The Effect And Mechanism Of IL-33in Skin Wound Healing

Wound healing is the wound repair process by harmonizing action between a variety ofcells and molecules. The whole process can be divided into three stages of theinflammatory phase, the proliferative phase and modeling phase. Clinical practices mainlyuse method of local administration to promote faster wound healing, but for someinfections refractory wounds, the efficacy is often unsatisfactory. IL-33is apre-inflammatory cytokines, belongs to IL-1superfamily member, specifically binds itsreceptor ST2L, and ST2L receptor specifically expressed on the surface of a Th2lymphocytes in humans and rodents, it can induce Th2cellular immune response afterIL-33bind to ST2L, and consequently release IL-4, IL-5, IL-10and IL-13, which influencethe activity of epithelial cells, fibroblasts and macrophage. This study investigates the effectand mechanism of IL-33in the wound repair process by establishing two animal models ofnormal skin wound and Staphylococcus aureus (S. aureus)-infected skin wound.Objective:To prepare a large number of IL-33protein induced by IPTG, observe mouse skin injuryrepair, and investigate the mechanism of the wound repair process; also investigate the roleof IL-33in the process of wound repair after S. aureus-infected wound, which provides anew way for the clinical treatment of refractory wounds.Methods:To establish the mouse skin wound model, record mouse wound healing time andhealing rate after treatment with mIL-33; identify gene expression of cell growth factor byRT-PCR; observe local wound neovascularization, granulation tissue, the number of localfibroblasts and inflammatory cells, proliferation of collagen fibers and the generation of thealternative macrophage activation pathway (AAM) using tissue sections with HE staining,Masson staining and immunohistochemistry; investigate the effect of IL-33in themacrophage modulation of the fibroblast migration. Results:1. Optimal incubation time and the expression site of GST-IL-33fusion protein wereidentified. The recombinant bacterium was cultured2h at250rpm37℃, then added awork concentration of1mM IPTG and induced for another4h. After sonication,purification and enzyme digestion, IL-33protein was further purified.2. After treatment of BALB/c mice skin damage by the IL-33, the healing time of thecontrol group was10days, and the IL-33-treated group was8days. The wound healingtime was significantly shortened, greatly improved the healing rate, and the fibroblasts andcollagen of histopathology increased after treatment by IL-33. Compared with the controlgroup, IL-33treatment facilitated the expression levels of wound local AAM and themRNA of cell growth factor such as TGF-β, VEGF, and migration of fibroblasts.3. After treatment of C57BL/6mouse skin damage and infected S. aureus by IL-33, thehealing time of control group was12days, and the IL-33-treated group was10days. Theamount of fibroblasts and collagen fibers in IL-33-treated group were higher than thecontrol group. IL-33treatment upregulated the number of Th17-type cells at day5, theexpression levels of wound local AAM and the mRNA of cell growth factor such as TGF-β﹠VEGF.Conclusion:IL-33protein is successfully induced and prepared. Th2-type immune response can beinduced by treatment of skin wound with IL-33, which further accelerate skin wound repair.The effect of IL-33in wound healing may be related to regulation of the volume andfunction of inflammatory cell, migration of fibroblast, enhancement phagocytosis ability tobacteria and upregulation of AAM production.