CCL2 and obesity due to melanocortin 4 receptor deficiency: As a major endocrine organ, WAT also secretes hormones such as adiponectin, leptin, resistin, and cytokines such as tumor necrosis factor-alpha (TNF-α), IL-6, and monocyte chemotactic protein-1 (MCP-1), which play a role in regulating whole-body metabolism, insulin resistance, and low-grade systemic inflammation connected with obesity [35, 36].