Published ahead of print on March 3, 2005, doi:10.1165/rcmb.2005-0059OC
© 2005 American Thoracic Society DOI: 10.1165/rcmb.2005-0059OC Lysozyme Secretion by Submucosal Glands Protects the Airway from Bacterial InfectionDepartment of Anatomy and Cell Biology, Department of Internal Medicine, Department of Microbiology, Center for Gene Therapy, and Howard Hughes Medical Institute, University of Iowa, Iowa City, Iowa Correspondence and requests for reprints should be addressed to John F. Engelhardt, Department of Anatomy and Cell Biology, University of Iowa, Room 1-111 Bowen Science Building, 51 Newton Road, Iowa City, IA 52242-1109. E-mail: john-engelhardt{at}uiowa.edu
Submucosal glands are abundant (
Key Words: innate immunity • lung • lysozyme • glands • antibacterial proteins This article has been cited by other articles:
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1 gland/mm2) secretory structures in the tracheobronchial airways of the human lung. Because submucosal glands express antibacterial proteins, it has been proposed that they contribute to lung defense. However, this concept is challenged by the fact that mice do not have submucosal glands in their bronchial airways, yet are quite resistant to bacterial lung infection. The contribution of airway submucosal glands to host defense is also debated as a pathophysiologic component of cystic fibrosis lung disease. Here, we asked whether submucosal glands protect airways against bacterial infection. By comparing tracheal xenograft airways with and without glands, we found that the presence of glands enhanced bacterial killing in vivo and by airway secretions in vitro. Moreover, immunodepletion studies suggested that lysozyme is a major antibacterial component secreted by submucosal glands. These studies provide evidence that submucosal glands are a major source of antibacterials critical for maintaining sterile airways. 
