Targeting antioxidant factor Nrf2 by raffinose ameliorates lipid dysmetabolism-induced pyroptosis, inflammation and fibrosis in NAFLD

Non-alcoholic fatty liver disease (NAFLD) is a persistent liver condition that affects both human health and animal productive efficiency on a global scale. A number of naturally occurring compounds activate nuclear factor erythroid 2-related factor 2 (Nrf2) as a transcription factor with important protective effects against many liver diseases, including NAFLD. Raffinose (Ra), an oligosaccharide extracted from several plants, exhibits diverse biological functions. However, the uncertainty lies in determining whether the activation of Nrf2 by Ra can provide a preventive effect on liver lipotoxicity. The aim of this study was to shed light on the molecular pathways by which Ra possesses its protective benefits against NAFLD. Experimental protocols were established using WT and Nrf2-null (Nrf2−/−) mice. Liver samples from each group were collected for Western blot, RT-qPCR, H & E, Sirius red and Oil red O staining. Additionally, serums were processed for ELISA. ALM12 cells were gathered for Western blot and immunofluorescence. Moreover, to elucidate the molecular mechanism of Ra, molecular docking was performed. Our results indicated that Ra remarkably alleviated liver lipotoxic in vivo and in vitro. Ra treatment effectively corrected hepatic steatosis, the release of AST, ALT, TG, and TC, as well as the depletion of HDL and LDL. Meanwhile, Ra efficiently prevented inflammation by inhibiting the TLR4-MyD88-NF-κB pathway and pyroptosis. Additionally, these findings implied that Ra reduced the production of fibrosis-related proteins, which enhanced collagen deposition. Molecular docking revealed that Ra possessed the ability to bind specific regions of Nrf2, resulting in the enhancement of Nrf2 activation and nuclear translocation. Ra treatment restored serum redox factors and antioxidant enzymes to normal levels; however, these alterations were clearly reversed in Nrf2−/− mice. This study reveals novel information on Ra's protective benefits against liver injury caused by abnormal lipid metabolism; these effects are mostly mediated by Nrf2 activation, suggesting a potential new medicine or treatment strategy for NAFLD.