Clinical Escherichia coli isolates utilize alpha-hemolysin to inhibit in vitro epithelial cytokine production.
Uropathogenic Escherichia coli is the primary cause of urinary tract infections, which affects over 60% of women during their lifetime. UPEC exhibits a number of virulence traits that facilitate colonization of the bladder, including inhibition of cytokine production by bladder epithelial cells. The goal of this study was to identify the mechanism of this inhibition. We observed that cytokine suppression was associated with rapid cytotoxicity toward epithelial cells. We found that cytotoxicity, cytokine suppression and alpha-hemolysin production were all tightly linked in clinical isolates. We screened a UPEC fosmid library and identified clones that gained the cytotoxicity and cytokine-suppression phenotypes. Both clones contained fosmids encoding a PAI II(J96)-like domain and expressed the alpha-hemolysin (hlyA) encoded therein. Mutation of the fosmid-encoded hly operon abolished cytotoxicity and cytokine suppression. Similarly, mutation of the chromosomal hlyCABD operon of UPEC isolate F11 also abolished these phenotypes, and they could be restored by introducing the PAI II(J96)-like domain-encoding fosmid. We also examined the role of alpha-hemolysin in cytokine production both in the murine UTI model as well as patient specimens. We conclude that E. coli utilizes alpha-hemolysin to inhibit epithelial cytokine production in vitro. Its contribution to inflammation during infection requires further study.
Femeris Women's Health Research Center, Medical Diagnostic Laboratories LLC, 2439 Kuser Rd, Hamilton, NJ 08690, USA. dhilbert@mdlab.com
David W
DW
Hilbert
Teresa E
TE
Paulish-Miller
Chee K
CK
Tan
Alison J
AJ
Carey
Glen C
GC
Ulett
Eli
E
Mordechai
Martin E
ME
Adelson
Scott E
SE
Gygax
Jason P
JP
Trama
D000818:Animals; D002999:Clone Cells; D016207:Cytokines / Q000096:biosynthesis*; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D005260:Female; D014644:Genetic Variation; D006460:Hemolysin Proteins / Q000378:metabolism*; D006801:Humans; D051379:Mice; D014552:Urinary Tract Infections / Q000382:microbiology*; D056689:Uropathogenic Escherichia coli / Q000378:metabolism* / Q000472:pathogenicity*; D014774:Virulence / Q000235:genetics
D016207:Cytokines; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; C036507:Hlya protein, E coli