Transcriptional upregulation of Nrf2-dependent phase II detoxification genes in the involved epidermis of vitiligo vulgaris.

Oxidative stress is widely believed to be a contributing factor in vitiligo pathogenesis. To explore mechanisms by which epidermis responds to mounting oxidative stress, we investigated the involvement of phase II detoxification genes in vitiligo. Phase II detoxification pathways have recently been identified as being important in the regulation of epidermal skin homeostasis. In this study we show that the key transcription factor nuclear factor E2-related factor 2 (Nrf2) and the downstream genes NAD(P)H:quinone oxidase-1 (NQO-1), γ-glutamyl cystine ligase catalytic subunit (GCLC), and γ-glutamyl cystine ligase modifying subunit (GCLM) are upregulated in the lesional epidermal skin of subjects with vitiligo vulgaris. The differences between lesional and nonlesional skin were further investigated by studying the induced expression of Nrf2-dependent transcripts in skin punch biopsies using curcumin and santalol. Surprisingly, nonlesional skin showed induction of all transcripts while a similar effect was not observed for the skin punches from the lesional skin. The use of curcumin and santalol on epidermal cells showed that keratinocytes were more susceptible to apoptosis, whereas melanocytes induced phase II genes under the same concentrations with negligible apoptosis. Our studies provide new insights into the role of phase II detoxification pathway in maintaining skin homeostasis and sustaining redox balance in vitiligo patients.