Abnormal development of placenta in HtrA1-deficient mice

Cystine-knot peptide inhibitors of HTRA1 bind to a cryptic pocket within the active site region

Cystine-knot peptides (CKPs) are naturally occurring peptides that exhibit exceptional chemical and proteolytic stability. We leveraged the CKP carboxypeptidase A1 inhibitor as a scaffold to construct phage-displayed CKP libraries and subsequently screened these collections against HTRA1, a trimeric serine protease implicated in age-related macular degeneration and osteoarthritis. The initial hits were optimized by using affinity maturation strategies to yield highly selective and potent picomolar inhibitors of HTRA1. Crystal structures, coupled with biochemical studies, reveal that the CKPs do not interact in a substrate-like manner but bind to a cryptic pocket at the S1' site region of HTRA1 and abolish catalysis by stabilizing a non-competent active site conformation. The opening and closing of this cryptic pocket is controlled by the gatekeeper residue V221, and its movement is facilitated by the absence of a constraining disulfide bond that is typically present in trypsin fold serine proteases, thereby explaining the remarkable selectivity of the CKPs. Our findings reveal an intriguing mechanism for modulating the activity of HTRA1, and highlight the utility of CKP-based phage display platforms in uncovering potent and selective inhibitors against challenging therapeutic targets.

Regulation of sexually dimorphic placental adaptation in LPS exposure-induced intrauterine growth restriction

BACKGROUND

Sexual dimorphism in placental physiology affects the functionality of placental adaptation during adverse pregnancy. Defects of placental function compromise fetal programming, affecting the offspring's adult life. However, studies focusing on the relationship between sex-specific placental adaptation and consequent fetal maldevelopment under sub-optimal uterus milieu are still elusive.

METHODS

Here, we investigated the effects of maternal lipopolysaccharide (LPS) exposure between placental sex. Pregnant ICR mice received intraperitoneal injection of phosphate-buffered saline or 100, 200, and 400 µg/kg LPS on the gestational day (GD) 15.5. To determine whether prenatal maternal LPS exposure resulted in complicated pregnancy outcomes, survival rate of embryos was calculated and the growth of embryos and placentas was examined. To elucidate global transcriptomic changes occurring in the placenta, total RNA-sequencing (RNA-seq) was performed in female and male placentas.

RESULTS

LPS administration induced placental inflammation in both sexes at GD 17.5. Prenatal infection resulted in growth retardation in both sexes of embryos, and especially more prevalently in male. Impaired placental development was observed in a sex-specific manner. LPS 400 µg/kg reduced the percentage area of the labyrinth in females and junctional zone in males, respectively. RNA-sequencing revealed widespread sexually dimorphic transcriptional changes in placenta. In particular, representative changes were involved in biological processes such as trophoblast differentiation, nutrient/ion transporter, pregnancy, and immune system.

CONCLUSIONS

Our results present the sexually dimorphic responses of placental physiology in intrauterine growth restriction model and provide tentative relationship further to be elucidated between sex-biased placental functional change and long-term effects on the offspring's later life.

10q26 - The enigma in age-related macular degeneration

Despite comprehensive research efforts over the last decades, the pathomechanisms of age-related macular degeneration (AMD) remain far from being understood. Large-scale genome wide association studies (GWAS) were able to provide a defined set of genetic aberrations which contribute to disease risk, with the strongest contributors mapping to distinct regions on chromosome 1 and 10. While the chromosome 1 locus comprises factors of the complement system with well-known functions, the role of the 10q26-locus in AMD-pathophysiology remains enigmatic. 10q26 harbors a cluster of three functional genes, namely PLEKHA1, ARMS2 and HTRA1, with most of the AMD-associated genetic variants mapping to the latter two genes. High linkage disequilibrium between ARMS2 and HTRA1 has kept association studies from reliably defining the risk-causing gene for long and only very recently the genetic risk region has been narrowed to ARMS2, suggesting that this is the true AMD gene at this locus. However, genetic associations alone do not suffice to prove causality and one or more of the 14 SNPs on this haplotype may be involved in long-range control of gene expression, leaving HTRA1 and PLEKHA1 still suspects in the pathogenic pathway. Both, ARMS2 and HTRA1 have been linked to extracellular matrix homeostasis, yet their exact molecular function as well as their role in AMD pathogenesis remains to be uncovered. The transcriptional regulation of the 10q26 locus adds an additional level of complexity, given, that gene-regulatory as well as epigenetic alterations may influence expression levels from 10q26 in diseased individuals. Here, we provide a comprehensive overview on the 10q26 locus and its three gene products on various levels of biological complexity and discuss current and future research strategies to shed light on one of the remaining enigmatic spots in the AMD landscape.

HtrA1 in Gestational Diabetes Mellitus: A Possible Biomarker?

BACKGROUND

The high-temperature requirement A 1 (HtrA1) is a multidomain secretory protein with serine-protease activity, expressed in many tissues, including placenta, where its expression is higher in the first trimester, suggesting an association of this serine protease in early phases of human placenta development. In this study, we evaluated maternal serum HtrA1 levels in the first and third trimester of gestation. In particular, we evaluated a possible role of HtrA1 as an early marker of gestational diabetes mellitus (GDM) in the first trimester of gestation.

METHODS

We evaluated HtrA1 serum levels in the third trimester (36-40 weeks) in normal pregnancies (n = 20) and GDM pregnancies (n = 20) by using ELISA analysis. Secondly, we performed the same analysis by using the first trimester sera (10-12 weeks) of healthy pregnant women that will develop a normal pregnancy (n = 210) or GDM (n = 28) during pregnancy.

RESULTS

We found that HtrA1 serum levels in the third trimester were higher in pregnancies complicated by GDM. Interestingly, higher HtrA1 serum levels were also found in the first trimester in women developing GDM later during the second-third trimester. No significant differences in terms of maternal age and gestational age were found between cases and controls. Women with GDM shown significantly higher pre-pregnancy BMI values compared to controls. Moreover, the probability of GDM occurrence significantly increased with increasing HtrA1 levels and BMI values. The ROC curve showed a good accuracy in predicting GDM, with an AUC of 0.74 (95%CI: 0.64-0.92).

CONCLUSIONS

These results suggest an important role of HtrA1 as an early predictive marker of GDM in the first trimester of gestation, showing a significative clinical relevance for prevention of this disease.

Role of microRNAs in trophoblast invasion and spiral artery remodeling: Implications for preeclampsia

It is now well-established that microRNAs (miRNAs) are important regulators of gene expression. The role of miRNAs in placental development and trophoblast function is constantly expanding. Trophoblast invasion and their ability to remodel uterine spiral arteries are essential for proper placental development and successful pregnancy outcome. Many miRNAs are reported to be dysregulated in pregnancy complications, especially preeclampsia and they exert various regulatory effects on trophoblasts. In this review, we provide a brief overview of miRNA biogenesis and their mechanism of action, as well as of trophoblasts differentiation, invasion and spiral artery remodeling. We then discuss the role of miRNAs in trophoblasts invasion and spiral artery remodeling, focusing on miRNAs that have been thoroughly investigated, especially using multiple model systems. We also discuss the potential role of miRNAs in the pathogenesis of preeclampsia.

Porphyromonas gingivalis-mediated disruption in spiral artery remodeling is associated with altered uterine NK cell populations and dysregulated IL-18 and Htra1

Impaired spiral artery remodeling (IRSA) underpins the great obstetrical syndromes. We previously demonstrated that intrauterine infection with the periodontal pathogen, Porphyromonas gingivalis, induces IRSA in rats. Since our previous studies only examined the end stage of arterial remodeling, the aim of this study was to identify the impact of P. gingivalis infection on the earlier stages of remodeling. Gestation day (GD) 11 specimens, a transition point between trophoblast-independent remodeling and the start of extravillous trophoblast invasion, were compared to late stage GD18 tissues. P. gingivalis was found in decidual stroma of GD11 specimens that already had reduced spiral artery remodeling defined as smaller arterial lumen size, increased retention of vascular smooth muscle, and decreased invasion by extravillous trophoblasts. At GD11, P. gingivalis-induced IRSA coincided with altered uterine natural killer (uNK) cell populations, decreased placental bed expression of interleukin-18 (IL-18) with increased production of temperature requirement A1 (Htra1), a marker of oxidative stress. By GD18, placental bed IL-18 and Htra1 levels, and uNK cell numbers were equivalent in control and infected groups. However, infected GD18 placental bed specimens had decreased TNF + T cells. These results suggest disturbances in placental bed decidual stroma and uNK cells are involved in P. gingivalis-mediated IRSA.

Placental multi-omics integration identifies candidate functional genes for birthweight

Abnormal birthweight is associated with increased risk for cardiometabolic diseases in later life. Although the placenta is critical to fetal development and later life health, it has not been integrated into largescale functional genomics initiatives, and mechanisms of birthweight-associated variants identified by genome wide association studies (GWAS) are unclear. The goal of this study is to provide functional mechanistic insight into the causal pathway from a genetic variant to birthweight by integrating placental methylation and gene expression with established GWAS loci for birthweight. We identify placental DNA methylation and gene expression targets for several birthweight GWAS loci. The target genes are broadly enriched in cardiometabolic, immune response, and hormonal pathways. We find that methylation causally influences WNT3A, CTDNEP1, and RANBP2 expression in placenta. Multi-trait colocalization identifies PLEKHA1, FES, CTDNEP1, and PRMT7 as likely functional effector genes. These findings reveal candidate functional pathways that underpin the genetic regulation of birthweight via placental epigenetic and transcriptomic mechanisms. Clinical trial registration; ClinicalTrials.gov, NCT00912132.

Interplay between HTRA1 and classical signalling pathways in organogenesis and diseases

The high temperature requirement factor A1 (HTRA1) is a serine protease which modulates an array of signalling pathways driving basal biological processes. HTRA1 plays a significant role in cell proliferation, migration and fate determination, in addition to controlling protein aggregates through refolding, translocation or degradation. The mutation of HTRA1 has been implicated in a plethora of disorders and this has also led to its growing interest as drug therapy target. This review details the involvement of HTRA1 in certain signalling pathways, namely the transforming growth factor beta (TGF-β), canonical Wingless/Integrated (WNT) and NOTCH signalling pathways during organogenesis and various disease pathogenesis such as preeclampsia, age-related macular degeneration (AMD), small vessel disease and cancer. We have also explored possible avenues of exploiting the serine proteases for therapeutic management of these disorders.

Overview of Human HtrA Family Proteases and Their Distinctive Physiological Roles and Unique Involvement in Diseases, Especially Cancer and Pregnancy Complications

The mammalian high temperature requirement A (HtrA) proteins are a family of evolutionarily conserved serine proteases, consisting of four homologs (HtrA1-4) that are involved in many cellular processes such as growth, unfolded protein stress response and programmed cell death. In humans, while HtrA1, 2 and 3 are widely expressed in multiple tissues with variable levels, HtrA4 expression is largely restricted to the placenta with the protein released into maternal circulation during pregnancy. This limited expression sets HtrA4 apart from the rest of the family. All four HtrAs are active proteases, and their specific cellular and physiological roles depend on tissue type. The dysregulation of HtrAs has been implicated in many human diseases such as cancer, arthritis, neurogenerative ailments and reproductive disorders. This review first discusses HtrAs broadly and then focuses on the current knowledge of key molecular characteristics of individual human HtrAs, their similarities and differences and their reported physiological functions. HtrAs in other species are also briefly mentioned in the context of understanding the human HtrAs. It then reviews the distinctive involvement of each HtrA in various human diseases, especially cancer and pregnancy complications. It is noteworthy that HtrA4 expression has not yet been reported in any primary tumour samples, suggesting an unlikely involvement of this HtrA in cancer. Collectively, we accentuate that a better understanding of tissue-specific regulation and distinctive physiological and pathological roles of each HtrA will improve our knowledge of many processes that are critical for human health.

Placental HTRA1 cleaves α1-antitrypsin to generate a NET-inhibitory peptide

Neutrophil extracellular traps (NETs) are important components of innate immunity. Neonatal neutrophils (polymorphonuclear leukocytes [PMNs]) fail to form NETs due to circulating NET-inhibitory peptides (NIPs), cleavage fragments of α1-antitrypsin (A1AT). How fetal and neonatal blood NIPs are generated remains unknown, however. The placenta expresses high-temperature requirement serine protease A1 (HTRA1) during fetal development, which can cleave A1AT. We hypothesized that placentally expressed HTRA1 regulates the formation of NIPs and that NET competency changed in PMNs isolated from neonatal HTRA1 knockout mice (HTRA1-/-). We found that umbilical cord blood plasma has elevated HTRA1 levels compared with adult plasma and that recombinant and placenta-eluted HTRA1 cleaves A1AT to generate an A1AT cleavage fragment (A1ATM383S-CF) of molecular weight similar to previously identified NIPs that block NET formation by adult neutrophils. We showed that neonatal mouse pup plasma contains A1AT fragments that inhibit NET formation by PMNs isolated from adult mice, indicating that NIP generation during gestation is conserved across species. Lipopolysaccharide-stimulated PMNs isolated from HTRA1+/+ littermate control pups exhibit delayed NET formation after birth. However, plasma from HTRA1-/- pups had no detectable NIPs, and PMNs from HTRA1-/- pups became NET competent earlier after birth compared with HTRA1+/+ littermate controls. Finally, in the cecal slurry model of neonatal sepsis, A1ATM383S-CF improved survival in C57BL/6 pups by preventing pathogenic NET formation. Our data indicate that placentally expressed HTRA1 is a serine protease that cleaves A1AT in utero to generate NIPs that regulate NET formation by human and mouse PMNs.

Maternal microbiome in preeclampsia pathophysiology and implications on offspring health

Preeclampsia is a devastating hypertensive pregnancy disorder that currently affects 2%–8% of pregnancies worldwide. It is associated with maternal and fetal mortality and morbidity and adverse health outcomes both in mom and offspring beyond pregnancy. The pathophysiology is not completely understood, and there are no approved therapies to specifically treat for the disease, with only few therapies approved to manage symptoms. Recent advances suggest that aberrations in the composition of the microbiome may play a role in the pathogenesis of various diseases including preeclampsia. The maternal and uteroplacental environments greatly influence the long‐term health outcomes of the offspring through developmental programming mechanisms. The current review summarizes recent developments on the role of the microbiome in adverse pregnancy outcomes with a focus on preeclampsia. It also discusses the potential role of the maternal microbiome in fetal programming; explores gut‐targeted therapeutics advancement and their implications in the treatment of preeclampsia.

Proteome reprogramming of endometrial epithelial cells by human trophectodermal small extracellular vesicles reveals key insights into embryo implantation

Embryo implantation into the receptive endometrium is critical in pregnancy establishment, initially requiring reciprocal signalling between outer layer of the blastocyst (trophectoderm cells) and endometrial epithelium; however, factors regulating this crosstalk remain poorly understood. Although endometrial extracellular vesicles (EVs) are known to signal to the embryo during implantation, the role of embryo-derived EVs remains largely unknown. Here, we provide a comprehensive proteomic characterisation of a major class of EVs, termed small EVs (sEVs), released by human trophectoderm cells (Tsc-sEVs) and their capacity to reprogram protein landscape of endometrial epithelium in vitro. Highly purified Tsc-sEVs (30-200 nm, ALIX⁺ , TSG101⁺ , CD9/63/81⁺ ) were enriched in known players of implantation (LIFR, ICAM1, TAGLN2, WNT5A, FZD7, ROR2, PRICKLE2), antioxidant activity (SOD1, PRDX1/4/6), tissue integrity (EZR, RAC1, RHOA, TNC), and focal adhesions (FAK, ITGA2/V, ITGB1/3). Functionally, Tsc-sEVs were taken up by endometrial cells, altered transepithelial electrical resistance, and upregulated proteins implicated in embryo attachment (ITGA2/V, ITGB1/3), immune regulation (CD59, CD276, LGALS3), and antioxidant activity (GPX1/3/4, PRDX1/2/4/5/6): processes that are critical for successful implantation. Collectively, we provide critical insights into Tsc-sEV-mediated regulation of endometrial function that contributes to our understanding of the molecular basis of implantation.

HTRA family proteins in pregnancy outcome

HTRA (High temperature requirement protease A) family proteins includes HTRA1 (L56 or PRSS11), HTRA2/Omi, HTRA3 (PRSP) and HTRA4. These are oligomeric serine proteases highly conserved from bacteria to humans and are involved in a variety of biological functions including the maintenance of normal cell physiology and pathogenicity such as cell growth, apoptosis, neurodegenerative disorders, inflammation diseases and cancer. These proteins are normally expressed in placental villi during all pregnancy but their expression is found to be altered in pathological pregnancies suggesting a possible role of those proteins in the development of human placenta. Moreover, some HTRA family proteins have also been found in maternal blood and were impaired in pathological pregnancy suggesting a possible role of some of these proteins as early markers of pregnancy outcome. The aim of this review is to summarize the data currently available on the role of HTRA family proteins in pregnancy focalizing their role in pregnancy complications such as Preeclampsia (PE), IntraUterine Growth Restriction (IUGR) and Spontaneus PreTerm Birth (SPTB).

Transient Receptor Potential Vanilloid 6 (TRPV6) Proteins Control the Extracellular Matrix Structure of the Placental Labyrinth

Calcium-selective transient receptor potential Vanilloid 6 (TRPV6) channels are expressed in fetal labyrinth trophoblasts as part of the feto-maternal barrier, necessary for sufficient calcium supply, embryo growth, and bone development during pregnancy. Recently, we have shown a less- compact labyrinth morphology of Trpv6-deficient placentae, and reduced Ca²⁺ uptake of primary trophoblasts upon functional deletion of TRPV6. Trpv6^-/- trophoblasts show a distinct calcium-dependent phenotype. Deep proteomic profiling of wt and Trpv6^-/- primary trophoblasts using label-free quantitative mass spectrometry leads to the identification of 2778 proteins. Among those, a group of proteases, including high-temperature requirement A serine peptidase 1 (HTRA1) and different granzymes are more abundantly expressed in Trpv6^-/- trophoblast lysates, whereas the extracellular matrix protein fibronectin and the fibronectin-domain-containing protein 3A (FND3A) were markedly reduced. Trpv6^-/-placenta lysates contain a higher intrinsic proteolytic activity increasing fibronectin degradation. Our results show that the extracellular matrix formation of the placental labyrinth depends on TRPV6; its deletion in trophoblasts correlates with the increased expression of proteases controlling the extracellular matrix in the labyrinth during pregnancy.

The Serine Protease HTRA-1 Is a Biomarker for ROP and Mediates Retinal Neovascularization

Retinopathy of prematurity (ROP) is a blinding aberrancy of retinal vascular maturation in preterm infants. Despite delayed onset after preterm birth, representing a window for therapeutic intervention, we cannot prevent or cure ROP blindness. A natural form of ROP protection exists in the setting of early-onset maternal preeclampsia, though is not well characterized. As ischemia is a central feature in both ROP and preeclampsia, we hypothesized that angiogenesis mediators may underlie this protection. To test our hypothesis we analyzed peripheral blood expression of candidate proteins with suggested roles in preeclamptic and ROP pathophysiology and with a proposed angiogenesis function (HTRA-1, IGF-1, TGFβ-1, and VEGF-A). Analysis in a discovery cohort of 40 maternal-infant pairs found that elevated HTRA-1 (high-temperature requirement-A serine peptidase-1) was significantly associated with increased risk of ROP and the absence of preeclampsia, thus fitting a model of preeclampsia-mediated ROP protection. We validated these findings and further demonstrated a dose-response between systemic infant HTRA-1 expression and risk for ROP development in a larger and more diverse validation cohort consisting of preterm infants recruited from two institutions. Functional analysis in the oxygen-induced retinopathy (OIR) murine model of ROP supported our systemic human findings at the local tissue level, demonstrating that HtrA-1 expression is elevated in both the neurosensory retina and retinal pigment epithelium by RT-PCR in the ROP disease state. Finally, transgenic mice over-expressing HtrA-1 demonstrate greater ROP disease severity in this model. Thus, HTRA-1 may underlie ROP protection in preeclampsia and represent an avenue for disease prevention, which does not currently exist.

Circular RNA circ_0111277 attenuates human trophoblast cell invasion and migration by regulating miR-494/HTRA1/Notch-1 signal pathway in pre-eclampsia

Mounting evidence has revealed that impaired spiral artery remodeling, placental dysfunction, and inadequate trophoblast invasion are closely correlated with the etiology and pathogenesis of pre-eclampsia (PE). Moreover, defective trophoblast invasion may trigger poor maternal-fetal circulation and placental hypoxia, leading to PE. However, the detailed molecular pathology of PE remains unclear. Although circRNAs, as a new type of stable and abundant endogenous noncoding RNA, have been proven to be essential to the pathogenesis of various diseases, their role in PE requires further verification. In this context, it is necessary to unveil the roles of circRNAs in regulating the migration and invasion of extravillous trophoblasts. In this study, using quantitative real-time PCR, we confirmed that hsa_circ_0111277 was upregulated in PE placentas relative to the level in normal pregnancy placentas. In addition, positive correlations between hsa_circ_0111277 expression and PE-related factors (proteinuria level at 24 h and placental weight) were identified by Pearson's analysis based on the clinical data of 25 PE patients. Moreover, fluorescence in situ hybridization analysis illustrated that circ_0111277 was preferentially localized within the cytoplasm. Mechanistically, circ_0111277 sponged hsa-miR-494-3p in trophoblast cells to attenuate the latter's repression by regulating HTRA1/Notch-1 expression. In conclusion, trophoblast cell migration and invasion were shown to be promoted and modulated by the hsa_circ_0111277/miR-494-3p/HTRA1/Notch-1 axis, which provides useful insight for exploring a new therapeutic approach for PE.

Preeclampsia beyond pregnancy: long-term consequences for mother and child

Preeclampsia is defined as new-onset hypertension after the 20th wk of gestation along with evidence of maternal organ failure. Rates of preeclampsia have steadily increased over the past 30 yr, affecting ∼4% of pregnancies in the United States and causing a high economic burden (22, 69). The pathogenesis is multifactorial, with acknowledged contributions by placental, vascular, renal, and immunological dysfunction. Treatment is limited, commonly using symptomatic management and/or early delivery of the fetus (6). Along with significant peripartum morbidity and mortality, current research continues to demonstrate that the consequences of preeclampsia extend far beyond preterm delivery. It has lasting effects for both mother and child, resulting in increased susceptibility to hypertension and chronic kidney disease (45, 54, 115, 116), yielding lifelong risk to both individuals. This review discusses recent guideline updates and recommendations along with current research on these long-term consequences of preeclampsia.

Association between serum estradiol level on the human chorionic gonadotrophin administration day and clinical outcome

BACKGROUND

Estradiol, as an important hormone in follicular development and endometrial receptivity, is closely related to clinical outcomes of fresh in vitro fertilization embryo transfer (IVF-ET) cycles. The aim of this retrospective study was to evaluate the association between elevated serum estradiol (E2) levels on the day of human chorionic gonadotrophin (hCG) administration and IVF-ET pregnancy and birth outcomes.

METHODS

A total of 1771 infertile patients with their first fresh IVF-ET cycles were analyzed retrospectively between January 2011 and January 2016 in Peking University First Hospital. Patients were categorized by serum E2 levels on the day of hCG administration into six groups: group 1 (serum E2 levels ≤ 1000 pg/mL, n = 205), group 2 (serum E2 levels 1001-2000 pg/mL, n = 457), group 3 (serum E2 levels 2001-3000 pg/mL, n = 425), group 4 (serum E2 levels 3001-4000 pg/mL, n = 310), group 5 (serum E2 levels 4001-5000 pg/mL, n = 237), and group 6 (serum E2 levels > 5000 pg/mL, n = 137). The retrieved oocyte and MII oocyte numbers and implantation and clinical pregnancy rates of the groups were compared as the first objective of the study. For the 360 women with singleton births among all patients, the area under the corresponding receiver operating characteristic curve (ROC curve) was calculated to assess the predictive value of the E2 change for the probability of low birth weight (LBW) infants as the second objective.

RESULTS

The retrieved oocyte and MII oocyte numbers and implantation and clinical pregnancy rates gradually increased from groups 1 to 5 but decreased in group 6. The parameters of group 1 were statistically worse than those of the other groups, from group 2 to group 6 (the number of retrieved oocytes, t = 13.096, t = 23.307, t = 23.086, t = 26.376, t = 19.636, P < 0.003; the number of retrieved MII oocytes, t = 10.856, t = 20.868, t = 21.874, t = 23.374, t = 19.092, P < 0.003; the implantation rate, χ = 12.179, χ = 22.239, χ = 23.993, χ = 23.344, χ = 16.758, P < 0.003; the clinical pregnancy rate, χ = 16.415, χ = 28.074, χ = 35.387, χ = 37.025, χ = 24.590, P < 0.003). ROC analysis revealed that when a serum peak E2 of 3148 pg/mL was used to predict LBW.

CONCLUSIONS

The results indicate that serum E2 levels have a concentration-dependent effect on clinical outcomes. The optimal range of the E2 level during a fresh IVF-ET cycle is 1000 to 3148 pg/mL.

The brain-placental axis: Therapeutic and pharmacological relevancy to pregnancy

The placenta plays a critical role in mammalian reproduction. Although it is a transient organ, its function is indispensable to communication between the mother and fetus, and supply of nutrients and oxygen to the growing fetus. During pregnancy, the placenta is vulnerable to various intrinsic and extrinsic conditions which can result in increased risk of fetal neurodevelopmental disorders as well as fetal death. The placenta controls the neuroendocrine secretion in the brain as a means of adaptive processes to safeguard the fetus from adverse programs, to optimize fetal development and other physiological changes necessary for reproductive success. Although a wealth of information is available on neuroendocrine functions in pregnancy, they are largely limited to the regulation of hypothalamus-pituitary-adrenal/gonad (HPA/ HPG) axis, particularly the oxytocin and prolactin system. There is a major gap in knowledge on systems-level functional interaction between the brain and placenta. In this review, we aim to outline the current state of knowledge about the brain-placental axis with description of the functional interactions between the placenta and the maternal and fetal brain. While describing the brain-placental interactions, a special emphasis has been given on the therapeutics and pharmacology of the placental receptors to neuroligands expressed in the brain during gestation. As a key feature of this review, we outline the prospects of integrated pharmacogenomics, single-cell sequencing and organ-on-chip systems to foster priority areas in this field of research. Finally, we remark on the application of precision genomics approaches to study the brain-placental axis in order to accelerate personalized medicine and therapeutics to treat placental and fetal brain disorders.

Genetic regulation of the placental transcriptome underlies birth weight and risk of childhood obesity

GWAS identified variants associated with birth weight (BW), childhood obesity (CO) and childhood BMI (CBMI), and placenta is a critical organ for fetal development and postnatal health. We examined the role of placental transcriptome and eQTLs in mediating the genetic causes for BW, CO and CBMI, and applied integrative analysis (Colocalization and MetaXcan). GWAS loci associated with BW, CO, and CBMI were substantially enriched for placenta eQTLs (6.76, 4.83 and 2.26 folds, respectively). Importantly, compared to eQTLs of adult tissues, only placental eQTLs contribute significantly to both anthropometry outcomes at birth (BW) and childhood phenotypes (CO/CBMI). Eight, six and one transcripts colocalized with BW, CO and CBMI risk loci, respectively. Our study reveals that placental transcription in utero likely plays a key role in determining postnatal body size, and as such may hold new possibilities for therapeutic interventions to prevent childhood obesity.

Loss of HtrA1 serine protease induces synthetic modulation of aortic vascular smooth muscle cells

Homozygous mutations of human HTRA1 cause cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL). HtrA1-/- mice were examined for arterial abnormalities. Although their cerebral arteries were normal, the thoracic aorta was affected in HtrA1-/- mice. The number of vascular smooth muscle cells (VSMCs) in the aorta was increased in HtrA1-/- mice of 40 weeks or younger, but decreased thereafter. The cross-sectional area of the aorta was increased in HtrA1-/- mice of 40 weeks or older. Aortic VSMCs isolated from HtrA1-/- mice rapidly proliferated and migrated, produced high MMP9 activity, and were prone to oxidative stress-induced cell death. HtrA1-/- VSMCs expressed less smooth muscle α-actin, and more vimentin and osteopontin, and responded to PDGF-BB more strongly than wild type VSMCs, indicating that HtrA1-/- VSMCs were in the synthetic phenotype. The elastic lamina was disrupted, and collagens were decreased in the aortic media. Calponin in the media was decreased, whereas vimentin and osteopontin were increased, suggesting a synthetic shift of VSMCs in vivo. Loss of HtrA1 therefore skews VSMCs toward the synthetic phenotype, induces MMP9 expression, and expedites cell death. We propose that the synthetic modulation is the primary event that leads to the vascular abnormalities caused by HtrA1 deficiency.

Inactivation of the serine protease HTRA1 inhibits tumor growth by deregulating angiogenesis

The serine protease HTRA1 is involved in several vascular diseases and its expression is often deregulated in cancer. We aimed at identifying how HTRA1 in the vasculature affects tumor growth. Here we report that silencing of HTRA1 in cultured endothelial cells increased migration rate and tube formation, whereas forced HTRA1 expression impaired sprouting angiogenesis. Mechanistically, endothelial HTRA1 expression enhanced Delta/Notch signaling by reducing the amount of the weak Notch ligand JAG1. HTRA1 physically interacted with JAG1 and cleaved it within the intracellular domain, leading to protein degradation. Expression of a constitutive active Notch1 prevented the hypersprouting phenotype upon silencing of HTRA1. In HtrA1-deficient mice, endothelial Notch signaling was diminished and isolated endothelial cells had increased expression of VEGF receptor-2. Growth of syngeneic tumors was strongly impaired in HtrA1^-/- mice. The tumor vasculature was much denser in HtrA1^-/- mice and less covered with mural cells. This chaotic and immature vascular network was poorly functional as indicated by large hypoxic tumor areas and low tumor cell proliferation rates. In summary, inhibition of HTRA1 in the tumor stroma impaired tumor progression by deregulating angiogenesis.

Regulation of Placental Development and Its Impact on Fetal Growth-New Insights From Mouse Models

The placenta is the chief regulator of nutrient supply to the growing embryo during gestation. As such, adequate placental function is instrumental for developmental progression throughout intrauterine development. One of the most common complications during pregnancy is insufficient growth of the fetus, a problem termed intrauterine growth restriction (IUGR) that is most frequently rooted in a malfunctional placenta. Together with conventional gene targeting approaches, recent advances in screening mouse mutants for placental defects, combined with the ability to rapidly induce mutations in vitro and in vivo by CRISPR-Cas9 technology, has provided new insights into the contribution of the genome to normal placental development. Most importantly, these data have demonstrated that far more genes are required for normal placentation than previously appreciated. Here, we provide a summary of common types of placental defects in established mouse mutants, which will help us gain a better understanding of the genes impacting on human placentation. Based on a recent mouse mutant screen, we then provide examples on how these data can be mined to identify novel molecular hubs that may be critical for placental development. Given the close association between placental defects and abnormal cardiovascular and brain development, these functional nodes may also shed light onto the etiology of birth defects that co-occur with placental malformations. Taken together, recent insights into the regulation of mouse placental development have opened up new avenues for research that will promote the study of human pregnancy conditions, notably those based on defects in placentation that underlie the most common pregnancy pathologies such as IUGR and pre-eclampsia.

New Models of Pregnancy-Associated Hypertension

Pregnancy-associated hypertensive disorders are leading causes of maternal and fetal mortality. These include: pre-pregnancy hypertension that persists throughout gestation (chronic/preexisting hypertension), de novo hypertension that is diagnosed after 20 weeks of gestation and resolves after birth (gestational hypertension), de novo hypertension that is diagnosed after 20 weeks of gestation with or without proteinuria and end-organ damage (preeclampsia and eclampsia), and chronic hypertension with superimposed preeclampsia during gestation. Preeclampsia is the most severe form of these disorders. Animal models have been developed by employing surgical, genetic, and pharmacological approaches in order to recapitulate the maternal symptoms of preeclampsia and other hypertensive disorders of pregnancy. The scope of this brief review is to present an up-to-date synthesis of our knowledge of experimental models of pregnancy-associated hypertensive disorders. Novel models, defined in this review as characterized within the last 5 years, will be described and critically discussed. In this review, we will also discuss established experimental models of pregnancy-associated hypertensive disorders in the context of their contribution to new advances in our knowledge about the pathophysiology of these disorders and potential therapeutics. Emphasis will be placed on animal models of preeclampsia; however, models of other hypertensive disorders in pregnancy will also be reviewed.

Role of HTRA1 in bone formation and regeneration: In vitro and in vivo evaluation

The role of mammalian high temperature requirement protease A1 (HTRA1) in somatic stem cell differentiation and mineralized matrix formation remains controversial, having been demonstrated to impart either anti- or pro-osteogenic effects, depending on the in vitro cell model used. The aim of this study was therefore to further evaluate the role of HTRA1 in regulating the differentiation potential and lineage commitment of murine mesenchymal stem cells in vitro, and to assess its influence on bone structure and regeneration in vivo. Our results demonstrated that short hairpin RNA-mediated ablation of Htra1 in the murine mesenchymal cell line C3H10T1/2 increased the expression of several osteogenic gene markers, and significantly enhanced matrix mineralization in response to BMP-2 stimulation. These effects were concomitant with decreases in the expression of chondrogenic gene markers, and increases in adipogenic gene expression and lipid accrual. Despite the profound effects of loss-of-function of HTRA1 on this in vitro osteochondral model, these were not reproduced in vivo, where bone microarchitecture and regeneration in 16-week-old Htra1-knockout mice remained unaltered as compared to wild-type controls. By comparison, analysis of femurs from 52-week-old mice revealed that bone structure was better preserved in Htra1-knockout mice than age-matched wild-type controls. These findings therefore provide additional insights into the role played by HTRA1 in regulating mesenchymal stem cell differentiation, and offer opportunities for improving our understanding of how this multifunctional protease may act to influence bone quality.

Maternal HtrA3 optimizes placental development to influence offspring birth weight and subsequent white fat gain in adulthood

High temperature requirement factor A3 (HtrA3), a member of the HtrA protease family, is highly expressed in the developing placenta, including the maternal decidual cells in both mice and humans. In this study we deleted the HtrA3 gene in the mouse and crossed females carrying zero, one, or two HtrA3-expressing alleles with HtrA3^+/− males to investigate the role of maternal vs fetal HtrA3 in placentation. Although HtrA3^−/− mice were phenotypically normal and fertile, HtrA3 deletion in the mother resulted in intra-uterine growth restriction (IUGR). Disorganization of labyrinthine fetal capillaries was the major placental defect when HtrA3 was absent. The IUGR caused by maternal HtrA3 deletion, albeit being mild, significantly altered offspring growth trajectory long after birth. By 8 months of age, mice born to HtrA3-deficient mothers, independent of their own genotype, were significantly heavier and contained a larger mass of white fat. We further demonstrated that in women serum levels of HtrA3 during early pregnancy were significantly lower in IUGR pregnancies, establishing an association between lower HtrA3 levels and placental insufficiency in the human. This study thus revealed the importance of maternal HtrA3 in optimizing placental development and its long-term impact on the offspring well beyond in utero growth.

Roles of exosomes in the normal and diseased eye

Exosomes are nanometer-sized vesicles that are released by cells in a controlled fashion and mediate a plethora of extra- and intercellular activities. Some key functions of exosomes include cell-cell communication, immune modulation, extracellular matrix turnover, stem cell division/differentiation, neovascularization and cellular waste removal. While much is known about their role in cancer, exosome function in the many specialized tissues of the eye is just beginning to undergo rigorous study. Here we review current knowledge of exosome function in the visual system in the context of larger bodies of data from other fields, in both health and disease. Additionally, we discuss recent advances in the exosome field including use of exosomes as a therapeutic vehicle, exosomes as a source of biomarkers for disease, plus current standards for isolation and validation of exosome populations. Finally, we use this foundational information about exosomes in the eye as a platform to identify areas of opportunity for future research studies.

Transcriptome profile of the human placenta

The human placenta is a particular organ that inseparably binds the mother and the fetus. The proper development and survival of the conceptus relies on the essential interplay between maternal and fetal factors involved in cooperation within the placenta. In our study, high-throughput sequencing (RNA-seq) was applied to analyze the global transcriptome of the human placenta during uncomplicated pregnancies. The RNA-seq was utilized to identify the global pattern of the gene expression in placentas (N = 4) from women in single and twin pregnancies. During analyses, we obtained 228,044 transcripts. More than 91% of them were multi-exon, and among them 134 were potentially unknown protein coding genes. Expression levels (FPKM) were estimated for 38,948 transcriptional active regions, and more than 3000 of genes were expressed with FPKM >20 in each sample. Additionally, all unannotated transcripts with estimated FPKM values were localized on the human genome. Highly covered splice junctions unannotated in the human genome (6497) were identified, and among them 30 were novel. To gain a better understanding of the biological implications, the assembled transcripts were annotated with gene ontology (GO) terms. Single nucleotide variants were predicted for the transcripts assigned to each analyzed GO category. Our results may be useful for establishing a general pattern of the gene expression in the human placenta. Characterizing placental transcriptome, which is crucial for a pregnancy’s outcome, can serve as a basis for identifying the mechanisms underlying physiological pregnancy, as well as may be useful for an early detection of the genomic defects.

Inventory of Novel Animal Models Addressing Etiology of Preeclampsia in the Development of New Therapeutic/Intervention Opportunities

Preeclampsia is a pregnancy-related disease afflicting 3-7% of pregnancies worldwide and leads to maternal and infant morbidity and mortality. The disease is of placental origin and is commonly described as a disease of two stages. A variety of preeclampsia animal models have been proposed, but all of them have limitations in fully recapitulating the human disease. Based on the research question at hand, different or multiple models might be suitable. Multiple animal models in combination with in vitro or ex vivo studies on human placenta together offer a synergistic platform to further our understanding of the etiology of preeclampsia and potential therapeutic interventions. The described animal models of preeclampsia divide into four categories (i) spontaneous, (ii) surgically induced, (iii) pharmacologically/substance induced, and (iv) transgenic. This review aims at providing an inventory of novel models addressing etiology of the disease and or therapeutic/intervention opportunities.