M1 macrophages, prevalent in DN, initiate inflammation, tissue damage, and renal fibrosis via proinflammatory cytokines such as TNF-a, IL-6, IL-10, and monocyte chemoattractant protein 1 (MCP-1) (Kim et al., 2015; Wang et al., 2017). The gene discussed is CCL2; the disease is renal fibrosis.