CCL2 and obesity due to melanocortin 4 receptor deficiency: In detail, it is proved that in obesity, chronic low-grade inflammation is present since adipose tissue produces pro-inflammatory cytokines (e.g., TNF-α, IL-6), chemokines (monocyte chemoattractant protein (MCP1/CCL2) [53], and pro-inflammatory fatty acids [54], leading to systemic inflammation.