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Sublingual Immunotherapy as an Alternative to Induce Protection Against Acute Respiratory Infections
Published on: August 30, 2014
Lysozyme secretion by submucosal glands protects the airway from bacterial infection
Rana Dajani1, Yulong Zhang, Peter J Taft
1Department of Anatomy and Cell Biology, Center for Gene Therapy, Howard Hughes Medical Institute, University of Iowa, 51 Newton Road, Iowa City, IA 52242-1109, USA.
Abstract:
Submucosal glands are abundant (approximately 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.
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