A double-hit pre-eclampsia model results in sex-specific growth restriction patterns

Fetal growth restriction induced by maternal gal-3 deficiency is associated with altered gut-placenta axis

Adverse intrauterine conditions may cause fetal growth restriction (FGR), a pregnancy complication frequently linked to perinatal morbidity and mortality. Although many studies have focused on FGR, the pathophysiological processes underlying this disorder are complex and incompletely understood. We have recently determined that galectin-3 (gal-3), a β-galactoside-binding protein, regulates pregnancy-associated processes, including uterine receptibility, maternal vascular adaptation and placentation. Because gal-3 is expressed at both sides of the maternal-fetal interface, we unraveled the contribution of maternal- and paternal-derived gal-3 on fetal-placental development in the prenatal window and its effects on the post-natal period. Deficiency of maternal gal-3 induced maternal gut microbiome dysbiosis, resulting in a sex-specific fetal growth restriction mainly observed in female fetuses and offspring. In addition, poor placental metabolic adaptions (characterized by decreased trophoblast glycogen content and insulin-like growth factor 2 (Igf2) gene hypomethylation) were only associated with a lack of maternal-derived gal-3. Paternal gal-3 deficiency caused compromised vascularization in the placental labyrinth without affecting fetal growth trajectory. Thus, maternal-derived gal-3 may play a key role in fetal-placental development through the gut-placenta axis.

Overexpression of Human sFLT1 in the Spongiotrophoblast Is Sufficient to Induce Placental Dysfunction and Fetal Growth Restriction in Transgenic Mice

Preeclampsia (PE) is characterized by maternal hypertension and placental dysfunction, often leading to fetal growth restriction (FGR). It is associated with an overexpression of the anti-angiogenic sFLT1 protein, which originates from the placenta and serves as a clinical biomarker to predict PE. To analyze the impact of sFLT1 on placental function and fetal growth, we generated transgenic mice with placenta-specific human sFLT1 (hsFLT1) overexpression. Immunohistochemical, morphometrical, and molecular analyses of the placentas on 14.5 dpc and 18.5 dpc were performed with a focus on angiogenesis, nutrient transport, and inflammation. Additionally, fetal development upon placental hsFLT1 overexpression was investigated. Dams exhibited a mild increase in serum hsFLT1 levels upon placental hsFLT1 expression and revealed growth restriction of the fetuses in a sex-specific manner. Male FGR fetuses expressed higher amounts of placental hsFLT1 mRNA compared to females. FGR placentas displayed an altered morphology, hallmarked by an increase in the spongiotrophoblast layer and changes in labyrinthine vascularization. Further, FGR placentas showed a significant reduction in placental glycogen storage and nutrient transporter expression. Moreover, signs of hypoxia and inflammation were observed in FGR placentas. The transgenic spongiotrophoblast-specific hsFLT1 mouse line demonstrates that low hsFLT1 serum levels are sufficient to induce significant alterations in fetal and placental development in a sex-specific manner.

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.

Preeclampsia promotes autism in offspring via maternal inflammation and fetal NFκB signaling

Preeclampsia (PE) is a risk factor for autism spectrum disorder (ASD) in offspring. However, the exact mechanisms underlying the impact of PE on progeny ASD are not fully understood, which hinders the development of effective therapeutic approaches. This study shows the offspring born to a PE mouse model treated by Nω-nitro-L-arginine methyl ester (L-NAME) exhibit ASD-like phenotypes, including neurodevelopment deficiency and behavioral abnormalities. Transcriptomic analysis of the embryonic cortex and adult offspring hippocampus suggested the expression of ASD-related genes was dramatically changed. Furthermore, the level of inflammatory cytokines TNFα in maternal serum and nuclear factor kappa B (NFκB) signaling in the fetal cortex were elevated. Importantly, TNFα neutralization during pregnancy enabled to ameliorate ASD-like phenotypes and restore the NFκB activation level in the offspring exposed to PE. Furthermore, TNFα/NFκB signaling axis, but not L-NAME, caused deficits in neuroprogenitor cell proliferation and synaptic development. These experiments demonstrate that offspring exposed to PE phenocopies ASD signatures reported in humans and indicate therapeutic targeting of TNFα decreases the likelihood of bearing children with ASD phenotypes from PE mothers.

Growth-Restricted Fetuses and Offspring Reveal Adverse Sex-Specific Metabolic Responses in Preeclamptic Mice Expressing Human sFLT1

Fetal adaptations to harmful intrauterine environments due to pregnancy disorders such as preeclampsia (PE) can negatively program the offspring's metabolism, resulting in long-term metabolic changes. PE is characterized by increased circulating levels of sFLT1, placental dysfunction and fetal growth restriction (FGR). Here we examine the consequences of systemic human sFLT1 overexpression in transgenic PE/FGR mice on the offspring's metabolic phenotype. Histological and molecular analyses of fetal and offspring livers as well as examinations of offspring serum hormones were performed. At 18.5 dpc, sFLT1 overexpression resulted in growth-restricted fetuses with a reduced liver weight, combined with reduced hepatic glycogen storage and histological signs of hemorrhages and hepatocyte apoptosis. This was further associated with altered gene expression of the molecules involved in fatty acid and glucose/glycogen metabolism. In most analyzed features males were more affected than females. The postnatal follow-up revealed an increased weight gain of male PE offspring, and increased serum levels of Insulin and Leptin. This was associated with changes in hepatic gene expression regulating fatty acid and glucose metabolism in male PE offspring. To conclude, our results indicate that sFLT1-related PE/FGR in mice leads to altered fetal liver development, which might result in an adverse metabolic pre-programming of the offspring, specifically targeting males. This could be linked to the known sex differences seen in PE pregnancies in human.

Preeclampsia-induced alterations in brain and liver gene expression and DNA methylation patterns in fetal mice

Exposure to pregnancy complications, including preeclampsia (PE), has lifelong influences on offspring's health. We have previously reported that experimental PE, induced in mice by administration of adenoviral sFlt1 at gestational day 8.5 combined with LPS at day 10.5, results in symmetrical growth restriction in female and asymmetrical growth restriction in male offspring. Here, we characterize the molecular phenotype of the fetal brain and liver with respect to gene transcription and DNA methylation at the end of gestation.In fetal brain and liver, expression and DNA methylation of several key regulatory genes is altered by PE exposure, mostly independent of fetal sex. These alterations point toward a decreased gluconeogenesis in the liver and stimulated neurogenesis in the brain, potentially affecting long-term brain and liver function. The observed sex-specific growth restriction pattern is not reflected in the molecular data, showing that PE, rather than tissue growth, drives the molecular phenotype of PE-exposed offspring.

Impact of inflammation and infection on the expression of amino acid transporters in the placenta: A minireview

Amino acid transporters expressed in the placenta help to regulate the transfer of amino acids from maternal to fetal circulation. Nutritional or hormonal factors are known to potentially impact the expression of amino acid transporters in the placenta. A relatively new field of inquiry has also demonstrated that inflammation, whether associated with infection or not, also alters the expression of amino acid transporters in the placenta. Indeed, studies over the past 15 years have demonstrated that malaria, viral and bacterial models of infection, preeclampsia, and direct administration of proinflammatory cytokines can alter placental amino acid transporter expression. While such studies have largely focused on System A and System L transporters, other transporters are also affected. p38 MAPK, STAT3, mTORC1, and AMPK signaling have all been implicated in these changes, but the underlying mechanism(s) remain to be fully elucidated. Furthermore, the implications of such changes warrant further investigation. This review will summarize studies that have investigated the impact of inflammation on placental amino acid transporter expression, identify questions that remain unanswered, and propose future areas of research to advance the field. As amino acid transporters are now being considered for drug targeting and drug delivery, furthering our understanding of the regulation of these transporters during disease states will be of increasing clinical value. Significance Statement While this is a relatively new field of research, multiple studies have demonstrated that inflammation alters placental amino acid transporter expression. This review will serve to summarize, for the first time, studies in this field and identify gaps in current knowledge as research in this area moves beyond identifying changes in transporter expression to investigating the implications of such changes and the mechanisms underlying them.

MicroRNA-495 suppresses pre-eclampsia via activation of p53/PUMA axis

Linkage between microRNAs (miRNAs) and pre-eclampsia (PE) has been documented. Here, we focused on miR-495 in PE and its underlying mechanism in regulation of trophoblast cells. Expression of miR-495, HDAC2, p53 and PUMA was determined in collected placental tissue samples. Loss- and gain-function was performed to determine the roles of miR-495, HDAC2, p53, and PUMA in biological processes of HTR8/SVneo cells and primary trophoblast cells. The relationships among miR-495, HDAC2, and p53 were pinpointed. PE patients presented with higher expression of miR-495, p53, and PUMA in placental tissues, but lower HDAC2. miR-495 negatively targeted HDAC2 expression. HDAC2 suppressed p53 expression via deacetylation. Overexpression of miR-495, p53, or PUMA inhibited biological properties of HTR8/SVneo cells and primary trophoblast cells, while opposite trends were observed in response to oe-HDAC2. In conclusion, miR-495 knockdown can suppress p53/PUMA axis by targeting HDAC2 to enhance biological behaviors of trophoblast cells, which may prevent occurrence of PE.

Association of sFlt-1 and C-reactive protein with outcomes in severe preeclampsia: A cohort study

ABSTRACT

To determine the association between soluble FMS-like tyrosine kinase-1 (sFlt-1) and high-sensitivity C-reactive protein (hs-CRP) with maternal and perinatal outcomes in patients with preeclampsia (PE) with severe features.A cohort study was conducted on 100 patients, 60 with PE with severe features, and 40 healthy women in the third trimester of pregnancy. Admission serum levels of sFlt-1 and hs-CRP and clinical and epidemiological parameters were evaluated to quantify the predictive ability of adverse maternal and perinatal outcomes using hierarchical multiple regression and receiver operating characteristic curves.Compared to controls, patients with PE and severe features had significantly higher levels of sFlt-1 but not hs-CRP. sFlt-1 and hs-CRP proved to be reasonable parameters for the prediction of composite adverse maternal outcomes. However, we found no correlation between these 2 biomarkers. PE integrated estimate of risk scores were correlated only with sFlt-1 levels. Regarding fetal outcomes, unlike hs-CRP, sFlt-1 was strongly associated with birth weight and Apgar score < 7 at 5 minutes. Following multivariate analysis, maternal age, previous hypertension, sFlt-1, and hs-CRP levels remained independently associated with composite adverse maternal outcomes.sFlt-1 levels were elevated in patients with PE and severe features. Both sFlt-1 and hs-CRP may predict composite adverse maternal outcomes but do not correlate with each other and differ in perinatal morbidity patterns. These data support the hypothesis that the varied outcomes in PE may result from different pathogenic pathways.

Maternal hypertensive disorders in pregnancy and early childhood cardiometabolic risk factors: The Generation R Study

The objective of this study was to determine the associations between hypertensive disorders of pregnancy and early childhood cardiometabolic risk factors in the offspring. Therefore, 7794 women from the Generation Rotterdam Study were included, an ongoing population-based prospective birth cohort. Women with a hypertensive disorder of pregnancy were classified as such when they were affected by pregnancy induced hypertension, pre-eclampsia or the haemolysis, elevated liver enzymes and low platelet count (HELLP) syndrome during pregnancy. Early childhood cardiometabolic risk factors were defined as the body mass index at the age of 2, 6, 12, 36 months and 6 years. Additionally, it included systolic blood pressure, diastolic blood pressure, total fat mass, cholesterol, triglycerides, insulin and clustering of cardiometabolic risk factors at 6 years of age. Sex-specific differences in the associations between hypertensive disorders and early childhood cardiometabolic risk factors were investigated. Maternal hypertensive disorders of pregnancy were inversely associated with childhood body mass index at 12 months (confounder model: -0.15 SD, 95% CI -0.27; -0.03) and childhood triglyceride at 6 years of age (confounder model: -0.28 SD, 95% CI -0.45; -0.10). For the association with triglycerides, this was only present in girls. Maternal hypertensive disorders of pregnancy were not associated with childhood body mass index at 2, 6 and 36 months. No associations were observed between maternal hypertensive disorders of pregnancy and systolic blood pressure, diastolic blood pressure, body mass index, fat mass index and cholesterol levels at 6 years of age. Our findings do not support an independent and consistent association between maternal hypertensive disorders of pregnancy and early childhood cardiometabolic risk factors in their offspring. However, this does not rule out possible longer term effects of maternal hypertensive disorders of pregnancy on offspring cardiometabolic health.

The Placenta's Role in Sexually Dimorphic Fetal Growth Strategies

Fetal sex affects the risk of pregnancy complications and the long-term effects of prenatal environment on health. Some have hypothesized that growth strategies differ between the sexes, whereby males prioritize growth whereas females are more responsive to their environment. This review evaluates the role of the placenta in such strategies, focusing on (1) mechanisms underlying sexual dimorphism in gene expression, (2) the nature and extent of sexual dimorphism in placental gene expression, (3) sexually dimorphic responses to nutrient supply, and (4) sexual dimorphism in morphology and histopathology. The sex chromosomes contribute to sex differences in placental gene expression, and fetal hormones may play a role later in development. Sexually dimorphic placental gene expression may contribute to differences in the prevalence of complications such as preeclampsia, although this link is not clear. Placental responses to nutrient supply frequently show sexual dimorphism, but there is no consistent pattern where one sex is more responsive. There are sex differences in the prevalence of placental histopathologies, and placental changes in pregnancy complications, but also many similarities. Overall, no clear patterns support the hypothesis that females are more responsive to the maternal environment, or that males prioritize growth. While male fetuses are at greater risk of a variety of complications, total prenatal mortality is higher in females, such that males exposed to early insults may be more likely to survive and be observed in studies of adverse outcomes. Going forward, robust statistical approaches to test for sex-dependent effects must be more widely adopted to reduce the incidence of spurious results.

Circulating Maternal sFLT1 (Soluble fms-Like Tyrosine Kinase-1) Is Sufficient to Impair Spiral Arterial Remodeling in a Preeclampsia Mouse Model

Supplemental Digital Content is available in the text.

One driving factor for developing preeclampsia—a pregnancy disorder, often associated with poor spiral artery (SpA)-remodeling and fetal growth restriction—is the anti-angiogenic sFLT1 (soluble fms-like tyrosine kinase-1), which is found to be highly upregulated in preeclampsia patients. The sFLT1-mediated endothelial dysfunction is a common theory for the manifestation of maternal preeclampsia symptoms. However, the influence of sFLT1 on SpA-remodeling and the link between placental and maternal preeclampsia symptoms is less understood. To dissect the hsFLT1 (human sFLT1) effects on maternal and/or fetoplacental physiology in preeclampsia, sFLT1-transgenic mice with systemic hsFLT1 overexpression from midgestation onwards were used. SpA-remodeling was analyzed on histological and molecular level in placental/mesometrial triangle tissues. Maternal kidney and aorta morphology was investigated, combined with blood pressure measurements via telemetry. hsFLT1 overexpression resulted in maternal hypertension, aortic wall thickening, and elastin breakdown. Furthermore, maternal kidneys showed glomerular endotheliosis, podocyte damage, and proteinuria. preeclampsia symptoms were combined with fetal growth restriction already at the end of the second trimester and SpA-remodeling was strongly impaired as shown by persisted vascular smooth muscle cells. This phenotype was associated with shallow trophoblast invasion, delayed presence of uterine natural killer cells, and altered lymphatic angiogenesis. Overall, this study showed that circulating maternal hsFLT1 is sufficient to induce typical maternal preeclampsia-like symptoms in mice and impair the SpA-remodeling independent from the fetoplacental compartment, revealing new insights into the interaction between the placental and maternal contribution of preeclampsia.

Disruption of paternal circadian rhythm affects metabolic health in male offspring via nongerm cell factors

Circadian rhythm synchronizes each body function with the environment and regulates physiology. Disruption of normal circadian rhythm alters organismal physiology and increases disease risk. Recent epidemiological data and studies in model organisms have shown that maternal circadian disruption is important for offspring health and adult phenotypes. Less is known about the role of paternal circadian rhythm for offspring health. Here, we disrupted circadian rhythm in male mice by night-restricted feeding and showed that paternal circadian disruption at conception is important for offspring feeding behavior, metabolic health, and oscillatory transcription. Mechanistically, our data suggest that the effect of paternal circadian disruption is not transferred to the offspring via the germ cells but initiated by corticosterone-based parental communication at conception and programmed during in utero development through a state of fetal growth restriction. These findings indicate paternal circadian health at conception as a newly identified determinant of offspring phenotypes.

Global metabolomic profiling reveals hepatic biosignatures that reflect the unique metabolic needs of late-term mother and fetus

OBJECTIVE

Gestational disorders including preeclampsia, growth restriction and diabetes are characterized, in part, by altered metabolic interactions between mother and fetus. Understanding their functional relevance requires metabolic characterization under normotypic conditions.

METHODS

We performed untargeted metabolomics on livers of pregnant, late-term C57Bl/6J mice (N = 9 dams) and their fetuses (pooling 4 fetuses/litter), using UPLC-MS/MS.

RESULTS

Multivariate analysis of 730 hepatic metabolites revealed that maternal and fetal metabolite profiles were highly compartmentalized, and were significantly more similar within fetuses (ρ_average = 0.81), or within dams (ρ_average = 0.79), than within each maternal-fetal dyad (ρ_average = - 0.76), suggesting that fetal hepatic metabolism is under distinct and equally tight metabolic control compared with its respective dam. The metabolite profiles were consistent with known differences in maternal-fetal metabolism. The reduced fetal glucose reflected its limited capacity for gluconeogenesis and dependence upon maternal plasma glucose pools. The fetal decreases in essential amino acids and elevations in their alpha-keto acid carnitine conjugates reflects their importance as secondary fuel sources to meet fetal energy demands. Whereas, contrasting elevations in fetal serine, glycine, aspartate, and glutamate reflects their contributions to endogenous nucleotide synthesis and fetal growth. Finally, the elevated maternal hepatic lipids and glycerol were consistent with a catabolic state that spares glucose to meet competing maternal-fetal energy demands.

CONCLUSIONS

The metabolite profile of the late-term mouse dam and fetus is consistent with prior, non-rodent analyses utilizing plasma and urine. These data position mouse as a suitable model for mechanistic investigation into how maternal-fetal metabolism adapts (or not) to gestational stressors.

Altered offspring neurodevelopment in an arginine vasopressin preeclampsia model

Preeclampsia is a severe gestational hypertensive condition linked to child neuropsychiatric disorders, although underlying mechanisms are unclear. We used a recently developed, clinically relevant animal model of preeclampsia to assess offspring. C57BL/6J mouse dams were chronically infused with arginine vasopressin (AVP) or saline (24 ng/h) throughout pregnancy. Adult offspring were behaviorally tested (Y-maze, open field, rotarod, social approach, and elevated plus maze). Offspring brain was assessed histologically and by RNA sequencing. Preeclampsia-exposed adult males exhibited increased anxiety-like behavior and social approach while adult females exhibited impaired procedural learning. Adult AVP-exposed males had reduced total neocortical volume. Adult AVP-exposed females had increased caudate-putamen volume, increased caudate-putamen cell number, and decreased excitatory synapse density in hippocampal dentate gyrus (DG), CA1, and CA3. At postnatal day 7 (P7), AVP-exposed male and female offspring both had smaller neocortex. At P7, AVP-exposed males also had smaller caudate-putamen volume, while females had increased caudate-putamen volume relative to neocortical size. Similar to P7, E18 AVP-exposed offspring had smaller dorsal forebrain, mainly in reduced intermediate, subventricular, and ventricular zone volume, particularly in males. Decreased volume was not accounted for by cell size or cerebrovascular vessel diameter changes. E18 cortical RNAseq revealed 49 differentially-expressed genes in male AVP-exposed offspring, over-representing cytoplasmic translation processes. In females, 31 genes were differentially-expressed, over-representing collagen-related and epithelial regulation pathways. Gene expression changes in E18 AVP-exposed placenta indicated potential underlying mechanisms. Deficits in behavior and forebrain development in this AVP-based preeclampsia model were distinctly different in males and females, implicating different neurobiological bases.

Plasma Lipid Profile and Intestinal Microflora in Pregnancy Women With Hypothyroidism and Their Correlation With Pregnancy Outcomes

OBJECTIVE

To investigate the lipid profiles and intestinal microflora in pregnant patients with hypothyroidism and their correlation with pregnancy outcomes.

METHODS

In total, 27 pregnant women with hypothyroidism (study case) and 28 normal pregnant women (control group) were enrolled in this study. The lipid profiles and intestinal microflora in the two groups were compared using untargeted liquid chromatography-mass spectrometry (LC-MS) and 16S rRNA amplicon sequencing, respectively. The association among the differential metabolites, intestinal microflora, serological indicators and pregnancy outcomes was further analyzed.

RESULTS

Patients in study case had higher C-reactive protein (CRP) levels (P = 0.025) and lower birth weight (P=0.005) than the control group. A total of 42 differential lipid metabolites and 7 enrichment KEGG pathways were obtained between the two groups (VIP ≥ 1, P < 0.05). Ten lipid metabolites can be used as characteristic metabolites of study case, including phosphatidylcholine (PC), phosphatidylethanolamine (PE) and sphingomyelin (SM). The richness and diversity of intestinal microflora in study case were lower than those in the control group (P>0.05). LEfSe analysis revealed that patients in study case had higher abundance of Prevotella and Haemophilus and lower abundance of Blautia than the control group (P < 0.05). Blautia was positively correlated with SM and negatively correlated with PC and PE; the CRP level and Prevotella were positively correlated; the neonatal weight and PC level were negatively correlated (P < 0.05).

CONCLUSION

The lipid profile and intestinal microflora of pregnant women with hypothyroidism significantly differed from those of normal pregnant women and were associated with adverse pregnancy outcomes. The interaction between lipid metabolism and intestinal microflora may be a potential target for further studies investigating the pathogenesis of hypothyroidism during pregnancy.

Mid-gestation low-dose LPS administration results in female-specific excessive weight gain upon a western style diet in mouse offspring

Gestational complications, including preeclampsia and gestational diabetes, have long-term adverse consequences for offspring's metabolic and cardiovascular health. A low-grade systemic inflammatory response is likely mediating this. Here, we examine the consequences of LPS-induced gestational inflammation on offspring's health in adulthood. LPS was administered to pregnant C57Bl/6J mice on gestational day 10.5. Maternal plasma metabolomics showed oxidative stress, remaining for at least 5 days after LPS administration, likely mediating the consequences for the offspring. From weaning on, all offspring was fed a control diet; from 12 to 24 weeks of age, half of the offspring received a western-style diet (WSD). The combination of LPS-exposure and WSD resulted in hyperphagia and increased body weight and body fat mass in the female offspring. This was accompanied by changes in glucose tolerance, leptin and insulin levels and gene expression in liver and adipose tissue. In the hypothalamus, expression of genes involved in food intake regulation was slightly changed. We speculate that altered food intake behaviour is a result of dysregulation of hypothalamic signalling. Our results add to understanding of how maternal inflammation can mediate long-term health consequences for the offspring. This is relevant to many gestational complications with a pro-inflammatory reaction in place.

Animal Models of Preeclampsia: Causes, Consequences, and Interventions

Preeclampsia is a common pregnancy complication, affecting 2% to 8% of pregnancies worldwide, and is an important cause of both maternal and fetal morbidity and mortality. Importantly, although aspirin and calcium are able to prevent preeclampsia in some women, there is no cure apart from delivery of the placenta and fetus, often necessitating iatrogenic preterm birth. Preclinical models of preeclampsia are widely used to investigate the causes and consequences of preeclampsia and to evaluate safety and efficacy of potential preventative and therapeutic interventions. In this review, we provide a summary of the published preclinical models of preeclampsia that meet human diagnostic criteria, including the development of maternal hypertension, together with new-onset proteinuria, maternal organ dysfunction, and uteroplacental dysfunction. We then discuss evidence from preclinical models for multiple causal factors of preeclampsia, including those implicated in early-onset and late-onset preeclampsia. Next, we discuss the impact of exposure to a preeclampsia-like environment for later maternal and progeny health. The presence of long-term impairment, particularly cardiovascular outcomes, in mothers and progeny after an experimentally induced preeclampsia-like pregnancy, implies that later onset or reduced severity of preeclampsia will improve later maternal and progeny health. Finally, we summarize published intervention studies in preclinical models and identify gaps in knowledge that we consider should be targets for future research.

Neurodevelopmental Outcomes of Prenatal Preeclampsia Exposure

Preeclampsia is a dangerous hypertensive disorder of pregnancy with known links to negative child health outcomes. Here, we review epidemiological and basic neuroscience work from the past several decades linking prenatal preeclampsia to altered neurodevelopment. This work demonstrates increased rates of neuropsychiatric disorders [e.g., increased autism spectrum disorder, attention deficit hyperactivity disorder (ADHD)] in children of preeclamptic pregnancies, as well as increased rates of cognitive impairments [e.g., decreased intelligence quotient (IQ), academic performance] and neurological disease (e.g., stroke and epilepsy). We also review findings from multiple animal models of preeclampsia. Manipulation of key clinical preeclampsia processes in these models (e.g., placental hypoxia, immune dysfunction, angiogenesis, oxidative stress) causes various disruptions in offspring, including ones in white matter/glia, glucocorticoid receptors, neuroimmune outcomes, cerebrovascular structure, and cognition/behavior. This animal work implicates potentially high-yield targets that may be leveraged in the future for clinical application.

Human sFLT1 Leads to Severe Changes in Placental Differentiation and Vascularization in a Transgenic hsFLT1/rtTA FGR Mouse Model

The anti-angiogenic soluble fms-like tyrosine kinase 1 (sFLT1) is one of the candidates in the progression of preeclampsia, often associated with fetal growth restriction (FGR). Therapeutic agents against preeclampsia with/without FGR, as well as adequate transgenic sFLT1 mouse models for testing such agents, are still missing. Much is known about sFLT1-mediated endothelial dysfunction in several tissues; however, the influence of sFLT1 on placental and fetal development is currently unknown. We hypothesize that sFLT1 is involved in the progression of FGR by influencing placental differentiation and vascularization and is a prime candidate for interventional strategies. Therefore, we generated transgenic inducible human sFLT1/reverse tetracycline-controlled transactivator (hsFLT1/rtTA) mice, in which hsFLT1 is ubiquitously overexpressed during pregnancy in dams and according to the genetics in hsFLT1/rtTA homozygous and heterozygous fetuses. Induction of hsFLT1 led to elevated hsFLT1 levels in the serum of dams and on mRNA level in all placentas and hetero-/homozygous fetuses, resulting in FGR in all fetuses at term. The strongest effects in respect to FGR were observed in the hsFLT1/rtTA homozygous fetuses, which exhibited the highest hsFLT1 levels. Only fetal hsFLT1 expression led to impaired placental morphology characterized by reduced placental efficiency, enlarged maternal sinusoids, reduced fetal capillaries, and impaired labyrinthine differentiation, associated with increased apoptosis. Besides impaired placental vascularization, the expression of several transporter systems, such as glucose transporter 1 and 3 (Glut-1; Glut-3); amino acid transporters, solute carrier family 38, member one and two (Slc38a1; Slc38a2); and most severely the fatty acid translocase Cd36 and fatty acid binding protein 3 (Fabp3) was reduced upon hsFLT1 expression, associated with an accumulation of phospholipids in the maternal serum. Moreover, the Vegf pathway showed alterations, resulting in reduced Vegf, Vegfb, and Plgf protein levels and increased Bad and Caspase 9 mRNA levels. We suggest that hsFLT1 exerts an inhibitory influence on placental vascularization by reducing Vegf signaling, which leads to apoptosis in fetal vessels, impairing placental differentiation, and the nutrient exchange function of the labyrinth. These effects were more pronounced when both the dam and the fetus expressed hsFLT1 and ultimately result in FGR and resemble the preeclamptic phenotype in humans.