IL-33 promotes Staphylococcus aureus-infected wound healing in mice

Interleukin (IL)-33, a newly identified member of IL-1 family of cytokines, plays a crucial role in polarizing Th2-associated immune responses. Recently growing evidence indicates that IL-33 also represents an important mediator of mucosal healing and epithelial restoration. In this study, we investigated the effect of IL-33 on antimicrobial infection and wound healing using a Staphylococcus aureus-infected incision model in mice. Our findings showed that the expression of IL-33 mRNA and protein was promptly increased in cutaneous wound tissues when challenged by methicillin-resistant S. aureus (MRSA). At the same time, exogenous IL-33 administration profoundly inhibited MRSA colonization and accelerated cutaneous wound repair. IL-33 upregulation promoted the proliferation of neutrophils and CXCR2 expression, which is related to augmented neutrophil trafficking into infectious sites for bactericidal effect. In addition, the beneficial effect of IL-33 is also implicated in enhancement of collagen deposition and the expression of extracellular matrix (ECM)-associated genes such as fibronectin and collagen IIIa, which implies a potential effect of IL-33 on matrix synthesis and reepithelialization during the wound repair process. All together, these findings reveal that IL-33 plays an essential effect in maintenance of cutaneous homeostasis and improvement of infectious wound healing.