The role for miRNA146b-5p in the attenuation of dermal fibrosis and angiogenesis by targeting PDGFRα in skin wounds

As a candidate microRNA antifibrotic effector in skin wounds, miR-146b-5p was upregulated by basic FGF, and PDGFRα was identified as a direct target of miR-146b-5p in fibroblasts. The treatment of fibroblasts with a miR-146b-5p mimic markedly downregulated the expression of PDGFRα and collagen type I. miR-146b-5p mimic transfection in wounds markedly attenuated cutaneous fibrosis, whereas a miR-146b-5p inhibitor strongly promoted fibrosis, with increases in PDGFRα and collagen I levels. These results indicate the positive effects of miR-146b-5p for the suppression of fibrosis, possibly through the inhibition of PDGFRα. The miR-146b-5p inhibitor markedly increased CD34+ vessel numbers and CD34 expression in wounds. We found miR-146b-5p+ cells in close contact with S100+ adipocytes. Moreover, we discovered the specific colocalization of the exosome marker CD81 and miR-146b-5p in the adipose tissue cells of mimic-transfected wounds, with miR-146b-5p signals being detected in the FSP1+ fibroblastic cells of adipose tissues. Therefore, fibroblastic cells of adipose tissues, which may specifically pick up and contain miR-146b-5p by exosome after transfection, may play an important role in the suppression of fibrosis. In this process, the inhibition of PDGFRα in adipose tissue cells by miR-146b-5p may lead to the loss of their PDGFRα-induced profibrotic activities, thereby suppressing fibrosis.