Environmental Risks and Sphingolipid Signatures in Adult Asthma and Its Phenotypic Clusters: A Multi-Center Exploratory Study

Abstract

Background: Adult asthma is phenotypically heterogeneous with unclear etiology. We aimed to evaluate the potential contribution of environmental exposure and its ensuing response to asthma and its heterogeneity. Methods: Environmental risk was evaluated by assessing the records of National Health Insurance Research database (NHIRD) and residence-based air pollution [PM2.5 and PM2.5-bound polycyclic aromatic hydrocarbons (PAHs)], integrating biomonitoring analysis of environmental pollutants, inflammatory markers and sphingolipid metabolites in case-control populations with mass spectrometry and ELISA. Phenotypic clustering was evaluated by t-SNE integrating 18 clinical and demographic variables. Findings: In the NHIRD dataset, a modest increase in the relative risk with time-lag effect for emergency (N=209,837) and outpatient visits (N=638,538) was observed with increasing levels of PM2.5 and PAHs. Biomonitoring analysis revealed a panel of metals and organic pollutants, particularly metal Ni and PAH originated from multiple sources, posing a significant risk for current asthma and its severity, correlating with the level of oxidative stress markers, notably Ne-(hexanoyl)-lysine (HEL) as a marker of response in both cases and controls. Further, levels of circulating sphingosine-1-phosphate (S1P) and ceramide-1-phosphate (C1P) were found to discriminate asthma, correlating with the levels of exposure to PAH and metals, respectively, and both correlating with a panel of circulating inflammatory markers. Stratification of the combined datasets by 6 phenotypic clusters among 1,163 asthmatic subjects and those with comorbid T2DM revealed cluster-selective environmental risks and biosignatures. Interpretation: These results suggest the potential contribution of environmental factors, their ensuing oxidative stress and sphingolipid remodeling to adult asthma and its phenotypic heterogeneity. Funding Information: This work was supported, in part, by grants from National Health Research Institutes, Taiwan (EOPP10-014, EOSP07-014 and NHRI-102A1-PDCO-03010201) and Ministry of Health, Taiwan (EODOH01), National Science Council (NSC 102-2314-B-037-052), Ministry of Health (EODOH01), Ministry of Science and Technology (MOST 103-2320-B-110-001), and Academic Sinica (BM-102021170), Taiwan. Declaration of Interests: We declare no competing interests. Ethics Approval Statement: All eligible subjects were enrolled in the study after signing the informed consent approved by the respective recruitment hospitals.