CXCL8 and depressive disorder: With regard to the analysis of pro-inflammatory cytokines IL-6 and IL-8, our data are in line with overall inconclusive findings regarding concentrations and effects of pro-inflammatory cytokines in depression (Himmerich et al., 2019; Köhler et al., 2017; Lamers et al., 2020; Tsai, 2021).