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Unexplained recurrent pregnancy loss (uRPL) is a clinical condition for which there is a lack of evidenced-based therapies. However, in clinical practice, low molecular weight heparin (LMWH) has been widely used as an empirical therapy since immune effects have been hypothesized in modulating immune tolerance at the fetal maternal interface. Epigenetic mechanisms are involved in establishing of immune tolerance, at fetal-maternal interface. To investigate potential induced immune-epigenetic changes at maternal periphery level, which could reflect the maternal-fetal interface condition, seems to open up new therapeutical strategies, since microRNAs circulating in maternal plasma and in peripheral blood mononuclear cells (PBMCs) may be specific and sensitive immunological markers/predictors of adverse pregnancy outcomes such as RPL.Our aim in this pilot study is to evaluate potential LMWH effects on genes regulating immunological response key mechanisms related to maternal-fetal tolerance processes, by studying circulating miRNAs in maternal peripheral blood. We tested a panel of selected miRNAs on three groups: 18 healthy pregnant women, 20 pregnant women affected by uRPL, 18 pregnant women affected by uRPL, treated with LMWH. The majority of differentially expressed miRNAs (miR 374a-5p, 19a-3p, 30e-5p, 128-3p, 155-5p and 200c-3p) were found to be modulated by LMWH, which seems to have a positive function in RPL patients, by bringing patients values back to those comparable to the control ones. Selected microRNA panels would appear to be an effective clinical tool for uRPL diagnosis and management. LMWH-modified miRNA expression levels could be targets for immunotherapy, as LMWH would appear to restore physiological miRNA levels, which are dysregulated in uRPL., Funding Agencies|Research Project "Mission: Sustainability" [2817]; Tor Vergata University. "IKiRM -Inflammatory and oxidant trophoblastic factors expression in unexplained Recurrent Miscarriages" [E81I18000430001]

Decidualization is characterized by a series of genetic, metabolic, morphological, biochemical, vascular and immune changes occurring in the endometrial stroma in response to the implanting embryo or even before conception and involves the stromal cells of the endometrium. It is a fundamental reproductive event occurring in mammalian species with hemochorial placentation. A growing body of experimental and clinical evidence strongly suggests that defective or disrupted decidualization contributes to the establishment of an inappropriate maternal-fetal interface. This has relevant clinical consequences, ranging from recurrent implantation failure and recurrent pregnancy loss in early pregnancy to several significant complications of advanced gestation. Moreover, recent evidence indicates that selected diseases of the endometrium, such as chronic endometritis and endometriosis, can have a detrimental impact on the decidualization response in the endometrium and may help explain some aspects of the reduced reproductive outcome associated with these conditions. Further research efforts are needed to fully understand the biomolecular mechanisms ans events underlying an abnormal decidualization response. This will permit the development of new diagnostic and therapeutic strategies aimed to improve the likelihood of achieveing a successful pregnancy.

In the present manuscript, we review the recent research investigating the pathogenic association between most studied autoantibodies and recurrent pregnancy loss. Pregnancy loss represents a common obstetric complication occurring in about 15%-25% of all clinically recognized pregnancies. The recurrence of pregnancy loss identifies a distinct clinical entity, that is recurrent pregnancy loss (RPL), affecting about 2%-4% of couples. Several factors, including age, chromosomal abnormalities, uterine anomalies, thrombophilic disorders, endocrinopathies, hormonal and metabolic disorders, infections, sperm quality, and lifestyle issues, are involved in RPL. The role of autoantibodies in RPL is only partially determined. In some cases (antiphospholipid antibodies [aPL]), their involvement is well established. In other cases (anti-thyroid autoantibodies, antinuclear, anti-transglutaminase, and anti-endomysial antibodies), it is still debated, despite multiple, although not fully conclusive, evidences strongly suggest a possible involvement in RPL. Further extensive research is needed to definitively confirm or exclude their actual role.

The aim of this prospective cohort study was to determine whether women with recurrent pregnancy loss (RPL) have an increased risk of pregnancy complications compared to normal pregnant women. A total of 1092 singleton pregnancies were followed, 431 in women with RPL and 661 in normal healthy women. The prevalence of the following complications was observed: threatened miscarriage, miscarriage, cervical insuciency, chromosomal/genetic abnormalities, fetal anomalies, oligohydramnios, polyhydramnios, fetal growth restriction, intrauterine fetal death, gestational diabetes mellitus (GDM), preeclampsia, placenta previa, abruptio placentae, pregnancy-related liver disorders, and preterm premature rupture of the membranes. The odds ratio and 95% CI for each pregnancy complication considered were determined by comparing women with RPL and normal healthy women. Women with RPL had an overall rate of pregnancy complications higher than normal women (OR = 4.37; 95% CI: 3.353–5.714; p < 0.0001). Their risk was increased for nearly all the conditions considered. They also had an increased risk of multiple concomitant pregnancy complications (OR = 4.64; 95% CI: 3.10–6.94, p < 0.0001). Considering only women with RPL, women with 3 losses had a higher risk of pregnancy complications than women with two losses (OR = 1.269; 95% CI: 1.112–2.386, p < 0.02). No dierences were found in the overall risk of pregnancy complications according to the type, explained or unexplained, of RPL. Women with secondary RPL had an increased risk of GDM than women with primary RPL. Pregnancy in women with RPL should be considered at high risk.

To determine whether differences are present in the time-to-pregnancy (TTP) between women with unexplained recurrent pregnancy loss (uRPL) and control women, in this case-control, retrospective study, carried out in tertiary university hospitals, the TTP, defined as the months needed to reach pregnancy from when the woman started to try to conceive, was determined in 512 women, 207 of which were diagnosed as having uRPL and 305 were normal healthy control women. The specific TTPs for each pregnancy, stratified by order of pregnancy occurrence, were also determined. Pregnancy rates by time were calculated by using the Kaplan-Meier method to construct the survival curves. The age at which the pregnancies occurred was determined. Comparisons were carried out between women with uRPL and controls. Overall, 1192 pregnancies occurred and were analyzed. Mean TTP in uRPL women was shorter than in controls (P < 0.001) when all the pregnancies were considered. Similarly, it was shorter in the first, second, third, and fifth pregnancy. The pregnancy rates of uRPL women were shorter than that of control women for the first three pregnancies, for which the numbers of subjects allowed the comparisons to be made. These findings were observed despite maternal age of uRPL women was higher than that of control women. TTP is shorter in uRPL than in normal women. This finding clinically supports to the hypothesis that women with uRPL could be, at least in early stages of pregnancy, more fertile or receptive toward the implanting embryo than healthy women.

Recurrent pregnancy loss (RPL) represents an unresolved problem for contemporary gynecology and obstetrics. In fact, it is not only a relevant complication of pregnancy, but is also a significant reproductive disorder affecting around 5% of couples desiring a child. The current knowledge on RPL is largely incomplete, since nearly 50% of RPL cases are still classified as unexplained. Emerging evidence indicates that the endometrium is a key tissue involved in the correct immunologic dialogue between the mother and the conceptus, which is a condition essential for the proper establishment and maintenance of a successful pregnancy. The immunologic events occurring at the maternal-fetal interface within the endometrium in early pregnancy are extremely complex and involve a large array of immune cells and molecules with immunoregulatory properties. A growing body of experimental studies suggests that endometrial immune dysregulation could be responsible for several, if not many, cases of RPL of unknown origin. The present article reviews the major immunologic pathways, cells, and molecular determinants involved in the endometrial dysfunction observed with specific application to RPL.