Type 2 Inflammatory Shift in Chronic Rhinosinusitis During 2007-2018 in Belgium

Chronic rhinosinusitis (CRS) is a heterogenic disease with different inflammatory patterns depending on the presence (CRSwNP) or absence (CRSsNP) of polyps and geographical location. A shift toward type 2 endotype has been seen in Asia. We aim to investigate whether there has been type 2 shift in Belgium and to further endotype CRS based on clinical markers.

Prospective descriptive study.

Four hundred and thirty eight patients with CRS undergoing sinus surgery at Ghent University Hospital between 2007 and 2018 were included and stratified based on phenotype, comorbidities, inflammatory markers in tissue, and two different time points of surgery. Tissue samples from surgery were analyzed for type 2 markers. In a subgroup of CRSwNP blood eosinophils (EBC) was available.

There was an increase in type 2 inflammatory markers in the latter group versus the earlier, in non-asthmatic, non-allergic CRS patients regardless of phenotype. The proportion of IL-5+ patients was elevated in the latter group in CRSwNP. Inflammatory markers and comorbidities differ between IL-5+ CRSsNP and CRSwNP subjects, no difference was seen in IL-5- CRS. EBC can together with information on comorbidities help identify type 2 CRSwNP in a clinical setting.

There is a shift toward type 2 inflammation within the CRS population over recent 8 years also in Belgium. This shift implies that we expect to see more cases of severe and difficult to treat CRS in the future. Polyp formation is not directly linked to the presence or concentrations of type 2 inflammatory markers. Clinical parameters and EBC > 300 cells/μL can be used to identify type 2 CRSwNP.

3. Laryngoscope, 131:E1408-E1414, 2021.