Evaluation of Melanocytes and T-cells in Vitiliginous Skin Pre- and Post-Narrow-Band UVB Phototherapy.

BACKGROUND

Vitiligo 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 circulating immune cells that maintain an inflammatory milieu. Two percent of the global population suffers from vitiligo, with a higher prevalence reported 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 restoring pigmentation in affected individuals.

AIMS AND

OBJECTIVES

This study aimed to investigate the histological and gene expression changes in Indian vitiligo patients pre- and post-NBUVB phototherapy.

PATIENTS AND

METHODS

Indian patients with stable vitiligo underwent NBUVB monotherapy, administered thrice weekly for three months, to induce repigmentation. Single 3 mm skin biopsies were taken from vitiligo lesions pre- and post-NBUVB phototherapy for histopathological and gene expression analysis. A contralateral pigmented region was considered as the control skin from the same patient.

RESULTS

Following NBUVB monotherapy, melanocytes were restored in the epidermis of vitiligo patients and produced melanin pigment. The mean area of pigmentation post-NBUVB therapy was 2.94% ± 0.97%, compared to 0.11% ± 0.19% in vitiligo lesions before NBUVB therapy. Following NBUVB phototherapy, melanocytes migrating from the hair bulge upregulated key genes in melanocyte differentiation (PAX3) and melanogenesis (KIT, TYR, DCT/TRP2). In addition to the favorable clinical outcome of repigmentation, NBUVB was effective in reducing the skin T-cells, indicating successful immunosuppression.

LIMITATIONS: The major limitation of our study was the limited sample size of our patient cohort.

CONCLUSIONS

Our study reaffirms the therapeutic efficacy of NBUVB in promoting repigmentation in an Indian cohort of vitiligo patients. Furthermore, NBUVB is effective in reducing CD3+ skin-resident T-cells, widely considered a major contributor to the pathogenesis of the disease.