Association between Serum Growth Hormone Levels and Nonalcoholic Fatty Liver Disease: A Cross-Sectional Study

Growth hormone (GH) is an important regulator of metabolism and body composition. GH deficiency is associated with increased visceral body fat and other features of the metabolic syndrome. Here we performed a cross-sectional study to explore the association of GH levels with nonalcoholic fatty liver disease (NAFLD), which is considered to be the hepatic manifestation of the metabolic syndrome. A total of 1,667 subjects were diagnosed as NAFLD according the diagnostic criteria, and 5,479 subjects were defined as the controls. The subjects with NAFLD had significantly lower levels of serum GH than the controls. Those with low GH levels had a higher prevalence of NAFLD and the metabolic syndrome. A stepwise logistic regression analysis showed that GH levels were significantly associated with the risk factor for NAFLD (OR = 0.651, 95%CI = 0.574–0.738, P<0.001). Our results showed a significant association between lower serum GH levels and NAFLD.     

Correlates and Heritability of Nonalcoholic Fatty Liver Disease in a Minority Cohort

Nonalcoholic fatty liver disease (NAFLD) is associated with obesity and insulin resistance. The condition disproportionately affects Hispanic Americans. The aims of this study were to examine the risk factors and heritability of NAFLD in 795 Hispanic American and 347 African‐American adults participating in the Insulin Resistance Atherosclerosis Study (IRAS) Family Study. Computed tomography (CT) scans of the abdomen were evaluated centrally for measures of liver–spleen (LS) density ratio and abdominal fat distribution. Other measures included insulin sensitivity (S_I) calculated from a frequently sampled intravenous glucose tolerance test and various laboratory measures. Statistical models which adjust for familial relationships were estimated separately for the two ethnic groups. Heritability was calculated using a variance components approach. The mean age of the cohort was 49 years (range 22–84); 66% were female. NAFLD (LS ratio <1) was more common in Hispanic Americans (24%) than African Americans (10%). NAFLD was independently associated with S_I and visceral adipose tissue (VAT) area in both ethnic groups, although the proportion of explained variance was considerably higher in the Hispanic models. Adiponectin contributed significantly in the African‐American models whereas triglycerides (TGs) and plasminogen activator inhibitor 1 (PAI‐1) contributed only in the Hispanic models. Liver density was modestly heritable in both ethnic groups (h² ～0.35). In summary, the prevalence of NAFLD was twofold greater in Hispanic than African Americans. Certain correlates of NAFLD were similar between the ethnic groups, whereas others were distinct. NAFLD was modestly heritable. These findings suggest that NAFLD may have a differing environmental and/or genetic basis in these ethnic groups.     

Nonalcoholic Fatty Liver Disease and Risk of Diabetes: A Prospective Study in China

Objective: We aimed to investigate whether liver steatosis severity affects the risk of developing diabetes in a large cohort study.Methods: We prospectively examined the association in 41,650 Chinese adults with negative hepatitis-B surface antigen who were free of alcohol consumption, diabetes, and liver cirrhosis at baseline. Cox proportional models were used to estimate the risk of diabetes after a mean of 3.6 years of follow-up. Nonalcoholic fatty liver disease (NAFLD) was assessed with hepatic ultrasonography. Elevated alanine transaminase (ALT) was defined as ALT concentrations >19 and >30 U/L in females and males, respectively. Diabetes was defined as a fasting glucose ³7.0 mmol/L or treatment with hypoglycemic medication.Results: Liver steatosis severity was significantly associated with higher risks of developing diabetes (adjusted hazard ratio [HR] for severe vs. without NAFLD = 2.66, 95% confidence interval [CI]: 2.17–3.25, P-trend<.001) and impaired fasting glucose (fasting glucose between 5.6 and 6.9 mmol/L, adjusted HR = 1.36, 95% CI: 1.16–1.59, P-trend<.001), as well as a faster increase rate of fasting glucose concentrations (P-trend<.001), during 3.6 years of follow-up. Elevated ALT was also associated with incident diabetes (HR = 1.12, 95% CI: 1.02–1.22), adjusting for NAFLD and other covariates.Conclusion: We observed a dose-response relationship between liver steatosis severity and increased diabetes risk, and ALT may predict incident diabetes independently of NAFLD.Abbreviations: ALT = alanine transaminase; BP = blood pressure; CI = confidence interval; HCV = hepatitis C virus; HR = hazard ratio; IFG = impaired fasting glucose; NAFLD = nonalcoholic fatty liver disease; ULN = upper limit of normal     

非酒精性脂肪性肝病与代谢综合征组分的相关性研究进展

非酒精性脂肪性肝病(nonalcoholic fatty liver disease,NAFLD)在全世界人群中发病率逐年上升,成为新的全球公共健康问题,已越来越引起临床关注。其发病以胰岛素抵抗为基础,与肥胖、血脂紊乱、原发性高血压、2型糖尿病等代谢综合征各组分密切相关。NAFLD可进展至肝硬化、肝衰竭甚至肝癌,伴有代谢综合征一种或多种组分可能加速疾病的进展。NAFLD初期是一种可逆性过程,充分了解影响其发生、发展的相关代谢危险因素并及时纠正,可能导致疾病的逆转或延缓其进程。本文就NAFLD与代谢综合征各组分的相关调查研究进行综述。     

Diabetes of the Liver: The Link Between Nonalcoholic Fatty Liver Disease and HFCS‐55

Nonalcoholic fatty liver disease (NAFLD) is associated with obesity and insulin resistance. It is also a predisposing factor for type 2 diabetes. Dietary factors are believed to contribute to all three diseases. NAFLD is characterized by increased intrahepatic fat and mitochondrial dysfunction, and its etiology may be attributed to excessive fructose intake. Consumption of high fructose corn syrup‐55 (HFCS‐55) stands at up to 15% of the average total daily energy intake in the United States, and is linked to weight gain and obesity. The aim of this study was to establish whether HFCS‐55 could contribute to the pathogenesis of NAFLD, by examining the effects of HFCS‐55 on hepatocyte lipogenesis, insulin signaling, and cellular function, in vitro and in vivo. Exposure of hepatocytes to HFCS‐55 caused a significant increase in hepatocellular triglyceride (TG) and lipogenic proteins. Basal production of reactive oxygen metabolite (ROM) was increased, together with a decreased capacity to respond to an oxidative challenge. HFCS‐55 induced a downregulation of the insulin signaling pathway, as indicated by attenuated ^ser473phosphorylation of AKT1. The c‐Jun amino‐terminal kinase (JNK), which is intimately linked to insulin resistance, was also activated; and this was accompanied by an increase in endoplasmic reticulum (ER) stress and intracellular free calcium perturbation. Hepatocytes exposed to HFCS‐55 exhibited mitochondrial dysfunction and released cytochrome C (CytC) into the cytosol. Hepatic steatosis and mitochondrial disruption was induced in vivo by a diet enriched with 20% HFCS 55; accompanied by hypoadiponectinemia and elevated fasting serum insulin and retinol‐binding protein‐4 (RBP4) levels. Taken together our findings indicate a potential mechanism by which HFCS‐55 may contribute to the pathogenesis of NAFLD.     

Genetics of Nonalcoholic Fatty Liver Disease:An Overview

Nonalcoholic fatty liver disease(NAFLD) is the most common liver disease in the world today.Its incidence in adults and children is rising rapidly due to the ongoing epidemics of obesity and type 2 diabetes.Hence,it has become a global public health issue.Environmental factors have been found to play a major role in the etiology of NAFLD,especially for genetically susceptible populations. Among these,one of the most important factors is junk food,especially the typical "Western-style" diet rich in simple carbohydrates, saturated fat,and highly processed food materials.Genetic predisposition to NAFLD does occur;however,a precise definition of genetic factors responsible for NAFLD is still lacking.Specific variants of different genes have been shown to present a risk for NAFLD.Genetic studies might be helpful in the management of the disease by developing novel treatment strategies based on individual’s genotype.     

Prediction of Metabolic Syndrome by Non-Alcoholic Fatty Liver Disease in Northern Urban Han Chinese Population: A Prospective Cohort Study

Objectives

To explore the relationship between non-alcoholic fatty liver disease (NAFLD) and the metabolic syndrome (MetS), and evaluate the value of NAFLD as a marker for predicting the risk of MetS in a large scale prospective cohort from northern urban Han Chinese population.

Materials and Methods

A total of 17,920 MetS-free at baseline cohort members was included in the current study between 2005 and 2011. The baseline characteristics of the cohort were compared by NAFLD status at baseline, MetS status after follow-up. Cox proportional hazards models were used to estimate the unadjusted or adjusted hazard ratios (HRs) for NAFLD at baseline predicting the risk of MetS.

Results

2,183 (12.18%) new cases of MetS occurred between 2005 and 2011. In unadjusted model, HRs (95% CIs) for NAFLD predicting MetS was 3.65 (3.35, 3.97). After adjusting the confounding factors of age, gender, the metabolic factors, smoke and exercise, the HRs (95% CIs) was 1.70 (1.55, 1.87). Gender difference was observed, adjusted HRs (95% CIs) of NAFLD for predicting MetS were 2.06(1.72, 2.46) and 1.55(1.39, 1.72) in female and male population, respectively. Moreover, 163 participants developed MetS among participants without any MetS component at baseline, and its adjusted HRs was still significant, 1.87 (1.12, 3.13).

Conclusion

The present study indicates that NAFLD is an independent risk factor for predicting the risk of MetS in northern urban Han Chinese population, and the people with NAFLD should initiate weight and dietary control to prevent the occurrence of MetS.     

Association Between Non-Alcoholic Fatty Liver Disease and Diabetes-Related Microvascular Complications: A Retrospective Cross-Sectional Study of Hospitalized Patients

ObjectiveOwing to limited research, the effect of nonalcoholic fatty liver disease (NAFLD) on type 2 diabetes outcomes remains unclear. This study aimed to investigate the association between NAFLD and microvascular complications in hospitalized patients with type 2 diabetes.MethodsWe included 1982 patients with type 2 diabetes. NAFLD was defined as hepatic steatosis detected by ultrasound without secondary causes of fat accumulation. The diagnosis of diabetic retinopathy (DR), diabetic kidney disease (DKD), and diabetic neuropathy was based on clinical medical records. Risk for advanced liver fibrosis was categorized as “low risk,” “indeterminate risk,” and “high risk,” based on the NAFLD fibrosis score (NAFLD-FS). Logistic regression was used to test the association between NAFLD, risk for advanced fibrosis, and the presence of DR, DKD, and diabetic neuropathy.ResultsThe prevalence of NAFLD was 61.3%. The presence of DR and DKD was inversely associated with NAFLD, after adjusting for covariates. The presence of DR and DKD was higher in the “indeterminate risk” and “high risk” groups than in the “low risk” group, after adjusting for the same covariates. Only the presence of DKD significantly increased with high NAFLD-FS.ConclusionThe presence of DR and DKD was inversely associated with NAFLD among hospitalized patients with type 2 diabetes. DKD was closely associated with high NAFLD-FS among patients with NAFLD.     

Diet-Quality Scores and Prevalence of Nonalcoholic Fatty Liver Disease: A Population Study Using Proton-Magnetic Resonance Spectroscopy

Dietary pattern analysis is an alternative approach to examine the association between diet and nonalcoholic fatty liver disease (NAFLD). This study examined the association of two diet-quality scores, namely Diet Quality Index-International (DQI-I) and Mediterranean Diet Score (MDS) with NAFLD prevalence. Apparently healthy Chinese adults (332 male, 465 female) aged 18 years or above were recruited through a population screening between 2008 and 2010 in a cross-sectional population-based study in Hong Kong. DQI-I and MDS, as well as major food group and nutrient intakes were calculated based on dietary data from a food frequency questionnaire. NAFLD was defined as intrahepatic triglyceride content at ≥5% by proton-magnetic resonance spectroscopy. Multivariate logistic regression models were used to examine the association between each diet-quality score or dietary component and prevalent NAFLD with adjustment for potential lifestyle, metabolic and genetic factors. A total of 220 subjects (27.6%) were diagnosed with NAFLD. DQI-I but not MDS was associated with the prevalence of NAFLD. A 10-unit decrease in DQI-I was associated with 24% increase in the likelihood of having NAFLD in the age and sex adjusted model (95% CI: 1.06–1.45, p = 0.009), and the association remained significant when the model was further adjusted for other lifestyle factors, metabolic and genetic factors [OR: 1.26 (95% CI: 1.03–1.54), p = 0.027]. Multivariate regression analyses showed an inverse association of the intake of vegetables and legumes, fruits and dried fruits, as well as vitamin C with the NAFLD prevalence (p<0.05). In conclusion, a better diet quality as characterized by a higher DQI-I and a higher consumption of vegetables, legumes and fruits was associated with a reduced likelihood of having NAFLD in Hong Kong Chinese.     

非酒精性脂肪性肝病蛋白质组学研究进展

非酒精性脂肪性肝病(nonalcoholic fatty liver disease,NAFLD)是一种常见慢性肝脏疾病,其发病率呈逐年上升趋势,但发病机制尚未明确,诊疗手段仍不完善.蛋白质组学(proteomics)的出现使NAFLD研究有了进一步的发展,相关研究已达21个.目前,蛋白质组学技术可以研究疾病相关的分子改变,从而寻找新的生物标志物和治疗靶标.在此,对蛋白质组学在NAFLD诊断及分期、发病机制和其他相关领域研究进展作一个较为全面的综述.首先,对研究中遇到的研究对象、样本种类、实验方法和标志物特征选择进行经验性总结.其次,除了介绍如何运用蛋白质组学研究病因、危险因素和重要分子在NAFLD发病机制中的作用,还介绍NAFLD发病机制的亚细胞蛋白质组学、修饰蛋白质组学以及蛋白质组学与转录组学相结合的研究实例.此外,对差异蛋白质的分析策略和价值作了重点阐述,收集到一些有望成为NAFLD治疗靶标的候选分子.最后,结合新技术展望研究新空间,以期能够有助于推动蛋白质组学在寻找新的疾病标志物、探索疾病分子机制和治疗靶标中开辟新的途径.     

MicroRNAs in the Pathogenesis of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD), or, more accurately, metabolic associated fatty liver disease, accounts for a large proportion of chronic liver disorders worldwide and is closely associated with other conditions such as cardiovascular disease, obesity, and type 2 diabetes mellitus. NAFLD ranges from simple steatosis to nonalcoholic steatohepatitis (NASH) and can progress to cirrhosis and, eventually, also hepatocellular carcinoma. The morbidity and mortality associated with NAFLD are increasing rapidly year on year. Consequently, there is an urgent need to understand the etiology and pathogenesis of NAFLD and identify effective therapeutic targets. MicroRNAs (miRNAs), important epigenetic factors, have recently been proposed to participate in NAFLD pathogenesis. Here, we review the roles of miRNAs in lipid metabolism, inflammation, apoptosis, fibrosis, hepatic stellate cell activation, insulin resistance, and oxidative stress, key factors that contribute to the occurrence and progression of NAFLD. Additionally, we summarize the role of miRNA-enriched extracellular vesicles in NAFLD. These miRNAs may comprise suitable therapeutic targets for the treatment of this condition.     

非酒精性脂肪肝与脂肪性肝炎动物模型研究进展

非酒精性脂肪肝是无酒精滥用的包括单纯性脂肪肝、脂肪性肝炎、脂肪性肝纤维化和肝硬化的肝病综合征,目前已成为广受关注的肝病医学难题。随着抗脂肪肝药物的深入研究,动物模型制作得到很好发展。近年来,在大鼠、沙鼠、小鼠、兔和小猪等动物种属成功地建立了食物、胃肠外营养与蛋氨酸胆碱缺乏等诱导的单纯性脂肪肝和脂肪性肝炎动物模型,这些模型为研究脂肪肝和脂肪性肝炎的发病机理与治疗提供了机会。每种动物模型各有优缺点,合理应用动物模型能更好地开展脂肪肝病的实验和临床研究。本文综述了非酒精性脂肪肝及脂肪性肝炎动物模型制作方法的若干研究进展。     

非酒精性脂肪性肝病的药物治疗进展

非酒精性脂肪性肝病已日渐成为目前慢性肝病的主要病因,其与肥胖、2型糖尿病和代谢综合征等疾病密切相关,疾病谱主要包括非酒精性单纯性脂肪肝、非酒精性脂肪性肝炎和肝硬化。早期诊断和及时治疗可望减轻NAFLD患者肝炎的严重程度并延缓肝纤维化的进展,减少并发症的出现。目前认为其发病与胰岛素抵抗、氧化应激及脂质过氧化和肠道菌群失调等因素有关。通过饮食调整和适当运动而减轻体重被认为是最基础的治疗措施,但单纯依靠减肥治疗脂肪性肝病(FLD)的效果并不理想,药物在脂肪性肝炎防治中的作用同样不可忽视。目前没有根治这一疾病的特效药物,单纯针对某一发病机制的药物亦难以治愈NAFLD这种复杂的疾病,本文主要从改善胰岛素抵抗、降脂、保肝抗炎及改善肠道菌群等四方面介绍一下本病的药物治疗进展。提倡改变生活方式的非药物治疗与药物干预治疗紧密结合,以取得最理想的治疗效果。     

Association between Serum Atypical Fibroblast Growth Factors 21 and 19 and Pediatric Nonalcoholic Fatty Liver Disease

Atypical fibroblast growth factors (FGF) 21 and 19 play a central role in energy metabolism through the mediation of Klotho coreceptor. Contradictory findings are available about the association of FGF21 and FGF19 with nonalcoholic fatty liver disease (NAFLD) in humans. We investigated the association of serum FGF21, FGF19 and liver Klotho coreceptor with non-alcoholic steatohepatitis (NASH) and fibrosis in children with NAFLD. Serum FGF21 and FGF19 were measured in 84 children with biopsy-proven NAFLD and 23 controls (CTRL). The hepatic expression of Klotho coreceptor was measured in 7 CTRL, 9 patients with NASH (NASH+) and 11 patients without NASH (NASH−). FGF21 and FGF19 showed a tendency to decrease from CTRL (median FGF21 = 196 pg/mL; median FGF19 = 201 pg/mL) to NASH− (FGF21 = 89 pg/mL; FGF19 = 81 pg/mL) to NASH+ patients (FGF21 = 54 pg/mL; FGF19 = 41 pg/mL) (p<0.001 for all comparisons) and were inversely associated with the probability of NASH and fibrosis in children with NAFLD. The hepatic expression of Klotho coreceptor was inversely associated with NASH (R² = 0.87, p<0.0001) and directly associated with serum FGF21 (R² = 0.57, p<0.0001) and FGF19 (R² = 0.67, p<0.0001). In conclusion, serum FGF19 and FGF21 and hepatic Klotho expression are inversely associated with hepatic damage in children with NAFLD and these findings may have important implications for understanding the mechanisms of NAFLD progression.     

代谢正常肥胖个体发生非酒精性脂肪性肝病的相关性研究

目的:探讨代谢正常肥胖(Metabolically healthy obese,MHO)个体与非酒精性脂肪性肝病(Nonalcoholic fatty liver disease,NAFLD)发生的相关性。方法:选择2006年4月～2010年1月来湖南省人民医院体检中心体检人群共4076例,排除过量饮酒者、乙肝标志物阳性者及相关资料不全者共2830例纳入本研究。其中1367例在1～3年后再次体检。记录受检者身高、体重、血压、血脂、空腹血糖、腹部B超结果。NAFLD采用2010年中华医学会肝病学分会诊断标准中影像学诊断定义,行腹部B超检查进行诊断。结果:1.我院体检人群中MHO合并NAFLD者占51.34%,明显高于正常对照组(P=0.000),MHO组发生NAFLD的OR值为19.967(95%CI,12.646-31.533;P=0.000)。2.随访1～3年后,MHO中NAFLD发病率高于正常对照组(44.44%vs 7.02%,OR=10.600,95%CI,4.873-23.058;P=0.000)。结论:MHO个体合并NAFLD比例较正常对照者升高,MHO个体增加NAFLD患病风险。     

A Meta-analysis on Associated Risk of Mortality in Nonalcoholic Fatty Liver Disease

ObjectiveNonalcoholic fatty liver disease (NAFLD) affects much of the worldwide population and poses a significant burden to the global healthcare. The rising numbers of individuals with NAFLD and instances of mortality point toward the importance of understanding the association causes of mortality in NAFLD. This meta-analysis aimed to seek the associations of NAFLD with all-cause, cardiovascular disease (CVD)-related, liver-related, and cancer-related mortality.MethodsMEDLINE and Embase were searched for articles relating to causes of mortality between NAFLD and non-NAFLD. The DerSimonian and Laird random-effects model was used to analyze adjusted hazard ratios (HR), and a sensitivity analysis was conducted to reduce heterogeneity through a graphical display of study heterogeneity.ResultsFifteen studies involving 10 286 490 patients were included. Individuals with NAFLD exhibited an increased risk of all-cause mortality (HR, 1.32; 95% CI, 1.09-1.59; P < .01; I² = 96.00%), CVD-related mortality (HR, 1.22; 95% CI, 1.06-1.41; P < .01; I² = 81.00%), and cancer-related mortality (HR, 1.67; 95% CI, 1.15-2.41; P < .01; I² = 95.00%). However, no significant association was found between liver-related mortality and NAFLD (HR, 3.58; 95% CI, 0.69-18.46; P =.13; I² = 96.00%). The sensitivity analysis conducted with graphic display of heterogeneity and only population-based studies found similar results.ConclusionNAFLD was associated with an increased risk of all-cause, CVD-related, and cancer-related mortality but not liver-related mortality. The finding is likely because of low fibrosis prevalence in the community. However, the significant burden in other causes of mortality beyond the liver points to a need for multidisciplinary efforts to reduce the mortality risks.     

High Serum Uric Acid Increases the Risk for Nonalcoholic Fatty Liver Disease: A Prospective Observational Study

Nonalcoholic fatty liver disease (NAFLD) is a common form of chronic liver disease, and serum uric acid is observed to be significantly elevated in NAFLD patients. However, whether this elevation is causal, a bystander, or a consequence of NAFLD remains unclear. We performed a population-based prospective study among the employees of Zhenhai Refining & Chemical Company Ltd., Ningbo, China to investigate whether the elevation of serum uric acid has a casual role for NAFLD. A total of 6890 initially NAFLD-free subjects were followed up for 3 years. Overall, 11.80% (813/6890) subjects developed NAFLD over 3 years of follow-up. The cumulative incidence of NAFLD increased with progressively higher baseline serum uric acid levels (the cumulative incidence was 7.2%, 9.5%, 11.5%, 13.8%, and 17.2% in quintile 1, quintile 2, 3, 4 and 5, respectively; P value for trend <0.001). Cox proportional hazards regression analyses showed that serum uric acid levels were independently and positively associated with the risk for incident NAFLD; the age-, gender- and metabolic syndrome adjusted hazard ratio (95% CI) for the subjects in quintile 2, 3, 4 and 5 versus quintile 1 was 1.18 (0.91–1.54), 1.32 (1.03–1.70), 1.39 (1.09–1.78) and 1.50 (1.18–1.92), respectively. Taken together, our prospective observational study showed that elevation of serum uric acid levels independently predicts increase risk for incident NAFLD.