The renal response to preeclampsia

Environmental exposure to metal(loid)s and hypertensive disorders of pregnancy: A systematic review

BACKGROUND

Environmental exposure to metal(loid)s has been associated with adverse effects on human health, but the systemic repercussion of these elements on the development of hypertensive disorders of pregnancy (HDP) is still poorly understood.

OBJECTIVE

To summarize evidence published about the influence of environmental exposure to aluminum, arsenic, barium, cadmium, lead, strontium and mercury on the development of HDP.

METHODS

We conducted a systematic literature review according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The search strategy was validated by the Peer Review of Electronic Search Strategies. We searched for articles published up to February 2023 in seven databases without language restriction. Two researchers conducted the steps for selection, data extraction and evaluation of the methodological quality of the instruments for epidemiological studies of the Joanna Briggs Institute. Any disagreements were resolved by a third researcher.

RESULTS

We obtained 5076 records, of which 37 articles met the inclusion criteria moderate to high methodological quality. Single exposure to metal(loid)s was predominant, and the leading biological matrix analyzed to detect the concentrations from exposure was maternal blood. Lead was the metal investigated the most, and had the largest number of studies showing positive association with HDP. In relation to the other metal(loid)s, higher levels were found in women with HDP in comparison with healthy women, but the finding of a cause-effect relationship was inconsistent.

CONCLUSIONS

Although we found evidence of harmful effects of the metal(loid)s studied on human health, the results were inconclusive with regard to HDP. Longitudinal studies that consider prospective investigation, adjustment of confounding factors and the interference of other contaminants in the exacerbation of oxidative stress in women from the preconception phase to the puerperal period should be encouraged.

The Role of Endothelial Dysfunction in the Pathogenesis of Pregnancy-Related Pathological Conditions: A Review

In the recent decades, endothelial dysfunction (ED) has been recognized as a significant contributing factor in the pathogenesis of many pathological conditions. In interaction with atherosclerosis, hypercholesterolemia, and hypertension, ED plays a crucial role in the pathogenesis of coronary artery disease, chronic renal disease, and microvascular complications in diabetes mellitus. Although ED plays a significant role in the pathogenesis of several pregnancy-related disorders such as preeclampsia, HELLP syndrome, fetal growth restriction, and gestational diabetes mellitus, the exact pathogenetic mechanisms are still a matter of debate. The increased prevalence of these entities in patients with preexisting vascular diseases highlights the essential pathological role of the preexisting ED in these patients. The abnormal uteroplacental circulation and the release of soluble factors from the ischemic placenta into the maternal bloodstream are the main causes of the maternal ED underlying the characteristic preeclamptic phenotype. Besides the increased risk for maternal and fetal poor outcomes, the preexisting ED also increases the risk of development of future cardiovascular diseases in these patients. This study aimed to look deeper into the role of ED in the pathogenesis of several pregnancy-related hypertensive and liver diseases. Hopefully, it could contribute to improvement of the awareness, knowledge, and management of these conditions and also to the reduction of the adverse outcomes and additional long-term cardiovascular complications.

Kidney injury molecule-1 and podocalyxin dysregulation in an arginine vasopressin induced rodent model of preeclampsia

OBJECTIVE

To assess renal injury in an arginine vasopressin (AVP) rodent model of preeclampsia.

STUDY DESIGN

Urinary expression of kidney injury molecule-1 (KIM-1), urinary protein and creatinine was determined in rodents (n = 24; pregnant AVP, pregnant saline, non-pregnant AVP and non-pregnant saline), which received a continuous dose of either AVP or saline via subcutaneous mini osmotic pumps for 18 days, using a Multiplex kidney toxicity immunoassay. Renal morphology was assessed using haematoxylin and eosin staining and transmission electron microscopy. The immunolocalization of KIM-1 and podocalyxin was qualitatively evaluated using immunohistochemistry.

RESULTS

Urinary KIM-1 and urinary protein levels were significantly increased in treated vs. untreated rats on gestational days 8 (p < 0.05), 14 (p < 0.001) and 18 (p < 0.001). The pregnant rats displayed a lower trend of creatinine compared to the non-pregnant groups, albeit non-significantly. KIM-1 was immunolocalized in the proximal convoluted tubules in AVP treated vs. untreated groups. In contrast, podocalyxin was weakly immunostained within glomeruli of pregnant AVP treated vs. pregnant untreated rats. Histological evaluation revealed reduced Bowman's space, with some tubular and blood vessel necrosis in the pregnant treated group. Ultrastructural observations included effacement and fusion of podocyte foot processes, glomerular basement membrane abnormalities, podocyte nuclear crenations, mitochondrial oedema and cristae degeneration with cytoplasmic lysis within treated tissue.

CONCLUSION

Our findings demonstrate region-specific kidney injury particularly glomerular impairment and endothelial injury in AVP-treated rats. The findings highlight the utility of this model in studying the mechanisms driving renal damage in a rodent model of preeclampsia.

The Role of Macula Densa Nitric Oxide Synthase 1 Beta Splice Variant in Modulating Tubuloglomerular Feedback

Abnormalities in renal electrolyte and water excretion may result in inappropriate salt and water retention, which facilitates the development and maintenance of hypertension, as well as acid-base and electrolyte disorders. A key mechanism by which the kidney regulates renal hemodynamics and electrolyte excretion is via tubuloglomerular feedback (TGF), an intrarenal negative feedback between tubules and arterioles. TGF is initiated by an increase of NaCl delivery at the macula densa cells. The increased NaCl activates luminal Na-K-2Cl cotransporter (NKCC2) of the macula densa cells, which leads to activation of several intracellular processes followed by the production of paracrine signals that ultimately result in a constriction of the afferent arteriole and a tonic inhibition of single nephron glomerular filtration rate. Neuronal nitric oxide (NOS1) is highly expressed in the macula densa. NOS1β is the major splice variant and accounts for most of NO generation by the macula densa, which inhibits TGF response. Macula densa NOS1β-mediated modulation of TGF responses plays an essential role in control of sodium excretion, volume and electrolyte hemostasis, and blood pressure. In this article, we describe the mechanisms that regulate macula densa-derived NO and their effect on TGF response in physiologic and pathologic conditions. © 2023 American Physiological Society. Compr Physiol 13:4215-4229, 2023.

Critical Hypermagnesemia in Preeclamptic Women Under a Magnesium Sulfate Regimen: Incidence and Associated Risk Factors

Magnesium sulfate is used as prophylaxis and treatment of severe preeclampsia/eclampsia, albeit its safety and toxicity are a concern. We designed this study to estimate the incidence of critical hypermagnesemia in severely preeclamptic women under a magnesium sulfate regimen at 8 h following its administration and to identify the associated risk factors as the primary outcomes. Also, secondary outcomes were to compare baseline characteristics, laboratory findings, and maternal-neonatal complications stratified by the baseline serum magnesium (Mg²⁺) in those women, and to assess the degree of agreement between patellar reflex and serum Mg²⁺ concentration 8 h following magnesium sulfate administration. We conducted a retrospective study including severely preeclamptic women receiving magnesium sulfate from June 2016 to May 2021. We enrolled 429 women in the study. Two-hundred sixty-one (60.8%) of the included women developed critical hypermagnesemia. Preeclamptic women with high baseline serum Mg²⁺ concentration demonstrated significantly affected renal functions, hepatic transaminase activities, and low platelet count as well as more reported maternal complications compared to those with low baseline serum Mg². Multivariable logistic regression revealed that a lower gestational age, a higher uric acid concentration, and a higher baseline serum Mg²⁺ concentration were independently associated with an increased risk of critical hypermagnesemia. The agreement between deep tendon reflex assessment and serum Mg²⁺ concentration was slight although not significant. The maternal-neonatal outcomes were non-significant in women with critical hypermagnesemia. More vigilant monitoring through assessment of both serum Mg²⁺ concentration and deep tendon reflex should be considered especially in high-risk women.

Macula Densa NOS1β Modulates Renal Hemodynamics and Blood Pressure during Pregnancy: Role in Gestational Hypertension

BACKGROUND

Regulation of renal hemodynamics and BP via tubuloglomerular feedback (TGF) may be an important adaptive mechanism during pregnancy. Because the β-splice variant of nitric oxide synthase 1 (NOS1β) in the macula densa is a primary modulator of TGF, we evaluated its role in normal pregnancy and gestational hypertension in a mouse model. We hypothesized that pregnancy upregulates NOS1β in the macula densa, thus blunting TGF, allowing the GFR to increase and BP to decrease.

METHODS

We used sophisticated techniques, including microperfusion of juxtaglomerular apparatus in vitro, micropuncture of renal tubules in vivo, clearance kinetics of plasma FITC-sinistrin, and radiotelemetry BP monitoring, to determine the effects of normal pregnancy or reduced uterine perfusion pressure (RUPP) on macula densa NOS1β/NO levels, TGF responsiveness, GFR, and BP in wild-type and macula densa-specific NOS1 knockout (MD-NOS1KO) mice.

RESULTS

Macula densa NOS1β was upregulated during pregnancy, resulting in blunted TGF, increased GFR, and decreased BP. These pregnancy-induced changes in TGF and GFR were largely diminished, with a significant rise in BP, in MD-NOS1KO mice. In addition, RUPP resulted in a downregulation in macula densa NOS1β, enhanced TGF, decreased GFR, and hypertension. The superimposition of RUPP into MD-NOS1KO mice only caused a modest further alteration in TGF and its associated changes in GFR and BP. Finally, in African green monkeys, renal cortical NOS1β expression increased in normotensive pregnancies, but decreased in spontaneous gestational hypertensive pregnancies.

CONCLUSIONS

Macula densa NOS1β plays a critical role in the control of renal hemodynamics and BP during pregnancy.

Pre-eclampsia is associated with later kidney chronic disease and end-stage renal disease: Systematic review and meta-analysis of observational studies

OBJECTIVES

To assess whether there is a risk of kidney disease during the postpartum period of women who had preeclampsia (PE).

STUDY DESIGN

Observational trials were searched in the PubMed, Science Direct, Clinical trials, Cochrane, LILACS and Web of Science databases. The data extracted from the studies were systematized, and the risk of bias was evaluated for each of them. Meta-analyses were performed with studies that evaluated chronic kidney disease (CKD) and end-stage renal disease (ESRD), pooling the natural logarithms of the adjusted risk measures and the confidence intervals of each study in a random effects model.

RESULTS

Of the 4149 studies evaluated, 35 articles were included in the review, of which 3 of the CKD and 6 of the ESRD presented the necessary outcomes to compose the meta-analysis. A formal registration protocol was included in the PROSPERO database (number: CRD42019111821). There was a statistically significant difference between the development of CKD (hazard ratio (HR): 1.82, confidence interval to 95% (95% CI): 1.27-2.62, P < 0.01) and ESRD (HR: 3.01, confidence interval to 95% (95% CI): 1.92-4.70, P < 0.01) in postpartum women affected by PE.

CONCLUSIONS

PE was considered a risk factor for the onset of CKD and ESRD in the postpartum period. Thus, more research is needed to clarify the underlying mechanisms of this association, and to assist in determining the most appropriate and effective clinical conduct to prevent and/or treat such complications.

LPS Induces Preeclampsia-Like Phenotype in Rats and HTR8/SVneo Cells Dysfunction Through TLR4/p38 MAPK Pathway

Accumulating evidence has shown that preeclampsia (PE) was associated with an aberrant maternal-fetal inflammatory response. In the present study, we first found that in human PE placentas levels of toll-like receptor 4 (TLR4), phosphorylated p38 mitogen-activated protein kinase (p-p38 MAPK) and inflammatory cytokines IL-6 and MCP-1 were significantly upregulated. Next, we demonstrated a notable increase in systolic blood pressure (SBP) and proteinuria in lipopolysaccharide (LPS)-treated pregnant rats and concomitant high levels of TLR4 and p-p38 in these PE-like rat placentas, which led to aberrant overexpression of both IL-6 and MCP-1, as well as deficient trophoblast invasion and spiral artery (SA) remodeling, and these abnormalities were ameliorated by SB203580, a reported inhibitor of p38. In vitro we further confirmed that LPS triggered the activation of TLR4/p38 signaling pathway, which promoted trophoblast apoptosis and damaged trophoblastic invasion via downstream effectors IL-6 and MCP-1; these mutations were rectified by silencing this signaling pathway. These findings elaborated potential mechanisms that aberrant TLR4/p38 signaling might contribute to PE and LPS-induced PE-like symptom by damaging trophoblast invasion and SA remodeling via activating inflammatory cytokines including IL-6 and MCP-1.

Serous retinal detachment in preeclampsia and malignant hypertension

OBJECTIVES

To compare and evaluate the characteristics of hypertensive choroidopathy with serous retinal detachment in preeclampsia and malignant hypertension (HTN) and explore choroidal ischemia as a pathogenesis using multimodal imaging.

METHODS

A retrospective multicenter case series. Medical charts were reviewed. Clinical characteristics and multimodal imaging, including optical coherence tomography (OCT) and OCT angiography (OCTA), were evaluated.

RESULTS

Fifty-three eyes of 29 preeclampsia patients and 45 eyes of 24 HTN patients were included. There were no differences in age, follow-up duration, baseline visual acuity, central macular thickness (CMT), or subfoveal choroidal thickness (CT) between the two groups. Blood pressure parameters, including systolic blood pressure, diastolic blood pressure, and pulse rate, were significantly higher in the HTN group. After serous retinal detachment resolved, both CMT (p < 0.001) and CT (p = 0.003) decreased more in the preeclampsia group. Hypertensive retinopathy features, including hemorrhage, exudates, cotton-wool spots, and optic disc edema, were predominantly found in the HTN group (p = 0.001). Final visual acuity was better in the preeclampsia group than in the HTN group (p = 0.048). Poor visual prognostic factors included the presence of retinopathy features (p = 0.005) and retinal detachment in the macula (p = 0.017).

CONCLUSION

Choroidal circulation may be affected earlier than retinal circulation by elevated blood pressure, presumably because of anatomical differences and autoregulatory mechanisms in the retinal vasculature. Serous retinal detachment with hypertensive choroidopathy presented with choroidal thickening that decreased after resolution, but the residual flow defects observed in the choriocapillaris on OCTA confirmed the long-hypothesized notion that ischemia is a mechanism underlying hypertensive choroidopathy.

MIR146A rs2910164 (G/C) Polymorphism is Associated with Incidence of Preeclampsia in Gestational Diabetes Patients

Preeclampsia and gestational diabetes are common pregnancy disorders that may be interrelated. MIR146A rs2910164 (G/C) is a functional polymorphism that was associated with several diseases. This study aimed to investigate the frequency of rs2910164 polymorphism and its possible correlation with the incidence of preeclampsia in gestational diabetes patients. The study involved 250 pregnant women divided into 80 healthy control subjects, 85 gestational diabetes patients only, and 85 patients of gestational diabetes combined with preeclampsia. Systolic and diastolic blood pressures, urinary proteins, kidney and liver functions, glucose homeostasis parameters, and lipid profile were determined. Genotyping of the polymorphism was conducted by PCR-RFLP. The frequency of the minor C allele of rs2910164 polymorphism was significantly higher among patients of gestational diabetes combined with preeclampsia compared to the control group (p = 0.012) and the gestational diabetes group (p = 0.014). Patients of gestational diabetes and preeclampsia carrying CC genotype showed higher systolic and diastolic blood pressure, and increased urea, creatinine, urine protein, and dyslipidemia compared to the carriers of GG and GC genotypes. In conclusion, the results of the current study suggest that the rare CC genotype of MIR146A rs2910164 (G/C) polymorphism may be related to increased incidence of preeclampsia in gestational diabetes patients.

Role of endogenous digitalis-like factors in the clinical manifestations of severe preeclampsia: a sytematic review

Endogenous digitalis-like factor(s), originally proposed as a vasoconstrictor natriuretic hormone, was discovered in fetal and neonatal blood accidentally because it cross-reacts with antidigoxin antibodies (ADAs). Early studies using immunoassays with ADA identified the digoxin-like immuno-reactive factor(s) (EDLF) in maternal blood as well, and suggested it originated in the feto-placental unit. Mammalian digoxin-like factors have recently been identified as at least two classes of steroid compounds, plant derived ouabain (O), and several toad derived bufodienolides, most prominent being marinobufagenin (MBG). A synthetic pathway for MBG has been identified in mammalian placental tissue. Elevated maternal and fetal EDLF, O and MBG have been demonstrated in preeclampsia (PE), and inhibition of red cell membrane sodium, potassium ATPase (Na, K ATPase (NKA)) by EDLF is reversed by ADA fragments (ADA-FAB). Accordingly, maternal administration of a commercial ADA-antibody fragment (FAB) was tested in several anecdotal cases of PE, and two, small randomized, prospective, double-blind clinical trials. In the first randomized trial, ADA-FAB was administered post-partum, in the second antepartum. In the post-partum trial, ADA-FAB reduced use of antihypertensive drugs. In the second trial, there was no effect of ADA-FAB on blood pressure, but the fall in maternal creatinine clearance (CrCl) was prevented. In a secondary analysis using the pre-treatment maternal level of circulating Na, K ATPase (NKA) inhibitory activity (NKAI), ADA-FAB reduced the incidence of pulmonary edema and, unexpectedly, that of severe neonatal intraventricular hemorrhage (IVH). The fall in CrCl in patients given placebo was proportional to the circulating level of NKAI. The implications of these findings on the pathophysiology of the clinical manifestations PE are discussed, and a new model of the respective roles of placenta derived anti-angiogenic (AAG) factors (AAGFs) and EDLF is proposed.

Early pregnancy protein multiplex screening reflects circulating and urinary divergences associated with the development of preeclampsia

BACKGROUND

Preeclampsia, a pregnancy disorder characterized by hypertension and proteinuria, represents the leading cause of fetal and maternal morbidity and mortality in developing countries. The identification of novel and accurate biomarkers that are predictive of preeclampsia is necessary to improve the prognosis of patients with preeclampsia.

OBJECTIVE

To evaluate the preeclampsia predictive value of 34 angiogenic-related proteins.

METHODS

We performed a nested cohort case-control study of pregnant women. The profile of the 34 proteins was evaluated at 12, 16, and 20 gestational weeks (GWs), using urine/plasma from 16 women who developed preeclampsia and 20 normotensive pregnant controls by Bio-Plex Pro^TM Human Cancer Biomarker Panels 1 and 2.

RESULTS

The urine concentration of soluble epidermal growth factor receptor (sEGFR), hepatocyte growth factor (HGF), angiopoietin-2 (ANG-2), endoglin (ENG), soluble fas ligand (sFASL), interleukin 6 (IL-6), placental growth factor (PLGF), and vascular endothelial growth factor A (VEGF-A) at 12 GW, prolactin (PRL), ANG-2, transforming growth factor alpha (TGF-α), and VEGF-A at 16 GW, and soluble IL-6 receptor alpha (sIL-6Rα), ANG-2 and sFASL at 20 GW, were different between groups (p < 0.05). The concentration cut-off values calculated in this study for the mentioned proteins, predicted an increased risk to developing preeclampsia in a range of 3.8-29.8 times in the study population.

CONCLUSION

The proteins sEGFR, HGF, ANG-2, sFASL, IL-6, PLGF, VEGF-A, PRL, TGF-α FGF-b, sHER2/Neu sIL-6Rα, ENG, uPA, and insulin-like growth factor binding protein 1 (IGFBP-1), were predictive of the development of preeclampsia and their use as markers for this disease should be considered.

Environmental contaminants and preeclampsia: a systematic literature review

Preeclampsia is a medical condition specific to pregnancy characterized by high blood pressure and protein in the woman's urine, indicating kidney damage. It is one of the most serious reproductive conditions, posing substantial risks to the baby and potentially fatal for the mother. The causes of preeclampsia are largely unknown and environmental contaminants merit further investigation. The aim of this review was to determine the association between environmental chemical exposures and preeclampsia. PubMed was searched for articles examining a priori chemical exposures and preeclampsia through April 2018. Studies were included in our review if they included at least 10 cases, evaluated preeclampsia independent of gestational hypertension, and used either measured or modeled exposure assessments. Our review contained 28 investigations examining persistent organic pollutants (POP) (6 studies), drinking water contaminants (1 study), atmospheric pollutants (11 studies), metals and metalloids (6 studies), and other environmental contaminants (4 studies). There were an insufficient number of investigations on most chemicals to draw definitive conclusions, but strong evidence existed for an association between preeclampsia and cadmium (Cd). There is suggestive evidence for associations between nitrogen dioxide (NO₂), particulate matter (PM)_2.5, and traffic exposure with preeclampsia. There is evidence for an association between preeclampsia and Cd but insufficient literature to evaluate many other environmental chemicals. Additional studies using repeated measures, appropriate biological matrices, and mixtures methods are needed to expand this area of research and address the limitations of previous studies.

Is massive proteinuria associated with maternal and fetal morbidities in preeclampsia?

Objective

The aim of this study was to investigate whether massive proteinuria in preeclampsia is associated with maternal and fetal complications.

Methods

We retrospectively analyzed the clinical records of 233 patients who were diagnosed with preeclampsia. We divided the preeclamptic patients into three groups based on the amount of proteinuria: massive (≥5 g/24 hr), moderate (2 to 5 g/24 hr) and mild (<2 g/24 hr) proteinuria group. We analyzed the clinical characteristics and maternal and neonatal complications among three groups.

Results

Gestational age at diagnosis and delivery were lower in women with massive and moderate proteinuria group than women with mild proteinuria group (31.5±3.1 vs. 32.3±3.6 vs. 34.0±3.5 weeks, P<0.001 for gestational weeks at diagnosis; 34.6±3.6 vs. 35.1±4.1 vs. 36.9±4.0 weeks, P=0.001 for gestational age at delivery). In maternal complications, the incidences of pleural effusion and retinal detachment were significantly different among three groups (29.9% vs. 22.4% vs. 9.0%, P=0.004 for pleural effusion; 11.5% vs. 3.0% vs. 1.3%, P=0.009 for retinal detachment). Creatinine levels were higher and albumin levels were lower in the massive proteinuria group than in the moderate and mild groups. However, other maternal and neonatal complications were not significantly different among three groups.

Conclusion

Massive proteinuria might be associated with renal albumin excretion-related morbidity, such as pleural effusion, retinal detachment, and low serum albumin levels. Furthermore, it was associated with early-onset preeclampsia and early delivery.

Serum Cystatin C in Pregnancies With Normal and Restricted Fetal Growth

The objective of this study was to investigate circulating levels of cystatin C (an important endogenous marker of renal function) in mothers, fetuses, and neonates from intrauterine growth-restricted (IUGR; characterized by impaired nephrogenesis) and appropriate-for-gestational-age (AGA) pregnancies. Serum cystatin C levels were measured by enzyme immunoassay in 40 parturients and their 20 IUGR (<or=3rd customized centile, due to gestational pathology) and 20 AGA fetuses and neonates on postnatal day 1 (N1) and 4 (N4). Comparatively, creatinine and urea concentrations were determined in the same samples. Fetal cystatin C levels were higher in the AGA than the IUGR group (P = .001). In both groups, maternal cystatin C levels were lower than fetal (P < .001), N1 (P < .001), and N4 (P < .001) levels. Fetal levels were higher than N1 (P < .001) and N4 (P < .001), and N1 levels were higher than N4 (P = .007) ones. In both groups, no correlation existed between maternal and fetal levels, but positive correlations were found between cystatin C, creatinine, and urea levels in maternal and neonatal samples (in all cases, r >or= 0.376 and P <or= .045). Cystatin C levels did not correlate with gestational age and did not differ between males and females. Fetal cystatin C serum levels are lower in the IUGR group, significantly decrease after birth, and do not correlate with maternal levels in both groups. In addition, serum cystatin C levels positively correlate with respective creatinine and urea levels in the perinatal period.

Predictors of Impaired Postpartum Renal Function in Women after Preeclampsia: Results of a Prospective Single Center Study

Objective. The purpose of this prospective study was to investigate the predictive value of single prepartum findings combined with serum biomarkers sFlt-1 (soluble fms-like tyrosine kinase-1) and PlGF (placental growth factor) indicating severity of preeclampsia (PE) for occurrence and extent of impaired postpartum kidney function. Study Design. In this prospective, single center study 44 PE patients were compared to 39 healthy controls (similar in age and gestational age with singleton pregnancy) evaluated at time of delivery and at 6 months and 12 months postpartum. p values below 0.05 are considered statistically significant. Results. The majority of the PE patients had persistence of proteinuria (>120 mg/L after delivery) 6 months (p = 0.02) and 12 months postpartum (p < 0.0001) compared to controls. Also reduced GFR (glomerular filtration rate) persisted up to 6 months postpartum in PE patients compared to controls (p < 0.001). Prepartum sFlt-1 levels indeed correlated with impaired renal function parameters. Conclusion. A significant proportion of our PE patients had lower GFR levels and persistent proteinuria up to 12 months postpartum. Prepartum sFlt-1 is a trend-setting marker for impaired renal function postpartum, but it is not sufficient enough to predict renal impairment after PE. An evaluation of 24-month follow-up data is scheduled.

Novel Electrocardiographic Patterns for the Prediction of Hypertensive Disorders of Pregnancy--From Pathophysiology to Practical Implications

Hypertensive disorders of pregnancy are a major cause of poor outcome, including placental abruption, organ failure, cerebrovascular accident and disseminated intravascular coagulation. These disorders are associated with increased fetal risk of intrauterine growth restriction, intrauterine death and prematurity. Electrocardiography (ECG) recently emerged as a useful tool to evaluate cardiovascular complications during pregnancy. Specifically, left atrial abnormalities detected by standard ECG are associated with a fourfold increased risk of developing hypertensive disorders during pregnancy. The mechanisms linking left atrial abnormality on ECG with hypertensive disorders are still elusive. Several mechanisms, possibly reflected by abnormal left atrial activation on ECG, has been suggested. These include increased reactivity to angiotensin II and up-regulation of angiotensin type 1 receptors, with activation of autoantibodies targeting these receptors.

Salinity in drinking water and the risk of (pre)eclampsia and gestational hypertension in coastal Bangladesh: a case-control study

Background

Hypertensive disorders in pregnancy are among the leading causes of maternal and perinatal death in low-income countries, but the aetiology remains unclear. We investigated the relationship between salinity in drinking water and the risk of (pre)eclampsia and gestational hypertension in a coastal community.

Methods

A population-based case-control study was conducted in Dacope, Bangladesh among 202 pregnant women with (pre)eclampsia or gestational hypertension, enrolled from the community served by the Upazilla Health Complex, Dacope and 1,006 matched controls from the same area. Epidemiological and clinical data were obtained from all participants. Urinary sodium and sodium levels in drinking water were measured. Logistic regression was used to calculate odds ratios, and 95% confidence intervals.

Findings

Drinking water sources had exceptionally high sodium levels (mean 516.6 mg/L, S.D 524.2). Women consuming tube-well (groundwater) were at a higher disease risk than rainwater users (p<0.001). Adjusted risks for (pre)eclampsia and gestational hypertension considered together increased in a dose-response manner for increasing sodium concentrations (300.01–600 mg/L, 600.1–900 mg/L, >900.01 mg/L, compared to <300 mg/L) in drinking water (ORs 3.30 [95% CI 2.00–5.51], 4.40 [2.70–7.25] and 5.48 [3.30–9.11] (p-trend<0.001). Significant associations were seen for both (pre)eclampsia and gestational hypertension separately.

Interpretation

Salinity in drinking water is associated with increased risk of (pre)eclampsia and gestational hypertension in this population. Given that coastal populations in countries such as Bangladesh are confronted with high salinity exposure, which is predicted to further increase as a result of sea level rise and other environmental influences, it is imperative to develop and evaluate affordable approaches to providing water with low salt content.

The renal circulation in normal pregnancy and preeclampsia: is there a place for relaxin?

During the first trimester of human pregnancy, the maternal systemic circulation undergoes remarkable vasodilation. The kidneys participate in this vasodilatory response resulting in marked increases in renal plasma flow (RPF) and glomerular filtration rate (GFR). Comparable circulatory adaptations are observed in conscious gravid rats. Administration of the corpus luteal hormone relaxin (RLN) to nonpregnant rats and humans elicits vasodilatory changes like those of pregnancy. Systemic and renal vasodilation are compromised in midterm pregnant rats by neutralization or elimination of circulating RLN and in women conceiving with donor eggs who lack a corpus luteum and circulating RLN. Although RLN exerts both rapid (minutes) and sustained (hours to days) vasodilatory actions through different molecular mechanisms, a final common pathway is endothelial nitric oxide. In preeclampsia (PE), maternal systemic and renal vasoconstriction leads to hypertension and modest reduction in GFR exceeding that of RPF. Elevated level of circulating soluble vascular endothelial growth factor receptor-1 arising from the placenta is implicated in the hypertension and disruption of glomerular fenestrae and barrier function, the former causing reduced Kf and the latter proteinuria. Additional pathogenic factors are discussed. Last, potential clinical ramifications include RLN replacement in women conceiving with donor eggs and its therapeutic use in PE. Another goal has been to apply knowledge gained from investigating circulatory adaptations in pregnancy toward identifying and developing novel therapeutic strategies for renal and cardiovascular disease in the nonpregnant population. So far, one candidate to emerge is RLN and its potential therapeutic use in heart failure.

The renin-angiotensin-aldosterone system in pre-eclampsia: the delicate balance between good and bad

Pregnancy demands major changes of the cardiovascular system, and this involves, among others, activation of the RAAS (renin-angiotensin-aldosterone system), allowing an aldosterone-dependent increase in volume. Remarkably, a relative resistance to the pressor response of AngII (angiotensin II) develops simultaneously to prevent the increase in blood pressure that would normally accompany RAAS activation. The increase in volume, the degree of RAAS activation and the diminished pressor response to AngII are less pronounced in pre-eclampsia. However, animal models displaying excessive RAAS activation also result in a pre-eclampsia-like syndrome, and the aldosterone/renin ratio is elevated in pre-eclampsia compared with a normal pregnancy. New insights into the pathogenesis of pre-eclampsia have revealed a major role for VEGF (vascular endothelial growth factor), VEGF-inactivating sFlt-1 (soluble fms-like tyrosine kinase-1) and AT1 (angiotensin II type 1) receptor autoantibodies. The last mentioned activate AT(1) receptors, thereby potentially suppressing circulating renin and aldosterone. VEGF, both directly and indirectly (by increasing capillary density), affects adrenal aldosterone synthesis. The present review summarizes all of the recent findings regarding RAAS regulation in pre-eclampsia compared with normal pregnancy, concluding that factors such as sFlt-1 and AT(1) receptor autoantibodies disturb the delicate balance that normally results in a volume increase and a diminished vasoconstrictor response to AngII in pregnant women. It is possible that there are non-parallel changes in the circulating and renal RAAS in pre-eclampsia, which are potentially reflected by the urinary levels of renin.

Adverse pregnancy outcomes in hypertensive patients: predictive value of protein concentration versus total protein

OBJECTIVES

To compare the predictive value of protein concentration in a twenty-four hour urine collection to the conventional total protein in a twenty-four hour urine collection for adverse pregnancy outcomes in hypertensive patients.

STUDY DESIGN

Retrospective cohort study. Hypertensive patients ≥20 weeks estimated gestational age (EGA) who completed twenty-four hour urine protein collections were identified; antepartum and delivery data were examined. For study patients who met criteria for adverse pregnancy outcome, multi-variable analysis was performed and summary receiver operating characteristic (ROC) curves were generated for each model (total protein compared to protein concentration). The models were compared by analyzing the area under the curve (AUC).

RESULTS

A total of 150 patients were analyzed. Mean gestational age at delivery was 36.7 weeks. Analysis of the ROC curves showed no significant difference between the models (AUCs of 0.668 versus 0.656, p = 0.715). Optimal thresholds were 299.2 mg for total protein and 0.1 mg/ml for protein concentration.

CONCLUSION

A protein concentration of 0.1 mg/ml on a twenty-four hour urine collection appears equivalent to the traditional 300 mg total protein. If confirmed by prospective studies, this finding would be clinically important in cases where collections fall short of the 300 mg threshold but exceed the 0.1 mg/ml concentration.

Positive correlation between serum levels of adiponectin and homocysteine in pre-eclampsia

AIM

The aims of the present study were to assess the correlation between homocysteine and adiponectin and the homocysteine-to-adiponectin ratio in pre-eclampsia compared with normal pregnant women.

MATERIALS AND METHODS

The study population consisted of 30 women with pre-eclampsia and 30 normal pregnant women. Serum levels of total adiponectin and total homocysteine were assessed using commercially available enzyme-linked immunosorbent assay methods. Data are presented as median.

RESULTS

Serum levels of total adiponectin correlated directly with total homocysteine in both pre-eclampsia (r = 0.48, P = 0.01) and normal pregnancy (r = 0.68, P = 0.001). The homocysteine-to-adiponectin ratio was increased significantly in pre-eclampsia compared with normal pregnancy (0.90 vs 0.70, P = 0.03). Compared with normal pregnancy, women with severe pre-eclampsia showed significant increase in total adiponectin (14.29 vs 10.24, P = 0.01), total homocysteine (13.80 vs 7.25, P = 0.000) and homocysteine-to-adiponectin ratio (0.92 vs 0.70, P = 0.02). Women with mild pre-eclampsia had higher values of total adiponectin (16.19 vs 10.24, P = 0.000) and total homocysteine (13.11 vs 7.25, P = 0.000) compared with normal pregnancy. No significant differences were observed between mild and severe pre-eclampsia.

CONCLUSION

The present study showed a positive association between adiponectin and homocysteine in pre-eclampsia. The homocysteine-to-adiponectin ratio may be an informative biomarker for the disease diagnosis and therapeutic monitoring.

A comprehensive review of hypertension in pregnancy

Hypertension is the most common medical disorder encountered during pregnancy. Hypertensive disorders are one of the major causes of pregnancy-related maternal deaths in the United States. We will present a comprehensive update of the literature pertinent to hypertension in pregnancy. The paper begins by defining and classifying hypertensive disorders in pregnancy. The normal vascular and renal physiological changes which occur during pregnancy are detailed. We will summarize the intriguing aspects of pathophysiology of preeclampsia, emphasizing on recent advances in this field. The existing diagnostic tools and the tests which have been proposed for screening preeclampsia are comprehensively described. We also highlight the short- and long-term implications of preeclampsia. Finally, we review the current management guidelines, goals of treatment and describe the potential risks and benefits associated with various antihypertensive drug classes. Preeclampsia still remains an enigma, and the present management focuses on monitoring and treatment of its manifestations. We are hopeful that this in depth critique will stimulate the blossoming research in the field and assist practitioners to identify women at risk and more effectively treat affected individuals.

The management challenges of non-preeclampsia-related nephrotic syndrome in pregnancy

Nephrotic syndrome in a pregnant woman may be challenging, especially when the onset is early in pregnancy or with severe manifestations. Preeclampsia is the most common cause of nephrotic syndrome in pregnancy; however, this review will focus on the management of other renal causes. The aim of this pragmatic review is to address clinical issues that clinicians looking after women with nephrotic syndrome may encounter during pregnancy and the postpartum period. First, we discuss some general issues regarding nephrotic syndrome and its impact on maternal and fetal outcomes in pregnancy, and then we review the maternal management of nephrotic syndrome in pregnancy and during the postpartum period.

Interpreting abnormal proteinuria in pregnancy: the need for a more pathophysiological approach

This review and opinion article focuses on the definitions and meanings of abnormal protein excretion in pregnancy, asking the following questions: Are our tests to determine abnormal proteinuria adequately performed? Are current guidelines for diagnosis of excessive proteinuria, especially when used to identify preeclampsia, supported by adequate data? Can the magnitude of proteinuria be used as a reliable clinical biomarker of the gravity of preeclampsia? Should timed urine collections, primarily 24-hour excretions, be supplanted by the urine protein/creatinine ratio in clinical practice? The answers to most of these questions are: We are not sure, or some guidelines are poorly supported by data and may prove erroneous. We suggest a more physiologic approach to assessment of proteinuria and believe that if clinicians and investigators looked at proteinuria in terms of how the kidney handles protein in health and disease it would lead to a more rational and evidence-based approach to proteinuria in pregnancy. Finally, we recommend that current cutoff for abnormal proteinuria be used to diagnose preeclampsia, but the level of proteinuria should not guide management. Other variables, such as status of blood pressure control, evidence of increasing organ damage in the liver and hematological systems, evidence of falling glomerular filtration rate, and signs of neurological involvement, are more reliable indicators of severity of preeclampsia.

Fractional excretion of tumor necrosis factor-alpha in women with severe preeclampsia

OBJECTIVE

Proinflammatory cytokines of placental or systemic origin are thought to play a central role in the pathophysiology of preeclampsia. We sought to estimate the fractional excretion of tumor necrosis factor (TNF)-alpha in relationship to proteinuria in women with severe preeclampsia.

METHODS

In a cross-sectional study, we evaluated the serum and urine levels of TNF-alpha in 45 women diagnosed with severe preeclampsia (mean+/-standard error of the mean, gestational age 29.1+/-0.5 weeks). Forty-five healthy pregnant women matched for parity, maternal age, and gestational age at recruitment (30.1+/-0.4 weeks) made up the control group. Urinary concentrations were normalized to creatinine. The fractional excretion of TNF-alpha was interpreted in relationship to that of total proteins and soluble fms-like tyrosine kinase-1 (sFlt-1).

RESULTS

We found that the women with preeclampsia had significantly higher serum TNF-alpha concentrations compared with the women in the control group (mean+/-standard error of the mean, preeclampsia: 1.39+/-0.09 versus control: 0.93+/-0.07 pg/mL, P<.001). In contrast, urinary levels of TNF-alpha were significantly decreased in the women with preeclampsia compared with the healthy women (median [interquartile range], preeclampsia: 0.26 [0.10-0.91] versus control: 0.58 [0.21-1.29] pg/mg creatinine, P=.003), even though the hypertensive women had higher levels of proteinuria. In contrast to sFlt-1, urinary TNF-alpha did not correlate with the degree of proteinuria. Additionally, in preeclampsia, the fractional excretion of TNF-alpha was significantly lower (preeclampsia: 1.92% [0.46-4.20] versus control: 7.2% [2.44-12.07], P<.001).

CONCLUSION

The fractional excretion of TNF-alpha is significantly reduced in women with severe preeclampsia despite proteinuria. The decreased clearance and altered renal excretion of this cytokine may contribute to the exaggerated inflammatory response observed in preeclampsia.

LEVEL OF EVIDENCE

II.

Anatomic and Functional Changes of the Upper Urinary Tract During Pregnancy

An appreciation of the maternal physiologic adaptations that occur in the renal system during pregnancy is fundamental to the understanding and proper clinical management of normal pregnancy, renal disorders in the gravid patient, and pregnancy-specific conditions such as pre-eclampsia. In this article, the authors first address the anatomic changes that occur in the upper urinary tract in normal pregnancy, followed by the dramatic alterations in maternal renal hemodynamics and glomerular filtration. They also briefly discuss renal handling of various substrates in pregnancy, including protein, uric acid, and glucose. An understanding of these changes is important and relevant to the clinician caring for pregnant women.

Renal and vascular function in women with previous preeclampsia: A comparison of low- and high-degree proteinuria

The degree of proteinuria during preeclampsia has been considered to be a marker of severity of the disease and of endothelial dysfunction. The aim of the study was to assess whether the degree of proteinuria in preeclamptic pregnancy is related to impairment of vascular dilatation and/or kidney function years after the index pregnancy. Thirty women with a history of severe preeclampsia divided into low (n=8, dU-prot <5 g/day) and high (n=22, dU-prot >/=5 g/day) proteinuric groups and 21 women with previous normotensive pregnancy were studied 5-6 years after index pregnancy. Renal function and blood pressure were assessed together with venous occlusion plethysmography, where changes in brachial artery blood flow, induced by intra-arterial infusions of an endothelium-independent (sodium nitroprusside) and an endothelium-dependent (acetylcholine) vasodilator, were measured. The results showed similar renal function in all groups. There was no difference in vasodilation between preeclamptic groups and controls or correlation between degree of proteinuria during index pregnancy and present vasodilation. We conclude that the degree of proteinuria during preeclampsia does not predict vascular dilatation or renal function 5-6 years after preeclamptic pregnancy.

Total and free tissue factor pathway inhibitor in pregnancy hypertension

OBJECTIVE

To clarify the role played by tissue factor pathway inhibitor (TFPI) in pregnancy hypertension.

METHODS

Using enzyme-linked immunosorbent assays, hemostatic measurements were obtained for women with pre-eclampsia (n=51), nonproteinuric hypertension of pregnancy (n=62), postpartum pre-eclampsia 24 h after childbirth (n=31), and no hypertension (healthy pregnant controls, n=100).

RESULTS

There was a significant increase in circulating free TFPI levels in women with pre-eclampsia (9.7+/-6.2 ng/mL) or nonproteinuric hypertension of pregnancy (8.3+/-5.3 ng/mL) compared with healthy controls (5.3+/-2.1 ng/mL). In women with pre-eclampsia the levels remained elevated after placental delivery (10.6+/-4.0 ng/mL). Free protein S levels were significantly higher in women with pre-eclampsia (40.0%+/-10.7%), nonproteinuric hypertension of pregnancy (37.1%+/-12.5%), or postpartum pre-eclampsia (39.3%+/-9.1%) than in healthy pregnant controls (32.2%+/-8.5%).

CONCLUSION

Increased levels of the physiologically active free forms of TFPI and free protein S, 2 coagulation inhibitors, may protect women with pregnancy-induced hypertension from the risks of hemostatic activation.

Mechanisms of Disease: pre-eclampsia

Pre-eclampsia, a syndrome of pregnant women, is one of the leading causes of maternal and fetal morbidity and mortality. Despite active research, the etiology of this disorder remains an enigma. Recent work has, however, provided promising explanations for the causation of the disorder and some of its phenotypes. Evidence indicates that the symptoms of hypertension and proteinuria, upon which the diagnosis of pre-eclampsia is based, have several underlying causes. Nevertheless, the treatment of pre-eclampsia has not changed significantly in over 50 years. This review describes the most recent insights into the pathophysiology of pre-eclampsia from both basic and clinical research, and attempts to provide a unifying hypothesis to reconcile the abnormalities at the feto-placental level and the clinical features of the maternal syndrome. The novel findings outlined in this review provide a rationale for potential future prophylactic and therapeutic interventions for pre-eclampsia.