CCL2 and obesity due to melanocortin 4 receptor deficiency: The obesity epidemic has increased the prevalence of diabetes, making diabetes one of the leading causes of death in the U.S. The excess adipose tissue (AT) seen in obesity disturbs cellular homeostasis and upregulates the production of inflammatory markers, including tumor necrosis factor α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), and interleukin 6 (IL-6).