Impact of Vitamin D and Curcumin on CD4+ and CD8+ T cells Expressing CXCR3, CCR4, and CCR6 Chemokine Receptors in Patients with Relapsing-remitting Multiple Sclerosis.

Chemokines and their receptors play a central role in mediating the migration of pathogenic T cells into the central nervous system of patients with multiple sclerosis (MS). Vitamin D and curcumin are known to possess anti-inflammatory and immunomodulatory properties; however, their combined effects on T-cell chemokine receptor expression in MS remain poorly defined. In this study, we investigated the in vitro effects of vitamin D, curcumin, and their combination on CD4+ and CD8+ T cells expressing CXCR3, CCR6, and CCR4 in patients with relapsing-remitting MS (RRMS). Peripheral blood mononuclear cells were collected from patients in relapse (n=10), remission (n=14), and healthy controls (n=15) and analyzed using flow cytometry. Relapse patients exhibited elevated frequencies of CXCR3+CD4+ T cells compared to healthy controls, which normalized following treatment. Increased CCR6+CD4+ T cells and CXCR3+CD8+ T cells were also observed in patients, with a significant reduction achieved only after combined treatment with vitamin D and curcumin. The combined treatment further decreased the mean fluorescence intensity of CXCR3 and CCR6 on T cells in relapse patients, while vitamin D alone specifically reduced CCR4+CCR6+CD4+ T cells, a TH17-like subset enriched during relapse. These findings indicate that vitamin D and curcumin, particularly in combination, modulate T-cell activity by downregulating chemokine receptor expression and may represent a promising adjunctive approach for controlling immune cell migration in MS.