title: Absence of Fungal Spore Internalization by Bronchial Epithelium in Mouse Models Evidenced by a New Bioimaging Approach and Transmission Electronic Microscopy.
abstract: Clinical data and experimental studies suggest that bronchial epithelium could serve as a portal of entry for invasive fungal infections. We therefore analyzed the interactions between molds and the bronchial/bronchiolar epithelium at the early steps after inhalation. We developed invasive aspergillosis (Aspergillus fumigatus) and mucormycosis (Lichtheimia corymbifera) murine models that mimic the main clinical risk factors for these infections. Histopathology studies were completed with a specific computer-assisted morphometric method to quantify bronchial and alveolar spores and with transmission electron microscopy. Morphometric analysis revealed a higher number of bronchial/bronchiolar spores for A. fumigatus than L. corymbifera. The bronchial/bronchiolar spores decreased between 1 and 18 hours after inoculation for both fungi, except in corticosteroid-treated mice infected with A. fumigatus, suggesting an effect of cortisone on bronchial spore clearance. No increase in the number of spores of any species was observed over time at the basal pole of the epithelium, suggesting the lack of transepithelial crossing. Transmission electron microscopy did not show spore internalization by bronchial epithelial cells. Instead, spores were phagocytized by mononuclear cells on the apical pole of epithelial cells. Early epithelial internalization of fungal spores in vivo cannot explain the bronchial/bronchiolar epithelium invasion observed in some invasive mold infections. The bioimaging approach provides a useful means to accurately enumerate and localize the fungal spores in the pulmonary tissues.
authors.affiliation: Unit of Molecular Mycology, Institut Pasteur, Paris, France; URA 3012, The French National Centre for Scientific Research (CNRS), Paris, France; Infectious and Tropical Diseases Service, Hôpital Necker-Enfants Malades, APHP, Paris, France; Paris Diderot University, Bio Sorbonne Paris Cité, Paris, France. Electronic address: blandine.rammaert@pasteur.fr.
authors.forename: Blandine
authors.initials: B
authors.lastname: Rammaert
authors.affiliation: Unit of Human and Animal Model Histopathology, Institut Pasteur, Paris, France; Paris Descartes University, PRES Sorbonne-Paris-Cité, Paris, France.
authors.forename: Grégory
authors.initials: G
authors.lastname: Jouvion
authors.affiliation: Unit of Biological Image Analysis, Institut Pasteur, Paris, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: de Chaumont
authors.affiliation: Unit of Molecular Mycology, Institut Pasteur, Paris, France; URA 3012, The French National Centre for Scientific Research (CNRS), Paris, France.
authors.forename: Dea
authors.initials: D
authors.lastname: Garcia-Hermoso
authors.affiliation: Cellular Health Imaging Center, Université d'Auvergne, Clermont Ferrand, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Szczepaniak
authors.affiliation: Unit of Molecular Mycology, Institut Pasteur, Paris, France; URA 3012, The French National Centre for Scientific Research (CNRS), Paris, France.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Renaudat
authors.affiliation: Unit of Biological Image Analysis, Institut Pasteur, Paris, France.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Olivo-Marin
authors.affiliation: Unit of Human and Animal Model Histopathology, Institut Pasteur, Paris, France; Paris Descartes University, PRES Sorbonne-Paris-Cité, Paris, France; Neuropathology Service, Centre Hospitalier Sainte-Anne, Assistance Publique-Hôpitaux de Paris, Paris, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Chrétien
authors.affiliation: URA 3012, The French National Centre for Scientific Research (CNRS), Paris, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Dromer
authors.affiliation: Unit of Molecular Mycology, Institut Pasteur, Paris, France; Paris Diderot University, Bio Sorbonne Paris Cité, Paris, France; Parasitology-Mycology Service, Hôpital St Louis, AP-HP, Paris, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Bretagne
mesh_terms: D000818:Animals; D001228:Aspergillosis / Q000378:metabolism / Q000382:microbiology* / Q000473:pathology; D001232:Aspergillus fumigatus; D002463:Cell Membrane Permeability; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000276:immunology / Q000648:ultrastructure*; D004848:Epithelium / Q000473:pathology*; D006801:Humans; D008168:Lung / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D008297:Male; D051379:Mice; D046529:Microscopy, Electron, Transmission; D010587:Phagocytosis / Q000276:immunology; D013172:Spores, Fungal / Q000378:metabolism*