TLR4 and obesity due to melanocortin 4 receptor deficiency: This review focuses on obesity-induced inflammation in adipose tissue (adipose tissue inflammation) as the origin of chronic inflammation in metabolic syndrome and the role of two innate immune receptors, namely, Toll-like receptor 4 (TLR4) and macrophage-inducible C-type lectin (Mincle), in the interaction between adipocytes and macrophages.