IL6 and obesity due to melanocortin 4 receptor deficiency: When lipopolysaccharide (LPS) is applied to stimulate inflammation in macrophages, the first receptor is Toll-like receptor (TLR) 4, which activates downstream pathways and induces various pro-inflammatory cytokines, such as chemokine (C–C motif) ligand 2 (CCL2), interferon-γ (IFN-γ), interleukin 1β (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor-α (TNFα), as obesity does13.