Identification of chikusetsusaponin IVa as a novel lysine-specific demethylase 1 inhibitor that ameliorates high fat diet-induced MASLD in mice

Diet-induced metabolic dysfunction steatotic liver disease (MASLD) is also called as non-alcoholic fatty liver disease (NAFLD) with limited effective strategies available. We previously have shown that chikusetsusaponin IVa (CHS), a dietary saponin from herbs in South American known for their metabolic benefits, mitigates diet-induced diabetes. In this study we investigated the beneficial effects of CHS on MASLD and the underlying mechanisms. MAFLD mouse model was established by the high-fat diet (HFD) for 6 weeks and then were treated with CHS (50 mg·kg^-1·d^-1, i.g.) for another 8 weeks. By conducting transcriptomic analysis in palmitic acid-treated HepG2 cells and primary hepatocytes as well as lipidomic analysis in liver tissues, we demonstrated that HFD activated the intestinal farnesoid X receptor (FXR) pathway, leading to the release of FGF15/19, which in turn promoted hepatic FXR-SHP binding with cAMP-responsive element-binding protein H (CREBH), thereby inhibiting CREBH-mediated fatty acid oxidation (FAO) and ketogenesis. Intriguingly, we found that CHS improved lipid metabolism in HFD mice by suppressing the enterohepatic crosstalk of FXR-SHP to enhance CREBH transactivation. Among these, lysine-specific demethylase 1 (LSD1)-mediated histone demethylation played a crucial role in lipid metabolic reprogramming. Moreover, we identified LSD1 as a critical cellular target of CHS, directly binding to Lys661 and Tyr761 of LSD1 to inhibit its histone demethylation activity. Our results suggest that targeting intestinal LSD1 with CHS could be a promising strategy for MAFLD treatment, offering new insights into the bioavailability and efficacy of natural products.