Effect of bacterial virulence on IL-18 expression in the amnion infected with Escherichia coli.
OBJECTIVE
The upregulation of inflammatory substances threatens pregnancy. Interleukin-18 (IL-18) is elevated in women who miscarried. The purpose of this study was to develop a pig model of chorioamnionitis to study the effect of bacterial virulence on IL-18 response in experimentally infected amnion.


METHODS
A total of 20,000 colony-forming units of Escherichia coli (an enteropathogenic O55 strain, EPEC or O86 non-pathogenic strain) were administered into the amniotic cavity of pig fetuses at 70% of gestation for 10 hr. Fetal amniotic fluid samples were analyzed for IL-18 levels by enzyme-linked immunosorbent assay. The expression of IL-18 was studied also by immunohistochemistry on cryostat sections through amniotic membranes and pathological changes were observed by electron microscopy.


RESULTS
Both E. coli strains propagated in amniotic fluids and reached similar counts. Only EPEC, however, caused a significant increase of IL-18 amniotic fluid levels (P < 0.001) and cytokine expression in the amniotic epithelium.


CONCLUSIONS
The levels of IL-18 in infected amniotic fluids correlated with bacterial virulence and pathological changes in the amnion.
Splíchalová
Alla
A
Department of Immunology and Gnotobiology, Institute of Microbiology, Academy of Sciences of the Czech Republic, 549 22 Nový Hrádek, Czech Republic. splichal@biomed.cas.cz
Trebichavský
Ilja
I
Muneta
Yoshihiro
Y
Mori
Yasuyuki
Y
Splíchal
Igor
I
D000650:Amnion / Q000382:microbiology* / Q000648:ultrastructure; D000818:Animals; D004926:Escherichia coli / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000378:metabolism*; D005260:Female; D005455:Fluorescent Antibody Technique; D007150:Immunohistochemistry; D020382:Interleukin-18 / Q000096:biosynthesis / Q000235:genetics*; D046529:Microscopy, Electron, Transmission; D011247:Pregnancy; D013552:Swine; D014774:Virulence
D020382:Interleukin-18