Vitiligo: A focus on pathogenesis and its therapeutic implications.

Vitiligo is the most common depigmenting disorder affecting 0.1%-2% of the population worldwide. The characteristic white patches result from the selective loss of melanocytes. Sustained recent efforts have resulted in a detailed understanding of the genetic architecture of vitiligo. About 80% of vitiligo risk is attributable to genetic factors; and the rest (20%) is attributable to the environment. Over the past decade, substantial progress has been made in our understanding of the pathogenesis of vitiligo which is now clearly classified as an autoimmune disease. Melanocytes from patients with vitiligo are more susceptible to oxidative stress which begets the release of exosomes and inflammatory cytokines that will lead to activation of the innate immune response and subsequently to adaptive immune response through activation of autoreactive cytotoxic CD8+ T cells. These produce interferon-γ (IFN-γ) which promotes disease progression through IFN-γ-induced chemokine secretion from surrounding keratinocytes to further recruit T cells to the skin through a positive feedback loop. CD8 tissue-resident memory T cells are in turn responsible for long-term maintenance and potential relapse of vitiligo in human patients through cytokine-mediated recruitment of T cells from the circulation. This review summarizes the current knowledge on vitiligo and attempt to give an overview of the future in vitiligo treatment.