Late Breaking Abstract - Secretory phospholipase A2-IIA in lung allografts: association with bile acid aspiration, bacteria and inflammatory mediators.

<bold>Introduction:</bold> Secretory phospholipase A2-IIA (sPLA2-IIA) is increased in inflammatory lung diseases. In lung transplant recipients (LTRs), bile acid (BA) aspiration predicts poor outcomes. We sought to study sPLA2-IIA in LTR airways and its relationship with BA, bacteria and inflammatory mediators. <bold>Methods:</bold> Bronchoalveolar lavage (BAL) and large airway bronchial wash (LABW) were prospectively collected from 138 LTRs at the 3-month post-transplant surveillance bronchoscopy and assayed for sPLA2-IIA by ELISA. LABW BA were tested by tandem mass spectrometry and inflammatory mediators by 48-multiplex. BAL microbiology was monitored. Non-parametric statistical analysis was performed. <bold>Results:</bold> sPLA2-IIA was quantifiable in 85% of samples, BAL median 376.6 pg/ml (IQR: 37.69-1760), LABW 1797 pg/ml (350-3998). BAL and LABW sPLA2-IIA levels directly correlated (Spearman r=0.66, p<0.0001). sPLA2-IIA correlated with total BA levels (r=0.33 p=0.0002). Samples with BA in upper tertile showed greater sPLA2-IIA: 3160 pg/ml (1319-5051) vs 1440 pg/ml (236-3573) (Mann-Whitney p<0.005). BAL samples positive for bacteria had higher sPLA2-IIA (642.6 pg/ml; 130-3227) compared to negative samples (223.5 pg/ml; 15.65-1151) (p<0.005). sPLA2-IIA correlated with 85% of inflammatory mediators (p<0.05). <bold>Conclusion:</bold> sPLA2-IIA levels in LTR airways were comparable to those reported in inflammatory lung disorders. sPLA2-IIA independently correlated with aspirated BA and inflammatory mediators and associated with presence of bacteria. These original findings suggest that sPLA2-IIA in LTR airways may serve as a marker of aspiration and infection, and support further investigation.