These cytokines contribute to the chronic inflammatory state (Alpert et al., 2021) and exacerbate PTSD symptoms by disrupting the gut-brain axis, as can be observed, for example, by the fact that another downstream acute-phase protein, c-reactive protein, secreted by the inflammatory cytokine IL-6, is significantly elevated in people with PTSD (Miller et al., 2018). This evidence concerns the gene CRP and post-traumatic stress disorder.