ABCG1 mRNA Research Articles

Oxidative Stress, Inflammation, and Altered Lymphocyte E-NTPDase Are Implicated in Acute Dyslipidemia in Rats: Protective Role of Arbutin

Background/Objectives: Dyslipidemia is frequently linked to various disorders, and its clinical relevance is now recognized. The role of inflammation and oxidative stress (OS) in dyslipidemia has been acknowledged. This study assessed the potential of arbutin (ARB) to prevent dyslipidemia and its associated OS and inflammation in rats with acute hyperlipidemia. Methods: Rats received ARB orally for 14 days and a single intraperitoneal injection of poloxamer-407 on day 15. Results: Poloxamer-407 elevated circulating cholesterol (CHOL), triglycerides (TG), very low-density lipoprotein (vLDL), and LDL, and reduced high-density lipoprotein (HDL)-C and lipoprotein lipase (LPL). ARB ameliorated the circulating lipids and LPL, and suppressed 3-hydroxy-3-methylglutaryl CoA reductase (HMGCR) in rat liver and in vitro. Fatty acid synthase (FAS) in rat liver and its in vitro activity were suppressed by ARB, which also upregulated the LDL receptor (LDL-R) and ABCA1, and had no effect on ABCG5 and ABCG8 mRNA. ARB ameliorated liver malondialdehyde and nitric oxide and enhanced antioxidants in rats with dyslipidemia. Liver NF-κB p65 and blood inflammatory cytokines were increased in dyslipidemic rats, effects that were reversed by ARB. Moreover, ARB effectively suppressed lymphocyte E-NTPDase and E-ADA activities in dyslipidemic rats. The biochemical findings were supported by in silico data showing the affinity of ARB to bind LDL-R PCSK9 binding domain, HMGCR, FAS, and E-NTPDase. Conclusions: ARB possessed anti-dyslipidemia, anti-inflammatory, and antioxidant effects mediated via the modulation of CHOL and TG synthesis, LPL, lymphocyte E-NTPDase and E-ADA, and cytokine release in rats. Thus, ARB could be an effective agent to attenuate dyslipidemia and its associated OS and inflammation, pending further studies as well as clinical trials.

The Lian-Dou-Qing-Mai Formula activates the PPARγ-LXRα-ABCA1/ABCG1 pathway by regulating IL-10, leading to the promotion of cholesterol efflux and a reduction in atherosclerotic plaques.

To observe the effect of the Lian-Dou-Qing-Mai (LDQM) formula on lipid metabolism in mice and explore its mechanism from the perspective of regulating the PPARγ/LXRα/ABCA1 signaling pathway. THP-1 cells were induced to transform into foam cells with ox-LDL. Atherosclerosis (AS) models were constructed using a high-fat diet in ApoE-/- mice. Detection kits were used to evaluate triglyceride (TG) and total cholesterol (TC) content; TNF-α, MCP-1, MMP-9, TMP-1, PPARγ, LXRα, ABCA1, and ABCG1 mRNA and protein expression were identified using real-time PCR and western blot. Interleukin-10 (IL-10) blood levels were measured using an enzyme-linked immunosorbent assay (ELISA), and aortic plaque development and lipid deposition were seen using hematoxylin and eosin (HE) and oil red O staining, respectively. In the cell model, LDQM could inhibit the formation of THP-1 macrophage-derived foam cells and the expression of inflammatory factors, promote macrophage cholesterol efflux, increase the expression of IL-10, and activate the PPARγ-LXRα-ABCA1/ABCG1 pathway. Additional IL-10 treatment further promotes LDQM-induced cholesterol efflux in THP-1 cells; in In vivo models, LDQM inhibited the area of atherosclerotic lesions, aortic lipid deposition, and inflammation levels in ApoE-/- mice through IL-10, and activated the expression level of the PPARγ-LXRα-ABCA1/ABCG1 pathway. LDQM may affect the PPARγ/LXRα/ABCA1 signaling pathway through IL-10, regulate lipid metabolism, reduce serum inflammatory expression and lipid deposition, and improve the formation of atheroplaques.

The Expression of Genes Related to Reverse Cholesterol Transport and Leptin Receptor Pathways in Peripheral Blood Mononuclear Cells Are Decreased in Morbid Obesity and Related to Liver Function.

Obesity is frequently accompanied by non-alcoholic fatty liver disease (NAFLD). These two diseases are associated with altered lipid metabolism, in which reverse cholesterol transport (LXRα/ABCA1/ABCG1) and leptin response (leptin receptor (Ob-Rb)/Sam68) are involved. The two pathways were evaluated in peripheral blood mononuclear cells (PBMCs) from 86 patients with morbid obesity (MO) before and six months after Roux-en-Y gastric bypass (RYGB) and 38 non-obese subjects. In the LXRα pathway, LXRα, ABCA1, and ABCG1 mRNA expressions were decreased in MO compared to non-obese subjects (p < 0.001, respectively). Ob-Rb was decreased (p < 0.001), whereas Sam68 was increased (p < 0.001) in MO. RYGB did not change mRNA gene expressions. In the MO group, the LXRα pathway (LXRα/ABCA1/ABCG1) negatively correlated with obesity-related variables (weight, body mass index, and hip), inflammation (C-reactive protein), and liver function (alanine-aminotransferase, alkaline phosphatase, and fatty liver index), and positively with serum albumin. In the Ob-R pathway, Ob-Rb and Sam68 negatively correlated with alanine-aminotransferase and positively with albumin. The alteration of LXRα and Ob-R pathways may play an important role in NAFLD development in MO. It is possible that MO patients may require more than 6 months following RYBGB to normalize gene expression related to reverse cholesterol transport or leptin responsiveness.

Extracellular Vesicles Secreted by Adipose Tissue during Obesity and Type 2 Diabetes Mellitus Influence Reverse Cholesterol Transport-Related Gene Expression in Human Macrophages.

Obesity is a risk factor for type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). Adipose tissue (AT) extracellular vesicles (EVs) could play a role in obesity and T2DM associated CVD progression via the influence of their specific cargo on gene expression in recipient cells. The aim of this work was to evaluate the effects of AT EVs of patients with obesity with/without T2DM on reverse cholesterol transport (RCT)-related gene expression in human monocyte-derived macrophages (MDMs) from healthy donors. AT EVs were obtained after ex vivo cultivation of visceral and subcutaneous AT (VAT and SAT, respectively). ABCA1, ABCG1, PPARG, LXRβ (NR1H2), and LXRα (NR1H3) mRNA levels in MDMs as well as in origine AT were determined by a real-time PCR. T2DM VAT and SAT EVs induced ABCG1 gene expression whereas LXRα and PPARG mRNA levels were simultaneously downregulated. PPARG mRNA levels also decreased in the presence of VAT EVs of obese patients without T2DM. In contrast ABCA1 and LXRβ mRNA levels tended to increase with the addition of obese AT EVs. Thus, AT EVs can influence RCT gene expression in MDMs during obesity, and the effects are dependent on T2DM status.

Abstract 3072: GDF15 Represses The Interferon Response Early In Vascular Senescence

Senescent cells have been identified as major contributors of the progression of vascular diseases including atherosclerosis by increasing the senescence-associated secretory phenotype (SASP) and dysregulating vascular cells. Notably, senescence and the SASP can contribute to plaque rupture and atherosclerotic progression by promoting inflammation and plaque vulnerability. A time course microarray analysis of vascular smooth muscle cell (VSMC) senescence revealed p53-regulated GDF15 mRNA was increased early and remained elevated throughout senescence. Notably, GDF15 has been implicated as a biomarker for cardiovascular disease mortality and is part of the conserved SASP across cell types and tissues. Interestingly, intracellular or secreted GDF15 protein levels were increased in monkeys fed a high-fat diet or in mice fed a high-fat diet and in individuals with high Framingham risk scores, respectively. We sought to identify the role of GDF15 in senescent VSMCs. Using CRISPRi, we silenced GDF15 during early senescence and performed RNA-sequencing. Pathway analysis revealed a enrichment in interferon signaling with the loss of GDF15. Coinciding with the increase in interferon signaling, phosphorylation of STAT1 and CREB were increased by loss of GDF15 in early senescence, aiding in the elevation of interferon expression. Given the role of interferons in communication and the prominence of macrophages in atherosclerosis, we tested the effects of conditioned media, derived from either proliferating or senescent VSMCs, on the activation and the expression of scavenger receptors on human macrophages. Senescent conditioned media increased expression of ABCG1 , CD36 , LOX-1 , SCARF1 , and GDF15 mRNA as well as TNFα and CCL2 secretion in macrophages. We propose that elevated GDF15 levels in early senescence suppress interferon signaling, thus preventing macrophage chemotaxis and in turn leading to the accumulation of senescent cells in the vasculature. Thus, disrupting the senescent VSMC-macrophage communication through secreted proteins may offer promising avenues of therapeutic development to prevent or improve inflammatory vascular diseases.

Danggui Shaoyao powder improves hepatic lipid metabolism in atherosclerosis mice via PPARγ-LXRα-ABCA1 pathway regulation

ObjectiveTo observe the effects of Danggui Shaoyao powder (DSP) on hepatic lipid metabolism and further explore its mechanism of action by peroxisome proliferator-activated receptor (PPARγ)-liver X receptor (LXRα)-adenosine triphosphate (ATP)-binding cassette transporter A1 (ABCA1) pathway regulation. MethodsEight C57BL/6J male mice were selected as the control group, and 24 ApoE−/− male mice were randomly divided into the atherosclerosis model (AS) group, atorvastatin calcium (AC) group, and DSP group (n = 8 each group). To establish an AS model, ApoE−/− mice were fed a high-fat diet for 16 weeks. Pathologic changes in the aortic vasculature and liver were identified using Oil Red O staining. Triglyceride (TG), cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) levels were determined in the livers using a single-reagent GPO-PAP method. Fluorescence quantitative polymerase chain reaction and western blot were used to observe and evaluate the mRNA and protein expression of the PPARγ-LXRα-ABCA1 intermediates in the liver. ResultsAfter 16 weeks of a high-fat diet, ApoE−/− mice showed more Oil Red O staining in the aorta and liver compared to the CONT group. Compared to the AS group, the DSP and AC treatment reduced aortic plaque and hepatic lipid deposition to varying degrees. Furthermore, DSP significantly reduced the hepatic lipid area in ApoE−/− mice (P < .001) and decreased the levels of TG, TC, and LDL-C in liver (P < .001, P = .027, P < .001, respectively). DSP also significantly increased the levels of PPARγ, LXRα, ABCA1, and ABCG1 mRNA expression, as well as the PPARγ, LXRα, ABCA1, and ABCG1 protein expression in liver. ConclusionDSP improved hepatic lipid metabolism via PPARγ-LXRα-ABCA1 pathway modulation for AS treatment.

Cholesterol deficiency as a mechanism for autism: A valproic acid model.

Dysregulated cholesterol metabolism represents an increasingly recognized feature of autism spectrum disorder (ASD). Children with fetal valproate syndrome caused by prenatal exposure to valproic acid (VPA), an anti-epileptic and mood-stabilizing drug, have a higher incidence of developing ASD. However, the role of VPA in cholesterol homeostasis in neurons and microglial cells remains unclear. Therefore, we examined the effect of VPA exposure on regulation of cholesterol homeostasis in the human microglial clone 3 (HMC3) cell line and the human neuroblastoma cell line SH-SY5Y. HMC3 and SH-SY5Y cells were each incubated in increasing concentrations of VPA, followed by quantification of mRNA and protein expression of cholesterol transporters and cholesterol metabolizing enzymes. Cholesterol efflux was evaluated using colorimetric assays. We found that VPA treatment in HMC3 cells significantly reduced ABCA1 mRNA, but increased ABCG1 and CD36 mRNA levels in a dose-dependent manner. However, ABCA1 and ABCG1 protein levels were reduced by VPA in HMC3. Furthermore, similar experiments in SH-SY5Y cells showed increased mRNA levels for ABCA1, ABCG1, CD36, and 27-hydroxylase with VPA treatment. VPA exposure significantly reduced protein levels of ABCA1 in a dose-dependent manner, but increased the ABCG1 protein level at the highest dose in SH-SY5Y cells. In addition, VPA treatment significantly increased cholesterol efflux in SH-SY5Y, but had no impact on efflux in HMC3. VPA differentially controls the expression of ABCA1 and ABCG1, but regulation at the transcriptional and translational levels are not consistent and changes in the expression of these genes do not correlate with cholesterol efflux in vitro.

Liver-Specific Bmal1 Depletion Reverses the Beneficial Effects of Nobiletin on Liver Cholesterol Homeostasis in Mice Fed with High-Fat Diet.

Nobiletin (NOB), a naturally occurring small-molecule compound abundant in citrus peels, has displayed potential lipid-lowering and circadian-enhancing properties in preclinical studies. However, the requirement of specific clock genes for the beneficial effects of NOB is not well understood. In the current study, mice with a liver-specific deletion of the core clock component, Bmal1-Bmal1LKO-were fed a high-fat diet (HFD) ad libitum for eight weeks, while NOB (200 mg/kg) was administered by daily oral gavage from the fifth week and throughout the last four weeks. NOB decreased liver triglyceride (TG) alongside the decreasing mRNA levels of de novo lipogenesis (DNL) genes in both Bmal1flox/flox and Bmal1LKO mice. NOB increased serum very low-density lipoprotein (VLDL) levels in Bmal1LKO mice, which was consistent with higher liver Shp and lower Mttp mRNA expression levels, the key genes that facilitate VLDL assembly and secretion. NOB decreased liver and serum cholesterol levels in the Bmal1flox/flox mice, consistent with lower Hmgcr and higher Cyp7a1, Cyp8b1, Gata4 and Abcg5 mRNA levels in the liver. In contrast, in the Bmal1LKO mice, NOB increased Hmgcr mRNA levels and had no effect on the above-mentioned genes related to bile acid synthesis and cholesterol excretion, which might contribute to the elevation of liver and serum cholesterol levels in NOB-treated Bmal1LKO mice. NOB inhibited hepatic DNL and decreased liver TG levels in HFD-fed mice independently of liver Bmal1, whereas liver-specific Bmal1 depletion reversed the beneficial effects of NOB on liver cholesterol homeostasis. The complex interactions between NOB, the circadian clock and lipid metabolism in the liver warrant further research.

AdipoRon Effect on Expression of Lipid Metabolism Genes in Cultured Human Primary Macrophages

Atherosclerosis is characterized by excessive uptake of cholesterol-rich low-density lipoprotein (LDL) by vascular wall macrophages. The macrophages are transformed into foam cells, lipids accumulate in the intima of arteries, atherosclerotic plaques arise, and cardiovascular diseases develop. Adiponectin is an adipose tissue adipokine and possess anti-atherogenic and anti-inflammatory activities, which are mediated by adiponectin binding to its receptors AdipoR1 and AdipoR2. To exert its anti-atherogenic effect, adiponectin may regulate the reverse cholesterol transport and prevent foam cells formation. The small-molecule adiponectin receptor agonist AdipoRon was assumed to modulate expression of reverse cholesterol transport and inflammation genes in human macrophages. Several AdipoRon concentrations (0, 5, 10, and 20 μM) were tested for effect on expression of the lipid metabolism genes ABCA1, ABCG1, APOA1, NR1H3 (LXRα), NR1H2 (LXRβ), PPARG, and ACAT1 and the inflammation genes IL6, TNFA, and TLR4 in cultured human primary macrophages and the THP-1 macrophage cell line. Cell viability was measured using the MTS assay. ABCA1, ABCG1, APOA1, NR1H3, NR1H2, PPARG, ACAT1, IL6, TNFA, and TLR4 mRNA levels in human primary macrophages were assessed by real-time PCR. The PPARG and ABCA1 relative mRNA levels were found to increase in human primary macrophages treated with 5 or 10 μM AdipoRon for 24 h. A higher AdipoRon concentration (20 μM) was cytotoxic to macrophages, especially THP-1 cells. The effect of AdipoRon on human macrophages and potential adiponectin receptor agonists are of interest to study in view of the need to develop new approaches to atherosclerosis prevention and treatment.

Caffeic acid protects against atherosclerotic lesions and cognitive decline in ApoE−/− mice

Caffeic acid has been indicated to benefit cholesterol balance, but the effect of pure caffeic acid on atherosclerosis in vivo has not been tested. Given that atherosclerosis and Alzheimer's disease share common features including distracted lipid balance and chronic inflammation, the concurrent effects of caffeic acid on atherosclerotic lesions and cognitive decline were explored here by using the ApoE−/− mice model. A two months' administration of 20 mg/kg caffeic acid or saline was given once two days intraperitoneally to 5-month-old female ApoE−/− mice. We found that the caffeic acid treatment reduced the atherosclerotic lesions in the whole aorta and aortic sinus of the resulting 7-month-old ApoE−/− mice by roughly 50%, compared with the saline control. Meanwhile, the cognitive decline of treated mice were significantly alleviated, as measured by Y-maze and Morris water maze tasks. A reduced accumulation of β-amyloid in the hippocampus was also observed. These effects were associated with elevated serum HDL-c concentration, upregulated ABCA1 and ABCG1 mRNA levels, as well as decrease local inflammation and reduced levels of serum pro-inflammatory cytokines including TNF-α, IL-6 and MCP-1. These obtained results suggested the preventive and therapeutic potential of caffeic acid against atherosclerosis and Alzheimer's disease during aging.

Systematic Construction and Validation of a Novel Macrophage Differentiation-Associated Prognostic Model for Clear Cell Renal Cell Carcinoma.

Background: Clear cell renal cell carcinoma (ccRCC) is a malignant tumor of the human urinary system. Macrophage differentiation is associated with tumorigenesis. Therefore, exploring the prognostic value of macrophage differentiation–associated genes (MDGs) may contribute to better clinical management of ccRCC patients. Methods: The RNA sequence data of ccRCC were obtained from The Cancer Genome Atlas (TCGA) database. Differentially expressed MDGs were unveiled in ccRCC and normal samples. The prognostic model was established according to the univariate and multivariate Cox regression analyses. By combining clinico-pathological features and prognostic genes, a nomogram was established to predict individual survival probability. The Tumor Immune Estimation Resource (TIMER) database was utilized to analyze the correlation between prognostic genes and immune infiltrating cells. Eventually, the mRNA and protein expression levels of prognostic genes were verified. Results: A total of 52 differentially expressed prognosis-related MDGs were identified in ccRCC. Afterward, a six-gene prognostic model (ABCG1, KDF1, KITLG, TGFA, HAVCR2, and CD14) was constructed through the Cox analysis. The overall survival in the high-risk group was relatively poor. Moreover, the risk score was identified as an independent prognostic factor. We constructed a prognostic nomogram with a well-fitted calibration curve based on risk score and clinical data. Furthermore, the prognostic genes were significantly related to the level of immune cell infiltration including B cells, CD8+T cells, CD4+T cells, macrophages, neutrophils, and dendritic cells. Finally, the mRNA expression of prognostic genes in clinical ccRCC tissues showed that the ABCG1, HAVCR2, CD14, and TGFA mRNA in tumor samples were increased compared with the adjacent control tissue samples, while KDF1 and KITLG were decreased, which was consistent with the verification results in the GSE53757. Conclusion: In conclusion, this study identified and validated a macrophage differentiation–associated prognostic model for ccRCC that could be used to predict the outcomes of the ccRCC patients.

Expression patterns of genes in steroidogenic, cholesterol uptake, and liver x receptor-mediated cholesterol efflux pathway regulating cholesterol homeostasis in natural and PGF2α induced luteolysis as well as early pregnancy in ovine corpus luteum

The aim was to evaluate the expression of genes of steroidogenic, cholesterol uptake, and liver X receptor (LXR) mediated cholesterol efflux pathway in ovine corpus luteum (CL) during natural and prostaglandin F2α (PGF2α) induced luteolysis and early pregnancy. For this study, two experiments were carried out 1); ewes were grouped into two sub-groups as cyclic 12 (C12, n = 4) and 16 (C16, n = 4) and pregnant 12 (P12, n = 4), 16 (P16, n = 4), and 22 (P22, n = 4). Additionally, 2) ewes were grouped into four groups following treatment of PGF2α, the duration of PGF2α challenge at 1 (PG1, n = 4), 4 (PG4, n = 4), and 16 (PG16, n = 4) hours on day 12 of the cycle was compared with 0 h. The corpus luteum tissue samples were collected on the corresponding estrus cycle and pregnancy days, and RNA was extracted using Trizol. mRNA expression levels of the steroidogenic (StAR, CYP11A1, and HSD3B1) and cholesterol uptake receptors (SCARB1 and LDLR) and LXR pathway (NR1H3, NR1H2, ABCA1, and ABCG1) were assessed using quantitative PCR (qPCR), and protein of LXR pathway was investigated using western blot. In-situ hybridization was used to detect mRNA localization. Steroidogenic and cholesterol uptake mRNAs were decreased in C16, while NR1H2 and ABCG1 were increased in C16, compared to C12. Steroidogenic and cholesterol uptake mRNA was greater in P16 than in C16. NR1H2 and ABCA1 protein expression were higher in P16 than in C16. LDLR mRNA was higher in P22 than in P12, while SCARB1 was higher in P16 than in P12. NR1H2 mRNA was greater in P22 than in P12. Steroidogenic and cholesterol uptake mRNA were decreased in PGF2α-induced luteolysis groups against C12. ABCG1 mRNA was higher in PG16 than in PG4 and PG1. The reduction of lipoprotein receptors rather than LXR-mediated reverse transport may contribute to the decline in progesterone (P4) in natural and functional luteolysis.

Expression of ABC transporters during syncytialization in preeclampsia.

Preeclampsia complicates 2-8% of pregnancies and is associated with prematurity and intrauterine growth restriction. Cholesterol and sterol transport is a key function of the placenta and it is elicited through ATP binding cassette (ABC) transporters. ABCA1 expression changes during trophoblast cell fusion, a process required to form the placental syncytium that enables maternal-fetal nutrient transfer. ABCA1 expression is dysregulated in preeclamptic placentas. But whether ABC transporters expression during trophoblast fusion is disrupted in preeclampsia remains unknown. We investigated if cholesterol and sterol ABC transporters are altered in term and preterm preeclampsia placentas and during human cytotrophoblast syncytialization. Human placental biopsies were collected from healthy term (≥37weeks; n=11) and term preeclamptic (≥36 6/7 weeks; n=8) and pre-term preeclamptic (28-35weeks; n=8) pregnancies. Both, protein and mRNA expression for ABCA1, ABCG1, ABCG5, and ABCG8 were evaluated. Primary cytotrophoblasts isolated from a subset of placentas were induced to syncytialize for 96h and ABCA1, ABCG1 and ABCG8 mRNA expression evaluated at 0h and 96h. Protein and gene expression of ABC transporters were not altered in preeclamptic placentas. In the healthy Term group, ABCA1 expression was similar before and after syncytialization. After 96h of syncytialization, mRNA expression of ABCA1 and ABCG1 increased significantly, while ABCG8 decreased significantly in term-preeclampsia, but not pre-term preeclampsia. While placental expression of ABCA1 and ABCG1 remained unaltered in term preeclampsia, the disruption in their dynamic expression pattern during cytotrophoblast syncytialization suggests that cholesterol transport may contribute to the pathophysiologic role of the placenta in preeclampsia.

The Effects of a High-Fat/Cholesterol Diet on the Intestine of Rats Were Attenuated by Sparassis latifolia Polysaccharides.

Sparassis latifolia polysaccharides can regulate lipids and cholesterol in serum and liver. However, little is known about the regulation mechanism of the polysaccharides on cholesterol metabolism and especially the causal relationship with gut microbiota regulation. This study will provide a theoretical basis for the cholesterol-lowering mechanism of S. latifolia polysaccharides and further development of functional foods. In this study, we investigated how the regulation mechanism of Sparassis latifolia polysaccharides affects intestinal cholesterol metabolism in high-fat and high-cholesterol diet-fed rats. Briefly, enzymatic colorimetric microplate assay was used to determine the concentration of faecal bile acid. Gas chromatography-mass spectrometry was used to detect the content of cholesterol and alcohol in faeces. Haematoxylin and eosin staining method was applied to observe the changes in the structure of the small intestine tissue. The related gene expressions in jejunum and ileum were detected by real-time fluorescent quantitative polymerase chain reaction. The related protein expressions in jejunum were studied by using Western blot. High-throughput sequencing was used to detect the intestinal flora changes of the caecal contents. Gas chromatography-mass spectrometry was applied to detect the concentration of short-chain fatty acids in the caecal content. The results showed that Sparassis latifolia polysaccharides could improve the intestinal morphological structure and physiological indices in rats fed high-fat and high-cholesterol diet. Moreover, it could improve intestinal cholesterol metabolism disorder induced by high-fat and high-cholesterol diets via the reduction of the expression of HMGCR, NPC1L1, ACAT2, MTP, ASBT and IBABP mRNA or protein, increasing ABCG8 mRNA expression. In addition, it could also increase the relative abundance of Bacteroides, Butyricicoccus, Parabacteroides, Parasutteerella and Alloprevotella and the short-chain fatty acid concentration, to comprehensively regulate the intestinal cholesterol metabolism. The metabolomics analysis found that Sparassis latifolia polysaccharides could affect lipid, carbohydrate and other related metabolites. Some biomarkers associated with cholesterol metabolism correlated significantly with the abundance of specific intestinal microbiota. These findings indicate that Sparassis latifolia polysaccharides could attenuate intestinal cholesterol metabolism disorder, correlating with modulating gut microbiota and improving host metabolism. They provide theoretical support for the development of Sparassis latifolia as a new food resource.

ABCA1 and ABCG1 DNA methylation in epicardial adipose tissue of patients with coronary artery disease

BackgroundRecent studies have focused on the potential role of epicardial adipose tissue (EAT) in the development of coronary artery disease (CAD). ABCA1 and ABCG1 transporters regulate cell cholesterol content and reverse cholesterol transport. We aimed to determine whether DNA methylation and mRNA levels of the ABCA1 and ABCG1 genes in EAT and subcutaneous adipose tissue (SAT) were associated with CAD.MethodsPaired EAT and SAT samples were collected from 82 patients undergoing elective cardiac surgery either for coronary artery bypass grafting (CAD group, N = 66) or valve surgery (NCAD group, N = 16). ABCA1 and ABCG1 mRNA levels in EAT and SAT samples were analyzed using real time polymerase chain reaction, ABCA1 protein levels in EAT samples were assessed by western blotting. ABCA1 and ABCG1 DNA methylation analysis was performed in 24 samples from the CAD group and 9 samples from the NCAD group via pyrosequencing.ResultsDNA methylation levels in the ABCA1 promoter and ABCG1 cg27243685 and cg06500161 CpG sites were higher in EAT samples from patients with CAD compared with NCAD (21.92% vs 10.81%, p = 0.003; 71.51% vs 68.42%, p = 0.024; 46.11% vs 37.79%, p = 0.016, respectively). In patients with CAD, ABCA1 and ABCG1 DNA methylation levels were higher in EAT than in SAT samples (p < 0.05). ABCA1 mRNA levels in EAT samples were reduced in the subgroup of patients with CAD and concomitant carotid artery disease or peripheral artery disease compared with the NCAD group (p = 0.024). ABCA1 protein levels in EAT samples tended to be lower in CAD patients than in the NCAD group (p = 0.053). DNA methylation levels at the ABCG1 cg27243685 site positively correlated with plasma triglyceride concentration (r = 0.510, p = 0.008), body mass index (r = 0.556, p = 0.013) and waist-to-hip ratio (r = 0.504, p = 0.012) in SAT samples.ConclusionCAD is associated with ABCA1 and ABCG1 DNA hypermethylation in EAT. CAD with concomitant carotid artery disease or peripheral artery disease is accompanied by decreased ABCA1 gene expression in EAT. DNA methylation levels at the ABCG1 cg27243685 locus in SAT are associated with hypertriglyceridemia and obesity.

Regulation of the expression of cholesterol transporters by lipid-lowering drugs ezetimibe and pemafibrate in rat liver and intestine

Ezetimibe and pemafibrate are lipid-lowering drugs and promote reverse cholesterol transport. However, it is unknown whether cholesterol is mainly excreted by hepatobiliary excretion or by non-biliary transintestinal cholesterol efflux (TICE). We evaluated the effects of ezetimibe and pemafibrate on hepatic and intestinal cholesterol transporter regulation in Sham-operated rats, and examined the effects of these drugs on TICE in bile duct-ligated rats. Seven-week-old male Sprague-Dawley rats were treated as follows for two weeks: 1) Sham, Sham operation; 2) BDL, bile duct ligation; 3) E-Sham, Sham + ezetimibe; 4) E-BDL, BDL + ezetimibe; 5) P-Sham, Sham + pemafibrate; and 6) P-BDL, BDL + pemafibrate. Blood, liver, jejunum, and feces were collected 72 h post-surgery. Hepatic cholesterol levels were decreased in P-Sham and E-Sham, and were lower in E-BDL and P-BDL than in BDL. Fecal cholesterol levels increased in E-Sham and P-Sham compared with Sham, and were higher in E-BDL and P-BDL than in BDL. In liver, Abcg5 mRNA showed induction in E-Sham, Abcg5 and Abca1 mRNA were induced in P-Sham, Abcg5 mRNA was reduced in E-BDL, and Abca1 mRNA was increased in P-BDL. In jejunum, Abcg5 mRNA was induced in E-Sham. Abcg8 mRNA was induced in E-Sham and P-Sham. NPC1L1 mRNA showed reduced expression in P-Sham and P-BDL. SR-B1 mRNA was reduced in P-Sham, and the expression decreased in P-BDL. LDL receptor mRNA was induced in BDL and P-BDL. Ezetimibe and pemafibrate may promote TICE by increasing Abcg5/g8, while pemafibrate may inhibit intestinal cholesterol absorption by decreasing SR-B1 and NPC1L1.

A calorie-restricted diet with nuts favourably raises plasma high-density lipoprotein-cholesterol in overweight and obese patients with stable coronary heart disease: A randomised controlled trial.

Weight loss and consumption of nuts may both improve plasma lipids and lipoproteins. However, their effects in patients with coronary artery disease (CAD) who are under treatment with statins remain unclear. This study was conducted to determine plasma lipid and lipoprotein responses to a low-calorie (25% of energy deficit) nuts containing diet (NELCD) compared with a nut-free energy-restricted diet (NFLCD) in stable CAD patients who were overweight or obese (n=67). Plasma lipids and lipoproteins and ATP-binding cassette (ABC) A1 and ABCG1 mRNA expressions in peripheral blood mononuclear cells (PBMCs) isolated from patients were assessed at baseline and after 8weeks. Plasma high-density lipoprotein (HDL) cholesterol and apoA1 increased significantly in the NELCD group at the end of Week 8 compared with those in NFLCD group (in NELCD group, mean change and 95% confidence interval (CI) were 1.17 [-1.31, 3.66] mg/dL, P=0.012, and 2.55 [-2.10, 7.20] mg/dL, P=0.011, for HDL cholesterol and apoA1, respectively). In both groups, the concentrations of total cholesterol, low-density lipoprotein cholesterol and triglyceride reduced significantly at Week 8 compared with those in baseline with no significant difference between the two groups. ABCA1 and ABCG1 mRNA expressions non-significantly decreased in both groups. This study indicates that inclusion of nuts as part of a calorie-restricted diet improves the concentrations of HDL cholesterol and apoA-1 in patients with stable, established CHD receiving statins.

The Expression of Genes Encoding ABCA1 and ABCG1 Transporters and PPARγ, LXRβ, and RORα Transcriptional Factors in Subcutaneous and Visceral Adipose Tissue in Women with Metabolic Syndrome

The study aimed to investigate tissue-specific gene expression of ABCA1 and ABCG1, encoding cholesterol transporters, as well as PPARG, LXRβ (NR1H2), and RORA, encoding the most important transcriptional regulators of lipid metabolism, in subcutaneous and visceral adipose tissue (SAT and VAT) in women with metabolic syndrome. It was shown that the ABCG1 mRNA SAT/VAT ratio decreases with age and correlates with the development of metabolic syndrome. After age adjustment, women have reduced chances of metabolic syndrome development when ABCG1 gene expression in SAT is higher relative to VAT than women with VAT ABCG1 gene expression higher or comparable to SAT: OR = 0.15 (95% CI 0.03-0.76), p = 0.023. The ABCA1 mRNA SAT/VAT ratio positively correlated with HDL cholesterol levels (after age adjustment β = 0.350, p = 0.046), therefore individuals with higher ABCA1 mRNA level in SAT relative to VAT had elevated HDL levels. The ABCA1 mRNA level in SAT was decreased in smokers (p = 0.001). There was a negative correlation between the PPARG mRNA level in SAT with body mass index and waist circumference in the general sample (β = -0.602, p = 0.003 and β = -0.642, p = 0.001, respectively, after age adjustment). A decrease of the PPARG mRNA SAT/VAT ratio was associated with elevated plasma insulin level and the insulin resistance index HOMA-IR β = -0.819, p = 0.004 and β = -1.053, p = 0.008, respectively, after age adjustment). Thus, the study has shown that the ratio of ABCA1, ABCG1, and PPARG genes expression in different types of adipose tissue (SAT/VAT) could be a significant factor that predicts the development of atherogenic dyslipidemia, metabolic syndrome, and insulin resistance in obesity.

FXR activation promotes intestinal cholesterol excretion and attenuates hyperlipidemia in SR-B1-deficient mice fed a high-fat and high-cholesterol diet.

Obeticholic acid (OCA) activates the farnesoid X receptor (FXR) to lower circulating total cholesterol (TC) and high density lipoprotein‐cholesterol (HDL‐C) concentrations and to stimulate fecal cholesterol excretion in mice by increasing hepatic SR‐B1 expression. Here we show that hepatic SR‐B1 depletion by an adenovirus expressing Sr‐b1 shRNA (Ad‐shSR‐B1) attenuated these beneficial effects of OCA in mice on a chow diet. The mRNA levels of ABC cholesterol transporter genes (Abca1, Abcg1, Abcg5, and Abcg8) were unchanged in the liver of hepatic SR‐B1‐depleted mice regardless of OCA treatment; however, a modest increase in Abca1, Abcg5, and Abcg8 mRNA levels was observed in the ileum of vehicle‐treated control mice and Abca1 and Abcg8 mRNA levels were increased more by OCA administration. OCA treatment of Sr‐b1 knock out (KO) mice (Sr‐b1‐/‐) fed a normal chow diet (NCD) displayed a similar lack of transhepatic cholesterol movement, as well as a modest increase in the levels of ileum cholesterol transporter expression. However, OCA treatment of Sr‐b1 KO mice fed a cholesterol‐enriched diet reduced circulating cholesterol and increased fecal cholesterol output to comparable degrees to that of wild‐type (WT) mice, and these effects were accompanied by substantial elevations of mRNA levels of Abca1, Abcg1, Abcg5, and Abcg8 in the ileum of Sr‐b1 KO mice. Our studies suggest that FXR activation stimulates intestinal cholesterol excretion and reduces diet‐induced hyperlipidemia through increased expression of ileal cholesterol transporters when hepatic SR‐B1‐mediated cholesterol movement is absent.

Brothers in Arms: ABCA1- and ABCG1-Mediated Cholesterol Efflux as Promising Targets in Cardiovascular Disease Treatment.

Atherosclerosis is a leading cause of cardiovascular disease worldwide, and hypercholesterolemia is a major risk factor. Preventive treatments mainly focus on the effective reduction of low-density lipoprotein cholesterol, but their therapeutic value is limited by the inability to completely normalize atherosclerotic risk, probably due to the disease complexity and multifactorial pathogenesis. Consequently, high-density lipoprotein cholesterol gained much interest, as it appeared to be cardioprotective due to its major role in reverse cholesterol transport (RCT). RCT facilitates removal of cholesterol from peripheral tissues, including atherosclerotic plaques, and its subsequent hepatic clearance into bile. Therefore, RCT is expected to limit plaque formation and progression. Cellular cholesterol efflux is initiated and propagated by the ATP-binding cassette (ABC) transporters ABCA1 and ABCG1. Their expression and function are expected to be rate-limiting for cholesterol efflux, which makes them interesting targets to stimulate RCT and lower atherosclerotic risk. This systematic review discusses the molecular mechanisms relevant for RCT and ABCA1 and ABCG1 function, followed by a critical overview of potential pharmacological strategies with small molecules to enhance cellular cholesterol efflux and RCT. These strategies include regulation of ABCA1 and ABCG1 expression, degradation, and mRNA stability. Various small molecules have been demonstrated to increase RCT, but the underlying mechanisms are often not completely understood and are rather unspecific, potentially causing adverse effects. Better understanding of these mechanisms could enable the development of safer drugs to increase RCT and provide more insight into its relation with atherosclerotic risk. SIGNIFICANCE STATEMENT: Hypercholesterolemia is an important risk factor of atherosclerosis, which is a leading pathological mechanism underlying cardiovascular disease. Cholesterol is removed from atherosclerotic plaques and subsequently cleared by the liver into bile. This transport is mediated by high-density lipoprotein particles, to which cholesterol is transferred via ATP-binding cassette transporters ABCA1 and ABCG1. Small-molecule pharmacological strategies stimulating these transporters may provide promising options for cardiovascular disease treatment.