Reduced eutopic endometrial LIF, LIFR and gp130 protein expression may be associated with subfertility in women with minimal-mild endometriosis. Combined surgical and goserelin acetate treatment does not seem to restore the expression of these members of the IL-6 cytokine superfamily. Elevated peritoneal fluid levels of IL-1α and IL-6 may further contribute to the difficulties of achieving pregnancy in these patients.

Endometriosis affects fertility in many women and may partly be due to decreased endometrial receptivity. Several mechanisms have been suggested, notably, progesterone resistance for which a number of candidate biomarkers have been suggested. Here we demonstrate aberrant levels of steroid hormone receptors and the small heat shock protein αB-crystallin in eutopic endometrial epithelium from 38 women with peritoneal endometriosis diagnosed during investigation for secondary infertility. Spontaneous pregnancies within 1 year after medical and surgical treatment for endometriosis were recorded and semi-quantitative immunohistochemistry data compared between women with endometriosis who did or did not become pregnant and healthy controls. Stronger immunostaining for ER-α was detected in luminal and glandular endometrial epithelium from women with endometriosis who did not become pregnant during the post-treatment observation period versus endometriosis patients who became pregnant and controls. Staining levels of PR and PR-B were lower in patients without subsequent pregnancies than in the two other groups. Endometrial levels of αB-crystallin in endometriosis patients similar to those in controls were strongly correlated with the chance of becoming pregnant, whereas higher or lower levels were not.

Vasoactive intestinal peptide is upregulated in endometriosis patients reporting chronic pain. Increased microvessel density in tissue and peritoneal fluid concentrations of IL-6 indicate an elevated inflammation in the pelvic microenvironment of these patients.

The changes in transcript profile induced by vascular endothelial growth factor (VEGF-A) and serum withdrawal in primary human endometrial endothelial cells (ECs) were investigated using microarrays, gene ontology and pathway analysis. Vascular endothelial growth factor A altered the levels of transcripts involved in angiogenesis, cell survival, and apoptosis, including up-and downregulation of AKT1, BAD, MIF, and IGFBP3 and ANGPT2, respectively. Serum deprivation induced downregulation of cell-cycle-related transcripts such as mitosis regulators CDC20 and SPC25. Of the transcripts regulated by both VEGF-A and partial serum deprivation, remarkably 88 of 89 showed reciprocal regulation (p < 1 x 10(-49)). These are predominantly cell-fate-associated transcripts and this novel observation suggests that endometrial ECs may be particularly dependant on the levels of these transcripts. Our results show that in addition to the known role of VEGF-A as an EC growth and survival promoter, it also regulates apoptosis-related messenger RNAs (mRNAs), many of which were reciprocally regulated following serum withdrawal.

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