IL17A and post-traumatic stress disorder: PTSD patients are characterized by increased systemic levels of inflammatory cytokines, including IFNγ, TNFα and IL17A, as well as increased levels of inflammatory immune cells, including Th1 and Th17 cells (Hori and Kim, 2019; Wang et al., 2017; Zhou et al., 2014; Von Kanel et al., 2007; Wang et al., 2016; Guo et al., 2012).