion. Follow-up coronary angiography were performed at around 12 months. Fluorescence-labeled cholesterol and J774 macrophages were used to measure the CEC of ApoB-depleted serum sample from all patients. Quantitative coronary angiography (QCA) was performed both at baseline and follow-up to analyze the plaque progression. Results A total of 430 CHD patients with 586 non-target coronary lesions were included in the final analysis. During a mean follow-up time of 381.04±59.52 days, patients with decreased CEC presented more severe plaque progression (net luminal loss in highest to lowest CEC quartile: 0.22±0.42mm vs 0.20±0.41mm vs 0.13±0.36mm vs 0.11±0.34mm, p=0.035). In multivariate analysis, baseline CEC was independently associated with coronary plaque progression after adjustment for traditional risk factors including HDL cholesterol and ApoA-I, no matter treated as categorical variable (OR: 0.382 [95% CI 0.180–0.781] for highest to lowest quartile) or continuous variable (OR: 0.522 [95% CI 0.373–0.714] for per SD increase]. Furthermore, CEC demonstrated a better power in predicting coronary plaque progression compared with HDL cholesterol concentration (AUC=0.644 vs 0.514). Conclusions This study suggests that HDL function reflected by serum CEC is an independent predictor for coronary plaque progression in CHD patients. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Natural Science Foundation of China, Shanghai Municipal Commission of Health and Family Planning

Molecular Patterns of Extreme and Persistent Cholesterol Efflux Capacity

Objective: Cholesterol efflux capacity (CEC), the ability of extracellular acceptors to pick-up cholesterol from macrophages, is a clinically relevant cardiovascular biomarker. CEC is inversely associated with incident atherosclerotic cardiovascular disease events. However, CEC is only modestly associated with HDL-C (high-density lipoprotein cholesterol) levels, which may explain the failure of HDL-C raising therapies to improve atherosclerotic cardiovascular disease outcomes. Determinants of variation in CEC are not well understood. Thus, we sought to establish whether extreme high and low CEC is a robust persistent phenotype and to characterize associations with cholesterol, protein, and phospholipids across the particle size distribution. Approach and Results: CEC was previously measured in 2924 participants enrolled in the Dallas Heart Study, a multi-ethnic population-based study from 2000 to 2002. We prospectively recruited those who were below the 10th and above 90th percentile of CEC. Our study revealed that extreme low and high CEC are persistent, robust phenotypes after 15 years of follow-up. Using size exclusion chromatography, CEC to fractionated plasma depleted of apolipoprotein B (fraction-specific CEC) demonstrated significant differences in CEC patterns between persistent high and low efflux groups. Fraction-specific CEC was correlated with fraction-specific total phospholipid but not apolipoprotein A-I, cholesterol, or total protein. These correlations varied across the size distribution and differed among persistent high versus low efflux groups. Conclusions: Extreme high and low CEC are persistent and robust phenotypes. CEC patterns in fractionated plasma reveal marked variation across the size distribution. Future studies are warranted to determine specific molecular species linked to CEC in a size-specific manner.

Cholesterol efflux capacity and its association with prevalent metabolic syndrome in a multi-ethnic population (Dallas Heart Study)

Metabolic syndrome (MetS) is characterized by adiposity and atherogenic dyslipidemia consisting of elevated triglyceride and decreased high density lipoprotein cholesterol (HDL-C) levels however, cholesterol concentration alone does not reflect HDL functionality. Cholesterol efflux capacity (CEC) captures a key anti-atherosclerotic function of HDL; studies linking CEC to MetS have yielded inconsistent findings and lacked racial/ethnic diversity. The aim of this study was to evaluate the association between CEC and MetS in a large multi-ethnic population utilizing two different CEC assays interrogating overlapping but distinct reverse cholesterol transport pathways. A cross-sectional study was performed using the Dallas Heart Study cohort and cholesterol efflux was measured with radiolabeled and fluorescent cholesterol assays. The relationship between CEC and MetS was assessed using multivariable regression analyses. A total of 2241 participants were included (mean age was 50 years; 38% men and 53% Blacks). CEC was independently and inversely associated with MetS irrespective of efflux assay (CEC-radiolabeled, adjusted OR 0·71 [95% CI 0·65–0·80]. CEC-fluorescent, adjusted OR 0·85 [95% CI 0·77–0·94]). Both CEC measures were inversely associated with waist circumference and directly associated with HDL-C but not with other MetS components. There was an interaction by sex but not by race such that the inverse associations between CEC and MetS were somewhat attenuated in men (OR 0·86, 95%CI 0·74–1·01). In this large multi-ethnic cohort, impaired CEC is linked to MetS irrespective of efflux assay and race/ethnicity but less so among men. Future studies are needed to assess whether CEC mediates the atherosclerotic cardiovascular disease risk of MetS.

Independent Effects of Kidney Function and Cholesterol Efflux on Cardiovascular Mortality

BackgroundImpaired renal function is associated with cardiovascular and all-cause mortality. In the general population, HDL-cholesterol is associated with cardiovascular events, which is not true in patients with chronic kidney disease (CKD). This has been attributed to abnormal HDL function in CKD.MethodsIn this study, we analyzed the association between kidney function, cholesterol efflux capacity as one of the major HDL functions and cardiovascular mortality in 2469 patients of the Ludwigshafen Risk and Cardiovascular Health Study who all underwent coronary angiography.ResultsWe found a strong association between cholesterol efflux capacity and kidney function. Additionally, a genetic score of 53 SNPs associated with GRF and the uromodulin SNP rs12917707 was correlated inversely with cholesterol efflux. However, adjustment for eGFR and uromodulin as markers of kidney function did not affect the relationship between cholesterol efflux and cardiovascular mortality.ConclusionsWe suggest that impaired renal function lowers cholesterol efflux, but that this is not mediating the effects of impaired kidney function on cardiovascular mortality. Other mechanisms of low cellular cholesterol efflux may causally be involved in adverse cardiovascular outcomes.Trial registrationThe study was approved by the Ethics Committee at the “Aerztekammer Rheinland-Pfalz” and was performed conform to the declaration of Helsinki (837.255.97 [1394], approved January 8th, 1999).