Abnormal Cytokines in Trauma Patients Explained by Obesity, Musculoskeletal Disease, Smoking, and Lung Disease

Low-grade inflammation observed through abnormal plasma cytokine levels has been associated with post-traumatic stress disorder (PTSD). It is not clear whether PTSD independently causes the inflammation or if it is mainly through co-occurring somatic factors such as smoking and obesity. We wanted to explore the effects of biopsychosocial factors on cytokine levels in a clinical setting.

The sample consisted of 51 patients with PTSD, 58 trauma patients without PTSD, and 40 matched controls. We selected cytokines and relevant risk factors for systemic inflammation through pairwise correlations. Then, we used linear regression to analyze the individual and combined effects of these on the (Log10) cytokines, particularly estimating the effect of PTSD adjusted for other factors.

Higher age, female gender, cigarette smoking, presence of lung and musculoskeletal disease, use of antipsychotic medication, and higher BMI were correlated with higher levels of interleukins IL-1RA, IL-2RA, and IL-6. In the adjusted regression analysis, higher BMI was associated with increased IL-1RA (B = 0.06, p < 0.01), IL-2RA (B = 0.01, p < 0.01), and IL-6 (B = 0.01, p = 0.03). Presence of musculoskeletal disease was associated with increased IL-1RA (B = 0.72, p < 0.01) and IL-6 (B = 0.16, p = 0.01), and decreased IL-2RA (B = -0.09, p < 0.01). Cigarette smoking (B = 0.16, p = 0.01) and presence of lung disease (B = 0.14, p = 0.02) were associated with increased IL-6. PTSD diagnosis was associated with decreased IL-2RA (B = -0.06, p = 0.04).

Altered cytokine levels in distressed trauma-affected individuals are probably mostly through co-occurring risk factors and not PTSD diagnosis. Increased BMI and musculoskeletal (pain) disease may be particularly strong risk factors and should be addressed.