Furthermore, individuals with depression have significantly higher levels of inflammatory cytokines (40), such as interleukin-1 (IL-1), interleukin-4 (IL-4), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α), which are also important mediators in the pathogenesis of asthma (41). This evidence concerns the gene IL6 and major depressive disorder.