Components of intestinal epithelial hypoxia activate the virulence circuitry of Pseudomonas.
We have previously shown that a lethal virulence trait in Pseudomonas aeruginosa, the PA-I lectin, is expressed by bacteria within the intestinal lumen of surgically stressed mice. The aim of this study was to determine whether intestinal epithelial hypoxia, a common response to surgical stress, could activate PA-I expression. A fusion construct was generated to express green fluorescent protein downstream of the PA-I gene, serving as a stable reporter strain for PA-I expression in P. aeruginosa. Polarized Caco-2 monolayers were exposed to ambient hypoxia (0.1-0.3% O2) for 1 h, with or without a recovery period of normoxia (21% O2) for 2 h, and then inoculated with P. aeruginosa containing the PA-I reporter construct. Hypoxic Caco-2 monolayers caused a significant increase in PA-I promoter activity relative to normoxic monolayers (165% at 1 h; P < 0.001). Similar activation of PA-I was also induced by cell-free apical, but not basal, media from hypoxic Caco-2 monolayers. PA-I promoter activation was preferentially enhanced in bacterial cells that physically interacted with hypoxic epithelia. We conclude that the virulence circuitry of P. aeruginosa is activated by both soluble and contact-mediated elements of the intestinal epithelium during hypoxia and normoxic recovery.
Kohler
Jonathan E
JE
Department of Surgery, University of Chicago, Chicago, Illinois 60637, USA.
Zaborina
Olga
O
Wu
Licheng
L
Wang
Yingmin
Y
Bethel
Cindy
C
Chen
Yimei
Y
Shapiro
James
J
Turner
Jerrold R
JR
Alverdy
John C
JC
D018829:Adhesins, Bacterial / Q000096:biosynthesis* / Q000502:physiology; D018938:Caco-2 Cells; D015687:Cell Hypoxia / Q000502:physiology; D017930:Genes, Reporter; D006801:Humans; D007413:Intestinal Mucosa / Q000382:microbiology / Q000503:physiopathology*; D037102:Lectins / Q000096:biosynthesis* / Q000502:physiology; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000472:pathogenicity*; D013997:Time Factors; D014774:Virulence
D018829:Adhesins, Bacterial; D037102:Lectins; C038692:adhesin, Pseudomonas