Participation of T cell immunoglobulin and mucin domain-3 (TIM-3) and its ligand (galectin-9) in the pathogenesis of active generalized vitiligo

Vitiligo is a depigmentary disease where melanocytes of the basal layer of epidermis are selectively destroyed by immune-cell-mediated cytotoxicity. The T cell immunoglobulin- and mucin-domain-containing molecules (TIMs) are involved in immune regulation, and their participation is not known in vitiligo. The present study revealed significant increase in the percentage of CD3+CD4+TIM3+ T cells (P < 0.05) in peripheral blood and was positively correlated with percentage body surface area involvement in aGV group. Further, increased expression of TIM-3 and its ligand galectin-9 (Gal-9) mRNA was found in peripheral blood and lesional/perilesional skin of active generalized vitiligo (aGV) compared with controls. Characteristic migration pattern of TIM-3-positive immune cells in lesional (near/in the epidermis) and perilesional (towards epidermis) skin section suggested that TIM-3+ immune cells may be involved in melanocyte destruction. Further, investigation is required to understand the role of TIM-3/Gal-9 signalling pathways in aGV and it can be targeted in the management of vitiligo.