CCL2 and obesity due to melanocortin 4 receptor deficiency: Among the contributors to the biochemical and molecular mechanisms are the proinflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), and the chemokine monocyte chemoattractant protein-1 (MCP-1) which are produced by the macrophages that infiltrate the adipose tissue, and do so in increased numbers in obesity [9,10], the preadipocytes, and mature adipocytes [11,12].