Regulation of PPAR-γ activity in lipid-laden hepatocytes affects macrophage polarization and inflammation in nonalcoholic fatty liver disease

BACKGROUNDLipid metabolism disorder and inflammatory-immune activation are vital triggers in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Various studies have shown that PPAR-γ exerts potent anti-inflammatory and immunomodulatory properties. However, little is known about the regulation of PPAR-γ activity in modulating cell crosstalk in NAFLD.AIMTo investigate whether the regulation of PPAR-γ activity in lipid-laden hepatocytes affects macrophage polarization and inflammation.METHODSPrimary hepatocytes were isolated from wild-type C57BL6/J mice or hepatocyte-specific PPAR-γ knockout mice and incubated with free fatty acids (FFAs). Macrophages were incubated with conditioned medium (CM) from lipid-laden hepatocytes with or without a PPAR-γ agonist. Wild-type C57BL/6J mice were fed a high-fat (HF) diet and administered rosiglitazone.RESULTSPrimary hepatocytes exhibited significant lipid deposition and increased ROS production after incubation with FFAs. CM from lipid-laden hepatocytes promoted macrophage polarization to the M1 type and activation of the TLR4/NF-κB pathway. A PPAR-γ agonist ameliorated oxidative stress and NLRP3 inflammasome activation in lipid-laden hepatocytes and subsequently prevented M1 macrophage polarization. Hepatocyte-specific PPAR-γ deficiency aggravated oxidative stress and NLRP3 inflammasome activation in lipid-laden hepatocytes, which further promoted M1 macrophage polarization. Rosiglitazone administration improved oxidative stress and NLRP3 inflammasome activation in HF diet-induced NAFLD mice in vivo.CONCLUSIONUpregulation of PPAR-γ activity in hepatocytes alleviated NAFLD by modulating the crosstalk between hepatocytes and macrophages via the reactive oxygen species-NLRP3-IL-1β pathway.     

Artemisia scoparia extract attenuates non-alcoholic fatty liver disease in diet-induced obesity mice by enhancing hepatic insulin and AMPK signaling independently of FGF21 pathway

Objective

Nonalcoholic fatty liver disease (NAFLD) is a common liver disease which has no standard treatment. In this regard, we sought to evaluate the effects of extracts of Artemisia santolinaefolia (SANT) and Artemisia scoparia (SCO) on hepatic lipid deposition and cellular signaling in a diet-induced obesity (DIO) animal model.

Materials/Methods

DIO C57/B6J mice were randomly divided into three groups, i.e. HFD, SANT and SCO. Both extracts were incorporated into HFD at a concentration of 0.5% (w/w). Fasting plasma glucose, insulin, adiponectin, and FGF21 concentrations were measured.

Results

At the end of the 4-week intervention, liver tissues were collected for analysis of insulin, AMPK, and FGF21 signaling. SANT and SCO supplementation significantly increased plasma adiponectin levels when compared with the HFD mice (P < 0.001). Fasting insulin levels were significantly lower in the SCO than HFD mice, but not in SANT group. Hepatic H&E staining showed fewer lipid droplets in the SCO group than in the other two groups. Cellular signaling data demonstrated that SCO significantly increased liver IRS-2 content, phosphorylation of IRS-1, IR β, Akt1 and Akt2, AMPK α1 and AMPK activity and significantly reduced PTP 1B abundance when compared with the HFD group. SCO also significantly decreased fatty acid synthase (FAS), HMG-CoA Reductase (HMGR), and Sterol regulatory element-binding protein 1c (SREBP1c), but not Carnitine palmitoyltransferase I (CPT-1) when compared with HFD group. Neither SANT nor SCO significantly altered plasma FGF21 concentrations and liver FGF21 signaling.

Conclusion

This study suggests that SCO may attenuate liver lipid accumulation in DIO mice. Contributing mechanisms were postulated to include promotion of adiponectin expression, inhibition of hepatic lipogenesis, and/or enhanced insulin and AMPK signaling independent of FGF21 pathway.     

miRNA-103: Molecular link between insulin resistance and nonalcoholic fatty liver disease

AIM: To investigate the associations between miRNA-103(mi R-103) and insulin resistance and nonalcoholic fatty liver disease(NAFLD).METHODS: Serum samples were collected from 50 NAFLD patients who were overweight or obese(NAFLD group) and from 30 healthy subjects who served as controls(normal control group). Quantitative polymerasechain reaction was used to detect expression of mi R-103. Fasting plasma glucose, fasting insulin, and triglyceride(TG) levels were measured. Homeostasis model assessment was used to evaluate basal insulin resistance(HOMA-IR). Patient height and weight were measured to calculate body mass index(BMI).RESULTS: Compared with the normal control group, higher serum levels of mi R-103 were expressed in the NAFLD group(8.18 ± 0.73 vs 4.23 ± 0.81, P = 0.000). When P = 0.01(bilateral), mi R-103 was positively correlated with HOMA-IR(r = 0.881), TG(r = 0.774) and BMI(r = 0.878), respectively. mi R-103, TG and BMI were all independent factors for HOMAIR(β = 0.438/0.657/0.251, P = 0.000/0.007/0.001). mi R-103, TG, BMI and HOMA-IR were all risk factors for NAFLD(odds ratio = 2.411/16.196/1.574/19.11, P = 0.009/0.022/0.01/0.014).CONCLUSION: mi R-103 is involved in insulin resistance and NAFLD, and may be a molecular link between insulin resistance and NAFLD and a therapeutic target for these disorders.     

Effects of probiotics on nonalcoholic fatty liver disease:A meta-analysis

AIM:To investigate the relationship between the gutliver axis and nonalcoholic fatty liver disease(NAFLD),we performed a meta-analysis to evaluate the effects of probiotic therapy in NAFLD.METHODS:We searched PubMed,Medline,Embase,Web of Science,the Cochrane Library and Chinese Biomedicine Database for all relevant randomized controlled trials on probiotics in patients with NAFLD/nonalcoholic steatohepatitis(NASH).A statistical analysis was performed using RevMan 5.0 software.RESULTS:Four randomized trials involving 134 NAFLD/NASH patients were included.The results showed that probiotic therapy signifcantly decreased alanine aminotransferase(ALT),aspartate transaminase(AST),total-cholesterol(T-chol),high density lipoprotein(HDL),tumor necrosis factor(TNF)-αand homeostasis model assessment of insulin resistance(HOMAIR)[ALT:weighted mean difference(WMD)-23.71,95%CI:-33.46--13.95,P<0.00001;AST:WMD-19.77,95%CI:-32.55--7.00,P=0.002;T-chol:WMD-0.28,95%CI:-0.55--0.01,P=0.04;HDL:WMD-0.09,95%CI:-0.16-0.01,P=0.03;TNF-α:WMD-0.32,95%CI:-0.48--0.17,P<0.0001;HOMA-IR:WMD-0.46,95%CI:-0.73--0.19,P=0.0008].However,the use of probiotics was not associated with changes in body mass index(BMI),glucose(GLU)and low density lipoprotein(LDL)(BMI:WMD 0.05,95%CI:-0.18-0.29,P=0.64;GLU:WMD 0.05,95%CI:-0.25-0.35,P=0.76;LDL:WMD-0.38,95%CI:-0.78-0.02,P=0.06).CONCLUSION:Probiotic therapies can reduce liver aminotransferases,total-cholesterol,TNF-αand improve insulin resistance in NAFLD patients.Modulation of the gut microbiota represents a new treatment for NAFLD.     

Plasma levels of asymmetric dimethylarginine in patients with biopsy-proven nonalcoholic fatty liver disease

Asymmetric (ADMA) and symmetric dimethylarginine (SDMA) are produced by breakdown of proteins that have been methylated posttranslationally at an arginine residue. Plasma levels of ADMA are elevated in insulin resistance states. Nonalcoholic fatty liver disease (NAFLD) is associated with insulin resistance and varying degrees of hepatic dysfunction. Because ADMA is metabolized in the liver, we hypothesized that ADMA levels will be high in patients with NAFLD as a consequence of hepatic dysfunction and insulin resistance. Plasma levels of ADMA, SDMA, total homocysteine, glucose, and insulin were measured in nondiabetic patients with biopsy-proven NAFLD (11 steatosis and 24 nonalcoholic steatohepatitis) and 25 healthy subjects. Plasma ADMA levels were significantly higher (P = .029) in patients with biopsy-proven NAFLD (0.43 ± 0.21 μmol/L) compared with controls (0.34 ± 0.10 μmol/L). However, when adjusted for insulin resistance (homeostasis model assessment), the difference between 2 groups was not evident. Plasma SDMA levels were similar in all 3 groups. Plasma levels of ADMA were positively correlated with plasma total homocysteine levels (P = .003). Plasma levels of SDMA were negatively correlated with estimated glomerular filtration rate (P = .016) and positively correlated with plasma total homocysteine levels (P = .003). The ratio of ADMA/SDMA was positively correlated with body mass index (P = .027). Elevated plasma concentrations of ADMA in biopsy-proven NAFLD were primarily related to insulin resistance. Hepatic dysfunction in NAFLD does not appear to make significant contribution to changes in plasma methylarginine levels.     

Dual probiotic strains suppress high fructose-induced metabolic syndrome

AIM:To investigate the effect of novel probiotics on the clinical characteristics of high-fructose induced metabolic syndrome.METHODS:Male Wistar rats aged 4 wk were fed a 70% w/w high-fructose diet(n = 27) or chow diet(n = 9) for 3 wk to induce metabolic syndrome,the rats were then randomized into groups and administered probiotic [Lactobacillus curvatus(L.curvatus) HY7601 and Lactobacillus plantarum(L.plantarum) KY1032] at 109 cfu/d or 1010 cfu/d or placebo by oral gavage for 3 wk.Food intake and body weight were measured once a week.After 6 wk,the rats were fasted for 12 h,then anesthetized with diethyl ether and sacrificed.Blood samples were taken from the inferior vena cava for plasma analysis of glucose,insulin,C-peptide,totalcholesterol,triglycerides and thiobarbituric acid-reacting substances.Real-time polymerase chain reaction was performed using mouse-specific Taqman probe sets to assess genes related to fatty acid β-oxidation,lipogenesis and cholesterol metabolism in the liver.Target gene expression was normalized to the housekeeping gene,glyceraldehyde-3-phosphate dehydrogenase.RESULTS:Rodents fed a high-fructose diet developed clinical characteristics of the metabolic syndrome including increased plasma glucose,insulin,triglycerides,total cholesterol and oxidative stress levels,as well as increased liver mass and liver lipids compared to chow fed controls.Probiotic treatment(L.curvatus HY7601 and L.plantarum KY1032) at high(1010 cfu/d) or low dosage(109 cfu/d) lowered plasma glucose,insulin,triglycerides and oxidative stress levels.Only high-dose probiotic treatment reduced liver mass and liver cholesterol.Probiotic treatment reduced lipogenesis via downregulation of SREBP1,FAS and SCD1 mRNA levels and increased β-oxidation via up-regulation of PPARα and CPT2 mRNA levels.CONCLUSION:Probiotic L.curvatus HY7601 and L.plantarum KY1032 combined suppressed the clinical characteristics of high-fructose-induced metabolic syndrome,therefore,may provide a natural alternative for the treatment of diet-indu     

Increased circulating zonulin in children with biopsy-proven nonalcoholic fatty liver disease

AIM:To investigate the potential association of circulating zonulin with the stage of liver disease in obese children with biopsy-confirmed nonalcoholic fatty liver disease(NAFLD).METHODS:A case-control study was performed.Cases were 40 obese children with NAFLD.The diagnosis of NAFLD was based on magnetic resonance imaging(MRI)with high hepatic fat fraction(HFF≥5%),and confirmed by liver biopsy with≥5%of hepatocytes containing macrovesicular fat.Controls were selected from obese children with normal levels of aminotransferases,and without MRI evidence of fatty liver as well as of other causes of chronic liver diseases.Controls were matched(1-to 1)with the cases on age,gender,pubertal stage and as closely as possible on body mass index-standard deviation score.All participants underwent clinical examination,laboratory testsincluding zonulin,inflammatory and metabolic parameters,and MRI for measurement of HFF and visceral adipose tissue.RESULTS:Zonulin values were significantly greater in obese subjects with NAFLD than in those without NAFLD[median(interquartile range),4.23(3.18-5.89)vs 3.31(2.05-4.63),P<0.01].In patients with NAFLD,zonulin concentrations increased significantly with the severity of steatosis and the Spearman’s coefficient revealed a positive correlation between zonulin values and steatosis(r=0.372,P<0.05);however,we did not find a significant correlation between zonulin and lobular inflammation(P=0.23),ballooning(P=0.10),fibrosis score(P=0.18),or presence of nonalcoholic steatohepatitis(P=0.17).Within the entire study population,zonulin levels were positively associated with gamma-glutamyl transferase,2-h insulin,HFF,and negatively associated with whole-body insulin sensitivity index(WBISI),after adjustment for age,gender and pubertal status.When the associations were restricted to the group of NAFLD patients,2-h insulin,hepatic fat,and WBISI retained statistical significance.CONCLUSION:Circulating zonulin is increased in children and adolescents with NAFLD and correlates with the severity of steatosis.     

非酒精性脂肪性肝病小鼠肝组织与脂质代谢相关基因FAS、ACC和SREBP-1水平分析*

目的 探讨非酒精性脂肪性肝病(NAFLD)小鼠肝组织脂质代谢相关基因水平变化。方法 采用高脂饲料喂养20小鼠,构建小鼠NAFLD动物模型,观察小鼠肝组织病理学变化,检测血清总胆固醇(TCH) 和甘油三酯(TG)含量,采用RT-PCR法检测小鼠肝组织胆固醇调节元件结合蛋白(SREBPs)、乙酰辅酶A羧化酶(ACC)和脂肪酸合成酶(fatty acid synthase, FAS)基因变化。结果 10只NAFLD模型小鼠肝细胞排列不整齐,肝细胞内出现大小不等的脂滴;NAFLD模型小鼠血清TG和TCH水平分别为(0.63±0.13)mmol/L和(7.23±0.7)mmol/L,显著高于10只对照组[(0.28±0.06)mmol/L和(2.78±0.6)mmol/L,P<0.001];在实验24 w末,NAFLD组小鼠肝组织FAS 和SREBP-1 mRNA水平分别为(3.9±1.1)和(1.8±0.7),对照组则分别为【(1.0±0.3)和(1.0±0.4),FAS: t = 6.231, P<0.001; SREBP-1: t =2.431, P =0.035】,差异显著,而NAFLD组小鼠肝组织ACC mRNA水平为(1.2±0.5),与对照组【(1.0±0.4), t=0.765, P=0.462】比,无显著差异。结论 NAFLD模型小鼠肝组织与脂质代谢相关基因显著上调,为进一步研究NAFLD的发生发展机制奠定了基础。     

Ezetimibe decreases SREBP-1c expression in liver and reverses hepatic insulin resistance in mice fed a high-fat diet

Ezetimibe inhibits intestinal cholesterol absorption, thereby reducing serum cholesterol. Recent studies suggest that ezetimibe affects liver steatosis and insulin resistance. We investigated the impact of ezetimibe on insulin sensitivity and glucose metabolism in C57BL/6 mice. We analyzed 4 mouse groups fed the following diets: normal chow (4% fat) for 12 weeks, normal chow for 10 weeks followed by normal chow plus ezetimibe for 2 weeks, high-fat chow (32% fat) for 12 weeks, and high-fat chow for 10 weeks followed by high-fat chow plus ezetimibe for 2 weeks. In the normal chow + ezetimibe group, ezetimibe had no impact on body weight, fat mass, lipid metabolism, liver steatosis, glucose tolerance, or insulin sensitivity. In the high-fat chow + ezetimibe group, ezetimibe had no impact on body weight or fat mass but significantly decreased serum low-density lipoprotein cholesterol, triglyceride, and glutamate pyruvate transaminase levels; liver weight; hepatic triglyceride content; and hepatic cholesterol content and increased the hepatic total bile acid content. In association with increases in IRS-2 and Akt phosphorylation, ezetimibe ameliorated hepatic insulin resistance in the high-fat chow + ezetimibe group, but had no effect on insulin sensitivity in primary cultured hepatocytes. A DNA microarray and Taqman polymerase chain reaction revealed that ezetimibe up-regulated hepatic SREBP2 and SHP expression and down-regulated hepatic SREBP-1c expression. SHP silencing mainly in the liver worsened insulin resistance, and ezetimibe protected against insulin resistance induced by down-regulation of SHP. Ezetimibe down-regulated SREBP-1c in the liver and reversed hepatic insulin resistance in mice fed a high-fat diet.     

对氧磷酶-1参与调控非酒精性脂肪肝脂质代谢与胰岛素抵抗作用及机制

目的探究对氧磷酶-1(Paraoxonase 1,PON1)与非酒精性脂肪肝(Nonalcoholic fatty liver disease,NAFLD)脂质代谢与胰岛素抵抗关系及机制。方法选取129例NAFLD患者和130非NAFLD患者为研究对象,收集患者年龄、身高、体重、腰围,血压等信息,检测血脂、空腹血糖(Fast Glucose)、胰高血糖素(Glucagon)、胰岛素(Fast Insulin)、评估胰岛素抵抗的稳态指数(homeostatic index of insulin resistance,HOMA-IR)、肝肾功能、脂肪因子等,LO2细胞接种12孔板培养24 h后分别加入0~1.2 mmol OA溶液处理24 h或10 ng/mL TNF-α处理6 h,以PEI转染空载质粒和PON1质粒1μg 24 h。使用尼罗红染料测定细胞内脂质含量。ELISA法检测PON1活性,蛋白质印迹检测PON1、p-IRS1、T-IRS1、p-AKT T-AKT、FAS、HMGCR、SREBP2和SREBP1C蛋白表达。结果NAFLD患者腰围、BMI、外周血ALT、AST、FFA、TG、TC、LDL-C、VLDL-C、空腹血糖、胰岛素、HOMA-IR、抵抗素、瘦素、IL-6和TNF-α显著高于非NAFLD,PON1活性、含量、HDL-C、胰高血糖素和脂联素显著降低;血PON1活性和含量与FFAs、TG、TC、LDL-C、VLDL-C、空腹血糖、胰岛素、HOMA-IR、抵抗素、瘦素、IL-6和TNF-α显著负相关,与HDL-C、胰高血糖素和脂联素显著正相关;OA组LO2细胞PON1的活性逐渐降低,且0.2~1.2 mM OA组LO2细胞PON1的活性显著低于Control组,过表达PON1不影响PON1活性,0.2~1.2 mM OA组LO2细胞内脂质含量显著高于Control组,显著低于OA组;TNF-α组LO2细胞PON1、p-IRS1、p-AKT、FAS、HMGCR、SREBP2和SREBP1C蛋白表达量相比于Control组显著降低,转染PON1质粒显著增加PON1,同时p-IRS1、p-AKT、FAS、HMGCR、SREBP2和SREBP1C蛋白表达量显著增加。结论PON1活性与含量和NAFLD血脂代谢及胰岛素抵抗显著相关,且可能通过调控p-IRS1/AKT通路影响胰岛素抵抗,并调控脂质代谢。     

Vitamin E reduces liver stiffness in nonalcoholic fatty liver disease

AIM: To evaluate the efficacy of vitamin E treatment on liver stiffness in nonalcoholic fatty liver disease(NAFLD).METHODS: Thirty-eight NAFLD patients were administered vitamin E for 1 year. The doses of vitamin E were 150, 300, or 600 mg; three times per day after each meal. Responses were assessed by liver enzyme levels [aspartate aminotransferase(AST), alanine aminotranferease(ALT), and γ-glutamyl transpeptidase(γ-GTP)], noninvasive scoring systems of hepatic fibrosis-4 [FIB-4 index and aspartate aminotransferaseto-platelet index(APRI)], and liver stiffness [velocity of shear wave(Vs)] measured by acoustic radiation force impulse elastography. Vs measurements were performed at baseline and 12 mo after baseline. The patients were genotyped for the patatin-like phospholipase domain containing 3(PNPLA3) polymorphisms and then divided into either the CC/CG or GG group to examine each group's responses to vitamin E treatment. RESULTS: We found marked differences in the platelet count, serum albumin levels, alkaline phosphatase levels, FIB-4 index, APRI, and Vs at baseline depending on the PNPLA3 polymorphism. AST, ALT, and γ-GTP levels(all P 0.001); FIB-4 index(P = 0.035); APRI(P 0.001); and Vs(P 0.001) significantly decreased from baseline to 12 mo in the analysis of all patients. In the subset analyses of PNPLA3 genotypes, AST levels(P = 0.011), ALT levels(P 0.001), γ-GTP levels(P = 0.005), APRI(P = 0.036), and Vs(P = 0.029) in genotype GG patients significantly improved, and AST and ALT levels(both P 0.001), γ-GTP levels(P = 0.003), FIB-4 index(P = 0.017), and APRI(P 0.001) in genotype CC/CG patients. CONCLUSION: One year of vitamin E treatment improved noninvasive fibrosis scores and liver stiffness in NAFLD patients. The responses were similar between different PNPLA3 genotypes.     

Effects of pentoxifylline on nonalcoholic fatty liver disease: A meta-analysis

AIM:To evaluate the effects of pentoxifylline therapy in patients with nonalcoholic fatty liver disease(NAFLD).METHODS:We searched PubMed,Medline,Google Scholar,Embase,Web of Science,the Cochrane Library and the Chinese Biomedicine Database for all relevant controlled trials of pentoxifylline in patients with NAFLD from 1997 to July 2013.Five studies(3 randomized,double-blind,placebo-controlled trials and 2 prospective cohort studies with concurrent controls)were included in this meta-analysis.Statistical analysis was performed using RevMan 5.0 software.RESULTS:Five randomized trials of 147 patients with NAFLD/nonalcoholic steatohepatitis(NASH)were included.The results showed that compared to placebo,pentoxifylline therapy resulted in a signi?cant decrease in body weight(P=0.04),alanine aminotransferase (P<0.00001),aspartate transaminase(P=0.0006),glucose(P=0.0008)and tumor necrosis factor-α(P=0.007),but did not significantly affect body mass index(P=0.28),total cholesterol(P=0.80),triglyceride(P=0.98),alkaline phosphatase(P=0.29),γ-glutamyl transferase(P=0.39)and interleukin-6(P=0.38).With regard to histological changes,pentoxifylline only reduced the NAFLD activity score(P<0.00001)and improved lobular inflammation(P<0.0001).Improvements in steatosis grade(P=0.11),ballooning(P=0.10)and fibrosis(P=0.50)were not obvious.CONCLUSION:Pentoxifylline therapy results in weight loss,improved liver function and histological changes in patients with NAFLD/NASH.Therefore,pentoxifylline may be a new treatment option for NAFLD.     

Insulin resistance and NAFLD: Relationship with intrahepatic iron and serum TNF-α using 1H MR spectroscopy and MRI

AimThe association of non-alcoholic fatty liver disease (NAFLD) with insulin resistance (IR) is well established, yet little is known of their possible relationship with intrahepatic iron and serum tumour necrosis factor (TNF)-α concentrations in adults without diabetes. Thus, this study looked at the relationship of intrahepatic iron and serum TNF-α with intrahepatic triglycerides and IR in non-diabetic adults.MethodsIn this cross-sectional study of 104 healthy non-diabetic Caucasians, a quantitative magnetic resonance (MR) imaging T2 gradient-echo technique was used to measure hepatic iron, with 1H-MR spectroscopy used to measure hepatic triglycerides. HOMA-IR was calculated to determine IR.ResultsThe prevalence of hepatic iron overload (HIOL) was 26.6% in individuals with NAFLD vs. 0% in those without. IR was present in 87.5% of subjects with both NAFLD and HIOL, in 45.4% of those with NAFLD but not HIOL, and in 4.5% of those with neither. HOMA-IR was positively correlated with hepatic triglycerides (r = 0.56, P < 0.001) and hepatic iron (r = 0.52, P < 0.001), whereas serum TNF-α concentrations correlated with intrahepatic triglyceride levels (r = 0.28, P < 0.04), but not with intrahepatic iron. Hepatic triglycerides, serum TNF-α and age were the only significant determinants of IR in regression analyses.ConclusionIR is closely associated with intrahepatic triglycerides and, to a lesser extent, intrahepatic iron, with some interplay between them. High serum TNF-α concentrations may contribute to the association between NAFLD and IR, while increased hepatic triglycerides appear to be a determinant of the development of HIOL in non-diabetic subjects without haemochromatosis.     

Mitofusin-2 ameliorates high-fat diet-induced insulin resistance in liver of rats

AIM:To investigate the effects of mitofusin-2(MFN2) on insulin sensitivity and its potential targets in the liver of rats fed with a high-fat diet(HFD).METHODS:Rats were fed with a control or HFD for 4 or 8 wk,and were then infected with a control or an MFN2 expressing adenovirus once a week for 3wk starting from the 9th wk.Blood glucose(BG),plasma insulin and insulin sensitivity of rats were determined at end of the 4th and 8th wk,and after treatment with different amounts of MFN2 expressing adenovirus(108,109 or 1010 vp/kg body weight).BG levels were measured by Accu-chek Active Meter.Plasma insulin levels were analyzed by using a Rat insulin enzymelinked immunosorbent assay kit.Insulin resistance was evaluated by measuring the glucose infusion rate(GIR) using a hyperinsulinemic euglycemic clamp technique.The expression or phosphorylation levels of MFN2 and essential molecules in the insulin signaling pathway,such as insulin receptor(INSR),insulin receptor substrate 2(IRS2),phosphoinositide-3-kinase(PI3K),protein kinase beta(AKT2) and glucose transporter type 2(GLUT2) was assayed by quantitative real-time polymerase chain reaction and Western-blotting.RESULTS:After the end of 8wk,the body weight of rats receiving the normal control diet(ND) and the HFD was not significantly different(P>0.05).Compared with the ND group,GIR in the HFD group was significantly decreased(P<0.01),while the levels of BG,triglycerides(TG),total cholesterol(TC) and insulin in the HFD group were significantly higher than those in the ND group(P<0.05).Expression of MFN2 mRNA and protein in liver of rats was significantly downregulated in the HFD group(P<0.01) after 8 wk of HFD feeding.The expression of INSR,IRS2 and GLUT2 were down-regulated markedly(P<0.01).Although there were no changes in PI3K-P85 and AKT2 expression,their phosphorylation levels were decreased significantly(P<0.01).After intervention with MFN2 expressing adenovirus for 3wk,the expression of MFN2 mRNA and protein levels were up-regulated(P<0.01).Th     

Adipokines and C-reactive protein in relation to bone mineralization in pediatric nonalcoholic fatty liver disease

AIM: To investigate bone mineral density (BMD) in obese children with and without nonalcoholic fatty liver disease (NAFLD); and the association between BMD and serum adipokines, and high-sensitivity C-reactive protein (HSCRP). METHODS: A case-control study was performed. Cases were 44 obese children with NAFLD. The diagnosis of NAFLD was based on magnetic resonance imaging (MRI) with high hepatic fat fraction (≥ 5%). Other causes of chronic liver disease were ruled out. Controls were selected from obese children with normal levels of aminotransferases, and without MRI evidence of fatty liver as well as of other causes of chronic liver diseases. Controls were matched (1-to 1-basis) with thecases on age, gender, pubertal stage and as closely as possible on body mass index-SD score. All participants underwent clinical examination, laboratory tests, and whole body (WB) and lumbar spine (LS) BMD by dual energy X-ray absorptiometry. BMDZ-scores were calcu- lated using race and gender specific LMS curves. RESULTS: Obese children with NAFLD had a significantly lower LS BMDZ-score than those without NAFLD [mean, 0.55 (95%CI: 0.23-0.86) vs 1.29 (95%CI: 0.95-1.63); P < 0.01]. WB BMD Z-score was also decreased in obese children with NAFLD compared to obese children with no NAFLD, though borderline significance was observed [1.55 (95%CI: 1.23-1.87) vs 1.95 (95%CI: 1.67-2.10); P = 0.06]. Children with NAFLD had significantly higher HSCRP, lower adiponectin, but similar leptin levels. Thirty five of the 44 children with MRI-diagnosed NAFLD underwent liver biopsy. Among the children with biopsy-proven NAFLD, 20 (57%) had nonalcoholic steatohepatitis (NASH), while 15 (43%) no NASH. Compared to children without NASH, those with NASH had a significantly lower LS BMD Z-score [mean, 0.27 (95%CI: -0.17-0.71) vs 0.75 (95%CI: 0.13-1.39); P < 0.05] as well as a significantly lower WB BMD Z-score [1.38 (95%CI: 0.89-1.17) vs 1.93 (95%CI: 1.32-2.36); P < 0.05]. In multiple regression analysis, NASH (standardized β coefficient,     

Down-regulation of hepatic stearoyl-CoA desaturase 1 expression by angiotensin II receptor blocker in the obese fa/fa Zucker rat: possible role in amelioration of insulin resistance and hepatic steatosis

Background  It has been reported that angiotensin II type 1 receptor blocker (ARB) can ameliorate hepatic steatosis and insulin resistance. Stearoyl-CoA desaturase 1 (SCD-1), which catalyzes the cellular synthesis of monounsaturated fatty acids, affects lipid metabolism. In this study, we investigated whether SCD-1 gene expression is affected by ARB treatment. Methods  Obese fa/fa Zucker rats fed a high-fat diet were treated with a potent ARB and olmesartan, and the resulting changes in the components of serum and liver were studied. Gene expression of hepatic SCD-1 was assayed using real-time PCR. Results  The serum glucose and insulin levels and hepatic TG content of the obese Zucker rats fed a high-fat diet were reduced after olmesartan administration, while the serum adiponectin level was increased. Real-time PCR revealed an increase of SCD-1 gene expression in the liver of these rats, followed by a reduction after olmesartan administration. The ratio of stearic acid (C18:0) to oleic acid (C18:1) in the liver was increased by olmesartan, indicating a reduction in the in vivo activity of SCD-1. Conclusions  ARB ameliorates hepatic steatosis and insulin resistance in obese fa/fa Zucker rats fed a high-fat diet. Gene expression of SCD-1 is decreased by olmesartan, suggesting that the beneficial effect is due partly to suppression of the key enzyme for hepatic lipid metabolism by ARB.