Proinflammatory cytokines, such as TNF-a, IL-1, and IL-6, are the major mediators between the brain, HPA axis, and immune system and continuous prolonged upregulation of proinflammatory cytokines can lead to depression and HPA axis suppression, which may trigger exacerbation of asthma [39–41]. This evidence concerns the gene IL6 and depressive symptom measurement.