Reduction of Eosinophilic Inflammation in the Airways: Conclusion

Prompt improvement of bronchoconstriction by CysLT1-receptor antagonists has been reported in asthma. In fact, bronchodilatory effect was observed several hours after treatment with CysLT1-receptor antagonists. In the present study, we found that treatment with montelukast resulted in significant increases in both morning and evening PEF compared with the baseline values. Because the number of patients evaluated in this study was small, significant difference in evening PEF was only observed between montelukast and placebo treatment at 4 weeks of treatment.
In this study, we also investigated the relationship between the increase in PEF and the decrease in sputum eosinophils before and after administration of montelukast and placebo. However, we failed to demonstrate a significant relationship, suggesting that the increase in PEF may be caused not only by the decrease in eosinophils in the airway. Therefore, we speculate that improvement of respiratory function may be induced by the wide variety of inhibitory actions of CysLTs-receptor antagonist such as bron-chodilatation. In addition, because the present study was neither designed nor powered to determine the correlation between clinical parameters and airway inflammation, further clinical trials will be needed to reach a definitive conclusion.
Airway hyperresponsiveness is a characteristic feature of asthma. Although several factors are involved in the pathophysiologic features of airway hyperresponsiveness, ongoing airway inflammation may play an important role in inducing, maintaining, and enhancing airway hyperresponsiveness Reading here In our study, treatment with montelukast significantly decreased eosinophils in induced sputum but did not alter airway responsiveness to histamine. In addition, a previous report also failed to show a significant improvement in airway responsiveness to methacho-line after 12 weeks of treatment with montelukast. These results suggest that although CysLT1 receptor antagonists have both bronchodilatory and antiinflammatory actions, airway responsiveness may be regulated mainly by factors other than CysLTs.
In conclusion, our study confirms that the CysLT1-receptor antagonist, montelukast, exerts both bronchodilatory and anti-inflammatory effects in patients with asthma.