期刊
INFECTION AND IMMUNITY
卷 77, 期 7, 页码 2783-2794出版社
AMER SOC MICROBIOLOGY
DOI: 10.1128/IAI.00088-09
关键词
-
资金
- NIH [HL-30923, HL-51134, AI73896, AI28388, AI42159, AI50184]
- ANR
Cryptococcus neoformans is a facultative intracellular opportunistic pathogen and the leading cause of fungal meningitis in humans. In the absence of a protective cellular immune response, the inhalation of C. neoformans cells or spores results in pulmonary infection. C. neoformans cells produce a polysaccharide capsule composed predominantly of glucuronoxylomannan, which constitutes approximately 90% of the capsular material. In the lungs, surfactant protein A (SP-A) and SP-D contribute to immune defense by facilitating the aggregation, uptake, and killing of many microorganisms by phagocytic cells. We hypothesized that SP-D plays a role in C. neoformans pathogenesis by binding to and enhancing the phagocytosis of the yeast. Here, the abilities of SP-D to bind to and facilitate the phagocytosis and survival of the wild-type encapsulated strain H99 and the cap59 Delta mutant hypocapsular strain are assessed. SP-D binding to cap59 Delta mutant cells was approximately sixfold greater than binding to wild-type cells. SP-D enhanced the phagocytosis of cap59 Delta cells by approximately fourfold in vitro. To investigate SP-D binding in vivo, SP-D-/- mice were intranasally inoculated with Alexa Fluor 488-labeled cap59 Delta or H99 cells. By confocal microscopy, a greater number of phagocytosed C. neoformans cells in wild-type mice than in SP-D-/- mice was observed, consistent with in vitro data. Interestingly, SP-D protected C. neoformans cells against macrophage-mediated defense mechanisms in vitro, as demonstrated by an analysis of fungal viability using a CFU assay. These findings provide evidence that C. neoformans subverts host defense mechanisms involving surfactant, establishing a novel virulence paradigm that may be targeted for therapy.
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