title: Germination of Aspergillus fumigatus inside avian respiratory macrophages is associated with cytotoxicity.
abstract: Although aspergillosis is one of the most common diseases in captive birds, the pathogenesis of avian aspergillosis is poorly known. We studied the role of avian respiratory macrophages as a first line of defense against avian aspergillosis. The phagocytic and killing capacities of avian respiratory macrophages were evaluated using pigeon respiratory macrophages that were inoculated with Aspergillus fumigatus conidia. On average, 25% of macrophage-associated conidia were phagocytosed after one hour. Sixteen percents of these cell-associated conidia were killed after 4 h and conidial germination was inhibited in more than 95% of the conidia. A. fumigatus conidia were shown to be cytotoxic to the macrophages. Intracellularly germinating conidia were located free in the cytoplasm of necrotic cells, as shown using transmission electron microscopy. These results suggest that avian respiratory macrophages may prevent early establishment of infection, unless the number of A. fumigatus conidia exceeds the macrophage killing capacity, leading to intracellular germination and colonization of the respiratory tract.
authors.affiliation: The Department of Pathology, Bacteriology and Avian diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820, Merelbeke, Belgium. Lieven.vanwaeyenberghe@ugent.be.
authors.forename: Lieven
authors.initials: L
authors.lastname: Van Waeyenberghe
authors.forename: Frank
authors.initials: F
authors.lastname: Pasmans
authors.forename: Katharina
authors.initials: K
authors.lastname: D'Herde
authors.forename: Richard
authors.initials: R
authors.lastname: Ducatelle
authors.forename: Herman
authors.initials: H
authors.lastname: Favoreel
authors.forename: Shao-Ji
authors.initials: SJ
authors.lastname: Li
authors.forename: Freddy
authors.initials: F
authors.lastname: Haesebrouck
authors.forename: An
authors.initials: A
authors.lastname: Martel
mesh_terms: D000818:Animals; D001228:Aspergillosis / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D001232:Aspergillus fumigatus / Q000254:growth & development* / Q000276:immunology; D001715:Bird Diseases / Q000276:immunology* / Q000382:microbiology; D010856:Columbidae; D003602:Cytotoxicity, Immunologic; D016676:Macrophages, Alveolar / Q000276:immunology* / Q000382:microbiology; D046529:Microscopy, Electron, Transmission / Q000662:veterinary; D008856:Microscopy, Fluorescence / Q000662:veterinary; D012137:Respiratory System; D013172:Spores, Fungal / Q000254:growth & development / Q000276:immunology