Macrophage Migration Inhibitory Factor Receptor, CD74, is Overexpressed in Human and Baboon ( Papio Anubis) Endometriotic Lesions and Modulates Endometriotic Epithelial Cell Survival and Interleukin 8 Expression

The Known, the Unknown and the Future of the Pathophysiology of Endometriosis

Endometriosis is one of the most common causes of chronic pelvic pain and infertility, affecting 10% of women of reproductive age. A delay of up to 9 years is estimated between the onset of symptoms and the diagnosis of endometriosis. Endometriosis is currently defined as the presence of endometrial epithelial and stromal cells at ectopic sites; however, advances in research on endometriosis have some authors believing that endometriosis should be re-defined as "a fibrotic condition in which endometrial stroma and epithelium can be identified". There are several theories on the etiology of the disease, but the origin of endometriosis remains unclear. This review addresses the role of microRNAs (miRNAs), which are naturally occurring post-transcriptional regulatory molecules, in endometriotic lesion development, the inflammatory environment within the peritoneal cavity, including the role that cytokines play during the development of the disease, and how animal models have helped in our understanding of the pathology of this enigmatic disease.

Soluble Factors CD14, CD163, and Migration Inhibitory Factor Are Associated with Endometriosis-Related Infertility

OBJECTIVES

Myeloid cell-derived factors contribute to the immunopathology of endometriosis. Soluble CD14 (sCD14), CD163 (sCD163), and MIF serve as in vivo markers of myeloid function. However, these soluble molecules are largely unexplored in women with endometriosis-related infertility cases. We investigated three soluble markers, namely sCD14, sCD163, and MIF, in cases of infertility associated with endometriosis and correlated its level to the stage of endometriosis.

DESIGN

Eighty-seven women newly diagnosed with endometriosis or other benign gynecologic control cases linked to infertility were prospectively recruited and underwent diagnostic laparoscopy.

PARTICIPANTS

Forty-four patients with endometriosis were included in this study, comprising 19 patients with early-endometriosis (stages I and II) and 25 late-endometriosis (stages III and IV) based on the revised American Society for Reproductive Medicine (rASRM) classification. The remaining 43 patients constituted a control group with infertility due to other causes.

METHODS

The levels of sCD14, sCD163, and MIF in serum and peritoneal fluid were assessed using ELISA.

RESULTS

Endometriosis women exhibited significantly higher serum levels of sCD163 and MIF levels compared to the control group. Both sCD163 and MIF levels displayed a positive correlation with the rASRM adhesion score. Moreover, the MIF level in serum had a positive correlation with the rASRM endometriosis score. In receiver operating characteristic analysis, serum sCD163 and MIF could significantly discriminate endometriosis and non-endometriosis in infertility cases.

LIMITATIONS

Some limitations of the current study deserve to be underlined. First, the sensitive ELISA method was the sole-validated tool for detecting the markers in patient samples. Second, healthy or fertile women were not involved as the control group.

CONCLUSIONS

The elevated systemic levels of sCD163 and MIF correlated with the severity of endometriosis. These soluble molecules have a potential diagnostic capacity as a non-invasive biomarker. Furthermore, our data warrants future studies on the underlying mechanism of sCD163 and MIF in endometriosis-related infertility.

Dissecting the miR-451a-Mif Pathway in Endometriosis Pathophysiology Using a Syngeneic Mouse Model: Temporal Expression of Lesion Mif Receptors, Cd74 and Cxcr4

Endometriosis is an enigmatic disease characterized by pain and infertility in which endometrial tissue grows in ectopic locations, predominantly the pelvic cavity. The pathogenesis and pathophysiology of endometriosis is complex and postulated to involve alterations in inflammatory, cell proliferation and post-transcriptional regulatory pathways among others. Our understanding on the pathogenesis and pathophysiology of endometriosis is further complicated by the fact that endometriosis can only be diagnosed by laparoscopy only after the disease has manifested. This makes it difficult to understand the true pathogenesis as a cause-and-effect relationship is difficult to ascertain. To aid in our understanding on endometriosis pathogenesis and pathophysiology, numerous rodent models have been developed. In this case, we discuss further assessment of a miR-451a-macrophage migration inhibitory factor (Mif) pathway which contributes to lesion survival. Specifically, we evaluate the temporal expression of lesion Mif receptors, Cd74 and Cxcr4 using host mice which express wild-type or miR-451a deficient lesions. Similar to that observed in humans and a non-human primate model of endometriosis, Cd74 expression is elevated in lesion tissue in a temporal fashion while that of Cxcr4 shows minimal increase during initial lesion establishment but is reduced later during the lifespan. Absence of miR-451a during initial lesion establishment is associated with an augmentation of Cd74, but no Cxcr4 expression. The data obtained in this study provide further support for a role of Mif receptors, Cd74 and Cxcr4 in the pathophysiology of endometriosis.

Macrophage migration inhibitory factor modulates cytokine expression in the trophoblast cell line HTR-8/SVneo

Extravillous trophoblasts are specific placental cells that invade the uterine stroma and spiral arteries modifying and adjusting them to pregnancy. Many pregnancy pathologies are associated with impairment of this process, including preeclampsia and intrauterine growth restriction, among others. Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine that is abundant at the fetomaternal interface. Previous results from our group showed that MIF participates in trophoblast invasion and modulates the expression of molecules known to mediate stromal and endovascular trophoblast invasion. In this study we investigated the possibility that MIF could act as a regulator of cytokines known to modulate trophoblast invasion using the normal extravillous trophoblast-derived cell line HTR-8/SVneo. Expression of trophoblast MIF was attenuated by MIF mRNA-specific small interfering RNAs. Cytokine expression was assessed at the mRNA and protein levels using real-time quantitative polymerase chain reaction and flow cytometry respectively. Knockdown of MIF led to a significant decrease in mRNA for IL-1β (IL1B) and IL-8 (CXCL8) and interleukin (IL)-8 protein. The addition of recombinant human MIF to cell culture medium increased IL-6 after 24h treatment and IL-6 and IL-8 after 72h treatment. Cell viability was not affected by MIF silencing or rhMIF treatment. The results of this study imply that at least some of the effects of MIF on trophoblast invasion could be mediated through autocrine or paracrine modulation of trophoblast cytokine production.

Increased CXCL12 expression in endometrium of women with abnormal uterine bleeding is post-transcriptionally mediated via miR-23b-3p and is associated with decreased expression of the miR-23b-3p/24-3p/27b-3p cluster: a pilot study

OBJECTIVE

To study C-X-C motif chemokine 12 (CXCL12) and CXCR4 expression in endometrial tissue from both women with and without abnormal uterine bleeding (AUB) of endometrial origin and evaluate their relationship with microRNA (miRNA).

DESIGN

Retrospective and laboratory study.

SETTING

University-based research laboratory.

PATIENT(S)

Nine women with and without abnormal uterine bleeding, all of whom were in the secretory stage of their menstrual cycle, who provided endometrial biopsy tissue.

INTERVENTION(S)

Immunohistochemical localization of CXCL12 and CXCR4 as well as quantitative reverse-transcription polymerase chain reaction (qRT-PCR) assessment of mRNA expression in archived endometrial biopsy tissue and in vitro cell culture using the immortalized endometrial stromal cell line, t-HESC. Endometrial stromal cell line, t-HESC transfection with nontargeting, negative control miRNA mimics or miRNA mimics for miR-23b-3p and mRNA assessment miR-23b-3p expression confirmed by qRT-PCR and evaluation of impact on CXCL12 expression at the protein level by enzyme-linked immunosorbent assay and mRNA levels by qRT-PCR.

MAIN OUTCOME MEASURE(S)

Expression of CXCL12 and CXCR4 protein via immunohistochemistry and mRNA and miRNA levels of CXCL12 and CXCR4 as well as miR-23b-3p, miR-24b-3p, and miR-27b-3p, respectively, via qRT-PCR.

RESULT(S)

CXCL12 and its receptor CXCR4 expression were up-regulated in the endometrial tissue of women with AUB at the protein level, but this up-regulation of expression was only associated with increased CXCR4 mRNA expression. To evaluate whether CXCL12 may be post-transcriptionally regulated, we assessed expression of miR-23b-3p, a bona fide post-transcriptional regulator of CXCL12 expression. The expression of miR-23b-3p was statistically significantly lower in AUB endometrial tissue, as were fellow cluster members miR-24-3p and miR-27-3p. Transfection of t-HESC cells with pre-miR-23b-3p mimics statistically significantly reduced the levels of CXCL12 secreted protein but not mRNA levels, suggesting that miR-23b-3p retards protein translation independent of transcript degradation.

CONCLUSION(S)

Reduced expression of the miR-23b-3p/24-3p/27b-3p cluster is associated with elevated expression of CXCL12, which may contribute to the pathophysiology of AUB.

Concurrent Immunohistochemical Localization and Western Blot Analysis of the MIF Receptor, CD74, in Formalin-Fixed, Paraffin-Embedded Tissue

Archived, formalin-fixed, paraffin-embedded tissue provides a robust resource for assessing protein expression in a variety of complex tissue types. Immunohistochemical localization techniques allow one to identify proteins of interest in the different cell populations which compose these tissues, but quantitative comparison within and between samples is semiquantitative. In contrast, Western blot analysis provides a more quantitative assessment but without the ability to identify the cellular sources of expressed protein. Here we describe a dual approach using human endometrium to assess both the localization and quantitation of the macrophage migration inhibitory factor (MIF) receptor CD74 by immunohistochemical techniques and Western blotting.

Human endometriotic lesion expression of the miR-144-3p/miR-451a cluster, its correlation with markers of cell survival and origin of lesion content

Endometriosis is an inflammatory condition in which endometrial tissue grows in ectopic locations. Survival and growth of these ectopic lesions is associated with pain and infertility. MicroRNAs (miRNAs) have been postulated to play a role in the pathophysiology of the disease and we have previously demonstrated expression of miR-451 in human endometriotic lesion tissue. Here we report elevated expression of the miR-144-3p/miR-451a cluster in human endometriotic lesion tissue. Use of an endometriotic epithelial cell line (12Z) in which the miRNA processing enzyme, DROSHA, was knocked down resulted in an enrichment in the primary (pri) form of miR-144-3p but not that of pri-miR-451a. Using an experimental mouse model of endometriosis in which ectopic endometriotic lesions were deficient for both of these miRNAs revealed that miR-451a, but not miR-144-3p may be derived from exogenous sources such as the circulation/erythrocytes. Together, these data suggest that the miR-144-3p/miR-451a cluster is expressed in human endometriotic lesion tissue, the level of expression correlates with survival status of the lesion tissue and that miR-451a, but not miR-144-3p may be derived from exogenous sources such as erythrocytes.