CXCL8 and post-traumatic stress disorder: The Marine Resiliency Study reported that preexisting concentrations of C-reactive protein (CRP) were directly correlated with the occurrence and severity of PTSD, three months after a seven-month military deployment [10], and elevated levels of interleukin (IL)-6, IL-8, and transforming growth factor β (TGF-β) during hospitalization predicted the development of PTSD one month later [11].