Decreased IL-33 Production Contributes to Trophoblast Cell Dysfunction in Pregnancies with Preeclampsia

IL-33 Signaling Inhibition Leads to a Preeclampsia-Like Phenotype in Pregnant Rats

PROBLEM

Preeclampsia (PE) is a hypertensive pregnancy disorder that is a leading cause of maternal and fetal morbidity and mortality characterized by maternal vascular dysfunction, oxidative stress, chronic immune activation, and excessive inflammation. No cure exists beyond delivery of the fetal-placental unit and the mechanisms driving pathophysiology are not fully understood. However, aberrant immune responses have been extensively characterized in clinical studies and shown to mediate PE pathophysiology in animal studies. One pathway that may mediate aberrant immune responses in PE is deficiencies in the IL-33 signaling pathway. In this study, we aim to investigate the impact of IL-33 signaling inhibition on cNK, TH17, and TReg populations, vascular function, and maternal blood pressure during pregnancy.

METHOD OF STUDY

In this study, IL-33 signaling was inhibited using two different methods: intraperitoneal administration of recombinant ST2 (which acts as a decoy receptor for IL-33) and administration of a specific IL-33 neutralizing antibody. Maternal blood pressure, uterine artery resistance index, renal and placental oxidative stress, cNK, TH17, and TReg populations, various cytokines, and pre-proendothelin-1 levels were measured.

RESULTS

IL-33 signaling inhibition increased maternal blood pressure, uterine artery resistance, placental and renal oxidative stress. IL-33 signaling inhibition also increased placental cNK and TH17 and renal TH17 cells while decreasing placental TReg populations. IL-33 neutralization increased circulating cNK and TH17s and decreased circulating TRegs in addition to increasing pre-proendothelin-1 levels.

CONCLUSIONS

Data presented in this study demonstrate a role for IL-33 signaling in controlling vascular function and maternal blood pressure during pregnancy possibly by mediating innate and adaptive immune inflammatory responses, identifying the IL-33 signaling pathway as a potential therapeutic target for managing preeclampsia.

IL-33 supplementation improves uterine artery resistance and maternal hypertension in response to placental ischemia

Preeclampsia (PE), a leading cause of maternal/fetal morbidity and mortality, is a hypertensive pregnancy disorder with end-organ damage that manifests after 20 wk of gestation. PE is characterized by chronic immune activation and endothelial dysfunction. Clinical studies report reduced IL-33 signaling in PE. We use the Reduced Uterine Perfusion Pressure (RUPP) rat model, which mimics many PE characteristics including reduced IL-33, to identify mechanisms mediating PE pathophysiology. We hypothesized that IL-33 supplementation would improve blood pressure (BP), inflammation, and oxidative stress (ROS) during placental ischemia. We implanted intraperitoneal mini-osmotic pumps infusing recombinant rat IL-33 (1 µg/kg/day) into normal pregnant (NP) and RUPP rats from gestation day 14 to 19. We found that IL-33 supplementation in RUPP rats reduces maternal blood pressure and improves the uterine artery resistance index (UARI). In addition to physiological improvements, we found decreased circulating and placental cytolytic Natural Killer cells (cNKs) and decreased circulating, placental, and renal TH17s in IL-33-treated RUPP rats. cNK cell cytotoxic activity also decreased in IL-33-supplemented RUPP rats. Furthermore, renal ROS and placental preproendothelin-1 (PPET-1) decreased in RUPP rats treated with IL-33. These findings demonstrate a role for IL-33 in controlling vascular function and maternal BP during pregnancy by decreasing inflammation, renal ROS, and PPET-1 expression. These data suggest that IL-33 may have therapeutic potential in managing PE.NEW & NOTEWORTHY Though decreased IL-33 signaling has been clinically associated with PE, the mechanisms linking this signaling pathway to overall disease pathophysiology are not well understood. This study provides compelling evidence that mechanistically links reduced IL-33 with the inflammatory response and vascular dysfunction observed in response to placental ischemia, such as in PE. Data presented in this study submit the IL-33 signaling pathway as a possible therapeutic target for the treatment of PE.

DHT and Insulin Upregulate Secretion of the Soluble Decoy Receptor of IL-33 From Decidualized Endometrial Stromal Cells

Interleukin 33 (IL-33) signaling regulates most of the key processes of pregnancy, including decidualization, trophoblast proliferation and invasion, vascular remodeling, and placental growth. Accordingly, dysregulation of IL-33, its membrane-bound receptor (ST2L, transducer of IL-33 signaling), and its soluble decoy receptor (sST2, inhibitor of IL-33 signaling) has been linked to a wide range of adverse pregnancy outcomes that are common in women with obesity and polycystic ovary syndrome, that is, conditions associated with hyperandrogenism, insulin resistance, and compensatory hyperinsulinemia. To reveal if androgens and insulin might modulate uteroplacental IL-33 signaling, we investigated the effect of dihydrotestosterone (DHT) and/or insulin on the expression of ST2L and sST2 (along with the activity of their promoter regions), IL-33 and sIL1RAP (heterodimerization partner of sST2), during in vitro decidualization of endometrial stromal cells from 9 healthy women. DHT and insulin markedly upregulated sST2 secretion, in addition to the upregulation of its messenger RNA (mRNA) expression, while the proximal ST2 promoter, from which the sST2 transcript originates, was upregulated by insulin, and in a synergistic manner by DHT and insulin combination treatment. On the other hand, sIL1RAP was slightly downregulated by insulin and IL-33 mRNA expression was not affected by any of the hormones, while ST2L mRNA expression and transcription from its promoter region (distal ST2 promoter) could not be detected or showed a negligibly low level. We hypothesize that high levels of androgens and insulin might lead to subfertility and pregnancy complications, at least partially, through the sST2-dependent downregulation of uteroplacental IL-33 signaling.

Downregulation of TCL6 protected human trophoblast cells from LPS-induced inflammation and ferroptosis

Dysregulation of noncoding RNAs has been reported to have a close correlation with preeclampsia(PE)development. TCL6 was upregulated in patients with PE. In this study, we examined the impacts of TCL6 on modulating HTR-8/SVneo cells induced by LPS. LPS (100 and 200 ng/ml) was applied to induce inflammation in trophoblast cells HTR-8/SVneo. Cell viability, apoptosis, and transwell experiments were conducted. The ELISA methods were used for pro-inflammatory cytokines IL-1β, IL-6, and TNF-α. MDA, GSH, and GPX kits were employed. Transfection was performed for expression regulation of TCL6, miR-485-5p, and TFRC in cells. Bioinformatic online tools were used to predict the targeting sites. Luciferase and RNA immunoprecipitation-qPCR were done to verify the interactions of TCL6, miR-485-5p, and TFRC. RNA expression levels were measured using RT-qPCR, and protein expression of TFRC and GPX4 was detected using a western blot. The free Fe (II) contents were measured. LPS decreased viability, invasion, and migration but enhanced apoptosis, ferroptosis, and inflammation. TCL6 expression was enhanced by LPS induction. The knockdown of TCL6 increased HTR-8/SVneo cell viability and invasion but inhibited cell apoptosis, inflammation, and ferroptosis while inhibition of miR-485-5p could reverse this through TFRC regulation. Moreover, miR-485-5p was sponged by TCL6 and bound to TFRC. TCL6 protected trophoblast cells from LPS-induced injury through the TFRC pathway.

Identification of novel candidate targets for suppressing ovarian cancer progression through IL-33/ST2 axis components using the system biology approach

Background: Cancer-associated fibroblasts (CAFs) of ovarian cancer (OvC) are the most prevalent element of the tumor microenvironment (TM). By promoting angiogenesis, immunological suppression, and invasion, CAFs speed up the growth of tumors by changing the extracellular matrix's structure and composition and/or initiating the epithelial cells (EPT). IL-33/ST2 signaling has drawn a lot of attention since it acts as a pro-tumor alarmin and encourages spread by altering TM. Methods: Differentially expressed genes (DEGs) of the OvC tumor microenvironment were found in the GEO database, qRT-PCR, western blotting, and immunohistochemistry, and their presence and changes in healthy and tumor tissue content were examined. Primary cultures of healthy fibroblasts and CAFs obtained from healthy and tumor tissues retrieved from OvC samples were used for in vitro and in vivo investigations. Cultured primary human CAFs were utilized to investigate the regulation and the IL-33/ST2 axis role in the inflammation reactions. Results: Although ST2 and IL-33 expression was detected in both epithelial (EPT) and fibroblast cells of ovarian cancer, they are more abundant in CAFs. Lipopolysaccharides, serum amyloid A1, and IL-1β, the inflammatory mediators, could all induce IL-33 expression through NF-κB activation in human CAFs. In turn, via the ST2 receptor, IL-33 affected the production of IL-6, IL-1β, and PTGS2 in human CAFs via the MAPKs-NF-κB pathway. Conclusion: Our findings suggest that IL-33/ST2 is affected by the interaction of CAFs and epithelial cells inside the tumor microenvironment. Activation of this axis leads to increased expression of inflammatory factors in tumor CAFs and EPT cells. Therefore, targeting the IL-33/ST2 axis could have potential value in the prevention of OvC progression.

NLRP3 inhibition improves maternal hypertension, inflammation, and vascular dysfunction in response to placental ischemia

Preeclampsia (PE) is a pregnancy-specific hypertensive disorder with end-organ damage that presents after 20 wk of gestation. PE pathophysiology often includes vascular dysfunction and increased inflammation that continues to damage patient health even after PE resolves. Currently, there is no cure for PE beyond delivery of the fetal-placental unit. Previous clinical studies have identified elevated placental NLRP3 expression in patients with PE and suggest NLRP3 as a potential therapeutic target. In this study, we examined the effect of NLRP3 inhibition on PE pathophysiology in the reduced uterine perfusion pressure (RUPP) model rat using MCC950 (20 mg/kg/day) or esomeprazole (3.5 mg/kg/day). We hypothesized that increased NLRP3 in response to placental ischemia impairs anti-inflammatory IL-33 signaling to induce T-helper 17 cell (TH17) and cytolytic NK cell (cNK) activation, which is known to mediate oxidative stress and vascular dysfunction leading to maternal HTN and intrauterine growth restriction. RUPP rats had significantly higher placental NLRP3 expression, maternal blood pressure, fetal reabsorption rate, vascular resistance, oxidative stress, cNKs and TH17s, and decreased IL-33 compared with normal pregnant (NP) rats. NLRP3 inhibition, with either treatment, significantly reduced placental NLRP3 expression, maternal blood pressure, fetal reabsorption rates, vascular resistance, oxidative stress, cNK, and TH17 populations in RUPP rats. Based on our findings, NLRP3 inhibition reduces PE pathophysiology and esomeprazole may be a potential therapeutic for PE treatment.

Tacrolimus improved the pregnancy outcomes of patients with refractory recurrent spontaneous abortion and immune bias disorders: a randomized controlled trial

OBJECTIVE

To investigate the effect of tacrolimus treatment on refractory recurrent spontaneous abortion (RSA) patients with elevated serum IL-33/ST2 levels.

METHODS

This study was a randomized controlled trial (RCT) of refractory RSA patients with elevated peripheral blood IL-33/ST2 levels or an elevated Th1/Th2 cell ratio. A total of 149 women were enrolled, each of whom had had at least 3 serial miscarriages and was confirmed to have elevated peripheral blood IL-33/ST2 levels or an elevated Th1/Th2 cell ratio. These women were randomly divided into two groups. The tacrolimus group (n = 75) received basic therapy with the addition of tacrolimus (Prograf). Tacrolimus was administered at a dose of 0.05 ~ 0.1 mg/kg/day from the end of the menstrual period to the beginning of the next menstrual period or to the 10th week of pregnancy. In contrast, basic therapy with the addition of placebo was given to the placebo group (n = 74). The main study outcome was the delivery of healthy newborns without deformities.

RESULTS

A total of 60 (80.00%) patients in the tacrolimus group and 47 (63.51%) patients in the placebo group delivered healthy newborns [P = 0.03, odds ratio = 2.30; 95% confidence interval (1.10 ~ 4.81)]. The peripheral blood IL-33/ST2 levels and Th1/Th2 cell ratio of the tacrolimus group were much lower than those of the placebo group (P < 0.05).

CONCLUSION

We validated our previous finding that serum IL-33 and sST2 concentrations are related to RSA. Immunosuppressive treatment with tacrolimus was demonstrated to be a promising method to treat refractory RSA with immune bias disorders.

The Reparative Roles of IL-33

When discovered in the early 2000s, interleukin-33 (IL-33) was characterized as a potent driver of type 2 immunity and implicated in parasite clearance, as well as asthma, allergy, and lung fibrosis. Yet research in other models has since revealed that IL-33 is a highly pleiotropic molecule with diverse functions. These activities are supported by elusive release mechanisms and diverse expression of the IL-33 receptor, STimulation 2 (ST2), on both immune and stromal cells. Interestingly, IL-33 also supports type 1 immune responses during viral and tumor immunity and after allogeneic hematopoietic stem cell transplantation. Yet the IL-33-ST2 axis is also critical to the establishment of systemic homeostasis and tissue repair and regeneration. Despite these recent findings, the mechanisms by which IL-33 governs the balance between immunity and homeostasis or can support both effective repair and pathogenic fibrosis are poorly understood. As such, ongoing research is trying to understand the potential reparative and regulatory versus pro-inflammatory and pro-fibrotic roles for IL-33 in transplantation. This review provides an overview of the emerging regenerative role of IL-33 in organ homeostasis and tissue repair as it relates to transplantation immunology. It also outlines the known impacts of IL-33 in commonly transplanted solid organs and covers the envisioned roles for IL-33 in ischemia-reperfusion injury, rejection, and tolerance. Finally, we give a comprehensive summary of its effects on different cell populations involved in these processes, including ST2 + regulatory T cells, innate lymphoid cell type 2, as well as significant myeloid cell populations.

The correlation between maternal serum sST2, IL-33 and NT-proBNP concentrations and occurrence of pre-eclampsia in twin pregnancies: A longitudinal study

The primary objective of this study was to determine the longitudinal profile of serum sST2 (soluble suppression of tumorigenicity 2), IL‐33 (interleukin‐33) and NT‐proBNP (N‐terminal pro‐brain natriuretic peptide) concentrations in twin pregnancies with pre‐eclampsia (PE) and those normotensive twins. The secondary objective was to test whether the change of serum sST2,IL‐33 and NT‐proBNP is related to PE in twin pregnancies. This is a longitudinal nested case–control study and all 156 dichorionic (DC) pregnancies were from a prospective cohort of twin pregnancies who received antenatal care and gave two live births at Peking University Third Hospital between October 2017 and September 2020. Four to five milliliters of peripheral blood of each pregnant woman were collected during the following three intervals: (1) 6–11⁺⁶ weeks; (2) 24–27⁺⁶ weeks; (3) 28–31⁺⁶ weeks. We found that sST2 and NT‐proBNP levels increased as pregnancy progressed in normotensive twin pregnancies and further increased in PE group, while no differences were found in IL‐33 levels throughout pregnancy. Then the correlation of biomarker levels with the occurrence of PE was assessed. Our results indicated that combining maternal serum sST2 and NT‐proBNP levels yielded the highest predictive value on the occurrence of PE significantly higher than the predictive value of any markers alone. Interestingly, the predictive value of second trimester (AUC = 0.876, 95%CI 0.824–0.928, LR−0.338, LR+7.67, p < 0.001)was higher than that of early‐third trimester (AUC = 0.832, 95%CI 0.769–0.896, LR−0.29, LR+3.845, p < 0.001). Serum sST2 and NT‐proBNP concentrations during second and early‐third trimester were associated with the occurrence of PE in twin pregnancies.

Maternal IL-33 critically regulates tissue remodeling and type 2 immune responses in the uterus during early pregnancy in mice

The pregnant uterus is an immunologically rich organ, with dynamic changes in the inflammatory milieu and immune cell function underlying key stages of pregnancy. Recent studies have implicated dysregulated expression of the interleukin-1 (IL-1) family cytokine, IL-33, and its receptor, ST2, in poor pregnancy outcomes in women, including recurrent pregnancy loss, preeclampsia, and preterm labor. How IL-33 supports pregnancy progression in vivo is not well understood. Here, we demonstrate that maternal IL-33 signaling critically regulates uterine tissue remodeling and immune cell function during early pregnancy in mice. IL-33-deficient dams exhibit defects in implantation chamber formation and decidualization, and abnormal vascular remodeling during early pregnancy. These defects coincide with delays in early embryogenesis, increased resorptions, and impaired fetal and placental growth by late pregnancy. At a cellular level, myometrial fibroblasts, and decidual endothelial and stromal cells, are the main IL-33⁺ cell types in the uterus during decidualization and early placentation, whereas ST2 is expressed by uterine immune populations associated with type 2 immune responses, including ILC2s, Tregs, CD4⁺ T cells, M2- and cDC2-like myeloid cells, and mast cells. Early pregnancy defects in IL-33-deficient dams are associated with impaired type 2 cytokine responses by uterine lymphocytes and fewer Arginase-1⁺ macrophages in the uterine microenvironment. Collectively, our data highlight a regulatory network, involving crosstalk between IL-33-producing nonimmune cells and ST2⁺ immune cells at the maternal-fetal interface, that critically supports pregnancy progression in mice. This work has the potential to advance our understanding of how IL-33 signaling may support optimal pregnancy outcomes in women.

Interleukin-33 regulates the endoplasmic reticulum stress of human myometrium via an influx of calcium during initiation of labor

Background:

Inflammation is currently recognized as one of the major causes of premature delivery. As a member of the interleukin-1β (IL-1β) family, interleukin-33 (IL-33) has been shown to be involved in normal pregnancy as well as a variety of pregnancy-related disorder. This study aims to investigate the potential function of IL-33 in uterine smooth muscle cells during labor.

Methods:

Myometrium samples from term pregnant (≥37 weeks gestation) women were either frozen or cells were isolated and cultured. Immunohistochemistry and western blotting were used to assess the distribution of IL-33. Cultured cells were incubated with lipopolysaccharide (LPS) to mimic inflammation as well as in the presence of 4μ8C (IRE1 inhibitor III) to block endoplasmic reticulum (ER) stress and BAPTA-AM, a calcium chelator.

Results:

LPS reduced the expression of nuclear IL-33 in a time-limited manner and induced ER stress. However, knockdown of IL-33 increased LPS-induced calcium concentration, ER stress and phosphorylation of nuclear factor kappa-B (NF-κB), and P38 mitogen-activated protein kinase (P38 MAPK). In addition, siRNA IL-33 further stimulates LPS enhanced cyclooxygenase-2 (COX-2) expression via NF-κB and p38 pathways. IL-33 expression was decreased in the nucleus with the onset of labor. LPS-induced ER stress and increased expression of the labor-associated gene, COX-2, as well as IL-6 and IL-8 in cultured myometrial cells. IL-33 also increased COX-2 expression, but after it was knocked down, the stimulating effect of LPS on calcium was enhanced. 4μ8C also inhibited the expression of COX-2 markedly. The expression of calcium channels on the membrane and intracellular free calcium ion were both increased which was accompanied by phosphorylated NF-κB and p38.

Conclusions:

These data suggest that IL-33 may be involved in the initiation of labor by leading to stress of the ER via an influx of calcium ions in human uterine smooth muscle cells.

Funding:

This study was supported by grants from the National Natural Science Foundation of China (No. 81300507).

MiR-200b-3p is upregulated in the placental tissues from patients with preeclampsia and promotes the development of preeclampsia via targeting profilin 2

Preeclampsia is a serious pregnancy disorder affecting both maternal and fetal health. However, the pathogenesis of preeclampsia has not been fully understood. This study aimed to investigate the key microRNAs (miRNAs) in the development of preeclampsia. A high-throughput miRNA sequencing analysis for the placental tissues from patients with preeclampsia and healthy controls was conducted, followed by investigation of differentially expressed miRNAs (DEMs) and functional enrichment analysis. Moreover, the expression of a key DEM, named miR-200b-3p, in the preeclampsia patients was validated, and the effects of miR-200b-3p overexpression on the proliferation, migration, and apoptosis of HTR8 trophoblast cells were investigated in vitro. Furthermore, the target gene of miR-200b-3p was investigated based on gene expression profile GSE177049 and miRWalk 2.0 database. The target relationship between miR-200b-3p and profilin 2 (PFN2) was investigated in vitro. A total of 12 DEMs including miR-200b-3p were identified between preeclampsia placental tissues and control placental tissues, which were significantly enriched in several pathways, such as cell adhesion molecules (CAMs) and tight junction. Moreover, increased expression of miR-200b-3p was revealed in the placental tissues of preeclampsia patients, and overexpression of miR-200b-3p suppressed cell proliferation and migration but promoted apoptosis of trophoblast cells. Furthermore, PFN2 was confirmed as a target of miR-200b-3p, and overexpression of PFN2 reversed the inhibitory effects of miR-200b-3p overexpression on trophoblast cell migration. Our findings reveal that miR-200b-3p is upregulated in the placental tissues of patients with preeclampsia and promotes preeclampsia development via PFN2. miR-200b-3p may serve as a promising therapeutic target against preeclampsia.

Emerging Functions of IL-33 in Homeostasis and Immunity

Our understanding of the functions of the IL-1 superfamily cytokine and damage-associated molecular pattern IL-33 continues to evolve with our understanding of homeostasis and immunity. The early findings that IL-33 is a potent driver of type 2 immune responses promoting parasite expulsion, but also inflammatory diseases like allergy and asthma, have been further supported. Yet, as the importance of a type 2 response in tissue repair and homeostasis has emerged, so has the fundamental importance of IL-33 to these processes. In this review, we outline an evolving understanding of IL-33 immunobiology, paying particular attention to how IL-33 directs a network of ST2+ regulatory T cells, reparative and regulatory macrophages, and type 2 innate lymphoid cells that are fundamental to tissue development, homeostasis, and repair.

Expected final online publication date for the Annual Review of Immunology, Volume 40 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Differences in maternal soluble ST2 levels in the third trimester of normal pregnancy versus preeclampsia

BACKGROUND

Preeclampsia is associated with intense inflammatory response in pregnancy, and soluble ST2 (sST2) is pathologically increased in this condition. No data exist regarding maternal sST2 levels in normal pregnancy versus preeclampsia in areas of southeast Asia with an ethnic Malay predominance.

MATERIALS AND METHODS

Patients were sorted into normal pregnancy or preeclampsia. Patients with a history of allergic, inflammatory, or malignant disease were excluded. One sample was taken per patient; all samples were taken during the third trimester of pregnancy. Thirty samples from each group were enrolled in the study, totaling 60 samples. Soluble ST2 levels in maternal plasma were measured using the Presage® ST2 Assay according to manufacturer instructions, and data was analyzed using SPSS 23.

RESULTS

Patients in the preeclampsia group were significantly older than those in the normal pregnancy group (p = 0.01). Most patients with preeclampsia presented as early-onset (n = 23). Both systolic blood pressure (SBP) and diastolic blood pressure (DBP) were significantly higher (p < 0.001) in the preeclampsia group. Mean sST2 level in the preeclampsia group (85.89 ng/ml) was significantly higher than the normal pregnancy group mean (38.3 ng/ml) during the third trimester (p < 0.001). This study also found a correlation between sST2 and preeclampsia (p < 0.001, r = 0.480), SBP (p < 0.001, r = 0.407), and DBP (p = 0.007, r = 0.342), while preeclampsia was found to be the best explanatory variable of sST2 levels (r = 0.468, p < 0.001). sST2 level> 63.66 ng/ml has sensitivity 50% and specificity 93.3%, with AUC of 0.78 [95% CI 0.66 - 0.90], p < 0.001. The sST2 > 63.66 ng/ml has an OR of 14.0 [95% CI 2.82 - 69.6], p < 0.001 for preeclampsia. The dose-response relationship between sST2 level and preeclampsia was linear.

CONCLUSION

Soluble ST2 levels were increased in both normal pregnancy and preeclampsia but were significantly higher in patients with preeclampsia. Preeclampsia was also found to be the best explanatory variable for the increase of sST2 levels in ethnic Malay predominance.

Impaired placental mitophagy and oxidative stress are associated with dysregulated BNIP3 in preeclampsia

Preeclampsia (PE) is a severe multisystem pregnancy complication characterized by gestational hypertension and proteinuria. Bcl-2/adenovirus E1B 19-kDa interacting protein 3 (BNIP3) is a mediator of mitophagy and has been proven to be associated with PE, but the mechanism is not well understood. This study aimed to investigate the role of BNIP3 in PE. Placentae from preeclamptic and normal pregnancies were analyzed by western-blot and transmission electron microscopy to quantify the level of BNIP3 expression and observe the organelle morphologies. Trophoblast cells with knockdown BNIP3 were analyzed by western-blot, immunofluorescence, flow cytometry, migration and invasion assays. BNIP3 expression was suppressed in PE patients. Impaired autophagy and increased mitochondrial damage were observed in PE placentae when compared with normal placentae. Suppression of BNIP3 inhibited Beclin-1 expression and reduced the transformation of LC3-I to LC3-II. In the knockdown BNIP3 group, p62 was overexpressed, ROS accumulated and the apoptotic process was elevated under oxidative stress condition. The knockdown of BNIP3 reduced the colocalization of GFP-LC3 and mitochondria. The findings of this study suggest that dysregulated BNIP3 is associated with impaired mitophagy, oxidative stress, and apoptosis in PE. The study provides new insights into the role of BNIP3 in the pathophysiology of PE.

The implications of the purinergic signaling throughout pregnancy

Purinergic signaling is a necessary mechanism to trigger or even amplify cell communication. Its ligands, notably adenosine triphosphate (ATP) and adenosine, modulate specific membrane-bound receptors in virtually all human cells. Regardless of the stage of the pregnancy, cellular communication between maternal, placental, and fetal cells is the paramount mechanism to sustain its optimal status. In this review, we describe the crucial role of purinergic signaling on the regulation of the maternal-fetal trophic exchanges, immune control, and endocrine exchanges throughout pregnancy. The nature of the modulation of both ATP and adenosine on the embryo-maternal interface, going through placental invasion until birth delivery depends on the general maternal-fetal health state and consequently on the selective activation of their specific receptors. In addition, an increasing number of studies have been demonstrating the pivotal role of ATP and adenosine in modulating deleterious effects of suboptimal conditions of pregnancy. Here, we discuss the role of purinergic signaling on the balance that coordinates the embryo-maternal exchanges and a promising therapeutic venue in the context of pregnancy disorders.

Protective role of IL33 signaling in negative pregnancy outcomes associated with lipopolysaccharide exposure

Interleukin 33 (IL33) signaling has been implicated in the establishment and maintenance of pregnancy and in pregnancy disorders. The goal of this project was to evaluate the role of IL33 signaling in rat pregnancy. The rat possesses hemochorial placentation with deep intrauterine trophoblast invasion; features also characteristic of human placentation. We generated and characterized a germline mutant rat model for IL33 using CRISPR/Cas9 genome editing. IL33 deficient rats exhibited deficits in lung responses to an inflammatory stimulus (Sephadex G-200) and to estrogen-induced uterine eosinophilia. Female rats deficient in IL33 were fertile and exhibited pregnancy outcomes (gestation length and litter size) similar to wild-type rats. Placental weight was adversely affected by the disruption of IL33 signaling. A difference in pregnancy-dependent adaptations to lipopolysaccharide (LPS) exposure was observed between wild-type and IL33 deficient pregnancies. Pregnancy in wild-type rats treated with LPS did not differ significantly from pregnancy in vehicle-treated wild-type rats. In contrast, LPS treatment decreased fetal survival rate, fetal and placental weights, and increased fetal growth restriction in IL33 deficient rats. In summary, a new rat model for investigating IL33 signaling has been established. IL33 signaling participates in the regulation of placental development and protection against LPS-induced fetal and placental growth restriction.

Exosomal miR-486-5p derived from human placental microvascular endothelial cells regulates proliferation and invasion of trophoblasts via targeting IGF1

Preeclampsia (PE) is a serious complication of pregnancy. Exosomes are known to be upregulated in PE. In this study, we sought to investigate the effect of miR-486-5p from human placental microvascular endothelial cells, on the function of trophoblast cells. To investigate the function of human placental microvascular endothelial cell (HPVEC)-derived exosomes on trophoblast cells, HPVECs were treated with hypoxia/reoxygenation (H/R). The separation efficiency of exosomes was determined by transmission electron microscopy, nanosight and Western blot. Cell Counting Kit-8, EdU staining, wound-healing, and transwell assay were performed to detect the effect of exosomally transferred miR-486-5p inhibitor on proliferation, migration and invasion of trophoblast cells. MiRDB and dual-luciferase report assay were used to find the target of miR-486-5p. Our data revealed that miR-486-5p was significantly upregulated in H/R-treated HPVEC-Exo, and miR-486-5p was enriched in HPVEC-Exo. miR-486-5p inhibitor carried by HPVEC-Exo significantly inhibited the proliferation, migration and invasion of trophoblast cells. Insulin-like growth factor 1 (IGF1) was found to be the target of miR-486-5p, and IGF1 overexpression notably reversed the effect of miR-486-5p inhibitor from HPVEC-Exo on trophoblast cell function. In summary, H/R-treated HPVEC-derived exosomally expressing miR-486-5p inhibitor significantly inhibited the proliferation, migration and invasion of trophoblast cells via downregulation of IGF1. The findings from the present study may be useful in the development of treatments for PE.

Overexpressed Hsa_circ_0001326 Contributes to the Decreased Cell Viability in SWAN71 Cells by Regulating MiR-186-5p/p27 Kip1 Axis

Preeclampsia (PE) is a severe pregnancy-specific complication responsible for a majority of maternal and fetal mortality. The dysfunction of trophoblast cells is known to be associated with the etiology of PE. Moreover, elevated expression of hsa_circ_0001326 was found in patients with PE without elucidating specific mechanisms. Thus, this study aimed to investigate the role of hsa_circ_0001326 in the dysfunction of trophoblast cells in vitro. Human trophoblast SWAN71 cells were used in this study. Cell proliferation, apoptosis and cell cycle were detected by 5-ethynyl-2'-deoxyuridine (EdU) staining, cell counting kit-8 assay, Annexin V/propidium iodide (PI) staining and flow cytometry, respectively. Dual luciferase assay was performed to validate the predicted targets. Additionally, Western blot was conducted for protein detection. The results indicated overexpression (OE) of hsa_circ_0001326 remarkably decreased the viability and proliferation of SWAN71 cells. MiR-186-5p was identified as the target of hsa_circ_0001326. Meanwhile, p27 Kip1 was validated as the target of hsa_miR-186-5p. Moreover, the increased apoptosis and decreased migration induced by hsa_circ_0001326 OE were inhibited by p27 Kip1 knockdown. Hsa_circ_0001326 OE upregulated p27 Kip1 and cleaved caspase3 and downregulated CDK2 and cyclin E1 in cells, while these phenomena were reversed by p27 Kip1 knockdown. In addition, hsa_circ_0001326 OE induced G0/G1 cell cycle arrest was also attenuated in the presence of p27 Kip1 knockdown. Taken together, hsa_circ_0001326 OE contributed to the decreased viability of SWAN71 cells by targeting miR-186-5p via upregulation of p27 Kip1. Our findings were helpful to uncover the pathophysiological process of PE, as well as inspire the development of novel targeted therapy against PE.

Involvement of WNT2 in trophoblast cell behavior in preeclampsia development

This study aimed to determine the WNT2 expression in patients with severe preeclampsia and to explore the function of WNT2 dysregulation on the biological behaviors of trophoblast cells. The WNT2 and β-catenin expression in the patients with early-onset and late-onset severe preeclampsia and normal controls was determined. Subsequently, WNT2 was overexpressed and knocked down in HTR8 cells and WNT2 signaling pathway in regulating trophoblast cell proliferation, migration, invasion, and apoptosis were evaluated in vitro. The mRNA and protein expression levels of WNT2 and β-catenin were decreased in patients with preeclampsia, especially early-onset severe preeclampsia. Overexpression of WNT2 promoted trophoblast cell proliferation, migration, and invasion and inhibited apoptosis in vitro, whereas knockdown of WNT2 had opposite effects. The findings of this study reveal that WNT2 and β-catenin were decreased expressed in patients with preeclampsia. Decreased expression of WNT2 may inhibit trophoblast cell proliferation, migration, and invasion but induced apoptosis. WNT2 may serve as a promising biomarker for early detection of preeclampsia.

Overexpression of tissue factor pathway inhibitor 2 attenuates trophoblast proliferation and invasion in preeclampsia

Pre-eclampsia (PE) is a disorder of pregnancy characterized by proteinuria and high blood pressure, affecting 2-8% of pregnancies worldwide. Previous studies have shown that PE is closely associated with trophoblast cell dysfunction. Here, we investigated the role of tissue factor pathway inhibitor-2 (TFPI-2) in regulating the biological processes of trophoblast cells. The TFPI-2 levels in plasma samples and placental tissues were tested by ELISA, immunohistochemistry, qRT-PCR, and western blot. HTR8/Svneo cell line was used to simulate the primary trophoblast cells and H/R culture was applied to mimic the oxidative stress state of PE. MTT assay, Annexin V/propidium iodide (PI) apoptosis assay, and transwell assay were used to determine the cell proliferation, apoptosis, and invasion. The expression levels of matrix metalloproteinases (MMPs) were evaluated by western blot. The expression of TFPI-2 was remarkably up-regulated in both the serum and placenta of PE patients. Hypoxia/reoxygenation increased the expression of TFPI-2 in HTR-8/SVneo cell line. TFPI-2 promoted that cell proliferation and inhibited the cell apoptosis of HTR8/SVneo cells in H/R condition. In addition, downregulation of TFPI-2 increased the cell invasion and the expression of MMP2 and MMP9. This study reveals that TFPI-2 plays a crucial role in monitoring the biological function of trophoblast cells, which might provide theoretical basis and therapeutic targets for the treatment of PE.

Dynamic Expression of Interleukin-33 and ST2 in the Mouse Reproductive Tract Is Influenced by Superovulation

Interleukin-33 (IL-33) is an IL-1 family cytokine with pleiotropic effects on diverse cell types. Dysregulated IL-33 signaling has been implicated in pregnancy-related disorders, including preeclampsia and recurrent pregnancy loss, and in ovarian function in women undergoing controlled ovarian stimulation for in vitro fertilization. To date, expression of IL-33 and its receptor subunit, ST2, in the female reproductive tract remains poorly characterized. We identify IL-33-expressing oocytes surrounded by ST2-expressing granulosa cells at all stages of follicular development, in addition to IL-33⁺ and ST2⁺ non-endothelial cells in the ovarian stroma and theca layer in ovaries from adult mice. These expression patterns are similar in estrus- and diestrus-stage adults and in pubescent mice, suggesting a role for IL-33 signaling in ovarian function throughout development and in the estrous cycle. In the uterus, we find expression of IL-33 and ST2 in glandular and luminal epithelia during estrus and at the initiation of pregnancy. Uterine IL-33 expression was modulated by the estrous cycle and was reduced in pubescent females. Last, superovulation increases transcripts for IL-33 and the soluble form of ST2 (sST2) in ovaries, and for IL-33 in uteri. Collectively, our findings lay the foundation for studies identifying cell type-specific requirements for IL-33/ST2 signaling in the establishment and maintenance of mouse pregnancy.

Doppler ultrasound and photoplethysmographic assessment for identifying pregnancy-induced hypertension

The current study investigated whether placentation and systemic inflammation are associated with pregnancy-induced hypertension (PIH) or pre-eclampsia (PE), and evaluated some measurable indexes for assessment of maternal factors contributing to high-risk pregnancy. Photoplethysmographic reflection index (PPG RI), uterine artery (UtA) pulsatile index (PI) and reflection index (RI), as well as maternal serum placental growth factor (PlGF) and soluble endoglin (sEng) were measured in pregnant women with singleton pregnancy at the gestational age of 22 to 23 weeks. Study subjects were women with normal pregnancy (NP, n=24), PIH (n=14) and PE (n=16). It was found that individuals in the PIH group exhibited higher UtA RI and UtA PI values, as well as PPG RI values compared with individuals in the NP group. Individuals in the PE group had the highest UtA RI, UtA PI and PPG RI values among these 3 groups. UtA and PPG results were significantly different in PIH and PE groups compared with the NP group. Significant differences were found in both PlGF and sEng levels between PIH and PE groups. A strong inverse across-subject correlation was found between PlGF and sEng levels. A weak inverse correlation was found between PlGF and UtA RI, and PlGF and UtA PI. A moderate inverse correlation was found between PlGF and PPG RI. A moderate positive correlation was found between either sEng and UtA RI or sEng and UtA PI. A very strong positive correlation was found between sEng and PPG RI. Taken together, the current results indicated that maternal effects related to cardiovascular adaptation to placentation and systemic inflammation exhibited significant differences between NP and PIH or PE groups. Therefore, assessment of UtA and PPG could be used for identifying high-risk pregnancy.

Up regulation of miR-96-5p is responsible for TiO2 NPs induced invasion dysfunction of human trophoblastic cells via disturbing Ezrin mediated cytoskeletons arrangement

Titanium dioxide nanoparticles (TiO₂ NPs) are used extensively in our daily lives, and their toxic effects on the placenta have been reported. Animal studies indicated that placental development is impaired after maternal exposure of TiO₂ NPs, but the underlying mechanisms remain largely unknown. In the present study, we used a human trophoblast-derived cell, HTR8-SVneo, to determine how TiO₂ NPs affected placental functions, and found out potential reversal targets. TEM was employed for TiO₂ NPs morphology observation and uptake assessment. RT-PCR was used to detect the expression of both mRNA and miRNA, and western blotting was used for protein examination. Cell invasion ability was evaluated by Transwell assay, and cytoskeletons were observed by immunofluorescence combined with confocal microscope examination. We found that TiO₂ NPs disrupted cytoskeletons and impaired cell invasion ability. Further investigations showed that TiO₂ NPs increased the expression of a microRNA (miR-96-5p), which targeted and down-regulated the translation of EZR mRNA, a gene that encodes ezrin protein, and affected the cell cytoskeletons and ultimately cell invasion ability. When the expression of miR-96-5p was down-regulated, the expression level of ezrin protein was also reversed, and cell invasion ability was partially restored. Collectively, we determined how miR-96-5p mediates TiO₂ NP-induced placental dysfunction, and provided a potential rescue target for future therapy.

microRNA-520c-3p suppresses NLRP3 inflammasome activation and inflammatory cascade in preeclampsia by downregulating NLRP3

BACKGROUND

The pathogenesis of preeclampsia (PE) is suggested to be a consequence of inflammation. Previously conducted investigations on nod-like receptor pyrin domain-containing 3 (NLRP3) have shed light to its crucial role in PE. Furthermore, microRNA-520c-3p (miR-520c-3p) is observed to be implicated in inflammation. Therefore, the current study aimed to explore the role of miR-520c-3p in inflammatory cascade of PE by targeting NLRP3.

METHODS

Microarray analyses were performed to screen differentially expressed genes associated with PE, and the potential relationship between miR-520c-3p and NLRP3 was analyzed. PE and normal placenta tissues were collected to determine the levels of inflammatory cytokines (IL-18, IL-33, IL-1β, IL-10, and TNF-α), miR-520c-3p and NLRP3. Hypoxic HTR8/SVneo cells were transfected with oe-NLRP3, si-NLRP3 or miR-520c-3p mimic to elucidate the functional role of NLRP3 or miR-520c-3p in the inflammatory cascade in PE, followed by the evaluation of levels of inflammatory cytokines and NLRP3 inflammasomes (NLRP3, ASC and caspase-1). Additionally, the HTR8/SVneo cell migration and invasion were evaluated.

RESULTS

An upregulation of NLRP3, IL-18, IL-1β and TNF-α, and downregulation of miR-520c-3p, IL-33 and IL-10 were observed in PE placenta tissues. NLRP3 was found to be a target gene of miR-520c-3p. HTR8/SVneo cells after hypoxia transfected with si-NLRP3 or miR-520c-3p mimic exhibited decreased levels of inflammatory cytokines and NLRP3 inflammasomes, in addition to increased IL-10 and IL-33 levels. Moreover, enhanced migration and invasion abilities were observed in cells transfected with si-NLRP3.

CONCLUSION

Collectively, miR-520c-3p could potentially inhibit NLRP3 inflammasome activation and inflammatory cascade in PE by downregulating NLRP3, highlighting the potential of miR-520c-3p as a therapeutic target for PE treatment.