The Role of Cytokines in the Peripheral Blood of Major Depressive Patients

Abstract

Recent technological advances offer an opportunity to further elucidate the complex cytokine network in Major Depressive Disorder (MDD). The objective of this study was to investigate the role of pro-inflammatory and anti-inflammatory cytokines in the mechanism of depressive disorders. Given the activating role of cytokines on the hypothalamic-pituitary-adrenal (HPA) axis, and the relevance of its regulation in MDD, we also analyzed the relationships between several cytokines and cortisol levels. Twenty-five unipolar depressive patients and 20 healthy controls were recruited in this study. Flow cytometric bead array system (FCM-CBA) was used to examine the concentration of cytokines (IL-2, IL-4, IL-6, IL-10, TNF, INF-α) in peripheral blood. Plasma Adrenocorticotropic Hormone (ACTH) and serum cortisol concentrations were detected. Compared with the controls, depressive patients had a significant increase in concentration of IL-2, TNF, serum cortisol, and TNF/IL-4 (p < 0.05). There was a significant positive correlation between serum cortisol and IL-2, as well as ACTH and IL-2 (p < 0.05) in depressive patients. There was a significant positive correlation between IL-2 and the Hamilton depression rating scale (HAMD) total scores in depressive patients, and also with TNF (p < 0.05). There was no significant difference in concentration of IL-4, IL-6, IL-10, and INF-α between two groups (p > 0.05). The present results suggest that depressive patients had an increase in concentration of some pro-inflammatory cytokines. Both IL-2 and TNF play important roles in the development of depressive disorders, and their concentration in peripheral blood may be used to evaluate the severity of depressive disorders.