Bromelain exerts anti-inflammatory effects in an ovalbumin-induced murine model of allergic airway disease

Objective: Bromelain, a clinically used pineapple extract and natural product, has reported anti-inflammatory and immunomodulatory activities. The purpose of this study was to determine the effect of bromelain treatment in an ovalbumin (OVA)-induced murine model of allergic airway disease (AAD). Methods: To establish AAD, mice were sensitized with intraperitoneal (i.p.) OVA/alum and challenged with daily OVA aerosols. Mice were treated i.p. with either saline, 2 or 6 mg/kg bromelain, twice daily for four consecutive days. Bronchoalveolar lavage leukocytes and cytokines, lung histology, airway hyperresponsiveness, and lymphocyte populations via flow cytometry were compared between groups. Results: Bromelain treatment of AAD mice resulted in reduced total BAL leukocytes, eosinophils, CD4(+) and CD8(+) T lymphocytes, CD4(+)/CD8(+) T cell ratio, and IL-13. Conclusion: Bromelain attenuated development of AAD while altering CD4(+) to CD8(+) T lymphocyte populations. The reduction in AAD outcomes suggests that bromelain may have similar effects in the treatment of human asthma and hypersensitivity disorders. (c) 2005 Elsevier Inc. All rights reserved.