Metabolomic profile perturbations of serum, lung, bronchoalveolar lavage fluid, spleen and feces in LPS-induced acute lung injury rats based on HPLC-ESI-QTOF-MS

Acute lung injury (ALI) is a clinically common and serious disease, underscoring the urgent need for clarification of its pathogenesis. According to traditional Chinese medicine (TCM) theories on the “lung–spleen–intestine axis” and its correlation with ALI, a high-performance liquid chromatography–quadrupole time-of-flight mass spectrometry (HPLC–QTOF-MS) metabolomic platform was applied to identify biomarkers from five bio-samples of control and model rats challenged with intratracheally administered lipopolysaccharide (LPS) based on multivariate mathematical statistical analysis. As a result, 19, 24, 24, 15 and 29 altered metabolites were identified in serum, lung, bronchoalveolar lavage fluid (BALF), spleen and feces samples, respectively. Metabolic pathway analysis showed that linoleic acid, sphingolipid, glycerophospholipid and bile acid metabolism pathways were mainly altered by ALI. Additionally, ROC curves were applied to assess the specificity and sensitivity of the biomarkers. ALI characteristic metabolomic spectra were then established to differentiate the control from the model group with a similarity discriminative threshold of 0.7. Additionally, to compare the metabolomic profiles of the five bio-samples and establish metabolic similarities and differences among them, correlation analysis was conducted in order to delineate an objective law of endogenous linkage along the lung–spleen–intestine axis. Therefore, this study provides insights into the mechanisms involved in ALI from a metabolomics perspective, which can be applied in characterization of the mechanism and early disease detection. Graphical abstract