The immune mechanisms that recognize inhaled Aspergillus fumigatus conidia to promote their elimination from the lungs are incompletely understood. FleA is a lectin expressed by Aspergillus fumigatus that has twelve binding sites for fucosylated structures that are abundant in the glycan coats of multiple plant and animal proteins. The role of FleA is unknown: it could bind fucose in decomposed plant matter to allow Aspergillus fumigatus to thrive in soil, or it may be a virulence factor that binds fucose in lung glycoproteins to cause Aspergillus fumigatus pneumonia. Our studies show that FleA protein and Aspergillus fumigatus conidia bind avidly to purified lung mucin glycoproteins in a fucose-dependent manner. In addition, FleA binds strongly to macrophage cell surface proteins, and macrophages bind and phagocytose fleA-deficient (∆fleA) conidia much less efficiently than wild type (WT) conidia. Furthermore, a potent fucopyranoside glycomimetic inhibitor of FleA inhibits binding and phagocytosis of WT conidia by macrophages, confirming the specific role of fucose binding in macrophage recognition of WT conidia. Finally, mice infected with ΔfleA conidia had more severe pneumonia and invasive aspergillosis than mice infected with WT conidia. These findings demonstrate that FleA is not a virulence factor for Aspergillus fumigatus. Instead, host recognition of FleA is a critical step in mechanisms of mucin binding, mucociliary clearance, and macrophage killing that prevent Aspergillus fumigatus pneumonia.

Center for Synthesis and Chemical Biology University College Dublin Dublin Ireland

Department of Genetics University of Wisconsin Madison Madison Wisconsin

Department of Laboratory Medicine University of California San Francisco San Francisco California

Department of Medical Microbiology and Immunology University of Wisconsin Madison Madison Wisconsin

Division of Pulmonary and Critical Care Medicine University of California San Francisco San Francisco California

Faculty of Science and Central European Institute of Technology Masaryk University Brno Czech Republic

Veterinary Science Centre School of Agriculture Food Science and Veterinary Medicine University College Dublin Dublin Ireland

See more in PubMed

Dagenais TR, Keller NP. Pathogenesis of PubMed DOI PMC

Bhatia S, Fei M, Yarlagadda M, Qi Z, Akira S, Saijo S, et al. Rapid host defense against PubMed DOI PMC

Dubourdeau M, Athman R, Balloy V, Huerre M, Chignard M, Philpott DJ, et al. PubMed

Philippe B, Ibrahim-Granet O, Prevost MC, Gougerot-Pocidalo MA, Sanchez Perez M, Van der Meeren A, et al. Killing of PubMed PMC

Saijo S, Iwakura Y. Dectin-1 and Dectin-2 in innate immunity against fungi. International Immunology. 2011;23(8):467–72. 10.1093/intimm/dxr046 PubMed DOI

Luther K, Torosantucci A, Brakhage AA, Heesemann J, Ebel F. Phagocytosis of PubMed

Underhill DM. Toll-like receptors and microbes take aim at each other. Curr Opin Immunol. 2004;16(4):483–7. PubMed

Willment JA, Brown GD. C-type lectin receptors in antifungal immunity. Trends in Microbiology. 2008;16(1):27–32. PubMed

Slesiona S, Gressler M, Mihlan M, Zaehle C, Schaller M, Barz D, et al. Persistence versus escape: PubMed DOI PMC

Gilboa-Garber N. PubMed

Kostlanova N, Mitchell EP, Lortat-Jacob H, Oscarson S, Lahmann M, Gilboa-Garber N, et al. The fucose-binding lectin from PubMed

Ramphal R, Arora SK. Recognition of mucin components by PubMed

Sulak O, Cioci G, Delia M, Lahmann M, Varrot A, Imberty A, et al. A TNF-like trimeric lectin domain from PubMed DOI

Zinger-Yosovich K, Sudakevitz D, Imberty A, Garber NC, Gilboa-Garber N. Production and properties of the native PubMed

Fukumori F, Takeuchi N, Hagiwara T, Ohbayashi H, Endo T, Kochibe N, et al. Primary structure of a fucose-specific lectin obtained from a mushroom, PubMed

Ishida H, Moritani T, Hata Y, Kawato A, Suginami K, Abe Y, et al. Molecular cloning and overexpression of fleA gene encoding a fucose-specific lectin of PubMed

Matsumura K, Higashida K, Hata Y, Kominami J, Nakamura-Tsuruta S, Hirabayashi J. Comparative analysis of oligosaccharide specificities of fucose-specific lectins from PubMed DOI

Houser J, Komarek J, Kostlanova N, Cioci G, Varrot A, Kerr SC, et al. A soluble fucose-specific lectin from PubMed DOI PMC

Wimmerova M, Mitchell E, Sanchez JF, Gautier C, Imberty A. Crystal structure of fungal lectin: six-bladed β-propeller fold and novel fucose recognition mode for PubMed

Houser J, Komarek J, Cioci G, Varrot A, Imberty A, Wimmerova M. Structural insights into PubMed DOI

Audfray A, Claudinon J, Abounit S, Ruvoen-Clouet N, Larson G, Smith DF, et al. Fucose-binding lectin from opportunistic pathogen PubMed DOI PMC

Rose MC. Mucins: structure, function, and role in pulmonary diseases. Am J Physiol. 1992;263(4 Pt 1):L413–29. PubMed

Thornton DJ, Rousseau K, McGuckin MA. Structure and function of the polymeric mucins in airways mucus. Annu Rev Physiol. 2008;70:459–86. PubMed

Xu X, Padilla MT, Li B, Wells A, Kato K, Tellez C, et al. MUC1 in macrophage: contributions to cigarette smoke-induced lung cancer. Cancer Research. 2014;74(2):460–70. 10.1158/0008-5472.CAN-13-1713 PubMed DOI PMC

Roy MG, Livraghi-Butrico A, Fletcher AA, McElwee MM, Evans SE, Boerner RM, et al. Muc5b is required for airway defence. Nature. 2014;505(7483):412–6. 10.1038/nature12807 PubMed DOI PMC

Kim KC. Role of epithelial mucins during airway infection. Pulmonary Pharmacology & Therapeutics. 2012;25(6):415–9. PubMed PMC

Petersen TN, Brunak S, von Heijne G, Nielsen H. SignalP 4.0: discriminating signal peptides from transmembrane regions. Nature Methods. 2011;8(10):785–6. 10.1038/nmeth.1701 PubMed DOI

Bouckaert J, Berglund J, Schembri M, De Genst E, Cools L, Wuhrer M, et al. Receptor binding studies disclose a novel class of high-affinity inhibitors of the PubMed

Bouchara JP, Sanchez M, Chevailler A, Marot-Leblond A, Lissitzky JC, Tronchin G, et al. Sialic acid-dependent recognition of laminin and fibrinogen by PubMed PMC

Bromley IM, Donaldson K. Binding of PubMed PMC

Tronchin G, Bouchara JP, Larcher G, Lissitzky JC, Chabasse D. Interaction between PubMed

Wasylnka JA, Moore MM. Adhesion of PubMed PMC

Bonnett CR, Cornish EJ, Harmsen AG, Burritt JB. Early neutrophil recruitment and aggregation in the murine lung inhibit germination of PubMed PMC

Cunha C, Kurzai O, Loffler J, Aversa F, Romani L, Carvalho A. Neutrophil responses to aspergillosis: new roles for old players. Mycopathologia. 2014;178(5–6):387–93. 10.1007/s11046-014-9796-7 PubMed DOI

Taylor PR, Tsoni SV, Willment JA, Dennehy KM, Rosas M, Findon H, et al. Dectin-1 is required for β-glucan recognition and control of fungal infection. Nat Immunol. 2007;8(1):31–8. PubMed PMC

Hohl TM, Van Epps HL, Rivera A, Morgan LA, Chen PL, Feldmesser M, et al. PubMed PMC

Carrion Sde J, Leal SM Jr., Ghannoum MA, Aimanianda V, Latge JP, Pearlman E. The RodA hydrophobin on PubMed DOI PMC

Gersuk GM, Underhill DM, Zhu L, Marr KA. Dectin-1 and TLRs permit macrophages to distinguish between different PubMed

Peters MC, Mekonnen ZK, Yuan S, Bhakta NR, Woodruff PG, Fahy JV. Measures of gene expression in sputum cells can identify TH2-high and TH2-low subtypes of asthma. J Allergy Clin Immunol. 2014;133(2):388–94. 10.1016/j.jaci.2013.07.036 PubMed DOI PMC

Kerr SC, Carrington SD, Oscarson S, Gallagher ME, Solon M, Yuan S, et al. Intelectin-1 is a prominent protein constituent of pathologic mucus associated with eosinophilic airway inflammation in asthma. Am J Respir Crit Care Med. 2014;189(8):1005–7. 10.1164/rccm.201312-2220LE PubMed DOI PMC

Royle L, Matthews E, Corfield A, Berry M, Rudd PM, Dwek RA, et al. Glycan structures of ocular surface mucins in man, rabbit and dog display species differences. Glycoconj J. 2008;25(8):763–73. 10.1007/s10719-008-9136-6 PubMed DOI

Lemieux RU, Hendriks KB, Stick RV, James K. Halide ion catalyzed glycosidation reactions. Synthesis of α-linked disaccharides. Journal of the American Chemical Society. 1975;97:4056–62.

Shimizu K, Keller NP. Genetic involvement of a cAMP-dependent protein kinase in a G protein signaling pathway regulating morphological and chemical transitions in PubMed PMC

Chang PK, Scharfenstein LL, Wei Q, Bhatnagar D. Development and refinement of a high-efficiency gene-targeting system for PubMed DOI