Bacillus subtilis WB800N alleviates diabetic wounds in mice by regulating gut microbiota homeostasis and TLR2

This study aims to investigate the effect of Bacillus subtilis WB800N on diabetic wounds.Haematoxylin & eosin (H&E) staining was used to observe the healing of skin wounds. Collagen deposition was assessed by Masson staining. Western blotting and qRT-PCR were used to detect vascular endothelial-related factors (VWF), CD31, TLR2, NLRP3, ASC and Caspase-1 expression. 16S rDNA sequencing detected microbiota distribution. The concentrations of IL-1β and IL-37 were measured by ELISA. Apoptosis was measured by the TUNEL assay.Compared with the control group, wound healing was delayed in diabetic mice. The wound area in the Bacillus subtilis group decreased more significantly than the diabetic wound group. H&E staining showed that Bacillus subtilis WB800N promoted wound healing and increased re-epithelialization. Masson staining showed that Bacillus subtilis WB800N increased collagen deposition in mice with diabetic wounds. Bacillus subtilis WB800N upregulated VWF and CD31 protein expression in diabetic wounds mice. The 16S rDNA results showed that Bacillus subtilis WB800N reduced the diversity of the gut microbiota of diabetic wounds mice and regulated the microbial composition. At the genus level, Bacillus subtilis WB800N reduced the relative abundance of Muribaculaceae and CG - 005 in diabetic wounds mice, whilst increasing the relative abundance of Lactobacillus. Bacillus subtilis WB800N increased the expression of TLR2, NLRP3, ASC and Caspase-1. Bacillus subtilis WB800N increased the concentrations of IL-1β and IL-37 in serum. Bacillus subtilis WB800N upregulated cell apoptosis. The TLR2 antagonist Sparstolonin B (SsnB) reduced the expression of TLR2, NLRP3, ASC, Caspase-1, IL-1β and IL-37 and the apoptosis in diabetic wounds mice, whilst the combined intervention of Bacillus subtilis and SsnB reversed the effect of SsnB treatment alone.Bacillus subtilis WB800N alleviated diabetic wound healing by regulating gut microbiota homeostasis and TLR2.Our findings might provide potential therapeutic targets for diabetic wounds.