MS-based metabolite profiling reveals time-dependent skin biomarkers in UVB-irradiated mice

We observed clinical and histological changes, including increased transepidermal water loss, epidermal thickness, and inflammatory cells, and changes in collagen fibers in the skin of mice chronically exposed to ultraviolet (UV) B radiation for 12 weeks. By using ultra-performance liquid chromatography-quadrupole time-of-flight (TOF) mass spectrometry (MS), gas chromatography (TOF-MS), and NanoMate tandem-MS-based metabolite profiling, we identified amino acids, organic compounds, fatty acids, lipids, nucleosides, carbohydrates, lysophosphatidylcholines, lysophosphatidylethanolamines, urocanic acids, and ceramides (CERs) as candidate biomarkers of the histological changes in mouse skin following UVB irradiation for 6 and 12 weeks. cis-Urocanic acid and cholesterol showed the most dramatic increase and decrease at 6 and 12 weeks, respectively. In addition, the changes in skin primary metabolites and lysophospholipids induced by UVB exposure were generally greater at 12 weeks than at 6 weeks. The results from primary metabolite, lysophospholipid, and CER profiles suggest that prolonged chronic exposure to UVB light has a great effect on skin by altering numerous metabolites. A comprehensive MS-based metabolomic approach for determining regulatory metabolites in UV-induced skin will lead to a better understanding of the relationship between skin and UV.