Protocol for sensitization and challenge was based on the previous published method with minor modification (23 (link)). Briefly, mice were injected intraperitoneally (i.p.) on days 0, 3, 5 with HDM extract containing 10 µg of Der p1 (Indoor Biotechnologies, VA, USA) in 200 µL of sterile saline and then challenged intranasally (i.n.) with the same agent on days 10, 12 14, 16, and 17. Control mice were received phosphate-buffered saline (PBS) during the sensitization and challenge phases. Mice were sacrificed 24 hours after the last challenge for airway reactivity measurement.