Breath biomarkers and non-alcoholic fatty liver disease: Preliminary observations

Breath biomarkers have the potential to offer information that is similar to conventional clinical tests or they are entirely unique. Preliminary data support the use of breath biomarkers in the study of liver disease, in particular non-alcoholic fatty liver disease (NAFLD). It was evaluated whether breath ethanol, ethane, sulfur compounds and acetone would be associated with hepatic histopathology amongst morbidly obese patients presenting for bariatric surgery. Breath samples were collected during a preoperative visit and compared with liver biopsies obtained during the surgery. A Student's two-tailed t-test was used to compare differences between the two groups. Linear regression was used to analyse associations between the concentrations of breath molecules and independent predictor variables. It was found that breath ethanol, ethane and acetone can be useful biomarkers in patients with NAFLD. In particular, breath ethanol can be associated with hepatic steatosis, and breath acetone can be associated with non-alcoholic steatohepatitis.     

三种啮齿类动物非酒精性脂肪肝形成及机制探讨

目的 分析物种差异对NAFLD模型复制的影响,探讨不同鼠种NAFLD形成及其机制.方法 长爪沙鼠、SD大鼠、ICR小鼠各20只,按种属随机分为对照组及模型组,对照组给予普通饲料,模型组给予高脂饲料.16周后,观察肝脏HE及Mallory三色染色病理变化,计算肝指数,检测血清血脂(CHO、TG、LDL-c、HDL-c)、肝功能(GOP、GPT)及肝组织中抗氧化酶(SOD、GSH-PX、CAT)活性及羟脯氨酸(Hyp)、丙二醛(MDA)、游离脂肪酸(FFA)水平.结果 与对照组比较,各模型组:沙鼠Hyp、CHO、TG、LDL-c、HDL-c、肝指数、GOP、GPT、MDA、FFA均升高,SOD、GSH-PX、CAT活性降低(P＜0.05,P＜0.01),肝脏出现纤维化;大鼠CHO、肝指数、GOP、GPT、FFA、SOD活性升高,MDA含量、GSH-PX、CAT活性降低(P ＜0.05,P＜0.01),有局灶性脂肪肝炎;小鼠CHO、LDL-c、HDL-c、肝指数、CAT活性升高,MDA含量降低(P ＜0.05,P＜0.01),肝脏病理正常.结论 三种动物在脂质代谢、肝功能、氧化应激等方面有显著的差异,并形成了不同的NAFLD模型:沙鼠形成伴高TG、CHO血症的肝纤维化模型、大鼠形成伴高CHO血症的局灶性脂肪肝炎模型、小鼠形成高胆固醇血症模型但肝脏未发生明显的病理改变.     

固醇调节元件结合蛋白2信号通路与非酒精性脂肪性肝病

非酒精性脂肪性肝病（non-alcoholic fatty liver disease,NAFLD）是以肝细胞内甘油三酯和胆固醇等脂毒性脂肪过度沉积为主要特征的一种临床获得性代谢综合征。最新研究表明,NAFLD向非酒精性脂肪肝炎(NASH)进展时,肝内胆固醇积累可能较甘油三酯更具有细胞毒性风险。固醇调节元件结合蛋白2（sterol regulatory element-binding protein 2,SREBP2）是脂质代谢重要的核转录因子之一,主要调控胆固醇的生物合成和体内平衡。SREBP2及其靶基因调控的胆固醇异常是引起非酒精性脂肪肝病发生发展的重要因素之一。因此,认识SREBP2信号通路中,上下游各因素的表达调控作用与NAFLD发病机制之间关系,就显得非常重要。本文总结了受SREBP2调控表达的靶基因的特点,着重介绍SREBP2调控胆固醇体内合成与平衡的信号通路与NAFLD发病机制之间关系,为研究和指导治疗NAFLD及其代谢性疾病提供新的思路。     

Association between the Pro12Ala polymorphism of PPAR-γ gene and the non-alcoholic fatty liver disease: A meta-analysis

Several studies have been conducted to examine the association between PPAR-γ2 Pro12Ala polymorphism and non-alcoholic fatty liver disease (NAFLD), but the results remain inconsistent. In this study, a meta-analysis was performed to assess the association of PPAR-γ Pro12Ala polymorphism with NAFLD risk. A total of 8 case–control studies, including 1697 cases and 2427 controls, were selected. Pooled odds ratio (OR) with 95% confidence interval (CI) was calculated using fixed- or random-effects model. Overall, no evidence has indicated that the Pro12Ala polymorphism was associated with the susceptibility to NAFLD. Besides, stratified analysis with ethnicity also indicated that no significant association between PPAR-γ Pro12Ala and the risk of NAFLD under all for genetic model in both Asian and Caucasian populations was observed. This meta-analysis indicated that the Pro12Ala polymorphism is not associated with NAFLD risk. Large and well-designed studies are warranted to validate our findings.     

胆汁酸受体在非酒精性脂肪性肝病中的作用

非酒精性脂肪性肝病(non-alcoholic fatty liver disease, NAFLD)作为一种慢性肝病,在全球的发病率逐年递增。胰岛素抵抗和脂质代谢紊乱,以及随后的炎症反应和纤维化的激活,在其发生发展过程中发挥重要作用。但是对其认识仍很欠缺,且临床尚缺乏有效的药物。科研人员正极力探索NAFLD的相关病因及治疗的新的突破口。胆汁酸是在肝中合成的众多代谢产物之一。除帮助脂肪消化吸收外,胆汁酸还作为信号分子激活胆汁酸受体,一种重要的转录调节因子而发挥效应,对维持机体正常生理代谢至关重要。越来越多的证据表明,胆汁酸受体的功能与NAFLD的发生发展关系密切,研究其相关的作用与功能可为治疗NAFLD提供新见解和药物治疗靶点。本文就胆汁酸受体包括核受体,诸如法尼醇X受体 (farnesoid X receptor, FXR)、孕烷X受体 (pregnane X receptor ,PXR)等,和细胞表面受体,诸如跨膜G蛋白偶联胆汁酸受体5(transmembrane G protein-coupled receptor 5, TGR5)、鞘氨醇-1-磷酸受体2(phingosine-1-phosphate receptor 2, S1PR2)和毒蕈碱胆碱受体3 (M3 muscarinic receptor, M3R)通过调节胆汁酸稳态、脂质和糖代谢、能量代谢、肝的炎症和纤维化等参与NAFLD发病机制的研究进展进行总结,并进一步阐述了胆汁酸受体激动剂对NAFLD的治疗现状,以期更全面地了解NAFLD的发病机制以及为治疗找到更有效的途径。     

Tumor necrosis factor-α accelerates apoptosis of steatotic hepatocytes from a murine model of non-alcoholic fatty liver disease

Non-alcoholic steatohepatitis (NASH) develops in a subset of patients with non-alcoholic fatty liver disease (NAFLD), but the exact mechanisms involved in the progression of NAFLD to NASH remain poorly understood. We investigated the role of tumor necrosis factor-α (TNF-α) in the apoptosis of hepatocytes that is related to the severity of NASH. We separated primary hepatocytes from the NAFLD liver caused by a high-fat diet. The production of intracellular reactive oxygen species was increased in steatotic hepatocytes, which were also sensitive to TNF-α. This factor induced significant apoptosis through the signal-regulating kinase 1 (ASK1) and c-Jun N-terminal kinase (JNK) pathway. We describe here a novel culture model of steatotic hepatocytes separated from the NAFLD liver, and demonstrate that TNF-α induces their apoptosis in vitro.     

非酒精性脂肪性肝病的发病机制及治疗进展

近年来,随着人们生活水平的提高,脂肪性肝病的发病率明显上升,且患病年龄趋于低龄化,已经成为严重危害我国人民健康的常见疾病,我国非酒精性脂肪性肝病的发病率明显高于酒精性脂肪性肝病。本文主要对NAFLD的发病机制及相关治疗进展做简要的综述。NAFLD的发病机制与胰岛素抵抗、氧化应激、代谢综合征、脂肪细胞因子的作用、内质网应激、及铁超载等多种因素有关。NAFLD的治疗可以从防治原发病或相关危险因素、基础治疗(行为或生活方式干预;调整饮食;运动疗法)、药物治疗以及手术治疗等方面进行。了解国际上NAFLD的发病机制以及相关治疗进展,对遏制非酒精性脂肪性肝病的发生、发展趋势有着十分重要的意义。     

New insight into inter-organ crosstalk contributing to the pathogenesis of nonalcoholic fatty liver disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver dysfunction and a significant global health problem with substantial rise in prevalence over the last decades. It is becoming increasingly clear that NALFD is not only predominantly a hepatic manifestation of metabolic syndrome, but also involves extra-hepatic organs and regulatory pathways. Therapeutic options are limited for the treatment of NAFLD. Accordingly, a better understanding of the pathogenesis of NAFLD is critical for gaining new insight into the regulatory network of NAFLD and for identifying new targets for the prevention and treatment of NAFLD. In this review, we emphasize on the current understanding of the inter-organ crosstalk between the liver and peripheral organs that contributing to the pathogenesis of NAFLD.     

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。     

肝细胞甘油三酯代谢途径异常与脂肪肝

脂肪肝(NAFLD)既可是一个独立的疾病,也可是一类疾病的伴发疾病,肥胖患者、脂肪营养不良症患者、糖尿病患者均伴发脂肪肝。脂肪肝时肝细胞内蓄积的脂质多为甘油三酯,因此肝细胞甘油三酯代谢紊乱是脂肪肝发生最主要原因。肝细胞甘油三酯蓄积会破坏其对胰岛素敏感性,促进肝糖异生导致高血糖,也可引起肝细胞极低密度脂蛋白分泌增加,升高血脂。本文详细阐述肝细胞甘油三酯代谢途径的重要步骤,探讨这些步骤异常与脂肪肝之间的关系,为脂肪肝药物设计提供新靶点。的每条通路的各个步骤,探讨这些步骤异常与脂肪肝之间的关系,为脂肪肝药物设计提供新靶点。     

Integrating the contributions of mitochondrial oxidative metabolism to lipotoxicity and inflammation in NAFLD pathogenesis

The prevalence of non-alcoholic fatty liver disease (NAFLD) is increasing globally. NAFLD includes non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH). NASH is the pathological form of the disease characterized by liver steatosis, inflammation, cell injury, and fibrosis. A fundamental contributor to NASH is the imbalance between lipid accretion and disposal. The accumulation of liver lipids precipitates lipotoxicity and the inflammatory contributions to disease progression. This review defines the role of dysregulated of lipid disposal in NAFLD pathophysiology. The characteristic changes in mitochondrial oxidative metabolism pathways and the factors promoting these changes across the spectrum of NAFLD severity are detailed. This includes pathway-specific and integrative perturbations in mitochondrial β-oxidation, citric acid cycle flux, oxidative phosphorylation, and ketogenesis. Moreover, well-recognized and emerging mechanisms through which dysregulated mitochondrial oxidative metabolism mediates inflammation, fibrosis, and disease progression are highlighted.     

Probiotics: A possible specific liver drug for non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is and will continue to be a major liver health issue worldwide in the coming decades. There are no leading drug candidates at this point, although there are several promising concepts in drug development. Recent studies have proposed a possible role of intestinal bacterial overgrowth in the development of non-alcoholic steatohepatitis, thus indicated probiotics maybe a potential specific liver drug for NAFLD in the future.     

非酒精性脂肪性肝病的研究进展

非酒精性脂肪性肝病(NAFLD)在西方国家较为常见,近年来在我国的发病呈上升趋势,且发展逐渐低龄化。非酒精性脂肪性肝病患者可能因持续性肝损伤而导致纤维化进展,可与慢性病毒性肝炎和酒精性肝病一样发展到终末期肝硬化,并出现肝硬化严重并发症,也有可能发展成肝癌,最终需要肝移植治疗。它严重危害人类的健康,影响人类的生活及生存质量。多因素的发病机制使其愈来愈被人们所重视,研究和了解非酒精性脂肪性肝病的流行病学、发病机制、诊断及治疗方法,对人类非常重要,如果在疾病的早期,也就是单纯性脂肪肝阶段就对疾病进行干预,这样可以取得很好的治疗效果,NAFLD是人类在本世纪需要面对的疾病之一,因此研究它的发病机制及治疗方法是非常必要的。     

Endoplasmic reticulum stress and Oxidative stress in the pathogenesis of Non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome. The underlying causes of the disease progression in NAFLD are unclear. Recent evidences suggest endoplasmic reticulum stress in the development of lipid droplets (steatosis) and subsequent generation of reactive oxygen species (ROS) in the progression to non-alcoholic steatohepatitis (NASH). The signalling pathway activated by disruption of endoplasmic reticulum (ER) homoeostasis, called as unfolded protein response, is linked with membrane biosynthesis, insulin action, inflammation and apoptosis. ROS are important mediators of inflammation. Protein folding in ER is linked to ROS. Therefore understanding the basic mechanisms that lead to ER stress and ROS in NAFLD have become the topics of immense interest. The present review focuses on the role of ER stress and ROS in the pathogenesis of NAFLD. We also highlight the cross talk between ER stress and oxidative stress which suggest and encourage the development of therapeutics for NAFLD. Further we have reviewed various strategies used for the management of NAFLD/NASH and limitations of such strategies. Our review therefore highlights the need for newer strategies with regards to ER stress and oxidative stress.     

一种非酒精性脂肪性肝病的超声影像人工智能辅助诊断系统开发

摘要 目的：结合人工智能方法设计针对肝脏超声影像的辅助诊断系统，辅助医生对大样本肝脏超声影像数据的标准化和高效化诊断，实现基于肝脏超声图像的非酒精性脂肪性肝病的精准诊断。方法：通过开发肝脏超声影像的识别与分类、脂肪肝分级分析和肝脏脂肪含量定量分析三个模块，建立一套非酒精性脂肪性肝病的超声影像人工智能辅助诊断系统，该系统能够自动区分输入到系统中不同采样视野的超声影像类型，并对肝脏超声图像进行数字化分析，给出待测超声图像是否呈现脂肪肝以及其肝脏脂肪含量的百分比值。结果：本研究中的超声图像识别分类模块可高通量区分出肝肾比图像和衰减率图像的两类超声影像，其分类的准确率达100%。脂肪肝分级分析模块在测试集数据的准确率达到84%，展现出可胜任辅助医生诊断的能力。基于人工肝脏脂肪含量定量方法开发的肝脏脂肪含量定量分析模块的准确率达到67.74%。结论：本研究已开发出一套基于肝脏超声影像的智能辅助诊断系统，可以辅助医生快速、简单、无创地筛选出潜在患有脂肪肝的患者，虽然现阶段实现肝脏脂肪定量分析仍有难度，但已展现出较大的临床应用潜力。     

LncRNA MAYA promotes iron overload and hepatocyte senescence through inhibition of YAP in non-alcoholic fatty liver disease

Although recent evidence has shown that hepatocyte senescence plays a crucial role in the pathogenesis and development of non-alcoholic fatty liver disease (NAFLD), the mechanism is still not clear. The purpose of this study was to investigate the signal transduction pathways involved in the senescence of hepatocyte, in order to provide a potential strategy for blocking the process of NAFLD. The results confirmed that hepatocyte senescence occurred in HFD-fed Golden hamsters and PA-treated LO2 cells as manifested by increased levels of senescence marker SA-β-gal, p16 and p21, heterochromatin marker H3K9me3, DNA damage marker γ-H2AX and decreased activity of telomerase. Further studies demonstrated that iron overload could promote the senescence of hepatocyte, whereas the overexpression of Yes-associated protein (YAP) could blunt iron overload and alleviate the senescence of hepatocyte. Of importance, depression of lncRNA MAYA (MAYA) reduced iron overload and cellular senescence via promotion of YAP in PA-treated hepatocytes. These effects were further supported by in vivo experiments. In conclusion, these data suggested that inhibition of MAYA could up-regulate YAP, which might repress hepatocyte senescence through modulating iron overload. In addition, these findings provided a promising option for heading off the development of NAFLD by abrogating hepatocyte senescence.     

Lipotoxicity and steatohepatitis in an overfed mouse model for non-alcoholic fatty liver disease

The major risk factors for non-alcoholic fatty liver disease (NAFLD) are obesity, insulin resistance and dyslipidemia. The cause for progression from the steatosis stage to the inflammatory condition (non-alcoholic steatohepatitis (NASH)) remains elusive at present. Aim of this study was to test whether the different stages of NAFLD as well as the associated metabolic abnormalities can be recreated in time in an overfed mouse model and study the mechanisms underlying the transition from steatosis to NASH.Male C57Bl/6J mice were subjected to continuous intragastric overfeeding with a high-fat liquid diet (HFLD) for different time periods. Mice fed a solid high-fat diet (HFD) ad libitum served as controls. Liver histology and metabolic characteristics of liver, white adipose tisue (WAT) and plasma were studied.Both HFD-fed and HFLD-overfed mice initially developed liver steatosis, but only the latter progressed in time to NASH. NASH coincided with obesity, hyperinsulinemia, loss of liver glycogen and hepatic endoplasmatic reticulum stress. Peroxisome proliferator-activated receptor γ (Pparγ), fibroblast growth factor 21 (Fgf21), fatty acid binding protein (Fabp) and fatty acid translocase (CD36) were induced exclusively in the livers of the HFLD-overfed mice. Inflammation, reduced adiponectin expression and altered expression of genes that influence adipogenic capacity were only observed in WAT of HFLD-overfed mice.In conclusion: this dietary mouse model displays the different stages and the metabolic settings often found in human NAFLD. Lipotoxicity due to compromised adipose tissue function is likely associated with the progression to NASH, but whether this is cause or consequence remains to be established.     

视黄醇结合蛋白4在非酒精性脂肪肝病大鼠组织中的表达

目的:视黄醇结合蛋白4(RBP4)在非酒精性肝脂肪变模型大鼠中的表达情况,以探求其在疾病发生、发展中的意义。方法:40只wistar大鼠随机分为对照组和造模组,分析各组在2、4、6、8周4个时间点血清ALT、AST、TG、TC的变化及肝组织RBP4的表达情况。结果:随着造模时间延长,造模组大鼠肝脏脂肪变越来越明显,血清ALT、AST、TG、TC逐渐升高(p<0.05)。造模组肝组织RBP4的mRNA的表达随造模时间逐渐增强;造模组免疫组化结果发现,RBP4的表达随造模时间逐渐增强(p<0.05)。结论:在大鼠非酒精性脂肪肝模型中,RBP4的表达随造模时间延长而增加,与同期对照组相比有统计学差异,因此RBP4可能作为一个敏感的指标反映非酒精性脂肪肝的发生及发展情况。