Sclareol attenuates liver fibrosis through SENP1-mediated VEGFR2 SUMOylation and inhibition of downstream STAT3 signaling.

Liver fibrosis is a key global health care burden. Sclareol, isolated from Salvia sclarea, possesses various biological activities. Its effect on liver fibrosis remains unknown. This study was proposed to evaluate the antifibrotic activity of sclareol (SCL) and explore its underlying mechanisms. Stimulated hepatic stellate cells served as an in vitro liver fibrosis model. The expression of fibrotic markers was assessed by western blot and real-time PCR. Two classical animal models, bile duct-ligated rats and carbon tetrachloride-treated mice, were utilized for the in vivo experiments. The liver function and fibrosis degree were determined by serum biochemical and histopathological analyses. VEGFR2 SUMOylation was analyzed using coimmunoprecipitation assay. Our results indicated that SCL treatment restricted the profibrotic propensity of activated HSCs. In fibrotic rodents, SCL administration alleviated hepatic injury and reduced collagen accumulation. Mechanistic studies indicated that SCL downregulated the protein level of SENP1 and enhanced VEGFR2 SUMOylation in LX-2 cells, which affected its intracellular trafficking. Blockade of the interaction between VEGFR2 and STAT3 was observed, resulting in the suppression of downstream STAT3 phosphorylation. Our findings demonstrated that SCL has therapeutic efficacy against liver fibrosis through mediating VEGFR2 SUMOylation, suggesting that SCL may be a potential candidate compound for its treatment.

Dehydromevalonolactone ameliorates liver fibrosis and inflammation by repressing activation of NLRP3 inflammasome.

Liver fibrosis is an important process in chronic liver disease and is strongly related to poor prognosis. Dehydromevalonolactone (C8) is a natural product isolated from a fungus of Fusarium sp. CPCC 401218, and its pharmacological activity has never been reported before. In this study, the potential of C8 as an anti-hepatic fibrosis agent was investigated. In human hepatic stellate cell (HSC) line LX-2, C8 suppressed the increased expression of COL1A1 and α-SMA induced by TGFß1, which indicated that C8 could repress the activation of HSCs. In bile duct ligated rats, C8 administration (100 mg/kg, i.p.) markedly attenuated liver injury, fibrosis, and inflammation, and suppressed the expression of the macrophage surface marker F4/80. In terms of mechanism, C8 treatment blocked the activation of the NLRP3 inflammasome, which was stimulated by LPS and nigericin in bone marrow-derived macrophages (BMDMs) and companied by the release of active IL-1ß. In addition, the activation of LX-2 cells induced by IL-1ß released from BMDMs was also inhibited after C8 administration, which indicated that C8 repressed HSCs activation by inhibiting the activation of NLRP3 inflammasome in macrophages. Furthermore, C8 exhibited the effects of anti-fibrosis and inhibiting the expression of NLRP3 inflammasome in non-alcoholic steatohepatitis (NASH) mice. Finally, C8 can be commendably absorbed in vivo and was safe for mice at the concentration of 1000 mg/kg (p.o.). In summary, our study reveals that C8 ameliorates HSCs activation and liver fibrosis in cholestasis rats and NASH mice by inhibiting NLRP3 inflammasome in macrophages, and C8 might be a safe and effective candidate for the treatment of liver fibrosis.

Pantoprazole ameliorates liver fibrosis and suppresses hepatic stellate cell activation in bile duct ligation rats by promoting YAP degradation.

Liver fibrosis is one of the most severe pathologic consequences of chronic liver diseases, and effective therapeutic strategies are urgently needed. Proton pump inhibitors (PPIs) are H+/K+-ATPase inhibitors and currently used to treat acid-related diseases such as gastric ulcers, which have shown other therapeutic effects in addition to inhibiting acid secretion. However, few studies have focused on PPIs from the perspective of inhibiting hepatic fibrosis. In the present study, we investigated the effects of pantoprazole (PPZ), a PPI, against liver fibrosis in a bile duct ligation (BDL) rat model, human hepatic stellate cell (HSC) line LX-2 and mouse primary HSCs (pHSCs), and explored the potential mechanisms underlying the effects of PPZ in vitro and in vivo. In BDL rats, administration of PPZ (150 mg· kg-1· d-1, i.p. for 14 d) significantly attenuated liver histopathological injury, collagen accumulation, and inflammatory responses, and suppressed fibrogenesis-associated gene expression including Col1a1, Acta2, Tgfß1, and Mmp-2. In LX-2 cells and mouse pHSCs, PPZ (100-300 µM) dose-dependently suppressed the levels of fibrogenic markers. We conducted transcriptome analysis and subsequent validation in PPZ-treated LX-2 cells, and revealed that PPZ inhibited the expression of Yes-associated protein (YAP) and its downstream targets such as CTGF, ID1, survivin, CYR61, and GLI2. Using YAP overexpression and silencing, we demonstrated that PPZ downregulated hepatic fibrogenic gene expression via YAP. Furthermore, we showed that PPZ promoted the proteasome-dependent degradation and ubiquitination of YAP, thus inhibiting HSC activation. Additionally, we showed that PPZ destabilized YAP by disrupting the interaction between a deubiquitinating enzyme OTUB2 and YAP, and subsequently blocked the progression of hepatic fibrosis.

Costunolide represses hepatic fibrosis through WW domain-containing protein 2-mediated Notch3 degradation.

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.