Mechanistic aspects of antifibrotic effects of honokiol in Con A-induced liver fibrosis in rats: Emphasis on TGF-beta/SMAD/MAPK signaling pathways

Aim Liver fibrosis represents a massive global health burden with limited therapeutic options. Thus, the need for curative options is evident. Thus, this study aimed to assess the potential antifibrotic effect of honokiol in Concanavalin A (Con A) induced immunological model of liver fibrosis as well the possible underlying molecular mechanisms. Methods: Male Sprague-Dawley rats were treated with either Con A (20 mg/kg, IV) and/or honokiol (10 mg/kg, orally) for 4 weeks. Hepatotoxicity indices were as well as histopathological evaluation was done. Hepatic fibrosis was assessed by measuring alpha smooth muscle actin (alpha-SMA) expression and collagen fibers deposition by Masson's trichrome stain and hydroxyproline content. To elucidate the underlying molecular mechanisms, the effect of honokiol on oxidative stress, inflammatory markers as well as transforming growth factor beta (TGF-beta)/SMAD and mitogen-activated protein kinase (MAPK) pathways was assessed. Key findings: Honokiol effectively reversed the hepatotoxicity indices elevations and abnormal histopathological changes induced by Con A. Besides, honokiol attenuated Con A-induced liver fibrosis by down-regulation of hydroxyproline levels, alpha-SMA expression together with a marked decrease in collagen fibers deposition. Mechanistically Con A induced oxidative stress, provocation of inflammatory responses and activation of TGF-beta/SMAD/MAPK pathways. Contrariwise, honokiol co-treatment significantly restored antioxidant defence mechanisms, down-regulated inflammatory cascades and inhibited TGF-beta/SMAD/MAPK signaling pathways. Conclusion: The results provide an evidence for the promising antifibrotic effect of honokiol that could be partially due to suppressing oxidative stress and inflammatory processes as well as inhibition of TGF-beta/SMAD/MAPK signaling pathways.