SFRP2 modulates functional phenotype transition and energy metabolism of macrophages during diabetic wound healing [Skin wound]

Diabetic foot ulcer (DFU) is a serious complication of diabetes mellitus, which causes great health damage and economic burden to patients. The pathogenesis of DFU is not fully understood.We screened wound healing-related genes using bioinformatics analysis, and full-thickness skin injury mice model and cellular assays were used to explore the role of target genes in diabetic wound healing. SFRP2 was identified as a wound healing-related gene, and the expression of SFRP2 is associated with immune cell infiltration in DFU. In vivo study showed that suppression of SFRP2 delayed the wound healing process of diabetic mice, impeded angiogenesis and matrix remodeling, and increased macrophage infiltration in wound tissues. In addition, suppression of SFRP2 enhanced M1 polarization in both the early and later stage of wound healing, and decreased M2 polarization in the later stage, which impeded the transition of M1 to M2 polarization of wound healing. Moreover, suppression of SFRP2 affected the transcriptome signatures-related to inflammatory response and energy metabolism at the early stage of wound healing. Extracellular flux analysis (EFA) showed that suppression of SFRP2 decreased mitochondrial energy metabolism and increased glycolysis in injury-related macrophages. Furthermore, suppression of SFRP2 inhibited transcriptome signaturesrelated to carbohydrate metabolism, lipid metabolism and amino acid metabolism, which consists the three main components of energy metabolism of macrophages. In conclusions, SFRP2 may function as a wound healing-related gene in DFU, and suppression of SFRP2 impaired diabetic wound healing by compromising the M1-to-M2 transition of macrophages and modulating the balance between mitochondrial energy metabolism and glycolysis.