Penetration of the Human Pulmonary Epithelium by Aspergillus fumigatus Hyphae.

Background: The airway epithelium is the first barrier interacting with Aspergillus fumigatus conidia after their inhalation, suggesting that this structure functions as point of entry of this fungus to initiate pulmonary aspergillosis.

Methods: To study epithelial entry by A fumigatus, primary human reconstituted pseudostratified epithelium cultured in air-liquid interface as well as bronchial epithelial cell monolayers were infected with conidia.

Results: Under these experimental conditions, we found that A fumigatus hyphae traversed the bronchial epithelium through a mechanism involving the recruitment of actin, which formed a tunnel that allows hyphae to enter the cells without disturbing their integrity.

Conclusions: These findings describe a new mechanism by which A fumigatus hyphae penetrate the airway epithelial barrier and can infect its human host.