IL6 and obesity due to melanocortin 4 receptor deficiency: Obesity induces elevated expression levels of IL-6, granulocyte colony-stimulating factor (G-CSF), and granulocyte-macrophage colony-stimulating factor, which increase the expression of cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed death-ligand 1 (PD-L1) to suppress T cell cytotoxicity [82].