Immunological and Endocrine Alterations in Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) is associated with an enhanced susceptibility to various somatic diseases. However, the exact mechanisms linking traumatic stress to subsequent physical health problems have remained unclear, with recent research discussing stress-related alterations in the endocrine and immune system as potential mediators. The present thesis is composed of three studies, investigating basal immune alterations as well as acute changes in immune and endocrine parameters in response to trauma reminders in patients with PTSD due to war and torture experiences. Study A investigated the influence of chronic stress associated with PTSD on alterations in T lymphocyte differentiation subsets. Results show a profoundly altered composition of the peripheral T cell compartment in PTSD patients, as evidenced by a substantial reduction in the proportion of regulatory T cells as well as a significantly reduced proportion of naïve cytotoxic T lymphocytes and enhanced proportions of memory T lymphocytes in individuals with PTSD compared to control subjects. Study B examined plasma cytokine levels as well as spontaneous and lipopolysaccharide (LPS)-stimulated cytokine production by peripheral blood mononuclear cells (PBMCs). Moreover, acute changes in plasma cytokines in response to the confrontation with trauma reminders were studied. Results demonstrate, that the spontaneous production of the pro-inflammatory cytokines Interleukin (IL) 1β, IL-6 and Tumor Necrosis Factor (TNF-α) by PBMCs was significantly higher in the PTSD compared to the control group. Moreover, in the PTSD patient group we found a positive association between PTSD symptom severity and plasma TNF-α levels following the confrontation with trauma reminders. Study C investigated the effect of trauma type (rape vs. other trauma types) on salivary and plasma cortisol responses of PTSD patients after being confronted with trauma reminders. Results demonstrate differential salivary cortisol responses in PTSD patients who had been raped compared to those who had not been raped. Whereas those PTSD patients with a past experience of rape showed a significant salivary cortisol increase when reminded of their traumatic events, salivary cortisol levels decreased in the course of the measurement period for the group who had not been raped. In sum, these findings might constitute a key factor in the enhanced susceptibility of persons with PTSD to a range of physical diseases. Moreover results support subtyping in relation to the type of traumatic stressors experienced. The nearness of the perpetrator during a traumatic event might modulate peritraumatic physiologic responses, as well as later physiological responses to trauma reminders