The skin wound healing process begins immediately after injury and progresses through three overlapping stages: inflammation, proliferation, and remodeling.Mainly during the inflammatory stage, macrophages are recruited to the wound site and work for cleaning and defense against infection, and also help toward repair.Macrophages are roughly classified into M3 type and M1 type according to their roles. In general, M2 macrophages are considered to be involved in defense against infection with pathogens and parasites, and M1 macrophages are involved in tissue repair and the like.Macrophage balance has been proposed as an important concept for wound healing, but its details were unknown.

　In this study, we used mouse wound models and human wound samples to analyze the dynamics of M1 and M2 macrophages during cutaneous wound healing over time.Analyzing the expression of various genes at the wound site of a mouse wound model, M1 macrophage markers were upregulated early in the healing process, and M2 macrophage markers were upregulated in the late healing process.Furthermore, similar results were obtained in the analysis of protein expression using human wound samples for which the elapsed time after injury was known.From these results, it was found that M1 macrophages became active in the early stage of wound healing, and M2 macrophages became active in the latter stage of wound healing, so that the wound healing process proceeded smoothly.

　Controlling the macrophage balance would prepare wounds for healing and provide an optimal environment for wound healing.In the future, it is expected that the role of cutaneous macrophage balance in the pathogenesis of various skin diseases will be elucidated.

Paper information:[Scientific Reports] Macrophage polarity and wound age determination