Expressions Of IL-13and IL-13Rα2in Eosinophilic Chronic Rhinosinusitis With Nasal Polyps And Clinical Implications

Objectives/Hypothesis: Chronic rhinosinusitis (CRS) is a common disease and it iscurrently classified into two types based on presence or absence of nasal polyps, CRSwith nasal polyps (CRSwNP) and CRS without nasal polyps (CRSsNP). There is apredominant tissue eosinophil infiltration in some CRS, prominently in CRSwNP, andthese cases can be classified as eosinophilic CRS (ECRS). There are significantdifferences in clinical characteristics, underly pathogenic mechanisms and treatmentoutcomes between ECRS and non-eosinophilic (non-ECRS). ECRS is a subtype ofrecalcitrant CRS, having worse disease severity and poorer treatment outcomecompared to non-ECRS. Although intensive investigations have been performed, theetiology and pathogenesis of CRS remain controversial, and also underlyingmechanism of CRS is not fully understood. This study aims to investigate clinicalfeatures, IL-13and IL-13Rα2expressions and underlying mechanisms in ECRSwNP.Methods: A total of60consecutive adult patients with CRSwNP underwentendoscopic sinus surgery (ESS) was included in this study. CRSwNP was diagnosedaccording to the diagnostic criteria determined in the current clinical practiceguidelines. Based on postoperative histopathological examination and nasal polyptissue eosinophil count, ECRSwNP was determined as the average eosinophil countwas more than5eosinophils per high power field (HPF) and non-ECRSwNP as thecount was5eosinophils or less per HPF. IL-13and IL-13Rα2expressions in polyptissues were examined with immunohistochemistry. All patients were evaluated beforeESS for the severities of specific symptoms using VAS; the severities of nasal polypswere scored with endoscopic examination; the diseases of individual sinuses on CT were assessed; and blood eosinophil count and percent were measured.Results: The60patients were divided into two groups,27patients (20males and7females, with a mean age of46.9years) in ECRSwNP group and33patients (24malesand9females, with a mean age of40.3years) in non-ECRSwNP group. There was nodifference in age and sex between two groups (p>0.05). The patients with ECRSwNPor non-ECRSwNP had similar severities and duration of symptoms (p>0.05). Howevercompared to the patients with non-ECRSwNP, the patients with ECRSwNPdemonstrated a higher mean score of nasal polyps (3.6vs2.1, p<0.01), with a higherincidence of bilateral polyps (92.6%vs39.4%, p<0.01) and a higher score of diseaseseverity on CT (14.4vs9.6, p<0.01). And also compared to patients withnon-ECRSwNP, the patients with ECRSwNP had the increased blood eosinophil count(0.44vs0.21×109/L, p<0.01) or percent (6.49%vs3.42%. p<0.01) and the increasedtissue eosinophil count (33.9vs0.82cells/HPF, p<0.01). There was a closed relationbetween tissue eosinophil count and blood eosinophil count (r=0.683, p<0.01) orpercent (r=0.631, p<0.01) in ECRSwNP, but not in non-ECRSwNP.Immunohistamical analysis showed the expressions of IL-13and IL-13Rα2increasedsignificantly, in ECRSwNP when compared to non-ECRSwNP (p<0.01), with asignificant correlation between IL-13and IL-13Rα2expressions in ECRSwNP(r=0.483, p<0.05).Conclusion: CRSwNP can be classified into two subtypes of ECRSwNP andnon-ECRSwNP based on tissue eosinophil infiltration. ECRSwNP differs fromnon-ECRSwNP in clinical and histoimmunological characteristics. Increased bloodeosinophil count or percent can be used as a predictor for ECRSwNP. It is indicated thatIL-13and IL-13Rα2are associated closely with pathogenesis of ECRSwNP. SubtypingCRSwNP and studying for underly mechanism can be helpful to make treatmentstragety for CRSwNP.