Osteopontin as a Novel Biomarker in Distinguishing Chronic Rhinosinusitis with Nasal Polyp Endotypes and Predicting Disease Severity

Introduction: The objective of this study was to ascertain the predictive value of osteopontin (OPN), a cytokine with pro-inflammatory properties implicated in inflammatory and allergic conditions, in nasal secretions for the identification of chronic rhinosinusitis with nasal polyp (CRSwNP) endotypes and the assessment of disease severity. Methods: A cohort comprising 81 individuals diagnosed with CRSwNP was enrolled, which included 37 subjects with the non-eosinophilic CRSwNP and 44 subjects with the eosinophilic CRSwNP (eCRSwNP), alongside 32 healthy controls (HCs). Nasal secretions and tissue samples were collected from all participants. The quantification of OPN in these samples was conducted using ELISA and immunohistochemistry. Nasal fractional exhaled nitric oxide levels were determined with the Nano Coulomb Breath Analyzer. The diagnostic efficacy of OPN levels in distinguishing eCRSwNP was assessed using the receiver operating characteristic (ROC) curve, while Pearson correlation analysis was employed to evaluate the correlation between OPN levels and disease severity indicators. Results: Concentrations of OPN in nasal secretions were found to be elevated in CRSwNP patients compared to the HC group and significantly higher in patients with eCRSwNP. A positive correlation was identified between OPN levels in nasal secretions and peripheral blood eosinophil counts and percentages, and tissue eosinophil counts, as well as the Visual Analog Scale (VAS) score, Lund-Mackay score, and Lund-Kennedy score. The ROC analysis demonstrated that the OPN level in nasal secretions possesses a robust discriminatory capacity for eCRSwNP, with a cutoff value of 121.05 ng/mL. Furthermore, the OPN concentration was determined to be a more precise predictor of the VAS score, Lund-Mackay score, and Lund-Kennedy score than the CRSwNP endotypes. Conclusion: The findings of this study indicate that OPN is differentially expressed in the nasal secretions of eCRSwNP patients and correlates with eosinophilic inflammation. The presence of OPN in nasal secretions emerges as a novel and potentially valuable biomarker for the differentiation of CRSwNP endotypes and the prognostication of disease severity.