SERPINE1 and obesity due to melanocortin 4 receptor deficiency: FFAs and lipid-derived mediators are ligands for immune receptors such as Toll-like receptors and G-protein coupled receptors and can thus initiate an innate immune response [9] to induce the increase of inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and plasminogen activator inhibitor-1 (PAI-1) as seen in obesity and IR [10,11].