Ceramide/sphingosine-1-phosphate imbalance is associated with distinct inflammatory phenotypes of uncontrolled asthma

Background: Asthma is associated with inflammatory dysregulation, but the underlying metabolic signatures are unclear. This study aimed to classify asthma inflammatory phenotypes based on cellular and metabolic features. Methods: To determine cellular and metabolic profiles, we assessed inflammatory cell markers using flow cytometry, sphingolipid (SL) metabolites using LC-MS/MS, and serum cytokines using ELISA. Targeted gene polymorphisms were determined to identify genetic predispositions related to the asthma inflammatory phenotype. Results: In total, 137 patients with asthma and 20 healthy controls (HCs) were enrolled. Distinct cellular and metabolic profiles were found between them; patients with asthma showed increased expressions of inflammatory cell markers and higher levels of SL metabolites compared to HCs (P <.05 for all). Cellular markers (CD66(+) neutrophils, platelet-adherent eosinophils) and SL metabolic markers (C16:0 and C24:0 ceramides) for uncontrolled asthma were also identified; higher levels were observed in uncontrolled asthma compared to controlled asthma (P <.05 for all). Asthmatics patients with higher levels of CD66(+) neutrophils had lower FEV1(%), higher ACQ (but lower AQLO) scores, and higher sphingosine and C16: 0 ceramide levels compared to those with low levels of CD66(+) neutrophils. Asthmatics patients with higher levels of platelet-adherent eosinophils had higher S1P levels compared to those with lower levels of platelet-adherent eosinophils. Patients carrying TT genotype of ORMDL3 h ad m ore CD66(+) neutrophils; those with AG/GG genotypes of SGMS1 exhibited higher platelet-adherent eosinophils. Conclusion: Patients with uncontrolled asthma possess distinct inflammatory phenotypes including increased CD66(+) neutrophils and platelet-adherent eosinophils, with an imbalanced ceramide/S1P rheostat, potentially involving ORMDL3 and SGMS1 gene polymorphisms. Ceramide/S1P synthesis could be targeted to control airway inflammation.