TNF and obesity due to melanocortin 4 receptor deficiency: Obesity-induced hyperleptinemia stimulates the production of pro-inflammatory cytokines such as TNF-α, IL-6, IL-2, IL-1β, and interferon-γ (IFN-γ) by monocytes and T-helper 1, and also inhibits the production of the anti-inflammatory cytokine IL-4 [35,36].