The identification of genes altered by RORα in progression of non-alcoholic steatohepatitis (NASH)
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ABSTRACT: Purpose: To identify the target genes of RORα associated with development of NASH Methods: RNA isolation for sequencing analysis from liver tissues of High fat diet (HFD)-fed RORα-LKO and RORα f/f mice and mRNA-sequencing Conclusion: When calcuated by dividing the normalized read count of HFD-fed RORα-LKO by that of RORαf/f,.there are 8505 genes altered by RORα deletion (cut-off, 0.8-fold, 1.5-fold).
Project description:The mechanisms underlying the progression of non-alcoholic steatohepatitis (NASH) are not completely elucidated. In this study we have integrated gene expression profiling of liver biopsies of NASH patients with translational studies in a mouse model of steatohepatitis and with pharmacological interventions in isolated hepatocytes to identify a novel mechanism implicated in the pathogenesis of NASH. By using high-density oligonucleotide microarray analysis we identified a significant enrichment of known genes involved in the multi-step catalysis of long chain polyunsaturated fatty acids, including delta-5 and 6 desaturases. A combined inhibitor of delta-5 and delta-6 desaturases significantly reduced intracellular lipid accumulation and inflammatory gene expression in isolated hepatocytes. Gas chromatography analysis revealed impaired delta-5 desaturase activity toward the omega-3 pathway in livers from mice with high-fat diet (HFD)-induced NASH. Consistently, restoration of omega-3 index in transgenic fat-1 mice expressing an omega-3 desaturase, which allows the endogenous conversion of omega-6 into omega-3 fatty acids, produced a significant reduction in hepatic insulin resistance, hepatic steatosis, macrophage infiltration and necroinflammatory liver injury, accompanied by attenuated expression of genes involved in inflammation, fatty acid uptake and lipogenesis. These results were comparable to those obtained in a group of mice receiving a HFD supplemented with EPA/DHA. Of interest, hepatocytes from fat-1 mice or supplemented with EPA exhibited synergistic anti-steatotic and anti-inflammatory actions with the delta-5/ delta-6 inhibitor. Conclusion: These findings indicate that both endogenous and exogenous restoration of the hepatic balance between omega-6 and omega-3 fatty acids and/or modulation of desaturase activities exert preventive actions in NASH. The complete database comprised the expression measurements of 18185 genes for liver sample groups: 8 non-alcoholic steatohepatitis (NASH ) and 7 control samples. This dataset is part of the TransQST collection.
Project description:The mechanisms underlying the progression of non-alcoholic steatohepatitis (NASH) are not completely elucidated. In this study we have integrated gene expression profiling of liver biopsies of NASH patients with translational studies in a mouse model of steatohepatitis and with pharmacological interventions in isolated hepatocytes to identify a novel mechanism implicated in the pathogenesis of NASH. By using high-density oligonucleotide microarray analysis we identified a significant enrichment of known genes involved in the multi-step catalysis of long chain polyunsaturated fatty acids, including delta-5 and 6 desaturases. A combined inhibitor of delta-5 and delta-6 desaturases significantly reduced intracellular lipid accumulation and inflammatory gene expression in isolated hepatocytes. Gas chromatography analysis revealed impaired delta-5 desaturase activity toward the omega-3 pathway in livers from mice with high-fat diet (HFD)-induced NASH. Consistently, restoration of omega-3 index in transgenic fat-1 mice expressing an omega-3 desaturase, which allows the endogenous conversion of omega-6 into omega-3 fatty acids, produced a significant reduction in hepatic insulin resistance, hepatic steatosis, macrophage infiltration and necroinflammatory liver injury, accompanied by attenuated expression of genes involved in inflammation, fatty acid uptake and lipogenesis. These results were comparable to those obtained in a group of mice receiving a HFD supplemented with EPA/DHA. Of interest, hepatocytes from fat-1 mice or supplemented with EPA exhibited synergistic anti-steatotic and anti-inflammatory actions with the delta-5/ delta-6 inhibitor. Conclusion: These findings indicate that both endogenous and exogenous restoration of the hepatic balance between omega-6 and omega-3 fatty acids and/or modulation of desaturase activities exert preventive actions in NASH.
Project description:The hallmark of non-alcoholic fatty liver disease (NAFLD) is excessive fatty accumulation in the hepatocytes, which may be an isolated event (non-alcoholic fatty liver, NAFL) or accompanied by evidence of inflammation and cell injury with or without fibrosis (non-alcoholic steatohepatitis, NASH). NASH, the more aggressive form of NAFLD, may progress to cirrhosis and hepatocellular carcinoma. Since NASH is estimated to overtake hepatitis C virus infection as the leading cause of liver transplantation in the US in the coming decade, and there are no current FDA-approved therapies for this disease, the need to find appropriate therapeutic targets is now more urgent than ever before. Diet and other lifestyle modifications have always been difficult to maintain and this approach alone has not slowed the rising tide of the disease. While the results of traditional therapies such as vitamin E and pioglitazone have been significant for steatosis and inflammation, they have had no effect on fibrosis, which is the strongest indicator of mortality in this condition. However, the understanding of the pathogenesis and progression of NASH has evolved and several promising novel therapies to target and possibly reverse fibrosis are being evaluated, making the future outlook of NASH therapy more optimistic.
Project description:To investigate gene expression changes induced by LPIAT1 depletion, Lpiat1F/F and LKO mice were fed high fat diet (HFD) or chow for 18 weeks from 6 weels old and microarray gene profiling were performed. Categorization of the differentially expressed genes between HFD-fed Lpiat1f/f and LKO mice, in relation to their functions in biological pathways, revealed an enrichment of genes involved in inflammation and fibrosis
Project description:Ginsenosides have offered a wide array of beneficial roles in the pharmacological regulation of hepatic metabolic syndromes, including non-alcoholic steatohepatitis (NASH), non-alcoholic fatty liver disease (NAFLD), and obesity. Of the numerous ginsenosides, Rg3 has been widely investigated, but there have been few studies of gypenosides (Gyp). Particularly, no study on Gyp LXXV has been reported to date. Here, to firstly explore the pharmacological effects of Gyp LXXV against NASH and the related mechanism, methionine- and choline-deficient (MCD) diet-induced NASH mice and hepatic cells (stellate cells, hepatic macrophages, and hepatocytes) were selected. Gyp LXXV exhibited markedly alleviated MCD diet-induced hepatic injury, inflammation, and fibrosis by down-regulating hepatic fibrosis markers such as α-smooth muscle actin(α-SMA), collagen1, transforming growth factors-β (TGF-β1), tumor necrosis factor-α (TNF-α), MCP-1, interleukin (IL)-1β, nuclear factor κB (NFκB), and GRP78. Remarkably, histopathological studies confirmed that 15 mg/kg of Gyp LXXV administration to MCD diet-induced mice led to effective prevention of liver injury, lipid accumulation, and activation of hepatic macrophages, indicating that Gyp LXXV might be a potential anti-NASH drug.
Project description:In an effort to study gene expression modulated by RORɣt and RORα in human Th17 cells, global gene expression of human CD4 T cells activated under Th17 skewing conditions was profiled by RNA sequencing. RORɣt and RORα signature genes were identified in these Th17 cells treated with specific siRNAs to knock down RORɣt or RORα expression. In addition, selective small molecule RORɣt modulators were also utilized as pharmacological tools in RORɣt signature gene identification.
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 steatohepatitis (NASH) is a severe form of non-alcoholic fatty liver disease (NAFLD), in which most patients exhibit non-progressive, non-alcoholic fatty liver (NAFL) attributable to simple steatosis. Multiple hits, including genetic differences, fat accumulation, insulin resistance and intestinal microbiota changes, account for the progression of NASH. NAFLD is strongly associated with obesity, which induces adipokine secretion, endoplasmic reticulum (ER) and oxidative stress at the cellular level, which in turn induces hepatic steatosis, inflammation and fibrosis. Among these factors, gut microbiota are acknowledged as having an important role in initiating this multifactorial disease. Oxidative stress is considered to be a key contributor in the progression from NAFL to NASH. Macrophage infiltration is apparent in NAFL and NASH, while T-cell infiltration is apparent in NASH. Although several clinical trials have shown that antioxidative therapy with vitamin E can effectively control hepatitis pathology in the short term, the long-term effects remain obscure and have often proved to be ineffective in many other diseases. Several long-term antioxidant protocols have failed to reduce mortality. New treatment modalities that incorporate current understanding of NAFLD molecular pathogenesis must be considered.
Project description:Non-alcoholic fatty liver disease (NAFLD) is a progressive liver disease characterized by dysregulated lipid metabolism and chronic inflammation ultimately resulting in fibrosis. Untreated, NAFLD may progress to non-alcoholic steatohepatitis (NASH), cirrhosis and death. However, currently there are no FDA approved therapies that treat NAFLD/NASH. Thrombospondin-I (TSP-1) is a large glycoprotein in the extracellular matrix that regulates numerous cellular pathways including transforming growth factor beta 1 (TGF-β1) activation, angiogenesis, inflammation and cellular adhesion. Increased expression of TSP-1 has been reported in various liver diseases; however, its role in NAFLD/NASH is not well understood. We first examined TSP-1 modulation in hepatic stellate cell activation, a critical initiating step in hepatic fibrosis. Knockdown or inhibition of TSP-1 attenuated HSC activation measured by alpha smooth muscle actin (α-SMA) and Collagen I expression. To investigate the impact of TSP-1 modulation in context of NAFLD/NASH, we examined the effect of TSP-1 deficiency in the choline deficient L-amino acid defined high fat diet (CDAHFD) model of NASH in mice by assessing total body and liver weight, serum liver enzyme levels, serum lipid levels, liver steatosis, liver fibrosis and liver gene expression in wild type (WT) and TSP-1 null mice. CDAHFD fed mice, regardless of genotype, developed phenotypes of NASH, including significant increase in liver weight and liver enzymes, steatosis and fibrosis. However, in comparison to WT, CDAHFD-fed TSP-1 deficient mice were protected against numerous NASH phenotypes. TSP-1 null mice exhibited a decrease in serum lipid levels, inflammation markers and hepatic fibrosis. RNA-seq based transcriptomic profiles from the liver of CDAHFD fed mice determined that both WT and TSP-1 null mice exhibited similar gene expression signatures following CDAHFD, similar to biophysical and histological assessment comparison. Comparison of transcriptomic profiles based on genotype suggested that peroxisome proliferator activated receptor alpha (PPARα) pathway and amino acid metabolism pathways are differentially expressed in TSP-1 null mice. Activation of PPARα pathway was supported by observed decrease in serum lipid levels. Our findings provide important insights into the role of TSP-1 in context of NAFLD/NASH and TSP-1 may be a target of interest to develop anti-fibrotic therapeutics for NAFLD/NASH.
Project description:Nonalcoholic fatty liver disease (NAFLD) is a global epidemic that is likely to become the most common cause of chronic liver disease in the next decade, worldwide. Though numerous drugs have been evaluated in clinical trials, most of them have returned inconclusive results and shown poorly-tolerated adverse effects. None of the drugs have been approved by the Food and Drug Administration for treating biopsy-proven non-alcoholic steatohepatitis (NASH). Vitamin E and pioglitazone have been extensively used in treatment of biopsy-proven nondiabetic NASH patients. Although some amelioration of inflammation has been seen, these drugs did not improve the fibrosis component of NASH. Therefore, dietary modification and weight reduction have remained the cornerstone of treatment of NASH; moreover, they have shown to improve histological activity as well as fibrosis. The search for an ideal drug or 'Holy Grail' within this landscape of possible agents continues, as weight reduction is achieved only in less than 10% of patients. In this current review, we summarize the drugs for NASH which are under investigation, and we provide a critical analysis of their up-to-date results and outcomes.