CCL2 and obesity due to melanocortin 4 receptor deficiency: Several stimuli were suggested to mediate the induction of leukocyte recruitment to adipose tissue found upon obesity such as the following: (1) activation of adipocyte proinflammatory pathways by LPS and saturated fatty acids and secretion of chemokines such as monocyte chemoattractant protein-1 (MCP-1), (2) tissue hypoxia, (3) adipocyte death, and (4) mechanical stress between adipocytes and the extracellular matrix [6].