Background: Severe eosinophilic asthma is frequently associated to chronic rhinosinusitis and nasal polyposis (CRSwNP) that contribute to poor asthma control. Mepolizumab is an anti-IL-5 monoclonal antibody, approved for the treatment of severe eosinophilic asthma. A limited number of studies have assessed the efficacy of mepolizumab on CRSwNP in severe asthmatics. We aim to evaluate the efficacy of mepolizumab on sino-nasal symptoms, polyp growth and asthma control in severe eosinophilic asthma patients with CRSwNP in real life. Methods: In this study 44 severe eosinophilic asthma patients with CRSwNP were treated with mepolizumab (100 mg q4w) for 1 year. The following outcomes were assessed before (T0), after 6 (T6) and 12 months (T12) of treatment: sino/nasal outcome test (SNOT-22), Total Endoscopic Nasal Polyp Score (TENPS), %FEV1 (FEV1/FEV1 predicted) and Asthma control test (ACT). Blood eosinophil count, exhaled nitric oxide (FENO) and prednisone intake were measured. In a subgroup of patients, nasal cytology was performed before (T0), after 6 (T6) and after 12 months (T12) of treatment with mepolizumab. Results: We reported a significant reduction of SNOT-22 [from 51.5 ± 21.2 at baseline (T0) to 31.70 ± 17.36 at T6 and 29.7 ± 21.5 at T12 (T0–T12 p < 0.001)] and a decrease of TENPS (from 2.88 ± 3.07 to 1.70 ± 2.37 and 1.77 ± 2.56 at T0, T6 and T12, respectively, T0–T12 p = 0.99). A significant improvement of %FEV₁, ACT and a decrease in blood eosinophils and mean prednisone intake were also reported. No statistically significant decreasing trend was measured for FENO. Nasal cytology findings suggest a significant reduction of eosinophil percentage following mepolizumab treatment (from 16.8 ± 7.2% to 3.6 ± 6.2% and 0.8 ± 2.4% at T0, T6 and T12 respectively, T0 to T12: p < 0.001). Conclusions: Mepolizumab improves sino-nasal and asthma symptoms and reduces polyp growth in patients with severe eosinophilic asthma and concomitant CRSwNP in real life. The reviews of this paper are available via the supplemental material section.

Nitric oxide (NO) is a short-lived gas molecule which has been studied for its role as a signaling molecule in the vasculature and later, in a broader view, as a cellular messenger in many other biological processes such as immunity and inflammation, cell survival, apoptosis, and aging. Fractional exhaled nitric oxide (FeNO) is a convenient, easy-to-obtain, and non-invasive method for assessing active, mainly Th2-driven, airway inflammation, which is sensitive to treatment with standard anti-inflammatory therapy. Consequently, FeNO serves as a valued tool to aid the diagnosis and monitoring of several asthma phenotypes. More recently, FeNO has been evaluated in several other respiratory and/or immunological conditions, including allergic rhinitis, chronic rhinosinusitis with/without nasal polyps, atopic dermatitis, eosinophilic esophagitis, and food allergy. In this review, we aim to provide an extensive overview of the current state of knowledge about FeNO as a biomarker in type 2 inflammation, outlining past and recent data on the application of its measurement in patients affected by a broad variety of atopic/allergic disorders.