Irradiance, but not fluence, plays a crucial role in UVB-induced immature pigment cell development: new insights for efficient UVB phototherapy

Authors

  • Cheng-Che E. Lan,

    1. Department of Dermatology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
    2. Department of Dermatology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
    3. Department of Dermatology, Kaohsiung Municipal Ta-Tung Hospital, Kaoshiung Medical University, Kaohsiung, Taiwan
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  • Hsin-Su Yu,

    Corresponding author
    1. Department of Dermatology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
    • Department of Dermatology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
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  • Jian-He Lu,

    1. Graduate Institute of Medical Science, Kaohsiung Medical University, Kaohsiung, Taiwan
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  • Ching-Shuang Wu,

    1. Department of Medical Laboratory Science and Biotechnology, Kaohsiung Medical University, Kaohsiung, Taiwan
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  • Hsiao-Chi Lai

    1. Department of Dermatology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
    2. Department of Dermatology, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
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CORRESPONDENCE H.-S. Yu, e-mail: dermyu@kmu.edu.tw

Summary

Light exposure modulates development of living organisms. In the field of medicine, light has frequently been used for regenerative purposes. Excimer light (308 nm) has demonstrated superior efficacy in treating vitiligo, a condition requiring development of melanoblasts and a model for studying nerve cell regeneration, as compared to narrow-band ultraviolet B (NBUVB; 311 nm). Using mouse-derived melanoblast cells to examine the pro-differentiation effects of these two light sources, we demonstrated that at equivalent fluence, excimer light induces melanoblast differentiation, while NBUVB failed to so. Mechanistically, activation of aryl hydrocarbon receptor pathway and nuclear translocation of epidermal growth factor receptor are involved in pro-differentiation effects of excimer light. Reduction in irradiance by filter abrogated the effects of excimer light in melanoblasts, even when equivalent fluence was delivered by the same light source. As ultraviolet B (UVB) irradiation is closely associated pigment cell development, future therapy employing UVB for pigmentation purposes should incorporate irradiance as a crucial specification.

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