IL6 and obesity due to melanocortin 4 receptor deficiency: The classically activated macrophages (M1 macrophages) from the SVF have been recognized as the main source of proinflammatory cytokines in WATs, such as tumor necrosis factor α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β), and as key participants in obesity-induced inflammation (Mathis, 2013).