Peripheral blood neutrophils and upregulated surface expression of interleukin-17 and CD177 in patients with bronchial asthma: an association with fungal allergy

Abstract

BackgroundAsthma is a prevalent debilitating airway disease, with a tremendous effect worldwide. Fungi and their spores are identified as major culprits in allergic asthma (AA) etiology. Peripheral blood neutrophils and interleukin 17 (IL-17), which are considered crucial players in both bronchial asthma and host defense mechanisms against fungi, increase concomitantly; moreover, certain subsets of neutrophils express and even release IL-17.ObjectivesIn this study, we sought to determine the peripheral frequency of certain neutrophil subpopulations, expressing both CD177 and IL-17, among AA patients, particularly those with fungal allergy.MethodsThis observational study comprised 40 patients with AA (age range 19–60 years) and 20 age-matched and sex-matched healthy controls (age range 20–55 years). All patients had positive allergy skin prick test results, and accordingly, they were further subdivided into two groups (18 reactive to fungal allergens and 22 to other aeroallergens). The frequency of IL-17+CD177+ neutrophils in the peripheral blood was assessed by flow cytometry in all studied participants.ResultsThe authors observed significantly increased frequency of circulating IL-17+CD177+ neutrophils among AA patients (especially mild to moderate cases) compared with healthy controls (43.3±13.9 vs 15.3±4.8). On the contrary, and surprisingly, patients with fungal allergy and those without did not show any difference with respect to this neutrophil subpopulation (44.6±14.4 vs 42.2±13.7).ConclusionDespite limited sample size, we reported elevated IL-17+CD177+ neutrophil proportion in all AA, regardless of fungal aeroallergenicity. This observation points to a role played by this neutrophil subpopulation in asthma pathophysiology, especially the allergic phenotype, and hopefully offer a new therapeutic approach in asthma management.