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Fungal melanin stimulates surfactant protein D-mediated opsonization of and host immune response to Aspergillus fumigatus spores
S.S. Wah Wong, M. Rani, E. Dodagatta-Marri, O. Ibrahim-Granet, U. Kishore, , J.-P. Latgé, A. Sahu, T. Madan, V. Aimanianda
Published in American Society for Biochemistry and Molecular Biology Inc.
2018
PMID: 29414772
Volume: 293
   
Issue: 13
Pages: 4901 - 4912
Abstract
Surfactant protein D (SP-D), a C-type lectin and pattern-recognition soluble factor, plays an important role in immune surveillance to detect and eliminate human pulmonary pathogens. SP-D has been shown to protect against infections with the most ubiquitous airborne fungal pathogen, Aspergillus fumigatus, but the fungal surface component(s) interacting with SP-D is unknown. Here, we show that SP-D binds to melanin pigment on the surface of A. fumigatus dormant spores (conidia). SP-D also exhibited an affinity to two cell-wall polysaccharides of A. fumigatus, galactomannan (GM) and galactosaminogalactan (GAG). The immunolabeling pattern of SP-D was punctate on the conidial surface and was uniform on germinating conidia, in accordance with the localization of melanin, GM, and GAG. We also found that the collagen-like domain of SP-D is involved in its interaction with melanin, whereas its carbohydrate-recognition domain recognized GM and GAG. Unlike un-opsonized conidia, SP-D- opsonized conidia were phagocytosed more efficiently and stimulated the secretion of proinflammatory cytokines by human monocyte-derived macrophages. Furthermore, SP-D/ mice challenged intranasally with wildtype conidia or melanin ghosts (i.e. hollow melanin spheres) displayed significantly reduced proinflammatory cytokines in the lung compared with wildtype mice. In summary, SP-D binds to melanin present on the dormant A. fumigatus conidial surface, facilitates conidial phagocytosis, and stimulates the host immune response. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.
About the journal
JournalJournal of Biological Chemistry
PublisherAmerican Society for Biochemistry and Molecular Biology Inc.
ISSN00219258
Open AccessNo