Contribution of CARD9-mediated signalling to wound healing in skin.

The inflammatory response after skin injury involves the secretion of a variety of cytokines and growth factors that are necessary for tissue repair. Caspase recruitment domain-containing protein 9 (CARD9) is an essential signalling adaptor molecule for NF-κB activation upon triggering through C-type lectin receptors (CLRs), which are expressed in macrophages and dendritic cells. However, the role of CARD9 in inflammatory responses at the wound site has not been elucidated. In this study, we analysed the role of CARD9 in the healing process of skin wounds. Wounds were created on the backs of wild-type (WT) C57BL/6 mice and CARD9 gene-disrupted (knockout [KO]) mice. We analysed per cent wound closure, and the wound tissues were harvested for analysis of leucocyte accumulation and cytokine and chemokine expressions. CARD9KO mice exhibited significant attenuation of wound closure compared with WT mice on days 5, 7 and 10 postwounding, which was associated with decreased macrophage accumulation and reduced TNF-α, IL-1β, CCL3 and CCL4 expressions. These results suggest that CARD9 may be involved in the wound-healing process through the regulation of macrophage-mediated inflammatory responses.