Montelukast during primary infection prevents airway hyperresponsiveness and inflammation after reinfection with respiratory syncytial virus

Abstract

Rationale: Respiratory syncytial virus (RSV) bronchiolitis in infants may be followed by the development of asthma-like symptoms. Age at first infection dictates consequences upon reinfection. Reinfection of mice initially exposed as neonates to RSV enhanced development of airway hyperresponsiveness (AHR), eosinophilic inflammation, and mucus hyperproduction. RSV lower respiratory tract disease is associated with activation of the leukotriene pathway.

Objectives: To determine the effects of montelukast (MK), a cysteinyl leukotriene (cysLT) receptor antagonist, in primary and secondary RSV-infected newborn and adult mice.

Methods: BALB/c mice were infected with RSV at 1 week (neonate) or 6 to 8 weeks (adult) of age and reinfected 5 weeks later. MK was administered 1 day before the initial infection and through Day 6 after infection. Seven days after primary or secondary infection, airway function was assessed by lung resistance to increasing doses of inhaled methacholine; lung inflammation, goblet cell metaplasia, and cytokine levels in bronchoalveolar lavage fluid were monitored.

Measurements and main results: RSV infection induced cysLT release in bronchoalveolar lavage fluid. MK decreased RSV-induced AHR, airway inflammation, and increased IFN-gamma production in primary infected adult and neonatal mice. MK, administered during initial infection of neonates but not during secondary infection, prevented subsequent enhancement of AHR, airway eosinophilia, and mucus hyperproduction upon reinfection.

Conclusions: MK attenuated the initial responses to primary RSV infection in both age groups and altered the consequences of RSV reinfection in mice initially infected as neonates. These data support an important role for cysLT in RSV-induced AHR and inflammation.

Figure 1.

Effect of montelukast (MK) treatment on airway responsiveness to primary respiratory syncytial virus (RSV)-infected adult mice. BALB/c mice (6–8 wk old) were inoculated with RSV (n = 6 per group). MK at 30 mg/kg was administered 1 day before RSV infection and through 6 days after infection. Airway responsiveness to (A) inhaled methacholine, (B) bronchoalveolar lavage cellularity, and (C) bronchoalveolar lavage fluid IFN-γ levels were assessed on Day 7 after infection. (D) Lung viral titers were examined on Days 2, 4, and 7 after RSV infection. The data are expressed as mean ± SEM. *P < 0.05; **P < 0.01 compared with control or RSV-MK to RSV. Eos = eosinophil; Lym = lymphocyte; Mac = macrophage; MCh = methacholine; Neu = neutrophil; PFU = plaque-forming units; Rl = lung resistance.

Figure 2.

Effect of montelukast (MK) treatment on airway responsiveness and inflammation in primary respiratory syncytial virus (RSV)-infected neonatal mice. BALB/c mice were inoculated as newborns (<1 wk of age) with RSV (n = 6 per group). MK (30 mg/kg) was administered 1 day before RSV infection and through 6 days after infection. Airway responsiveness (A) to inhaled methacholine, (B) bronchoalveolar lavage cellularity, and (C) bronchoalveolar lavage fluid (BAL) IFN-γ levels were assessed on Day 7 after infection. (D) Lung viral titers were examined on Days 2, 4, and 7 after RSV infection. The data are expressed as mean ± SEM. *P < 0.05; **P < 0.01 compared with control or RSV-MK to RSV. MCh = methacholine; PFU = plaque-forming units; Rl = lung resistance.

Figure 3.

Effect of montelukast (MK) treatment on airway responsiveness and inflammation on reinfection of newborn mice. Newborn BALB/c mice were treated with MK administered during primary neonatal respiratory syncytial virus (RSV) infection. Airway responsiveness to (A) inhaled methacholine, (B) bronchoalveolar lavage (BAL) cellularity, (C) lung histopathology, (D) BAL fluid cytokine levels, (E) in vitro cytokine production by peribronchial lymph node mononuclear cells after RSV stimulation, and (F) BAL fluid cysLT levels on Day 7 after secondary RSV infection. The data are expressed as mean ± SEM. *P < 0.05, **P < 0.01. MCh = methacholine; PBLN = peribronchial lymph node; Rl = lung resistance; 1°RSV = primary RSV infection; 2°RSV = secondary RSV infection.

Figure 4.

Effect of montelukast (MK) treatment during secondary infection on airway responsiveness and inflammation after reinfection of newborn mice. Newborn BALB/c mice were infected with respiratory syncytial virus (RSV) and reinfected with RSV 5 weeks later. MK was administered during secondary RSV infection. (A) Protocol. (B) Airway responsiveness to inhaled methacholine. (C) Bronchoalveolar lavage cellularity. (D) Bronchoalveolar lavage fluid cysLT levels on Day 7 after secondary RSV infection. The data are expressed as mean ± SEM. *P < 0.05. Mch = methacholine; Rl = lung resistance.