Expression Of Cholesterol Metabolism Genes Research Articles

Betaine supplementation alleviates corticosterone-induced hepatic cholesterol accumulation through epigenetic modulation of HMGCR and CYP7A1 genes in laying hens

Excessive corticosterone (CORT) exposure could cause hepatic cholesterol accumulation in chickens and maternal betaine supplementation could decrease hepatic cholesterol deposition through epigenetic modifications in offspring chickens. Nevertheless, it remains uncertain whether providing betaine to laying hens could protect CORT-induced hepatic cholesterol accumulation via epigenetic mechanisms. This study aimed to examine the effects of dietary betaine on plasma and hepatic cholesterol contents, expression of cholesterol metabolic genes, as well as DNA methylation on their promoters in the liver of laying hens exposed to CORT. A total of 72 laying hens at 130 d of age were randomly divided into 3 groups: control (CON), CORT, and CORT+betaine (CORT+BET) groups. The experiment lasted for 35 d. Chickens in CON and CORT groups were fed a basal diet, whereas the CORT+BET group chickens were fed the basal diet supplemented with 0.1% betaine for 35 d. On d 28 of the experiment, chickens in CORT and CORT+BET groups received daily subcutaneous injections of CORT (4.0 mg/kg body weight), whereas the CON group chickens were injected with an equal volume of solvent for 7 d. The results showed that CORT administration led to a significant increase (P < 0.05) in the contents of cholesterol in plasma and liver, associated with activation (P < 0.05) of sterol regulatory element binding transcription factor 2 (SREBP2), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), lecithin-cholesterol acyltransferase (LCAT) and low-density lipoprotein receptor (LDLR) genes expression, and inhibition of cholesterol-7-alpha hydroxylase (CYP7A1) and sterol 27-hydroxylase (CYP27A1) genes expression in the liver compared to the CON. In contrast, CORT-induced up-regulation of HMGCR mRNA and protein abundances and downregulation of CYP7A1 mRNA and protein abundances were completely normalized (P < 0.05) by betaine supplementation. Besides, CORT injection led to significant hypomethylation (P < 0.05) on HMGCR promoter and hypermethylation (P < 0.05) on CYP7A1 promoter. Moreover, dietary betaine rescued (P < 0.05) CORT-induced changes in methylation status of HMGCR and CYP7A1 genes promoters. These results indicate that dietary betaine addition protects laying hens from CORT-induced hepatic cholesterol accumulation via epigenetic modulation of HMGCR and CYP7A1 genes.

Multiplex immunohistochemistry defines two cholesterol metabolism patterns predicting immunotherapeutic outcomes in gastric cancer

BackgroundThe role of cholesterol metabolism in gastric cancer (GC) and its implications for tumor characteristics and immunotherapy response remain poorly understood. In this study, our aim was to investigate this role, identify associated metabolic subtypes, and assess their clinical implications in GC.MethodsWe conducted a comprehensive analysis of cholesterol metabolism genes (CMGs) using transcriptomic data from TCGA and GEO. Based on 23 representative CMGs, we classified GC into metabolic subtypes. We evaluated clinical features and immune cell infiltration between these subtypes. Additionally, we identified a CMG signature and assessed its clinical relevance in GC. We retrospectively enrolled thirty-five GC patients receiving chemotherapy plus a PD-1 inhibitor to assess the CMG signature using multiplex immunohistochemistry.ResultsOur analysis revealed two cholesterol metabolism subtypes in GC: Cholesterol Metabolism Type 1 (CMT1) and Cholesterol Metabolism Type 2 (CMT2). These subtypes exhibited distinct patterns: CMT1 indicated heightened cholesterol biosynthesis, while CMT2 showed abnormal cholesterol transport. CMT2 was associated with unfavorable clinical features, enriched malignant pathways, and a pro-tumor immune microenvironment. Furthermore, we developed a five-CMG prognostic signature (ABCA1, NR1H3, TSPO, NCEH1, and HMGCR) that effectively predicted the prognosis of patients with GC and their response to chemotherapy plus a PD-1 inhibitor. This signature was validated in a clinical cohort using multiplex immunohistochemistry.ConclusionOur results highlight the effectiveness of cholesterol metabolism patterns as biomarkers for predicting the prognosis and immunotherapy response in GC. The expression of cholesterol metabolism genes and the assessment of cholesterol metabolism patterns have the potential to predict the outcome of immunotherapy and guide treatment strategies.

Pre-Clinical Validation of Targeting Cholesterol Metabolism for Radiotherapy Sensitization in Head and Neck Cancer

This study examines the potential benefits of targeting cholesterol metabolism in combination with radiation therapy (RT) for treating Head and Neck Squamous Cell Carcinoma (HNSCC). Despite advancements in RT delivery, 60% of patients still experience a relapse within 2 years, highlighting the need for improved treatment strategies. Our hypothesis is that a specific, biological response to RT by a subset of tumor cells drives radio-resistance and recurrence, and that targeting cholesterol metabolism may be an effective way to improve RT efficacy. To identify radiation-induced biological responses, whole-genome RNA sequencing analysis was carried out on Cal27 (HPV-) and UMSCC47 (HPV+) cell lines after X-Ray (6MeV Linac) or proton (pencil beam scanning, center part of SOBP) radiations. Potential radio-resistance targets were identified by comparing RT-induced transcriptomic changes with publicly available GEO and TCGA transcriptomic data from human HNSCC samples. Cholesterol metabolism as a driver of HNSCC radio-resistance was validated in vitro by pharmacological and genetic approaches. Transcriptomic analysis revealed a significant increase in 11 genes related to sterol and cholesterol in both the Cal27 and UMSCC47 cell lines after radiation exposure (pathway functional enrichment analysis, p = 2.05e-05). High expression of these RT-induced cholesterol gene signatures correlated with decreased overall survival among HNSCC patients based on the TCGA database (log rank p = 0.022, HR = 1.4). Moreover, a Gene Set Enrichment Analysis of the GSE23036 dataset (pre-treatment HNSCC tumors: locoregional recurrence vs. nonrecurrence) also linked cholesterol metabolism and local recurrence (p = 0.002, FDR = 0.07, NES = 1.72). Single-cell RNA sequencing data from the GSE164690 dataset revealed high expression of cholesterol metabolism genes in human HNSCC epithelial and mesenchymal fractions. In vitro studies demonstrated that RT increased the nuclear translocation of the master transcription factors controlling cholesterol gene expression SREBP2 and increased the expression of the SREBP2 target gene SQLE at the protein level. In accordance with this result, RT increased cellular cholesterol content and uptake in human (p = 0.027) and murine (p = 0.015) HNSCC cell lines. Drug or genetic targeting of SREBP2 reduced cellular cholesterol levels in HNSCC cells and increased toxicity when combined with RT in both 2D and 3D cell cultures compared to RT alone. Targeting cholesterol metabolism in combination with RT could be beneficial for treating HNSCC. In vivo validation in immunocompetent mouse models and orthotopic patient-derived xenograft models is ongoing.

Extracellular vesicles secreted by adipose tissue during obesity and type 2 diabetes mellitus influence cholesterol metabolism gene expression in human macrophages

Extracellular vesicles secreted by adipose tissue during obesity and type 2 diabetes mellitus influence cholesterol metabolism gene expression in human macrophages

Pleurotus Ostreatus Polyphenols Extract Based Diets Enhanced Hepatic Cholesterol Metabolism Related Gene Expression in Weaned Rabbits

Mycelium of oyster mushroom (Pleurotus ostreatus) contain active flavonoids that have antioxidant and suppressive cholesterolemic effects. This study was conducted to explore the mechanism and effects of dietary Pleurotus ostreatus phenolic supplementation on levels of cellular cholesterol deposition and metabolism in weaned rabbits. Twenty four (24) weaned rabbits were randomly divided into three groups with eight (8) replicates per group in a complete randomized design experiment. Rabbits were fed control diet (basal) and/or a control diet supplemented with 450 mg/kg or 900 mg/kg P. ostreatus phenolic extracts (POPE) for seven weeks. Blood and liver samples were collected to determine serum adiponectin and hepatic cholesterolic related genes. 3-hydroxyl-3 methyl-glutaryl coenzyme A reductase (HMG-CoAR) and cholesterol 7 α-hydroxylase (CTP7A1) mRNA levels and sterol regulatory element binding transcription factor 1(SREBF1) were down regulated while, Low-density lipoprotein receptor (LDL-R) and sterol co enzyme A desaturase gene (SCD) were up regulated to decrease fat mass, serum triglycerides (TG), serum total cholesterol and low density lipoprotein cholesterol (LDL-C) levels in rabbits on 450 and 900mg/kg P. ostreatus phenolic extract supplementation diets. Serum adiponectin concentration and High density lipoprotein cholesterol (HDL-C) increased from 22.5 to 32.09 and 1.21 to 1.56 mmol/L, respectively for control and POPE based diets. The results suggested that dietary supplementation of P. ostreatus extract at 900 mg/ kg diets could improve lipid metabolism in rabbits by regulating hepatic cholesterol metabolism gene expression and optimizing fatty acid uptake and synthesis.

Retinoic Acid Grafted to Hyaluronic Acid Activates Retinoid Gene Expression and Removes Cholesterol from Cellular Membranes.

All-trans-retinoic acid (atRA) is a potent ligand that regulates gene expression and is used to treat several skin disorders. Hyaluronic acid (HA) was previously conjugated with atRA (HA-atRA) to obtain a novel amphiphilic compound. HA-atRA forms micelles that incorporate hydrophobic molecules and facilitate their transport through the skin. The aim of this study was to determine the influence of HA-atRA on gene expression in skin cells and to compare it with that of unbound atRA. Gene expression was investigated using microarrays and a luciferase system with a canonical atRA promoter. HA-atRA upregulated gene expression similarly to atRA. However, HA-atRA activated the expression of cholesterol metabolism genes, unlike atRA. Further investigation using HPLC and filipin III staining suggested that the treated cells induced cholesterol synthesis to replenish the cholesterol removed from the cells by HA-atRA. HA modified with oleate (HA-C18:1) removed cholesterol from the cells similarly to HA-atRA, suggesting that the cholesterol removal stemmed from the amphiphilic nature of the two derivatives. HA-atRA induces retinoid signaling. Thus, HA-atRA could be used to treat skin diseases, such as acne and psoriasis, where the combined action of atRA signaling and anti-inflammatory cholesterol removal may be potentially beneficial.

Abstract 162: Cholesterol metabolism gene expression and prostate cancer-specific outcomes in radiotherapy-treated patients

Abstract Introduction Dysregulated lipid metabolism is a hallmark of prostate cancer. Furthermore, use of the cholesterol lowering statin drugs has been linked to a reduced risk of lethal prostate cancer. To understand the molecular pathways implicated in this relationship, we examined the association between differential expression of genes involved in intratumoral cholesterol metabolism in prostate tumor biopsies and prostate cancer-specific outcomes. Methods Tumor biopsy gene expression data from 242 men diagnosed with localized/locally advanced prostate cancer and treated with radiotherapy and androgen deprivation therapy was analyzed. A total of 71 genes involved in cholesterol transport, biosynthesis and regulation were selected from the Reactome pathway database, with additional genes involved in cholesterol metabolism extracted from literature. For each gene, expression levels were dichotomized by median expression level. Cox proportional hazards regression was used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for associations of gene expression with biochemical recurrence and metastasis. Models were adjusted for age at diagnosis and Gleason score. Multiple-testing correction was performed using the Bonferroni correction method. Results During a median follow-up of 10.4 years, 72 (30%) patients experienced biochemical recurrence and 32 (13%) developed metastatic disease. Differential expression of several genes was found to be associated with risk of biochemical recurrence and metastasis, though none remained statistically significant following Bonferroni correction. However, several genes showed similar patterns of association with risk of biochemical recurrence and of metastasis, an association which remained similar following adjustment for age and Gleason score. Low (below median) expression of FDFT1, a gene encoding squalene synthase, a key enzyme in cholesterol biosynthesis, was associated with an increased risk of biochemical recurrence (HR 1.87; 95% CI, 1.15-3.01) and metastasis (HR 3.52; 95% CI, 1.52-8.16). High (above median) expression of SLCO1B3, a gene encoding an organic anion transporting polypeptide transporting a variety of small molecules including statins, was associated with higher risk of biochemical recurrence (HR 2.14; 95% CI, 1.31-3.49) and metastasis (HR 2.70; 95% CI, 1.25-5.90). Conclusion These hypothesis-generating results point to a potential role for altered intratumoral cholesterol metabolism in prostate cancer-specific outcomes. Our findings highlighting differential expression of FDFT1 and SLCO1B3, genes involved in cholesterol biosynthesis and anion transport, respectively, in association with risk of biochemical recurrence and metastasis may provide clues as to the mechanistic pathways of most importance. Validation in other prostate cancer gene expression datasets is required. Citation Format: Sarah J. Winter, Sophia Halliday, Konrad H. Stopsack, Sarah O. Osman, Alan R. Hounsell, Gillian Prue, Suneil Jain, Emma H. Allott. Cholesterol metabolism gene expression and prostate cancer-specific outcomes in radiotherapy-treated patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 162.

Antioxidants activity and cholesterol regulation effect of Caralluma flava N.E.Br extract in HepG2 cells

Herbal medicine has a long-standing history in many locations in Yemen and continue to provide useful and applicable tools for treating ailments. The objectives of the present study are to investigate antioxidant activity and cholesterol regulatory effect of Caralluma flava N.E.Br methanolic extract (CFM) through chemical and molecular approaches. CFM afforded the yield of 18 % (w/w) through methanolic extraction and contained considerable amount of phenolic and flavonoid compounds (9.22 ± 1.4 mg/g) and 3.35 ± 0.16 mg/g respectively). Antioxidant activity assays revealed that CFM are effective antioxidant with 76.8% DPPH scavenging activity bleaching inhibitory activity. Result from s-carotene–linoleic acid assay shows that CFM efficiently retarded the oxidation of linoleic acid in the reaction system compared to control. CFM regulate the expression of cholesterol metabolism genes in HepG2 cells in a dose-dependent manner. The low-density lipoprotein receptor (LDLR) mRNA level was significantly up-regulated by 1.3, 2.4 and 3.2 fold compared to control cells. The mRNA level of 3-Hydroxy-3-Methylglutaryl-CoA Reductase (HMGCOA) was significantly suppressed by 12, 30 and 50% in a dose dependent manner compared to the control cells treated with 20, 50 and 100 µg/ml of CFM respectively. Apolipoprotein A-1 (Apo A-1) gene was up-regulated by 1.7 and 2.2 fold and apolipoprotein B100 (Apo B100) gene was suppressed by 11% and 24% in HepG2 cells treated with 50 and 100 µg/ml of CFM respectively, compared to control cells. In conclusion, CFM is a potential cardioprotector through enhancement of cholesterol regulation and exertion of antioxidant activity.

JTP-109192, a novel G protein-coupled receptor 119 agonist, prevents atherosclerosis by improving hypercholesterolaemia in congenic spontaneously hyperlipidaemic mice.

G protein-coupled receptor 119 (GPR119) expression in pancreatic β-cells and intestinal L-cells is a potential therapeutic target for the treatment of type 2 diabetes. Previously, we have reported that the GPR119 agonist JTP-109192 improves glucose metabolism with single and repeated administration. Conversely, overexpression of the Gpr119 gene reportedly regulates cholesterol transporter expression in animal models, and a natural GPR119 agonist, oleoylethanolamide (OEA), improves atherosclerosis. Therefore, improving dyslipidaemia is considered a possible feature of GPR119 agonists. In the present study, the lipid-lowering effect of JTP-109192 was examined in BALB/c background spontaneously hyperlipidaemic (SHL) mice with repeated administration, once daily for 12weeks. On repeated administration, JTP-109192 revealed a cholesterol-lowering effect and improved atherosclerosis following histopathological examination. With further investigation, the cholesterol-lowering effect and subsequent antiatherosclerotic effect of JTP-109192 was attributed to changes in intestinal cholesterol metabolism gene expression. Based on these results, JTP-109192 represents a new potential antihypercholesterolaemic agent for the treatment of dyslipidaemia.

Fetal betaine exposure modulates hypothalamic expression of cholesterol metabolic genes in offspring cockerels with modification of promoter DNA methylation

In documents, maternal betaine modulates hypothalamic cholesterol metabolism in chicken posthatchings, but it remains unclear whether this effect can be passed on by generations. In present study, eggs were injected with saline or betaine at 2.5 mg/egg, and the hatchlings (F1) were raised under the same condition until sexual maturation. Both the control group and the betaine group used artificial insemination to collect sperm from their cockerels. Fertilized eggs were incubated, and the hatchlings of the following generation (F2) were raised up to 64 D of age. F2 cockerels in betaine group showed significantly (P < 0.05) lower body weight, which was associated with significantly decreased (P < 0.05) hypothalamic content of total cholesterol and cholesterol ester. Concordantly, hypothalamic expression of cholesterol biosynthetic genes, SREBP2 and HMGCR, were significantly downregulated (P < 0.05), together with cholesterol conversion-related and excretion-related genes, CYP46A1 and ABCA1. These changes coincided with a significant downregulation in mRNA expression of regulatory neuropeptides including brain-derived neurotrophic factor, neuropeptide Y, and corticotropin-releasing hormone. Moreover, genes involved in methyl transfer cycle were also modified. Betaine homocysteine methyltransferase (P < 0.05) was downregulated, yet DNA methyltransferase1 tended to be upregulated (P = 0.06). S-adenosyl methionine/S-adenosylhomocysteine ratio was higher in the hypothalamus of betaine-treated F2 cockerels, which was associated with significantly modified CpG methylation on the promoter of those affected genes. These results suggested that betaine might regulate central cholesterol metabolism and hypothalamic expression of genes related to brain function by altering promoter DNA methylation in F2 cockerels.

Lipid and cholesterol metabolism gene expression in pterygium fibroblasts: comparative analysis with adipocytes and other fibroblasts

Lipid and cholesterol metabolism gene expression in pterygium fibroblasts: comparative analysis with adipocytes and other fibroblasts

The cholesterol biosynthesis pathway regulates IL-10 expression in human Th1 cells

The mechanisms controlling CD4+ T cell switching from an effector to an anti-inflammatory (IL-10+) phenotype play an important role in the persistence of chronic inflammatory diseases. Here, we identify the cholesterol biosynthesis pathway as a key regulator of this process. Pathway analysis of cultured cytokine-producing human T cells reveals a significant association between IL-10 and cholesterol metabolism gene expression. Inhibition of the cholesterol biosynthesis pathway with atorvastatin or 25-hydroxycholesterol during switching from IFNγ+ to IL-10+ shows a specific block in immune resolution, defined as a significant decrease in IL-10 expression. Mechanistically, the master transcriptional regulator of IL10 in T cells, c-Maf, is significantly decreased by physiological levels of 25-hydroxycholesterol. Strikingly, progression to rheumatoid arthritis is associated with altered expression of cholesterol biosynthesis genes in synovial biopsies of predisposed individuals. Our data reveal a link between sterol metabolism and the regulation of the anti-inflammatory response in human CD4+ T cells.

Dietary betaine supplementation in hens modulates hypothalamic expression of cholesterol metabolic genes in F1 cockerels through modification of DNA methylation.

Betaine is widely used in animal nutrition to promote growth, development and methyl donor during methionine metabolism through nutritional reprogramming via regulation of gene expression. Prenatal betaine exposure is reported to modulate hypothalamic cholesterol metabolism in chickens, yet it remains unknown whether feeding hens with betaine-supplemented diet may affect hypothalamic cholesterol metabolism in F1 offspring. In this study, hens were fed with basal or betaine-supplemented (0.5%) for 30days, and the eggs were collected for incubation. The hatchlings were raised under the same condition up to 56days of age. Betaine-treated group showed significantly (P<0.05) higher plasma concentration of total cholesterol and HDL-cholesterol, together with increased hypothalamic content of total cholesterol and cholesterol ester. Concordantly, hypothalamic gene expression of SREBP2, HMGCR, and LDLR was significantly up regulated (P<0.05). Also, mRNA abundances of SREBP1, ACAT1 and APO-A1 were up-regulated, while that of CYP46A1 was significantly down-regulated (P<0.05). These changes coincided with a significant down-regulation of BDNF and CRH, and a significant up-regulation of NPY mRNA expression. Moreover, genes involved in methyl transfer cycle were also modulated. DNMT1 and BHMT were up-regulated (P<0.05) at both mRNA and protein levels, which was associated with significant modifications of CpG methylation on the promoter of SREBP-1, SREBP-2 and APO-A1 genes as detected by bisulfate sequencing. These results indicate that feeding betaine to hens modulates hypothalamic expression of genes involved in cholesterol metabolism and brain functions in F1 cockerels with modification of promoter DNA methylation.

Prenatal betaine exposure modulates hypothalamic expression of cholesterol metabolic genes in cockerels through modifications of DNA methylation

Cholesterol is essential for neuronal development and brain function. Previously we reported that in ovo administration of betaine modulates hepatic cholesterol metabolism in the chicken, yet it remains unknown whether maternal betaine affects the cholesterol content and the expression of cholesterol metabolic genes in chicken hypothalamus. In this study, eggs were injected with saline or betaine at 2.5 mg/egg, and the hatchlings were raised under the same condition until 64 d of age. Maternal betaine significantly (P = 0.05) increased the body weight and suppressed aggressive behavior of 64-day-old cockerels, in association with significantly (P < 0.05) up-regulated expression of 5-HTR1A receptor in the hypothalamus. Concurrently, betaine in ovo significantly increased (P < 0.05) the hypothalamic content of total cholesterol and cholesterol ester, which coincided with significantly up-regulated (P < 0.05) hypothalamic expression of cholesterol biosynthetic genes, such as sterol-regulatory element binding protein 2 and 3-hydroxy-3-methyl-glutaryl-CoA reductase as well as acetyl-CoA cholesterol acyltransferase 1, which converts free cholesterol to cholesterol ester for storage. In contrast, low density lipoprotein receptor, which mediates the cholesterol uptake, was significantly down-regulated (P < 0.05). In ovo betaine administration significantly enhanced the expression of betaine-homocysteine methyltransferase and DNA methyltransferase 1 (P < 0.05), which was associated with alterations of CpG methylation on the promoter of modified cholesterol metabolic genes. These results indicate that maternal betaine modulates hypothalamic cholesterol metabolism in cockerels through modifying DNA methylation on the promoter of cholesterol metabolic genes.

Vascular Disease Is Associated With the Expression of Genes for Intestinal Cholesterol Transport and Metabolism.

Intestinal cholesterol metabolism is important in influencing postprandial lipoprotein concentrations, and might be important in the development of vascular disease. This study evaluated associations between expression of intestinal cholesterol metabolism genes, postprandial lipid metabolism, and endothelial function/early vascular disease in human subjects. One hundred patients undergoing routine oesophago-gastro-duodenoscopy were recruited. mRNA levels of Nieman-Pick C1-like 1 protein (NPC1L1), ABC-G5, ABC-G8, ABC-A1, microsomal tissue transport protein (MTTP), and sterol-regulatory element-binding protein (SREBP)-2 were measured in duodenal biopsies using quantitative reverse transcription polymerase chain reaction. Postprandially, serum lipid and glycemic profiles were measured, endothelial function was assessed using fasting, and postprandial flow-mediated dilatation (FMD) and carotid intima-media thickness (IMT). Subjects were divided into those above and below the median value of relative expression of each gene, and results were compared between the groups. There were no between-group differences in demographic variables or classical cardiovascular risks. For all genes, the postprandial triglyceride incremental area under the curve was greater (P < 0.05) in the group with greater expression. Postprandial apolipoprotein B48 (ApoB48) levels were greater (P < 0.05) in groups with greater expression of NPC1L1, ABC-G8, and SREBP-2. For all genes, postprandial but not fasting FMD was lower (P < 0.01) in the group with greater expression. Triglyceride and ApoB48 levels correlated significantly with postprandial FMD. Carotid artery IMT was greater (P < 0.05) in groups with greater expression of MTTP, ABC-A1, and SREBP-2. Intestinal cholesterol metabolism gene expression is significantly associated with postprandial increment in triglycerides, intestinal ApoB48, and reduced postprandial FMD. Some genes were also associated with increased IMT. These findings suggest a role of intestinal cholesterol metabolism in development of early vascular disease.

Monocytes from HIV-infected individuals show impaired cholesterol efflux and increased foam cell formation after transendothelial migration.

HIV-infected (HIV+) individuals have an increased risk of atherosclerosis and cardiovascular disease which is independent of antiretroviral therapy and traditional risk factors. Monocytes play a central role in the development of atherosclerosis, and HIV-related chronic inflammation and monocyte activation may contribute to increased atherosclerosis, but the mechanisms are unknown. Using an in-vitro model of atherosclerotic plaque formation, we measured the transendothelial migration of purified monocytes from age-matched HIV+ and uninfected donors and examined their differentiation into foam cells. Cholesterol efflux and the expression of cholesterol metabolism genes were also assessed. Monocytes from HIV+ individuals showed increased foam cell formation compared with controls (18.9 vs. 0%, respectively, P = 0.004) and serum from virologically suppressed HIV+ individuals potentiated foam cell formation by monocytes from both uninfected and HIV+ donors. Plasma tumour necrosis factor (TNF) levels were increased in HIV+ vs. control donors (5.9 vs. 3.5 pg/ml, P = 0.02) and foam cell formation was inhibited by blocking antibodies to TNF receptors, suggesting a direct effect on monocyte differentiation to foam cells. Monocytes from virologically suppressed HIV+ donors showed impaired cholesterol efflux and decreased expression of key genes regulating cholesterol metabolism, including the cholesterol transporter ABCA1 (P = 0.02). Monocytes from HIV+ individuals show impaired cholesterol efflux and are primed for foam cell formation following transendothelial migration. Factors present in HIV+ serum, including elevated TNF levels, further enhance foam cell formation. The proatherogenic phenotype of monocytes persists in virologically suppressed HIV+ individuals and may contribute mechanistically to increased atherosclerosis in this population.

Maternal dietary betaine supplementation modifies hepatic expression of cholesterol metabolic genes via epigenetic mechanisms in newborn piglets.

To elucidate the effects of maternal dietary betaine supplementation on hepatic expression of cholesterol metabolic genes in newborn piglets and the involved epigenetic mechanisms, we fed gestational sows with control or betaine-supplemented diets (3g/kg) throughout pregnancy. Neonatal piglets born to betaine-supplemented sows had higher serum methionine concentration and hepatic content of betaine, which was associated with significantly up-regulated hepatic expression of glycine N-methyltransferase. Prenatal betaine exposure increased hepatic cholesterol content and modified the hepatic expression of cholesterol metabolic genes in neonatal piglets. Sterol regulatory element-binding protein 2 was down-regulated at both mRNA and protein levels, while 3-hydroxy-3-methylglutaryl CoA reductase (HMGCR) was down-regulated at the mRNA level, but up-regulated at the protein level, in betaine-exposed piglets. The transcriptional repression of HMGCR was associated with CpG island hypermethylation and higher repressive histone mark H3K27me3 (histone H3 lysine 27 trimethylation) on the promoter, whereas increased HMGCR protein content was associated with significantly decreased expression of miR-497. Furthermore, LDL receptor was significantly down-regulated at both mRNA and protein levels in the liver of betaine-exposed piglets, which was associated with promoter CpG hypermethylation. In addition, the expression of cholesterol-27α-hydroxylase (CYP27α1) was up-regulated at both mRNA and protein levels, while the expression of cholesterol-7α-hydroxylase (CYP7α1) was increased at the mRNA level, but unchanged at the protein level associated with increased expression of miR-181. These results indicate that maternal betaine supplementation increases hepatic cholesterol content in neonatal piglets through epigenetic regulations of cholesterol metabolic genes, which involve alterations in DNA and histone methylation and in the expression of microRNA targeting these genes.

Recipient perioperative cholesterolaemia and graft cholesterol metabolism gene expression predict liver transplant outcome

We analysed for the first time whether recipient perioperative serum total cholesterol (sTC) concentration is associated with liver transplantation outcome. We studied noncholestatic cirrhotics submitted to primary deceased-donor liver transplantation in a prospective group (n=140) from Rome and in a validation retrospective cohort (n=157) from Udine, Italy. Pre-ischaemia and post-reperfusion cholesterol metabolism gene mRNA was measured by RT-PCR in 74 grafts of the study group. At Cox regression analysis, independently from confounders including recipient MELD score, the recipient pre-operative sTC pooled quintiles 2-5, compared with the lowest quintile showed HR (95% CI) and significances for overall graft loss (GL) of 0.215 (0.104-0.444) P<0.001 in the study group and 0.319 (0.167-0.610) P=0.001 in the validation cohort. Analysing sTC as a continuous variable, the risk of overall GL for every 10-mg/dl decrease in pre-operative sTC increased by 13% and by 9% in the study group and in the validation cohort respectively. In the study group, independent associations at multivariate analyses were: (a) high graft pre-ischaemia expression of INSIG-1, which indicates hepatocellular cholesterol depletion, with post-reperfusion graft necrosis; (b) GL with inadequate graft post-reperfusion response to cholesterol depletion, shown by a failure to reduce the PCSK9 to LDLR expression ratio; (c) GL with a relative increase of sTC on post-operative day-7, selectively because of the LDL fraction, which indirectly suggests poor cholesterol uptake from blood. Low recipient pre-transplant sTC concentration, its post-operative day-7 increase and a genetically determined low graft cholesterol availability predict poor liver transplant outcome.

Diet supplementation with beta-carotene improves the serum lipid profile in rats fed a cholesterol-enriched diet

The present study investigated the underlying mechanism associated with the hypocholesterolemic activity of beta-carotene by examining its effects on the serum lipid profile, fecal cholesterol excretion, and gene expression of the major receptors, enzymes, and transporters involved in cholesterol metabolism. Female Fischer rats were divided into three groups and were fed either a control or a hypercholesterolemic diet supplemented or not supplemented with 0.2 % beta-carotene. After 6 weeks of feeding, blood, livers, and feces were collected for analysis, and quantitative real-time polymerase chain reaction (qRT-PCR) was performed. Dietary supplementation with 0.2 % beta-carotene decreased serum total cholesterol, non-HDL cholesterol, the atherogenic index, and hepatic total lipid and cholesterol contents. These changes were accompanied by an increase in the total lipid and cholesterol contents excreted in the feces. The qRT-PCR analyses demonstrated that the hypercholesterolemic diet promoted a decrease in the gene expression of sterol regulatory element-binding protein 2, 3-hydroxy-3-methylglutaryl CoA reductase, and low-density lipoprotein receptor and an increase in the gene expression of peroxisome proliferator-activated receptor α and cholesterol-7a-hydroxylase. The expression of these genes and gene expression of ATP-binding cassette subfamily G transporters 5and 8 were unaffected by beta-carotene supplementation. In conclusion, the decrease in serum cholesterol and the elevation of fecal cholesterol obtained following beta-carotene administration indicate that this substance may decrease cholesterol absorption in the intestine and increase cholesterol excretion into the feces without a direct effect on the expression of cholesterol metabolism genes.

The Expression of Cholesterol Metabolism Genes in Monocytes From HIV-Infected Subjects Suggests Intracellular Cholesterol Accumulation

Human immunodeficiency virus (HIV) infection is associated with increased cardiovascular risk and reduced high-density lipoprotein cholesterol (HDL-c). In vitro, HIV impairs monocyte-macrophage cholesterol efflux, a major determinant of circulating HDL-c, by increasing ABCA1 degradation, with compensatory upregulation of ABCA1 messenger RNA (mRNA). We examined expression of genes involved in cholesterol uptake, metabolism, and efflux in monocytes from 22 HIV-positive subjects on antiretroviral therapy (ART-Treated), 30 untreated HIV-positive subjects (ART-Naive), and 22 HIV-negative controls (HIV-Neg). HDL-c was lower and expression of ABCA1 mRNA was higher in ART-Naive subjects than in both ART-Treated and HIV-Neg subjects (both P < .01), with HDL-c inversely correlated with HIV RNA (ρ = -0.52; P < .01). Expression of genes involved in cholesterol uptake (LDLR, CD36), synthesis (HMGCR), and regulation (SREBP2, LXRA) was significantly lower in both ART-Treated and ART-Naive subjects than in HIV-Neg controls. In vivo, increased monocyte ABCA1 expression in untreated HIV-infected patients and normalization of ABCA1 expression with virological suppression by ART supports direct HIV-induced impairment of cholesterol efflux previously demonstrated in vitro. However, decreased expression of cholesterol sensing, uptake, and synthesis genes in both untreated and treated HIV infection suggests that both HIV and ART affect monocyte cholesterol metabolism in a pattern consistent with accumulation of intramonocyte cholesterol.