Untargeted metabolomic profiling identifies disease-specific and outcome-related signatures in chronic rhinosinusitis

Background: Although metabolomics provides novel insights into disease mechanisms and biomarkers, the metabolic alterations in local tissues affected by chronic rhinosinusitis (CRS) are unknown. Objective: This study aimed to determine the metabolomic profiles of sinonasal tissues associated with different types of CRS and their treatment outcomes. Methods: Untargeted metabolomic profiling was performed on sinonasal tissues obtained from patients with eosinophilic CRS with nasal polyps (CRSwNP), noneosinophilic CRSwNP or CRS without nasal polyps (CRSsNP), and controls. The messenger RNA (mRNA) levels of inflammatory cytokines in nasal tissues were detected by quantitative real-time reverse transcriptase PCR. Nasal polyp tissues were cultured ex vivo and treated with glutathione. Results: Distinct metabolomic profiles were observed for the CRS subtypes. Eosinophilic CRSwNP had profoundly enhanced unsaturated fatty acid oxidization, which correlated with mucosal eosinophil numbers and IL-5 mRNA levels. Noneosinophilic CRSwNP was characterized by uric acid accumulation. Increased uric acid levels were positively correlated with mucosal neutrophil numbers and IFN-gamma, IL-17A, IL-1 beta, and IL-8 mRNA levels. Disrupted purine metabolism was specifically detected in CRSsNP. Reduced levels of amino acid metabolites were found in eosinophilic CRSwNP and CRSsNP, and were inversely associated with mucosal total inflammatory cell numbers and inflammatory cytokines. Compared to non-difficult-to-treat CRS, difficult-to-treat CRS had higher glutathione disulfide levels, which were positively correlated with IL-8 mRNA levels. Glutathione treatment reduced IL-8 mRNA expression in cultured nasal polyp tissues. Conclusions: Specific metabolic signatures are associated with different types of CRS, inflammatory patterns, and disease outcomes, which may provide novel insights into pathophysiologic mechanisms, subtype-specific biomarkers, and treatment targets of CRS.