Mechanisms Utilized by Neisseria gonorrhoeae to Persist in the Human Cervical Epithelium: Signaling, Invasion, Intracellular Survival, and Escape

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dc.contributor.advisorStein, Daniel Cen_US
dc.contributor.authorBish, Samuel Earlen_US
dc.contributor.departmentCell Biology & Molecular Geneticsen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2008-04-22T16:02:55Z
dc.date.available2008-04-22T16:02:55Z
dc.date.issued2007-11-07en_US
dc.description.abstractThe obligate human pathogen <em>Neisseria gonorrhoeae</em> (gonococci) causes the sexually transmitted disease gonorrhea. Interactions between gonococci and human cervical epithelial cells that promote bacterial invasion and post-invasion survival were examined. The data showed that gonococci activated MAPK signaling in cervical epithelial cells prior to invasion. Gonococci triggered prolonged ERK phosphorylation (possibly through EGFR signaling), which could facilitate gonococcal invasion. Furthermore, gonococci expressing lacto-<em>N</em>-neotetraose LOS decreased JNK activation and elicited lower IL-8 production from host cells compared to variants expressing lactosyl LOS. I propose that gonococci can manipulate MAPK signaling to facilitate invasion into cervical epithelial cells and to evade the innate immune response. To investigate gonococcal invasion, I expressed β-lactamase on the outer membrane of gonococcal strain FA1090 to generate the reporter strain FA1090 psi(bla-iga'). Utilizing a β-lactamase reporter assay, I demonstrated that FA1090 psi(bla-iga') only invaded a subpopulation of cervical epithelial cells. Nonviable FA1090 psi(bla-iga') did not invade host cells and failed to recruit F-actin to sites of adherence. Viable gonococci required pili expression but not Opa expression to invade susceptible host cells. These data suggest that viable gonococci elicit invasion-promoting interactions with host cells not triggered by nonviable gonococci. Finally, the data demonstrated that gonococci realize different intracellular fates after entry into cervical epithelial cells. I developed a tannic acid survival assay to show that intracellular gonococci survived within host cells. Intracellular survival did not require catalase or the NfsB nitrogen reductase. A subpopulation of gonococci could escape from cells back into the extracellular milieu. Gonococci utilized an exocytosis pathway to escape after invasion that was blocked by treating cells with tannic acid, but not cytoskeletal inhibitors. I propose a working scenario whereby gonococci undergo cycles of invasion into and escape from a susceptible subpopulation of cervical epithelial cells. Gonococci that survive within host cells may represent bacteria that progress into deeper host tissues to disseminate to secondary sites. Escaping gonococci could invade into other host cells and are well-positioned for transmission to another host. Gonococci interact with the cervical epithelium through invasion, intracellular survival, and escape to establish bacterial persistence in the female host.en_US
dc.format.extent22057046 bytes
dc.format.mimetypeapplication/pdf
dc.identifier.urihttp://hdl.handle.net/1903/7637
dc.language.isoen_US
dc.subject.pqcontrolledBiology, Microbiologyen_US
dc.subject.pqcontrolledBiology, Cellen_US
dc.subject.pqcontrolledBiology, Geneticsen_US
dc.subject.pquncontrolledNeisseria gonorrhoeaeen_US
dc.subject.pquncontrolledinvasionen_US
dc.subject.pquncontrolledsignalingen_US
dc.subject.pquncontrolledintracellular survivalen_US
dc.subject.pquncontrolledescapeen_US
dc.subject.pquncontrolledbeta-lactamaseen_US
dc.titleMechanisms Utilized by Neisseria gonorrhoeae to Persist in the Human Cervical Epithelium: Signaling, Invasion, Intracellular Survival, and Escapeen_US
dc.typeDissertationen_US

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