In vivo airway eosinophil accumulation induced by polymyxin-B reduces bronchial responsiveness in guinea pigs
Article first published online: 12 JAN 2002
Clinical & Experimental Allergy
Volume 31, Issue 4, pages 644–651, April 2001
How to Cite
Ishiura, Y., Fujimura, M., Myou, S., Nobata, K., Liu, Q., Yamamori, C. and Amemiya, T. (2001), In vivo airway eosinophil accumulation induced by polymyxin-B reduces bronchial responsiveness in guinea pigs. Clinical & Experimental Allergy, 31: 644–651. doi: 10.1046/j.1365-2222.2001.01107.x
- Issue published online: 12 JAN 2002
- Article first published online: 12 JAN 2002
- Submitted 27 April 2000; revised 14 July 2000; accepted 20 November 2000.
- airway eosinophil accumulation;
- bronchial responsiveness
Background Chronic desquamative eosinophilic bronchitis and bronchial hyperresponsiveness have been considered essential for bronchial asthma. However, it has not been studied whether airway eosinophils enhance or inhibit bronchial responsiveness in vivo.
Objective This study was conducted to elucidate the influence of airway eosinophil accumulation on bronchial responsiveness in vivo.
Materials and methods Guinea pigs were transnasally treated with 75 µg/kg of polymyxin-B or vehicle twice a week for a total of 3 weeks. Guinea pigs were surgically cannulated and artificially ventilated 24 h after the last administration of polymyxin-B or vehicle. Ten minutes after the installation of artificial ventilation, ascending doses of methacholine, acetylcholine or histamine were inhaled for 20 s at intervals of 5 min. Subsequent study was conducted 20 min after treatment of 60 mg/kg of indomethacin in the same manner. Final study was conducted in naive guinea pigs after single inhalation of 75 µg/mL of polymyxin B.
Results The proportion of eosinophils in bronchoalveolar lavage fluid significantly increased in guinea pigs treated with polymyxin-B compared with vehicle. Bronchial responsiveness to inhaled methacholine, acetylcholine and histamine was significantly decreased by the polymyxin-B treatment. This protective effect induced by polymyxin B was abolished by pretreatment of indomethacin. A significant increase in bronchial responsiveness was observed after a single inhalation of polymyxin B.
Conclusion These results suggest that in vivo airway eosinophils may reduce non-specific bronchial responsiveness through inhibitory or bronchoprotective prostanoids.