CCL2 and obesity due to melanocortin 4 receptor deficiency: Obesity-induced increased levels of glucose and FFAs create stress in pancreatic islets, adipose tissue, liver, and muscle, resulting in increased local production and release of cytokines and chemokines such as IL-1β, TNFα, CCL2, CCL3, and CXC-chemokine ligand 8 (CXCL8, also known as IL-8).