DHI exerts anti-fibrotic effects in BDL rats, LX-2 cells and rat pHSCs by inhibiting the YAP and TEAD2 complex and stimulating autophagy. These findings indicate that DHI may be a potential therapeutic for the treatment of liver fibrosis.

The inflammasome exacerbates cholestatic liver injury independent of the effects of bile acids. Blocking the inflammasome (presumably in macrophages) paradoxically increases fibrosis in cholestatic mouse liver by promoting an anti-inflammatory M2 phenotype. BACKGROUND & AIMS:Inflammation plays an important role in the pathogenesis of cholestatic liver injury, but it is unclear whether the inflammasome is involved and is the objective of this study. METHODS:Gene expression was analyzed in the livers of patients with primary biliary cholangitis (n ¼ 15) and primary sclerosing cholangitis (n ¼ 15). Bile duct ligation (BDL) or sham operation was performed in wild-type (WT) and Caspase-1 -/-(Casp1 -/-) mice for 7 days. Mouse hepatocytes and macrophages were treated with bile acids. RESULTS:Caspase-1, NLRP1, NLRP3 and IL-1b were significantly increased in the livers of cholestatic patients when compared to healthy control subjects (n ¼ 9). Significantly higher levels of plasma IL-1b (826 vs 345 pg/ml), ALT (674 vs 482 U/L) and ALP (900 vs 622 U/L) were seen in WT BDL mice compared to Casp1 -/-BDL mice. Caspase-1 cleavage was found only in WT BDL livers. Assessment of liver histology indicated more fibrosis in Casp1 -/-BDL mice than in WT BDL mice, confirmed by analyses of liver hydroxyproline content and the expression of fibrotic genes. Profiling of immune cells revealed that there were more macrophages in Casp1 -/-BDL livers than in WT BDL livers. Further macrophage phenotype characterization indicated that Casp1 -/-BDL livers had more M2 anti-inflammatory macrophages evidenced by more CD206 positive cells and higher expression of IL-4, CD163, Fizz1 and IL-33. When mouse hepatocytes and peritoneal macrophages were exposed to cholestatic levels of major endogenous bile acids (300mM TCA), neither IL-1b induction nor procaspase-1 cleavage were detected. CONCLUSIONS:The inflammasome exacerbates cholestatic liver injury, but bile acids do not directly activate the inflammasome. (Cell Mol Gastroenterol Hepatol 2020;9:679-688; https://doi.

Background and Purpose This study investigates the antifibrotic activities and potential mechanisms of costunolide (COS), a natural sesquiterpene compound. Experimental Approach Rats subjected to bile duct ligation and mice challenged with CCl4 were used to study the antifibrotic effects of COS in vivo. Mouse primary hepatic stellate cells (pHSCs) and human HSC line LX‐2 also served as an in vitro liver fibrosis models. The expression of fibrogenic genes and signaling proteins in the neurogenic locus notch homologue protein 3 (Notch3)–hairy/enhancer of split‐1 (HES1) pathway was examined using western blot and/or real‐time PCR. Notch3 degradation was analysed using immunofluorescence and coimmunoprecipitation. Key Results In animals, COS administration attenuated hepatic histopathological injury and collagen accumulation and reduced the expression of fibrogenic genes. COS time‐ and dose‐dependently suppressed the levels of fibrotic markers in LX‐2 cells and mouse pHSCs. Mechanistic studies showed COS destabilized Notch3 and subsequently inhibited the Notch3–HES1 pathway, thus inhibiting HSC activation. Furthermore, COS blocked the WW domain‐containing protein 2 (WWP2)/protein phosphatase 1G (PPM1G) interaction and enhanced the effect of WWP2 on Notch3 degradation. Conclusions and Implications COS exerted potent antifibrotic effects in vitro and in vivo by disrupting the WWP2/PPM1G complex, promoting Notch3 degradation and inhibiting the Notch3/HES1 pathway. This indicates that COS may be a potential therapeutic candidate for the treatment of liver fibrosis.

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