Fig. 1
From: Relevance and consequence of chronic inflammation for obesity development
Components of the leptin-melanocortin signaling pathway contribute to immunological functions. Leptin is produced by the adipose tissue and binds centrally to the leptin-receptor. This activates the production and processing of POMC into α-MSH among others. Α-MSH binds to the MC4R, which initiates a feeling of satiety and leading to a reduction and food intake. The components of this pathway also contribute to inflammatory functions. Leptin acts via binding to the Leptin-receptor and increases hematopoiesis and lymphopoiesis. It activates neutrophils, NK, monocytes, dendritic cells, and macrophages and promotes a Th1-type production of pro-inflammatory cytokines. Α-MSH has been shown to downregulate pro-inflammatory cytokines such as IL-1, IL-6, and TNFα and immunomodulatory cytokines like IL-2, IL-4, IL-13, and INFγ. It also reduces the production of IgE and NO