Evaluation of melanocyte stem cell population in vitiliginous skin pre- and post-narrow-band UVB phototherapy

Vitiligo vulgaris is an autoimmune disorder characterized by the destruction of epidermal melanocytes leading to white lesions devoid of pigmentation. The destruction of epidermal melanocytes. Is driven by tissue-resident and circulatory immune cells that maintain an inflammatory milieu. Two percent of the global population suffer from vitiligo vulgaris, of which, prevalence is higher in the Indian population. Narrow-band UV-B (NBUVB) phototherapy is commonly used as an economical, non-invasive, and well-tolerated treatment modality. NBUVB promotes the migration of melanocyte stem cells (MelSC) to the epidermis, thus regaining pigmentation in affected individuals. Despite the widespread use of NBUVB in secondary and tertiary clinics in India, the status of melanocyte stem cells and immune cells, pre-and post-NBUVB is not well understood. We observe that following NBUVB phototherapy, melanocyte stem cells (pax3+) re-populate the epidermis and express melanogenesis markers (Tyrosinase, Trp2, kit) concomitant with a decrease in CD3+ T-cells within the skin. Our study reaffirms the therapeutic efficacy of NBUVB in promoting re-pigmentation in an Indian cohort of vitiligo patients. Further, NBUVB is effective in reducing overall immune load, widely considered a major contributor to the pathogenesis of the disease.