Regarding the activation of macrophages, Saa3 has been shown to promote the infiltration of macrophages in adipose tissue (41), while S100a8 plays a central role in obesity-promoting macrophage-based inflammation (42) and induces the secretion of cytokines from mononuclear cells (43). The gene discussed is S100A8; the disease is obesity due to melanocortin 4 receptor deficiency.