Lipid Atlas of Keratinocytes and Betulin Effects on its Lipidome Profiled by Comprehensive UHPLC-MS/MS with Data Independent Acquisition Using Targeted Data Processing

Betulin is a pentacyclic triterpene with demonstrated healing properties in mid-dermal wounds. A few earlier studies have provided insights into the wound healing effects on the molecular level. However, there are still questions left on the molecular targets of betulin. Therefore, a pharmacolipidomics analysis of betulin is undertaken in human immortalized keratinocytes to monitor alterations in the lipid profiles induced by treatment with betulin. For this purpose, lipid extracts of keratinocytes treated with betulin and untreated controls are comprehensively analyzed by an untargeted UHPLC-ESI-QTOF-MS/MS lipidomics profiling workflow using data-independent acquisition. Targeted data processing allows the identification of 611 lipid species from 21 different lipid classes. Statistical analysis of the identified lipids shows significant changes in 440 lipid species that can be described as downregulation of cholesteryl esters and triacylglycerides and upregulation of glycerophospholipids, sphingolipids, and diacylglycerides. Additionally, some other signals corresponding to triterpenes are found in the betulin group and suggested that betulin is incorporated (in the membrane) and metabolized in keratinocytes.