Elevated TNIP3 mRNA Expression in TNF-α-Secreting Cells from Patients with Major Depressive Disorder

Elevated levels of pro-inflammatory cytokines, in particular tumor necrotic factor alpha (TNF-α), and abnormalities in negative regulation in Toll-like receptor (TLR) signaling pathways are associated with major depressive disorder (MDD). Previous research by our group disclosed lower expression of TNF-α-induced protein 3 (TNFAIP3), one of the negative regulators of the TLR4 signaling pathway, in depressive patients than in healthy controls.In this study, we assessed the mRNA levels of TNFAIP3, TNFAIP3-interacting proteins (TNIP), including TNIP1, TNIP2, and TNIP3, and TNFAIP3-like proteins, such as cezanne1, cezanne2, trabid, and VCIP135, in TNF-α-secreting cells and examined their association with severity of depression using the 17-item Hamilton Depression Rating Scale (HAMD-17) scores from 30 MDD patients and 30 healthy controls. Twenty-six patients received a second assessment after treatment with antidepressants for 4 weeks.TNF-α-secreting cells displayed higher TNIP3 mRNA expression in MDD patients than in healthy controls before treatment, which was marginally decreased after antidepressant treatment. In addition, the TNIP2 level could be effectively applied to predict changes in HAMD scores after linear regression analysis.Our collective findings suggest that molecules associated with negative regulation of innate immunity are aberrantly expressed in patients with MDD and present potential therapeutic targets.