Project description:Dysfunctional adipose tissue is believed to promote the development of hepatic steatosis and systemic insulin resistance, but many of the mechanisms involved are still unclear. Lipin 1 catalyzes the conversion of phosphatidic acid to diacylglycerol (DAG), the penultimate step of triglyceride synthesis, which is essential for lipid storage. Herein we found that adipose tissue LPIN1 expression is decreased in people with obesity compared to lean subjects and low LPIN1 expression correlated with multi-tissue insulin resistance and increased rates of hepatic de novo lipogenesis. Comprehensive metabolic and multi-omic phenotyping demonstrated that adipocyte-specific Lpin1-/- mice had a metabolically-unhealthy phenotype, including liver and skeletal muscle insulin resistance, hepatic steatosis, increased hepatic de novo lipogenesis, and transcriptomic signatures of nonalcoholic steatohepatitis that was exacerbated by high-fat diets. We conclude that adipocyte lipin 1-mediated lipid storage is vital for preserving adipose tissue and systemic metabolic health and its loss predisposes mice to nonalcoholic steatohepatitis.
Project description:Nonalcoholic steatohepatitis (NASH) is a severe form of nonalcoholic fatty liver disease (NAFLD) that is characterized by hepatic steatosis, inflammation, hepatocellular injury, and fibrosis, which lead to progressed cirrhosis and hepatocellular carcinoma. Despite its increasing prevalence on a global scale, the pathogenesis of NASH progression is not well understood. To elucidate the underlying mechanisms of NASH progression, we conducted transcriptome analyses of Japanese NAFLD cohort in our facility.
Project description:Here, we found that microRNA-223 (miR-223) was highly elevated in hepatocytes after high fat diet (HFD) feeding in mice and in human nonalcoholic steatohepatitis (NASH) samples. Genetic deletion of the miR-223 induced a full spectrum of nonalcoholic fatty liver disease (NAFLD) in mice after long-term (up to one year) HFD feeding including NASH-related steatosis, inflammation, fibrosis and HCC. To better explore the mechanisms underlying the abnormalities observed in HFD-fed miR-223KO mice, we examined hepatic gene expression in 3-month-HFD-fed WT and miR-223KO mice by microarray analysis. Finally, we revealed that miR-223 plays a key role in controlling steatosis-to-NASH progression by inhibiting hepatic Cxcl10 and Taz expression.
Project description:The current study was designed to determine if dietary fatty acid concentration and composition affects the development and progression of nonalcoholic fatty liver disease. Male SD rats were overfed diets low (5%) or high (70%) fat diets via total enteral nutrition where the fat source was olive oil (monounsaturated), or corn oil (polyunsaturated). Overfeeding 5% corn oil produced little steatosis relative to feeding 5% olive oil. This was associated with lower fatty acid synthesis and reduced SREBP-c signaling in the 5% corn oil group. Overfeeding 70% fat diets increased steatosis and lead to increased liver necrosis in the 70% corn oil but not olive oil group. Increased injury after feeding polyunsaturated fat diets was linked to peroxidizability of hepatic free fatty acids and triglycerides and appearance of peroxidaized lipid products HETES and HODES previously linked to clinical nonalcoholic steatohepatitis. Male SD rats were overfed diets low (5%) or high (70%) fat diets via total enteral nutrition where the fat source was olive oil (monounsaturated) or corn oil (polyunsaturated).
Project description:Liver is an important organ for fat metabolism. Excessive intake of a high-fat/energy diet is a major cause of hepatic steatosis and its complications such as nonalcoholic fatty liver disease and nonalcoholic steatohepatitis. Supplementation with lycopene, a natural compound, is effective in lowering triglyceride levels in the liver, although the underlying mechanism at the translational level is unclear. In this study, mice were fed a high-fat diet (HFD) to induce hepatic steatosis and treated with or without lycopene. Translation omics and transcriptome sequencing were performed on the liver to explore the regulatory mechanism of lycopene in liver steatosis induced by HFD, and identify differentially expressed genes (DEGs).
Project description:The progression from steatosis to nonalcoholic steatohepatitis (NASH) in nonalcoholic fatty liver disease (NAFLD) patients is one of the major causes of liver-related death worldwide and have limited effective therapies. We comparing the circular RNomics of liver fibroblasts isolated from patients with NAFLD-caused cirrhosis and the ones without NAFLD.
Project description:Objective: Nonalcoholic fatty liver disease (NAFLD) is linked to obesity and diabetes, suggesting an important role of adipose tissue in the pathogenesis of NAFLD. Here we aim to investigate the interaction between adipose tissue and liver in NAFLD, and identify potential early plasma markers that predict NASH. Research Design and Methods: C57Bl/6 mice were chronically fed a high fat diet to induce NAFLD and compared with mice fed low fat diet. Extensive histological and phenotypical analyses coupled with a time-course study of plasma proteins using multiplex assay was performed. Results: Mice exhibited pronounced heterogeneity in liver histological scoring, leading to classification into 4 subgroups: LF-low (LFL) responders displaying normal liver morphology, LF-high (LFH) responders showing benign hepatic steatosis, HF-low (HFL) responders displaying pre-NASH with macrovesicular lipid droplets, and HF-high (HFH) responders exhibiting overt NASH characterized by ballooning of hepatocytes, presence of Mallory bodies, and activated inflammatory cells. Compared to HFL responders, HFH mice gained weight more rapidly and exhibited adipose tissue dysfunction characterized by decreased final fat mass, enhanced macrophage infiltration and inflammation, and adipose tissue remodelling. Plasma haptoglobin, IL-1β, TIMP-1, adiponectin and leptin were significantly changed in HFH mice. Multivariate analysis indicated that in addition to leptin, plasma CRP, haptoglobin, eotaxin and MIP-1α early in the intervention were positively associated with liver triglycerides. Intermediate prognostic markers of liver triglycerides included IL-18, IL-1β, MIP-1γ and MIP-2, whereas insulin, TIMP-1, GCP-2 and MPO emerged as late markers. Conclusions: Our data support the existence of a tight relationship between adipose tissue dysfunction and NASH pathogenesis and point to several novel potential predictive biomarkers for NASH. Keywords: Expression profiling by array Male wildtype C57Bl/6 mice were fed LFD or HFD for 21 weeks. Mice were divided into 4 groups based on liver histology.
Project description:BCAA were administered to atherogenic and high-fat (Ath & HF) diet-induced nonalcoholic steatohepatitis (NASH) model mice and platelet-derived growth factor C transgenic mice (Pdgf-c Tg). Liver histology, tumor incidence, and gene expression profiles were evaluated. BCAA supplementation improved hepatic steatosis, inflammation, fibrosis, and tumors in the NASH mouse model, possibly through the modification of mTORC1 signaling.
Project description:Adipose tissue dysfunction is closely associated with the development and progression of nonalcoholic fatty liver disease (NAFLD). Recent studies have implied an important role of prohibitin-1 (PHB1) in adipose tissue function. In the current study, we aimed to explore the function of adipocyte PHB1 in the development and progression of NAFLD. The PHB1 protein levels in adipose tissues were markedly decreased in mice fed a high-fat diet (HFD) compared to those fed a chow diet. To explore the function of adipocyte PHB1 in the progression of NAFLD, mice with adipocyte-specific (adipo) deletion of Phb1 (Phb1adipo-/- mice) were generated. Notably, Phb1adipo-/- mice did not develop obesity but displayed severe liver steatosis under HFD feeding. Compared to HFD-fed wild-type (WT) mice, HFD-fed Phb1adipo-/- mice displayed dramatically lower fat mass with significantly decreased levels of total adipose tissue inflammation, including macrophage and neutrophil number as well as the expression of inflammatory mediators. To our surprise, although liver steatosis in Phb1adipo-/- mice was much more severe, liver inflammation and fibrosis were similar to WT mice after HFD feeding. RNA sequencing analyses revealed that the interferon pathway was markedly suppressed while the bone morphogenetic protein 2 pathway was significantly up-regulated in the liver of HFD-fed Phb1adipo-/- mice compared with HFD-fed WT mice. Conclusion: HFD-fed Phb1adipo-/- mice display a subtype of the lean NAFLD phenotype with severe hepatic steatosis despite low adipose mass. This subtype of the lean NAFLD phenotype has similar inflammation and fibrosis as obese NAFLD in HFD-fed WT mice; this is partially due to reduced total adipose tissue inflammation and the hepatic interferon pathway.
Project description:The current study was designed to determine if dietary fatty acid concentration and composition affects the development and progression of nonalcoholic fatty liver disease. Male SD rats were overfed diets low (5%) or high (70%) fat diets via total enteral nutrition where the fat source was olive oil (monounsaturated), or corn oil (polyunsaturated). Overfeeding 5% corn oil produced little steatosis relative to feeding 5% olive oil. This was associated with lower fatty acid synthesis and reduced SREBP-c signaling in the 5% corn oil group. Overfeeding 70% fat diets increased steatosis and lead to increased liver necrosis in the 70% corn oil but not olive oil group. Increased injury after feeding polyunsaturated fat diets was linked to peroxidizability of hepatic free fatty acids and triglycerides and appearance of peroxidaized lipid products HETES and HODES previously linked to clinical nonalcoholic steatohepatitis.