余幸司

Abstract:

Alopecia areata (AA) in humans is a nonscarring hair loss characterized by an autoimmune response in the hair follicles. Collapse of anagen (growth phase) hair immune privilege is an essential prerequisite for development of AA. In an AA model mouse, plasmatocytoid dendritic cells (pDCs) play a significant role in inducing AA. Recent studies demonstrated that sleep disturbance and Western diet (rich in fat and defined sugars) are risk factors of hair loss (HL). This study investigates the effects and underlying pathomechanisms of blue LED lighting (BL) and WD feeding (WD) on hair loss in mice. Our results revealed that: (1) BL significantly induced hair loss; (2) both BL and WD upregulated Per2 expression in the hair follicles of HL areas; (3) BL, but not WD, significantly induced perifollicular pDCs infiltration in HL regions. These findings indicate that BL plays a critical role in collapsing hair immune privilege in this model. Furthermore, Fourier-transform infrared spectroscopy and imaging were employed in this study. Absorbance ratios of lipid to Amide ll, glycan to Amide ll, Amide lll to Amide ll (collagen) and C28/C22 values (inflammation) were measured at the hair loss sites. The relevance of these findings to the mechanisms of collapse hair immune privilege induced by blue light and Western diet will be discussed.

Keywords – hair loss, blue LED light, Western diet, FTIR, mechanisms

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