Baicalein Reduces Pyroptosis of Acinar Cells in Hyperlipidemic Acute Pancreatitis by Inhibiting M1 Polarization of Macrophages via the HMGB1/TLR4/NLRP3 Pathway.

Abstract

Previous studies have shown that baicalein (BAI) can reduce pyroptosis of pancreatic acinar cells (PACs) in hyperlipidemic acute pancreatitis (HAP). This study aimed to elucidate the potential molecular mechanism of PAC pyroptosis mediated by BAI in HAP. A HAP rat model was established via a high-fat diet supplemented with 5% sodium taurocholate. Macrophages were treated with palmitic acid (PA). The rats and cells were treated with BAI. Molecular docking and DARTS assay were used to analyze BAI binding to HMGB1. Co-IP revealed that HMGB1 interacted with TLR4 and NLRP3 and that TLR4 interacted with NLRP3. The interaction between PA-induced macrophages and PACs was evaluated by cell coculture. BAI treatment improved pancreatic lesions, reduced iNOS expression, and decreased the number of M1 macrophages in HAP rats. BAI decreased CD86, HMGB1, NLRP3, ASC, cleaved caspase-1, and GSDMD-N expression in pancreatic tissue and serum IL-1β and IL-18 levels in HAP rats. Molecular docking results and DARTS assays revealed that BAI combined with HMGB1. Co-IP verified that HMGB1 interacted with TLR4 and NLRP3 and that TLR4 interacted with NLRP3. BAI and the HMGB1 inhibitor EP inhibited HMGB1, TLR4, and NLRP3 levels in PA-induced macrophages, increased cell viability, reduced pyroptosis, and ROS release, and inhibited M1 polarization. BAI and EP inhibited PA-induced M1 macrophage polarization and reduced PAC pyroptosis. HMGB1 overexpression partially reversed the effects of BAI on PA-treated macrophages and PACs. Under EP treatment, BAI had no significant effect on the above functions in PA-induced macrophages and PACs. BAI inhibited PA-induced macrophage M1 polarization through the HMGB1/TLR4/NLRP3 pathway, further inhibiting PAC pyroptosis. Our findings provide a theoretical and experimental basis for the molecular mechanism underlying BAI in the treatment of HAP.