[The mechanism of GSK-3β/CREB signaling pathway regulating macrophage pyroptosis and participating in the occurrence and development of diabetic foot ulcer].

Objective To investigate the role and possible mechanism of glycogen synthase kinase-3 beta (GSK-3β)/cAMP response element binding protein (CREB) signaling pathway in regulating macrophage pyroptosis in the pathogenesis and development of diabetic foot ulcer (DFU). Methods Thirty rats were randomly divided into control group, DFU group and GSK-3β inhibited group, with 10 rats in each group. Fasting blood glucose (FBG) was detected by dynamic blood glucose detector. The wound healing of each group was observed and recorded. The histopathologic changes of the wound were detected by HE staining. The level of wound fibrosis was detected by Masson staining. The protein levels of GSK-3β, CREB, gasdermin E (GSDME) and nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) in wound tissue were detected by Western blotting. The co-expression of F4/80, GSDME and NLRP3 in wound tissue was detected by immunofluorescence staining. The serum levels of IL-1β and IL-18 were detected by ELISA. Results Compared with the control group, FBG in DFU group was increased. Compared with DFU group, FBG in GSK-3β inhibition group was decreased. The wound healing rate of rats in the inhibited GSK-3β group was higher than that in the DFU group from day 3 to day 14, and the difference was significant on day 14. Therefore, samples from day 14 were used in the follow-up experiment. Compared with the control group, the wound tissue of rats in DFU group was significantly damaged with collagen deposition defect, and the expressions of GSK-3β, CREB and apoptosis-related proteins GSDME and NLRP3 were increased, and the co-expressions of F4/80 and GSDME, F4/80 and NLRP3 were increased. Serum levels of IL-1β and IL-18 were increased. Compared with DFU group, most of the wound tissues of rats in GSK-3β group were healed. Collagen deposition at the fracture was increased. The expressions of GSK-3β, CREB and GSDME, NLRP3 were decreased. The expression levels of F4/80 and GSDME were reduced, along with a decrease in the co-expression of F4/80 and NLRP3. Additionally, there was a reduction in serum concentrations of IL-1β and IL-18. Conclusion GSK-3β/CREB signaling pathway and macrophage pyroptosis are significantly up-regulated in DFU rats. Inhibition of this pathway can promote DFU healing and down-regulate macrophage pyroptosis level.