Altered circulating memory T cells in vitiligo cases followed NB-UVB therapy

Abstract

Background: Vitiligo represents a commonly diagnosed autoimmune disease caused by the depletion of epidermal melanocytes. Many subsets of T cells contribute to vitiligo pathogenesis, including resident and circulating memory T cells. Objectives: To analyze the amounts of CD4+ and CD8+memory T-cell subsets in peripheral blood specimens from vitiligo patients and alterations caused by narrowband ultraviolet B (NB-UVB) phototherapy. Methods: Circulating CD4+ and CD8+ central memory T (TCM) and effector memory T (TEM) cell frequencies in 33 patients with non-segmental vitiligo and 16 healthy donors were evaluated by flow cytometry. Related chemokine levels were also detected. Results: Peripheral blood CD4+ TCM and CD8+ TCM counts were markedly reduced in vitiligo cases while they were higher in active vitiligo compared with stable vitiligo cases. Circulating CD8+ TCM frequency in vitiligo was closely related to disease duration. Interestingly, CD4+ TCM and CD8+ TCM frequencies, alongside CXCL9 and CXCL10 amounts in peripheral blood of patients with vitiligo, were significantly decreased after NB-UVB phototherapy. Conclusions: Decreased frequencies of circulating CD4+ TCM and CD8+ TCM by NB-UVB suggest a possible immunosuppressive effect of phototherapy. The chemokines CXCL9 and CXCL10 are the bridge between circulating and skin resident memory T cells. NB-UVB blocks the homing of circulating memory T cells into vitiligo lesions by down-regulating CXCL9 and CXCL10. Targeting the above proteins could provide novel, durable treatment options to cure and prevent flares of this disease.