Effects of leukotriene D4 nasal challenge on bronchial responsiveness and inflammation in asthmatic patients with allergic rhinitis.

BACKGROUND: In asthmatic patients with allergic rhinitis (AR), increased cysteinyl leukotrienes (CysLTs) production in the secretion of nasal mucosa has been associated with greater bronchial hyperresponsiveness (BHR) after nasal allergen challenge. However, the role of CysLTs in eliciting BHR after nasal allergen challenge has not been evaluated. The aim of this study is to evaluate the effect of LTD4 nasal challenge on BHR and inflammation in asthmatic patients with AR.

METHODS: In this self-controlled study, fifteen eligible consecutively recruited subjects underwent methacholine (Mch) bronchial provocation test before and 30 minutes after LTD4 nasal provocation test. The cumulative concentration of LTD4 inducing a 60% increase in nasal airway resistance (PC60NAR) was calculated. The mean values of cumulative doses inducing a 20% decrease in forced expiratory flow in one second (PD20FEV1) for Mch before and after nasal challenge were compared. Fractional exhaled nitric oxide (FeNO), differential inflammatory cell counts in nasal lavage and induced sputum before and after nasal challenge were compared.

RESULTS: House dust mites were the major allergens accounting for 10/15 (66.7%) of asthmatic patients with AR. The PC60NAR for LT was (8.39±3.48)×10(-3) mg·mL(-1). The PD20FEV1 before and after nasal challenge was 3.05±3.81 and 2.70±3.81 µmol, respectively (P=0.45). The percentages of eosinophils were (38.36±23.14)% and (45.70±24.86)% in nasal lavage, and (17.51±11.05)% and (24.29±16.52)% in induced sputum before and 24 hours after nasal challenge. The neutrophil counts were (60.64±23.14)% and (53.30±24.46)% in nasal lavage, and (53.83±23.27)% and (56.19±22.28)% in induced sputum before and 24 hours after nasal challenge. The values of FeNO were 40 [35] and 43 [30] ppb before and 24 hours after nasal challenge. No severe adverse effects were reported during the tests.

CONCLUSIONS: Although most asthmatic patients with AR were sensitive to LTD4 nasal challenge, LTD4 nasal provocation tests do not confer any major effect on BHR. LTD4 might not play a vital role in eliciting bronchial responsiveness induced by nasal allergen challenge.