Endometrial Stromal and Epithelial Cells Exhibit Unique Aberrant Molecular Defects in Patients With Endometriosis.

Context: Endometriosis is a chronic inflammatory disease that causes pain and infertility in women of reproductive age.

Objective: To investigate the pathologic pathways in endometrial stromal and epithelial cells that contribute to the manifestation of endometriosis.

Design: In vitro cellular and molecular analyses of isolated eutopic endometrial stromal and epithelial cells.

Methods: Eutopic stromal and epithelial cells from endometriotic and normal patients were isolated by fluorescence-activated cell sorting for paired sibling RNA sequencing and microRNA microarray. Aberrant pathways were identified using ingenuity pathway analysis networks and confirmed with in vitro modulation of the affected pathways in stromal and epithelial cell cultures.

Results: Both stromal versus epithelial cell types and paired endometriotic versus normal samples exhibited distinct hierarchical clustering. Compared to normal samples, there were 151 and 215 differentially expressed genes in the endometriotic stromal and epithelial populations, respectively, and concomitantly 9 and 16 differentially expressed microRNAs. Overall, endometriotic stromal and epithelial cells revealed distinct defects. In endometriotic stromal cells, key decidualization genes Zinc finger E-box Binding protein 1 (ZEB1), Heart And Neural crest Derivatives expressed 2 (HAND2), WNT4, and Interleukin 15 (IL-15) were found to be downregulated and Periostin (POSTN) and Matrix Metallopeptidase 7 (MMP7) were upregulated. Specifically, ZEB1 was downregulated in stromal cells by aberrant elevation in miR-200b. In contrast, ZEB1 was found to be upregulated in endometriotic epithelial cells through associated upregulation of transforming growth factor β1 (TGFβ1), inducer of the TGFβ1-Bone Morphogenetic Protein 2 (BMP2)-MMP2-Prostaglandin-endoperoxide Synthase 2 (COX2)-ZEB1 pathway, which activates epithelial-mesenchymal transition.

Conclusion: Manifestation of endometriosis involves dysregulation of unique molecular pathways within the diseased endometrial stromal and epithelial cells in the endometrium. Targeting the cell type-specific defects may offer a novel approach to treating endometriosis.