TNF and obesity due to melanocortin 4 receptor deficiency: Evidence for a chronic, low-grade inflammatory state in obesity is represented principally by marked increases in plasma levels of proinflammatory cytokines such as tumor necrosis factor (TNF)-a and interleukin (IL)-6, and proinflammatory chemokines such as monocyte chemoattractant protein (MCP)-1 [34].