Macrophage-Mediated Inflammation in Skin Wound Healing

Abstract

Macrophages are key immune cells that respond to infections, and modulate pathophysiological conditions such as wound healing. By possessing phagocytic activities and through the secretion of cytokines and growth factors, macrophages are pivotal orchestrators of inflammation, fibrosis, and wound repair. Macrophages orchestrate the process of wound healing through the transitioning from predominantly pro-inflammatory (M1-like phenotypes), which present early post-injury, to anti-inflammatory (M2-like phenotypes), which appear later to modulate skin repair and wound closure. In this review, different cellular and molecular aspects of macrophage-mediated skin wound healing are discussed, alongside important aspects such as macrophage subtypes, metabolism, plasticity, and epigenetics. We also highlight previous studies demonstrating interactions between macrophages and these factors for optimal wound healing. Understanding and harnessing the activity and capability of macrophages may help to advance new approaches for improving healing of the skin.

Keywords: inflammation; macrophages; wound healing.

Figure 1

M1 and M2 polarization of macrophages. M1 macrophages produce pro-inflammatory cytokines, mediate resistance to pathogens, and possess strong microbicidal properties. M2 macrophages, on the other hand, are anti-inflammatory macrophages that mediate inflammation resolution and contribute to wound healing by promoting angiogenesis.

Figure 2

Different diseases and pathological conditions such as diabetes and obesity, epigenetic elements, and different cellular activities can induce inflammation by affecting macrophages functions which promote M1 macrophages activities.