The mere presence of Pseudomonas aeruginosa in the intestine of critically ill surgical patients is associated with a 70% mortality rate--a 3 fold increase above matched patients who culture negative for this pathogen. We propose that within the intestinal tract of a surgically stressed host, physical and chemical environmental signals cause critical shifts in the virulence phenotype of P. aeruginosa. These effects result in a change in the behavior of intestinal P. aeruginosa, causing this bacteria, upon proper cue, to shift from an indolent colonizer to a life-threatening pathogen. In this proposal we provide strong evidence that a virulence determinant in P. aeruginosa, the PA-I lectin/adhesin, plays a key role in lethal gut- derived sepsis in a surgically stressed host. The hypotheses to be tested in this project are: 1) the PA-I lectin of P. aeruginosa is expressed in vivo in response to environmental cues in the intestinal tract including pH, redox state, and norepinephrine following surgical stress (hepatectomy) 2) the PA-I lectin of P.aeruginosa induces an epithelial permeability defect at the level of the intercellular tight junction resulting in paracellular transport of its lethal cytotoxins, and 3) the PA-I lectin of P. aeruginosa alters epithelial tight junctional permeability by activation of regulatory molecules involved in the expression of occludin, the rate limiting seal of the paracellular pathway. We will test these hypotheses using a novel mouse model of endogenous P. aeruginosa sepsis and cultured intestinal epithelial cells that we have extensively studied.
Our specific aims to test these hypotheses are: 1) Determine the expression, location, and function of PA-I in P. aeruginosa harvested from different tissue sites in mice following surgical stress (hepatectomy) and cecal injection of live P. aeruginosa and following in vitro manipulation of the its physical microenvironment (pH, redox, osmolality, norepinephrine). 2) Determine the route of transport of the P. aeruginosa cytotoxins, exotoxin A and elastase, across cultured intestinal epithelial cells (Caco-2) in response to purified PA-I and selected mutants of live P. aeurginosa. 3) Explore potential cellular mechanisms of PA-I-induced decreases in intestinal epithelial barrier function. We propose that we should rethink our understanding of the gut theory of sepsis to include mechanisms by which pathogenic bacteria alter their virulence strategies in response to stressful changes in their local environment. Understanding the virulence determinants and cellular mechanisms that pathogens use to adhere to and modify the intestinal epithelial barrier may lead to therapies which can avoid nosocomial infection at a more proximate point in the care of the critically ill.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
1R01GM062344-01
Application #
6229434
Study Section
Surgery, Anesthesiology and Trauma Study Section (SAT)
Program Officer
Somers, Scott D
Project Start
2001-02-01
Project End
2005-01-31
Budget Start
2001-02-01
Budget End
2002-01-31
Support Year
1
Fiscal Year
2001
Total Cost
$249,751
Indirect Cost
Name
University of Chicago
Department
Surgery
Type
Schools of Medicine
DUNS #
225410919
City
Chicago
State
IL
Country
United States
Zip Code
60637
Alverdy, John C (2018) Hypermetabolism and Nutritional Support in Sepsis. Surg Infect (Larchmt) 19:163-167
Alverdy, John C (2018) Microbiome Medicine: This Changes Everything. J Am Coll Surg 226:719-729
Gaines, S; Shao, C; Hyman, N et al. (2018) Gut microbiome influences on anastomotic leak and recurrence rates following colorectal cancer surgery. Br J Surg 105:e131-e141
Alverdy, John C; Luo, James N (2017) The Influence of Host Stress on the Mechanism of Infection: Lost Microbiomes, Emergent Pathobiomes, and the Role of Interkingdom Signaling. Front Microbiol 8:322
Mao, Jun; Zaborin, Alexander; Poroyko, Valeriy et al. (2017) De Novo Synthesis of Phosphorylated Triblock Copolymers with Pathogen Virulence-Suppressing Properties That Prevent Infection-Related Mortality. ACS Biomater Sci Eng 3:2076-2085
Alverdy, J C; Hyoju, S K; Weigerinck, M et al. (2017) The gut microbiome and the mechanism of surgical infection. Br J Surg 104:e14-e23
Krezalek, Monika A; Yeh, Andrew; Alverdy, John C et al. (2017) Influence of nutrition therapy on the intestinal microbiome. Curr Opin Clin Nutr Metab Care 20:131-137
Gaines, Sara; Alverdy, John C (2017) Fecal Micobiota Transplantation to Treat Sepsis of Unclear Etiology. Crit Care Med 45:1106-1107
Zaborin, Alexander; Krezalek, Monika; Hyoju, Sanjiv et al. (2017) Critical role of microbiota within cecal crypts on the regenerative capacity of the intestinal epithelium following surgical stress. Am J Physiol Gastrointest Liver Physiol 312:G112-G122
Alverdy, John C; Krezalek, Monika A (2017) Collapse of the Microbiome, Emergence of the Pathobiome, and the Immunopathology of Sepsis. Crit Care Med 45:337-347

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