Structural characterization of the new immunosuppressive galactosaminogalactan produced by Aspergillus fumigatus

Ref ID: 19603

Author:

T Fontaine1*, L Muszkieta1, A Delangle1, C Simenel2, S Bozza3, S Moretti3, M Delepierre2,
C Elbim4, MS Gresnigt5, FL van de Veerdonk5, L Romani3, JP Latgé1

Author address:

1Unité des Aspergillus, Institut Pasteur, Paris France
2Unité de Résonance Magnétique Nucléaire des Biomolécules, Institut Pasteur, Paris
3Department of experimental medicine and biochemical sciences, University of Perugia, Perugia, Italy
4Univers

Full conference title:

6th Advances Against Aspergillosis 2014

Abstract:

Purpose:
The galactosaminogalactan (GAG) is a new antigenic polysaccharide secreted by the human
opportunistic fungal pathogen Aspergillus fumigatus during infection particularly during invasive
aspergillosis. GAG is also an adhesin involved in the biofilm formation on abiotic support. Structure
and function have been investigated.
Methods:
Immunological studies of GAG were carried on humans cells and murine model. Structural
characterization was performed by carbohydrate analysis using specific chemical degradations,
mass spectrometry and NMR.
Results:
In murine model, GAG promotes fungal development in immunocompetent mice due to its
immunosuppressive activity that is associated to a decrease of neutrophil infiltrates in lung.
Particularly, GAG induced neutrophil apoptosis. Carbohydrate analysis showed that this polysaccharide
is a linear heterogeneous galactosaminogalactan composed of α 1-4 linked galactose and
α 1-4 linked N-acetylgalactosamine residues where both monosacharides are randomly distributed
and with variable percentage of galactose per chain. The apparent Mr was estimated by gel filtration
chromatography, this polysaccharide was eluted as a polydisperse homogenous polymer between 10
and 1000 kDa with an average of 100 kDa. A specific glycosyltransferase has been identified. The
deletion mutant does not produce GAG anymore and its phenotype is currently analysed.
Conclusion:
GAG is the first fungal described immunosuppressive polysaccharide that favours the fungal
infection.

Abstract Number: 128

Conference Year: 2014

Link to conference website: http://www.AAA2014.org

New link: NULL

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