LC-MS/MS Quantification and Comparative Profiling of Stratum Corneum Ceramides in Human Normal and Dry Skin Subtypes

Background: Ceramide (Cer) dysregulation in content and composition is linked to various skin conditions, particularly sensitive and dry skin. Existing ceramide quantification methods often lack efficiency, sensitivity, or comprehensive analytical capabilities. This study aimed to adopt an optimized LC-MS/MS platform to ensure the acquisition of reliable and accurate ceramide quantitative data, thereby providing robust methodological support for an in-depth investigation of the differences in ceramide profiles among different dry skin subtypes. Methods: Stratum corneum samples were collected via tape stripping from 93 adult female volunteers, who were stratified into sensitive dry skin, non-sensitive dry skin, and normal skin groups based on clinical assessments. Cer metabolomics was analyzed via targeted metabolomics using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results: Quantitative analysis of ceramide content in different groups revealed significantly elevated levels of ultra-long-chain ceramides and the atypical Cer (d17:1/24:0) in the SD group, alongside relatively lower levels of shorter-chain ceramides. The NSD group, in contrast, was predominantly enriched in shorter-chain ceramides. Statistical analysis showed statistically significant differences in the levels of Cer (d18:1/24:0), Cer (d18:1/24:1), and Cer (d17:1/24:0) between the SD group and the N group. The UPLC-MS/MS method exhibits a wide linear range and high recovery. Conclusions: This method offers a reliable tool for the quantitative analysis of ceramides in dermatological, physiological, and pathological research. The findings not only underscore the profound heterogeneity in lipid metabolism underlying different dry skin subtypes but also provide a molecular rationale linking aberrant ceramide chain lengths to compromised barrier integrity and heightened inflammatory susceptibility. The partially validated analytical platform and the specific ceramide signatures revealed herein offer valuable tools and insights for advancing the mechanistic understanding, diagnosis, and targeted intervention of sensitive dry skin.