Exhaled Nitric Oxide Levels and Airway Responsiveness to Adenosine 5′-Monophosphate in Subjects with Nasal Polyposis

Abstract

Background:It is widely appreciated that asthma is an inflammatory disease of the airways associated with airway hyperresponsiveness, and that nasal polyposis and asthma are related diseases. The objective of this study was to determine differences in exhaled nitric oxide (ENO) levels and airway responsiveness to adenosine 5′-monophosphate (AMP) between nonasthmatic patients with nasal polyposis and healthy controls. Methods: Twenty patients without asthma with nasal polyposis and 16 healthy control subjects were enrolled in the study. Participants were challenged with increasing concentrations of AMP and methacholine. ENO was measured with the single-exhalation method. Results: Bronchoconstriction in response to AMP was detected in 7 (35%) subjects with nasal polyposis. The geometric mean (95% CI) of ENO for subjects with nasal polyposis was 33.1 parts per billion (ppb) (24.0–45.7 ppb) compared with 12.3 ppb (8.5–18.2 ppb) for the healthy controls (p = 0.0002). ENO values were significantly higher in atopic than in nonatopic subjects with nasal polyposis [51.3 ppb (32.3–83.2 ppb) vs. 24.5 ppb (16.2–37.1 ppb), p = 0.02]. Nonatopic subjects with nasal polyposis also had higher concentrations of ENO than healthy control subjects (p = 0.016). Conclusions: Inhaled AMP causes airway narrowing in a significantly higher proportion of nonasthmatic subjects with nasal polyposis than in healthy controls. Furthermore, increased concentrations of ENO are detected in atopic and nonatopic subjects with nasal polyposis. These results suggest that bronchial inflammation is present in nonasthmatic subjects with nasal polyposis.

Nitric Oxide: A Promising Methodological Approach in Airway Diseases

“…Hence, it would seem likely that higher epithelial iNOS levels in nasal polyposis would be associated with higher nasal NO levels by upregulation. However, interestingly in these patients, nasal NO levels were lower compared to controls or to individuals with uncomplicated allergic rhinitis [70,71,72,73] and exhaled NO was increased, even in non-atopic patients [72,74]. In patients with bronchiectasis, nasal NO was lower in CRS with nasal polyposis than in CRS without nasal polyposis, and inversely correlated with the occupancy of the ostiomeatal complex by CT scans in patients with nasal polyps [71].…”

Nitric oxide evaluation in upper and lower respiratory tracts in nasal polyposis

“…Additional results obtained in an additional subgroup of patients treated surgically. In 21 patients [six women, mean age 51 (44-55) years], nasal NO was measured 4 [3][4][5][6][7] years after surgery (functional endoscopic sinus surgery, as described previously [23]). A statistical rela-tionship was still evidenced between nasal NO and CT score (r = À 0.63, P = 0.013).…”

“…Nasal nitric oxide (NO) fraction is reduced in nasal polyposis (NP) and may constitute an objective and noninvasive assessment of NP severity [1][2][3]. In contrast, exhaled NO is increased, even in non-atopic patients with NP [4]. Explanations for such a discrepancy between upper and lower airways, sharing a similar epithelium (the main source of NO in the gas phase), are lacking.…”

AMP challenge induces a decrease in FENO in asthmatic subjects modulated by nedocromil

“…Adenosine‐5′‐monophosphate (AMP) acts as an indirect bronchoconstrictor, causing mast cell degranulation and release of pro‐inflammatory mediators. Inhalation of AMP has been shown to decrease FE NO levels in one study, but only in association with bronchoconstriction [6,10]. Nedocromil sodium inhibits histamine release from mast cells and prior inhalation has been shown to reduce bronchial hyper‐responsiveness to AMP in asthmatic subjects [11,12].…”