Specific Features of TLR4 Expression in Structural Elements of Placenta in Patients with Preeclampsia

The impact of hyperandrogenemia on pregnancy complications and outcomes in patients with PCOS: a systematic review and meta-analysis

BACKGROUND

Polycystic ovary syndrome (PCOS) is a metabolic and reproductive disorder. Current research findings present conflicting views on the effects of different PCOS phenotypes on outcomes in pregnancy and for newborns.

METHODS

This research study followed the guidelines of the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA). A thorough search of literature was carried out using the Cochrane Menstrual Disorders and Subfertility Group trials register, Web of Science, and EMBASE databases from their start to December 2023. The search focused on studies examining the links between hyperandrogenic and non-hyperandrogenic PCOS phenotypes and risks in pregnancy and neonatology. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed using either a fixed-effects or random-effects model.

RESULTS

Our analysis incorporated 10 research studies. Expectant mothers with a hyperandrogenic PCOS subtype had increased ORs for gestational diabetes mellitus (GDM) and preeclampsia (PE) compared to those with a non-hyperandrogenic PCOS subtype, with respective values of 2.14 (95% CI, 1.18-3.88, I2 = 0%) and 2.04 (95% CI, 1.02-4.08, I2 = 53%). Nevertheless, no notable differences were detected in ORs for outcomes like preterm birth, live birth, miscarriage, cesarean delivery, pregnancy-induced hypertension, small for gestational age babies, large for gestational age newborns, and neonatal intensive care unit admissions between pregnant women with hyperandrogenic PCOS phenotype and those without.

CONCLUSIONS

This meta-analysis highlights that the presence of hyperandrogenism heightens the risks of GDM and PE within the PCOS population. Healthcare providers ought to be aware of this connection for improved patient management.

Roles of human trophoblasts' pattern recognition receptors in host defense and pregnancy complications

The immune system in pregnancy is able to protect pregnant mothers and fetuses from pathogenic microorganisms even while permitting the mother to tolerate the semi-allogenic fetus. Trophoblasts, which are fetal-derived placental cells, play a central role on both sides of this duality at the maternal-fetal interface. In brief, the trophoblasts express pattern recognition receptors (PRRs) and are involved in the local innate immune response in the placenta. That response eliminates pathogenic microbes but also causes tissue damage. In this review, we summarize the research findings to date regarding the roles of those human trophoblast PRRs. Multiple types of PRRs (Toll-like receptors, Nod-like receptors, and RIG-I-like receptors) are expressed in the placenta and on trophoblasts. Trophoblasts' PRRs participate in protecting the fetus against viruses, bacteria, and parasites by triggering production of proinflammatory cytokines and chemokines in the placenta. On the negative side, PRR signaling in trophoblasts can also initiate inflammation and trophoblast cell death, which can lead to placental inflammation-associated pregnancy complications such as preeclampsia, anti-phospholipid antibody syndrome, and miscarriage. Further elucidation of these dual roles of trophoblasts' PRRs may shed light on the mechanisms by which fetuses are protected against congenital infections and also give us a better understanding of the etiologies of pregnancy complications, which can help us prevent/reduce adverse prenatal/neonatal outcomes.

Preeclampsia and Obesity-The Preventive Role of Exercise

Obesity is now recognized as a worldwide epidemic. An inadequate diet and reduced physical activity are acknowledged as the leading causes of excess body weight. Despite growing evidence that obesity is a risk factor for unsuccessful pregnancies, almost half of all women who become pregnant today are overweight or obese. Common complications of pregnancy in this group of women are preeclampsia and gestational hypertension. These conditions are also observed more frequently in women with excessive weight gain during pregnancy. Preeclampsia is one of the most serious pregnancy complications with an unpredictable course, which in its most severe forms, threatens the life and health of the mother and her baby. The early identification of the risk factors for preeclampsia development, including obesity, allows for the implementation of prophylaxis and a reduction in maternal and fetal complications risk. Additionally, preeclampsia and obesity are the recognized risk factors for developing cardiovascular disease in later life, so prophylaxis and treating obesity are paramount for their prevention. Thus, a proper diet and physical activity might play an essential role in the prophylaxis of preeclampsia in this group of women. Limiting weight gain during pregnancy and modifying the metabolic risk factors with regular physical exercise creates favorable metabolic conditions for pregnancy development and benefits the elements of the pathogenetic sequence for preeclampsia development. In addition, it is inexpensive, readily available and, in the absence of contraindications to its performance, safe for the mother and fetus. However, for this form of prevention to be effective, it should be applied early in pregnancy and, for overweight and obese women, proposed as an essential part of planning pregnancy. This paper aims to present the mechanisms of the development of hypertension in pregnancy in obese women and the importance of exercise in its prevention.

The Placental Innate Immune System Is Altered in Early-Onset Preeclampsia, but Not in Late-Onset Preeclampsia

Preeclampsia is a severe placenta-related pregnancy disorder that is generally divided into two subtypes named early-onset preeclampsia (onset <34 weeks of gestation), and late-onset preeclampsia (onset ≥34 weeks of gestation), with distinct pathophysiological origins. Both forms of preeclampsia have been associated with maternal systemic inflammation. However, alterations in the placental immune system have been less well characterized. Here, we studied immunological alterations in early- and late-onset preeclampsia placentas using a targeted expression profile approach. RNA was extracted from snap-frozen placenta samples (healthy n=13, early-onset preeclampsia n=13, and late-onset preeclampsia n=6). The expression of 730 immune-related genes from the Pan Cancer Immune Profiling Panel was measured, and the data were analyzed in the advanced analysis module of nSolver software (NanoString Technology). The results showed that early-onset preeclampsia placentas displayed reduced expression of complement, and toll-like receptor (TLR) associated genes, specifically TLR1 and TLR4. Mast cells and M2 macrophages were also decreased in early-onset preeclampsia compared to healthy placentas. The findings were confirmed by an immunohistochemistry approach using 20 healthy, 19 early-onset preeclampsia, and 10 late-onset preeclampsia placentas. We conclude that the placental innate immune system is altered in early-onset preeclampsia compared to uncomplicated pregnancies. The absence of these alterations in late-onset preeclampsia placentas indicates dissimilar immunological profiles. The study revealed distinct pathophysiological processes in early-onset and late-onset preeclampsia placentas and imply that a tailored treatment to each subtype is desirable.

TLR4-Endothelin Axis Controls Syncytiotrophoblast Motility and Confers Fetal Protection in Placental Malaria

Pregnancy-associated malaria is often associated with adverse pregnancy outcomes. Placental circulatory impairments are an intriguing and unsolved component of malaria pathophysiology. Here, we uncovered a Toll-like receptor 4 (TLR4)-TRIF-endothelin axis that controls trophoblast motility and is linked to fetal protection during Plasmodium infection. In a cohort of 401 pregnancies from northern Brazil, we found that infection during pregnancy reduced expression of endothelin receptor B in syncytiotrophoblasts, while endothelin expression was only affected during acute infection. We further show that quantitative expression of placental endothelin and endothelin receptor B proteins are differentially controlled by maternal and fetal TLR4 alleles. Using murine malaria models, we identified placental autonomous responses to malaria infection mediated by fetally encoded TLR4 that not only controlled placental endothelin gene expression but also correlated with fetal viability protection. In vitro assays showed that control of endothelin expression in fetal syncytiotrophoblasts exposed to Plasmodium-infected erythrocytes was dependent on TLR4 via the TRIF pathway but not MyD88 signaling. Time-lapse microscopy in syncytiotrophoblast primary cultures and cell invasion assays demonstrated that ablation of TLR4 or endothelin receptor blockade abrogates trophoblast collective motility and cell migration responses to infected erythrocytes. These results cohesively substantiate the hypothesis that fetal innate immune sensing, namely, the TRL4-TRIF pathway, exerts a fetal protective role during malaria infection by mediating syncytiotrophoblast vasoregulatory responses that counteract placental insufficiency.

A promising novel biomarker for early-onset preeclampsia: soluble trigger receptor expressed on myeloid cells-1 (sTREM-1)

BACKGROUND

We aimed to explore TREM-1 activation in pregnant women who has preeclampsia through the measurement of its soluble form sTREM.

METHODS

A prospective cohort study was conducted. Participants were recruited from antenatal clinic between 1 May 2019 and 31 August 2019, and they all provided written informed consent for participation. Women between 18 and 42 years of age who were diagnosed with early or late-onset preeclampsia (LOP) were offered participation if they did not have any known systemic disease (chronic hypertension, diabetes, hypothyroidism, chronic renal-liver diseases, etc.); autoimmune disorders; multiple pregnancies; presence of fetal structural and chromosomal anomalies; placenta previa; cholestasis of pregnancy; preterm delivery; evidence of chronic and active infection. The primary outcome of the study was to assess any difference between groups in terms of the diagnostic value of sTREM level.

RESULTS

A total of 80 patients were enrolled; proven early-onset preeclampsia (EOP) (n = 20), LOP (n = 30), and control (n = 30) groups. There was no significant difference among the groups in terms of age and BMI. Mean gestational age at diagnosis of EOP; 30 ± 1.9 and LOP; 34.7 ± 1.9 weeks gestation. The mean sTREM level was 160.130 ± 1.65 pg/ml in the EOP group, 119.337 ± 2.04 pg/ml in LOP group, and 87.764 ± 1.69 pg/ml in the control group. According to subgroup analysis, sTREM levels were significantly higher in EOP group than control group.

CONCLUSIONS

sTREM might be a promising biomarker for early detection of EOP. However, future studies are necessary to confirm this hypothesis.

The relationship among vitamin D, TLR4 pathway and preeclampsia

Preeclampsia is a pregnancy-specific syndrome that has been the greatest cause of maternal and fetal morbidity and mortality. The impaired outcomes are related to maternal and the offspring healthy in the short and long-term. Although preeclampsia origins remain unclear, it is well known that there is impaired trophoblast invasion with culminant abnormal immune response. The early and late-onset preeclampsia have been studied, the subtypes have the same difference in the placentation and inflammatory features. Dietary compounds can stimulate or inhibit the activation of immune cells. Low vitamin D intake has been linked to impaired fetal development, intrauterine growth restriction, and preeclampsia. Vitamin D has been described as an anti-inflammatory effect. It can downregulate pro-inflammatory cytokines expression by the inhibition of the Nuclear Factor-ĸB pathway signaling cascade. High vitamin D levels could attenuate the immune response. On the other hand, vitamin D deficiency may contribute to increasing pro-inflammatory state. In preeclampsia, there is a reduced expression of vitamin D receptor and its metabolism is disrupted. In this review, we aimed to discuss the role of vitamin D as an anti-inflammatory agent in relation to the pro-inflammatory process of preeclampsia through the activation of the TLR4 pathway. Although there are limited studies showing the relation between vitamin D and lower risk of preeclampsia, the maternal status of vitamin D seems to influence the risk of PE development. Therefore, vitamin D supplementation in women may be a strategy to improve pregnancy outcomes.

Maternal-Fetal Conflict During Infection: Lessons From a Mouse Model of Placental Malaria

Infections that reach the placenta via maternal blood can target the fetal-placental barrier and are associated with reduced birth weight, increased stillbirth, miscarriage and perinatal mortality. Malaria during pregnancy can lead to infection of the placental tissue and to adverse effects on the unborn child even if the parasite is successfully cleared, indicating that placental sufficiency is significantly compromised. Human samples and animal models of placental malaria have been used to unravel mechanisms contributing to this insufficiency and have implicated molecular pathways related to inflammation, innate immunity and nutrient transport. Remarkably, fetal TLR4 was found to take part in placental responses that protect the fetus, in contrast to maternal TLR4 responses that presumably preserve the mother‘s health but result in reduced fetal viability. We propose that this conflict of fetal and maternal responses is a determinant of the clinical outcomes of placental malaria and that fetally derived trophoblasts are on the front lines of this conflict.

Increased serum levels of high mobility group protein B1 and calprotectin in pre-eclampsia

OBJECTIVE

To determine whether women with pre-eclampsia have serum levels of biomarkers indicative of an elevated systemic inflammatory response.

METHOD

The present cross-sectional study was conducted among pregnant women either with pre-eclampsia or without pre-eclampsia who were recruited at a single Chinese hospital between August 1, 2016, and April 30, 2017. Eligible women had no history of acute or chronic inflammation. Serum concentrations of high mobility group protein B1 (HMG-1), calprotectin, and Toll-like receptor 4 (TLR4) were measured and compared.

RESULTS

There were 55 patients included (25 with pre-eclampsia and 30 without). The mean serum concentration of calprotectin was 2656.76 ± 1724.56 μg/L in the pre-eclampsia group versus 1877.33 ± 905.69 μg/L in the control group (P=0.036). Among patients with pre-eclampsia, elevated calprotectin levels were positively associated with the duration of hypertension in pregnancy (P=0.031) and were negatively associated with pregnancy duration at delivery (P=0.035). The mean serum concentration of HMG-1 was 72.48 ± 27.57 μg/L in the pre-eclampsia group versus 57.57 ± 20.07 μg/L in the control group (P=0.017). The mean serum concentration of TLR4 was 22.83 ± 8.46 μg/L in the pre-eclampsia group versus 18.83 ± 6.79 μg/L in the control group (P=0.057).

CONCLUSION

Elevated levels of HMG-1 and calprotectin could reflect an excessive systemic inflammatory response in pre-eclampsia.

Immunological Tolerance, Pregnancy, and Preeclampsia: The Roles of Semen Microbes and the Father

Although it is widely considered, in many cases, to involve two separable stages (poor placentation followed by oxidative stress/inflammation), the precise originating causes of preeclampsia (PE) remain elusive. We have previously brought together some of the considerable evidence that a (dormant) microbial component is commonly a significant part of its etiology. However, apart from recognizing, consistent with this view, that the many inflammatory markers of PE are also increased in infection, we had little to say about immunity, whether innate or adaptive. In addition, we focused on the gut, oral and female urinary tract microbiomes as the main sources of the infection. We here marshall further evidence for an infectious component in PE, focusing on the immunological tolerance characteristic of pregnancy, and the well-established fact that increased exposure to the father's semen assists this immunological tolerance. As well as these benefits, however, semen is not sterile, microbial tolerance mechanisms may exist, and we also review the evidence that semen may be responsible for inoculating the developing conceptus (and maybe the placenta) with microbes, not all of which are benign. It is suggested that when they are not, this may be a significant cause of PE. A variety of epidemiological and other evidence is entirely consistent with this, not least correlations between semen infection, infertility and PE. Our view also leads to a series of other, testable predictions. Overall, we argue for a significant paternal role in the development of PE through microbial infection of the mother via insemination.

DAI-1 Receptor Expression in Placenta in Earlyand Late-Onset Preeclampsia

DAI-1 receptor (DNA-dependent activator of IFN-regulatory factors; DLM-1/ZBP-1) is an innate immunity cytoplasmic receptor of the DNA-recognition receptor class of antiviral immunity. DAI-1 expression reflects the severity of the inflammatory response that plays the key role in the pathogenesis of pregnancy complications. We studied DAI-1 receptor expression in the placental villi in early- and late-onset preeclampsia. In case of early-onset preeclampsia DAI-1 staining intensity was lower (p=0.01), and in case of late preeclampsia - significantly higher (p<0.005) than in the reference groups at the corresponding gestational age. There was revealed a correlation between the decrease in DAI-1 receptor expression and the severity of disease progression.

Expression of MicroRNA-146a and MicroRNA-155 in Placental Villi in Early- and Late-Onset Preeclampsia

We studied the expression of microRNA-146a and microRNA-155 in placental villi from 18 women (26-39 weeks of gestation) of reproductive age with early- or late-onset preeclampsia. The reference group consisted of women with physiological pregnancy and full-term gestation and with preterm birth after caesarian section on gestation week 26-31. MicroRNA-146a and microRNA-155 were detected by in situ hybridization with digoxigenin on paraffin sections. It was found that the expression of microRNA-146a in both syncytiotrophoblast of the intermediate villi and syncytial knots was lower at late-onset preeclampsia than at physiologic pregnancy of full-term period (p=0.037 and p=0.001 respectively). The expression of microRNA-155 in syncytiotrophoblast of intermediate placental villi in early-onset preeclampsia was higher than in group with preterm delivery (p=0.003). However, in syncytiotrophoblast of intermediate villi and in syncytial knots, the expression of microRNA-155 was lower at late-onset preeclampsia in comparison with full-term physiological pregnancy (p=0.005). In addition, the expression of microRNA-146a and microRNA-155 did not increase in the later terms in preeclampsia, while in the reference groups demonstrating gradual increase in the expression of these markers with increasing gestational age. Expression microRNA-146a and microRNA-155 little differed in early- and late-onset preeclampsia. These findings suggest that different variants of preeclampsia are probably characterized by common pathogenetic pathways. Damaged trophoblast cannot maintain of microRNAs synthesis at the required level, which determines the formation of a vicious circle in preeclampsia and further progression of the disease.