Fig. 1

Macrophage polarization phenotypes and subtypes according to their different characteristics have many roles in immune responses. M1 macrophages have a pro-inflammatory role by their cytokines, but M2 macrophages, which are divided into four subtypes, have many different roles. For example, M2a macrophages play an important role in parasite killing, M2b macrophages function as immune system regulators, M2c macrophages assist in the wound healing process, and M2d macrophages have a pro-angiogenic role and are very important in tumor progression. CCL, C–C chemokine ligand; CXCL, C–X–C chemokine ligand; CXCR, C–X–C chemokine receptor; DCIR, dendritic cell immunoreceptor; IFN, interferon; IFNγ, interferon-γ; IL, interleukin; RELMα, resistin-like molecule-α; SPHK1, sphingosine kinase 1; TLR, Toll-like receptor; CD, cluster of differentiation; TGF-β, transforming growth factor-β; PPAR-γ, peroxisome proliferator-activated receptor gamma; TNF-α, tumor necrotic factor-α; YM1, chitinase-like protein 3; LPS, lipopolysaccharides; VEGF, vascular endothelial growth factor; MerTK, myeloid epithelial reproductive tyrosine kinase; DNMT, DNA methyl transferase; miRs, microRNAs; MHCII, major histocompatibility complex II; IGF, insulin-like growth factor