Analysis on the difference of skin surface lipids during blue light therapy for acne by lipidomics

Acne is a chronic inflammatory skin disease of the sebaceous glands of the hair follicles, caused by a variety of factors and tends to recur, causing skin damage and psychological stress to patients. Blue light (415nm) is a popular physical therapy for acne, however, studies on the effects of blue light on skin surface lipids (SSL) have not been exhaustively reported. So, we want to investigate the difference in SSL before and after acne treatment with blue light and to reveal the potential mechanism of acne treatment with blue light from the lipid level. SSL samples were collected and physiological indicators (moisture content, transepidermal water loss (TEWL), sebum content and pH) were measured. By using ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) with multivariate data analysis methods to obtain specific information on the lipid composition. Analysis of the physiological index data showed a significant increase in moisture content (p = 0.042), pH (p = 0.000) and a significant decrease in sebum content(p = 0.008) in the after treatment area (AT group), while there was no significant change in TEWL values. A total of 2398 lipids were detected by lipidomics analysis and 25 differential lipids were screened. Triradylglycerols (TGs), isoprenoids and hopanoids being the potential differential lipids. Among the lipids associated with the skin barrier, only monounsaturated fatty acids (MUFA) (p = 0.045) were significantly increased. This study revealed significant changes in SSL after blue light treatment for acne, suggesting that blue light exposure may cause changes in the relative lipid content and redistribution of lipid components, and that whether it damages the skin barrier requires further study.