Circulating BAFF as novel biomarker in distinguishing chronic rhinosinusitis with nasal polyps endotypes and predicting postoperative recurrence

B cell-activating factor (BAFF) is a proinflammatory cytokine involved in inflammatory and allergic diseases, but its role in chronic rhinosinusitis with nasal polyps (CRSwNP) remains unclear. This study aims to explore the predictive value of circulating BAFF in CRSwNP endotypes and postoperative recurrence.We recruited 120 CRSwNP patients, including 68 non-eosinophilic CRSwNP (neCRSwNP) patients, 52 eosinophilic CRSwNP (CRSwNP) patients, and 60 healthy controls (HCs). Circulating BAFF levels of all participants were measured by enzyme-linked immunosorbent assay (ELISA), and receiver-operating characteristic (ROC) and logistic regression analyses were applied to assess the predictive ability of BAFF levels in distinguishing CRSwNP endotypes. All CRSwNP patients were followed for more than 3 years, and the predictive value of circulating BAFF for postoperative recurrence was evaluated.Serum BAFF levels were elevated in CRSwNP patients compared with the HCs (P < 0.01) and significantly higher in eCRSwNP patients. The increased serum BAFF concentrations positively correlated with blood eosinophil counts and percentages, tissue eosinophil counts, and serum total IgE (P < 0.05). The ROC curve showed that serum BAFF exhibited strong discriminative ability for eCRSwNP. Finally, 99 CRSwNP patients completed the follow-up schedule, 65 patients were classified into non-recurrence group and the other 34 patients were categorized into recurrence group. Serum BAFF levels were significantly higher in recurrence group than non-recurrence group (P < 0.001), and the ROC curve suggested a high predictive value of serum BAFF in predicting postoperative recurrence. Moreover, logistic regression and Kaplan-Meier curves showed that serum BAFF was an independent risk factor for postoperative recurrence (P < 0.05).Our data suggested that serum BAFF levels were upregulated in CRSwNP patients and correlated with mucosal eosinophil infiltration severity. Serum BAFF seemed to be a novel biomarker for preoperatively distinguishing CRSwNP endotypes and predicting postoperative recurrence.