CCL2 and obesity due to melanocortin 4 receptor deficiency: Obesity per se results in a chronic state of low-grade systemic inflammation, mediated by excess adipocyte production of pro-inflammatory cytokines including interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1) and interleukin-8 (IL-8) [9], [10], [11].