Pravastatin activates the expression of farnesoid X receptor and liver X receptor alpha in Hep3B cells

BACKGROUND: Statins are suggested to preserve gallbladder function by suppressing pro-inflammatory cytokines and preventing cholesterol accumulation in gallbladder epithelial cells. They also affect cross-talk among the nuclear hormone receptors that regulate cholesterol-bile acid metabolism in the nuclei of hepatocytes. However, there is controversy over whether or how statins change the expression of peroxisome proliferator-activated receptor(PPAR)α, PPARγ, liver X receptor α(LXRα), farnesoid X receptor(FXR), ABCG5, ABCG8, and 7α-hydroxylase(CYP7A1) which are directly involved in the cholesterol saturation index in bile. METHODS: Human Hep3B cells were cultured on dishes. MTT assays were performed to determine the appropriate concentrations of reagents to be used. The protein expression of PPARα and PPARγ was measured by Western blotting analysis, and the mRNA expression of LXRα, FXR, ABCG5, ABCG8 and CYP7A1 was estimated by RT-PCR. RESULTS: In cultured Hep3B cells, pravastatin activated PPARα and PPARγ protein expression, induced stronger expression of PPARγ than that of PPARα, increased LXRα mRNA expression, activated ABCG5 and ABCG8 mRNA expression mediated by FXR as well as LXRα, enhanced FXR mRNA expression, and increased CYP7A1 mRNA expression mediated by the PPARγ and LXRα pathways, together or independently. CONCLUSION: Our data suggested that pravastatin prevents cholesterol gallstone diseases via the increase of FXR, LXRαand CYP7A1 in human hepatocytes.

Liver X receptors and epididymal epithelium physiology

Aim： To investigate the roles of liver X receptors （LXR） in the lipid composition and gene expression regulation in the murine caput epididymidis. LXR are nuclear receptors for oxysterols, molecules derived from cholesterol metabolism that are present in mammals as two isoforms： LXRα, which is more specifically expressed in lipid-metabolising tissues, such as liver, adipose and steroidogenic tissues, and macrophages, whereas LXRβ is ubiquitous. Their importance in reproductive physiology has been sustained by the fact that male mice in which the function of both LXR has been disrupted have fertility disturbances starting at the age of 5 months, leading to complete sterility by the age of 9 months. These defects are associated with epididymal epithelial degeneration in caput segments one and two, and with a sperm midpiece fragility, leading to the presence of isolated sperm heads and flagella when luminal contents are recovered from the cauda epididymidis. Methods： The lipid composition of the caput epididymidis of wild-type and LXR-deficient mice was assessed using oil red O staining on tissue cryosections and lipid extraction followed by high performance liquid chromatography or gas chromatography. Gene expression was checked by quantitative real time polymerase chain reaction. Results： Using LXR-deficient mice, we showed an alteration of the lipid composition of the caput epididymidis as well as a significantly decreased expression of the genes encoding SREBPlc, SCD1 and SCD2, involved in fatty acid metabolism. Conclusion： Altogether, these results show that LXR are important regulators of epididymal function, and play a critical role in the lipid maturation processes occurring during sperm epididymal maturation. （Asian J Androl 2007 July; 9： 574-582）

Role of liver X receptors alpha agonist on expressions of LPS-induced inflammatory response associated factor IRAK-4 and NF-kappaB in Kupffer cells

Objective： To explore the role of activated liver X receptor α （LXRα） on the expressions of interleukin-1 receptor associated kinase-4 （IRAK-4） and NF-kappaB （NF-κB） in the inflammatory response which induced by LPS in the Kupffer cells and to investigate the possible mechanisms of LXRα negative regulation of inflammatory response. Methods： The Kupffer cells were isolated from male Kunming mice by collagen perfusion in situ. And these cells were divided into 4 groups： normal control group, LPS treatment group, LXRct agonist T0901317 treatment group, LPS and T0901317 combined treatment group. The LPS treatment group were treated with a final concentration of 1 μg/ml LPS in RPMI 1640 and cultured for 6 h, the T0901317 treatment group were treated with a final concentration of 5 μg/ml in RPMI 1640 and cultured for 24 h, and the combined treatment group received pre-culture for 24 h with a final concentration of 1μg/ml T0901317 in RPMI 1640 and then cultured for 6 h with a final concentration of 5 μg/ml LPS in RPMI 1640. All groups were cultured for 30 h. The expression of LXRα, IRAK-4 and NF-κB at mRNA and protein levels were detected by real-time PCR and Western blotting, and the TNF-α and IL-1β levels were detected by ELISA. Results： The levels of LXRα mRNA and protein were highest in T0901317 group, and lowest in LPS group （P〈0.05）. The level of IRAK4 and NF-κB mRNAs and proteins were evidently lower in the Combined-treated group than in LPS group （P〈0.05）. And the level of TNF-α and IL-1 were observed highest in LPS group （P〈0.05）, but no difference among the Control group, T0901317 group and Combined-treated group （P〉0.05）. Conclusion： These date suggest that the LXR agonists can effectively up-regulate the expressions of LXRα mRNA and protein and inhibit the inflammatory response. This may be via down-regulating the expressions of IRAK4 and NF-κB at mRNA and protein levels.

Coronary heart disease:Significance of liver X receptor α genomics

Crosstalk between lipid peroxidation and inflammation is known to be a pathognomonic feature for the development of coronary heart disease(CHD).In this regard ligand activated liver X receptor(LXR)-α has emerged as a key molecular switch by its inherent ability to modulate an array of genes involved in these two fundamental cellular processes.In addition,LXR-α has also been found to play a role in hepatic lipogenesis and innate immunity.Although several lines of evidence in experimental model systems have established the atheroprotective nature of LXR-α,human subjects have been reported to possess a paradoxical situation in which increased blood cellular LXR-α gene expression is always accompanied by increased coronary occlusion.This apparent paradox was resolved recently by the finding that CHD patients possess a deregulated LXR-α transcriptome due to impaired ligand-receptor interaction.This blood cellular mutated LXR-α gene ex- pression correlated specifically with the extent of coro- nary occlusion and hence need is felt to devise new synthetic ligands that could restore the function of this mutated LXR-αprotein in order to modulate genes involved in reverse cholesterol transport and suppression of the inflammatory response leading to the effective treatment of CHD.

Natural modulators of liver X receptors

Nuclear receptor transcription factors are ligand-activated proteins that control various biological events from cell growth and development to lipid metabolism, and energy and glucose homeostasis. Nuclear receptors are important drug targets for metabolic diseases. Liver X receptors （LXRs） are nuclear receptor transcription factors that play essential roles in regulation of cholesterol, triglyceride, fatty acid, and glucose homeostasis. LXR-deficient mice have shown the association of LXR-signaling pathway dysfunction with several human pathologies including atherosclerosis, hyperlipidemia, Alzheimer s disease and cancer. Thus, LXRs are promising pharmacological targets for these diseases. Synthetic LXR agonists may lower cholesterol, but increase triglyceride and induce fatty liver. The naturally occurring LXR ligands, with moderate activity, may serve as nutraceuticals for prevention or treatment of the disorders, while minimizing potential side effects. In this review, recent advances in natural LXR modulators are summarized including agonist, antagonist and the modulator of LXR pathway.

Effect of Dangfei Liganning capsule(当飞利肝宁胶囊) on liver X receptor α/steroid regulatory element binding protein-1/fatty acid synthase signal pathway in rats with metabolic-associated fatty liver disease

OBJECTIVE: To study the mechanism of Dangfei Liganning capsule(当飞利肝宁胶囊) in the treatment of rats with metabolic associated fatty liver disease(MAFLD). METHODS: Totally 48 specific pathogen free SpragueDawley male rats were randomly divided into normal Group, model group, Dangfei Liganning high, moderate, and low-dose groups and Essentiale group which were fed with high fat diet for 8 weeks, and gavage and molding were carried out simultaneously. Dangfei Liganning high, middle and low-dose group were given 0.27, 0.135 and 0.0675 g·kg-1·d-1 respectively by gavage, Essentiale group was given 0.123 g·kg-1·d-1 by gavage, the same amount of distilled water was given by gavage in the normal group and the model group. The rats were weighed at the 0th week, 2nd week, 4th week, 6th week and 8th weekend respectively. The rats were sacrificed at the end of the 8th week. Serum levels of alanine aminotransferase(ALT), alanine aminotransferase(AST),triglyceride(TG), total cholesterol(CHO), high-density lipoprotein cholesterol(HDL-C), low-density lipoprotein (LDL-C), total protein(TP), albumin(Alb), globulin(GLB), total bilirubin(TBIL), direct bilirubin(DBIL), tumor necrosis factor-α(TNF-α) and interleukin-6(IL-6) were measured. The levels of liver tumor necrosis factor-α(TNF-α), interleukin-6(IL-6) and liver pathology [hematoxylin and eosin(HE) staining, oil red O staining] were detected. The expression levels of liver X receptor α(LXRα), steroid regulatory element binding protein-1(SREBP-1) and fatty acid synthase(FAS) were detected by immunohistochemistry, Western blot and reverse transcription-polymerase chain reaction reverse transcription-polymerase chain reaction. RESULTS: From the beginning to the 8th week, the growth rate of body weight in the Dangfei Liganning highdose group was slower than all other groups. There was no significant difference in ALB level in all groups(P > 0.05). Compared with the model group, the levels of ALT, AST, LDL-C, TG, CHO, TP, GLB, TBIL, DBIL, IL-6, TNF-α were significantly decreased and HDL-C were significantly increased in Dangfei Liganning high-dose group(P < 0.01, < 0.05). HE and oil red O staining showed that the fatty lesions in rat liver were alleviated, while the expressions of LXRα, SREBP-1, FAS m RNA and protein were significantly decreased(P < 0.01). CONCLUSIONS: Dangfei Liganning capsule can slow down the increase of body weight of MAFLD rats, reduce the levels of transaminase, Lipid and inflammatory factors in MAFLD rats, promote the synthesis of liver protein and bile metabolism, and improve the liver fatty lesion of MAFLD rats, among which the Dangfei Liganning highdose group is more effective. The mechanism of action may be through blocking LXR-SREBP-1-FAS signal pathway.

ATF4/TXNIP/REDD1/mTOR signaling mediates the antitumor activities of liver X receptor in pancreatic cancers

Background:Limited by difficulties in early detection and availabilities of effective treatments,pancreatic cancer is a highly malignant disease with poor prognosis.Nuclear receptors are a family of ligand‐dependent transcription factors that are highly druggable therapeutic targets playing critical roles in human physiological and pathological development,including cancer.In this study,we explored the therapeutic potential as well as the molecular mechanisms of liver X receptor(LXR)agonist GW3965 in pancreatic cancer.Methods:Soft‐agar colony formation assay,xenograft tumors,Oligonucleotide microarray,Reverse transcription real‐time polymerase chain reaction,Western immunoblotting and Immunohistochemistry were used in this study.Results:We demonstrated pleotropic in vitro activities of GW3965 in pancreatic cell lines MIA PaCa‐2 and BXPC3 including reduction of cell viability,inhibition of cell proliferation,stimulation of cell death,and suppression of colony formation,which translated to significant inhibition of xenograft tumor growth in vitro.By mapping the gene expression profiles,we identified the up‐regulations of 188 and the down‐regulations of 92 genes common to both cell lines following GW3965 treatment.Genes responsive to GW3965 represent a variety of biological pathways vital for multiple cellular functions.Specifically,we identified that the activating transcription factor 4/thioredoxin‐interacting protein/regulated in development and DNA damage responses 1/mechanistic target of rapamycin(ATF4/TXNIP/REDD1/mTOR)signaling critically controls GW3965‐mediated regulation of cell proliferation/death.The significance of the ATF4/TXNIP/REDD1/mTOR pathway was further supported by associated expressions in xenograft tumors as well as human pancreatic cancer samples.Conclusions:This study provides the pre‐clinical evidence that LXR agonist is a promising therapy for pancreatic cancer.

Liver as a new target organ in Alzheimer's disease:insight from cholesterol metabolism and its role in amyloid-beta clearance

Alzheimer's disease,the primary cause of dementia,is characterized by neuropathologies,such as amyloid plaques,synaptic and neuronal degeneration,and neurofibrillary tangles.Although amyloid plaques are the primary characteristic of Alzheimer's disease in the central nervous system and peripheral organs,targeting amyloid-beta clearance in the central nervous system has shown limited clinical efficacy in Alzheimer's disease treatment.Metabolic abnormalities are commonly observed in patients with Alzheimer's disease.The liver is the primary peripheral organ involved in amyloid-beta metabolism,playing a crucial role in the pathophysiology of Alzheimer's disease.Notably,impaired cholesterol metabolism in the liver may exacerbate the development of Alzheimer's disease.In this review,we explore the underlying causes of Alzheimer's disease and elucidate the role of the liver in amyloid-beta clearance and cholesterol metabolism.Furthermore,we propose that restoring normal cholesterol metabolism in the liver could represent a promising therapeutic strategy for addressing Alzheimer's disease.

Liver X receptor agonist T0901317 reduces atherosclerotic lesions in apoE^(-/-) mice by up-regulating NPC1 expression

In this study, we studied the effect of liver X receptor (LXR) agonist T0901317 on Niemann-Pick C1 protein (NPC1) expression in apoE-/- mice. Male apoE-/- mice were randomized into 4 groups, baseline group (n=10), control group (n=14), treatment group (n=14) and prevention group (n=14). All of the mice were fed with a high-fat/high-cholesterol (HFHC) diet containing 15% fat and 0.25% cholesterol. The baseline group treated with vehicle was sacrificed after 8 weeks of the diet. The control group and the prevention group were treated with either vehicle or T0901317 daily by oral gavage for 14 weeks. The treatment group was treated with vehicle for 8 weeks, and then was treated with the agonist T0901317 for additional 6 weeks. Gene and protein expression was analyzed by real-time quantitative PCR, immunohistochemistry and Western blotting, respectively. Plasma lipid concentrations were measured by commercially enzymatic methods. We used RNA interference technology to silence NPC1 gene expression in THP-1 macrophage-derived foam cells and then detected the effect of LXR agonist T0901317 on cholesterol efflux. Plasma triglyceride (TG), total cholesterol (TC), high density lipoprotein cholesterol (HDL-C) and apoA-I concentrations were markedly increased in T0901317-treated groups. T0901317 treatment reduced the aortic atherosclerotic lesion area by 64.2% in the prevention group and 58.3% in the treatment group. LXR agonist treatment increased NPC1 mRNA expression and protein levels in the small intestine, liver and aorta of apoE-/- mice. Compared with the normal cells, cholesterol efflux of siRNA THP-1 macrophage-derived foam cells was significantly decreased, whereas cholesterol efflux of LXR agonist T0901317-treated THP-1 macrophage-derived foam cells was significantly increased. Our results suggest that LXR agonist T0901317 inhibits atherosclerosis development in apoE-/- mice, which is related to up-regulating NPC1 expression.

Recent insights into farnesoid X receptor in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease(NAFLD) is the hepatic manifestation of metabolic syndrome and is one of the most prevalent liver disorders worldwide. NAFLD can gradually progress to liver inflammation, fibrosis, cirrhosis and even hepatocellular carcinoma. However, the pathogenesis of NAFLD is complex, and no efficient pharmaceutic treatments have yet been established for NAFLD. Accumulating data have shown that the farnesoid X receptor(FXR) plays important roles not only in bile acid metabolism, but also in lipid and carbohydrate homeostasis, inflammatory responses, among others. In this review, we aim to highlight the role of FXR in the pathogenesis and treatment of NAFLD.

基于FXR/SHP/PEPCK和FXR/ApoCⅡ通路探讨茵陈五苓散对代谢相关脂肪性肝病大鼠糖脂代谢的作用

目的:基于法尼醇X受体(FXR)/微小异源二聚体(SHP)/磷酸烯醇式丙酮酸羧激酶(PEPCK)和FXR/载脂蛋白CⅡ(ApoCⅡ)通路探讨茵陈五苓散对代谢相关脂肪性肝病(MAFLD)大鼠糖脂代谢的作用。方法:用高脂饮食建立MAFLD大鼠模型,将成模大鼠随机分为模型组、茵陈五苓散高剂量组、茵陈五苓散低剂量组和辛伐他汀组,并选取同批次未进行造模处理的大鼠作为空白组。各组给予相应药物和0.9%氯化钠溶液干预4周。灌胃期间每周定时检测各组大鼠的体重和空腹血糖(FBG);生化法检测总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)、谷丙氨酸氨基转移酶(ALT)及天冬氨酸氨基转移酶(AST)水平;ELISA法检测胰岛素(FINS)水平,并计算胰岛素抵抗指数(HOMA-IR);HE染色进行肝脏组织病理学观察;RT-qPCR法检测肝脏FXR、SHP、PEPCK、ApoCⅡmRNA水平。结果:与模型组比较,茵陈五苓散高剂量组、茵陈五苓散低剂量组和辛伐他汀组体重、肝重和肝指数明显降低(P<0.05);FBG、FINS和HOMA-IR水平明显降低(P<0.05);血清TG、TC、LDL-C、AST、ALT含量明显降低,HDL-C含量升高(P<0.01);肝组织结构均有不同程度的改善(P<0.01);FXR、SHP、ApoCⅡmRNA表达增加(P<0.01),PEPCK mRNA表达减少(P<0.01)。结论:茵陈五苓散能够改善MAFLD大鼠糖脂代谢紊乱和肝脏组织病理状态,其机制可能与调节FXR/SHP/PEPCK和FXR/ApoCⅡ通路有关。

基于肠FXR-FGF15通路探讨沙棘熊果酸对酒精性肝损伤小鼠的影响

该研究借助小鼠酒精性肝损伤模型,观察沙棘熊果酸补充对酒精性肝损伤(alcoholic liver disease,ALD)小鼠的改善效果,通过分析沙棘熊果酸对ALD小鼠肠法尼醇X受体(farnesoid X receptor,FXR)-成纤维细胞生长因子15(fibroblast growth factor 15,FGF15)通路的影响,探讨其可能的保护作用机制。结果表明,沙棘熊果酸能够改善ALD小鼠的肝脏、小肠组织炎症反应,降低ALD小鼠血清谷草转氨酶(aspartate transaminase,AST)、谷丙转氨酶(glutamicpyruvic transaminase,ALT)活性、总胆汁酸(total bile acids,TBA)、脂多糖(lipopolysaccharide,LPS)、D-乳酸(D-lactic acid,D-LA)含量,提高ALD小鼠胆盐水解酶(bile salt hydrolase,BSH)浓度。同时,沙棘熊果酸可提高ALD小鼠肠道FXR、FGF15、肝脏中成纤维细胞生长因子受体第4号(fibroblast growth factor receptor 4,FGFR4)蛋白表达量,降低肝脏中胆固醇7α-羟化酶(cholesterol 7α-hydroxylase,CYP7A1)蛋白表达。综上,沙棘熊果酸对酒精性肝损伤小鼠具有保护作用,其机制可能与调节肠FXR-FGF15通路有关。

Reduction in Bile Acid Pool Causes Delayed Liver Regeneration Accompanied by Down-regulated Expression of FXR and C-Jun mRNA in Rats

The present study attempted to examine the effects of bile acid pool size on liver regeneration after hepatectomy.The rats were fed on 0.2% cholic acid(CA)or 2% cholestyramine for 7 days to induce a change in the bile acid size,and then a partial hepatectomy(PH)was performed.Rats fed on the normal diet served as the controls.Measurements were made on the rate of liver regeneration,the labeling indices of PCNA,the plasma total bile acids(TBA),and the mRNA expression of cholesterol 7alpha-hydroxylase(CYP7A1),...

Gut-liver axis signaling in portal hypertension

Portal hypertension(PHT)in advanced chronic liver disease(ACLD)results from increased intrahepatic resistance caused by pathologic changes of liver tissue composition(structural component)and intrahepatic vasoconstriction(functional component).PHT is an important driver of hepatic decompensation such as development of ascites or variceal bleeding.Dysbiosis and an impaired intestinal barrier in ACLD facilitate translocation of bacteria and pathogen-associated molecular patterns(PAMPs)that promote disease progression via immune system activation with subsequent induction of proinflammatory and profibrogenic pathways.Congestive portal venous blood flow represents a critical pathophysiological mechanism linking PHT to increased intestinal permeability:The intestinal barrier function is affected by impaired microcirculation,neoangiogenesis,and abnormal vascular and mucosal permeability.The close bidirectional relationship between the gut and the liver has been termed“gut-liver axis”.Treatment strategies targeting the gut-liver axis by modulation of microbiota composition and function,intestinal barrier integrity,as well as amelioration of liver fibrosis and PHT are supposed to exert beneficial effects.The activation of the farnesoid X receptor in the liver and the gut was associated with beneficial effects in animal experiments,however,further studies regarding efficacy and safety of pharmacological FXR modulation in patients with ACLD are needed.In this review,we summarize the clinical impact of PHT on the course of liver disease,discuss the underlying pathophysiological link of PHT to gut-liver axis signaling,and provide insight into molecular mechanisms that may represent novel therapeutic targets.

LXR及其靶基因COX-2和CETP在肥胖OSAHS幼鼠肝组织中的保护作用

目的阐明肝X受体(liver X receptor,LXR)及其靶基因环氧化酶-2(cyclooxygenase-2,COX-2)、胆固醇酯转移蛋白(cholesteryl ester transfer protein,CETP)的高表达是肥胖幼鼠阻塞性睡眠呼吸暂停综合征(obstructive sleep apnea-hypopnea syndrome,OSAHS)发病过程中的保护性因素,为肥胖儿童OSAHS的发病机制提供基础研究资料。方法24只3~4周龄雄性Wistar幼鼠分为正常对照组(control组)、单纯肥胖组(obesity组)、单纯OSAHS组(OSAHS组)、肥胖+OSAHS组(obesity+OSAHS组)。HE染色观察幼鼠肝组织病理变化;蛋白免疫印迹法(Western blotting)检测幼鼠肝组织中LXRα、COX-2、CETP的表达水平;运用免疫组化方法检测幼鼠肝组织中LXRα、COX-2、CETP的表达水平及分布情况。结果单纯肥胖组和肥胖+OSAHS组幼鼠体质量、总胆固醇(total cholesterol,TC)、甘油三酯(triglyceride,TG)含量与正常对照组相比均明显增加(P<0.05),单纯OSAHS组和肥胖+OSAHS组幼鼠血氧饱和度与正常对照组相比均明显降低(P<0.05)。单纯肥胖组、单纯OSAHS组及肥胖+OSAHS组肝组织与正常对照组肝组织相比均有明显损伤,肥胖+OSAHS组肝组织损伤较单纯肥胖组、单纯OSAHS组肝组织损伤程度明显升高。单纯OSAHS组和单纯肥胖组幼鼠肝组织中LXRα、COX-2、CETP表达水平较正常对照组均明显升高(P<0.05)。肥胖+OSAHS组幼鼠肝组织中LXRα、COX-2、CETP表达水平较其余各组均明显升高(P<0.05)。结论LXR及其靶基因COX-2、CETP在肥胖OSAHS幼鼠肝脏中高表达,是发病过程中的可能保护性因素。

附子理中汤通过FXR-FGF15通路影响非酒精性脂肪肝胆汁酸代谢

目的探讨附子理中汤对非酒精性脂肪性肝病(NAFLD)大鼠胆汁酸(TBA)代谢和肝脏损伤的影响及其机制。方法采用脂肪乳灌胃大鼠,连续4周,构建NAFLD动物模型。造模后用附子理中汤和阳性药物干预治疗,将大鼠分为对照组、模型组、附子理中汤组和阳性药物组。HE染色观察肝脏的病理变化,生化分析法检测高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)、游离脂肪酸(NEFA)的含量,Western blot检测回肠组织中法尼酯X受体(FXR)、成纤维细胞生长因子15(FGF15)的蛋白表达和肝脏组织中FXR的蛋白表达,RT-PCR检测回肠组织中FXR、FGF15的mRNA表达和肝脏组织中FXR的mRNA表达,ELISA检测肝组织TBA水平。结果与对照组比较,模型组大鼠肝脏出现严重病理损伤,血清中HDL-C含量下降,LDL-C和NEFA含量增加(均P<0.01),大鼠肝脏组织中FXR蛋白、mRNA表达和回肠组织中FXR、FGF15的蛋白、mRNA表达上升(均P<0.01),肝组织中TBA水平下降(P<0.01)。与模型组比较,附子理中汤组和阳性药物组大鼠肝脏病理损伤缓解,HDL-C含量增加,LDL-C和NEFA含量下降(均P<0.05),大鼠肝组织中FXR蛋白、mRNA表达和回肠组织中FXR、FGF15蛋白、mRNA表达下降(P<0.05),肝组织中TBA水平增加(P<0.01)。结论附子理中汤治疗可通过激活回肠FXR-FGF15信号,增加肝脏TBA代谢,缓解NAFLD引起的肝损伤。

法尼醇X受体在治疗胆汁淤积性肝病中的作用机制和药物研究进展

目的综述法尼醇X受体(FXR)在治疗胆汁淤积性肝病中的作用机制及以FXR为靶点的药物研究进展。方法对FXR通过调控胆汁酸的生成、代谢、转运以及肠肝循环等方式改善胆汁淤积的机制进行阐述,对FXR具有的抗炎、抗氧化和抗肝纤维化等作用和机制进行论述,对甾体和非甾体类FXR激动剂和FXR拮抗剂的治疗效果和临床试验进展进行综述。结果与结论胆汁淤积性肝病是以胆汁淤积为主要表现的一组临床常见疾病,其致病机制复杂,也一定程度上决定了用药的复杂性。核受体能调控胆汁酸体内平衡,是目前胆汁淤积治疗药物靶标的研究热点;FXR在保持胆汁酸平衡方面起着至关重要的作用,是一种生理性的胆汁酸核受体,被视为胆汁淤积和相关疾病的主要治疗靶点。随着对FXR研究的不断深入,发现其在胆汁酸稳态、抗炎、抗氧化、抗纤维化方面发挥核心调控作用,FXR激动剂和FXR拮抗剂不断被研发以治疗胆汁淤积性肝病。

肝X受体激动剂直接激活肝细胞NgBR的表达

Nogo-B受体(Nogo-B receptor,NgBR)参与脂肪肝和胰岛素敏感性的形成,但是并不清楚肝X受体(liver X receptor,LXR)激动剂是否能够调控NgBR的表达。文章使用人工合成的LXR激动剂(T0901317和GW3965)分析其对肝源细胞系中NgBR表达的影响,构建正常或突变NgBR启动子,通过双荧光素酶报告基因系统检测LXR激动剂对启动子活性的影响;采用CRISPR-CAS9方法建立LXRα或LXRβ基因敲除的HepG2细胞系,通过Western Blot检测相关基因的表达变化;向ApoE-/-小鼠腹腔注射LXR激动剂T0901317,分析小鼠肝脏中NgBR的表达变化。结果发现,LXR激动剂能够通过激活LXR促进NgBR蛋白的表达,该诱导作用是以LXRE依赖的方式进行的,并且LXR的表达发挥着重要作用。在体内实验中,也证明了LXR激动剂T0901317上调NgBR蛋白表达。结果表明,NgBR是LXR的靶蛋白,LXR通过结合NgBR启动子LXRE序列促进其转录和翻译。

FXR激动剂在非酒精性脂肪性肝炎治疗中的研究进展

非酒精性脂肪性肝炎(Non-alcoholic steatohepatitis,NASH),又称代谢性脂肪性肝炎,是病理变化与酒精性肝炎相似但无过量饮酒史的临床综合征,好发于中年特别是超重肥胖个体。非酒精性脂肪性肝炎与肥胖、胰岛素抵抗、2型糖尿病、高脂血症等代谢紊乱关系密切,主要特征为肝细胞大泡性脂肪变伴肝细胞损伤和炎症,严重者可发展为肝硬化,但至今NASH尚无得到批准的治疗方案。在寻找有效的治疗方法时,解决代谢失调、炎症和抗纤维化的新策略不断涌现。法尼类X受体(Farnesoid X receptor,FXR)除了是胆汁酸代谢和肠肝循环的关键调节剂外,还参与调节代谢稳态,使其成为NASH中有吸引力的治疗靶点。本文综述了FXR激动剂对NASH治疗的研究进展。