Project description:Nonalcoholic steatohepatitis (NASH) might soon become the leading cause of end-stage liver disease worldwide with limited treatment options. Liver fibrosis, driven by chronic inflammation and hepatic stellate cells (HSCs) activation, critically determines morbidity and mortality in patients with NASH. Pyruvate kinase M2 (PKM2) is involved in immune activation and inflammatory liver diseases; however, its role and therapeutic potential in NASH fibrosis remain largely unexplored. By bioinformatic screening and analysis of human and murine NASH livers, we found that PKM2 was specifically upregulated in non-parenchymal cells (NPCs) in fibrotic NASH livers, especially in macrophages. Macrophage-specific Pkm2 knockout (Pkm2fl/flLysMCre) significantly ameliorated hepatic inflammation and fibrosis severity in three distinct NASH models induced by methionine–choline-deficient (MCD) diet, high-fat high-cholesterol (HFHC) diet and western diet plus weekly carbon tetrachloride injection (WD/CCl4). Single-cell transcriptomic analysis indicated that deletion of PKM2 in macrophage reduced profibrotic Ly6Chigh macrophage infiltration. Mechanistically, PKM2-dependent glycolysis promotes NLRP3 activation in proinflammatory macrophages, thus inducing HSCs activation and fibrogenesis. Pharmacological PKM2 agonist efficiently attenuated the profibrotic crosstalk between macrophages and HSCs in vitro and in vivo. Translationally, ablation of PKM2 in NPCs by cholesterol-conjugated heteroduplex oligonucleotides, a novel oligonucleotide drug that preferentially accumulated in the liver, dose-dependently reversed NASH fibrosis without observable hepatotoxicity. Our study highlights the pivotal role of macrophage PKM2 in advancing NASH fibrogenesis. Therapeutic modulation of PKM2 in a macrophage-specific or liver-specific fashion may serve as a novel strategy to combat NASH fibrosis.
Project description:Macrophages are a heterogeneous population of immune cells that play central roles in a broad range of biological processes, including the resolution of inflammation. Although diverse macrophage subpopulations have been identified, the characterization and functional specialization of certain macrophage subsets in inflamed tissues remain unclear. Here we uncovered a key role of specific macrophage subsets in tissue repair using proteomics, bioinformatics and functional analyses. We isolated two hepatic monocyte-derived macrophage subpopulations: Ly6ChiCX3CR1lo macrophages and Ly6CloCX3CR1hi macrophages during distinct phases of acute liver injury and employed label-free proteomics approach to profile the proteome of these cells. We found that the wound healing- and endocytosis-related proteins were specifically enriched in Ly6CloCX3CR1hi macrophages. Intriguingly, 12/15-lipoxygenase (Alox15), the most strongly up-regulated protein in Ly6CloCX3CR1hi macrophages, was identified as a specific marker for these macrophages. In co-culture systems, Ly6CloCX3CR1hi macrophages specifically induced hepatocyte proliferation. Furthermore, selective depletion of this population in CD11b-diphtheria toxin receptor mice significantly delayed liver repair. Overall, our studies shed light on the functional specialization of distinct macrophage subsets in the resolution of inflammation.
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:Lipid accumulation associated with immune cell infiltration leading to hepatocellular ballooning and lobular inflammation are the cardinal features of NASH. With onset and development of multi-omics approaches in the last decade, we have been able to comprehend the existence and functionality of gut microbial ecology. Apart from the compositional variation (dysbiosis), functional alteration of the microbial population i.e., the impact of the crosstalk between gut microbiota-derived metabolites with host cells also remains elusive in terms of regulation of immunometabolic homeostasis and overall human health and disease. Sodium butyrate (NaBu), a short chain fatty acid derived metabolite is known to modulate the inflammatory status of NASH pathogenesis; however, its mechanism of action is not clearly deciphered. To unveil the immunomodulatory activity of NaBu, we found robust anti-inflammatory effect of NaBu in diet induced NASH model with reduced macrophage infiltration. Mechanistically, independent of p65 nuclear translocation, by maintaining the enhanced acetylation status of p65 along with differential p65 recruitment to the proinflammatory gene promoter, NaBu suppressed the inflammatory milieu and resulted in better prognosis. Along with transcriptional rewiring, NaBu also altered the metabolic status, modified the functional outcome and exhibited differential secretome which ultimately resulted skewing of macrophages towards a prohealing phenotype and induced autocrine as well as paracrine death of proinflammatory macrophages to abrogate inflammation in both isolated LMs and in vivo model.
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.