Causal relationship between lipidome and acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS), with high morbidity and mortality, is a common clinical syndrome of acute respiratory failure caused by diffuse lung inflammation and edema. ARDS can precipitate in various ways. The complex pathophysiology of ARDS involves the activation and dysregulation of multiple metabolisms and immune responses. Using summary-level data from a genome-wide association study (GWAS), a two-sample Mendelian randomization (MR) analysis of 179 genetically predicted lipid species and ARDS (375 cases, 406,518 controls) was performed and validated in plasma and pulmonary edema fluid from 24 patients. Furthermore, we used a two-step MR to quantify the effect of immune cell-mediated lipids on ARDS. We identified 8 lipids (Cholesterol, Phosphatidylcholine (14:0_16:0), Phosphatidylcholine (16:0_20:5), Phosphatidylcholine (18:0_18:2), Phosphatidylethanolamine (18:1_18:1), Triacylglycerol (51:2), Triacylglycerol (52:4), and Triacylglycerol (54:3) ) associated with ARDS. The proportions of genetically-predicted lipids mediated by the four types of immune cells were determined. Sensitivity analysis did not reveal any obvious pleiotropy or heterogeneity. Our study demonstrates the power of multivariate genetic analysis in correlated lipidomic data and reveals genetic links between ARDS and lipid species beyond standard lipids.