Macrophage-Specific, Mafb-Deficient Mice Showed Delayed Skin Wound Healing

Macrophages play essential roles throughout the wound repair process. Nevertheless, mechanisms regulating the process are poorly understood. MAFB is specifically expressed in the macrophages in hematopoietic tissue and is vital to homeostatic function. Comparison of the skin wound repair rates in macrophage-specific, MAFB-deficient mice (Mafb^f/f::LysM-Cre) and control mice (Mafb^f/f) showed that wound healing was significantly delayed in the former. For wounded GFP knock-in mice with GFP inserts in the Mafb locus, flow cytometry revealed that their GFP-positive cells expressed macrophage markers. Thus, macrophages express Mafb at wound sites. Immunohistochemical (IHC) staining, proteome analysis, and RT-qPCR of the wound tissue showed relative downregulation of Arg1, Ccl12, and Ccl2 in Mafb^f/f::LysM-Cre mice. The aforementioned genes were also downregulated in the bone marrow-derived, M2-type macrophages of Mafb^f/f::LysM-Cre mice. Published single-cell RNA-Seq analyses showed that Arg1, Ccl2, Ccl12, and Il-10 were expressed in distinct populations of MAFB-expressing cells. Hence, the MAFB-expressing macrophage population is heterogeneous. MAFB plays the vital role of regulating multiple genes implicated in wound healing, which suggests that MAFB is a potential therapeutic target in wound healing.