Peritoneal fluid modifies the microRNA expression profile in endometrial and endometriotic cells from women with endometriosis

STUDY QUESTION

Could peritoneal fluid (PF) from patients with endometriosis alter the microRNA (miRNA) expression profile in endometrial and endometriotic cells from patients?

SUMMARY ANSWER

PF from patients with endometriosis modifies the miRNA expression profile in endometrial cells from patients.

WHAT IS KNOWN ALREADY

Angiogenesis is a pivotal system in the development of endometriosis, and dysregulated miRNA expression in this disease has been reported. However, to our knowledge, the effect of PF from patients on the miRNA expression profile of patient endometrial cells has not been reported. Moreover, an effect of three miRNAs (miR-16-5p, miR-29c-3p and miR-424-5p) on the regulation of vascular endothelial growth factor (VEGF)-A mRNA translation in endometrial cells from patients with endometriosis has not been demonstrated.

STUDY DESIGN, SIZE, DURATION

Primary cultures of stromal cells from endometrium from 8 control women (control cells) and 11 patients with endometriosis (eutopic cells) and ovarian endometriomas (ectopic cells) were treated with PF from control women (CPF) and patients (EPF) or not treated (0PF) in order to evaluate the effect of PF on miRNA expression in these cells.

PARTICIPANTS/MATERIALS, SETTING, METHODS

MiRNA expression arrays (Affymetrix platform) were prepared from cells (control, eutopic, ectopic) treated with CPF, EPF or 0PF. Results from arrays were validated by quantitative reverse transcription-polymerase chain reaction in cultures from 8 control endometrium, 11 eutopic endometrium and 11 ovarian endometriomas. Functional experiments were performed in primary cell cultures using mimics for miRNAs miR-16-5p, miR-29c-3p and miR-424-5p to assess their effect as VEGF-A expression regulators. To confirm a repressive action of miR-29c-3p through forming miRNA:VEGFA duplexes, we performed luciferase expression assays.

MAIN RESULTS AND THE ROLE OF CHANCE

EPF modified the miRNA expression profile in eutopic cells. A total of 267 miRNAs were modified in response to EPF compared with 0PF in eutopic cells. Nine miRNAs (miR-16-5p, miR-21-5p, miR-29c-3p, miR-106b-5p, miR-130a-5p, miR-149-5p, miR-185-5p, miR-195-5p, miR-424-5p) that were differently expressed in response to EPF, and which were potential targets involved in angiogenesis, proteolysis or endometriosis, were validated in further experiments (control = 8, eutopic = 11, ectopic = 11). Except for miR-149-5p, all validated miRNAs showed significantly lower levels (miR-16-5p, miR-106b-5p, miR-130a-5p; miR-195-5p and miR-424-5p, P < 0.05; miR-21-5p, miR-29c-3p and miR-185-5p, P < 0.01) after EPF treatment in primary cell cultures from eutopic endometrium from patients in comparison with 0PF. Transfection of stromal cells with mimics of miRNAs miR-16-5p, miR-29c-3p and miR-424-5p showed a significant down-regulation of VEGF-A protein expression. However, VEGFA mRNA expression after mimic transfection was not significantly modified, indicating the miRNAs inhibited VEGF-A mRNA translation rather than degrading VEGFA mRNA. Luciferase experiments also corroborated VEGF-A as a target gene of miR-29c-3p.

LIMITATIONS, REASONS FOR CAUTION

The study was performed in an in vitro model of endometriosis using stromal cells. This model is just a representation to try to elucidate the molecular mechanisms involved in the development of endometriosis. Further studies to identify the pathways involved in this miRNA expression modification in response to PF from patients are needed.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first study describing a modified miRNA expression profile in eutopic cells from patients in response to PF from patients. These promising results improve the body of knowledge on endometriosis pathogenesis and could open up new therapeutic strategies for the treatment of endometriosis through the use of miRNAs.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by research grants by ISCIII and FEDER (PI11/00091, PI11/00566, PI14/01309, PI14/00253 and FI12/00012), RIC (RD12/0042/0029 and RD12/0042/0050), IIS La Fe 2011-211, Prometeo 2011/027 and Contrato Sara Borrell CD13/0005. There are no conflicts of interest to declare.

MicroRNAs and angiogenesis in endometriosis

miRNAs function as important regulators of a wide range of cellular processes, such as angiogenesis and fibrinolysis, by postranscriptional modulation of gene expression. We present a review on the role of miRNAs and angiogenesis in endometriosis. Endometriosis, defined as the implantation of endometrial tissue outside the uterine cavity, is one of the most frequent benign gynecological diseases and it has important consequences on the quality of life and fertility of patients. Similarly to tumor metastasis, the ectopic endometrium acquires the capability to adhere, proliferate and infiltrate the extracellular matrix. Endometriosis is a multifactorial and polygenic disease in which angiogenesis and proteolysis may be involved, and emerging data provide evidence that a dysregulation of miRNA expression may be implicated in these processes. The detection of circulating miRNAs in plasma and other body fluids and their relative stability has raised the possibility that they might serve as non-invasive biomarkers for the diagnosis of the disease. On the other hand, the development of therapies that might block the expression or mimic the functions of miRNAs could represent new therapeutic strategies for the treatment of endometriosis.

MicroRNA expression profile in endometriosis: its relation to angiogenesis and fibrinolytic factors

STUDY QUESTION

Could an aberrant microRNA (miRNA) expression profile be responsible for the changes in the angiogenic and fibrinolytic states observed in endometriotic lesions?

SUMMARY ANSWER

This study revealed characteristic miRNA expression profiles associated with endometriosis in endometrial tissue and endometriotic lesions from the same patient and their correlation with the most important angiogenic and fibrinolytic factors. WHAT IS ALREADY KNOWN?: An important role for dysregulated miRNA expression in the pathogenesis of endometriosis is well documented. However, to the best of our knowledge, there are no reports of the relationship between angiogenic and fibrinolytic factors and miRNAs when endometrial tissue and different types of endometriotic lesions from the same patient are compared.

STUDY DESIGN, SIZE, DURATION

Case-control study that involved 51 women with endometriosis and 32 women without the disease (controls).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The miRNA expression profiles were determined using the GeneChip miRNA 2.0 Affymetrix array platform, and the results were analysed using Partek Genomic Suite software. To validate the obtained results, 12 miRNAs differentially expressed were quantified by using miRCURY LNA™ Universal RT microRNA PCR. Levels of vascular endothelial growth factor (VEGF-A), thrombospondin-1 (TSP-1), urokinase plasminogen activator (uPA) and plasminogen activator inhibitor-1 (PAI-1) proteins were quantified by ELISA.

MAIN RESULTS AND THE ROLE OF CHANCE

Patient endometrial tissue showed significantly lower levels of miR-202-3p, miR-424-5p, miR-449b-3p and miR-556-3p, and higher levels of VEGF-A and uPA than healthy (control) endometrium. However, tissue affected by ovarian endometrioma showed significantly lower expression of miR-449b-3p than endometrium from both controls and patients, and higher levels of PAI-1 and the angiogenic inhibitor TSP-1. A significant inverse correlation between miR-424-5p and VEGF-A protein levels was observed in patient endometrium, and an inverse correlation between miR-449b-3p and TSP-1 protein levels was observed in ovarian endometrioma. Peritoneal implants had significantly higher levels of VEGF-A than ovarian endometrioma samples.

LIMITATIONS, REASONS FOR CAUTION

Functional studies are needed to confirm the specific targets of the miRNAs differently expressed.

WIDER IMPLICATIONS OF THE FINDINGS

Differences in miRNA levels could modulate the expression of VEGF-A and TSP-1, which may play an important role in the pathogenesis of endometriosis. The higher angiogenic and proteolytic activities observed in eutopic endometrium from patients might facilitate the implantation of endometrial cells at ectopic sites.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by research grants from ISCIII-FEDER (PI11/0091, Red RIC RD12/0042/0029), Consellería de Educación-Generalitat Valenciana (PROMETEO/2011/027), Beca de Investigación Fundación Dexeus para la Salud de la Mujer (2011/0469), and by Fundación Investigación Hospital La Fe (2011/211). A.B-B. has a Contrato Posdoctoral de Perfeccionamiento Sara Borrell-ISCIII (CD13/00005). J.M-A. has a predoctoral grant PFIS-ISCIII (FI12/00012). The authors have no conflicts of interest to declare.

Functional Analysis of Two Haplotypes of the Human Endothelial Protein C Receptor Gene

Objective—

To confirm the effect of the endothelial protein receptor gene ( PROCR ) haplotypes H1 and H3 on venous thromboembolism (VTE), to study their effect on endothelial protein C receptor (EPCR) expression in human umbilical vein endothelial cells, and to investigate the functionality of H1 tagging single-nucleotide polymorphisms in an in vitro model.

Approach and Results—

Protein C (PC), activated PC, and soluble EPCR (sEPCR) levels were measured in 702 patients with VTE and 518 healthy individuals. All subjects were genotyped for PROCR H1 and H3. Human umbilical vein endothelial cells isolated from 111 umbilical cords were used to study the relation between PROCR haplotypes, PROCR mRNA, cellular distribution of EPCR, and rate of PC activation. Finally, the functionality of the intragenic PROCR H1 single-nucleotide polymorphisms was analyzed using a luciferase-based method. We confirmed that individuals carrying H1 have reduced VTE risk, increased plasma activated PC levels, and reduced plasma sEPCR levels and that individuals with the H3H3 genotype have an increased VTE risk and increased plasma sEPCR levels. In cultured human umbilical vein endothelial cells, H1 is associated with increased membrane-bound EPCR, increased rate of PC activation, and reduced sEPCR in conditioned medium, but does not significantly influence PROCR mRNA levels. In contrast, H3 is associated with reduced membrane-bound EPCR and increased sEPCR in human umbilical vein endothelial cell–conditioned medium, higher levels of a truncated mRNA isoform, and a lower rate of PC activation. Finally, we identified the g.2132T>C single-nucleotide polymorphism in intron 1 as an intragenic H1-specific functional single-nucleotide polymorphism.

Conclusions—

These results support a protective role of PROCR H1 against VTE and an increased risk of VTE associated with the H3 haplotype.

Association of the Thrombomodulin Gene c.1418C>T Polymorphism With Thrombomodulin Levels and With Venous Thrombosis Risk

Objective—

To investigate the association of the THBD c.1418C>T polymorphism, which encodes for the replacement of Ala455 by Val in thrombomodulin (TM), with venous thromboembolism (VTE), plasma soluble TM, and activated protein C levels. In addition, human umbilical vein endothelial cells (HUVEC) isolated from 100 umbilical cords were used to analyze the relation between this polymorphism and THBD mRNA and TM protein expression.

Approach and Results—

The THBD c.1418C>T polymorphism was genotyped in 1173 patients with VTE and 1262 control subjects. Levels of soluble TM and activated protein C were measured in 414 patients with VTE (not on oral anticoagulants) and 451 controls. HUVECs were genotyped for the polymorphism and analyzed for THBD mRNA and TM protein expression and for the ability to enhance protein C activation by thrombin. The 1418T allele frequency was lower in patients than in controls ( P <0.001), and its presence was associated with a reduced VTE risk, reduced soluble TM levels, and increased circulating activated protein C levels ( P <0.001). In cultured HUVEC, the 1418T allele did not influence THBD expression but was associated with increased TM in cell lysates, increased rate of protein C activation, and reduced soluble TM levels in conditioned medium.

Conclusions—

The THBD 1418T allele is associated with lower soluble TM, both in plasma and in HUVEC-conditioned medium, and with an increase in functional membrane–bound TM in HUVEC, which could explain the increased activated protein C levels and the reduced VTE risk observed in individuals carrying this allele.

Peritoneal fluid reduces angiogenesis-related microRNA expression in cell cultures of endometrial and endometriotic tissues from women with endometriosis

Endometriosis, defined as the presence of endometrium outside the uterus, is one of the most frequent gynecological diseases. It has been suggested that modifications of both endometrial and peritoneal factors could be implicated in this disease. Endometriosis is a multifactorial disease in which angiogenesis and proteolysis are dysregulated. MicroRNAs (miRNAs) are small non-coding RNAs that regulate the protein expression and may be the main regulators of angiogenesis. Our hypothesis is that peritoneal fluid from women with endometriosis could modify the expression of several miRNAs that regulate angiogenesis and proteolysis in the endometriosis development. The objective of this study has been to evaluate the influence of endometriotic peritoneal fluid on the expression of six miRNAs related to angiogenesis, as well as several angiogenic and proteolytic factors in endometrial and endometriotic cell cultures from women with endometriosis compared with women without endometriosis.

Antithrombin Cambridge II (A384S) supports a role for antithrombin deficiency in arterial thrombosis

Although the control of thrombin in the microvasculature at the endothelial cell surface is crucial to prevent atherothrombosis, the role of antithrombin in arterial thrombosis is unclear. It is widely considered that antithrombin deficiency is unlikely to contribute to arterial thrombosis, but no convincing epidemiological study has been performed because of the low frequency of this deficiency. In this study we evaluated the role in myocardial infarction (MI) of a relatively common mutation affecting antithrombin gene (A384S: Antithrombin Cambridge II) that has functional features that may impair the right control of thrombogenic events caused by injury to the vascular wall. Moreover, this deficiency, which is not detected using common methods to diagnose antithrombin deficiency, also increases the risk of venous thrombosis. We included 1,224 patients with MI (691 consecutive patients and 533 survivors of a premature event), and 1,649 controls. The mutation was identified in 0.3% of controls, but 0.8% of MI patients. After adjusting for sex and other cardiovascular risk factors, the antithrombin Cambridge II significantly increased 5.66-fold the risk of MI (95% CI: 1.53-20.88; p = 0.009). Interestingly, young patients had the highest risk of MI associated with the mutation (OR: 9.98; 95%CI: 1.60-62.24; p = 0.009). This is the first epidemiological study that supports a role for antithrombin deficiency in arterial thrombosis. These results suggest that deficiency of antithrombin may be an independent risk factor for MI that has been underestimated, but larger studies are needed to confirm the relevance of inhibitors of thrombin in arterial thrombosis.

Insights into the role of microRNAs in cardiac diseases: from biological signalling to therapeutic targets

microRNAs have recently opened new pathways to explain gene expression and disease biology in many scenarios, including cardiac diseases. microRNAs are endogenous small non-coding RNAs that mediate post-transcriptional repression or messenger RNA degradation. By annealing to inexactly complementary sequences in the 3' untranslated region of the target messenger RNA, protein level is down-regulated. Several microRNAs appear to act cooperatively through multiple target sites in one gene and, conversely, most microRNAs can target several genes. miR-133 and miR-1 are specifically expressed in cardiac and skeletal muscle and control myogenesis, cardiac development, cardiac performance and cardiomyocyte hypertrophy (mainly by tuning transcription factors and other growth-related targets). They also modulate the expression of certain cardiac ion channels and related proteins with proarrhythmic effect. Besides them, other microRNAs have been shown to exert influence on the myocardial growth, the electrical balance and the angiogenesis processes that take place in the heart. Bioinformatics is a useful tool to identify potential targets of a given microRNA, although there is still substantial concern about their reliability. Experimental manipulation of microRNAs has provided a tantalizing basis to speculate that future research on microRNAs may yield important progress in the prevention of sudden cardiac death and in the treatment of cardiac heart failure. However, the final effect of the blockage of microRNAs in vivo remains unclear, since each of them can target hundreds of genes with different intensity. The era of the microRNAs in cardiovascular diseases has just started.

Activated protein C levels in obesity and weight loss influence

Obesity is associated with a high risk of cardiovascular events. Several haemostatic disturbances which could contribute to this increased risk have been described in obesity; nevertheless, the state of coagulation inhibitors has been scarcely studied in these patients. The aim of the present study was to compare activated protein C levels in obese patients and in a control group, and to evaluate the effect of weight loss. In 67 severe or morbid obese patients, an evaluation was performed at baseline and 3 months after diet. The same determinations were performed in 67 healthy volunteers with normal body weight. We also quantified the levels of protein C and prothrombin fragment 1+2. Obese patients showed significantly higher levels of activated protein C, protein C and fragment 1+2. No correlation was found between activated protein C and fragment 1+2 levels in obese patients. After three months of diet, a significant decrease in activated protein C and fragment 1+2 was observed. In conclusion, activated protein C levels are increased in obese patients, but only a minor fraction of this increase may be explained by the higher thrombin generation and C protein levels. Activated protein C levels decrease with weight loss, due in part to a thrombin generation reduction.