Montelukast reduces inhaled chlorine triggered airway hyperresponsiveness and airway inflammation in the mouse.

BACKGROUND AND PURPOSE: Cysteinyl leukotrienes (CysLTs) are pro-inflammatory lipid mediators that exacerbate disease state in several asthma phenotypes including asthma induced by allergen, virus and exercise. However, the role of CysLTs in irritant-induced airway disease is not well characterized. The purpose of the current study was to investigate the effect of montelukast, a CysLT1 receptor antagonist, on parameters of irritant-induced asthma induced by inhalation of chlorine in the mouse.

EXPERIMENTAL APPROACH: BALB/c mice were exposed to chlorine in air (100 ppm, for 5 min). Montelukast (3 mg·kg-1 ) or the vehicle (1% methylcellulose) was administered 24 and 1 h prior to chlorine exposure and 1 h prior to outcome measurements. Twenty-four hours after exposure, responses to inhaled aerosolized methacholine, cell composition and an array of cytokines/chemokines in bronchoalveolar lavage (BAL) fluid were measured. Neutralizing antibodies against IL-6 and VEGF were administered prior to exposures.

KEY RESULTS: Montelukast reduced chlorine -induced airway hyperresponsiveness (AHR) to methacholine in the peripheral lung compartment as estimated from dynamic elastance, but not in large conducting airways. Montelukast treatment attenuated chlorine-induced macrophage influx, neutrophilia and eosinophilia in BAL fluid. Chlorine exposure increased VEGF, IL-6, the chemokines KC and CCL3 in BAL fluid. Montelukast treatment prevented chlorine-induced increases in VEGF and IL-6. Anti-IL-6 antibody inhibited chlorine-induced neutrophilia and reduced AHR.

CONCLUSIONS AND IMPLICATIONS: Pre-treatment with montelukast attenuated chlorine-induced neutrophilia and AHR in mice. These effects are mediated, in part, via IL-6.