Introduction:Chronic rhinosinusitis with nasal polyps (CRSwNP) is linked to type 2 inflammation in over 80% of the Western population. Biological agents are used for severe, uncontrolled cases when standard therapy fails. Neutrophils, associated with type 1 inflammation, may contribute to chronicity and treatment resistance in CRSwNP.

Objective:To assess the impact of nasal tissue neutrophilia on dupilumab response in severe uncontrolled CRSwNP.

Methodology:A retrospective study with 23 CRSwNP patients on dupilumab and intranasal corticosteroids, following prior nasosinusal surgery, assessed at baseline and 6 months. Systemic eosinophilia, tissue eosinophilia and neutrophilia were recorded. Scores evaluated included Sino-nasal Outcome Test (SNOT-22), Visual Analogue Scale (VAS) total symptoms, Nasal Polyp Score (SPN), Barcelona Smell Test 24 (BAST-24), Nasal Congestion Score (SCN), and Smell Loss Score (SPO). Python, pandas, and SciPy were used for analysis.

Results:The sample included 23 patients (12 male, 11 female), median age 57. Mean tissue neutrophil count was 2±2.3, ranging from 0 to 8 per high-power field. A significant correlation was found between tissue neutrophilia and SPO variation (r=0.464, p=0.034). Non-significant trends were noted for the other variables. Direct correlations were found between tissue eosinophilia and neutrophilia (r=0.595, p=0.004) and between tissue neutrophilia and peripheral IgE (r=0.548, p=0.010). Linear regression, controlling for eosinophils and neutrophils, showed a significant association between eosinophil count and BAST-24 variation (R²=0.301, p=0.010).

Conclusion:Higher neutrophil levels appear linked to dupilumab resistance, with less improvement in SPO. Small sample size limits reliability, warranting further studies

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