Indeed, proinflammatory cytokines, including IL-1beta, interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha), have been implicated in the etiology of depression, contributing to cellular damage, impaired neuronal plasticity, and neurotransmission in the prefrontal cortex and hippocampus (Felger and Lotrich 2013). This evidence concerns the gene IL6 and depressive disorder.