Pseudo Leukotrienes: Cysteinyl Leukotriene-like Agonists are Upregulated in Severe Asthma

Asthma is a chronic inflammatory airway disease in which cysteinyl leukotrienes (CysLTs) have long been regarded as one of the key mediators of pathology. We discovered that free radical-induced oxidation of arachidonic acid (AA) produces breakdown products that are structurally similar to CysLTs, which we refer to as pseudo leukotrienes (øLTs). This presentation will describe how an LC-MS/MS-based bioanalytical method was used to translate these signals into clinically informative cues/indicators of asthma severity. My talk will highlight a method development for measuring øLTs levels in human urine samples and mouse lung extracts, with an emphasis on careful data consideration/interpretation and analyte-specific recovery method that strengthen confidence in assessing the correlation between the øLTs levels and asthma severity. Another key case study will show how differences in extraction chemistry can influence the interpretation of the øLT panel. Because øLTs have different hydrophobicity, the initial reversed-phase solid phase extraction (SPE) method likely under-recovered one species, rendering the optimization to a mixed-mode SPE method that improved recovery and enhanced the analyte signal. Additionally, results of in vitro molecular biology assays support our hypothesis that øLTs could be the predominant CysLT receptor agonists that drive inflammation in asthma pathogenesis. Together, these findings illustrate a “signals to impact” framework in which robust bioanalysis reveals øLTs as previously unrecognized “unknown unknowns”, and they are promising non-invasive biomarkers in asthma that may also reshape the pathological mechanisms of many other CysLT-driven diseases.