Escherichia coli (E. coli) is the most frequent bacterium isolated in cases of cystic
endometrial hyperplasia-pyometra complex, the most frequent endometrial disorder in
the bitch. Toll-like receptors (TLRs) play an essential role in the innate immune
system. The aim of this study was to compare transcription of genes encoding TLR2,
TLR4 and LPS ligands (CD14, MD-2, LBP), prostaglandin synthesis enzymes (COX1, COX2,
PGES1 and PGFS), and to compare COX1 and COX2 protein expression and PGE(2) and PGF(2alpha)
endometrial content in the endometrium of canine diestrous uteri with (n=7) or without
(n=7) pyometra. All cases of pyometra were hyperplastic and E. coli was the only isolated
bacteria, while diestrous normal uteri did not present signs of cystic endometrial
hyperplasia and were negative for bacteriology. Except for COX1, transcription of
all genes was significantly higher in pyometra than in normal endometria. COX1 protein
was observed in both normal and pyometra uteri, but COX2 protein was only present
in pyometra cases. Endometrial PGE(2) and PGF(2alpha) content were significantly higher
in pyometra than in normal diestrous endometria. In conclusion, data obtained in this
study provides evidence that pyometra-isolated E. coli induces the up-regulation of
TLR2 and TLR4 genes in the canine diestrous endometrium. This up-regulation, which
is probably the result of the stimulation by LPS and lipoprotein E. coli constituents,
leads to the endometrial up-regulation of PG synthesis genes. This, in turn, results
in a higher endometrial concentration of PGE(2) and PGF(2alpha), which may further
regulate the local inflammatory response.
2009 Elsevier Ireland Ltd. All rights reserved.