INTRAVASCULAR CLEARANCE OF DISSEMINATING CRYPTOCOCCUS NEOFORMANS

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dc.contributor.advisorShi, Meiqingen_US
dc.contributor.authorSun, Dongleien_US
dc.contributor.departmentVeterinary Medical Scienceen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2018-09-13T05:34:15Z
dc.date.available2018-09-13T05:34:15Z
dc.date.issued2018en_US
dc.description.abstractCryptococcus neoformans (C. neoformans) is an opportunistic fungal pathogen causing fatal cryptococcal meningoencephalitis in humans. The initial infection organ of C. neoformans is the lung; however, lung infection is commonly seen in healthy individuals and does not always have symptoms. Under certain conditions, the fungi may disseminate out of the lung and enter blood circulation. The fungi, once trapped in the brain vasculature, will breach the blood-brain barrier and proliferate rapidly leading to fatal outcomes. Considering the weak immune responses in the brain, it is important to limit the possibility for fungi to arrive at the brain. The current dissertation focused on the interactions of C. neoformans with host immune cells after pulmonary dissemination, seeking mechanisms that can clear the fungi from circulation. It is identified that neutrophils have the ability to remove fungi from the brain vasculature. This effective fungicidal cell kills C. neoformans via C5a-C5aR and CD11b axis. The C5aR signaling provides navigation and alerts neutrophils by up-regulating CD11b surface expression, CD11b as complement receptor is essential for subsequent uptake and killing of fungi by neutrophils. In vivo, neutrophil clearance of C. neoformans occurs in the brain vasculature but the effect is more efficient in the lung vasculature because lung is able to recruit massive amount of neutrophils into the vasculature through complement activation and C5aR signaling, which induce neutrophil actin polymerization and increase their retention. Neutrophils once activated by C. neoformans can further augment self-recruitment through the release of leukotriene B4. Directing neutrophils to the brain can help with fungal clearance in the brain. Moreover, using intravital microscopy, we reported that liver Kupffer cells can filter disseminating C. neoformans. This filtering requires C3b deposition on the fungal surface to provide the holding force and CRIg on the Kupffer cells. Without the holding force, fungi in the liver have higher tendency to be flushed back into circulation. The Kupffer cells rapidly phagocytize the captured fungi and suppress their proliferation in an IFN-γ independent way. Collectively, the results suggest that neutrophils and liver Kupffer cells are critically involved during intravascular clearance of C. neoformans.en_US
dc.identifierhttps://doi.org/10.13016/M2FT8DN9T
dc.identifier.urihttp://hdl.handle.net/1903/21330
dc.language.isoenen_US
dc.subject.pqcontrolledImmunologyen_US
dc.subject.pqcontrolledVeterinary scienceen_US
dc.subject.pquncontrolledC5aen_US
dc.subject.pquncontrolledCryptococcusen_US
dc.subject.pquncontrolledintravitalen_US
dc.subject.pquncontrolledKupffer cellen_US
dc.subject.pquncontrolledNeutrophilen_US
dc.titleINTRAVASCULAR CLEARANCE OF DISSEMINATING CRYPTOCOCCUS NEOFORMANSen_US
dc.typeDissertationen_US

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