Modelling Porcine NAFLD by Deletion of Leptin and defining the role of AMPK in hepatic fibrosis
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ABSTRACT: Liver fibrosis occurs during chronic liver disease. Advanced liver fibrosis results in cirrhosis, liver failure and often requires liver transplantation. However, due to the lack of human models, mechanisms underlining the pathogenesis of liver fibrosis remain unclear. Recent studies implicated a central role of deranged lipid metabolism in its pathogenesis. In this study, we generated LEPTIN-deficient (LEPTIN-/-) pigs using zinc finger nuclease technology to investigate the mechanisms of liver fibrosis associated with obesity. The LEPTIN-/- pigs showed increased body fat and significant insulin resistance by 12 months of age. To resemble non-alcoholic fatty liver disease (NAFLD) patients, LEPTIN-/- pig developed the phenotypic features of fatty liver, non-alcoholic steatohepatitis (NASH) and hepatic fibrosis with age. Meanwhile, LEPTIN absence reduced phosphorylation of JAK2-STAT3 and AMPK. The alteration of JAK2-STAT3 enhanced fatty acid β-oxidation, whereas inactivation of AMPK led to mitochondrial autophagy, and both contributed to increased oxidative stress in hepatocytes. Although Leptin deletion in the rat liver altered JAK2-STAT3 phosphorylation, it activated the AMPK pathway and prevented liver fibrogenesis in contrast with the LEPTIN-/- pig. To our knowledge, the LEPTIN-/- pig provides the first model recapitulating the full pathogenesis of NAFLD and its progression toward liver fibrosis. The activity of AMPK signaling pathway suggests a potential target for development of new strategies for the diagnosis and treatment of NAFLD.
Project description:The aim of this project was to profile the proteome of mouse-derived liver in order to identify those that showed significant quantitative different proteins among leptin-deficient (db/db) mouse, the genetic non-alcoholic fatty liver disease (NAFLD) mouse model and their lean BKS mouse group.
Project description:The aim of this project was to profile the proteome of mouse-derived serum in order to identify those that showed significant quantitative different proteins among leptin-deficient (db/db) mouse, the genetic non-alcoholic fatty liver disease (NAFLD) mouse model and their lean bks mouse group.
Project description:Non-alcoholic fatty liver (NAFL) has the potential to progress to non-alcoholic steatohepatitis (NASH) or to promote type 2 diabetes mellitus (T2DM). However, NASH and T2DM do not always develop coordinately. We established rat models of NAFL, NASH, and NAFL + T2DM to recapitulate different phenotypes associated with NAFLD and its progression. Microarrays were used to identify hepatic gene expression changes in each of these models. The goal is to identify a predictor of different NAFLD progressions. Non-alcoholic fatty liver disease (NAFLD) is recognized as a low-grade systemic inflammatory state with both hepatic and extra-hepatic manifestations. We aimed to identify common key regulators and adaptive pathways in different NAFLD phenotypes. NAFL, NASH and NAFL+T2DM rat models were used to represent simple fatty liver, fatty liver with severe hepatic manifestations, and fatty liver with severe metabolic manifestations, respectively. We applied microarray analysis to characterize the key regulators and adaptive pathways in different NAFLD phenotypes. There are 12 samples in our study which belonged to 4 groups, and each group contains 3 different samples.
Project description:Non-alcoholic fatty liver disease (NAFLD) has become a growing public health problem. However, the complicated pathogenesis of NAFLD contributes to the deficiency of effective clinical treatment. Here, we elucidated that liver-specific loss of Arid2 induced hepatic steatosis and this progression could be exacerbated by HFD. Mechanistic study revealed that ARID2 repressed JAK2-STAT5-PPARγ signaling pathway by promoting the ubiquitination of JAK2, which was mediated by NEDD4L, a novel E3 ligase for JAK2. ChIP assay revealed that ARID2 recruited CARM1 to increase H3R17me2 level at NEDD4L promoter and activated the transcription of NEDD4L. Moreover, inhibition of Jak2 by Fedratinib in liver-specific Arid2 knockout mice alleviated HFD-induced hepatic steatosis. Downregulation of ARID2 and the reverse correlation between ARID2 and JAK2 were also observed in clinical samples. Therefore, our study has revealed an important role of ARID2 in the development of NAFLD and provides a potential therapeutic strategy for NAFLD.
Project description:Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of disease that ranges from simple steatosis, to inflammatory form non-alcoholic steatohepatitis (NASH), cirrhosis, and up to hepatocellular carcinoma. While NASH usually takes decades to develop at a rate of one stage per seven years, in the case of post-trasplant NASH (pt-NASH) develops fibrosis much more rapidly, with almost 50% of liver transplant recipients presenting stage 3 fibrosis by 5 years post-transplant. Archived fresh-frozen transplanted liver biopsy samples from four liver biopsy samples with evidence of NASH (2 recurrent and 2 de novo), two with simple steatosis (both de novo), and five with normal histology as controls had their transcriptome sequenced in two batches for deeper coverage.
Project description:Non-alcoholic fatty liver disease (NAFLD) is characterized by excess lipid accumulation in hepatocytes and reprepresents a huge public health problem owing to its propensity to progress to non-alcoholic steatohepatitis (NASH), fibrosis, and liver failure. The lipids stored in hepatic steatosis are primarily triglycerides (TGs) synthesized by two acyl CoA:diacylglycerol acyltransferase (DGAT) enzymes. Either DGAT1 or DGAT2 catalyzes this reaction, and these enzymes have been suggested to differentially utilize exogenous or endogenously synthesized fatty acids, with DGAT2 being linked to storage of fatty acids from de novo lipogenesis, a process that is increased in NAFLD. However, whether DGAT2 is more responsible for lipid accumulation in NAFLD and the progression to fibrosis is currently unknown. Also, it is unresolved whether DGAT2 can be safely inhibited as a therapy for NAFLD. Here we induced NAFLD-like disease in mice by feeding a diet rich in fructose, saturated fat, and cholesterol and found that hepatocyte-specfici Dgat2 deficiency reduced expression of de novo lipogenesis genes and lowered liver TGs by ~70%. Importantly, the reduction of steatosis was not accompanied by increased inflammation or fibrosis, and insulin and glucose metabolism were unchanged. Conclusion: This study suggests that hepatic DGAT2 deficiency successfully reduced diet-induced hepatic steatosis and supports the development of DGAT2 inhibitors as a therapeutic strategy for treating NAFLD and preventing downstream consequences.
Project description:The pathophysiological mechanisms that drive non-alcoholic fatty liver disease (NAFLD) progression remain poorly understood. This multicenter study characterized the transcriptional changes that occur as liver disease progresses. 216 snap frozen liver biopsies, comprising 206 NAFLD cases with different fibrosis stages and 10 controls were studied. Samples underwent high-throughput RNA sequencing. This study provides novel insights into transcriptional changes during liver disease evolution and progression as well as proof of principle that transcriptomic changes reveal potentially tractable biomarkers for NAFLD fibrosis.
Project description:Non-alcoholic fatty liver disease (NAFLD) is characterized by a series of pathological changes that can progress from simple fatty liver disease to non-alcoholic steatohepatitis (NASH). The objective of this study is to describe changes in global gene expression associated with the progression of NAFLD. This study is focused on the expression levels of genes responsible for the absorption, distribution, metabolism and excretion (ADME) of drugs. Differential gene expression between three clinically defined pathological groups; normal, steatosis and NASH was analyzed. The samples were diagnosed as normal, steatotic, NASH with fatty liver (NASH fatty) and NASH without fatty liver (NASH NF). Genome-wide mRNA levels in samples of human liver tissue were assayed with Affymetrix GeneChipM-. Human 1.0ST arrays
Project description:C57BL/6 mice received methionine/choline deficient (MCD) diet to establish the model of non-alcoholic fatty liver disease (NAFLD) with or without Diethyldithiocarbamate (DDC) treatment. DDC improves hepatic steatosis, ballooning, inflammation and fibrosis in rodent models of NAFLD through modulating lipid metabolism and oxidative stress.
Project description:We aimed to develop an in vitro system that would recapitulate the key features of Non-Alcoholic Fatty Liver Disease (NAFLD). We took advantage of human pluripotent stem cells (hIPSCs) to establish 3D cultures of hIPSCs-derived hepatocytes to study NAFLD pathogenesis in vitro. Cultures were challenged with free fatty acid to mimic NAFLD, and transcriptomic analyses were used to confirm the presence of a NAFLD signature.