title: Identification of Aspergillus fumigatus Surface Components That Mediate Interaction of Conidia and Hyphae With Human Platelets.
abstract: BACKGROUND
  Platelets were recently identified as a part of innate immunity. They are activated by contact with Aspergillus fumigatus; putative consequences include antifungal defense but also thrombosis, excessive inflammation, and thrombocytopenia. We aimed to identify those fungal surface structures that mediate interaction with platelets.
  
  
  METHODS
  Human platelets were incubated with Aspergillus conidia and hyphae, isolated wall components, or fungal surface mutants. Interaction was visualized microscopically; activation was quantified by flow cytometry of specific markers.
  
  
  RESULTS
  The capacity of A. fumigatus conidia to activate platelets is at least partly due to melanin, because this effect can be mimicked with "melanin ghosts"; a mutant lacking melanin showed reduced platelet stimulating potency. In contrast, conidial hydrophobin masks relevant structures, because an A. fumigatus mutant lacking the hydrophobin protein induced stronger platelet activation than wild-type conidia. A. fumigatus hyphae also contain surface structures that interact with platelets. Wall proteins, galactomannan, chitin, and β-glucan are not the relevant hyphal components; instead, the recently identified fungal polysaccharide galactosaminogalactan potently triggered platelet activation.
  
  
  CONCLUSIONS
  Conidial melanin and hydrophobin as well as hyphal galactosaminogalactan represent important pathogenicity factors that modulate platelet activity and thus might influence immune responses, inflammation, and thrombosis in infected patients.
authors: Division of Hygiene and Medical Microbiology.
authors: Günter
authors: G
authors: Rambach
authors: Division of Hygiene and Medical Microbiology.
authors: Gerhard
authors: G
authors: Blum
authors: Unité des Aspergillus and Unité de Chimie et Biocatalyse, Institut Pasteur, Paris, France.
authors: Jean-Paul
authors: JP
authors: Latgé
authors: Unité des Aspergillus and Unité de Chimie et Biocatalyse, Institut Pasteur, Paris, France.
authors: Thierry
authors: T
authors: Fontaine
authors: Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology-Hans Knöll Institute, Jena.
authors: Thorsten
authors: T
authors: Heinekamp
authors: Division of Hygiene and Medical Microbiology.
authors: Magdalena
authors: M
authors: Hagleitner
authors: Division of Hygiene and Medical Microbiology.
authors: Hanna
authors: H
authors: Jeckström
authors: Institute of Medical and Chemical Laboratory Diagnostics, University Hospital Innsbruck, Austria.
authors: Günter
authors: G
authors: Weigel
authors: Institute of Medical and Chemical Laboratory Diagnostics, University Hospital Innsbruck, Austria.
authors: Philipp
authors: P
authors: Würtinger
authors: Division of Histology and Embryology, Medical University of Innsbruck.
authors: Kristian
authors: K
authors: Pfaller
authors: Friedrich-Alexander-University Erlangen-Nürnberg.
authors: Sven
authors: S
authors: Krappmann
authors: Medical Hospital II, University Hospital Würzburg, Germany.
authors: Jürgen
authors: J
authors: Löffler
authors: Division of Hygiene and Medical Microbiology.
authors: Cornelia
authors: C
authors: Lass-Flörl
authors: Division of Hygiene and Medical Microbiology.
authors: Cornelia
authors: C
authors: Speth
mesh_terms: D000954:Antigens, Surface / Q000276:immunology*; D001228:Aspergillosis / Q000382:microbiology*; D001232:Aspergillus fumigatus / Q000737:chemistry / Q000502:physiology*; D001792:Blood Platelets / Q000382:microbiology* / Q000648:ultrastructure; D002686:Chitin / Q000276:immunology; D005434:Flow Cytometry; D005656:Fungal Proteins / Q000276:immunology*; D006801:Humans; D025301:Hyphae / Q000737:chemistry / Q000502:physiology; D007113:Immunity, Innate / Q000276:immunology; D008543:Melanins / Q000276:immunology*; D015539:Platelet Activation; D011134:Polysaccharides / Q000276:immunology; D013172:Spores, Fungal / Q000737:chemistry / Q000502:physiology; D037521:Virulence Factors / Q000276:immunology; D047071:beta-Glucans / Q000276:immunology
chemical_list: D000954:Antigens, Surface; D005656:Fungal Proteins; D008543:Melanins; D011134:Polysaccharides; D037521:Virulence Factors; D047071:beta-Glucans; C062157:galactosaminogalactan; D002686:Chitin
keywords: Aspergillus fumigatus; fungal surface; galactosaminogalactan; hydrophobin; innate immunity; invasive aspergillosis; melanin; platelets