Effect of Shuangyu Tiaozhi Decoction on SRB1/CYP7A1/FXR Signaling Pathway in Liver of Hypercholesterolemic Rats / 中国实验方剂学杂志

Objective:To observe the effect of Shuangyu Tiaozhi decoction on B-type scavenger receptor （SRB1）/cholesterol 7<italic>α</italic>-hydroxylase protein （CYP7A1）/farnesol X receptor （FXR） signaling pathway in liver of hypercholesterolemic rats， and its mechanism in reducing blood lipid. Method:Among 40 SD rats， 8 were randomly selected as normal group， and the remaining 32 were successfully established as hypercholesterolemic model， and randomly divided into 4 groups： model group， low and high-dose Shuangyu Tiaozhi decoction groups （7.8， 15.6 g·kg^-1）， and simvastatin group （4 mg·kg^-1）， with 8 rats in each group. The drugs were continuously given for 8 weeks. Serum total cholesterol （TC）， triglyceride （TG） and liver TC，free cholesterol （FC） and total bile acid （TBA） were measured. The pathomorphological changes in liver were observed by Hematoxylin and eosin （HE） Staining. The mRNA and protein expressions of SRB1， CYP7A1 and FXR were determined by Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR） and Western blot. The immunohistochemistry was used to detect CYP7A1 and FXR expressions in liver. Result:Compared with the normal group， TC， TG， FC levels in the model group were significantly increased， while the TBA level was markedly decreased， the morphology showed obvious liver steatosis， and significant declines in expressions of SRB1， CYP7A1， FXR were observed by Real-time PCR， Western blot and immunohistochemistry assays （<italic>P</italic><0.05， <italic>P</italic><0.01）. Compared with the model group， the levels of TC，TG，FC in each treatment group were reduced significantly， and the TBA level was increased markedly， the liver steatosis decreased significantly， the results of Real-time PCR， Western blot and immunohistochemistry assays showed significant increase in the expressions of SRB1， CYP7A1， FXR （<italic>P</italic><0.05， <italic>P</italic><0.01）. The therapeutic effect of high-dose Shuangyu Tiaozhi decoction group was more remarkable than that in low-dose Shuangyu Tiaozhi Decoction group （<italic>P</italic><0.05）， with no obvious difference compared with simvastatin group. Conclusion:Shuangyu Tiaozhi decoction can promote hepatic RCT and synthesize bile acid by up-regulating SRB1/CYP7A1/FXR signaling pathway， so as to reduce the blood lipid levels and improve hepatic lipid metabolism of hypercholesterolemic rats.

Study on anti-hyperlipidemia effect of Linderae Radix via regulating reverse cholesterol transport / 中国中药杂志

This article aims to investigate the ameliorative effect of Linderae Radix ethanol extract on hyperlipidemia rats induced by high-fat diet and to explore its possible mechanism from the perspective of reverse cholesterol transport(RCT). SD rats were divided into normal group, model group, atorvastatin group, Linderae Radix ethanol extract(LREE) of high, medium, low dose groups. Except for the normal group, the other groups were fed with a high-fat diet to establish hyperlipidemia rat models; the normal group and the model group were given pure water, while each administration group was given corresponding drugs by gavage once a day for five weeks. Serum total cholesterol(TC), triglyceride(TG), high density lipoprotein-cholesterol(HDL-c), low density lipoprotein-cholesterol(LDL-c), alanine aminotransferase(ALT), and aspartate aminotransferase(AST) levels were measured by automatic blood biochemistry analyzer; the contents of TC, TG, total bile acid(TBA) in liver and TC and TBA in feces of rats were detected by enzyme colorimetry. HE staining was used to observe the liver tissue lesions; immunohistochemistry was used to detect the expression of ATP-binding cassette G8(ABCG8) in small intestine; Western blot and immunohistochemistry were used to detect the expression of peroxisome proliferator-activated receptor gamma/aerfa(PPARγ/α), liver X receptor-α(LXRα), ATP-binding cassette A1(ABCA1) pathway protein and scavenger receptor class B type Ⅰ(SR-BⅠ) in liver. The results showed that LREE could effectively reduce serum and liver TC, TG levels, serum LDL-c levels and AST activity, and increase HDL-c levels, but did not significant improve ALT activity and liver index; HE staining results showed that LREE could reduce liver lipid deposition and inflammatory cell infiltration. In addition, LREE also increased the contents of fecal TC and TBA, and up-regulated the protein expressions of ABCG8 in small intestine and PPARγ/α, SR-BⅠ, LXRα, and ABCA1 in liver. LREE served as a positive role on hyperlipidemia model rats induced by high-fat diet, which might be related to the regulation of RCT, the promotion of the conversion of cholesterol to the liver and bile acids, and the intestinal excretion of cholesterol and bile acids. RCT regulation might be a potential mechanism of LREE against hyperlipidemia.

Serum lipids and lipoproteins: a brief review of the composition, transport and physiological functions

The dietary fats are composed primarily of triacylglycerols and some amount of phospholipids and cholesterol. Being hydrophobic in nature, these are insoluble in water, and hence cannot be transported in the blood plasma per se; to enable these lipids to be transported by the blood stream to various peripheral tissues, nature has devised the technique of making these soluble by binding them to proteins. These proteins involved in lipid transport are known as apolipoproteins, and the protein-lipid particle is known as lipoprotein. Thus, lipoproteins can be considered to be the primary transportmechanism to carry lipids from the alimentary tract to various parts of the body. Lipoproteins have gained prominence in medical field over the past few decades because of their role in the aetio-pathogenesis of cardiovascular diseases, principally atherosclerosis which is the cause of coronary artery disease and myocardial infarction. The various types and sub-types of lipoproteins have been found to have differing and even opposing roles in the development of arterial diseases. An understanding of the differing populations of lipoproteins, the associated proteins and other enzymes, and the myriad variety of inter-actions among themselves and with body cells is vital to our understanding the pathways involved in the development of cardio-vascular disordersand in determining the precise steps where pharmacological interventions can be introduced

Biochemistry and Molecular Biology of Mechanisms of Action of Fibrates – An Overview

Fibrates are a class ofmedication that mainly lowers theblood triglyceride levels. Theyreduce the LDL andincrease the levels of HDL C, in the blood.Clofibrate,the first member to bediscovered in 1962, and introduced in USA in 1967, is withdrawnin 2002, due to unexplained hepatomegaly,hepato-toxicity and possible risk of hepatic cancer. Other fibrates are introduced in the late 1970s and early1980s, such as gemfibrozil in the United States and bezafibrate and ciprofibrate in Europe. Their lipid lowering effects are found to decrease CVS risk , progression of atherosclerosis and metabolic syndrome, macrovascular and microvascular diabetic complications like stroke, myocardial infarction, peripheral vascular diseaseand diabeticretinopathy .Various clinical trials like VA-HIT trial (Veterans Affairs High-Density LipoproteinCholesterol Intervention Trial) , FIELD trail. (the Fenofibrate Intervention and Event Lowering in Diabetes) Helsinki Heart Study,ACCORD -Lipid trial (The lipid component of the Action to Control Cardiovascular Risk in Diabetes trial ) and BIP (Bezafibrate Infarction Prevention Study) trial andangiography trials, like LOCAT(LopidCoronary Angiography Trial) and BECLAIT(Bezafibrate Coronary Atherosclerosis Intervention Trial)demonstrated thebeneficial effects of gemfibrozil and fenofibrate.Their mechanism of action remained obscure for three decades,ie till 1990s, when theirmode of actionwas found. The Mechanism of action of fibrates include limitation of substrate availability for triglyceride synthesis in the liver, promotion of the action of lipoprotein lipase, (LPL)modulation of low density lipoprotein receptor/ligand interaction and stimulation of reverse cholesterol transport The biochemical and molecular mechanisms involvingthevariousenzymes like LCAT (Lecithin-cholesterol acyl transferase)andCYP7A1 etc. (cholesterol 7-alpha-monooxygenase or cytochromeP450 7A1 (CYP7A1)) , transporters like ABC , CETP (ATP-binding cassette transporter, Cholesterol ester binding protein) and NTCP,OATP (Na+-dependent taurocholate transporter/ organic anion transporters) . These are the.) andnuclear factors like LXR, PPAR alfa etc. (liver orphan receptorα , and peroxisome proliferative nuclear factor) , in relation to the mechanismsof action of fibrates are discussed . Areas of current interests in literature are briefed.

Catechins green tea upregulates the expression of ABCA1, ABCG1, and SRB1 in rats induced atherogenic diet

The efflux of cholesterol from macrophage to liver is known as reverse cholesterol transport (RCT). Impairedcholesterol efflux leads to cholesterol accumulation in macrophages. Therefore, how to increasing cholesterol effluxmay be an effective strategy for atherosclerosis prevention. Key molecules that play a vital role in the efflux ofcholesterol from macrophage are Adenosin Tri Phosphate (ATP)-binding casette transporters A1 and G. This study wasundertaken to clarify the effect of Catechins on the expression of specific transporters such as ATP-binding cassettesub-family A member 1 (ABCA1), ATP-binding cassette sub-family G member 1 (ABCG1) from macrophage to liver,and scavenger receptor class B type I (SRB1). This research was done on Wistar rats induced atherogenic diets. SRB1is one of the transporters to facilitate the delivery of cholesterol from the macrophage to the liver. The SRB1 pathwaymediated the selective uptake of cholesteryl ester. Catechins significantly increased the mRNA expression of ABCA1and ABCG1 in aorta as well as SRB1 of liver also increased. Thus, Catechins decreased the total cholesterol levels inaorta and serum. Catechins can be developed as a potential agent to increase ABCA1 to inhibit atherogenesis process.In conclusion, this study indicates that the potential anti-atherogenic properties of Catechins could be explained, atleast in part, as being due to upregulated expression of ABCA1, ABCG1, and SRB1 through activation liver X receptorsignaling pathway

Catechins green tea upregulates the expression of ABCA1, ABCG1, and SRB1 in rats induced atherogenic diet

The efflux of cholesterol from macrophage to liver is known as reverse cholesterol transport (RCT). Impairedcholesterol efflux leads to cholesterol accumulation in macrophages. Therefore, how to increasing cholesterol effluxmay be an effective strategy for atherosclerosis prevention. Key molecules that play a vital role in the efflux ofcholesterol from macrophage are Adenosin Tri Phosphate (ATP)-binding casette transporters A1 and G. This study wasundertaken to clarify the effect of Catechins on the expression of specific transporters such as ATP-binding cassettesub-family A member 1 (ABCA1), ATP-binding cassette sub-family G member 1 (ABCG1) from macrophage to liver,and scavenger receptor class B type I (SRB1). This research was done on Wistar rats induced atherogenic diets. SRB1is one of the transporters to facilitate the delivery of cholesterol from the macrophage to the liver. The SRB1 pathwaymediated the selective uptake of cholesteryl ester. Catechins significantly increased the mRNA expression of ABCA1and ABCG1 in aorta as well as SRB1 of liver also increased. Thus, Catechins decreased the total cholesterol levels inaorta and serum. Catechins can be developed as a potential agent to increase ABCA1 to inhibit atherogenesis process.In conclusion, this study indicates that the potential anti-atherogenic properties of Catechins could be explained, atleast in part, as being due to upregulated expression of ABCA1, ABCG1, and SRB1 through activation liver X receptorsignaling pathway.

Association between Waist Circumference and High-Density Lipoprotein Cholesterol in Korean Adults: Based on the Data of Korea National Health and Nutrition Examination Survey 2015

BACKGROUND: The aim of this study was searching for the orientation and degree of association, and receiver operating characteristic (ROC) curves between waist circumference (WC) and high-density lipoprotein cholesterol (HDL-C) of Korean adults for the new recommended WC values.METHODS: This study analyzed 5,069 Korean adults of the 2015 Korea National Health & Nutrition Examination Survey, using Pearson's correlation analysis, partial correlation analysis between WC and HDL-C with other significant variables to HDL-C controlled, and ROC curves.RESULTS: WC had the highest Pearson's correlation coefficient to HDL-C at −0.289 (P < 0.01) in men, and −0.318 (P < 0.01) in women. With other significant variables controlled, the partial correlation coefficient between WC and HDL-C became −0.250 (P < 0.001) in men and −0.191 (P < 0.001) in women. WC had the biggest area under the curve (AUC). For HDL-C≤40 mg/dL, the AUC values of WC were 0.633 (99% confidence interval [CI]: 0.600–0.666; P < 0.001) in men and 0.684 (99% CI: 0.648−0.719; P < 0.001) in women. For HDL-C≤60 mg/dL, the AUC values of WC were 0.654 (99% CI: 0.612–0.696; P < 0.001) in men and 0.661 (99% CI: 0.632–0.690; P < 0.001) in women.CONCLUSION: There was an inverse correlation between WC and HDL-C in Korean adults. While WC showed the strongest relation with HDL-C in both sexes, the scale of their interrelationship in men was larger if other significant variables were controlled. The new recommended WC values obtained by ROC curves of this study were ≤87.5 cm (better if ≤84.5 cm) in men, and ≤81.5 cm (better if ≤78.5 cm) in women.

Gypenoside granules improved lipid metabolism in C57BL/6J mice with hyperlipidemia / 中国药科大学学报

@#To investigate the hypolipidemic effects of gypenosides granules and its combination with lipitor, a model of hyperlipidaemia C57BL/6J mice was established by high-fat diet feeding for 4 weeks. The mice were randomly divided into blank group, model group, lipitor group(10 mg/kg of lipitor), low dose group(90 mg/kg of gypenosides granules), medium dose group(120 mg/kg of gypenosides granules), high dose group(180 mg/kg of gypenosides granules)and the combination group(180 mg/kg of gypenosides granules and 10 mg/kg of lipitor). After 4 weeks of continuous administration, the contents of serum lipid indexes, serum ALT, AST and apolipoprotein B(ApoB)were measured. The liver tissues of mice were observed by H&E staining. The expression levels of key factors involved in hepatic cholesterol metabolism were observed by RT-PCR and Western blot methods, such as adenosine triphosphate combined box transporter A1(ABCA1), liver X receptor(LXRα), cholesterol 7 alpha hydroxylase(CYP7A1)and type BΙ scavenger receptor(SR-BΙ). The results revealed that gypenosides granules significantly decreased the mice body weight, total abdominal fat area and the level of serum total cholesterol(TC). The combination group showed a more significant reduction in TC level than the other administration groups. Moreover, gypenosides granules treatment remarkably increased the protein expression of ABCA1 and up-regulated the mRNA expression of ABCA1, CYP7A1 and SR-BI. The above results suggest that gypenosides granules can significantly reduce blood lipid contents, and the combination therapy with lipitor show better the lipid-lowering effect. Meanwhile, gypenosides granules can decrease the level of serum transaminase. Preliminary exploration suggests the lipid-lowering mechanism of gypenosides granules may be involved in cholesterol reversal to regulate the level of TC.

Research progress in small molecule drugs based on high-density lipoprotein for anti-atherosclerosis / 药学学报

A large number of epidemiological data have shown that the high-density lipoprotein cholesterol level is negatively related to atherosclerotic cardiovascular disease, suggesting that high-density lipoprotein may have the effect of anti-atherosclerosis. It may play the role of anti-atherosclerosis, through the promotion of cholesterol reverse transport, anti-inflammatory, antioxidant, and against thrombosis and fibrinolysis and so on. Among them, reverse cholesterol transport which is mainly regulated by apolipoprotein A-I, ATP-binding cassette transporter 1, liver X receptor and cholesteryl ester transfer protein, may play a major role in the maintenance of cholesterol homeostasis and reversing the course of atherosclerosis. These regulatory factors may be potential targets in high density lipoprotein-based drug discovery. In this review, these key proteins are discussed for the current status of small molecule drugs against atherosclerosis.

The Role of Macrophage Lipophagy in Reverse Cholesterol Transport

Macrophage cholesterol efflux is a central step in reverse cholesterol transport, which helps to maintain cholesterol homeostasis and to reduce atherosclerosis. Lipophagy has recently been identified as a new step in cholesterol ester hydrolysis that regulates cholesterol efflux, since it mobilizes cholesterol from lipid droplets of macrophages via autophagy and lysosomes. In this review, we briefly discuss recent advances regarding the mechanisms of the cholesterol efflux pathway in macrophage foam cells, and present lipophagy as a therapeutic target in the treatment of atherosclerosis.

Effects and mechanism of different doses of rosuvastatin on expression of liver X receptor and caveolin-1 in cultured human monocyte-macrophage cells induced by oxidized low density lipoprotein / 中国综合临床

Objective To investigate the effects of different doses of rosuvastatin on expression of liver X receptor(LXR) and caveolin-1 in cultured human monocyte-macrophage cells which induced by oxidized low density lipoprotein (ox-LDL).Methods The human monocyte-macrophage cells were divided into six groups:control group,ox-LDL group,different doses of rosuvastatin group (0.01 μmol/L,0.1 μmol/L,1 μmol/L,5 μmol/L).The expression of LXR mRNA and caveolin-1 mRNA were assayed by RT-PCR.Results LXR mRNA expression induced by ox-LDL in the control group and ox-LDL group were 1.00 ± 0.02,0.26 ± 0.02,and the difference was significant (t =56.39,P ＜ 0.001).Meanwhile,caveolin-1 mRNA expression in ox-LDL is (0.27 ± 0.01) fold than that in control (t =31.27,P ＜ 0.001).Meanwhile,There were significant differences among ox-LDL group and the different doses of rosuvastatin group in terms of LXR mRNA and caveolin-1 mRNA expressions (F =72.154,66.007,P ＜ 0.001).Along with the increase the doses of rosuvastatin,there was an increased trends of LXR mRNA and caveolin-1 mRNA expressions (P ＜ 0.05).Conclusion Rosuvastatin and upregulated the LXR mRNA and caveolin-1 mRNA expressions in a dose dependent manner.

Study Progress in Apolipoprotein A-I's Gene Polymorphism and Its Relationship with Reverse Cholesterol Transport / 世界科学技术-中医药现代化

Apolipoprotein A-I (apoA-I) is a member of the apolipoprotein A family, which was discovered the earli-est. It has an important role in the regulation of lipid metabolism, which mainly includes cholesterol synthesis and transfer. Therefore, apoA-I is closely related to hyperlipidemia and atherosclerosis. Clinically, serum ApoA-I/ApoB has been used as one of the indexes of hyperlipidemia. This article reviewed the study progress in ApoA-I's gene polymorphism and its relationship with reverse cholesterol transport (RCT).

Endothelial Dysfunction: An Early Cardiovascular Risk Marker in Asymptomatic Obese Individuals with Prediabetes.

Aims: To elucidate if endothelial dysfunction is an early CV risk marker in obese men and women with prediabetes. Study Design: Cross-sectional study. Place and Duration of Study: Clinical Research Unit, Pennington Biomedical Research Center, Baton Rouge, LA. United States. Methodology: Overweight and obese status denotes an increasing adipose tissue burden which spills over into ectopic locations, including the visceral compartment, muscle and liver. Associated co-morbidities enhance cardiovascular (CV) risk. Endothelium which is the largest receptor-effector end-organ in our bodies, while responding to numerous physical and chemical stimuli maintains vascular homeostasis. Endothelial dysfunction (ED) is the initial perturbation, which precedes fatty streak known to initiate atherosclerosis: insidious process which often culminates as sudden catastrophic CV adverse event. Asymptomatic men and women; [n=42] coming in after an overnight fast had demographic, anthropometric, clinical chemistry and resting endothelial function [EF: increased test finger peripheral arterial tone (PAT) relative to control; expressed as relative hyperemia index (RHI)] assessments. Results: Adults with desirable weight [n=12] and overweight [n=8] state, had normal fasting plasma glucose [Mean(SD)]: FPG [91.1(4.5), 94.8(5.8) mg/dL], insulin [INS, 2.3(4.4), 3.1(4.8) μU/ml], insulin sensitivity by homeostasis model assessment [HOMA-IR, 0.62(1.2), 0.80(1.2)] and desirable resting clinic blood pressure [SBP/DBP, 118(12)/74(5), 118(13)/76(8) mmHg]. Obese adults [n=22] had prediabetes [FPG, 106.5(3.5) mg/dL], hyperinsulinemia [INS 18.0(5.2) μU/ml], insulin resistance [HOMA-IR 4.59(2.3)], prehypertension [PreHTN; SBP/DBP 127(13)/81(7) mmHg] and endothelial dysfunction [ED; reduced RHI 1.7(0.3) vs. 2.4(0.3); all p<0.05]. Age-adjusted RHI correlated with BMI [r=-0.53; p<0.001]; however, BMI-adjusted RHI was not correlated with age [r=-0.01; p=0.89]. Conclusion: Endothelial dysfunction reflective of cardiometabolic changes in obese adults can be an early risk marker for catastrophic CV events.

Efeito de hipolipemiantes sobre a expressão de genes envolvidos no transporte reverso do colesterol / Statin effects on expression of genes involved in reverse cholesterol transport

A eficácia das estatinas em reduzir o risco de eventos coronarianos não é completamente explicada por seus efeitos em diminuir colesterol de lipoproteína de baixa densidade (LDL-C). Um dos seus efeitos adicionais pode ser decorrente da modificação na concentração de lipoproteína de alta densidade (HDL), reconhecida como ateroprotetora, principalmente por seu papel no transporte reverso do colesterol (TRC). Os transportadores de membrana do tipo ATP-binding cassette, ABCA1 e ABCG1, e o scavenger receptor BI (SRBI) são proteínas importantes envolvidas no TRC e seus genes são regulados por vários fatores de transcrição, entre eles os liver-x-receptors (LXRs). Com a finalidade de avaliarmos os efeitos dos hipolipemiantes sobre expressão dos transportadores ABC e do receptor SRBI, a expressão de RNAm do ABCA1, ABCG1, SCARB1, NR1H3 (LXRα) e NR1H2 (LRXβ) foi avaliada por PCR em tempo real em células das linhagens HepG2 (origem hepática) e Caco-2 (origem intestinal) tratadas com atorvastatina ou sinvastatina (10 µM) e/ou ezetimiba (até 5 µM) por até 24 horas. Além disso, a expressão desses genes também foi avaliada em células mononucleares do sangue periférico (CMSP) de 50 pacientes normolipidêmicos (NL) e 71 hipercolesterolêmicos (HC) tratados com atorvastatina (10mg/dia/4semanas, n=48) ou sinvastatina e/ou ezetimiba (10mg/dia/4 ou 8 semanas, n=23). A possível associação entre os polimorfismos ABCA1 C-14T e R219K e a expressão de RNAm em CMSP também foi avaliada por PCR-RFLP. O SCARB1 foi o gene mais expresso nas células HepG2 e Caco-2, seguido por NR1H2, NR1H3, ABCG1 e ABCA1 em HepG2 ou por ABCA1 e ABCG1 em Caco-2. O tratamento com estatinas (1 ou 10 µM) ou ezetimiba (5 µM), por 12 ou 24 horas, aumentou a expressão de RNAm do ABCG1, mas não de ABCA1 e SCARB1, em células HepG2. Ainda nesta linhagem, o aumento na transcrição dos genes NR1H2 e NR1H3 foi observado somente com a maior concentração de atorvastatina (10 µM) e, ao contrário, o tratamento com ezetimiba...

The efficacy of statins in reducing the risk of coronary events is not completely explained by their effects in decreasing cholesterol low-density lipoprotein (LDL-C). One of their additional effects may result from the change in concentration of high-density lipoprotein (HDL), recognized as atheroprotective, mainly for the role in reverse cholesterol transport (RCT). The membrane transporters, as ATP-binding cassette, ABCA1 and ABCG1, and scavenger receptor BI (SRBI) are important proteins involved in the RCT and their genes are regulated by various transcription factors, including the liver-X-receptors (LXRs) . In order to evaluate the effects of lipid lowering on expression of ABC transporters and SRBI receptor, the mRNA expression of ABCA1, ABCG1, SCARB1, NR1H3 (LXRα) and NR1H2 (LRXβ) was assessed by real time PCR in HepG2 (hepatic origin) and Caco-2 (intestinal origin) cells treated with atorvastatin or simvastatin (10 µM) and/or ezetimibe (up to 5 µM) for 24 hours. Furthermore, the expression of these genes was evaluated in peripheral blood mononuclear cells (PBMC) of 50 normolipidemic (NL) and 71 hypercholesterolemic (HC) patients treated with atorvastatin (10mg/d/4 weeks, n = 48) or simvastatin and/or ezetimibe (10mg/d/4 or 8 weeks, n = 23). The possible association between ABCA1 C-14T and R219K polymorphisms and mRNA expression in PBMC was also evaluated by PCR-RFLP. SCARB1 was the most expressed in HepG2 and Caco-2 cells, followed by NR1H2, NR1H3, ABCG1 and ABCA1 in HepG2 or by ABCG1 and ABCA1 in Caco-2. The treatment with statins (1 or 10 µM) or ezetimibe (5 µM) for 12 or 24 hours, increased mRNA expression of ABCG1 but not ABCA1 and SCARB1 in HepG2 cells. Moreover, in HepG2 cells, atorvastatin also upregulated NR1H2 and NR1H3 only at 10.0 µM, meanwhile ezetimibe downregulated NR1H2 but did not change NR1H3 expression. In Caco-2 cells, atorvastatin or simvastatin treatment for 12 or 24 hours reduced the amount of ABCA1 transcript and did not ...

Efeito de hipolipemiantes sobre a expressão de genes envolvidos no transporte reverso do colesterol / Statin effects on expression of genes involved in reverse cholesterol transport

A eficácia das estatinas em reduzir o risco de eventos coronarianos não é completamente explicada por seus efeitos em diminuir colesterol de lipoproteína de baixa densidade (LDL-C). Um dos seus efeitos adicionais pode ser decorrente da modificação na concentração de lipoproteína de alta densidade (HDL), reconhecida como ateroprotetora, principalmente por seu papel no transporte reverso do colesterol (TRC). Os transportadores de membrana do tipo ATP-binding cassette, ABCA1 e ABCG1, e o scavenger receptor BI (SRBI) são proteínas importantes envolvidas no TRC e seus genes são regulados por vários fatores de transcrição, entre eles os liver-x-receptors (LXRs). Com a finalidade de avaliarmos os efeitos dos hipolipemiantes sobre expressão dos transportadores ABC e do receptor SRBI, a expressão de RNAm do ABCA1, ABCG1, SCARB1, NR1H3 (LXRα) e NR1H2 (LRXß) foi avaliada por PCR em tempo real em células das linhagens HepG2 (origem hepática) e Caco-2 (origem intestinal) tratadas com atorvastatina ou sinvastatina (10 µM) e/ou ezetimiba (até 5 µM) por até 24 horas. Além disso, a expressão desses genes também foi avaliada em células mononucleares do sangue periférico (CMSP) de 50 pacientes normolipidêmicos (NL) e 71 hipercolesterolêmicos (HC) tratados com atorvastatina (10mg/dia/4semanas, n=48) ou sinvastatina e/ou ezetimiba (10mg/dia/4 ou 8 semanas, n=23). A possível associação entre os polimorfismos ABCA1 C-14T e R219K e a expressão de RNAm em CMSP também foi avaliada por PCR-RFLP. O SCARB1 foi o gene mais expresso nas células HepG2 e Caco-2, seguido por NR1H2, NR1H3, ABCG1 e ABCA1 em HepG2 ou por ABCA1 e ABCG1 em Caco-2. O tratamento com estatinas (1 ou 10 µM) ou ezetimiba (5 µM), por 12 ou 24 horas, aumentou a expressão de RNAm do ABCG1, mas não de ABCA1 e SCARB1, em células HepG2. Ainda nesta linhagem, o aumento na transcrição dos genes NR1H2 e NR1H3 foi observado somente com a maior concentração de atorvastatina (10 µM) e, ao contrário, o tratamento com ezetimiba causou redução na transcrição de NR1H2, sem alteração de NR1H3. Em células Caco-2, o tratamento com atorvastatina ou sinvastatina por 12 ou 24 horas reduziu a quantidade do transcrito ABCA1 e não alterou a expressão do SCARB1 e do ABCG1, embora, para este último, tenha havido uma tendência à diminuição da expressão após tratamento com sinvastatina (p=0,07). Após tratamento com ezetimiba isolada (até 5 µM) nenhuma alteração de expressão de RNAm foi observada em células Caco-2; no entanto, após 24 horas de tratamento com sinvastatina e ezetimiba, foi reduzida a taxa de transcrição de ABCA1 e ABCG1, mas não de SCARB1. Ao contrário das linhagens celulares, em CMSP os genes NR1H2 e ABCG1 foram os mais expressos, seguidos pelos genes SCARB1 e ABCA1 e, finalmente, pelo NR1H3. Indivíduos HC tiveram maior expressão basal de NR1H2 e NR1H3, mas não de outros genes, quando comparados aos NL (p<0,05). Além disso, nos indivíduos HC, a expressão basal de ABCA1 foi maior em portadores do alelo -14T do polimorfismo ABCA1 -14C>T quando comparados aos portadores do genótipo -14CC (p=0,034). O tratamento com estatinas, com ezetimiba ou com a terapia combinada diminuiu a transcrição de ABCA1 e ABCG1. Para o SCARB1, NR1H2 e NR1H3, nenhuma alteração de expressão de RNAm em CMSP foi detectada após os tratamentos in vivo. Após todas as fases de tratamento, ABCA1 e ABCG1 e também NR1H2 e NR1H3 foram significativamente correlacionados entre si, mas nenhuma correlação com perfil lipídico sérico foi relevante. Coletivamente, esses resultados dão indícios de que os hipolipemiantes analisados (estatinas e ezetimiba) têm um importante papel na regulação da expressão de genes envolvidos no transporte reverso do colesterol e sugerem a existência de regulação tecido-específica para os dois transportadores ABC. Além disso, o efeito das estatinas ou da ezetimiba sobre a expressão do ABCA1, do ABCG1 ou do SCARB1 não sofreu influencia de alterações diretas da transcrição dos LXRs

The efficacy of statins in reducing the risk of coronary events is not completely explained by their effects in decreasing cholesterol low-density lipoprotein (LDL-C). One of their additional effects may result from the change in concentration of high-density lipoprotein (HDL), recognized as atheroprotective, mainly for the role in reverse cholesterol transport (RCT). The membrane transporters, as ATP-binding cassette, ABCA1 and ABCG1, and scavenger receptor BI (SRBI) are important proteins involved in the RCT and their genes are regulated by various transcription factors, including the liver-X-receptors (LXRs) . In order to evaluate the effects of lipid lowering on expression of ABC transporters and SRBI receptor, the mRNA expression of ABCA1, ABCG1, SCARB1, NR1H3 (LXRα) and NR1H2 (LRXß) was assessed by real time PCR in HepG2 (hepatic origin) and Caco-2 (intestinal origin) cells treated with atorvastatin or simvastatin (10 µM) and/or ezetimibe (up to 5 µM) for 24 hours. Furthermore, the expression of these genes was evaluated in peripheral blood mononuclear cells (PBMC) of 50 normolipidemic (NL) and 71 hypercholesterolemic (HC) patients treated with atorvastatin (10mg/d/4 weeks, n = 48) or simvastatin and/or ezetimibe (10mg/d/4 or 8 weeks, n = 23). The possible association between ABCA1 C-14T and R219K polymorphisms and mRNA expression in PBMC was also evaluated by PCR-RFLP. SCARB1 was the most expressed in HepG2 and Caco-2 cells, followed by NR1H2, NR1H3, ABCG1 and ABCA1 in HepG2 or by ABCG1 and ABCA1 in Caco-2. The treatment with statins (1 or 10 µM) or ezetimibe (5 µM) for 12 or 24 hours, increased mRNA expression of ABCG1 but not ABCA1 and SCARB1 in HepG2 cells. Moreover, in HepG2 cells, atorvastatin also upregulated NR1H2 and NR1H3 only at 10.0 µM, meanwhile ezetimibe downregulated NR1H2 but did not change NR1H3 expression. In Caco-2 cells, atorvastatin or simvastatin treatment for 12 or 24 hours reduced the amount of ABCA1 transcript and did not alter the ABCG1 and SCARB1 expressions, despite the tendency to decrease ABCG1 mRNA expression after simvastatin treatment (p = 0.07). After treatment with ezetimibe alone (up to 5 µM) no change in mRNA expression was observed in Caco-2 cells; however, after 24 hours- simvastatin and ezetimibe treatments decreased the transcription of ABCA1 and ABCG1, but not of SCARB1. Unlike cell lines, in PBMC, NR1H2 and ABCG1 were the most expressed, followed by SCARB1 and ABCA1 and finally by the NR1H3. HC patients showed higher NR1H2 and NR1H3 basal expressions, but not of other genes, compared to NL (p <0.05). Moreover, in HC individuals, the ABCA1 basal expression was higher in individuals carrying -14T allele of -14C> T polymorphism when compared with -14CC carriers (p = 0.034). Treatment with statins, ezetimibe, or combined therapy downregulated ABCA1 and ABCG1 expression. For SCARB1, NR1H2 and NR1H3, no change in mRNA expression in PBMC was detected after treatments. After all phases of treatment, ABCA1 and ABCG1 as well as NR1H2 and NR1H3 were significantly correlated, but no correlation with serum lipid profile was relevant. Collectively, these results provide evidences that the lipid lowering (statins and ezetimibe) have an important role in mRNA expression regulation of genes involved in reverse cholesterol transport and suggest the existence of tissue-specific regulation for the ABC transporters. Furthermore, the effect of statins or ezetimibe on ABCA1, ABCG1 or SCARB1 expression was not directly influenced by changes of LXR transcription

HDL: o yin-yang da doença cardiovascular / HDL: the yin-yang of cardiovascular disease

Estudos epidemiológicos mostram relação inversa entre níveis plasmáticos de HDL-colesterol (HDL-C) e incidência de doença cardiovascular (DCV). O papel antiaterogênico da HDL é atribuído às suas atividades anti-inflamatória, antitrombótica e antioxidante, além de sua participação no transporte reverso de colesterol (TRC), processo pelo qual a HDL remove colesterol dos tecidos periféricos, incluindo macrófagos da íntima arterial, e o transporta para o fígado para ser excretado pela bile. Com base nesses fatos, o HDL-C tornou-se alvo atrativo para a prevenção da DCV. No entanto, o fracasso do torcetrapib, droga que aumenta substancialmente os níveis de HDL-C, em prevenir DCV, além do conhecimento gerado por estudos de modelos animais e doenças monogênicas que afetam a concentração de HDL-C, tem suscitado questionamentos sobre o papel antiaterogênico da HDL. Esta revisão tem como objetivo abordar aspectos atuais do conhecimento da HDL, baseando-se nessas recentes controvérsias.

Epidemiological studies demonstrate an inverse correlation between plasma HDL-cholesterol (HDL-C) concentration and incidence of cardiovascular disease (CVD). The antiatherogenic role of HDL has been attributed to its anti-inflammatory, antithrombotic and antioxidant properties, besides its participation in the reverse cholesterol transport (RCT), whereby cholesterol from peripheral tissues (including macrophages of the arterial intima) is delivered to the liver for excretion in bile. Due to these actions, HDL-C has evolved as an attractive target for prevention of CVD. However, the failure of torcetrapib, drug that substantially increases HDL-C levels, in preventing CVD and data from studies with animal models and with carriers of monogenic disorders affecting HDL-C levels in humans provide conflicting data about HDL being antiatherogenic. This review addresses the current state of knowledge regarding HDL based on these recent controversies.

A Possible Mechanism Linking Hyperglycemia and Reduced High-density Lipoprotein Cholesterol Levels in Diabetes / 华中科技大学学报（医学）（英德文版）

This study investigated the role of glucose in the biogenesis of high-density lipoprotein cholesterol(HDL-C).Mouse primary peritoneal macrophages were harvested and maintained in Dulbecco's modified Eagle's medium(DMEM)containing glucose of various concentrations.The cells were divided into 3 groups in terms of different glucose concentrations in the cultures:Control group (5.6 mmol/L glucose),high glucose concentration groups(16.7 mmol/L and 30 mmol/L glucose).ATP-bindmg cassette transporter A1(ABCA1)mRNA expression in the macrophages was detected by semi-quantitative RT-PCR 24,48 and 72 h after glucose treatment.The results showed that ABCA1 mRNA expression in the 16.7 mmol/L glucose group was not significantly different from that in the control group at all testing time points(P＞0.05 for each).In the 30 mmol/L glucose group,macrophage ABCA1 mRNA expression was not changed significantly at 24 h(P=0.14),but was substantially decreased by 40.4% at 48 h(P=0.009)and by 48.1% at 72 h(P=0.015)as compared with that in the control group.It was concluded that ABCA1 is of vital importance for HDL-C biogenesis.High glucose may hamper HDL-C biogenesis by decreasing ABCA1 expression,which contributes to low HDL-C level in diabetes.

Ácido linoleico conjugado (ALC), metabolismo de lípidos y enfermedad cardiovascular / Conjugated linoleic acid (ALC), lipid metabolism and cardiovascular disease

High density lipoproteins (HDL) have been inversely related with the risk of cardiovascular diseases and are considered antiatherogenic factors. The vascular protective effect of HDL is associated to the reverse cholesterol transport, where the sterol is mobilized from peripheral tissues to the liver by HDL and redistributed to circulation or delivered through the bile as free cholesterol or transformed into bile acids. In the last years it has been demonstrated that conjugated linoleic acid (CLA), an omega-6 fatty acid from ruminants, which is a mixture of positional and geometric isomers of linoleic acid, has hipolipidemic and antiatherogenic properties in animal models. However, the precise effect of CLA on HDL metabolism and the mechanisms involved in these actions have yet not been elucidated. The present work reviews the scientific literature about the possible role of CLA as an antiatherogenic factor by controlling the reverse cholesterol transport.

Las lipoproteínas de alta densidad (HDL) han sido correlacionadas inversamente con el riesgo de enfermedad cardiovascular ya que se considera que constituyen un factor de protección antiateroesclerótico. El efecto protector vascular de las HDL se asocia con la vía de transporte reverso de colesterol, proceso por el cual el esterol es movilizado desde los tejidos periféricos hacia el hígado a través de las HDL plasmáticas para ser redistribuido a la circulación, o para su remoción hacia la bilis como colesterol propiamente tal o transformado en sales biliares. Por otro lado, en los últimos a±os el ácido linoleico conjugado (ALC), un acido graso derivado de la serie omega-6 proveniente de animales rumiantes y cuya mezcla está mayoritariamente formada por los isómeros geométricos y posicionales del ácido linoleico (cis 9 trans 11 y trans 10 cis 12), ha demostrado tener propiedades hipolipemiantes y antiaterogénicas en varios modelos animales. Sin embargo, su efecto preciso sobre el metabolismo de HDL y los posibles mecanismos de acción involucrados aún no ha sido dilucidado. El presente trabajo realiza una revisión de la literatura científica en relación al rol antiaterosclerótico que puede tener el consumo de ALC a través del control del trasporte reverso del colesterol.

Probucol promotes reverse cholesterol transport from macrophage to feces in mice in vivo / 中国药理学通报

Aim To investigate the effect of probucol on reverse cholesterol transport from macrophage to feces in vivo,serum lipid profiles of mice were tested before and after probucol administration for 4 weeks,and the 3H-contents in serum,liver and feces in mice were quantitated after 24 hours intraperitoneally injected macrophages which were labeled with 3H cholesterol.Methods 32 C57BL/6 mice were treated with different probucol(0,0.1%,0.5%,1% W/W)in chow diet for 4 weeks,then these mice were injected intraperitoneally with RAW264.7 macrophages(0.5 ml?mice,cells 5.0?106 with 6.2?106 cpm)which were loaded with cholesterol by incubation with acetylated LDL,labeled with 3H-cholesterol.Serum profiles were quantitated by enzymatic method;serum and liver tissues were harvested at 24th hour,feces were collected(0~24 hs),and all were analyzed for tracer counts(all were expressed as the percentage of the total injected counts per minute).Results After 4 weeks 0.1% probucol administration,the levels of total cholesterol(TC),high-density lipoprotein cholesterol(HDL-C)decreased markedly by 34.3%,52.8%,(P

Progress in new drugs targeting reverse cholesterol transport / 中国药理学通报

Numerous epidemiologic studies have shown that there is a strong inverse relationship between high-density lipoprotein cholesterol levels and artherosclerosis. The first atheroprotective mechanism of HDL is the RCT(reverse cholesterol transport). Recently,considerable pharmacological trials have focused on targeting critical proteins and enzymes in RCT including apoAⅠ, ATP binding cassette transporter A1 and cholesteryl ester transport protein etc. A number of new drugs have demonstrated conspicuous protective effects on artherosclerosis. Therefore RCT will become an attractive target for prevention and cure of dyslipidamia and artherosclerosis.