Stress-induced pro- and anti-inflammatory cytokine concentrations in female PTSD and depressive patients

Abstract

Alterations of the hypothalamus pituitary-axis on one hand and heightened rates of somatic diseases and mortality on the other hand are consistently found for PTSD and MDD patients. A possible link between these factors might be the immune system, in particular pro- and anti-inflammatory cytokines. A ‘low-grade inflammation’ in PTSD and MDD patients was found, whereas the influence of acute stress and the role of anti-inflammatory cytokines was rarely examined. In this study, 17 female PTSD patients participated in the Trier social stress test while serum cytokine levels (IL-6, IL-10) were assessed. Cytokine levels of PTSD patients were compared with levels of female depressive patients (n = 18) and female healthy controls (n = 18). Group differences were assessed using a 3 (group) x 8 (time: −15, −1, +1, +10, +20, +30, +45, +60 min) ANCOVA for repeated measures with baseline values as covariates. There was no group difference regarding IL-6 levels (p = 0.920) but PTSD patients showed significantly higher levels of IL-10 compared with depressive patients (p < 0.001, d = 0.16) and healthy controls (p = 0.001, d = 0.38). Under acute stress, PTSD patients did not show the widely found elevated IL-6 levels but showed an increase of anti-inflammatory IL-10. Therefore, acute stress seems to promote an imbalance of pro- and anti-inflammatory cytokine levels in PTSD and might indicate a hyperreactive immune response. This should be considered in future studies to further understand the role of the immune system as a link between stress response and somatic diseases.