Hypercalin B alleviates nonalcoholic steatohepatitis progression via suppressing mTORC1 signaling pathway / 药学学报

ABSTRACT

The global incidence rate of nonalcoholic steatohepatitis (NASH) continues to rise. The pathogenesis of NASH is complex, and there is no effective clinical treatment. Previous study has shown that DEAD box protein 5 (DDX5) can significantly alleviate the NASH process in mice. This study screened the natural product library of the research group and found that the active compound hypercalin B (HB) in Hypericum beanii N. Robson, a traditional Chinese medicine, can upregulate the expression of DDX5 protein in a dose-dependent manner. In this study, an in vitro model of NASH stimulated by palmitic acid (PA) and an animal model of NASH induced by the methionine- and choline-deficient diet (MCD) were constructed. Different concentrations of HB were used to investigate the effect and mechanism of HB in alleviating NASH progression. All animal experiments in this paper were approved by the Ethics Committee of China Pharmaceutical University (NO 2021-02-003). In vitro model results showed that HB significantly reduced the intracellular lipid deposition induced by free fatty acid (FFA). Animal experiments showed that HB improved liver injury by significantly reducing lipid accumulation in the liver of NASH mice, and reducing serum aspartate transaminase (AST) and alanine transaminase (ALT) levels. Moreover, HB could inhibit liver inflammation by reducing the mRNA levels of liver pro-inflammatory cytokines including interleukin 6 (IL-6), interleukin 1β (IL-1β), and tumor necrosis factor α (TNFα). Further research showed that HB could reduce the phosphorylation level of the mechanical target of rapamycin (mTOR) and reduce the expression of sterol regulatory element binding protein 1 (SREBP1) and fatty acid synthase (FASN), thereby improving lipid metabolism and alleviating NASH progression, and the effects of HB against NASH were dependent on DDX5. In conclusion, HB can improve lipid metabolism and inhibit inflammatory activation by suppressing mTORC1 pathway via upregulating DDX5 protein, and showed promising anti-NASH activity in vitro and in vivo.