Aspergillus fumigatus germ tube growth and not conidia ingestion induces expression of inflammatory mediator genes in the human lung epithelial cell line A549.
Inhalation of conidia is the main cause of invasive pulmonary aspergillosis (IPA) and the respiratory epithelium is the first line of defence. To explore the triggering factor for the inflammatory response to Aspergillus fumigatus, the species mainly responsible for IPA, this study analysed the differential expression of three inflammatory genes in A549 cells after challenge with live and killed conidia. The influence of steroids, one of the main risk factors for developing IPA, was also investigated. Quantification of mRNAs of the inflammatory mediator genes encoding interleukin (IL)-8, tumour necrosis factor (TNF)-alpha and granulocyte-monocyte colony-stimulating factor (GM-CSF) was carried out using real-time PCR. Ingestion rates were studied for the conidia of A. fumigatus and Penicillium chrysogenum using a fluorescence brightener. Similar results were obtained for both species, with ingestion rates ranging from 35 to 40 %. Exposure of A549 cells to live A. fumigatus conidia only induced a four- to fivefold increase in the mRNA levels of the three genes, starting 8 h after the initial contact. Both inactivation of live A. fumigatus conidia and treatment by dexamethasone (10(-7) M) prevented the overexpression of TNF-alpha, IL-8 and GM-CSF. Fungal growth, rather than conidia ingestion, appears to be the main stimulus for the production of inflammatory mediators by epithelial cells, and this production is inhibited by steroid therapy. These results underline the role that the epithelium plays in the innate response against IPA.
Bellanger
Anne-Pauline
AP
UMR 6249 CNRS, Laboratoire de Parasitologie-Mycologie, Hôpital Jean Minjoz, Besançon, France.
Millon
Laurence
L
UMR 6249 CNRS, Laboratoire de Parasitologie-Mycologie, Hôpital Jean Minjoz, Besançon, France.
Khoufache
Khaled
K
UMR BIPAR 956, Laboratoire de Parasitologie-Mycologie, Hôpital Henri Mondor and Université Paris-Est, Créteil, France.
Rivollet
Danièle
D
UMR BIPAR 956, Laboratoire de Parasitologie-Mycologie, Hôpital Henri Mondor and Université Paris-Est, Créteil, France.
Bièche
Ivan
I
UMR INSERM 745, Université Paris Descartes, Faculté des Sciences Pharmaceutiques et Biologique, Paris, France.
Laurendeau
Ingrid
I
UMR INSERM 745, Université Paris Descartes, Faculté des Sciences Pharmaceutiques et Biologique, Paris, France.
Vidaud
Michel
M
UMR INSERM 745, Université Paris Descartes, Faculté des Sciences Pharmaceutiques et Biologique, Paris, France.
Botterel
Françoise
F
UMR BIPAR 956, Laboratoire de Parasitologie-Mycologie, Hôpital Henri Mondor and Université Paris-Est, Créteil, France.
Bretagne
Stéphane
S
UMR BIPAR 956, Laboratoire de Parasitologie-Mycologie, Hôpital Henri Mondor and Université Paris-Est, Créteil, France.
D001232:Aspergillus fumigatus / Q000276:immunology*; D002460:Cell Line; D016207:Cytokines / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D004847:Epithelial Cells / Q000276:immunology* / Q000382:microbiology*; D020869:Gene Expression Profiling; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D010408:Penicillium chrysogenum / Q000276:immunology; D016133:Polymerase Chain Reaction / Q000379:methods; D020545:Respiratory Mucosa / Q000276:immunology* / Q000382:microbiology*; D013172:Spores, Fungal / Q000276:immunology; D013256:Steroids / Q000494:pharmacology
D016207:Cytokines; D007166:Immunosuppressive Agents; D013256:Steroids