Suppression of aldosterone and progesterone in preeclampsia

The mediating role of steroid hormones in the relationship between bisphenol A and its alternatives bisphenol S and F exposure and preeclampsia

Steroid hormone imbalance is believed to increase the odds of developing PE. Bisphenol A (BPA) and its substitutes (e.g., bisphenol S (BPS) and bisphenol F (BPF)) have estrogen-like effects, and its exposure may be related to the development of preeclampsia (PE). To explore the effects of bisphenol exposure on maternal serum steroid hormones and the potential mediating role of steroid hormones in the association between bisphenol exposure and developing PE, concentrations of bisphenols and steroid hormones in serum samples of 383 pregnant women were examined before delivery (including 160 PE cases and 223 control cases). Multivariable logistic and linear models were used to explore the associations of maternal serum bisphenols concentrations with both maternal steroid hormones and PE risk. Mediation modeling was employed to evaluate the mediating role of steroid hormones in the association between bisphenols and PE. Results showed that maternal serum BPS concentrations were positively associated with testosterone (T) concentrations. The mediation analyses suggested that approximately 10.17 % of the associations between BPS concentrations and the development of PE might be mediated by maternal T. In conclusion, maternal exposure to BPS during pregnancy is linked to higher maternal T concentrations, which might increase the odds of developing PE. T might mediate the association between BPS exposure and the development of PE.

The dilemma of sodium intake in preeclampsia: beneficial or detrimental?

Preeclampsia (PE) is a disorder involving de novo development of hypertension plus end organ damage after 20 weeks of gestation. PE is considered to be a heterogeneous disease. There are 2 main types of PE: early-onset (<34 weeks of gestation), which is considered to be a placental disorder and is associated with vasoconstriction, low cardiac output, and placental hypoperfusion and organ damage due to decreased microcirculation to maternal organs; and late-onset PE, which is primarily a disorder of pregnant women with obesity, diabetes, and/or cardiovascular abnormalities. In late-onset PE, there is avid sodium reabsorption by the maternal kidneys, causing hypervolemia and increased cardiac output, along with vasodilatation causing venous congestion of organs. Although PE has been a well-known disease for a long time, it is interesting to note that there is no specific sodium (salt) intake recommendation for these patients. This may be due to the fact that studies since as far back as the 1900s have shown conflicting results, and the reasons for the inconsistent findings have not been fully explained; furthermore, the type of PE in these studies was not specifically defined. Some studies suggest that sodium restriction may be detrimental in early-onset PE, but may be feasible in late-onset PE. To explore this paradox, the current review explains the hemodynamic factors involved in these 2 types of PE, summarizes the findings of the current studies, and highlights the knowledge gaps and the research needed to determine whether increase or restriction of salt or sodium intake is beneficial in different types of PE.

Galectin-7 dysregulates renin-angiotensin-aldosterone and NADPH oxide synthase pathways in preeclampsia

OBJECTIVES

Preeclampsia is a life-threatening disorder of pregnancy unique to humans. Poor placentation in the first trimester of pregnancy is widely accepted to be an underlying cause of preeclampsia. Galectin-7 is abnormally elevated in chorionic villous samples and serum from women that subsequently develop pre-term preeclampsia. Administration of exogenous galectin-7 to pregnant mice causes preeclampsia-like features (hypertension, proteinuria), associated with dysregulation of the renin-angiotensin system (RAS). In this study investigated the mechanism by which galectin-7 induces alterations to tissue RAS homeostasis and ROS production. We hypothesized that galectin-7 induces alterations in the production of either placental RAS or NADPH oxidases (or both) to drive the dysregulated RAS and ROS production seen in preeclampsia.

STUDY DESIGN

Mated female mice (n = 5-6/group) received single (embryonic day [E]12/13) or multiple (E8-12) subcutaneous injections of 400 μg/kg/day galectin-7 or vehicle control and killed on E13 or E18. Human first trimester placental villous and decidual tissue (n = 11) was cultured under 8 % oxygen with 1 µg/mL galectin-7 or vehicle control for 16 h.

RESULTS

Galectin-7 administration to pregnant mice impaired placental labyrinth formation, suppressed circulating aldosterone and altered placental RAS (Agt, Renin) and NADPH oxidase (Cyba, Cybb and Icam1) mRNA expression. In vitro, galectin-7 regulated human placental villous RAS (AGT) and NADPH oxidase (CYBA, ICAM1 and VCAM1) mRNA expression.

CONCLUSIONS

Overall, galectin-7 likely drives hypertension in preeclampsia via its direct regulation of multiple pathways associated with preeclampsia in the placenta. Galectin-7 may therefore be a therapeutic target to improve placental function and prevent preeclampsia.

Is urinary excretion of plasminogen associated with development of pre-eclampsia? An observational, explorative case-control study

OBJECTIVES

Pre-eclampsia (PE) is characterised by renal glomerular endotheliosis and injury to the glomerular filtration barrier with proteinuria. Patients with PE display aberrant filtration of the plasma proenzyme plasminogen which is activated, in the tubular fluid, to plasmin. Plasmin may activate the epithelial sodium channel and cause impaired sodium excretion and contribute to hypertension. An explorative study was conducted to test the association between urinary total plasminogen/plasmin and the development of PE. A positive association was hypothesised.

DESIGN

An observational, explorative, nested case-control study of healthy pregnant women.

SETTINGS

A Danish County hospital. Samples were collected between 2001 and 2004.

PARTICIPANTS

1631 healthy pregnant women participated. Urine samples were collected longitudinally six times during pregnancy. 30 developed PE (cases) and were compared with 146 randomly selected healthy pregnant women (controls).

PRIMARY OUTCOME

The association between total plasminogen/plasmin excreted in the urine and PE development is expressed by ORs. Total urinary excretion of plasminogen/plasmin was defined by the urine plasminogen-plasmin/creatinine ratio.

SECONDARY OUTCOME

The association between urine (u)-albumin/creatinine ratio, u-aldosterone/creatinine ratio and PE development is expressed by ORs. The correlation between urinary (u-) plasmin and u-aldosterone concentration is expressed as a correlation coefficient.

RESULTS

The development of PE in late pregnancy was associated with increased levels of the urine plasminogen-plasmin/creatinine ratio (OR=2.35; 95% CI: 1.12 to 4.93; p<0.05).U-aldosterone/creatinine ratio did not predict PE at any time. U-albumin/creatinine ratio was positively associated with the development of PE from gestational week 33 (OR=14.04; 95% CI: 2.56 to 76.97; p<0.01) and in week 33-35 (OR=14.15; 95% CI: 3.44 to 58.09; p<0.001) and after gestational week 36, respectively.

CONCLUSION

Aberrant filtration of plasminogen may contribute to the pathophysiological features of impaired sodium excretion and hypertension associated with PE late in pregnancy. However, increased urinary albumin levels reveal stronger associations with PE development compared with urinary plasminogen levels.

Aldosterone, Salt, and Potassium Intakes as Predictors of Pregnancy Outcome, Including Preeclampsia

The mineralocorticoid aldosterone increases in plasma in healthy pregnancy along with renin and angiotensin II and plays a key role in the physiological plasma volume expansion. In mice, aldosterone contributes to an optimal fetal development by enhancing PlGF (placental growth factor) expression and trophoblast cell proliferation. In preeclampsia, there is coincident suppression of aldosterone and impaired placental development. We hypothesized that aldosterone independently contributes to placental and birth weight in humans, and high dietary sodium and low potassium intakes affect this relationship adversely. We analyzed 24-hour urine collections and plasma samples from gestational week 29 in a subsample of 569 pregnant women from the Odense Child Cohort-a Danish population-based longitudinal cohort study. Plasma and urinary aldosterone were measured by ELISA, sodium and potassium excretions by flame photometer. Predictive values of aldosterone levels and sodium and potassium intakes were assessed by multiple and Cox regression analyses. Primary outcomes were placental weight and birth weight. Secondary outcome was preeclampsia. Urinary aldosterone excretion at gestational week 29 independently contributed to placental and birth weights (adjusted β-coefficients [95% CI], 24.50 [9.66-39.35] and 9.59 [4.57-14.61], respectively). Aldosterone levels were not associated to preeclampsia incidence. Salt intake >6 g/d was associated with development of preeclampsia (hazard ratio [95% CI], 5.68 [1.51-21.36]). At gestational week 29, urinary aldosterone excretion is an independent predictor of placental and birth weights. High salt intake is a risk factor for preeclampsia. In perspective, suppression of aldosterone in pregnancy has adverse trophic effects.

Responses of the renin-angiotensin-aldosterone system in pregnant chronic kidney disease patients with and without superimposed pre-eclampsia

Background

Women with chronic kidney disease (CKD) are at increased risk of superimposed pre-eclampsia (SPE). Accurate identification of SPE is challenging. We hypothesized that specific components of the renin-angiotensin-aldosterone system (RAAS) would discriminate between CKD and SPE. The aim of the study was to establish differences in circulating and intrarenal RAAS in women with CKD with and without SPE and compare these to normotensive controls (NCs) and women with pre-eclampsia (PE).

Methods

White European NC women (n = 20), women with PE (n = 9), normotensive CKD without SPE (n = 8) and with SPE (n = 11) were recruited in the third trimester. Plasma renin, plasma and urine total angiotensinogen (AGT) concentrations were quantified by enzyme-linked immunosorbent assay, urinary tetrahydroaldosterone (TH-aldo) concentration by gas chromatography-mass spectrometry and placental growth factor (PlGF) by immunoassay.

Results

Urinary TH-aldo:creatinine ratios were lower in women with PE or SPE compared with NC or women with CKD (P < 0.05 for all). The same group differences were observed for plasma active renin and PlGF concentrations (P < 0.05 for all). Urine total AGT was higher in women with PE compared with NC (P < 0.05) and urine TH-aldo:urine AGT was lower (P < 0.05). However, women with SPE had lower urinary AGT concentrations compared with women with PE (P < 0.05). No differences in plasma total AGT were observed between groups.

Conclusions

Women with SPE have a lower urinary TH-aldo:creatinine ratio, lower plasma active renin and lower PlGF concentrations than women with CKD, comparable to women with PE without pre-existing disease, suggestive of similar pathophysiology. These data suggest disruption of the RAAS pathway in SPE similar to PE. Exploration of the predictive value of RAAS components for adverse pregnancy events in women with CKD is required.

Causes and Consequences of the Dysregulated Maternal Renin-Angiotensin System in Preeclampsia

A healthy pregnancy outcome depends on the activation of the renin-angiotensin-aldosterone system (RAAS) as a regulated, integrated response to the growing demands of the conceptus. Both the circulating RAAS and the intrarenal renin-angiotensin system (iRAS) play major roles in cardiovascular function and fluid and electrolyte homeostasis. The circulating RAAS becomes dysfunctional in preeclampsia and we propose that dysregulation of the iRAS plays a role in development of the clinical syndrome known as preeclampsia. Experimental studies in animals have shown that placental renin, when released into the maternal circulation, can cause hypertension. We postulate that abnormal placental development is associated with over-secretion of renin and other RAS proteins/angiotensin (Ang) peptides by the placenta/decidua into the maternal circulation. We hypothesise that this is because of increased shedding of exosomes and other placental particles into the maternal circulation that not only contain RAS proteins and peptides but also microRNAs (miRNAs) that target RAS mRNAs, and Ang II type 1 receptor autoantibodies (AT₁R-AAs), that are agonists for, and have the same actions as, Ang II. As a result, there is both suppression of the circulating RAAS that is responsible for maintaining maternal homeostasis and activation of the iRAS. Together with altered vascular reactivity to Ang peptides, the iRAS causes hypertension, renal damage and secondary changes in the neurohumoral control of the maternal circulation and fluid and electrolyte balance, which contribute to the pathophysiology of preeclampsia.

Multimodal Regulation of NET Formation in Pregnancy: Progesterone Antagonizes the Pro-NETotic Effect of Estrogen and G-CSF

Human pregnancy is associated with a mild pro-inflammatory state, characterized by circulatory neutrophil activation. In order to explore the mechanism underlying this alteration, we examined NETosis during normal gestation. Our data indicate that neutrophils exhibit a pro-NETotic state, modulated in a multimodal manner during pregnancy. In general, circulatory granulocyte colony-stimulating factor, the levels of which increase during gestation, promotes neutrophil extracellular trap (NET) formation. Early in pregnancy, NETosis is enhanced by chorionic gonadotropin, whereas toward term is stimulated by estrogen. A complex interaction between estrogen and progesterone arises, wherein progesterone restrains the NETotic process. In this state, extensive histone citrullination is evident, yet full NETosis is inhibited. This coincides with the inability of neutrophil elastase to translocate from the cytoplasm to the nucleus and is regulated by progesterone. Our findings provide new insight concerning gestational and hormone-driven pathologies, since neutrophil recruitment, activation, and NET release could be associated with excessive endothelial and placental injury.

Sex Steroids Modulate Uterine-Placental Vasculature: Implications for Obstetrics and Neonatal Outcomes

Adequate blood supply to the uterine-placental region is crucial to ensure the transport of oxygen and nutrients to the growing fetus. Multiple factors intervene to achieve appropriate uterine blood flow and the structuring of the placental vasculature during the early stages of pregnancy. Among these factors, oxygen concentrations, growth factors, cytokines, and steroid hormones are the most important. Sex steroids are present in extremely high concentrations in the maternal circulation and are important paracrine and autocrine regulators of a wide range of maternal and placental functions. In this regard, progesterone and estrogens act as modulators of uterine vessels and decrease the resistance of the spiral uterine arteries. On the other hand, androgens have the opposite effect, increasing the vascular resistance of the uterus. Moreover, progesterone and estrogens modulate the synthesis and release of angiogenic factors by placental cells, which regulates trophoblastic invasion and uterine artery remodeling. In this scenario, it is not surprising that women with pregnancy-related pathologies, such as early miscarriages, preterm delivery, preeclampsia, and fetal growth restriction, exhibit altered sex steroid concentrations.

11β-Hydroxysteroid Dehydrogenase 2 in Preeclampsia

Preeclampsia is a serious medical problem affecting the mother and her child and influences their health not only during the pregnancy, but also many years after. Although preeclampsia is a subject of many research projects, the etiology of the condition remains unclear. One of the hypotheses related to the etiology of preeclampsia is the deficiency in placental 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2), the enzyme which in normal pregnancy protects the fetus from the excess of maternal cortisol. The reduced activity of the enzyme was observed in placentas from pregnancies complicated with preeclampsia. That suggests the overexposure of the developing child to maternal cortisol, which in high levels exerts proapoptotic effects and reduces fetal growth. The fetal growth restriction due to the diminished placental 11β-HSD2 function may be supported by the fact that preeclampsia is often accompanied with fetal hypotrophy. The causes of the reduced function of 11β-HSD2 in placental tissue are still discussed. This paper summarizes the phenomena that may affect the activity of the enzyme at various steps on the way from the gene to the protein.

Pre-eclampsia has an adverse impact on maternal and fetal health

Pre-eclampsia (preE) is a multifaceted complication found uniquely in the pregnant patient and one that has puzzled scientists for years. PreE is not a single disorder, but a complex syndrome that is produced by various pathophysiological triggers and mechanisms affecting about 5% of obstetrical patients. PreE is a major cause of premature delivery and maternal and fetal morbidity and mortality. PreE is characterized by de novo development of hypertension and proteinuria after 20 weeks of gestation and affects nearly every organ system, with the most severe consequences being eclampsia, pulmonary edema, intrauterine growth restriction, and thrombocytopenia. PreE alters the intrauterine environment by modulating the pattern of hormonal signals and activating the detrimental cellular signaling that has been transported to the fetus. The fetus has to adapt to this intrauterine environment with detrimental signals. The adaptive changes increase the risk of disease later in life. This review defines the predisposition and causes of preE and the cellular signaling detrimental to maternal health during preE. Moreover, the risk factors for diseases that are transmitted to the offspring have been addressed in this review. The detrimental signaling molecules that have been overexpressed in preE patients raises the possibility that those signals could be therapeutically blocked one day.

ENaC mediates human extravillous trophblast cell line (HTR8/SVneo) invasion by regulating levels of matrix metalloproteinase 2 (MMP2)

INTRODUCTION

Placenta dysfunction is thought to be the major etiological factor related to preeclampsia. The epithelial sodium channel (ENaC) has been localized in the apical plasma membrane of epithelia, mediating the active reabsorption of sodium in kidney, and be involved in the regulation of blood pressure. In previous studies, we found that the reduced expression of ENaC on placenta in preeclampsia patients. The aim of this study was to determine the role of MMP2 in the ENaC-induced trophoblast cell invasion ability, which is closely related to the occurrence of preeclampsia.

METHODS

Here we checked whether pregnancy related hormones human chorionic gonadotropin (HCG), prolactin and aldosterone could affect ENaC expression in the first trimester extravillous trophoblast cell line (HTR8/SVneo) by RT-PCR and Western blot. Cell invasion was studied by matrigel invasion assay. Tube formation assay was used to investigate the interaction between trophoblast cells and endothelial cells. The effects of ENaC on MMP2 were further determined by RT-PCR, western blot and gelatin zymography.

RESULTS

We demonstrated that HCG, prolactin and aldosterone could up-regulate the expression of αENaC in protein levels. Trophoblast cell invasion ability is stimulated when αENaC was up-regulated by aldosterone, and inhibited when ENaC was down-regulated by amiloride and αENaC specific RNAi (SiENA/ENaC). The interaction between HTR8/SVneo cells and HUVEC cells was enhanced when treated with aldosterone and weakened when treated with amiloride and SiRNA/ENaC. Amiloride and SiRNA/ENaC could inhibit MMP2 expression and activity.

DISSCUTION

Aldosterone induced ENaC activity is important for trophoblast cells invasion. The results also indicate that ENaC could mediate trophoblast cells invasion ability through regulating expression and activity of matrix metalloproteinase-2 (MMP2).