Medicine and Health Sciences Commons^™

The Role Of Intracellular Growth During The Systemic Spread Of Listeria Monocytogenes, Jamila S. Tucker

Theses and Dissertations--Microbiology, Immunology, and Molecular Genetics

Listeria monocytogenes is a facultative intracellular pathogen transmitted through the consumption of contaminated food products. Typically, infections range from mild, self-limiting gastroenteritis to life-threatening systemic infections; however, the events that occur in the gut to allow for this spread are unclear.

The focus of my thesis aims to determine how L. monocytogenes escape the mesenteric lymph nodes (MLN), the final barrier to systemic spread for both commensal and pathogenic bacteria in the gut. I have shown that intracellular replication of L. monocytogenes in an as-yet-unidentified cell type is essential for the colonization and dissemination of the bacteria from the MLN. …

Characterizing The Physiology And Genetics Of Contact Dependent Growth Inhibiton Systems In Burkholderia Species, Alice Elizabeth Oates

Theses and Dissertations--Microbiology, Immunology, and Molecular Genetics

Contact-dependent growth inhibition (CDI) systems mediate interbacterial competition. The genes encoding these systems are widespread among Gram-negative bacteria, including Burkholderia pathogens. CDI systems of Burkholderia species are composed of two-partner secretion pathway proteins and function to deliver the toxic C-terminus of a polymorphic surface-exposed exoprotein BcpA (Burkholderia CDI protein A) to the cytoplasm of neighboring recipient bacteria upon cell-cell contact. Specific outer and inner membrane proteins facilitate BcpA translocation both out of the donor bacterium and into the recipient cell cytoplasm. Most Burkholderia species-specific CDI translocation factors in recipient cells are unknown. BcpA intoxication functions as a mechanism by …

Elucidating The Complex Signaling Events Driving Intestinal Stem Cell Plasticity Following Injury, Evan Lynch

Theses and Dissertations--Microbiology, Immunology, and Molecular Genetics

Signaling events governing intestinal stem cell (ISC) homeostasis maintain the delicate balance of active self-renewal and passive differentiation to replenish intestinal epithelial cells (IEC) every 3-5 days. However, under certain contexts, ISC function is irreversibly compromised—requiring committed IEC lineages to dedifferentiate and regain “stemness”. In the current studies, we examine the signaling events driving epithelial cell responses to injury to expose pathologic failures in the healing response. Our specific goal is to tease out the cellular contexts that promote dedifferentiation to design effective therapeutics for disease conditions compromising ISC function.

First, we generated a novel transgenic animal using the epithelial-specific …

Mast Cells As Novel Effector Cells In The Pathogenesis Of Chronic Graft-Versus-Host Disease, Ethan Strattan

Theses and Dissertations--Microbiology, Immunology, and Molecular Genetics

Hematopoietic stem cell transplantation (HSCT) is most commonly a treatment for inborn defects of hematopoiesis or acute leukemias. Widespread use of HSCT, a potentially curative therapy, is hampered by onset of graft-versus-host-disease (GVHD), a condition wherein the donor cells recognize the patient tissues as non-self. GVHD can manifest anywhere from weeks to decades post-transplant and is classified as either acute or chronic GVHD, both of which are significant causes of transplant-related morbidity and mortality.

However, GVHD is a complex, multifactorial, and enigmatic disease. The factors driving GVHD at the cellular and molecular level are incompletely understood. Immunosuppression targeting T-cells has …

The Role Of Pro-Inflammatory Mediators Ifnβ And Prostaglandin E2 In Suppression Of Innate Immunity To Listeria Monocytogenes, Michelle G. Pitts

Theses and Dissertations--Microbiology, Immunology, and Molecular Genetics

As a foodborne pathogen, Listeria monocytogenes (Lm) encounters many barriers to invasion and dissemination in the host that may change the nature of host response. Lm has been most commonly studied using intravenous (i.v.) inoculation, however, a method that delivers a bolus of bacteria directly to the bloodstream. Thus, little is known about what systemic and local mediators are triggered during the natural course of infection and how these may impact susceptibility. Our laboratory used foodborne transmission of Lm in mice to assess whether the method of transmission and the specific organ microenvironment could affect infection-induced secretion of …