Original Articles: Rhinitis, Sinusitis, Upper Airway Diseases
Nasal mucosal expression of nitric oxide synthases in patients with allergic rhinitis and its relation to asthma

https://doi.org/10.1016/S1081-1206(10)60398-5Get rights and content

Background

Nitric oxide (NO) has contradictory roles in the pathophysiology of allergic inflammation in both allergic rhinitis (AR) and asthma. Small amounts of NO produced by constitutive NO synthase (NOS) is anti-inflammatory, whereas large amounts produced by inducible NOS (iNOS) are proinflammatory.

Objective

To investigate the difference in constitutive endothelial NOS (eNOS) and iNOS expression in nonallergic and allergic mucosa and the possible relation of this to the coexistence of asthma in seasonal AR.

Methods

Seventeen patients (10 women and 7 men) with seasonal AR and 9 nonallergic patients (5 women and 4 men) with nasal septum deviation were enrolled. Inferior turbinate nasal biopsy specimens were obtained in all. Levels of eNOS and iNOS expressed as immunohistochemical scores (HSCOREs) were determined immunohistochemically from the specimens.

Results

The mean ± SD HSCOREs for eNOS in patients with seasonal AR were not significantly different from those of the nonallergic controls (1.85 ± 0.78 vs 1.63 ± 0.54; P = .12). On the other hand, the mean ± SD HSCOREs for iNOS were significantly higher in patients with seasonal AR (1.75 ± 0.75 vs 0.71 ± 0.6; P = .004). Furthermore, although eNOS expression was not different between seasonal AR patients with and without asthma, the mean ± SD HSCOREs for iNOS were significantly higher in the patients with asthma (1.93 ± 0.78 vs 1.65 ± 0.55; P = .01).

Conclusion

Increased expression of iNOS might have a role in the development of allergic inflammation in upper and lower airways and in comorbidity of AR and asthma.

Section snippets

INTRODUCTION

Nitric oxide (NO) is a short-lived, lipophilic free radical that is synthesized from arginine by the action of NO synthase (NOS), which has 3 forms, including constitutive neuronal NOS (nNOS), inducible NOS (iNOS), and constitutive endothelial or epithelial NOS (eNOS). 1, 2, 3, 4 NO is found in higher concentrations in upper airways when compared with the lower airways in healthy individuals. 5 NO has contradictory roles in the pathophysiology of allergic inflammation in both allergic rhinitis

Participants and Study Design

Seventeen patients (10 women and 7 men) with seasonal AR were enrolled in this study along with 9 patients (5 women and 4 men) with nasal septum deviation as the nonallergic control group. Ethical concerns prohibited enrollment of a healthy control group in the study. In patients with seasonal AR, the mean ± SD age was 26.52 ± 5.91 years (age range, 19-37 years). Diagnosis of seasonal AR was based on history, physical examination, and skin testing. Allergic sensitization was demonstrated by

RESULTS

The expression of eNOS in patients with seasonal AR and nonallergic controls was similar. The HSCORE for eNOS in seasonal AR was 1.85 ± 0.78, whereas that in the nonallergic control was 1.63 ± 0.54 (P = .12) Figure 1, Figure 2. On the other hand, a significant difference was found between expressions of iNOS in the 2 groups. The HSCORE for iNOS in the seasonal AR group was 1.75 ± 0.75 and that in the nonallergic control group was 0.71 ± 0.6 (P = .004) Figure 3, Figure 4.

When patients with

DISCUSSION

NO is a short-lived, lipophilic free radical that activates guanylyl cyclase, which catalyzes the formation of guanosine monophosphate that has a role in smooth muscle relaxation, immune regulation, many physiologic organizations, and cell to cell communication. 15, 16 It has dual effects on airway: weak bronchodilation that might be beneficial and cytotoxicity and inflammation that are deleterious. 17 Furthermore, it suppresses T-cell proliferation and TH1 cell response, favoring TH2 response

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Disclosures: Authors have nothing to disclose.

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Copyright © 2008 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.