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: Günter Rambach, Gerhard Blum, Jean-Paul Latgé, Thierry Fontaine, Thorsten Heinekamp, Magdalena Hagleitner, Hanna Jeckström, Günter Weigel, Philipp Würtinger, Kristian Pfaller, Sven Krappmann, Jürgen Löffler, Cornelia Lass-Flörl, Cornelia Speth
• Journal: The Journal of infectious diseases (J Infect Dis) Vol. 212 Issue 7 Pg. 1140-9 (Oct 01 2015) ISSN: 1537-6613 [Electronic] United States
• PMID: 25810442 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: [email protected].

Chemical References

• Antigens, Surface
• Fungal Proteins
• Melanins
• Polysaccharides
• Virulence Factors
• beta-Glucans
• galactosaminogalactan
• Chitin

Topics

• Antigens, Surface (immunology)
• Aspergillosis (microbiology)
• Aspergillus fumigatus (chemistry, physiology)
• Blood Platelets (microbiology, ultrastructure)
• Chitin (immunology)
• Flow Cytometry
• Fungal Proteins (immunology)
• Humans
• Hyphae (chemistry, physiology)
• Immunity, Innate (immunology)
• Melanins (immunology)
• Platelet Activation
• Polysaccharides (immunology)
• Spores, Fungal (chemistry, physiology)
• Virulence Factors (immunology)
• beta-Glucans (immunology)