G protein-coupled receptor 35 attenuates nonalcoholic steatohepatitis by reprogramming cholesterol homeostasis in hepatocytes

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. Fat accumulation "sensitizes" the liver to insult and leads to nonalcoholic steatohepatitis (NASH). G protein-coupled receptor 35 (GPR35) is involved in metabolic stresses, but its role in NAFLD is unknown. We report that hepatocyte GPR35 mitigates NASH by regulating hepatic cholesterol homeostasis. Specifically, we found that GPR35 overexpression in hepatocytes protected against high-fat/cholesterol/fructose (HFCF) diet-induced steatohepatitis, whereas loss of GPR35 had the opposite effect. Administration of the GPR35 agonist kynurenic acid (Kyna) suppressed HFCF diet-induced steatohepatitis in mice. Kyna/GPR35 induced expression of StAR-related lipid transfer protein 4 (STARD4) through the ERK1/2 signaling pathway, ultimately resulting in hepatic cholesterol esterification and bile acid synthesis (BAS). The overexpression of STARD4 increased the expression of the BAS rate-limiting enzymes cytochrome P450 family 7 subfamily A member 1 (CYP7A1) and CYP8B1, promoting the conversion of cholesterol to bile acid. The protective effect induced by GPR35 overexpression in hepatocytes disappeared in hepatocyte STARD4-knockdown mice. STARD4 overexpression in hepatocytes reversed the aggravation of HFCF diet-induced steatohepatitis caused by the loss of GPR35 expression in hepatocytes in mice. Our findings indicate that the GPR35-STARD4 axis is a promising therapeutic target for NAFLD.

γδ T cells in liver diseases / 医学前沿

γδ T cells display unique developmental, distributional, and functional patterns and can rapidly respond to various insults and contribute to diverse diseases. Different subtypes of γδ T cells are produced in the thymus prior to their migration to peripheral tissues. γδ T cells are enriched in the liver and exhibit liver-specific features. Accumulating evidence reveals that γδ T cells play important roles in liver infection, non-alcoholic fatty liver disease, autoimmune hepatitis, liver fibrosis and cirrhosis, and liver cancer and regeneration. In this study, we review the properties of hepatic γδ T cells and summarize the roles of γδ T cells in liver diseases. We believe that determining the properties and functions of γδ T cells in liver diseases enhances our understanding of the pathogenesis of liver diseases and is useful for the design of novel γδ T cell-based therapeutic regimens for liver diseases.

Liver-targeted expression of chemokine CXCL10 inhibits ConA-induced liver injury / 中国免疫学杂志

Objective:To explore the effect and mechanism of CXCL10 on immune-mediated liver injury.Methods:The CXCL10 expression vector was injected into mice by hydrodynamic injection.The levels of CXCL10 in the liver were measured 72 hours after injection.Concanavalin A (ConA) was injected into mice to induce immune-mediated liver injury.The levels of alanine a minotransferase (ALT),tissue damage,IFN-γ,TNF-α and percentages and numbers of regulatory T cells were tested and compared between CXCL10 expression group and control group.Results:The levels of CXCL10 in the liver were significantly increased at 72 hours after CXCL10 expression vector was injected.The pretreatment of CXCL10 expression vector markedly reduced ConA-induced ALT levels,IFN-γlevels and TNF-α levels.Additionally,the pretreatment of CXCL10 expression vector increased the percentages and numbers of regulatory T ceils in the liver.Conclusion:The pretreatment of CXCL10 expression vector decreases the levels of inflammatory cytokines and attenuates ConA-induced liver injury,which might be beneficial for the treatment for immune-mediated liver injury.

Molecular mechanisms of NK cell development and diseases associated with functional compromise of NK cells / 中国免疫学杂志

Natural killer cells are the key effector cells in innate immune response,playing the role in pathogen clearance and tumor immunosurveillance by cytokine secretion and cytotoxicity.Hematopoietic stem cells go through developmental intermediates to generate mature NK cells under the progressive regulation of extrinsic factors and intrinsic factors.In the past thirty years, great progresses have been made in the developmental progress,niches,regulation of NK cells and the relationship between NK cells and dis-eases.In this review,we will discuss in detail the molecular mechanisms of NK cell development and the diseases caused by functional compromise of NK cells.