IL6 and obesity due to melanocortin 4 receptor deficiency: Obesity activates various proinflammatory pathways, which includes elevated level of cytokines such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), C-reactive protein (CRP), plasminogen activator inhibitor-1 (PAI-1), and leptin (Figure 2) (37, 41).