IL6 and obesity due to melanocortin 4 receptor deficiency: Macrophages are the most abundant immune cells in AT, can change to classically activated (M1)- or metabolically activated-like phenotypes in obesity, and play an important role in AT inflammation by secreting proinflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β)[10–17].