Changes in adipocyte characteristics, such as fat accumulation, increased expression of monocyte chemoattractant protein-1 (MCP-1), increased secretion of TNF-α and leptin, and decreased secretion of adiponectin, under conditions of obesity can lead to macrophage infiltration, which further aggravates disordered lipid metabolism, insulin resistance and inflammation spread 78. Here, CCL2 is linked to obesity due to melanocortin 4 receptor deficiency.