Sildenafil Treatment Ameliorates the Maternal Syndrome of Preeclampsia and Rescues Fetal Growth in the Dahl Salt-Sensitive Rat

Protein Misfolding in Pregnancy: Current Insights, Potential Mechanisms, and Implications for the Pathogenesis of Preeclampsia

Protein misfolding disorders are a group of diseases characterized by supra-physiologic accumulation and aggregation of pathogenic proteoforms resulting from improper protein folding and/or insufficiency in clearance mechanisms. Although these processes have been historically linked to neurodegenerative disorders, such as Alzheimer's disease, evidence linking protein misfolding to other pathologies continues to emerge. Indeed, the deposition of toxic protein aggregates in the form of oligomers or large amyloid fibrils has been linked to type 2 diabetes, various types of cancer, and, in more recent years, to preeclampsia, a life-threatening pregnancy-specific disorder. While extensive physiological mechanisms are in place to maintain proteostasis, processes, such as aging, genetic factors, or environmental stress in the form of hypoxia, nutrient deprivation or xenobiotic exposures can induce failure in these systems. As such, pregnancy, a natural physical state that already places the maternal body under significant physiological stress, creates an environment with a lower threshold for aberrant aggregation. In this review, we set out to discuss current evidence of protein misfolding in pregnancy and potential mechanisms supporting a key role for this process in preeclampsia pathogenesis. Improving our understanding of this emerging pathophysiological process in preeclampsia can lead to vital discoveries that can be harnessed to create better diagnoses and treatment modalities for the disorder.

In vivo noninvasive systemic myography of acute systemic vasoactivity in female pregnant mice

Altered vasoactivity is a major characteristic of cardiovascular and oncological diseases, and many therapies are therefore targeted to the vasculature. Therapeutics which are selective for the diseased vasculature are ideal, but whole-body selectivity of a therapeutic is challenging to assess in practice. Vessel myography is used to determine the functional mechanisms and evaluate pharmacological responses of vascularly-targeted therapeutics. However, myography can only be performed on ex vivo sections of individual arteries. We have developed methods for implementation of spherical-view photoacoustic tomography for non-invasive and in vivo myography. Using photoacoustic tomography, we demonstrate the measurement of acute vascular reactivity in the systemic vasculature and the placenta of female pregnant mice in response to two vasodilators. Photoacoustic tomography simultaneously captures the significant acute vasodilation of major arteries and detects selective vasoactivity of the maternal-fetal vasculature. Photoacoustic tomography has the potential to provide invaluable preclinical information on vascular response that cannot be obtained by other established methods.

Novel therapeutic and diagnostic approaches for preeclampsia

PURPOSE OF REVIEW

This review will summarize recent findings relating to the diagnostic approach to preeclampsia and current avenues of research aimed at modifying the underlying disease process.

RECENT FINDINGS

Growing international consensus supports a broad preeclampsia definition that incorporates maternal end-organ and uteroplacental dysfunction. Recent evidence demonstrates that this definition better identifies women and babies at risk of adverse outcomes compared to the traditional definition of hypertension and proteinuria. Multiple studies have demonstrated the usefulness and cost-effectiveness of angiogenic biomarkers such as soluble fms-like tyrosine kinase-1 and placental growth factor as a clinical adjunct to diagnose and predict severity of preeclampsia associated outcomes. Current novel therapeutic approaches to preeclampsia target pathogenic pathways (e.g. antiangiogenesis) or downstream effects such as oxidative stress and nitric oxide. Recent findings relating to these promising candidates are discussed. Multicenter clinical trials are needed to evaluate their effectiveness and ability to improve fetal and maternal outcomes.

SUMMARY

We provide an updated framework of the current approaches to define and diagnose preeclampsia. Disease modifying therapies (in particular, targeting the angiogenic pathway) are being developed for the first time and promise to revolutionize the way we manage preeclampsia.

Hydroxychloroquine reduces hypertension and soluble fms-like kinase-1 in a Nω-nitro-l-arginine methyl ester-induced preeclampsia rat model

OBJECTIVE

Hydroxychloroquine, a drug used for malaria and autoimmune diseases reportedly has beneficial effects against preeclampsia in pregnant women with lupus. However, its mechanism against preeclampsia remains unclear. We investigated the effect of hydroxychloroquine on an Nω-nitro-l-arginine methyl ester-induced preeclampsia rat model.

METHODS

Pregnant Sprague-Dawley rats were divided into four groups based on treatment (administered on gestational days 7-18): control, Nω-nitro-l-arginine methyl ester, hydroxychloroquine, and Nω-nitro-l-arginine methyl ester plus hydroxychloroquine. All animals were sacrificed on gestational day 19. We assayed tube formation and determined reactive oxygen species levels using human umbilical vein endothelial cells.

RESULTS

Results showed that hydroxychloroquine significantly lowered mean systolic blood pressure (P  < 0.05) in Nω-nitro-l-arginine methyl ester-treated rats. Hydroxychloroquine did not affect their fetal and placental weights. Hydroxychloroquine mitigated Nω-nitro-l-arginine methyl ester-associated changes in proteinuria (P  < 0.05). It normalized plasma soluble fms-like kinase-1 (P  < 0.05) and endothelin-1 (P  < 0.01) levels. In the tube formation assay, hydroxychloroquine increased the total meshes area (P  < 0.05) and mitigated Nω-nitro-l-arginine methyl ester-induced reactive oxygen species formation (P  < 0.05) in human umbilical vein endothelial cells.

CONCLUSION

We conclude that hydroxychloroquine alleviated hypertension, proteinuria, and normalized soluble fms-like kinase-1 and endothelin-1 levels in our preeclampsia model and that these changes may involve the restoration of endothelial dysfunction; thus, hydroxychloroquine could potentially be used for preventing preeclampsia, even in the absence of lupus.

Animal Models of Preeclampsia: Mechanistic Insights and Promising Therapeutics

Preeclampsia (PE) is a common pregnancy-specific disorder that is a major cause of both maternal and fetal morbidity and mortality. Central to the pathogenesis of PE is the production of antiangiogenic and inflammatory factors by the hypoxic placenta, leading to the downstream manifestations of the disease, including hypertension and end-organ damage. Currently, effective treatments are limited for PE; however, the development of preclinical animal models has helped in the development and evaluation of new therapeutics. In this review, we will summarize some of the more commonly used models of PE and highlight their similarities to the human syndrome, as well as the therapeutics tested in each model.

Animal Models of Cardiovascular Complications of Pregnancy

Cardiovascular complications of pregnancy have risen substantially over the past decades, and now account for the majority of pregnancy-induced maternal deaths, as well as having substantial long-term consequences on maternal cardiovascular health. The causes and pathophysiology of these complications remain poorly understood, and therapeutic options are limited. Preclinical models represent a crucial tool for understanding human disease. We review here advances made in preclinical models of cardiovascular complications of pregnancy, including preeclampsia and peripartum cardiomyopathy, with a focus on pathological mechanisms elicited by the models and on relevance to human disease.

Periconceptional 1,3-butanediol supplementation suppresses the superimposed preeclampsia-like phenotype in the Dahl salt-sensitive rat

Preeclampsia is a hypertensive pregnancy disorder with no treatment beyond management of symptoms and delivery of the fetus and placenta. Chronic hypertension increases the risk of developing superimposed preeclampsia. Previous reports showed that 1,3-butanediol attenuates hypertension in rodents; however, the therapeutic potential of 1,3-butanediol for the prevention of preeclampsia has not been investigated. This study tested the hypothesis that attenuating hypertension before pregnancy and through the placentation period via 1,3-butanediol prevents the onset of preeclampsia in female Dahl salt-sensitive (SS/Jr) rats. Female Dahl SS/Jr rats were divided into two groups: 1,3-butanediol treated (20% via drinking water) and control (ad libitum water). Both groups were maintained on low-salt rodent chow (Teklad 7034, 0.3% NaCl; n = 8/group). Animals were treated with 1,3-butanediol for 7 wk (baseline), mated, and treated through day 12 of pregnancy. 1,3-Butanediol treatment increased plasma β-hydroxybutyrate (metabolite of 1,3-butanediol) that negatively correlated with maternal body weight in late pregnancy. Mean arterial pressure was lower in the treated group at baseline, early, and mid pregnancy, but no difference was observed in late pregnancy after treatment ended. Uterine artery resistance index (UARI) was reduced in the treated dams. No adverse fetal effects were observed, and there were no differences in pup weight or length. Placentas from treated dams had decreased vascular endothelial growth factor levels as well as decreased placental basal zone thickness and increased labyrinth zone thickness. These findings support the therapeutic role of physiological ketosis via 1,3-butanediol as a potential therapeutic approach for managing chronic hypertension, thereby preventing and mitigating adverse pregnancy outcomes associated with preeclampsia.NEW & NOTEWORTHY A ketogenic diet or increased β-hydroxybutyrate levels can reduce hypertension, but the potential of 1,3-butanediol, a β-hydroxybutyrate precursor, for treatment of preeclampsia is unknown. We hypothesized that attenuating hypertension before and during pregnancy via 1,3-butanediol prevents preeclampsia in Dahl Salt-sensitive rats. 1,3-Butanediol significantly lowered blood pressure and improved uterine artery resistance with no observable adverse fetal effects. Physiological ketosis via 1,3-butanediol may be a potential therapeutic approach for managing hypertension and mitigating adverse pregnancy outcomes.

Animal models of preeclampsia: investigating pathophysiology and therapeutic targets

Animal models have been critical in investigating the pathogenesis, mediators, and even therapeutic options for a number of diseases, including preeclampsia. Preeclampsia is the leading cause of maternal and fetal morbidity and mortality worldwide. The placenta is thought to play a central role in the pathogenesis of this disease because it releases antiangiogenic and proinflammatory factors into the maternal circulation, resulting in the maternal syndrome. Despite the deleterious effects preeclampsia has been shown to have on the mother and baby during pregnancy and postpartum, there is still no effective treatment for this disease. Although clinical studies in patients are crucial to identify the involvement of pathogenic factors in preeclampsia, there are obvious limitations that prevent detailed investigation of the quantitative importance of time-dependent mechanisms involved in this syndrome. Animal models allow investigators to perform proof-of-concept studies and examine whether certain factors found in women with preeclampsia mediate hypertension and other manifestations of this disease. In this brief review, we summarize some of the more widely studied models used to investigate pathophysiological mechanisms that are thought to be involved in preeclampsia. These include models of placental ischemia, angiogenic imbalance, and maternal immune activation. Infusion of preeclampsia-related factors into animals has been widely studied to understand the specific mediators of this disease. These models have been included, in addition to a number of genetic models involved in overexpression of the renin-angiotensin system, complement activation, and trophoblast differentiation. Together, these models cover multiple mechanisms of preeclampsia from trophoblast dysfunction and impaired placental vascularization to the excess circulating placental factors and clinical manifestation of this disease. Most animal studies have been performed in rats and mice; however, we have also incorporated nonhuman primate models in this review. Preclinical animal models not only have been instrumental in understanding the pathophysiology of preeclampsia but also continue to be important tools in the search for novel therapeutic options for the treatment of this disease.

Physiological characterization of an arginine vasopressin rat model of preeclampsia

Rodent models have contributed greatly to our understanding of preeclampsia (PE) progression in humans, however to-date no model has been able to effectively replicate the clinical presentation of the disease. This study aimed to provide a thorough physiological characterization of the arginine vasopressin (AVP)-induced rat model of PE to determine its applicability in studying the pathophysiology of PE. Female Sprague Dawley rats (n = 24) were separated into four groups (n = 6 per group) viz., pregnant AVP, pregnant saline, non-pregnant AVP, and non-pregnant saline. All animals received a continuous dose of either AVP (150 ng/h) or saline via subcutaneous mini osmotic pumps for 18 days. Full physiological characterization of the model included measuring systolic and diastolic blood pressure, and collecting urine and blood samples for biochemical analysis. AVP infusion significantly increased blood pressure and urinary protein levels in the pregnant rats (p < 0.05). Biochemical markers measured, differed significantly in the AVP-treated vs the pregnant saline groups (p < 0.05). Placental and individual pup weight decreased significantly in the pregnant AVP vs pregnant saline group (p < 0.05). The physiological and hematological data confirm the usefulness of this rat model in the study of PE, since AVP-induced vasoconstriction increases peripheral resistance and successfully mimics the pathological changes associated with PE development in humans.Abbreviations: PE: preeclampsia; AVP: arginine vasopressin; ISSHP: International Society for the Study of Hypertension in Pregnancy; ACOG: American College of Obstetricians and Gynecologists; RUPP: reduced uterine perfusion pressure; sFlt-1: soluble fms-like tyrosine kinase; VEGF: vascular endothelial growth factor; PlGF: placental growth factor; AVP: arginine vasopressin; PAVP: pregnant AVP-treated; PS: pregnant saline; GD: gestational day; ALT: alanine transaminase; NAVP: non-pregnant AVP-treated; NS: non-pregnant saline; AST: aspartate aminotransferase; HDL: high-density lipoprotein; RBC: red blood cell; RAAS: renin-angiotensin aldosterone system; HELLP: hemolysis, elevated liver enzymes, low platelet.

Comparison of the Effect of Nifedipine Alone and the Combination of Nifedipine and Sildenafil in Delaying Preterm Labor: A Randomized Clinical Trial

Objective: Recently, sildenafil as a drug effective in relaxing smooth muscles can be used as an adjunct to delay the onset of uterine contractions and therefore the occurrence of preterm labor. The aim of this study was to evaluate the effect of nifedipine combination with sildenafil on preterm delivery compared with nifedipine alone. Materials and methods: This randomized double-blinded clinical trial was performed on pregnant women with a gestational age of 26-34 weeks with singleton pregnancy and symptoms of preterm delivery. The mothers were randomly assigned into two groups receiving nifedipine plus sildenafil or those receiving nifedipine alone. The time of delivery, maternal and neonatal complications were compared between the two groups. Results: Mothers who received the combination therapy experienced significantly lower preterm delivery within 72 hours of intervention compared to nifedipine alone (4.5% versus 27.3%, p = 0.002). The rate of delivery during the first 7 days after discharge was 7.6% and 31.8% in nifedipine plus sildenafil and nifedipine alone, respectively (P = 0.001). The prevalence of neonatal respiratory distress syndrome (RDS) as well as mean birth weight was higher in the nifedipine group alone. Treatment protocol with nifedipine and sildenafil compared with nifedipine alone was associated with a significant increase in preterm delivery delay (beta =-5.819, p = 0.001). Conclusion: The use of sildenafil in addition to nifedipine causes more delay in delivery in cases of preterm labor, followed by lower risk for RDS, reduces neonatal intensive care unit (NICU) admission, and preserves neonatal birth weight.

Placental Ischemia Says "NO" to Proper NOS-Mediated Control of Vascular Tone and Blood Pressure in Preeclampsia

In this review, we first provide a brief overview of the nitric oxide synthase (NOS) isoforms and biochemistry. This is followed by describing what is known about NOS-mediated blood pressure control during normal pregnancy. Circulating nitric oxide (NO) bioavailability has been assessed by measuring its metabolites, nitrite (NO₂) and/or nitrate (NO₃), and shown to rise throughout normal pregnancy in humans and rats and decline postpartum. In contrast, placental malperfusion/ischemia leads to systemic reductions in NO bioavailability leading to maternal endothelial and vascular dysfunction with subsequent development of hypertension in PE. We end this article by describing emergent risk factors for placental malperfusion and ischemic disease and discussing strategies to target the NOS system therapeutically to increase NO bioavailability in preeclamptic patients. Throughout this discussion, we highlight the critical importance that experimental animal studies have played in our current understanding of NOS biology in normal pregnancy and their use in finding novel ways to preserve this signaling pathway to prevent the development, treat symptoms, or reduce the severity of PE.

Immunological comparison of pregnant Dahl salt-sensitive and Sprague-Dawley rats commonly used to model characteristics of preeclampsia

The pregnant Dahl salt-sensitive (S) rat is an established preclinical model of superimposed spontaneous preeclampsia characterized by exacerbated hypertension, increased urinary protein excretion, and increased fetal demise. Because of the underlying immune system dysfunction present in preeclamptic pregnancies in humans, we hypothesized that the pregnant Dahl S rat would also have an altered immune status. Immune system activation was assessed during late pregnancy in the Dahl S model and compared with healthy pregnant Sprague-Dawley (SD) rats subjected to either a sham procedure or a procedure to reduce uterine perfusion pressure (RUPP). Circulating immunoglobulin and cytokine levels were measured by enzyme-linked immunosorbent assay (ELISA) and Milliplex bead assay, respectively, and percentages of circulating, splenic, and placental immune cells were determined using flow cytometry. The pregnant Dahl S rat exhibited an increase in CD4+ T cells, and specifically TNFα+CD4+ T cells, in the spleen compared with virgin Dahl S rats. The Dahl also had increased neutrophils and decreased B cells in the peripheral blood as compared with Dahl virgin rats. SD rats that received the RUPP procedure had increases in circulating monocytes and increased IFN-ɣ+CD4+ splenic T cells. Together these findings suggest that dysregulated T cell activity is an important factor in both the pregnant Dahl S rats and SD rats after the RUPP procedure.

Sildenafil augments fetal weight and placental adiponectin in gestational testosterone-induced glucose intolerant rats

Testosterone induces intra-uterine growth restriction (IUGR) with maternal glucose dysregulation and oxidant release in various tissues. Adiponectin, which modulates the antioxidant nuclear factor erythroid 2-related factor 2 (Nrf2) signaling is expressed in the placenta and affects fetal growth. Sildenafil, a phosphodiesterase type 5 inhibitor (PDE5i), used mainly in erectile dysfunction has been widely studied as a plausible pharmacologic candidate in IUGR. Therefore, the present study sought to determine the effect of PDE5i on placental adiponectin/Nrf2 pathway in gestational testosterone-induced impaired glucose tolerance and fetal growth. Fifteen pregnant Wistar rats were allotted into three groups (n = 5/group) receiving vehicles (Ctr; distilled water and olive oil), testosterone propionate (Tes; 3.0 mg/kg; sc) or combination of testosterone propionate (3.0 mg/kg; sc) and sildenafil (50.0 mg/kg; po) from gestational day 14-19. On gestational day 20, plasma and placenta homogenates were obtained for biochemical analysis as well as fetal biometry. Pregnant rats exposed to testosterone had 4-fold increase in circulating testosterone compared with control (20.9 ± 2.8 vs 5.1 ± 1.7 ng/mL; p < 0.05) whereas placenta testosterone levels were similar in testosterone- and vehicle-treated rats. Exposure to gestational testosterone caused reduction in fetal and placental weights, placental Nrf2 and adiponectin. Moreover, impaired glucose tolerance, elevated plasma triglyceride-glucose (TyG) index, placental triglyceride, total cholesterol, lactate, malondialdehyde and alanine aminotransferase were observed in testosterone-exposed rats. Treatment with sildenafil improved glucose tolerance, plasma TyG index, fetal and placental weights and reversed placental adiponectin in testosterone-exposed pregnant rats without any effect on placental Nrf2. Therefore, in testosterone-exposed rats, sildenafil improves impaired glucose tolerance, poor fetal outcome which is accompanied by augmented placental adiponectin regardless of depressed Nrf2.

Dietary protein source contributes to the risk of developing maternal syndrome in the Dahl salt-sensitive rat

Preeclampsia (PE) is a disorder of pregnancy, which is categorized by hypertension and proteinuria or signs of end-organ damage. Though PE is the leading cause of maternal and fetal morbidity and mortality, the mechanisms leading to PE remain unclear. The present study examined the contribution of dietary protein source (casein versus wheat gluten) to the risk of developing maternal syndrome utilizing two colonies of Dahl salt-sensitive (SS/JrHsdMcwi) rats. While the only difference between the colonies is the diet, the colonies exhibit profound differences in the pregnancy phenotypes. The SS rats maintained on the wheat gluten (SSWG) chow are protected from developing maternal syndrome; however, approximately half of the SS rats fed a casein-based diet (SSC) exhibit maternal syndrome. Those SSC rats that develop pregnancy-specific increases in blood pressure and proteinuria have no observable differences in renal or placental immune profiles compared to the protected SS rats. A gene profile array of placental tissue revealed a downregulation in Nos3 and Cyp26a1 in the SSC rats that develop maternal syndrome accompanied with increases in uterine artery resistance index suggesting the source of this phenotype could be linked to inadequate remodeling within the placenta. Investigations into the effects of multiple pregnancies on maternal health replicated similar findings. The SSC colony displayed an exacerbation in proteinuria, renal hypertrophy and renal immune cell infiltration associated with an increased mortality rate while the SSWG colony were protected highlighting how dietary protein source could have beneficial effects in PE.

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.

Preeclampsia: Linking Placental Ischemia with Maternal Endothelial and Vascular Dysfunction

Preeclampsia (PE), a hypertensive disorder, occurs in 3% to 8% of pregnancies in the United States and affects over 200,000 women and newborns per year. The United States has seen a 25% increase in the incidence of PE, largely owing to increases in risk factors, including obesity and cardiovascular disease. Although the etiology of PE is not clear, it is believed that impaired spiral artery remodeling of the placenta reduces perfusion, leading to placental ischemia. Subsequently, the ischemic placenta releases antiangiogenic and pro-inflammatory factors, such as cytokines, reactive oxygen species, and the angiotensin II type 1 receptor autoantibody (AT1-AA), among others, into the maternal circulation. These factors cause widespread endothelial activation, upregulation of the endothelin system, and vasoconstriction. In turn, these changes affect the function of multiple organ systems including the kidneys, brain, liver, and heart. Despite extensive research into the pathophysiology of PE, the only treatment option remains early delivery of the baby and importantly, the placenta. While premature delivery is effective in ameliorating immediate risk to the mother, mounting evidence suggests that PE increases risk of cardiovascular disease later in life for both mother and baby. Notably, these women are at increased risk of hypertension, heart disease, and stroke, while offspring are at risk of obesity, hypertension, and neurological disease, among other complications, later in life. This article aims to discuss the current understanding of the diagnosis and pathophysiology of PE, as well as associated organ damage, maternal and fetal outcomes, and potential therapeutic avenues. © 2021 American Physiological Society. Compr Physiol 11:1315-1349, 2021.

Adjuvant Vaginal Use of Sildenafil Citrate in a Hormone Replacement Cycle Improved Live Birth Rates Among 10,069 Women During First Frozen Embryo Transfers

Purpose

To investigate the effects of sildenafil citrate (SC) on live birth rates (LBR) during women undergoing their first frozen embryo transfers (FET) with hormone replacement therapy (HRT).

Patients and Methods

This retrospective cohort study included a total of 10,069 infertile women with adequate endometrial thickness (≥7 mm when progesterone was initiated) in their first FET cycle with hormone replacement therapy. Women received either vaginal SC or no adjuvant during their first transfer cycle depending on patient or physician preference. In the sildenafil group, 1098 women underwent HRT FET with adjuvant vaginal use of SC, and 8971 women were included as controls. The primary outcome measure was LBR, defined as the likelihood of live birth per transfer cycle. Endometrial thickness (EMT), implantation, chemical pregnancy, clinical pregnancy, miscarriage, ongoing pregnancy, birth weight and preterm delivery (PTB) were also recorded.

Results

Baseline characteristics were comparable between the two groups. In the crude analysis, the unadjusted LBR was significantly higher in the vaginal SC group (scHRT-FET) than in the control group (HRT-FET) (40.3% vs 36.1%). After adjustment for 12 pregnancy-related confounding factors, logistic regression analysis showed that LBR remained significantly higher in the scHRT-FET group than in the HRT-FET group (adjusted odds ratio [aOR] 1.31, 95% confidence interval [CI] 1.14–1.49). Furthermore, after adjustment, the ongoing pregnancy rate was significantly higher (aOR 1.29, 95% CI 1.13–1.47), and the miscarriage rate was significantly lower (aOR 0.58, 95% CI 0.43–0.77), in the scHRT-FET group compared to the HRT-FET group. Adjuvant vaginal use of SC did not increase the endometrial thickness and had no significant effect on birth weight or PTB.

Conclusion

Adjuvant vaginal use of SC in HRT FET was associated with higher LBR and improved pregnancy outcomes in an infertile population with adequate endometrial thickness. The beneficial effect of SC may be due not to an increase in EMT but instead to improve endometrial blood flow and receptivity, which might merit clinicians’ attention for improving general IVF practices.

Novel approaches to combat preeclampsia: from new drugs to innovative delivery

Preeclampsia is a complex disease affecting 2-8% of pregnancies worldwide. It poses significant risk of maternal and perinatal morbidity and mortality. Despite the rising research interest to discover new therapeutic approaches to prevent and treat preeclampsia, options remain limited. Identifying the important pathological stages in the progression of this disease allows us to evaluate effective candidate therapeutics. Three important stages in the pathophysiology are: 1) placental hypoxia and oxidative stress, 2) excess release of anti-angiogenic and pro-inflammatory factors, and 3) widespread systemic endothelial dysfunction and vasoconstriction. Repurposing drugs already safe for use in pregnancy is an attractive option for discovery of novel therapeutics. There are many drugs currently being assessed to treat preeclampsia, including proton pump inhibitors (PPIs), metformin, statins, sulfasalazine, sofalcone, resveratrol, melatonin, and sildenafil citrate. These drugs show positive effects in preclinical studies, targeting placental and endothelial dysfunction. However, using novel therapeutics can raise safety concerns for the developing fetus. Therefore, innovative targeted delivery systems are being developed to safely administer these therapeutics directly to the placenta and/or endothelium. These include nanoparticle delivery systems, developed and used by the oncology field, now being adapted for obstetrics. This technology is currently being assessed in animal models and shows promise for treating preeclampsia. Combining effective therapeutics with targeted drug delivery could be the future of preeclampsia treatment.

Neurotoxicity in pre-eclampsia involves oxidative injury, exacerbated cholinergic activity and impaired proteolytic and purinergic activities in cortex and cerebellum

Women with a history of pre-eclampsia (PE) tend to have a higher risk of developing cardiovascular and neurological diseases later in life. Imbalance in oxidative markers and purinergic enzymes have been implicated in the pathogenesis of neurological disease. This study investigated the effect of PE on oxidative imbalance, purinergic enzyme inhibitory activity, acetylcholinesterase and chymotrypsin activities in the brain of PE rat model at post-partum/post-natal day (PP/PND) 60. Pregnant rats divided into early-onset and late-onset groups were administered with Nω-nitro-l-arginine methyl through drinking water at gestational days 8-17. Rats were allowed free access to water throughout the pregnancy and allowed to deliver on their own. The mother and the pups were euthanized at PP and PND 60, respectively, the cortex and the cerebellum excised, homogenized and stored for analyses of the enzymes. Results showed an increase in nitric oxide and malondialdehyde with a concomitant decrease in reduced glutathione and superoxide dismutase, an indication of oxidative damage. Also, there was an increase in acetylcholinesterase activity with a decrease in chymotrypsin, adenylpyrophosphatase and ecto-nucleoside triphosphate diphosphohydrolase activities in both the cortex and the cerebellum of the mother and the pups at PND 60. These results indicate the involvement of oxidative stress, increased cholinergic activity and depleted proteolytic and purinergic activities in PE-induced neurotoxicity.

Hydroxychloroquine as a Preventive and Therapeutic Option in Preeclampsia - a Literature Review

Preeclampsia is one of the most feared complications of pregnancy and puerperium and represents a serious threat to mother and child. In addition, a history of preeclampsia increases the risk of future cardiovascular events. New diagnostic and therapeutic approaches are needed. New therapeutic options are currently being discussed, one of which is the administration of hydroxychloroquine. It is an antimalarial drug which is also used to treat rheumatological disease and its use in pregnancy is considered safe. A reduced incidence of preeclampsia in patients with selected rheumatological disorders after administration of hydroxychloroquine has already been shown; however, the case numbers are very low. Neither the full pathogenesis of preeclampsia nor the exact modes of action of hydroxychloroquine have been completely elucidated, but there are several common features which make hydroxychloroquine a promising option for the prevention and treatment of preeclampsia. Further research, especially prospective, randomized controlled trials, is needed to prove its efficacy. This review discusses the pathogenesis of preeclampsia and gives an overview of new options for its prevention and treatment, including the administration of hydroxychloroquine in pregnancy.

Sildenafil Citrate Does Not Reprogram Risk of Hypertension and Chronic Kidney Disease in Offspring of Preeclamptic Pregnancies in the Dahl SS/Jr Rat

Background

Preeclampsia is a disorder of pregnancy with accompanying high disease and economic burdens in the United States. Evidence supporting longstanding effects of preeclampsia on the offspring of affected pregnancies is high, but the effects of current antihypertensive therapies for preeclampsia on cardio-renal outcomes are largely unknown. The purpose of this study was to test the hypothesis that sildenafil citrate, a phosphodiesterase-5 inhibitor, reprograms the risk of hypertension and kidney disease in offspring of preeclamptic pregnancies by altering responses to secondary stressors.

Methods

Dahl SS/Jr rats on a 0.3% NaCl diet were mated. At gestational day 10, pregnant dams were randomized to vehicle diet or diet with sildenafil (50 mg/kg per day), which was continued until birth. Pups were weaned at 4 weeks of age and allowed to age on a 0.3% NaCl diet until 3 months of age. At this point, pups were randomized into three groups: baseline or no intervention, 2% NaCl diet challenge for 4 weeks, or a subpressor infusion of angiotensin II (200 ng/kg per minute) for 2 weeks.

Results

There were no differences among maternal treatment groups at baseline. Upon introduction of 2% NaCl diet, male offspring of sildenafil-treated dams exhibited an attenuated rise in BP; however, this protection was not observed during angiotensin II infusion.

Conclusions

Our findings indicate that intrapartum sildenafil does not reprogram the risk of hypertension and kidney disease in offspring of preeclamptic pregnancies.

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.

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.

Sodium Thiosulfate in the Pregnant Dahl Salt-Sensitive Rat, a Model of Preeclampsia

Aberrant production of hydrogen sulfide (H₂S) has been linked to preeclampsia. We hypothesized that sodium thiosulfate (STS), a H₂S donor, reduces hypertension and proteinuria, and diminishes fetal growth restriction in the Dahl salt-sensitive (S) rat, a spontaneous model of superimposed preeclampsia. In addition to a control group (n = 13), two groups received STS via drinking water at a dose of 2 g (n = 9) or 3 g per kg body weight per day (n = 8) from gestational day (GD) 10 to 20. Uterine artery resistance index was measured (GD18), urinary protein excretion rate was determined (GD19), and blood pressure and fetal outcomes were evaluated (GD20). At 2 g, STS had no effect on preeclamptic symptoms or fetal outcome. At 3 g, STS reduced maternal hypertension (121.8 ± 3.0 vs. 136.3 ± 2.9), but increased proteinuria (89 ± 15 vs. 56 ± 5 mg/24h), and relative kidney weight (0.86 ± 0.04 vs. 0.73 ± 0.02%). Fetal/placental weight ratio was reduced (3.83 ± 0.07 vs. 4.31 ± 0.08) without affecting litter size. No differences in uterine artery flow or renal histological damage were noted across treatment groups. While these data suggest a promising antihypertensive effect that could imply prolongation of preeclamptic pregnancies, the unfavorable effects on proteinuria, kidney weight, and fetal/placental weight ratio implies that clinical implementation of STS is contra-indicated until safety for mother and child can be verified.

Oligodendrocytes Death Induced Sensorimotor and Cognitive Deficit in N-nitro-L-arginine methyl Rat Model of Pre-eclampsia

Pre-eclampsia (PE) is a pregnancy complicated syndrome that affects multiple organs including the brain that continue post- delivery in both mother and the offspring. We evaluated the expression of oligodendrocytes in the brain of PE rat model through development as well as the cognitive changes and other behavioural modifications that may occur later in the life of offspring of PE-like rat model. Pregnant rats divided into early-onset and late-onset groups were administered with N-nitro- L-arginine methyl (L-NAME) through drinking water at gestational days (GD) 8-17. Rats were allowed free access to water throughout the pregnancy. At GD 19, post-natal day (PND) 1 and 60, rats were sacrificed and brain excised for further analysis. The offspring were subjected to behavioural studies for cognitive and sensorimotor impairments before sacrificed at PND 60. Results showed significant down-regulation in the expression of OLIG2 in PE at GD 19 brain which persists till PND 60. Likewise, there was a significant increase in the latency to locate the platform in Morris water maze, time to traverse the balance beam and reduced hanging time on the wire test between the control and the PE treated. PE could lead to impaired neuronal signalling through demyelination which may contributes significantly to long-term sensorimotor and cognitive deficit.

The effects of sildenafil in maternal and fetal outcomes in pregnancy: A systematic review and meta-analysis

BACKGROUND

The number of studies associating the use of sildenafil in gestation is increasing. This drug inhibits phosphodiesterase type 5 (PDE5), an enzyme responsible for degradation of nitric oxide, and its efficacy is greater in the placental territory, as the maternal side of the placenta have more PDE5 than other sites. For this reason, promising results have been observed related to the prevention of preeclampsia and intrauterine growth restriction and to improvement of maternal-fetal morbidity in cases of placental insufficiency.

OBJECTIVE

To evaluate the benefits of using sildenafil in pregnancy.

SEARCHED STRATEGY

MEDLINE, ClinicalTrials.gov, Embase, LILACS and Cochrane databases were searched through September 2018. There was no restriction in language or year of publication. This study was registered in PROSPERO (CRD42017060288).

SELECTION CRITERIA

Randomized clinical trials which used sildenafil for treatment or prevention of obstetric diseases compared with placebo were selected.

DATA COLLECTION AND ANALYSIS

The results were obtained using the inverse variance method for continuous variables and Man-Whitney for categorical variables.

MAIN RESULTS

Among a population of 598 pregnant women from the seven clinical trials included, 139 had pre-eclampsia, 275 had intrauterine growth restriction, and 184 had oligohydramnios. A significant increase of 222.58 grams [27.75 to 417.41] was observed in the fetal weight at birth of patients taking sildenafil. The other outcomes did not show any statistical significance. This may be due to the small number of patients used in each study and the great heterogeneity between the groups.

CONCLUSIONS

Sildenafil could be associated with increasing fetal weight at birth in placental insufficiency despite the limitations of this meta-analysis, even though more studies in this field are needed to introduce this drug into obstetric clinical practice.

Low Birth Weight, Blood Pressure and Renal Susceptibility

PURPOSE OF THE REVIEW

The purpose of this review is to highlight the clinical significance of increased renal risk that has its origins in fetal life. This review will also discuss the critical need to identify therapeutic interventions for use in a pregnancy complicated by placental dysfunction and intrauterine growth restriction that can mitigate the developmental origins of kidney disease without inflicting additional harm on the developing fetus.

RECENT FINDINGS

A reduction in nephron number is a contributory factor in the pathogenesis of hypertension and kidney disease in low birth weight individuals. Reduced nephron number may heighten susceptibility to a secondary renal insult, and recent studies suggest that perinatal history including birth weight should be considered in the assessment of renal risk in kidney donors. This review highlights current findings related to placental dysfunction, intrauterine growth restriction, increased risk for renal injury and disease, and potential therapeutic interventions.

Placental effects and transfer of sildenafil in healthy and preeclamptic conditions

Background

The phosphodiesterase-5 inhibitor (PDE5) sildenafil has emerged as a promising treatment for preeclampsia (PE). However, a sildenafil trial was recently halted due to lack of effect and increased neonatal morbidity.

Methods

Ex vivo dual-sided perfusion of an isolated cotyledon and wire-myography on chorionic plate arteries were performed to study the effects of sildenafil and the non-selective PDE inhibitor vinpocetine on the response to the NO donor sodium nitroprusside (SNP) under healthy and PE conditions. Ex vivo perfusion was also used to study placental transfer of sildenafil in 6 healthy and 2 PE placentas. Furthermore, placental mRNA and protein levels of eNOS, iNOS, PDE5 and PDE1 were quantified.

Findings

Sildenafil and vinpocetine significantly enhanced SNP responses in chorionic plate arteries of healthy, but not PE placentas. Only sildenafil acutely decreased baseline tension in arteries of both healthy and PE placentas. At steady state, the foetal-to-maternal transfer ratio of sildenafil was 0·37 ± 0·03 in healthy placentas versus 0·66 and 0·47 in the 2 PE placentas. mRNA and protein levels of PDE5, eNOS and iNOS were comparable in both groups, while PDE1 levels were lower in PE.

Interpretation

The absence of sildenafil-induced NO potentiation in arteries of PE placentas, combined with the non-PDE-mediated effects of sildenafil and the lack of PDE5 upregulation in PE, argue against sildenafil as the preferred drug of use in PE. Moreover, increased placental transfer of sildenafil in PE might underlie the neonatal morbidity in the STRIDER trial.

Fund

This study was funded by an mRACE Erasmus MC grant.

Spontaneous superimposed preeclampsia: chronology and expression unveiled by temporal transcriptomic analysis

Preeclampsia (PE), a multifactorial pregnancy-specific syndrome accounting for up to 8% of pregnancy complications, is a leading cause of maternal and fetal morbidity and mortality. PE is also associated with long-term risk of hypertension and stroke for both mother and fetus. Currently, the only "cure" is delivery of the baby and placenta, largely because the pathogenesis of PE is not yet fully understood. PE is associated with impaired vascular remodeling at the maternal-fetal interface and placental insufficiency; however, specific factors contributing to this impairment have not been identified. To identify molecular pathways involved in PE, we examined temporal transcriptomic changes occurring within the uterus, uterine implantation sites, and placentae from the Dahl salt-sensitive (Dahl S) rat model of superimposed PE compared with Sprague Dawley (SD) rats. We hypothesized that targeted gene analysis and whole transcriptome analysis would identify genetic factors that contribute to development of the preeclamptic phenotype in the Dahl S rat and unveil novel biomarkers, therapeutic targets, and mechanistic pathways in PE. Quantitative real-time PCR (qRT-PCR) and whole genome microarray analysis were performed on isolated total RNA from uterus (day 0), uterine implantation sites (days 7 and 10), and placenta (days 14 and 20). We found 624, 332, 185, and 366 genes to be differentially expressed between Dahl S (PE) and SD (normal pregnancy) on days 0, 7, 10, and 14, respectively. Our data revealed numerous pathways that may play a role in the pathophysiology of spontaneous superimposed PE and allow for further investigation of novel therapeutic targets and biomarker development.

Prenatal Sildenafil Therapy Improves Cardiovascular Function in Fetal Growth Restricted Offspring of Dahl Salt-Sensitive Rats

Fetal growth restriction (FGR) is associated with increased risk for cardiovascular and renal disorders in later life. Prenatal sildenafil improves birth weight in FGR animal models. Whether sildenafil treatment protects against long-term cardiovascular and renal disease in these offspring is unknown. The aim of this study is to test the hypothesis that prenatal sildenafil ameliorates cardiovascular and renal function in FGR offspring of Dahl salt-sensitive rats. Sildenafil citrate (60 mg/kg per day) or control gel diet (containing 0.3% salt) was administered from gestational day ten until birth. In male and female offspring, the mean arterial pressure was measured by telemetry in 1 subset from week 5 until week twenty. Echocardiographic parameters, glomerular filtration rate, and fractional electrolyte excretion were determined in another subset at week 9. Aortic and mesenteric artery rings were prepared to assess endothelial-dependent (acetylcholine) and -independent (sodium nitroprusside) vasorelaxation (week 10). The rise in mean arterial pressure per week was attenuated in treated versus untreated male offspring. Mesenteric arteries showed an increased endothelium-dependent relaxation and improved endothelium-independent relaxation in treated versus control male offspring. No differences in aortic relaxation, echocardiographic parameters or renal function were observed between groups. Prenatal sildenafil treatment subtly improves cardiovascular but not renal function in the offspring of this FGR rat model. Translationally, in utero treatment could be beneficial for cardiovascular programming in a sex-specific manner; however, caution is warranted since recent human trials have been halted because of potentially deleterious neonatal side effects when treating pregnancies complicated with severe FGR with sildenafil.

Aspirin causes endothelium-dependent vasodilation of resistance arteries from non-gravid and gravid rats

OBJECTIVE

The objective of this study was to understand the effect of acetylsalicylic acid (aspirin) on resistance arteries from mesentery and uterus. During pregnancy, the uterine vasculature undergoes consistent growth to provide sufficient uteroplacental blood flow, a process whose failure is associated with pregnancy complications characterized by high uterine vascular resistance.

METHODS

Uterine arcuate (UA) and mesenteric arteries (MA; diameter <300 µm) isolated from non-gravid, mid-gravid (day 14), and late-gravid rats (day 20) were exposed to aspirin (10^-12 to 10^-5 M). Further, in UA from late-gravid rats, aspirin was evaluated in presence of inhibitors of nitric oxide synthases, cyclooxygenase, cyclic nucleotides (cAMP, cGMP) and BK channels, and also on endothelium-denuded vessels.

RESULTS

Aspirin dilated both UA and MA in a dose dependent manner. Pregnancy increased aspirin vasodilation in MA and UA from mid-gravid rats, an effect that was reduced in vessels from late gravid animals at concentrations >10^-7 M. Further, uterine vasodilation was significantly reduced when the endothelium was removed (p < 0.001), and by inhibitors of nitric oxide synthase (p < 0.001), cyclooxygenase synthase (p < 0.05), cyclic nucleotides cGMP/cAMP and BK channels.

CONCLUSION

This is the first study to show a direct vasodilatory effect of aspirin on rat uterine artery that is mediated by a combination of cellular - primarily endothelial - mechanisms. Our results in UA suggest that the use of aspirin may be effective in enhancing uteroplacental blood flow, while its vasodilation effect on MA may lower peripheral resistance.

Sildenafil for the treatment of preeclampsia, an update: should we still be enthusiastic?

Preeclampsia is a hypertensive disorder of pregnancy and the clinical manifestation of severe endothelial dysfunction associated with maternal and foetal morbidity and mortality. The primum movens of the disease is the defect of invasion of the uterine arteries by foetal syncytiotrophoblasts, which causes a maladaptive placental response to chronic hypoxia and the secretion of the soluble form of type 1 vascular growth endothelial factor receptor, also called soluble fms-like tyrosine kinase 1 (sFlt-1), the major player in the pathophysiology of the disease. Among its different effects, sFlt-1 induces abnormal sensitivity of the maternal vessels to the vasoconstrictor angiotensin II. This leads to the hypertensive phenotype, recently shown to be abrogated by the administration of sildenafil citrate, which can potentiate the vasodilatory mediator nitrite oxide. This review focuses on the mechanisms of maternal endothelial dysfunction in preeclampsia and discusses the therapeutic window of sildenafil use in the context of preeclampsia, based on the results from preclinical studies and clinical trials. Safety issues recently reported in neonates have considerably narrowed this window.

Phosphodiesterase Inhibition in the Treatment of Preeclampsia: What Is New?

PURPOSE OF REVIEW

The present study intends to review the possibility of using phosphodiesterase inhibitors as a treatment option for preeclampsia, addressing potential risks and benefits.

RECENT FINDINGS

Preeclampsia is the most common hypertensive disorder of pregnancy, often responsible for severe maternal and fetal complications, which can lead to early pregnancy termination and death. Despite the numerous studies, its pathophysiology is still unclear, although it seems to involve a multiplicity of complex factors related to angiogenesis, ineffective vasodilation, oxidative stress, inflammatory cytokines, and endothelial dysfunction. It has been hypothetically suggested that the use of phosphodiesterase inhibitors is capable of improving placental and fetal perfusion, contributing to gestational scenario, by decreasing the symptomatology and severity of this syndrome. In this literature review, it has been found that most of the studies were conducted in animal models, and there is still lack of evidence supporting its use in clinical practice. Research in human indicates conflicting findings; randomized controlled trials were scarce and did not demonstrate any benefit in morbidity or mortality. Data regarding to pathophysiological and interventional research are described and commented in this review. The use of phosphodiesterase inhibitors in the treatment of preeclampsia is controversial and should not be encouraged taking into account recent data.

The Endothelin System: A Critical Player in the Pathophysiology of Preeclampsia

PURPOSE OF REVIEW

Preeclampsia (PE) is a disorder of pregnancy typically characterized by new-onset hypertension and proteinuria after gestational week 20. Although preeclampsia is one of the leading causes of maternal and perinatal morbidity and death worldwide, the mechanisms of the pathogenesis of the disorder remain unclear and treatment options are limited. Placental ischemic events and the release of placental factors appear to play a critical role in the pathophysiology. These factors contribute to a generalized systemic vascular endothelial dysfunction and result in increased systemic vascular resistance and hypertension.

RECENT FINDINGS

There is increasing evidence to suggest that endothelin-1 (ET-1) in the maternal vascular endothelium is a critical final common pathway, whereby placental ischemic factors cause cardiovascular and renal dysfunction in the mother. Multiple studies report increased levels of ET-1 in PE. A number of experimental models of PE are also associated with elevated tissue levels of prepro-ET-1 mRNA. Moreover, experimental models of PE (placental ischemia, sFlt-1 excess, TNF-α excess, and AT1-AA infusion) have proven to be responsive to ET type A receptor antagonism. Recent studies also suggest that abnormalities in ET type B receptor signaling may also play a role in PE. Although numerous studies highlight the importance of the ET system in the pathogenesis of PE, further work is needed to determine whether ET receptor antagonists could provide an effective therapy for the management of this disease.

Systemic Evaluation of Vascular Dysfunction by High-Resolution Sonography in an Nω -Nitro-l-Arginine Methyl Ester Hydrochloride-Induced Mouse Model of Preeclampsia-Like Symptoms

OBJECTIVES

The purpose of this study was to evaluate vascular function, including arterial resistance and endothelial function, by high-resolution sonography in an N_ω -nitro-l-arginine methyl ester hydrochloride (l-NAME)-induced mouse model of preeclampsia-like symptoms.

METHODS

Pregnant mice were subcutaneously injected with a saline solution (control; n = 10) or l-NAME (n = 10) between the 7th and 18th days of gestation. The resistive index and pulsatility index (RI and PI, indicators of arterial resistance) of the uteroplacental, umbilical, femoral, and common carotid arteries and the flow-mediated dilatation (index of endothelial function) of the femoral artery were measured by high-frequency sonography in both groups.

RESULTS

We noted significant increases in the RI and PI of the uteroplacental and umbilical arteries and a decrease in the flow-mediated dilatation of the femoral artery in the l-NAME group compared with the control group. We also found that the RI and PI of the uteroplacental and umbilical arteries were negatively correlated with fetal weight and crown-rump length. The results of the multivariate analysis using a logistic regression model indicated that the flow-mediated dilatation at 120 seconds was an independent diagnostic criterion for the l-NAME-induced preeclampsia-like model. A receiver operating characteristic analysis showed that flow-mediated dilatation at 120 seconds had the greatest area under the curve of 0.934, with an optimal cutoff point of 11.1%, yielding sensitivity of 100% and specificity of 84.6%.

CONCLUSIONS

The PI and RI of the fetomaternal vasculature can identify fetuses in "high-risk" pregnancies, and flow-mediated dilatation is a reliable indicator for predicting preeclampsia. Assessment of vascular function by high-resolution sonography provides a useful platform for preeclampsia-related basic research with high reproducibility.

Maternal hypertension and feto-placental growth restriction is reversed by sildenafil: Evidence of independent effects of circulating nitric oxide levels

Sildenafil has shown nitric oxide (NO)-independent pleiotropic effects, however the mechanisms involved are unclear. We investigated the protective effects of sildenafil against hypertension in pregnancy and feto-placental growth restriction induced by NO inhibition, and if sodium nitrite-derived NO formation influences sildenafil effects. We evaluated the plasmatic levels of NO metabolites, cyclic guanosine monophosphate (cGMP), oxidative stress and myeloperoxidase, which are involved in endothelial dysfunction during hypertension in pregnancy. Also, we performed in vitro experiments to examine cell viability and NO synthesis in human umbilical vein endothelial cells (HUVECs) cultures incubated with plasma from healthy or hypertensive pregnant rats treated (or not) with both drugs, either alone or in association. Sildenafil blunted hypertension in pregnancy and protected against feto-placental growth restriction induced by NO inhibition and these effects of sildenafil alone were similar to those presented by its association with sodium nitrite. Protective effects of sildenafil were observed even with low plasmatic NO levels and were not followed by increases in cGMP levels. Also, sildenafil, but not sodium nitrite, blunted the increases in myeloperoxidase activity. Both drugs (isolated or in association) presented antioxidant effects. Plasma from hypertensive pregnant rats treated with sildenafil, but not sodium nitrite alone, increased the viability of HUVECs. NO synthesis in HUVECs cultures was increased with plasma from rats treated with both drugs. We conclude that sildenafil effects are not dependent of circulating NO levels in hypertension and feto-placental growth restriction. These findings may reflect a protection against myeloperoxidase and pro-oxidant activation in hypertension in pregnancy.

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.

Molecular mechanisms for vascular complications of targeted cancer therapies

Molecularly targeted anti-cancer therapies have revolutionized cancer treatment by improving both quality of life and survival in cancer patients. However, many of these drugs are associated with cardiovascular toxicities that are sometimes dose-limiting. Moreover, the long-term cardiovascular consequences of these drugs, some of which are used chronically, are not yet known. Although the scope and mechanisms of the cardiac toxicities are better defined, the mechanisms for vascular toxicities are only beginning to be elucidated. This review summarizes what is known about the vascular adverse events associated with three classes of novel anti-cancer therapies: vascular endothelial growth factor (VEGF) inhibitors, breakpoint cluster-Abelson (BCR-ABL) kinase inhibitors used to treat chronic myelogenous leukaemia (CML) and immunomodulatory agents (IMiDs) used in myeloma therapeutics. Three of the best described vascular toxicities are reviewed including hypertension, increased risk of acute cardiovascular ischaemic events and arteriovenous thrombosis. The available data regarding the mechanism by which each therapy causes vascular complication are summarized. When data are limited, potential mechanisms are inferred from the known effects of inhibiting each target on vascular cell function and disease. Enhanced understanding of the molecular mechanisms of vascular side effects of targeted cancer therapy is necessary to effectively manage cancer patients and to design safer targeted cancer therapies for the future.

Mechanisms and Treatment of Halogen Inhalation-Induced Pulmonary and Systemic Injuries in Pregnant Mice

Inhalation of oxidant gases has been implicated in adverse outcomes in pregnancy, but animal models to address mechanisms and studies to identify potential pregnancy-specific therapies are lacking. Herein, we show that inhalation of bromine at 600 parts per million for 30 minutes by pregnant mice on the 15th day of embryonic development results in significantly lower survival after 96 hours than an identical level of exposure in nonpregnant mice. On the 19th embryonic day, bromine-exposed pregnant mice have increased systemic blood pressure, abnormal placental development, severe fetal growth restriction, systemic inflammation, increased levels of circulating antiangiogenic short fms-like tyrosine kinase-1, and evidence of pulmonary and cardiac injury. Treatment with tadalafil, an inhibitor of type 5 phosphodiesterase, by oral gavage 1 hour post-exposure and then once daily thereafter, attenuated systemic blood pressures, decreased inflammation, ameliorated pulmonary and cardiac injury, and improved maternal survival (from 36% to 80%) and fetal growth. These pathological changes resemble those seen in preeclampsia. Nonpregnant mice did not exhibit any of these pathological changes and were not affected by tadalafil. These findings suggest that pregnant women exposed to bromine may require particular attention and monitoring for signs of preeclampsia-like symptoms.

The effects of pravastatin on the normal human placenta: Lessons from ex-vivo models

Introduction

Research in animal models and preliminary clinical studies in humans support the use of pravastatin for the prevention of preeclampsia. However, its use during pregnancy is still controversial due to limited data about its effect on the human placenta and fetus.

Methods

In the present study, human placental cotyledons were perfused in the absence or presence of pravastatin in the maternal reservoir (PraM). In addition, placental explants were treated with pravastatin for 5, 24 and 72 h under normoxia and hypoxia. We monitored the secretion of placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), soluble endoglin (sEng), endothelial nitric oxide synthase (eNOS) expression and activation and the fetal vasoconstriction response to angiotensin-II.

Results

The concentrations of PlGF, sFlt-1 and sEng were not significantly altered by pravastatin in PraM cotyledons and in placental explants compared to control. Under hypoxic conditions, pravastatin decreased sFlt-1 concentrations. eNOS expression was significantly increased in PraM cotyledons but not in pravastatin-treated placental explants cultured under normoxia or hypoxia. eNOS phosphorylation was not significantly affected by pravastatin. The feto-placental vascular tone and the fetal vasoconstriction response to angiotensin-II, did not change following exposure of the maternal circulation to pravastatin.

Conclusion

We found that pravastatin does not alter the essential physiological functions of the placenta investigated in the study. The relevance of the study lays in the fact that it expands the current knowledge obtained thus far regarding the effect of the drug on the normal human placenta. This data is reassuring and important for clinicians that consider the treatment of high-risk patients with pravastatin, a treatment that exposes some normal pregnancies to the drug.

The effects of sildenafil citrate on uterine angiogenic status and serum inflammatory markers in an L-NAME rat model of pre-eclampsia

Pre-eclampsia (PE), a hypertensive disorder of pregnancy, is detrimental to both mother and foetus. There is currently no effective treatment, but we have shown that Sildenafil Citrate (SC) improve various foetal outcomes in N^ω-nitro-L arginine methyl ester (L-NAME) rat model of PE. Therefore, we aimed to investigate the effects of SC on a uterine angiogenic status and serum inflammatory markers in an L-NAME rat model of PE. One hundred and twenty adult nulliparous pregnant female Sprague-Dawley rats were used for the study. These were divided into five equal groups; the pregnant control, early and late onset PE and respective SC treated animals. Hypertension was manifested by considerably increased systolic blood pressure and placental lipid peroxidative marker (thiobarbituric acid reactive substances) and also we assessed the activities of plasma nitric oxide level, serum inflammatory marker (TGF-β and IFN-γ) and uterine angiogenic status (VEGF and sFlt-1) at two stages of PE. The administration of SC decreased systolic blood pressure, placental lipid peroxidation product and altered uterine angiogenic status; increased plasma nitric oxide levels in an early and late onset L-NAME model of PE. In addition, histological findings of SC treated preeclamptic rat placenta support the biochemical findings of this study. Our findings revealed that SC enhanced plasma NO levels and uterine angiogenic status in an L-NAME model of PE at two gestational stages.