Selective Anti-Inflammatory Actions of Curcumin on Cytokine Pathways in Major Depressive Disorder

Major depressive disorder (MDD) is a prevalent mental illness with a significant disease burden. It is characterized by immune-inflammatory dysregulation.

This ex vivo study assessed curcumin's immunomodulatory effects in 18 MDD patients and 18 healthy controls (HC). Whole blood samples underwent LPS- and PHA-stimulation to evaluate immune sensitization with curcumin treatment at concentrations of 2, 20, and 200 ng/mL.

MDD patients exhibited marked activation of the immune-inflammatory response system (IRS), M1 macrophages, T helper (Th) 1, growth factors, and chemokine profiles, whereas M2, Th2, and the compensatory immunoregulatory system (CIRS) were less activated, confirming IRS sensitization in MDD. Partial regression analysis confirmed positive correlations between immune biomarkers (e.g., IL-1β) and depression severity scores. In patients with MDD, curcumin selectively and significantly downregulated the overactivated IRS, M1, Th1, and chemokine profiles. Notably, curcumin significantly decreased pro-inflammatory chemokines, such as CCL11, CXCL10, and CCL27, and exhibited inhibitory effects on key inflammatory factors, including TNF-α. Although curcumin did not fully normalize the IRS profiles or significantly affect M2, Th2, or CIRS profiles, its specific inhibition of core inflammatory pathways clearly demonstrates its ability to selectively modulate aberrant immune responses in MDD. Paradoxically, in HC, curcumin showed mild immune-stimulating effects.

These findings demonstrate that curcumin exerts selective anti-inflammatory effects by effectively targeting and suppressing overactivated core inflammatory pathways (e.g., IRS/M1/Th1 and related chemokines) in MDD patients, thereby partially restoring immune homeostasis. This supports the potential role of curcumin as an adjunctive therapeutic strategy for MDD. However, as these findings are derived from an ex vivo model, further in vivo studies are required before clinical recommendations can be made.