Targeted Metabolomic Analysis of Signaling Metabolites

Metabolomic studies were performed using directed, non-targeted liquid chromatography-mass spectrometry (LC-MS) approaches to specifically capture and assay small polar “bioactive” metabolites. These were deemed to have a higher likelihood of interacting with cell surface receptors involved in signaling. These include free fatty acids, eicosanoids and oxylipins, bile acids, and fatty acid esters of hydroxy fatty acids, among hundreds of unidentified related metabolites [34 (link),35 (link)]. Metabolite levels are used as continuous traits with a mean of 0 and standard deviation of 1. Identified metabolites were confirmed through internal standards.