IL6 and major depressive disorder: Affective disorders and depression are associated with high levels of oxidative stress markers [such as 8-hydroxydeoxyguanosine (8-OHdG)], proinflammatory cytokines (such as interleukins (IL) IL-1 and IL-6 and tumor necrosis factor alpha (TNFα)), as well as with decreased levels of antioxidants (such as coenzyme Q10, glutathione peroxidase, and zinc) (Ng et al., 2008; Maes et al., 2011; Leonard and Maes, 2012; Lindqvist et al., 2017).