Montelukast modulates lung CysLT1 receptor expression and eosinophilic inflammation in asthmatic mice

AIM: To determine the expressions of cysteinyl leukotriene receptors, CysLT(1) and CysLT(2), in airway eosinophilic inflammation of OVA-induced asthmatic mice and the modulation by montelukast, a CysLT(1) receptor antagonist. METHODS: Asthma model was induced by chronic exposure to ovalbumin (OVA) in C57BL/6 mice. The eosinophils in bronchoalveolar lavage (BAL) fluid and lung tissues were counted, IL-5 level in BAL fluid was measured, and CysLT(1) and CysLT(2) receptor mRNA expressions were detected by semi-quantitative RT-PCR. RESULTS: Montelukast (6 mg/kg, once per day for 20 d) significantly suppressed the increased eosinophils in BAL fluid and lung tissue, and increased IL-5 level in BAL fluid in OVA challenged mice. OVA challenge increased CysLT(1) but decreased CysLT(2) receptor mRNA expression. Montelukast inhibited the increased CysLT(1) but not the reduced CysLT(2) expression after OVA challenge. CONCLUSION: CysLT receptors are modulated immunologically, and montelukast inhibits up-regulation of CysLT(1) receptor and airway eosinophilic inflammation in asthmatic mice.