CCL2 and obesity due to melanocortin 4 receptor deficiency: Of note, during obesity, up-regulated levels of pro-inflammatory adipokines like IL-1β, IL-6, MCP-1, tumor necrosis factor-α (TNF-α), PAI-1, leptin and resistin, and down-regulated levels of anti-inflammatory adipokines such as adiponectin and IL-10, lead to a chronic state of low-grade inflammation.