Acceleration of melanocyte senescence by the proinflammatory cytokines IFNγ and TNFα impairs the repigmentation response of vitiligo patients to narrowband ultraviolet B (NBUVB) phototherapy

Vitiligo is a chronic autoimmune disease characterized by the T helper 1 (Th1) cytokine-driven immune destruction of melanocytes (MCs). Although narrowband ultraviolet B (NBUVB) phototherapy has been proven to be an effective therapeutic option, the repigmentation response to that phototherapy varies greatly in different vitiligo patients. Here, we demonstrate that there is an increase of NBUVB-induced cellular senescence in vitiligo MCs exposed to Th1 cytokine interferon γ (IFNγ) and/or tumor necrosis factor α (TNFα) in lesional vitiligo skin from poor responders who had undergone NBUVB phototherapy. Supplementation with exogenous recombinant human stem cell factor (rhSCF) in the culture medium as well as the lentiviral vector–mediated overexpression of cKIT could prevent the MCs from the IFNγ/TNFα-accelerated cellular senescence. Mechanistic studies indicated that the reduced ratio of membrane-bound KIT (mKIT) to the soluble form of KIT (sKIT) is directly related to the cellular senescence of vitiligo MCs following exposure to IFNγ and TNFα. Furthermore, the matrix metalloprotease 9 (MMP9) inhibitor GM6001 attenuates the production of sKIT via the suppression of cKIT ectodomain shedding. Altogether, our study indicates that the presence of Th1 cytokines IFNγ and/or TNFα in the epidermal milieu might impair the repigmentation response of vitiligo patients to NBUVB phototherapy.