scholarly journals Sterol 27-hydroxylase gene dosage and the antiatherosclerotic effect of Rifampicin in mice

2018 ◽  
Vol 38 (1) ◽  
Author(s):  
Line Zurkinden ◽  
Dmitri Sviridov ◽  
Bruno Vogt ◽  
Geneviève Escher

Sterol 27-hydroxylase (CYP27A1) catalyzes the hydroxylation of cholesterol to 27-hydroxycholesterol (27-OHC) and regulates cholesterol homeostasis. In Cyp27a1/ Apolipoprotein E (ApoE) double knockout (KO) mice fed with Western diet (WD), the atherosclerotic phenotype found in ApoE KO mice was reversed. As protective mechanism, up-regulation of Cyp3a11 and Cyp7a1 was proposed. Cyp27a1 heterozygote/ApoE KO (het) mice, with reduced Cyp27a1 expression and normal levels of Cyp7a1 and Cyp3a11, developed more severe lesions than ApoE KO mice. To analyze the contribution of Cyp3a11 to the protection of atherosclerosis development, Cyp3a11 was induced by Rifampicin (RIF) in ApoE KO and het mice. Males were fed with WD and treated daily with RIF (10 mg/kg ip) or vehicle for 4 weeks. Atherosclerosis was quantified in the aortic valve. Plasma lipids and 27-hydroxycholesterol (27-OHC), expression of cytochromes P450 and genes involved in cholesterol transport and bile acids (BAs) signaling in liver and intestine, and intestinal cholesterol absorption were analyzed. RIF increased expression of hepatic but not intestinal Cyp3a11 4-fold in both genotypes. In ApoE KO mice treated with RIF, we found a 2-fold decrease in plasma cholesterol, and a 2-fold increase in high-density lipoprotein/low-density lipoprotein ratio and CY27A1 activity. Intestinal cholesterol absorption remained unchanged and atherosclerotic lesions decreased approximately 3-fold. In het mice, RIF had no effect on plasma lipids composition, CYP27A1 activity, and atherosclerotic plaque development, despite a reduction in cholesterol absorption. In conclusion, the antiatherogenic effect of Cyp3a11 induction by RIF was also dependent on Cyp27a1 expression.

2011 ◽  
Vol 301 (1) ◽  
pp. G148-G155 ◽  
Author(s):  
Pradeep Kumar ◽  
Pooja Malhotra ◽  
Ke Ma ◽  
Amika Singla ◽  
Omar Hedroug ◽  
...  

Curcumin, the major phenolic compound in the spice turmeric, exhibits numerous biological effects, including lowering plasma cholesterol and preventing diet-induced hypercholesterolemia. The mechanisms underlying the hypocholesterolemic effect of curcumin are not fully understood. In this regard, intestinal Niemann-Pick C1-like 1 (NPC1L1) cholesterol transporter, the molecular target of intestinal cholesterol absorption inhibitor ezetimibe, plays an essential role in the maintenance of cholesterol homeostasis. The current studies were designed to investigate the effect of curcumin on NPC1L1 function, expression, and promoter activity in intestinal Caco-2 monolayers. NPC1L1 function was evaluated by the measurement of ezetimibe-sensitive [3H]cholesterol esterification. Relative abundance of NPC1L1 mRNA and protein was evaluated by real-time PCR and Western blotting, respectively. Luciferase assays were used to measure NPC1L1 promoter activity. Our results showed that curcumin significantly inhibited ezetimibe-sensitive cholesterol esterification in a dose-dependent manner with a maximum decrease (by 52% compared with control) occurring at 50 μM concentration. Curcumin treatment of Caco-2 monolayers also significantly decreased NPC1L1 mRNA and protein expression. Similarly, the promoter activity of the NPC1L1 gene was inhibited significantly (55%) by 50 μM curcumin. The decrease in NPC1L1 promoter activity by curcumin was associated with a reduction in the expression and the DNA-binding activity of the sterol response element-binding protein 2 (SREBP2) transcription factor. Furthermore, the overexpression of active SREBP2 protected NPC1L1 from the inhibitory effect of curcumin. Our studies demonstrate that curcumin directly modulates intestinal NPC1L1 expression via transcriptional regulation and the involvement of SREBP2 transcription factor.


2020 ◽  
Vol 11 ◽  
Author(s):  
Wen-wen Huang ◽  
Bi-hong Hong ◽  
Kai-kai Bai ◽  
Ran Tan ◽  
Ting Yang ◽  
...  

Hypercholesterolemia is a preventable risk factor for atherosclerosis and cardiovascular disease. However, the mechanisms whereby cis-palmitoleic acid (cPOA) and trans-palmitoleic acid (tPOA) promote cholesterol homeostasis and ameliorate hypercholesterolemia remain elusive. To investigate the effects of cPOA and tPOA on cholesterol metabolism and its mechanisms, we induced hypercholesterolemia in mice using a high-fat diet and then intragastrically administered cPOA or tPOA once daily for 4 weeks. tPOA administration reduced serum cholesterol, low-density lipoprotein, high-density lipoprotein, and hepatic free cholesterol and total bile acids (TBAs). Conversely, cPOA had no effect on these parameters except for TBAs. Histological examination of the liver, however, revealed that cPOA ameliorated hepatic steatosis more effectively than tPOA. tPOA significantly reduced the expression of 3-hydroxy-3-methyl glutaryl coenzyme reductase (HMGCR), LXRα, and intestinal Niemann-Pick C1-Like 1 (NPC1L1) and increased cholesterol 7-alpha hydroxylase (CYP7A1) in the liver, whereas cPOA reduced the expression of HMGCR and CYP7A1 in the liver and had no effect on intestinal NPC1L1. In summary, our results suggest that cPOA and tPOA reduce cholesterol synthesis by decreasing HMGCR levels. Furthermore, tPOA, but not cPOA, inhibited intestinal cholesterol absorption by downregulating NPC1L1. Both high-dose tPOA and cPOA may promote the conversion of cholesterol into bile acids by upregulating CYP7A1. tPOA and cPOA prevent hypercholesterolemia via distinct mechanisms.


2008 ◽  
Vol 295 (5) ◽  
pp. G873-G885 ◽  
Author(s):  
Z. Ravid ◽  
M. Bendayan ◽  
E. Delvin ◽  
A. T. Sane ◽  
M. Elchebly ◽  
...  

Growing evidence suggests that the small intestine may contribute to excessive postprandial lipemia, which is highly prevalent in insulin-resistant/Type 2 diabetic individuals and substantially increases the risk of cardiovascular disease. The aim of the present study was to determine the role of high glucose levels on intestinal cholesterol absorption, cholesterol transporter expression, enzymes controlling cholesterol homeostasis, and the status of transcription factors. To this end, we employed highly differentiated and polarized cells (20 days of culture), plated on permeable polycarbonate filters. In the presence of [14C]cholesterol, glucose at 25 mM stimulated cholesterol uptake compared with Caco-2/15 cells supplemented with 5 mM glucose ( P < 0.04). Because combination of 5 mM glucose with 20 mM of the structurally related mannitol or sorbitol did not change cholesterol uptake, we conclude that extracellular glucose concentration is uniquely involved in the regulation of intestinal cholesterol transport. The high concentration of glucose enhanced the protein expression of the critical cholesterol transporter NPC1L1 and that of CD36 ( P < 0.02) and concomitantly decreased SR-BI protein mass ( P < 0.02). No significant changes were observed in the protein expression of ABCA1 and ABCG8, which act as efflux pumps favoring cholesterol export out of absorptive cells. At the same time, 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity was decreased ( P < 0.007), whereas ACAT activity remained unchanged. Finally, increases were noted in the transcription factors LXR-α, LXR-β, PPAR-β, and PPAR-γ along with a drop in the protein expression of SREBP-2. Collectively, our data indicate that glucose at high concentrations may regulate intestinal cholesterol transport and metabolism in Caco-2/15 cells, thus suggesting a potential influence on the cholesterol absorption process in Type 2 diabetes.


Nutrients ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1524 ◽  
Author(s):  
Bruce Griffin ◽  
Celia Walker ◽  
Susan Jebb ◽  
Carmel Moore ◽  
Gary Frost ◽  
...  

We examined the impact of APOE genotype on plasma lipids and glucose in a secondary analysis of data from a five-arm, randomised controlled, parallel dietary intervention trial (‘RISCK’ study), to investigate the impact of replacing saturated fatty acids (SFA) with either monounsaturated fat (MUFA) or carbohydrate of high or low glycaemic index (GI) on CVD risk factors and insulin sensitivity. We tested the impact of APOE genotype (carriage of E2 and E4 alleles versus E3/E3), determined retrospectively, on plasma lipids, lipoproteins and glucose homeostasis at baseline (n = 469), and on the change in these variables after 24 weeks of dietary intervention (n = 389). At baseline, carriers of E2 (n = 70), E4 (n = 125) and E3/E3 (n = 274) expressed marked differences in total plasma cholesterol (TC, p = 0.001), low density lipoprotein cholesterol (LDL-C, p < 0.0001), apolipoprotein B (apo B, p < 0.0001) and total to high density lipoprotein cholesterol ratio (TC:HDL-C, p = 0.002), with plasma concentrations decreasing in the order E4 > E3/E3 > E2. Following intervention, there was evidence of a significant diet x genotype interaction with significantly greater decreases in TC (p = 0.02) and apo B (p = 0.006) among carriers of E4 when SFA was replaced with low GI carbohydrate on a lower fat diet (TC −0.28 mmol/L p = 0.03; apo B −0.1 g/L p = 0.02), and a relative increase in TC (in comparison to E3/E3) when SFA was replaced with MUFA and high GI carbohydrates (TC 0.3 mmol/L, p = 0.03). Among carriers of E2 (compared with E3/E3) there was an increase in triacylglycerol (TAG) when SFA was replaced with MUFA and low GI carbohydrates 0.46 mmol/L p = 0.001). There were no significant interactions between APOE genotype and diet for changes in indices of glucose homeostasis. In conclusion, variations in APOE genotype led to differential effects on the lipid response to the replacement of SFA with MUFA and low GI carbohydrates.


2005 ◽  
Vol 94 (3) ◽  
pp. 331-337 ◽  
Author(s):  
Ariëtte M. van Bennekum ◽  
David V. Nguyen ◽  
Georg Schulthess ◽  
Helmut Hauser ◽  
Michael C. Phillips

Fibres with a range of abilities to perturb cholesterol homeostasis were used to investigate how the serum cholesterol-lowering effects of insoluble dietary fibres are related to parameters of intestinal cholesterol absorption and hepatic cholesterol homeostasis in mice. Cholestyramine, chitosan and cellulose were used as examples of fibres with high, intermediate and low bile acid-binding capacities, respectively. The serum cholesterol levels in a control group of mice fed a high fat/high cholesterol (HFHC) diet for 3 weeks increased about 2-fold to 4·3 mm and inclusion of any of these fibres at 7·5 % of the diet prevented this increase from occurring. In addition, the amount of cholesterol accumulated in hepatic stores due to the HFHC diet was reduced by treatment with these fibres. The three kinds of fibres showed similar hypocholesterolaemic activity; however, cholesterol depletion of liver tissue was greatest with cholestyramine. The mechanisms underlying the cholesterol-lowering effect of cholestyramine were (1) decreased cholesterol (food) intake, (2) decreased cholesterol absorption efficiency, and (3) increased faecal bile acid and cholesterol excretion. The latter effects can be attributed to the high bile acid-binding capacity of cholestyramine. In contrast, incorporation of chitosan or cellulose in the diet reduced cholesterol (food) intake, but did not affect either intestinal cholesterol absorption or faecal sterol output. The present study provides strong evidence that above all satiation and satiety effects underlie the cholesterol-lowering properties of insoluble dietary fibres with moderate or low bile acid-binding capabilities.


2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Jahangir Iqbal ◽  
Mohamed Boutjdir ◽  
Lawrence L Rudel ◽  
M Mahmood Hussain

Intestinal cholesterol absorption involves chylomicron and high density lipoprotein (HDL) pathways. Microsomal triglyceride transfer protein (MTP) and ATP binding cassette family A protein 1 (ABCA1) are critical for cholesterol transport by these pathways, respectively. Additionally, acyl Co-A:cholesterol acyltransferase 2 (ACAT2) plays an important role in cholesterol absorption. Intestinal MTP ablation significantly increased intestinal triglyceride and cholesterol levels and reduced their acute absorption. In contrast, ACAT2 deficiency had no effect on triglyceride absorption but significantly reduced cholesterol absorption. Individual deficiencies of ACAT2 and MTP reduced cholesterol absorption with chylomicrons. We hypothesized that their combined deficiency would increase cholesterol secretion with HDL; unexpectedly, their deficiency reduced secretion with both chylomicrons and HDL. Further, we observed significant reductions in intestinal ABCA1 expression in combined deficient mice. Thus, free cholesterol is unavailable for secretion by the HDL pathway in these mice. We speculate that reductions in ABCA1 expression and HDL secretion might be secondary to massive triglyceride accumulation associated with intestinal MTP deficiency. Besides its role in cholesterol absorption, ACAT2 deficiency causes mild hypertriglyceridemia and reduces steatosis in mice fed high cholesterol diets by increasing hepatic lipoprotein production by unknown mechanisms. We show that this phenotype is preserved in the absence of intestinal MTP in ACAT2 deficient mice fed a Western diet. Further, we observed increases in hepatic MTP activity in these mice. Thus, ACAT2 deficiency might increase MTP expression to avoid steatosis. Therefore, ACAT2 inhibition might avert steatosis associated with high cholesterol diets by increasing MTP expression.


2017 ◽  
Vol 37 (suppl_1) ◽  
Author(s):  
Sara Irani ◽  
Jahangir Iqbal ◽  
M.Mahmood Hussain

High plasma cholesterol levels are found in several metabolic disorders and their reductions are advocated to reduce risk of atherosclerosis. A way to lower plasma lipids is to curtail lipoprotein assembly and secretion; however, this is associated with steatosis. We have shown that microRNA-30c (miR-30c) reduces Western diet-induced hypercholesterolemia and atherosclerosis in C57BL/6J and Apoe -/- mice with no obvious adverse effects by reducing hepatic lipoprotein production and lipid synthesis. Here, we tested the effect of miR-30c on plasma lipids, transaminases and hepatic lipids in five different mouse models. Hepatic delivery of miR-30c reduced MTP activity but did not affect plasma cholesterol, triglyceride and glucose in chow-fed C57Bl6J and streptozotocin-induced diabetic, normolipidemic mice. However, hepatic delivery of miR-30c to chow fed leptin deficient ( ob/ob ) and leptin receptor deficient ( db/db ) hypercholesterolemic and hyperglycemic type 2 diabetic mice reduced cholesterol in total plasma and VLDL/LDL by ~ 28%and ~ 25%, respectively, without affecting phospholipid, triglyceride and glucose levels. Interestingly, these mice had lower plasma transaminases and creatine kinases indicating possible beneficial effects. Mechanistic studies showed that miR-30c reduced hepatic MTP activity and lipid synthesis. Moreover, miR-30c significantly lowered plasma cholesterol and atherosclerosis in Western-diet fed low density lipoprotein receptor knockout mice with no effect on plasma triglyceride, glucose and transaminases, suggesting that miR-30c can be a potential therapeutic agent for homozygous familial hypercholesterolemia. In all these studies, hepatic lipid levels were similar in control and miR-30c injected mice. These studies indicate that miR-30c reduces plasma cholesterol in diet-induced and diabetic hyperholesterolemic mice but not in normocholesterolemic mice. Thus, miR-30c may be beneficial in lowering plasma cholesterol in different metabolic disorders independent of the origin of hypercholesterolemia.


Blood ◽  
1991 ◽  
Vol 77 (4) ◽  
pp. 750-755 ◽  
Author(s):  
JB Stoudemire ◽  
MB Garnick

Abstract Recombinant human macrophage colony-stimulating factor (rhM-CSF) is a hematopoietic growth factor that stimulates the growth, differentiation, proliferation, and activation of cells of the monocyte/macrophage lineage. rhM-CSF was administered to rabbits and nonhuman primates to evaluate effects on cholesterol homeostasis. Decreases in plasma cholesterol concentrations were observed during rhM- CSF administration. The observed mean (+/- SD) decreases over a range of doses in nonhuman primates receiving rhM-CSF by continuous intravenous infusion (CIVI) or intravenous bolus (IVB) injection were approximately 16% +/- 8% and 43% +/- 10%, respectively. Low-density lipoprotein (LDL) cholesterol levels decreased 55% +/- 9% from pretreatment baseline values in the animals receiving rhM-CSF by IVB. Normocholesterolemic New Zealand white rabbits receiving rhM-CSF over a range of doses by CIVI showed a decrease from baseline in total cholesterol of approximately 28% +/- 17%, with LDL cholesterol levels decreasing by approximately 72% +/- 33%, while high-density lipoprotein levels showed variable changes, including increased values. A decrease of 36% +/- 26% in total plasma cholesterol was observed in Watanabe Heritable Hyperlipidemic rabbits receiving rhM-CSF by CIVI for 7 days. This decrease was attributable almost entirely to decreases in LDL cholesterol, which fell approximately 34% +/- 24% from baseline. Although the mechanism of this cholesterol-lowering effect is unknown, these results strongly suggest that rhM-CSF may provide a novel treatment for hypercholesterolemia and may be useful in investigations into the mechanisms of cholesterol homeostasis and atherogenesis.


2019 ◽  
Vol 149 (6) ◽  
pp. 996-1003 ◽  
Author(s):  
An Tien Nguyen ◽  
Sami Althwab ◽  
Haowen Qiu ◽  
Richard Zbasnik ◽  
Carlos Urrea ◽  
...  

ABSTRACT Background Pinto beans contain multiple active agents such as polyphenols, flavonoids, and saponins, and have been shown to lower cholesterol, but the mechanisms involved in this effect have not been explored. Objective This study was to investigate the changes in cholesterol metabolism in response to whole pinto beans (wPB) and their hulls (hPB) supplemented into a diet rich in saturated fat and the molecular mechanisms potentially responsible for these effects in hamsters. Methods Forty-four 9-wk-old male Golden Syrian hamsters were randomly assigned to 4 diet groups (n = 11), including a 5% (wt:wt) fat diet [normal-fat diet (NF)], a 15% (wt:wt) fat diet [diet rich in saturated fat (HSF), saturated fatty acids accounted for 70% of total fatty acids], or HSF supplemented with 5% (wt:wt) wPB or 0.5% (wt:wt) hPB for 4 wk. Plasma, liver, intestinal, and fecal samples were collected to evaluate multiple cholesterol markers and gene targets. Results The plasma non-high-density lipoprotein (non-HDL) concentration was significantly reduced in the wPB- and hPB-supplemented groups by 31.9 ± 3.5% and 53.6 ± 3.2%, respectively, compared with the HSF group (P < 0.01), to concentrations comparable with the NF group. The wPB-supplemented hamsters had significantly lower liver cholesterol (45.1%, P < 0.001) and higher fecal cholesterol concentrations (94.8%, P = 0.001) than those fed the HSF. The expressions of hepatic 3-hydroxy-3-methylglutaryl CoA reductase (Hmgcr) and small intestinal acyl-coenzyme A: cholesterol acyltransferase 2 (Acat2) were significantly decreased in animals administered wPB (by 89.1% and 63.8%, respectively) and hPB (by 72.9% and 47.7%, respectively) compared with their HSF-fed counterparts (P < 0.05). The wPB normalized the expression of Acat2 to the level of the NF group. Conclusion Pinto beans remediated high cholesterol induced by HSF in male hamsters by decreasing hepatic cholesterol synthesis and intestinal cholesterol absorption, effects which were partially exerted by the hulls.


2014 ◽  
Vol 59 (No. 9) ◽  
pp. 391-398 ◽  
Author(s):  
T. Komprda ◽  
G. Zorníková ◽  
A. Knoll ◽  
Z. Vykoukalová ◽  
V. Rozíková ◽  
...  

A hypothesis that eicosapentaenoic acid + docosahexaenoic acid (EPA+DHA) lower plasma cholesterol via increased expression of the Insig-1 gene with ensuing decrease of expression of genes coding for 3-hydroxy-3-methyl-glutaryl-CoA reductase (Hmgcr) and low density lipoprotein receptor (Ldlr) was tested in rats fed a diet with 3% of fish oil (FO). Expression of the Insig-1 gene in the liver of the FO-fed rats was 730% (P &lt; 0.05) of the control. However, contrary to the hypothesis, expression of the Hmgcr gene and Ldlr gene was 165% and 210% of the control (P &gt; 0.05). Nevertheless, FO in the diet decreased (P &lt; 0.05) plasma cholesterol of rats by 10% (from 1.19 to 1.07 mmol/l); it was therefore concluded that the cholesterol-lowering effect of EPA+DHA is at least partly based on mechanisms other than tested in the present experiment. &nbsp;


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