Identification of multiple and distinct defects in prostaglandin biosynthetic pathways in eutopic and ectopic endometrium of women with endometriosis

Abstract

To investigate prostaglandin (PG) biosynthesis and catabolism pathways in eutopic and ectopic endometrium of women with endometriosis. Retrospective study. Human reproduction research laboratory. Forty-five women with endometriosis and 29 normal controls. Endometrial and endometriotic tissue samples were obtained during laparoscopic surgery. Cyclo-oxygenases (Coxs 1 and 2), PGE2 synthases (microsomal [m] PGES 1 and 2 and cytosolic [c] PGES), PGF2α synthases (aldoketoreductase [AKR]-1C3 and AKR-1B1), and the PG catabolic enzyme 15-hydroxyprostaglandin dehydrogenase messenger RNA expression by quantitative real-time polymerase chain reaction and protein localization by immunohistochemistry. This study showed a marked increase in the key PG biosynthesis enzymes Cox-2, mPGES-1, mPGES-2, cPGES, and AKR-1C3 in ectopic endometrial tissue of women with endometriosis, particularly in the earliest and most active stages of the disease, without a noticeable change in the expression of the PG catabolic enzyme 15-hydroxyprostaglandin dehydrogenase. Meanwhile, the significant increase in rate-limiting Cox-2 expression upstream was correlated downstream by a significant stage- and cycle phase-dependent decrease in the terminal specific synthase mPGES-2, thereby revealing the presence of counter-regulatory mechanisms, which operate in the eutopic endometrium of women with endometrium but seem to be lacking in the ectopic implantation sites. This study reveals for the first time multiple defects in PG biosynthesis pathways, which differ between eutopic intrauterine and ectopic endometrial tissues and may, owing to the wide spectrum of PG properties, contribute to the initial steps of endometrial tissue growth and development and have an important role to play in the pathogenesis and symptoms of this disease.