Shigella species are Gram-negative, facultative intracellular enteric bacteria that specifically infect and cause disease in the large intestine of human hosts. Shigella spp. are the causative agent of bacillary dysentery (shigellosis) and the majority of infections occur in countries with inadequate health care and unsafe food and water supplies;however. Shigella outbreaks are a significant problem for industrialized nations as well. The signature feature of this disease is exhibited by an intense inflammatory reaction manifested clinically as passage of bloody stools. This project focuses on novel strategies used by S. flexneri to promote tissue invasion, which elicits the inflammatory response leading to PMN recruitment. Contrary to current dogma, we hypothesize that speciflc bacteria-host interactions that occur at the apical epithelial surface of I EC are critical for Shigella pathogenesis. To test this hypothesis.
Specific Aim 1 will dissect the molecular mechanisms by which S. flexneri regulates the tight junction proteins. The goal of this aim will be to determine the S. flexneri genes that regulate the specific tight junction proteins ZO-1 and ZO-2.
In Specific Aim 2 we will determine how the Shigella secreted protein, SepA, promotes tissue invasion and disease pathogensis from the apical surface: SepA is the major protein secreted by S. flexneri (in vitro), and is an autotransporter serine protease encoded by the virulence plasmid.
This aim will examine important interactions that occur between SepA and the lEC apical surface, which are critical for the ability of S. flexneri to elicit a pro-inflammatory response leading to the recruitment of PMN. Finally, in Specific Aim 3, we will determine the molecular mechanism by which S. flexneri governs HXA3 efflux from the apical membrane domain during S.flexneri infection. We speculate that HXAS is required for neutrophilic breach of the intestinal epithelium during S. flexneri infection. Therefore, understanding the molecular mechanisms that orchestrate the apical release of HXAS will be crucial to designing improved therapies to augment host defense and attenuate detrimental intestinal inflammation during Shigella infection. Ultimately, understanding the molecular mechanisms of S. flexneri entry and induction of pro-inflammatory responses will provide to new insights for controlling the massive inflammatory pathology underiying shigellosis.

Public Health Relevance

Shigella is a major cause of diarrhea, dysentery, and morbidity worldwide. S. flexneri is also a CDC/NIAID Category B priority pathogen that causes disease by invading and spreading through the colonic mucosa. The goal of this proposal is to understand the molecular mechanisms by which S. flexneri invades the colonic epithelium and subsequently triggers/controls the directed movement of PMN across the epithelial surface so that novel targets for therapeutic intervention in inflammatory Shigella infection can be identified.

Agency
National Institute of Health (NIH)
Type
Research Program Projects (P01)
Project #
5P01DK033506-29
Application #
8727516
Study Section
Special Emphasis Panel (ZDK1)
Project Start
Project End
Budget Start
Budget End
Support Year
29
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Massachusetts General Hospital
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
01655
Houghteling, Pearl D; Walker, W Allan (2015) Why is initial bacterial colonization of the intestine important to infants' and children's health? J Pediatr Gastroenterol Nutr 60:294-307
Carter, Edward A; Paul, Kasie; Bonab, Ali A et al. (2014) Effect of exercise on burn-induced changes in tissue-specific glucose metabolism. J Burn Care Res 35:470-3
Carter, Edward A; Hamrahi, Victoria; Paul, Kasie et al. (2014) Single hind limb burn injury to mice alters nuclear factor-?B expression and [ยน?F] 2-fluoro-2-deoxy-D-glucose uptake. J Burn Care Res 35:e373-8
Sharkey, Keith A; Savidge, Tor C (2014) Role of enteric neurotransmission in host defense and protection of the gastrointestinal tract. Auton Neurosci 181:94-106
Walker, Allan (2014) Intestinal colonization and programming of the intestinal immune response. J Clin Gastroenterol 48 Suppl 1:S8-11
Mallick, Emily M; Garber, John J; Vanguri, Vijay K et al. (2014) The ability of an attaching and effacing pathogen to trigger localized actin assembly contributes to virulence by promoting mucosal attachment. Cell Microbiol 16:1405-24
Wang, Lihong; Cao, Hailong; Liu, Liping et al. (2014) Activation of epidermal growth factor receptor mediates mucin production stimulated by p40, a Lactobacillus rhamnosus GG-derived protein. J Biol Chem 289:20234-44
Chiang, Hao-Sen; Zhao, Yun; Song, Joo-Hye et al. (2014) GEF-H1 controls microtubule-dependent sensing of nucleic acids for antiviral host defenses. Nat Immunol 15:63-71
Weng, Meiqian; Ganguli, Kriston; Zhu, Weishu et al. (2014) Conditioned medium from Bifidobacteria infantis protects against Cronobacter sakazakii-induced intestinal inflammation in newborn mice. Am J Physiol Gastrointest Liver Physiol 306:G779-87
Weng, M; Walker, W A (2013) The role of gut microbiota in programming the immune phenotype. J Dev Orig Health Dis 4:203-14

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