CCL2 and obesity due to melanocortin 4 receptor deficiency: There is a chronic low-grade inflammation developing in obesity, mediated by inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and interleukin 8 (IL-8) (Zeyda and Stulnig, 2009).