Induced skin aging by blue-light irradiation in human skin fibroblasts via TGF-, JNK and EGFR pathways

Background: Studies indicate that blue light (BL) irradiation can damage human skins, but the impact of BL irradiation on skin aging is unknown. Objectives: This study aimed to give an insight to phenotypic characteristics and molecular mechanism of blue light-induced skin aging, and thus provide a theoretical basis for the precise protection of photodermatosis. Methods: The effect of BL on skin photoaging in mice was evaluated by non-invasive measurement equipment and histopathology analysis. The effect of BL irradiation on the proliferation of HFF-1 cells was detected by the Real-Time Cell Analyzer. The expression and protein levels of genes associated with skin aging were examined. Results: Our studies indicated photoaging caused by BL irradiation, including collagen disorder and increased MMP1. BL irradiation also inhibited cell proliferation and collagen expression in human skin fibroblasts by inhibiting TGF-beta signaling pathway, based on in vitro experiments. Importantly, BL irradiation promoted the degradation of collagen by increasing MMP1 activated by the JNK/c-Jun and EGFR pathways. Moreover, ROS levels were significantly increased after BL irradiation in human skin fibroblasts. Yet, the transcriptional change in human skin fibroblasts caused by BL irradiation was unable to be completely restored by ROS scavenger. Conclusion: BL irradiation down-regulated expression of type I collagen genes and up-regulated MMP1 expression to inhibit the proliferation of human skin fibroblasts. Multiple key pathways including TGF-beta, JNK, and EGFR signaling were involved in BL-induced skin aging. Our results provide theoretical bases for the protection of photoaging caused by BL irradiation. (c) 2023 The Authors. Published by Elsevier B.V. on behalf of Japanese Society for Investigative Dermatology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).