Diminished functional properties of T regulatory cells in major depressive disorder: The influence of selective serotonin reuptake inhibitor

Abstract

The properties of CD4+CD25hi T regulatory cells (Tregs), and interleukin (IL)-2 pathway were investigated in major depressive disorder (MDD) patients treated with or without selective serotonin reuptake inhibitor (SSRI).The frequencies of FOXP3 and pSTAT5 in peripheral Tregs were found to be diminished in untreated patients (SSRI−) versus HCs (p < .001 for both), while their percentages were increased in treated patients (SSRI+) versus untreated patients (p < .001 and p = .04). The proliferation of CD4+ T cells was higher in SSRI−MDD patients versus HCs (p = .03). The SSRI−MDD patients showed a lower concentration of supernatant TGF-β than HCs (p = .001), while the production of TGF-β was enhanced in SSRI+MDD versus SSRI−MDD patients (p = .003). The number of CD45RA-expressing Tregs, the expression of JAK1 and JAK3, and the levels of IL-2 and IL-10 were similar between the patients and HCs.The study results showed that untreated patients have an impaired IL-2 signaling pathway and defective Tregs, and SSRI treatment may improve the Tregs function.