Contribution of Neurogenic and Allergic Ways to the Pathophysiology of Nonallergic Rhinitis

Abstract

Background: A neuroallergic interaction was reported in the pathogenesis of allergic rhinitis (AR), but the pathophysiology of nonallergic rhinitis (NAR) is poorly understood. We aimed to explore the contribution of neuroallergic mechanisms to the pathogenesis of NAR. Methods: Subjects were divided into three groups – NAR patients (n = 25), AR patients (n = 16) and the control group (n = 10) – and were assessed using the nasal provocation test (NPT) with house dust mite. Total symptom scores, nasal inspiratory peak flow and nasal lavage were performed before and after NPT. Nasal brushing and scraping was done after NPT. Results: NPT was positive in NAR (52%) and AR (100%) patients and negative in all controls. After NPT, total symptom scores increased in both rhinitis groups. Post-NPT values of nasal inspiratory peak flow decreased only in AR patients. NAR patients showed a similar inflammatory cell profile in the nasal smears to AR patients which was different in controls. There were more tryptase- and immunoglobulin E (IgE)-positive cells in the nasal mucosa of AR patients, and more substance-p-positive cells were observed in NAR patients compared with controls. However, IgE- and tryptase-positive cells in NAR patients and substance-p-positive cells in AR patients were detectable in nasal mucosa, but rarely in the controls. Comparing the values before and after NPT, tryptase significantly increased in the nasal lavages of AR and NAR patients, while house dust mite-specific IgE did not change. Conclusions: We showed the existence of a common pathophysiological mechanism with different contributions in AR and NAR. We conclude that the difference in dominance of neuroallergic ways may determine the major phenotype of rhinitis.