Pseudomonas aeruginosa expresses a lethal virulence determinant, the PA-I lectin/adhesin, in the intestinal tract of a stressed host: the role of epithelia cell contact and molecules of the Quorum Sensing Signaling System.
OBJECTIVE
We have previously demonstrated that P. aeruginosa can have profound effects on the intestinal epithelial barrier via one of its virulence factors, the PA-I lectin/adhesin. The aims of the present study were to further characterize the interaction of P. aeruginosa and the intestinal epithelium using both in vitro and in vivo approaches.


METHODS
In vitro assays examining the effect of bacterial growth phase, epithelial cell contact, and butanoyl homoserine lactone (C4-HSL), a quorum sensing signaling molecule know to affect various extracellular virulence factors in P. aeruginosa, on PA-I expression in P. aeruginosa were performed. In vivo studies were carried out by modeling catabolic stress in mice using a 30% surgical hepatectomy and direct introduction of P. aeruginosa and various virulence components into the cecum. The effect of this model on PA-I expression in P. aeruginosa was determined.


RESULTS
Results demonstrated that PA-I expression in P. aeruginosa is affected by its phase of growth, its contact to the intestinal epithelium, and its exposure to the quorum sensing molecule, C4-HSL. Furthermore, data from the present study suggest that the PA-I lectin/adhesin of P. aeruginosa may be increased in vivo by local factors within the cecum of mice in response to surgical stress.


CONCLUSIONS
These data indicate that multiple factors present in the intestinal microenvironment of a stressed host may induce certain opportunistic pathogens to express key virulence factors leading to a state of lethal gut-derived sepsis.
Department of Surgery and Medicine, University of Chicago, Chicago, IL, USA.
Licheng
L
Wu
Christopher
C
Holbrook
Olga
O
Zaborina
Emelia
E
Ploplys
Flavio
F
Rocha
Daniel
D
Pelham
Eugene
E
Chang
Mark
M
Musch
John
J
Alverdy
D018829:Adhesins, Bacterial / Q000032:analysis / Q000235:genetics*; D000818:Animals; D018938:Caco-2 Cells; D002432:Cecum / Q000382:microbiology; D016638:Critical Illness; D004195:Disease Models, Animal; D017097:Electric Impedance; D004847:Epithelial Cells / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D006498:Hepatectomy; D006801:Humans; D007413:Intestinal Mucosa / Q000382:microbiology*; D037102:Lectins / Q000032:analysis / Q000235:genetics*; D051379:Mice; D008807:Mice, Inbred BALB C; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000472:pathogenicity*; D018805:Sepsis / Q000235:genetics / Q000382:microbiology; D013312:Stress, Physiological / Q000382:microbiology*; D014774:Virulence
D018829:Adhesins, Bacterial; D037102:Lectins; C038692:adhesin, Pseudomonas