42 °C heat stress pretreatment protects human melanocytes against 308-nm laser-induced DNA damage in vitro

308-nm excimer laser combined with piperine promotes melanin synthesis through PTEN/PDK1/GSK3b regulation of keratinocyte paracrine

Vitiligo is a common skin disorder involving depigmentation. A 308-nm excimer laser and piperine were shown to be useful for the treatment of vitiligo. The aim of this study was to investigate the effect of a 308-nm excimer laser combined with piperine in the treatment of vitiligo and the molecular mechanism by which this treatment promotes melanin synthesis through regulation of the paracrine activity of keratinocytes (KCs). In this study, cells and animals were treated with a 308-nm excimer laser and piperine. ELISA, Western blot analysis, immunofluorescence and RT‒qPCR were used to measure the levels of proteins and genes, and EdU, Transwell, and flow cytometric assays were used to assess cell proliferation and apoptosis. Treatment with the 308-nm excimer laser combined with piperine promoted KCs secretion of cytokines related to melanin production, restrained the secretion of proinflammatory cytokines, elevated the level of PTEN, decreased the level of PDK1, inhibited the phosphorylation of Akt, and facilitated the phosphorylation of GSK3b. After coculture of melanocytes (MCs) with KCs supernatant, the proliferation and migration of MCs increased, the apoptosis of MCs decreased, and the expression of melanin synthesis-related genes increased. Moreover, compared with the 308-nm excimer laser or piperine alone, the combined treatment had a more significant effect. Moreover, inhibiting PTEN weakened the effect of the combined treatment. Animal experiments revealed that a 308-nm excimer laser combined with piperine had a therapeutic effect on vitiligo. After combined treatment, the number of CD8 + T cells decreased, and the PTEN/PDK1/GSK3b pathway was activated, which increased melanin synthesis and alleviated the progression of vitiligo. In conclusion, a 308-nm excimer laser combined with piperine regulates KCs paracrine activity through the PTEN/PDK1/GSK3b molecular axis, promotes MCs proliferation and melanin synthesis, and alleviates the progression of vitiligo, which provides new targets for the clinical treatment of vitiligo.

The role of excimer light in dermatology: a review

Excimer light is a subtype of NB-UVB that emits a 308 nm wavelength, and can provide targeted phototherapy treatment. The absorption of 308 nm light by skin cells leads to therapeutic response in various common and ultraviolet-responsive skin diseases, such as psoriasis and vitiligo, and photo-resistant skin diseases such as prurigo nodularis, localized scleroderma, genital lichen sclerosis, and granuloma annulare, cutaneous T-cell lymphomas, among others. Excimer light has few adverse reactions and overall is well tolerated by patients, furthermore, it can be performed in places that are difficult to access. This article aims to explain the therapeutic bases and applications of excimer light in current dermatology.

The impaired unfolded protein-premelanosome protein and transient receptor potential channels-autophagy axes in apoptotic melanocytes in vitiligo

Vitiligo is an autoimmune skin disease, characterized by depigmentation and epidermal melanocytes loss. The specific mechanisms underlying vitiligo have not been fully understood. As a result, treating vitiligo is a dermatological challenge. Recently, much attention has been paid to the dysfunction and interaction of organelles under environmental stress. The impaired organelles could generate misfolded proteins, particularly accumulated toxic premelanosome protein (PMEL) amyloid oligomers, activating the autoimmune system and cause melanocyte damage. Unfolded protein response (UPR) dysfunction accelerates toxic PMEL accumulation. Herein, we presented a narrative review on UPR's role in vitiligo, the misfolded PMEL-induced attack of the autoimmune system under autophagy dysfunction caused by abnormal activation of transient receptor potential (TRP) channels and the background of UPR system defects in melanocytes. All of these mechanisms were integrated to form UPR/PMEL-TRP channels/autophagy axis, providing a new understanding of vitiligo pathogenesis.