Obesity-induced insulin resistance was found to be improved in TNF-α knockout mice, and elevated levels of TNF-α were observed to enhance the production of the pro-inflammatory factors MCP-1 and IL-6, as well as downregulating the expression of anti-inflammatory adipokines such as adiponectin [19,20]. The gene discussed is CCL2; the disease is obesity due to melanocortin 4 receptor deficiency.