Expression levels of miR-27a, miR-329, ABCA1, and ABCG1 genes in peripheral blood mononuclear cells and their correlation with serum levels of oxidative stress and hs-CRP in the patients with coronary artery disease.

Atherosclerosis is a chronic inflammatory disease with high mortality worldwide. The reverse cholesterol transport pathway in macrophage plays an important role in the pathogenesis of coronary artery disease (CAD) and is strongly controlled by regulatory factors. The microRNAs can promote or prevent the formation of atherosclerotic lesions by post-transcriptional regulation of vital genes in this pathway. Therefore, this study was conducted to investigate the relationship between the expression levels of miR-27a, miR-329, ABCA1, and ABCG1 genes and serum levels of hs-CRP, ox-LDL, and indices of oxidative stress in the patients with established CAD and controls. A total of 84 subjects (42 patients with CAD and 42 controls) were included in this study. Expression levels of miR-27a-3p, miR-329-3p, ABCA1, and ABCG1 genes in the peripheral blood mononuclear cells (PBMCs) and serum concentration of hs-CRP and ox-LDL were measured by real time-PCR and ELISA, respectively. Also, oxidative stress parameters in the serum were evaluated by ferric-reducing antioxidant power (FRAP) and malondialdehyde (MDA) assays. ABCA1 and ABCG1 gene expression in PBMC and serum concentration of FRAP were significantly lower in the CAD group compared to the control group. Expression levels of miR-27a and miR-329 and serum levels of hs-CRP, ox-LDL, and MDA were significantly higher in the CAD group compared to the control group. Serum levels of hs-CRP, ox-LDL, and expression level of miR-27a have inversely related to ABCA1 and ABCG1 gene expression in all the subjects. An increase in the expression levels of miR-27a and miR-329 may lead to the progression of atherosclerosis plaque by downregulating the expression of ABCA1 and ABCG1 genes.

Effect of ABCA1 promoter methylation on premature coronary artery disease and its relationship with inflammation.

BACKGROUND: ATP-binding cassette transporter A1 (ABCA1) plays a major role in high-density lipoprotein (HDL) metabolism and reverse cholesterol transport (RCT) and exerts anti-inflammatory effects. Increased ABCA1 promoter methylation level may result in the progression of coronary artery disease. Thus, the present study investigated the association between promoter methylation status of ABCA1 and inflammation in the development of premature coronary artery disease (pCAD). METHODS: PCAD patients and healthy individuals (n = 90 each) were recruited from the Characteristic Medical Center of the Chinese People's Armed Police Force from June to December 2019. Using pyrosequencing, the levels of ABCA1 promoter methylation in their blood samples were evaluated. Serum concentrations of lipids, interleukin 1ß (IL-1ß), C-reactive protein (CRP), and circulating free DNA/Neutrophil extracellular traps (cfDNA/NETs) were also routinely measured and compared between the two groups. P values < 0.05 were considered statistically significant. RESULTS: The mean ABCA1 promoter methylation levels were significantly higher in the pCAD group than in the control group (44.24% ± 3.66 vs. 36.05% ± 2.99, P < 0.001). Based on binary logistic regression analysis, ABCA1 promoter methylation level was identified as an independent risk factor for pCAD development (odds ratio = 2.878, 95% confidence interval: 1.802-4.594, P < 0.001). Furthermore, ABCA1 promoter methylation levels were negatively correlated with HDL levels (r = - 0.488, P < 0.001) and positively correlated with the levels of CRP, cfDNA/NETs, and IL-1ß (r = 0.389, 0.404, 0.385, respectively; P < 0.001). Multiple regression analysis showed that the serum levels of CRP, IL-1ß, and cfDNA/NETs independently affect ABCA1 promoter methylation. CONCLUSIONS: Our findings indicate that high methylation levels at the ABCA1 promoter are associated with low HDL cholesterol levels and an increased risk of pCAD. Inflammatory factors and NETs may be involved in the progression of pCAD by affecting ABCA1 promoter methylation levels.

Progress in finding pathogenic DNA copy number variations in dyslipidemia.

PURPOSE OF REVIEW: DNA copy number variations (CNVs) are large-scale mutations that include deletions and duplications larger than 50 bp in size. In the era when single-nucleotide variations were the major focus of genetic technology and research, CNVs were largely overlooked. However, CNVs clearly underlie a substantial proportion of clinical disorders. Here, we update recent progress in identifying CNVs in dyslipidemias. RECENT FINDINGS: Until last year, only the LDLR and LPA genes were appreciated as loci within which clinically relevant CNVs contributed to familial hypercholesterolemia and variation in Lp(a) levels, respectively. Since 2017, next-generation sequencing panels have identified pathogenic CNVs in at least five more genes underlying dyslipidemias, including a PCSK9 whole-gene duplication in familial hypercholesterolemia; LPL, GPIHBP1, and APOC2 deletions in hypertriglyceridemia; and ABCA1 deletions in hypoalphalipoproteinemia. SUMMARY: CNVs are an important class of mutation that contribute to the molecular genetic heterogeneity underlying dyslipidemias. Clinical applications of next-generation sequencing technologies need to consider CNVs concurrently with familiar small-scale genetic variation, given the likely implications for improved diagnosis and treatment.

High-Density Lipoprotein Particles, Cell-Cholesterol Efflux, and Coronary Heart Disease Risk.

Objective- The cell-cholesterol efflux capacity of HDL (high-density lipoprotein) is inversely associated with coronary heart disease risk. ABCA1 (ATP-binding cassette transporter A1) plays a crucial role in cholesterol efflux from macrophages to preß-1-HDL. We tested the hypothesis that coronary heart disease patients have functionally abnormal preß-1-HDL. Approach and Results- HDL cell-cholesterol efflux capacity via the ABCA1 and the SR-BI (scavenger receptor class B type I) pathways, HDL antioxidative capacity, apo (apolipoprotein) A-I-containing HDL particles, and inflammatory- and oxidative-stress markers were measured in a case-control study of 100 coronary heart disease cases and 100 sex-matched controls. There were significant positive correlations between ABCA1-dependent cholesterol efflux and the levels of small lipid-poor preß-1 particles ( R2=0.535) and between SR-BI-dependent cholesterol efflux and the levels of large lipid-rich (α-1+α-2) HDL particles ( R2=0.712). Cases had significantly higher (87%) preß-1 concentrations than controls, but the functionality of their preß-1 particles (preß-1 concentration normalized ABCA1-dependent efflux capacity) was significantly lower (-31%). Cases had significantly lower (-12%) mean concentration of large HDL particles, but the functionality of their particles (α-1+α-2 concentration normalized SR-BI-dependent efflux capacity) was significantly higher (22%) compared with that of controls. HDL antioxidative capacity was significantly lower (-16%) in cases than in controls. There were no significant correlations between either preß-1 functionality or large HDL particle functionality with HDL antioxidative capacity or the concentrations of inflammatory- and oxidative-stress markers. Conclusions- HDL cell-cholesterol efflux capacity is significantly influenced by both the concentration and the functionality of specific HDL particles participating in cell-cholesterol efflux. Coronary heart disease patients have higher than normal preß-1 concentrations with decreased functionality and lower than normal large HDL particle concentrations with enhanced functionality.

Signature MicroRNA expression profile is associated with lipid metabolism in African green monkey.

BACKGROUND: Non-human primates (NHPs) are important models of medical research on obesity and cardiovascular diseases. As two of the most commonly used NHPs, cynomolgus macaque (CM) and African green monkey (AGM) own different capacities in lipid metabolism of which the mechanism is unknown. This study investigated the expression profiles of lipid metabolism-related microRNAs (miRNAs) in CM and AGM and their possible roles in controlling lipid metabolism-related gene expression. METHODS: By small RNA deep sequencing, the plasma miRNA expression patterns of CM and AGM were compared. The lipid metabolism-related miRNAs were validated through quantitative reverse-transcription (RT) polymerase chain reaction (PCR). Related-target genes were predicted by TargetScan and validated in Vero cells. RESULTS: Compared to CM, 85 miRNAs were upregulated with over 1.5-fold change in AGM of which 12 miRNAs were related to lipid metabolism. miR-122, miR-9, miR-185, miR-182 exhibited the greatest fold changes(fold changes are 51.2, 3.8, 3.7, 3.3 respectively; all P < 0.01). And 77 miRNAs were downregulated with over 1.5-fold change in AGM of which 3, miR-370, miR-26, miR-128 (fold changes are 9.3, 1.8, 1.7 respectively; all P < 0.05) were related to lipid metabolism. The lipid metabolism-related gene targets were predicted by TargetScan and confirmed in the Vero cells. CONCLUSION: We report for the first time a circulating lipid metabolism-related miRNA profile for CM and AGM, which may add to knowledge of differences between these two non-human primate species and miRNAs' roles in lipid metabolism.

Shexiang Baoxin Pill Alleviates the Atherosclerotic Lesions in Mice via Improving Inflammation Response and Inhibiting Lipid Accumulation in the Arterial Wall.

Epidemiological studies have demonstrated that cardiovascular diseases (CVDs) are the leading cause of death in the world. Atherosclerosis, a kind of chronic vascular disorder related to multiple pathogenic processes, has been reported to be an underlying cause of CVDs. Shexiang Baoxin Pill (SBP) is a traditional Chinese medicine formulation and has been broadly used for the treatment of CVDs in East Asia. However, whether SBP affects the development of atherosclerosis is poorly understood. The aim of this study was to investigate the antiatherosclerotic roles and relevant mechanisms of SBP in apolipoprotein E knockout mice. Our results showed that SBP treatment markedly decreased the size of atherosclerotic plaques of the entire aorta and the aortic sinus. Biochemical analyses indicated that SBP gavage improved oxidative stress in vivo, as seen by the level elevation of SOD, CAT, and GSH and the level reduction of MDA, H2O2, and MPO. Moreover, the concentration of MCP-1, IFN-γ, and IL-17A was reduced, and the content of IL-10 and TGF-ß1 was increased in the serum from SBP-treated mice. We discovered that the expression levels of inflammatory factors including VCAM-1, ICAM-1, IL-6, and IL-2 in the vascular wall of the SBP group were also decreased in comparison with those of the normal saline group. Moreover, we found that SBP alleviated the activation of inflammation-related pathways in the aorta tissue, as seen by the level elevation of Mfn2 and reduced phosphorylation of p38, JNK, and NF-κB. Furthermore, western blot showed that SBP administration reduced the level of SR-A and LOX-1 and elevated the content of LXRα, ABCA1, and ABCG1 in the arterial wall, indicating that SBP was capable of alleviating lipid influx and facilitating lipid efflux. In conclusion, our data suggested that SBP exerted antiatherosclerotic effects via improving inflammation response and inhibiting lipid accumulation.

Plasma PCSK9 levels and lipoprotein distribution are preserved in carriers of genetic HDL disorders.

Proprotein convertase subtilisin/kexin 9 (PCSK9), a protein regulating the number of cell-surface LDL receptors (LDLR), circulates partially associated to plasma lipoproteins. How this interaction alters PCSK9 plasma levels is still unclear. In the present study, we took advantage of the availability of a large cohort of carriers of genetic HDL disorders to evaluate how HDL defects affect plasma PCSK9 levels and its distribution among lipoproteins. Plasma PCSK9 concentrations were determined by ELISA in carriers of mutations in LCAT, ABCA1, or APOAI genes, and lipoprotein distribution was analyzed by FPLC. Carriers of one or two mutations in the LCAT gene show plasma PCSK9 levels comparable to that of unaffected family controls (homozygotes, 159.4 ng/mL (124.9;243.3); heterozygotes, 180.3 ng/mL (127.6;251.5) and controls, 190.4 ng/mL (146.7;264.4); P for trend = 0.33). Measurement of PCSK9 in plasma of subjects carrying mutations in ABCA1 or APOAI genes confirmed normal values. When fractionated by FPLC, PCSK9 peaked in a region between LDL and HDL in control subjects. In carriers of all HDL defects, lipoprotein profile shows a strong reduction of HDL, but the distribution of PCSK9 was superimposable to that of controls. In conclusion, the present study demonstrates that in genetically determined low HDL states plasma PCSK9 concentrations and lipoprotein distribution are preserved, thus suggesting that HDL may not be involved in PCSK9 transport in plasma.

Aberrant expression of plasma microRNA-33a in an atherosclerosis-risk group.

In order to investigate whether plasma microRNA-33a (miR-33a) can be a biomarker for the early detection of atherosclerosis and to reexamine the assumption that miR-33a represses the expression of ABCA1, we compared the expression levels of miR-33a and ATP-binding cassette A1 (ABCA1) using human plasma and supernatants of macrophage cultured media. We first separated ample number of plasma samples from left-over whole blood samples based on the criteria for normal or dyslipidemia, and stored them at -20 °C until use. Then we selected 18 plasma samples for each normal, athero-risk and treated group using a metabolic disease cohort in which candidate subjects have participated. For classifying into three groups, we primarily relied on the records of physicians' comments, prescriptions, treatment history, lipid profiles and test results from medical equipment aimed at the diagnosis for atherosclerosis or cardiovascular disease. After collecting the final 54 plasma samples, we analyzed and compared the expression levels of miR-33a and ABCA1 at the plasma levels. In the comparison of plasma levels of the three groups, the miR-33a expression level of athero-risk group was 5.01-fold higher than that of normal group. Meanwhile, in the culture of foam cells transfected with anti-miR-33a oligonucleotides, the miR-33a level significantly decreased, while ABCA1 level significantly increased. The results suggest that enhanced expression of miR-33a might induce cholesterol accumulation and aggravate inflammation in vessel walls by suppressing the expression of ABCA1 in macrophages. Thus, plasma miR-33a can be considered as a candidate biomarker of atherosclerosis.

Differences in ABCA1 R219K Polymorphisms and Serum Indexes in Alzheimer and Parkinson Diseases in Northern China.

BACKGROUND ABCA1 R219K single-nucleotide polymorphisms (SNPs) was related to Alzheimer disease (AD) but not Parkinson disease (PD). Here, we analyzed the associations among ABCA1 R219K distribution, serum biomarkers, AD, and PD in a population in northern China. MATERIAL AND METHODS We used the Mini-Mental State Examination (MMSE) and the Hoehn and Yahr scale (H-Y) to evaluate AD and PD progression, separately. ABCA1 R219K was analyzed by matrix-assisted laser desorption ionization time of flight time mass spectrometry (MALDI-TOF-MS). Serum indexes were determined by enzyme-linked immunosorbent assay (ELISA). RESULTS ABCA1 R219K RR+RK genotype frequency in AD and PD patients was lower than that in normal controls (NC), while ABCA1 R219K KK genotype frequency was significantly higher. ABCA1 R219K RR genotype frequency in AD patients and NC was lower than that in PD patients, while ABCA1 R219K RK+KK genotype frequency was significantly higher. ABCA1 R219K RR genotype was positively correlated to MMSE value in AD patients, while ABCA1 R219K KK genotype was negatively correlated to H-Y value in PD patients. Serum factors were significantly different among AD and PD patients and NC. Serum ABCA1, ApoA1, ApoA2, ApoB, HDL, TC, IL-1ß, IL-6, and TNF-α were significantly different between AD and PD patients. CONCLUSIONS ABCA1 R219K R allele was the risk factor inducing abnormal serum levels of ApoA2, LDL, and TG in AD patients, and abnormal levels of serum ABCA1, HDL, IL-1b, IL-6, and TNF-α in PD patients, while ABCA1 R219K K allele was the risk factor inducing lower ABCA1 in AD patients. IL-1ß, IL-6, and TNF-α were negatively correlated to MMSE in AD patients but positively correlated to H-Y in PD patients, while HDL was positively related to H-Y in PD patients.

Hematopoietic ABCA1 deletion promotes monocytosis and worsens diet-induced insulin resistance in mice.

Low-grade chronic inflammation plays an important role in the pathogenesis of obesity-induced insulin resistance. ABCA1 is essential for reverse cholesterol transport and HDL synthesis, and protects against macrophage inflammation. In the present study, the effects of ABCA1 deficiency in hematopoietic cells on diet-induced inflammation and insulin resistance were tested in vivo using bone marrow transplanted (BMT)-WT and BMT-ABCA1(-/-) mice. When challenged with a high-fat high-carbohydrate diabetogenic diet with added cholesterol (HFHSC), BMT-ABCA1(-/-) mice displayed enhanced insulin resistance and impaired glucose tolerance as compared with BMT-WT mice. The worsened insulin resistance and impaired glucose tolerance in BMT-ABCA1(-/-) mice were accompanied by increased macrophage accumulation and inflammation in adipose tissue and liver. Moreover, BMT-ABCA1(-/-) mice had significantly higher hematopoietic stem cell proliferation, myeloid cell expansion, and monocytosis when challenged with the HFHSC diet. In vitro studies indicated that macrophages from ABCA1(-/-) mice showed significantly increased inflammatory responses induced by saturated fatty acids. Taken together, these studies point to an important role for hematopoietic ABCA1 in modulating a feed-forward mechanism in obesity such that inflamed tissue macrophages stimulate the production of more monocytes, leading to an exacerbation of inflammation and associated disease processes.

[The hormonal and metabolic characteristics of children of dispensarization observation group of "frequently ill children"].

In spite of long-standing interest of researchers to problem of high susceptibility of frequently ill children to agents of respiratory diseases, so far no pathogenic mechanisms of this phenomenon were established. Therefore, selection of appropriate techniques of prevention of frequent respiratory diseases is complicated. Previously, the key role of cortisol and lipid-transferring system of blood in pathologic process was demonstrated. However, the assumption was expressed concerning heterogeneity of group of frequently ill children in content of cortisol - possibly conditioned by polymorphism of receptors to cortisol and as a sequence alteration of their quantity and sensitivity to this hormone. In turn, occurring imbalance between amount of cortisol and receptors is able to result in large specter of metabolic and immunological alterations. The purpose of this study was investigation of content of cortisol in blood, amount of its nuclear receptors in leukocytes and also lipid-transferring system of blood of frequently ill children examined in autumn in inter-morbid period. The statistical analysis of received results permits stating that group of frequently ill children is heterogeneous and is presented by two sub-groups with reliably differing by level of cortisol and ratio cortisol/ receptors to cortisol. This phenomenon cab be conditioned by polymorphism of genes coding nuclear receptors to cortisol, ATP- binding cassette transporter, lecithin cholesterol acyltransferase, scavenger-receptors. The step-by-step discriminant analysis with development of discriminant diagnostic model detected cortisol, cholesterol of high density lipoproteins and cholesterol of low density lipoproteins as valuable factors being active participants of development ofphenomenon of frequently ill children.

HDL-apolipoprotein A-I exchange is independently associated with cholesterol efflux capacity.

HDL is the primary mediator of cholesterol mobilization from the periphery to the liver via reverse cholesterol transport (RCT). A critical first step in this process is the uptake of cholesterol from lipid-loaded macrophages by HDL, a function of HDL inversely associated with prevalent and incident cardiovascular disease. We hypothesized that the dynamic ability of HDL to undergo remodeling and exchange of apoA-I is an important and potentially rate-limiting aspect of RCT. In this study, we investigated the relationship between HDL-apoA-I exchange (HAE) and serum HDL cholesterol (HDL-C) efflux capacity. We compared HAE to the total and ABCA1-specific cholesterol efflux capacity of 77 subjects. We found that HAE was highly correlated with both total (r = 0.69, P < 0.0001) and ABCA1-specific (r = 0.47, P < 0.0001) efflux, and this relationship remained significant after adjustment for HDL-C or apoA-I. Multivariate models of sterol efflux capacity indicated that HAE accounted for approximately 25% of the model variance for both total and ABCA1-specific efflux. We conclude that the ability of HDL to exchange apoA-I and remodel, as measured by HAE, is a significant contributor to serum HDL efflux capacity, independent of HDL-C and apoA-I, indicating that HDL dynamics are an important factor in cholesterol efflux capacity and likely RCT.

Targeted next-generation sequencing to diagnose disorders of HDL cholesterol.

A low level of HDL cholesterol (HDL-C) is a common clinical scenario and an important marker for increased cardiovascular risk. Many patients with very low or very high HDL-C have a rare mutation in one of several genes, but identification of the molecular abnormality in patients with extreme HDL-C is rarely performed in clinical practice. We investigated the accuracy and diagnostic yield of a targeted next-generation sequencing (NGS) assay for extreme levels of HDL-C. We developed a targeted NGS panel to capture the exons, intron/exon boundaries, and untranslated regions of 26 genes with highly penetrant effects on plasma lipid levels. We sequenced 141 patients with extreme HDL-C levels and prioritized variants in accordance with medical genetics guidelines. We identified 35 pathogenic and probably pathogenic variants in HDL genes, including 21 novel variants, and performed functional validation on a subset of these. Overall, a molecular diagnosis was established in 35.9% of patients with low HDL-C and 5.2% with high HDL-C, and all prioritized variants identified by NGS were confirmed by Sanger sequencing. Our results suggest that a molecular diagnosis can be identified in a substantial proportion of patients with low HDL-C using targeted NGS.

Importance of evaluating cell cholesterol influx with efflux in determining the impact of human serum on cholesterol metabolism and atherosclerosis.

OBJECTIVE: Cholesterol efflux relates to cardiovascular disease but cannot predict cellular cholesterol mass changes. We asked whether influx and net flux assays provide additional insights. APPROACH AND RESULTS: Adapt a bidirectional flux assay to cells where efflux has clinical correlates and examine the association of influx, efflux, and net flux to serum triglycerides (TGs). Apolipoprotein B-depleted (high-density lipoprotein-fraction) serum from individuals with unfavorable lipids (median [interquartile range]; high-density lipoprotein-cholesterol=39 [32-42], low-density lipoprotein-cholesterol=109 [97-137], TGs=258 [184-335] mg/dL; n=13) promoted greater ATP-binding cassette transporter A1-mediated [1,2-(3H)] cholesterol efflux (3.8±0.3%/4 hour versus 1.2±0.4%/4 hour; P<0.0001) from cyclic 3',5'-amp(CTP-amp)-treated J774 macrophages than from individuals with favorable lipids (high-density lipoprotein-cholesterol=72 [58-88], low-density lipoprotein-cholesterol=111 [97-131], TGs=65 [56-69] mg/dL; n=10). Thus, high TGs associated with more ATP-binding cassette transporter A1 acceptors. Efflux of cholesterol mass (µg free cholesterol/mg cell protein per 8 hour) to serum was also higher (7.06±0.33 versus 5.83±0.48; P=0.04). However, whole sera from individuals with unfavorable lipids promoted more influx (5.14±0.65 versus 2.48±0.85; P=0.02) and lower net release of cholesterol mass (1.93±0.46 versus 3.36±0.47; P=0.04). The pattern differed when mass flux was measured using apolipoprotein B-depleted serum rather than serum. Although individuals with favorable lipids tended to have greater influx than those with unfavorable lipids, efflux to apolipoprotein B-depleted serum was markedly higher (6.81±0.04 versus 2.62±0.14; P<0.0001), resulting in an efflux:influx ratio of ≈3-fold. Thus both serum and apolipoprotein B-depleted serum from individuals with favorable lipids promoted greater net cholesterol mass release despite increased ATP-binding cassette transporter A1-mediated efflux in samples of individuals with high TGs/unfavorable lipids. CONCLUSIONS: When considering the efficiency of serum specimens to modulate cell cholesterol content, both influx and efflux need to be measured.

CSL112 enhances biomarkers of reverse cholesterol transport after single and multiple infusions in healthy subjects.

OBJECTIVE: The ability of apolipoprotein A-I (apoA-I) to transport cholesterol from atherosclerotic plaque is thought to underlie its inverse correlation with cardiovascular risk. To gauge the potential of infused apoA-I to transport cholesterol, we quantified cholesterol transport markers in human subjects infused with a novel formulation of apoA-I (CSL112). APPROACH AND RESULTS: CSL112 was infused into human subjects in single (57 subjects) and multiple (36 subjects) ascending dose trials. Pharmacokinetic and biomarker assessments were conducted before and after infusions. CSL112 caused an immediate, up to 3-fold elevation of apoA-I and subsequent movement of tissue cholesterol into plasma. Cholesterol appeared first as unesterified cholesterol in the high-density lipoprotein (HDL) fraction and was promptly esterified by lecithin cholesterol acyltransferase. HDL cholesterol increased up to 81±16.5%. Underlying this movement of cholesterol was an immediate and strong rise in the ability of plasma to promote cholesterol efflux from cells ex vivo. CSL112 had its greatest impact on the fraction of efflux mediated by ATP-binding cassette transporter A1 (ABCA1), a cholesterol transporter induced in cholesterol-loaded tissues such as plaque. ABCA1-dependent efflux capacity increased ≤630±421% and total efflux capacity by ≤192±40%. In keeping with this finding, we observed a profound rise in very small HDL, also known as preß1-HDL, the preferred substrate for ABCA1. Very small HDL increased ≤3596±941%. Elevations in apoA-I, cholesterol efflux, and very small HDL were dose-proportional over a wide range. No significant changes in atherogenic lipids were observed at any dose. CONCLUSIONS: Infusion of CSL112 elevates the ability of plasma to withdraw cholesterol from cells. Preferential elevation of ABCA1-dependent efflux may target atherosclerotic plaque for cholesterol removal, making CSL112 a promising candidate therapy for acute coronary syndrome.

Lower Apo A-I and lower HDL-C levels are associated with higher intermediate CD14++CD16+ monocyte counts that predict cardiovascular events in chronic kidney disease.

OBJECTIVE: Patients with chronic kidney disease (CKD) display impaired cholesterol efflux capacity and elevated CD14(++)CD16(+) monocyte counts. In mice, dysfunctional cholesterol efflux causes monocytosis. It is unknown whether cholesterol efflux capacity and monocyte subsets are associated in CKD. APPROACH AND RESULTS: In 438 patients with CKD, mediators of cholesterol efflux capacity (high-density lipoprotein cholesterol/apolipoprotein A-I) and monocyte subsets were analyzed as predictors of cardiovascular events. Monocyte subset-specific intracellular lipid content, CD36, CD68, and ABCA1 were measured in a subgroup. Experimentally, we analyzed subset-specific cholesterol efflux capacity and response to oxidized low-density lipoprotein cholesterol stimulation in CKD. Epidemiologically, both low Apo-I and low high-density lipoprotein cholesterol were associated with high CD14(++)CD16(+) monocyte counts in linear regression analyses (apolipoprotein A-I: ß=-0.171; P<0.001; high-density lipoprotein cholesterol: ß=-0.138; P=0.005), but not with counts of other monocyte subsets. In contrast to apolipoprotein A-I or high-density lipoprotein cholesterol, higher CD14(++)CD16(+) monocyte counts independently predicted cardiovascular events (hazard ratio per increase of 1 cell/µL: 1.011 [1.003-1.020]; P=0.007). Experimentally, CD14(++)CD16(+) monocytes demonstrated preferential lipid accumulation, high CD36, CD68, and low ABCA1 expression and, consequently, displayed low cholesterol efflux capacity, avid oxidized low-density lipoprotein cholesterol uptake, and potent intracellular interleukin-6, interleukin-1ß, and tumor necrosis factor-α production. CONCLUSIONS: Taken together, mediators of cholesterol efflux are associated with CD14(++)CD16(+) monocyte counts, which independently predict adverse outcome in CKD.

Liver X receptor (LXR) partial agonists: biaryl pyrazoles and imidazoles displaying a preference for LXRß.

A series of biaryl pyrazole and imidazole Liver X Receptor (LXR) partial agonists has been synthesized displaying LXRß selectivity. The LXRß selective partial agonist 18 was identified with potent induction of ATP binding transporters ABCA1 and ABCG1 in human whole blood (EC50=1.2µM, 55% efficacy). In mice 18 displayed peripheral induction of ABCA1 at 3 and 10mpk doses with no significant elevation of plasma or hepatic triglycerides at these doses, showing an improved profile compared to a full pan-agonist.

Mouse models of disturbed HDL metabolism.

High-density lipoprotein (HDL) is considered to be an anti-atherogenic lipoprotein moiety. Generation of genetically modified (total body and tissue-specific knockout) mouse models has significantly contributed to our understanding of HDL function. Here we will review data from knockout mouse studies on the importance of HDL's major alipoprotein apoA-I, the ABC transporters A1 and G1, lecithin:cholesterol acyltransferase, phospholipid transfer protein, and scavenger receptor BI for HDL's metabolism and its protection against atherosclerosis in mice. The initial generation and maturation of HDL particles as well as the selective delivery of its cholesterol to the liver are essential parameters in the life cycle of HDL. Detrimental atherosclerosis effects observed in response to HDL deficiency in mice cannot be solely attributed to the low HDL levels per se, as the low HDL levels are in most models paralleled by changes in non-HDL-cholesterol levels. However, the cholesterol efflux function of HDL is of critical importance to overcome foam cell formation and the development of atherosclerotic lesions in mice. Although HDL is predominantly studied for its atheroprotective action, the mouse data also suggest an essential role for HDL as cholesterol donor for steroidogenic tissues, including the adrenals and ovaries. Furthermore, it appears that a relevant interaction exists between HDL-mediated cellular cholesterol efflux and the susceptibility to inflammation, which (1) provides strong support for the novel concept that inflammation and metabolism are intertwining biological processes and (2) identifies the efflux function of HDL as putative therapeutic target also in other inflammatory diseases than atherosclerosis.

Low Serum Levels of ABCA1, an ATP-Binding Cassette Transporter, Are Predictive of Preeclampsia.

Preeclampsia is a pregnancy-specific disorder characterized by hypertension and proteinuria, but the exact cause of preeclamptic hypertension remains unknown. ATP-binding cassette subfamily A member 1 (ABCA1) reverses cholesterol transport and eliminates excess cholesterol from tissues, whereas higher levels of cholesterol may lead to hypertension. Thus, ABCA1 affects the blood lipid profile. We have hypothesized that serum ABCA1 levels may influence the onset of hypertension and increase the risk of preeclampsia. To test this hypothesis, we measured serum ABCA1 levels in 50 normal pregnancies, 36 preeclamptic pregnancies, and 24 small-for-gestational-age (SGA) pregnancies during three trimesters. We also measured the concentrations of serum ABCA1 in non-pregnant women (n = 60), showing its normal ranges of 0.16 to 0.52 ng/ml. Importantly, the serum levels of ABCA1 were similar among non-pregnant women, normal pregnancies and SGA pregnancies. In contrast, the serum ABCA1 levels were significantly lower in preeclamptic pregnancies (0.06 ± 0.03 ng/ml) than those in non-pregnant women, and normal and SGA pregnancies (P < 0.05). Low serum ABCA1 levels were associated with the increases in the concentrations of blood lipid (low density lipoprotein cholesterol, total cholesterol and triglycerides) and with the decrease in the concentration of high-density lipoprotein cholesterol (P < 0.01), all of which may contribute to the onset of hypertension and eventually preeclampsia. Moreover, the preeclamptic pregnancy was diagnosed with high sensitivity from the nulliparous pregnancies if the cutoff value for serum ABCA1 was 0.06 ng/ml. Thus, low serum levels of ABCA1 are predictive of preeclampsia.

miR-28-5p Involved in LXR-ABCA1 Pathway is Increased in the Plasma of Unstable Angina Patients.

BACKGROUND: Previous studies confirmed that the intronic miRNAs participated in regulating host gene-primed biological processes. The coordinated roles of miR-28 with its host gene, LIM domain lipoma-preferred partner (LPP), remain unknown in atherosclerosis. METHODS: In this study, we determined to assess circulating levels of miR-28-5p in unstable angina patients, compared with age- and sex- matched control subjects by quantitative PCR. Furthermore, we attempted to explore whether miR-28-5p could influence the expression of ATP-binding cassette transporter A1 (ABCA1) and liver X receptor (LXR), major mediators of high density lipoprotein (HDL) synthesis and transportation in hepatic cells and macrophages. RESULTS: It was found that plasma levels of miR-28-5p were significantly increased in unstable angina patients with or without type 2 diabetes mellitus. Notably, miR-28-5p upregulated ABCA1 expression at transcription and translation levels, strongly correlated with translational activation of LXRα in HepG2 and THP-1-derived macrophages. CONCLUSIONS: Our findings suggest that circulating miR-28-5p, involved in LXRα-ABCA1 pathway, may be a potential biomarker for diagnosis and prognosis of unstable angina.