NKG2D-mediated immunosensing of metabolically stressed hepatocytes by innate-like T cells is essential for initiation of NASH and fibrosis
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ABSTRACT:
PROVIDER: PRJNA824801 | ENA |
REPOSITORIES: ENA
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Project description:Metabolic-associated fatty liver disease (MAFLD) comprises a spectrum of clinical entries ranging from benign steatosis to cirrhosis. A key event in the pathophysiology of MAFLD is the development of non-alcoholic steatohepatitis (NASH) that may lead to fibrosis and hepatocellular carcinoma. What triggers inflammation in MAFLD is unknown. We find that lipid accumulation in hepatocytes induces expression of ligands for the activating immune receptor NKG2D. Tissue-resident innate-like T cells are activated through NKG2D and secrete IL-17A. IL-17A licenses hepatocytes to produce chemokines that recruit pro-inflammatory cells into the liver, causing NASH and fibrosis. NKG2D-deficient mice did not develop fibrosis in a dietary model for NASH and had a marked decrease in the incidence of hepatic tumors. Importantly, the frequency of IL-17A+ γδ T cells in the blood MAFLD patients correlated with liver pathology. Our findings identify a key molecular mechanism through which stressed hepatocytes trigger inflammation in context of MAFLD.
2022-04-11 | GSE200482 | GEO
Project description:BACKGROUND & AIMS: Recent studies revealed that hemoglobin is expressed in some non-erythrocytes and it suppresses oxidative stress when overexpressed. Oxidative stress plays a critical role in the pathogenesis of non-alcoholic steatohepatitis (NASH). This study was to investigate whether hemoglobin is expressed in hepatocytes and how it is related to oxidative stress in NASH patients. METHODS: Microarray was performed to identify differentially expressed genes in NASH. Quantitative real time PCR (qRT-PCR) was used to examine gene expression levels. Western blotting and immunofluorescence staining were employed to examine hemoglobin proteins. Flow cytometry was used to measure intracellular oxidative stress. RESULTS: Analysis of microarray gene expression data has revealed a significant increase in the expression of hemoglobin alpha (HBA1) and beta (HBB) in liver biopspies from NASH patients. Increased hemoglobin expression in NASH was validated by qRT-PCR. However, the expression of erythrocyte specific marker genes such as SPTA, SPTB, GYPA, GATA1, and ALAS2 did not change, indicating that increased hemoglobin expression in NASH was not from erythropoiesis, but could result from increased expression in hepatocytes. Immunofluorescence staining demonstrated positive HBA1 and HBB expression in the hepatocytes of NASH livers. Hemoglobin expression was also observed in human hepatocellular carcinoma HepG2 cell line. Furthermore, treatment with hydrogen peroxide, a known oxidative stress inducer, induced a dose dependent increase in HBA1 expression in HepG2 cells. Intriguingly, forced hemoglobin expression suppressed oxidative stress. CONCLUSIONS: Oxidative stress upregulates hemoglobin expression in hepatocytes. Suppression of oxidative stress by hemoglobin could be a mechanism to protect hepatocytes from oxidative damage. These findings suggest that hemoglobin is an inducible antioxidant in hepatocytes in response to increased oxidative stress as found in NASH livers. Twelve biopsy diagnosed NASH patients were included in this study. For control groups, total RNA from 5 different subjects were purchased from ADMET. These subjects are free from liver disease.
2010-10-20 | E-GEOD-24807 | biostudies-arrayexpress
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.
2013-04-02 | E-GEOD-37031 | biostudies-arrayexpress
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
2011-07-12 | E-MEXP-3291 | biostudies-arrayexpress
Project description:BACKGROUND & AIMS: Recent studies revealed that hemoglobin is expressed in some non-erythrocytes and it suppresses oxidative stress when overexpressed. Oxidative stress plays a critical role in the pathogenesis of non-alcoholic steatohepatitis (NASH). This study was to investigate whether hemoglobin is expressed in hepatocytes and how it is related to oxidative stress in NASH patients. METHODS: Microarray was performed to identify differentially expressed genes in NASH. Quantitative real time PCR (qRT-PCR) was used to examine gene expression levels. Western blotting and immunofluorescence staining were employed to examine hemoglobin proteins. Flow cytometry was used to measure intracellular oxidative stress. RESULTS: Analysis of microarray gene expression data has revealed a significant increase in the expression of hemoglobin alpha (HBA1) and beta (HBB) in liver biopspies from NASH patients. Increased hemoglobin expression in NASH was validated by qRT-PCR. However, the expression of erythrocyte specific marker genes such as SPTA, SPTB, GYPA, GATA1, and ALAS2 did not change, indicating that increased hemoglobin expression in NASH was not from erythropoiesis, but could result from increased expression in hepatocytes. Immunofluorescence staining demonstrated positive HBA1 and HBB expression in the hepatocytes of NASH livers. Hemoglobin expression was also observed in human hepatocellular carcinoma HepG2 cell line. Furthermore, treatment with hydrogen peroxide, a known oxidative stress inducer, induced a dose dependent increase in HBA1 expression in HepG2 cells. Intriguingly, forced hemoglobin expression suppressed oxidative stress. CONCLUSIONS: Oxidative stress upregulates hemoglobin expression in hepatocytes. Suppression of oxidative stress by hemoglobin could be a mechanism to protect hepatocytes from oxidative damage. These findings suggest that hemoglobin is an inducible antioxidant in hepatocytes in response to increased oxidative stress as found in NASH livers.
2010-10-21 | GSE24807 | GEO
Project description:Human genetic studies have identified several MARC1 variants as protective against non-alcoholic fatty liver diseases (NAFLD). The MARC1 variants are associated with reduced lipid profiles, liver enzymes, and liver-related mortality. However, the role of mitochondrial amidoxime reducing component 1 (mARC1), encoded by MARC1, in NAFLD is still unknown and the therapeutic potential of this target has never been developed. Given that mARC1 is mainly expressed in hepatocytes, we developed an N-acetylgalactosamine conjugated mouse mARC1 siRNA to address this. In ob/ob mice, knockdown of mARC1 in mouse hepatocytes resulted in decreased liver weight, serum lipid enzymes, low-density lipoprotein cholesterol, and liver triglycerides. Loss of mARC1 also improved the lipid profiles and attenuated liver pathological changes in two diet-induced nonalcoholic steatohepatitis (NASH) mouse models. A comprehensive analysis of mARC1-deficient liver in NASH by metabolomics, proteomics, and lipidomics showed that mARC1 knockdown partially restored metabolites and lipids altered by diets. Taken together, loss of mARC1 protects mouse liver from NASH, suggesting a potential therapeutic approach of NASH by downregulation of mARC1 in hepatocytes.
2023-04-28 | MSV000091820 | MassIVE
Project description:Current therapeutic strategies for treating non-alcoholic steatohepatitis (NASH) have failed to alleviate liver fibrosis, which is a devastating feature leading to hepatic dysfunction. Here, we integrated single-nucleus transcriptomics and epigenomics to characterize all major liver cell types during NASH development in mice and humans. The bifurcation of hepatocyte trajectory with NASH progression was conserved between mouse and human. At the non-alcoholic fatty liver (NAFL) stage, hepatocytes exhibited metabolic adaptation, whereas at the NASH stage, a subset of hepatocytes was enriched for the signatures of cell adhesion and migration, which was mainly demarcated by receptor tyrosine kinase EphB2. EphB2, acting as a downstream effector of Notch signaling in hepatocytes, was sufficient to induce cell-autonomously inflammation. Knockdown of Ephb2 in hepatocytes ameliorated inflammation and fibrosis in NASH. Thus, EphB2 expressing hepatocytes contribute to NASH progression and may serve as a potential therapeutic target.
2023-02-08 | GSE189600 | GEO
Project description:Nonalcoholic steatohepatitis (NASH) is a progressive liver disease that is characterized by liver injury, inflammation and fibrosis. NASH pathogenesis is linked to reprogramming of chromatin landscape in the liver that predisposes hepatocytes to stress-induced tissue injury. However, the molecular nature of the putative checkpoint that maintains chromatin architecture and preserves hepatocyte health remains elusive. Here we show that heterogeneous nuclear ribonucleoprotein U (hnRNPU), a nuclear matrix protein that governs chromatin architecture and gene transcription, is a critical factor that couples chromatin disruption to NASH pathogenesis. RNA-seq and ChIP-seq studies revealed an extensive overlap between hnRNPU occupancy and altered gene expression during NASH. Hepatocyte-specific inactivation of hnRNPU disrupted liver chromatin accessibility, activated the molecular signature of NASH and sensitized mice to diet-induced NASH pathogenesis. Mechanistically, hnRNPU deficiency stimulated the expression of a truncated isoform of TrkB that promotes inflammatory signaling in hepatocytes and stress-induced cell death. These findings illustrate a novel mechanism through which disruptions of chromatin architecture drive the emergence of disease-specific signaling patterns that promote liver injury and exacerbate NASH pathogenesis.
2019-09-10 | GSE131336 | GEO
Project description:The liver is undergoing major rearrangements during the development of non-alcoholic steatohepatitis (NASH), from steatosis to severe lipid accumulation, inflammation and fibrosis. The mechanisms for this transition and the molecular changes preceding NASH are not fully understood. Here, we perform a single-cell RNA sequencing survey of 13,240 mouse liver cells during the development of non-alcoholic fatty liver disease. By measuring the entire transcriptome on a single-cell level from mice in the early stages of NASH development, we recognize known hepatocyte cell populations, Kupffer cells and stellate cells, as well as distinct gene expression changes in hepatocytes. We also reveal high hepatocyte heterogeneity in steatosis markers which projects a lipogenic trajectory of known and novel steatosis-associated genes. Importantly, we uncover distinct clusters of hepatocytes characterized by high or low Srebp1c expression with unique molecular signatures of lipogenesis. These results identify a novel regulatory pathway for lipogenesis in the liver that contributes to NASH progression.
2022-08-06 | GSE210501 | GEO
Project description:Nonalcoholic fatty liver disease (NAFLD) ranges from steatosis to nonalcoholic steatohepatitis (NASH), that often progresses to hepatocellular carcinoma (HCC) through a largely undefined mechanism. NASH and HCC both depend on inflammatory signaling whose master regulator is the NFκB transcription factor family, activated by canonical and non-canonical pathways. Here, we investigated non-canonical NFκB-inducing kinase (NIK/MAP3K14) in metabolic NASH, NASH to HCC transition as well as in DEN-induced HCC. We revealed that hepatocyte-specific NIK deficiency (NIKLKO) ameliorated metabolic NASH complications and reduced hepatocarcinogenesis however, independent of its role in NFB pathway. Instead, hepatic NIK attenuated hepatoprotective JAK2/STAT5 signaling that is a prerequisite for NASH and NASH to HCC progression in mice and humans. Our data suggest NIK-mediated inhibitory JAK2 phosphorylation at serine 633 that might be amenable for future therapeutic interventions in patients.
2022-12-08 | GSE146049 | GEO