Persistent urinary podocyte loss following preeclampsia may reflect subclinical renal injury

Urinary podocyte markers of disease activity, therapeutic efficacy, and long-term outcomes in acute and chronic kidney diseases

A critical degree of podocyte depletion causes glomerulosclerosis, and persistent podocyte loss in glomerular diseases drives the progression to end-stage kidney disease. The extent of podocyte injury at a point in time can be histologically assessed by measuring podocyte number, size, and density ("Biopsy podometrics"). However, repeated invasive renal biopsies are associated with increased risk and cost. A noninvasive method for assessing podocyte injury and depletion is required. Albuminuria and proteinuria do not always correlate with disease activity. Podocytes are located on the urinary space side of the glomerular basement membrane, and as they undergo stress or detach, their products can be identified in urine. This raises the possibility that urinary podocyte products can serve as clinically useful markers for monitoring glomerular disease activity and progression ("Urinary podometrics"). We previously reported that urinary sediment podocyte mRNA reflects disease activity in both animal models and human glomerular diseases. This includes diabetes and hypertension which together account for 60% of new-onset dialysis induction patients. Improving approaches to preventing progression is an urgent priority for the renal community. Sufficient evidence now exists to indicate that monitoring urinary podocyte markers could serve as a useful adjunctive strategy for determining the level of current disease activity and response to therapy in progressive glomerular diseases.

Relationship between parity and the prevalence of chronic kidney disease in Japan considering hypertensive disorders of pregnancy and body mass index

BACKGROUND

Global studies exploring the relationship between parity and chronic kidney disease (CKD) are scarce. Furthermore, no study has examined the relationship between parity and CKD in Japan. Therefore, this study aimed to examine the relationship between parity and the prevalence of CKD in a Japanese population, considering the clinical history of hypertensive disorders of pregnancy (HDP) and current body mass index (BMI) based on menopausal status.

METHODS

This cross-sectional study included 26,945 Japanese multiparous women (5,006 premenopausal and 21,939 postmenopausal women) and 3,247 nulliparous women (1,599 premenopausal and 1,648 postmenopausal women). Participants were divided into two groups based on their menopausal status (premenopausal and postmenopausal women). The relationship between parity and the prevalence of CKD was evaluated using a multiple logistic regression model adjusted for several covariates, including a clinical history of HDP and current BMI.

RESULTS

The relationship between parity and the prevalence of CKD was not statistically significant in either premenopausal or postmenopausal multiparous women. A clinical history of HDP was significantly associated with an increased risk of CKD in premenopausal and postmenopausal multiparous women. However, the relationship between a clinical history of HDP and CKD in premenopausal women was weakened after adjusting for current BMI. Furthermore, the current BMI was significantly associated with an increased risk of CKD in both premenopausal and postmenopausal women.

CONCLUSIONS

Parity is not significantly associated with the prevalence of CKD in premenopausal and postmenopausal multiparous women. A clinical history of HDP is a risk factor for CKD in both premenopausal and postmenopausal women. Current BMI is also associated with an increased risk of CKD in premenopausal and postmenopausal women. Therefore, continuous surveillance and preventive measures against CKD should be provided to women with a clinical history of HDP. In addition, maintaining an appropriate body weight is beneficial in reducing the risk of CKD.

Impact of Aging and Cellular Senescence in the Pathophysiology of Preeclampsia

The incidence of hypertensive disorders of pregnancy is increasing, which may be due to several factors, including an increased age at pregnancy and more comorbid health conditions during reproductive years. Preeclampsia, the most severe hypertensive disorder of pregnancy, has been associated with an increased risk of future disease, including cardiovascular and kidney diseases. Cellular senescence, the process of cell cycle arrest in response to many physiologic and maladaptive stimuli, may play an important role in the pathogenesis of preeclampsia and provide a mechanistic link to future disease. In this article, we will discuss the pathophysiology of preeclampsia, the many mechanisms of cellular senescence, evidence for the involvement of senescence in the development of preeclampsia, as well as evidence that cellular senescence may link preeclampsia to the risk of future disease. Lastly, we will explore how a better understanding of the role of cellular senescence in preeclampsia may lead to therapeutic trials. © 2023 American Physiological Society. Compr Physiol 13:5077-5114, 2023.

Increased urinary albumin leakage is related to injuries of glomerular glycocalyx and podocytes, and associated with tubular dysfunction in preeclampsia

OBJECTIVE

The pathogenesis of preeclampsia (PE) is known to be endothelial cell damage; however, the existence of dysfunction in glomerular endothelial glycocalyx, podocytes and tubules remains unclear. The glomerular endothelial glycocalyx, basement membrane, podocytes, and tubules are permeability barriers against albumin excretion. This study aimed to assess the relationship between urinary albumin leakage and injuries of the glomerular endothelial glycocalyx, podocytes, and tubules in patients with PE.

METHODS

A total of 81 women with uncomplicated pregnancies (control, n = 22), PE (PE, n = 36), or gestational hypertension (GH) (GH, n = 23) were enrolled. We assessed urinary albumin and serum hyaluronan for glycocalyx injuries, podocalyxin for podocytes injuries, and urinary N-acetyl-β-d-glucosaminidase (NAG) and liver-type fatty acid-binding protein (l-FABP) for renal tubular dysfunctions.

RESULTS

The serum hyaluronan and the urinary podocalyxin levels were higher in the PE and GH groups. The urinary NAG and l-FABP levels were higher in the PE group. Urinary NAG and l-FABP levels positively correlated with urinary albumin excretion.

CONCLUSIONS

Our findings suggest that increased urinary albumin leakage is related to injuries of the glycocalyx and podocytes, and associated with tubular dysfunction in pregnant women with PE. The clinical trial described in this paper was registered at the UMIN Clinical Trials Registry under registration number UMIN000047875. URL of registration: https://centre6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000054437.

Angiotensin II type 1 receptor agonistic autoantibody blockade improves postpartum hypertension and cardiac mitochondrial function in rat model of preeclampsia

Women with preeclampsia (PE) have a greater risk of developing hypertension, cardiovascular disease (CVD), and renal disease later in life. Angiotensin II type I receptor agonistic autoantibodies (AT1-AAs) are elevated in women with PE during pregnancy and up to 2-year postpartum (PP), and in the reduced uterine perfusion pressure (RUPP) rat model of PE. Blockade of AT1-AA with a specific 7 amino acid peptide binding sequence (‘n7AAc’) improves pathophysiology observed in RUPP rats; however, the long-term effects of AT1-AA inhibition in PP is unknown. Pregnant Sprague Dawley rats were divided into three groups: normal pregnant (NP) (n = 16), RUPP (n = 15), and RUPP + ‘n7AAc’ (n = 16). Gestational day 14, RUPP surgery was performed and ‘n7AAc’ (144 μg/day) administered via osmotic minipump. At 10-week PP, mean arterial pressure (MAP), renal glomerular filtration rate (GFR) and cardiac functions, and cardiac mitochondria function were assessed. MAP was elevated PP in RUPP vs. NP (126 ± 4 vs. 116 ± 3 mmHg, p < 0.05), but was normalized in in RUPP + ‘n7AAc’ (109 ± 3 mmHg) vs. RUPP (p < 0.05). PP heart size was reduced by RUPP + ’n7AAc’ vs. RUPP rats (p < 0.05). Complex IV protein abundance and enzymatic activity, along with glutamate/malate-driven respiration (complexes I, III, and IV), were reduced in the heart of RUPP vs. NP rats which was prevented with ‘n7AAc’. AT1-AA inhibition during pregnancy not only improves blood pressure and pathophysiology of PE in rats during pregnancy, but also long-term changes in blood pressure, cardiac hypertrophy, and cardiac mitochondrial function PP.

Hypertensive Disorders of Pregnancy

Hypertensive disorders of pregnancy are increasing in incidence and are major causes of maternal morbidity and mortality both in the United States and worldwide. An understanding of these diseases is essential for the practicing nephrologist, as preexisting kidney disease is an important risk factor. In addition, the development of hypertensive disorders of pregnancy has important implications for long-term risk of kidney disease and cardiovascular disease. The definition and diagnostic criteria has changed in recent years as our understanding of the disease entity has progressed. Currently, proteinuria is no longer a necessary diagnostic feature of preeclampsia. Preeclampsia and gestational hypertension may develop through multiple different mechanisms. Current research suggests contributions of both placental factors and maternal factors contribute to the disease and represent different phenotypic presentations of preeclampsia.

Preeclampsia and Kidney Disease: Deciphering Cause and Effect

PURPOSE OF REVIEW

Preeclampsia and chronic kidney disease have a complex, bidirectional relationship. Women with kidney disease, with even mild reductions in glomerular filtrate rate, have an increased risk of developing preeclampsia. Preeclampsia, in turn, has been implicated in the subsequent development of albuminuria, chronic kidney disease, and end-stage kidney disease. We will discuss observational evidence and mechanisms linking the two disease processes.

RECENT FINDINGS

Preeclampsia is characterized by an imbalance in angiogenic factors that causes systemic endothelial dysfunction. Chronic kidney disease may predispose to the development of preeclampsia due to comorbid conditions, such as hypertension, but is also associated with impaired glycocalyx integrity and alterations in the complement and renin-angiotensin-aldosterone systems. Preeclampsia may lead to kidney disease by causing acute kidney injury, endothelial damage, and podocyte loss. Preeclampsia may be an important sex-specific risk factor for chronic kidney disease. Understanding how chronic kidney disease increases the risk of preeclampsia from a mechanistic standpoint may open the door to future biomarkers and therapeutics for all women.

Cystatin C as an indicator of renal damage in pre-eclampsia

OBJECTIVE

To assess the predictive abilities of serum and urinary cystatin C levels for glomerular lesions in pregnant women with pre-eclampsia.

METHODS

In this study, kidney function markers were compared between38 pregnant women with pre-eclampsia and 22 healthy pregnant women.

RESULTS

The serum and urine levels of cystatin C and urea were significantly higher in the pre-eclampsia group than in the control group. Receiver operating characteristic curve analysis demonstrated that the serum cystatin C level (91.7%) had a superior diagnostic accuracy for pre-eclampsia than the other markers.

CONCLUSION

Serum cystatin C level maybe a significant marker of pre-eclampsia.

Preeclampsia and risk of end stage kidney disease: A Swedish nationwide cohort study

BACKGROUND

Preeclampsia has been suggested to increase the risk of end-stage kidney disease (ESKD); however, most studies were unable to adjust for potential confounders including pre-existing comorbidities such as renal disease and cardiovascular disease (CVD). We aimed to examine the association between preeclampsia and the risk of ESKD in healthy women, while taking into account pre-existing comorbidity and potential confounders.

METHODS AND FINDINGS

Using data from the Swedish Medical Birth Register (MBR), women who had singleton live births in Sweden between 1982 and 2012, including those who had preeclampsia, were identified. Women with a diagnosis of chronic kidney disease (CKD), CVD, hypertension, or diabetes prior to the first pregnancy were excluded. The outcome was a diagnosis of ESKD, identified from the Swedish Renal Registry (SRR) from January 1, 1991, onwards along with the specified cause of renal disease. We conducted Cox proportional hazards regression analysis to examine the association between preeclampsia and ESKD adjusting for several potential confounders: maternal age, body mass index (BMI), education, native country, and smoking. This analysis accounts for differential follow-up among women because women had different lengths of follow-up time. We performed subgroup analyses according to preterm preeclampsia, small for gestational age (SGA), and women who had 2 pregnancies with preeclampsia in both. The cohort consisted of 1,366,441 healthy women who had 2,665,320 singleton live births in Sweden between 1982 and 2012. At the first pregnancy, women's mean (SD) age and BMI were 27.8 (5.13) and 23.4 (4.03), respectively, 15.2% were smokers, and 80.7% were native Swedish. The overall median (interquartile range [IQR]) follow-up was 7.4 years (3.2-17.4) and 16.4 years (10.3-22.0) among women with ESKD diagnosis. During the study period, 67,273 (4.9%) women having 74,648 (2.8% of all pregnancies) singleton live births had preeclampsia, and 410 women developed ESKD with an incidence rate of 1.85 per 100,000 person-years. There was an association between preeclampsia and ESKD in the unadjusted analysis (hazard ratio [HR] = 4.99, 95% confidence interval [CI] 3.93-6.33; p < 0.001), which remained in the extensively adjusted (HR = 4.96, 95% CI 3.89-6.32, p < 0.001) models. Women who had preterm preeclampsia (adjusted HR = 9.19; 95% CI 5.16-15.61, p < 0.001) and women who had preeclampsia in 2 pregnancies (adjusted HR = 7.13, 95% CI 3.12-16.31, p < 0.001) had the highest risk of ESKD compared with women with no preeclampsia. Considering this was an observational cohort study, and although we accounted for several potential confounders, residual confounding cannot be ruled out.

CONCLUSIONS

The present findings suggest that women with preeclampsia and no major comorbidities before their first pregnancy are at a 5-fold increased risk of ESKD compared with parous women with no preeclampsia; however, the absolute risk of ESKD among women with preeclampsia remains small. Preeclampsia should be considered as an important risk factor for subsequent ESKD. Whether screening and/or preventive strategies will reduce the risk of ESKD in women with adverse pregnancy outcomes is worthy of further investigation.

An evidence-based approach to pre-pregnancy counselling for patients with systemic lupus erythematosus

Patients with SLE are often young females of childbearing age and a pregnancy wish in this patient group is common. However, SLE patients are at high risk for adverse pregnancy outcomes that require adequate guidance. It is widely acknowledged that pre-pregnancy counselling is the pivotal first step in the management of SLE patients with a wish to become pregnant. Next, management of these patients is usually multidisciplinary and often requires specific expertise from the different physicians involved. Very recently a EULAR recommendation was published emphasizing the need for adequate preconception counselling and risk stratification. Therefore the present review specifically addresses the issue of pre-pregnancy counselling for SLE patients with an evidence-based approach. The review summarizes data retrieved from recently published, high-quality cohort studies that have contributed to a better understanding and estimation of pregnancy-related risks for SLE patients. The present review categorizes risks from a patient-oriented point of view, that is, the influence of pregnancy on SLE, of SLE on pregnancy, of SLE on the foetus/neonate and of SLE-related medication. Lastly, pre-pregnancy counselling of SLE patients with additional secondary APS is reviewed. Collectively these data can guide clinicians to formulate appropriate preventive strategies and patient-tailored monitoring plans during pre-pregnancy counselling of SLE patients.

Risk of cardiovascular disease, end-stage renal disease, and stroke in postpartum women and their fetuses after a hypertensive pregnancy

Women with hypertensive pregnancy complications are at greater risk of developing cardiovascular disease (CVD), metabolic diseases, stroke, and end-stage renal disease (ESRD) later in life. Pregnancy complications affect not only the mother's long-term health but also the health of the fetus immediately after delivery and into adulthood. The health of the fetus until adulthood can be influenced by developmental programming, in which the fetus is exposed to insults that will ultimately affect the growth of the offspring and increase the offspring's risk of developing hypertension, coronary heart disease, metabolic disease, and chronic kidney disease in adulthood. Preeclampsia, the onset of hypertension during pregnancy, is one of the major risk factors for the development of renal disease, cerebral disease, and CVD in the mother. Women with preeclampsia are at a 5-12-fold increased risk of developing ESRD, 2-fold increased risk of stroke, and 2-fold increased risk of developing CVD later in life. In this review article, we discuss 1) preeclampsia, 2) the risk of developing CVD, renal disease, or stroke later in life for women with hypertensive pregnancies, and 3) the effects of a hypertensive pregnancy on the offspring.

Long term follow up of biomarkers of podocyte damage and renal function in patients with and without preeclampsia

Introduction:

preeclampsia can be associated with future renal disease.

Objectives:

To measure changes in renal function overtime in patients with preeclampsia.

Methods:

urine and serum samples from eleven patients with preeclampsia and eight patients with a normal pregnancy were obtained during pregnancy, postpartum, and 3 years after delivery. Urine podocalyxin, protein, and serum creatinine were measured.

Results:

after 3 years, there were no significant differences in urinary podocalyxin in patients with or without preeclampsia: 4.34 ng/mg [2.69, 8.99] vs. 7.66 ng/mg [2.35, 13], p = 0.77. The same applied to urinary protein excretion: 81.5 mg/g [60.6, 105.5] vs. 43.2 mg/g [20.9, 139.3] p = 0.23. Serum creatinine was 0.86 mg/dL [0.7, 0.9] vs. 0.8 mg/dL [0.68, 1] p = 0.74 in those with and without preeclampsia. In normal patients, urinary podocalyxin decreased from 54.4 ng/mg [34.2, 76.9] during pregnancy to 7.66 ng/mg [2.35, 13] three years after pregnancy, p = 0.01. Proteinuria decreased from 123.5 mg/g [65.9, 194.8] to 43.2 mg/g [20.9, 139.3], p = 0.12. In preeclampsia patients, urinary podocalyxin decreased from 97.5 ng/mg [64.9, 318.4] during pregnancy to 37.1 ng/mg within one week post-partum [21.3, 100.4] p = 0.05 and 4.34 ng/mg [2.69, 8.99] three years after, p = 0.003. Proteinuria was 757.2 mg/g [268.4, 5031.7] during pregnancy vs. 757.2 mg/g [288.2, 2917] postpartum, p = 0.09 vs. 81.5 mg/g [60.6, 105.5] three years later, p = 0.01. Two patients still had proteinuria after 3 years.

Conclusions:

in preeclampsia patients, postpartum urinary podocalyxin decreased before proteinuria. After three years, serum creatinine, urinary podocalyxin, and protein tended to normalize, although some patients still had proteinuria.

Biomarkers of glomerular dysfunction in pre-eclampsia - A systematic review

BACKGROUND

Early detection of pre-eclampsia remains one of the major focuses of antenatal obstetric care. There is often a delay in the diagnosis, mainly due to the non-specific nature of the condition. Podocytes which play a pivotal role in glomerular function become injured in pre-eclampsia leading to subsequent proteinuria. Our aim was to review available studies to determine the clinical utility of biomarkers of podocyte injury in pre-eclampsia.

METHODS

We used QUADAS (Quality Assessment of Diagnostic Accuracy Studies) criteria to perform a systematic review of the literature to determine the clinical utility of podocyte injury biomarkers in predicting pre-eclampsia.

RESULTS

This study identified five potential renal biomarkers including podocytes, nephrin, synaptopodin, podocin and podocalyxin. The pooled sensitivity of all biomarkers was 0.78 (95% CI 0.74-0.82) with a specificity of 0.82 (95% CI 0.79-0.85). The area under the Summary of Receiver Operating Characteristics Curve (SROC) was 0.926 (SE 0.30). Urinary nephrin achieved the highest diagnostic values with a sensitivity of 0.81 (95% CI 0.72-0.88) and specificity of 0.84 (95% CI 0.79-0.84).

CONCLUSION

Biomarkers of glomerular injury show promise as diagnostic aids in pre-eclampsia. A large-scale prospective cohort study is warranted before these biomarkers can be recommended for routine clinical care.

Cardiovascular Sequels During and After Preeclampsia

Preeclampsia is a pregnancy-specific disorder complicating 2%-8% of pregnancies worldwide and characterized by de novo development of hypertension and proteinuria. Current understanding of the pathophysiology of preeclampsia is limited. A main feature is disrupted spiral artery remodeling in the placenta, which restricts the blood flow to the placenta, which in turn leads to decreased uteroplacental perfusion. Impaired blood flow through the placenta might result in fetal growth restriction and secretion of several factors by the placenta-mainly pro-inflammatory cytokines and anti-angiogenic factors-which spread into the maternal circulation, leading to endothelial dysfunction, which subsequently results in disrupted maternal hemodynamics. To date, no treatment options are available apart from termination of pregnancy. Despite normalization of the maternal vascular disturbances after birth, it has become apparent that formerly preeclamptic women experience an increased risk to develop cardiovascular and kidney disease later in life. One well-accepted concept is that the development of preeclampsia is an indicator of maternal susceptibility to develop future cardiovascular conditions, although the increased risk might also be the result of organ damage caused during preeclampsia. Given the associations between preeclampsia and long-term complications, preeclampsia is acknowledged as woman-specific risk factor for cardiovascular disease. Current research focuses on finding effective screening and prevention strategies for the reduction of cardiovascular disease in women with a history of preeclampsia.

Vascular Dysfunction in Mother and Offspring During Preeclampsia: Contributions from Latin-American Countries

Pregnancy is a physiologically stressful condition that generates a series of functional adaptations by the cardiovascular system. The impact of pregnancy on this system persists from conception beyond birth. Recent evidence suggests that vascular changes associated with pregnancy complications, such as preeclampsia, affect the function of the maternal and offspring vascular systems, after delivery and into adult life. Since the vascular system contributes to systemic homeostasis, defective development or function of blood vessels predisposes both mother and infant to future risk for chronic disease. These alterations in later life range from fertility problems to alterations in the central nervous system or immune system, among others. It is important to note that rates of morbi-mortality due to pregnancy complications including preeclampsia, as well as cardiovascular diseases, have a higher incidence in Latin-American countries than in more developed countries. Nonetheless, there is a lack both in the amount and impact of research conducted in Latin America. An impact, although smaller, can be seen when research in vascular disorders related to problems during pregnancy is analyzed. Therefore, in this review, information about preeclampsia and endothelial dysfunction generated from research groups based in Latin-American countries will be highlighted. We relate the need, as present in many other countries in the world, for increased effective regional and international collaboration to generate new data specific to our region on this topic.

Podocytes from the diagnostic and therapeutic point of view

The central role of podocytes in glomerular diseases makes this cell type an interesting diagnostic tool as well as a therapeutic target. In this review, we discuss the current literature on the use of podocytes and podocyte-specific markers as non-invasive diagnostic tools in different glomerulopathies. Furthermore, we highlight the direct effects of drugs currently used to treat primary glomerular diseases and describe their direct cellular effects on podocytes. A new therapeutic potential is seen in drugs targeting the podocytic actin cytoskeleton which is essential for podocyte foot process structure and function. Incubation of cultured human podocyte cell lines with sera from patients with active glomerular diseases is currently also used to identify novel circulating factors with pathophysiological relevance for the glomerular filtration barrier. In addition, treatment of detached urinary podocytes from patients with substances that restore their cytoskeleton might serve as a novel personalized tool to estimate their potential for podocyte recovery ex vivo.

A Multicenter Cohort Study of Histologic Findings and Long-Term Outcomes of Kidney Disease in Women Who Have Been Pregnant

BACKGROUND AND OBJECTIVES

For many women pregnancy is the first contact with health services, thus providing an opportunity to identify renal disease. This study compares causes and long-term renal outcomes of biopsy-proven renal disease identified during pregnancy or within 1 year postpartum, with nonpregnant women.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Native renal biopsies (1997-2012), in women of childbearing age (16 to <50 years), from 21 hospitals were studied. The pregnancy-related diagnosis group included those women with abnormal urinalysis/raised creatinine identified during pregnancy or within 1 year postpartum. Pregnancy-related and control biopsies were matched for age and ethnicity (black versus nonblack).

RESULTS

One hundred and seventy-three pregnancy-related biopsies (19 antenatal, 154 postpregnancy) were identified and matched with 1000 controls. FSGS was more common in pregnancy-related biopsies (32.4%) than controls (9.7%) (P<0.001) but there were no differences in Columbia classification. Women with a pregnancy-related diagnosis were younger (32.1 versus 34.2 years; P=0.004) and more likely to be black (26.0% versus 13.3%; P<0.001) than controls, although there were no differences in ethnicities in women with FSGS. The pregnancy-related group (excluding antenatal biopsies) was more likely to have a decline in Chronic Kidney Disease Epidemiology Collaboration eGFR in the follow-up period than the control group (odds ratio, 1.67; 95% confidence interval, 1.03 to 2.71; P=0.04), and this decline appeared to be more rapid (-1.33 versus -0.56 ml/min per 1.73 m2 per year, respectively; P=0.045). However, there were no differences between groups in those who required RRT or who died.

CONCLUSIONS

Pregnancy is an opportunity to detect kidney disease. FSGS is more common in women who have been pregnant than in controls, and disease identified in pregnancy or within 1 year postpartum is more likely to show a subsequent decline in renal function. Further work is required to determine whether pregnancy initiates, exacerbates, or reveals renal disease.

Pregnancy as a critical window for blood pressure regulation in mother and child: programming and reprogramming

Pregnancy is a critical time for long-term blood pressure regulation in both mother and child. Pregnancies complicated by placental insufficiency, resulting in pre-eclampsia and intrauterine growth restriction, are associated with a threefold increased risk of the mother to develop hypertension later in life. In addition, these complications create an adverse intrauterine environment, which programmes the foetus and the second generation to develop hypertension in adult life. Female offspring born to a pregnancy complicated by placental insufficiency are at risk for pregnancy complications during their own pregnancies as well, resulting in a vicious circle with programmed risk for hypertension passing from generation to generation. Here, we review the epidemiology and mechanisms leading to the altered programming of blood pressure trajectories after pregnancies complicated by placental insufficiency. Although the underlying mechanisms leading to hypertension remain the subject of investigation, several abnormalities in angiotensin sensitivity, sodium handling, sympathetic activity, endothelial function and metabolic pathways are found in the mother after exposure to placental insufficiency. In the child, epigenetic modifications and disrupted organ development play a crucial role in programming of hypertension. We emphasize that pregnancy can be viewed as a window of opportunity to improve long-term cardiovascular health of both mother and child, and outline potential gains expected of improved preconceptional, perinatal and post-natal care to reduce the development of hypertension and the burden of cardiovascular disease later in life. Perinatal therapies aimed at reprogramming hypertension are a promising strategy to break the vicious circle of intergenerational programming of hypertension.

Urinary Podocyte Loss Is Increased in Patients with Fabry Disease and Correlates with Clinical Severity of Fabry Nephropathy

Chronic kidney disease is a major complication of Fabry disease. Podocytes accumulate globotriaosylceramide inclusions more than other kidney cell types in Fabry patients. Podocyte injury occurs early in age, and is progressive. Since injured podocytes detach into the urine (podocyturia), we hypothesized that podocyturia would increase in Fabry patients and correlate with clinical severity of Fabry nephropathy. Urine specimens from 39 Fabry patients and 24 healthy subjects were evaluated for podocyturia. Most of the Fabry patients and many healthy subjects had podocyturia. The number of podocytes per gram of urine creatinine (UPodo/g Cr) was 3.6 fold greater in Fabry patients (3,741 ± 2796; p = 0.001) than healthy subjects (1,040 ± 972). Fabry patients with normoalbuminuria and normoproteinuria had over 2-fold greater UPodo/g Cr than healthy subjects (p = 0.048). UPodo/gCr was inversely related to eGFR in male patients (r = -0.69, p = 0.003). UPodo/gCr was directly related to urine protein creatinine ratio (r = 0.33; p = 0.04) in all Fabry patients. These studies confirm increased podocyturia in Fabry disease, even when proteinuria and albuminuria are absent. Podocyturia correlates with clinical severity of Fabry nephropathy, and potentially may be of prognostic value.

Preeclampsia and ESRD: The Role of Shared Risk Factors

BACKGROUND

Several registry-based studies, using diagnostic codes, have suggested that preeclampsia is a risk factor for end-stage renal disease (ESRD). However, because the 2 diseases share risk factors, the true nature of their association remains uncertain. Our goals were to conduct a population-based study to determine the magnitude of the association between preeclampsia and ESRD and evaluate the role of shared risk factors.

STUDY DESIGN

Population-based nested case-control study.

SETTING & PARTICIPANTS

The US Renal Data System was used to identify women with ESRD from a cohort of 34,581 women who gave birth in 1976 to 2010 in Olmsted County, MN. 44 cases of ESRD were identified and each one was matched to 2 controls based on year of birth (±1 year), age at first pregnancy (±2 years), and parity (±1 or ≥4).

PREDICTOR

Preeclamptic pregnancy, confirmed by medical record review.

OUTCOME

ESRD.

MEASUREMENTS

Prepregnancy serum creatinine and urine protein measurements were recorded. Comorbid conditions existing prior to pregnancy were abstracted from medical records and included kidney disease, obesity, diabetes, and hypertension.

RESULTS

There was evidence of kidney disease prior to the first pregnancy in 9 of 44 (21%) cases and 1 of 88 (<1%) controls. Per chart review, 8 of 44 (18%) cases versus 4 of 88 (5%) controls had preeclamptic pregnancies (unadjusted OR, 4.0; 95% CI, 1.21-13.28). Results were similar after independent adjustment for race, education, diabetes, and hypertension prior to pregnancy. However, the association was attenuated and no longer significant after adjustment for obesity (OR, 3.25; 95% CI, 0.93-11.37).

LIMITATIONS

The limited number of ESRD cases and missing data for prepregnancy kidney function.

CONCLUSIONS

Our findings confirm that there is a sizable association between preeclampsia and ESRD; however, obesity is a previously unexplored confounder. Pre-existing kidney disease was common, but not consistently coded or diagnosed.

Pregnancy in Women With CKD: A Success Story

In women with chronic kidney disease (CKD), pregnancy outcomes have improved over the last 50 years, particularly in the developed world. Maternal mortality is now extremely low, fetal survival has markedly increased (even in women with CKD stages 4-5), and it is now the exception for women with CKD to be advised against embarking on a pregnancy. However, pregnancies are rarely free from complications, and there are unanswered questions about the longer term effects on maternal and infant health. The developments have led to a more optimistic attitude to pregnancy in women with CKD not requiring renal replacement treatment. The remaining problems are described in this World Kidney Forum.

A best practice position statement on pregnancy in chronic kidney disease: the Italian Study Group on Kidney and Pregnancy

Pregnancy is increasingly undertaken in patients with chronic kidney disease (CKD) and, conversely, CKD is increasingly diagnosed in pregnancy: up to 3 % of pregnancies are estimated to be complicated by CKD. The heterogeneity of CKD (accounting for stage, hypertension and proteinuria) and the rarity of several kidney diseases make risk assessment difficult and therapeutic strategies are often based upon scattered experiences and small series. In this setting, the aim of this position statement of the Kidney and Pregnancy Study Group of the Italian Society of Nephrology is to review the literature, and discuss the experience in the clinical management of CKD in pregnancy. CKD is associated with an increased risk for adverse pregnancy-related outcomes since its early stage, also in the absence of hypertension and proteinuria, thus supporting the need for a multidisciplinary follow-up in all CKD patients. CKD stage, hypertension and proteinuria are interrelated, but they are also independent risk factors for adverse pregnancy-related outcomes. Among the different kidney diseases, patients with glomerulonephritis and immunologic diseases are at higher risk of developing or increasing proteinuria and hypertension, a picture often difficult to differentiate from preeclampsia. The risk is higher in active immunologic diseases, and in those cases that are detected or flare up during pregnancy. Referral to tertiary care centres for multidisciplinary follow-up and tailored approaches are warranted. The risk of maternal death is, almost exclusively, reported in systemic lupus erythematosus and vasculitis, which share with diabetic nephropathy an increased risk for perinatal death of the babies. Conversely, patients with kidney malformation, autosomal-dominant polycystic kidney disease, stone disease, and previous upper urinary tract infections are at higher risk for urinary tract infections, in turn associated with prematurity. No risk for malformations other than those related to familiar urinary tract malformations is reported in CKD patients, with the possible exception of diabetic nephropathy. Risks of worsening of the renal function are differently reported, but are higher in advanced CKD. Strict follow-up is needed, also to identify the best balance between maternal and foetal risks. The need for further multicentre studies is underlined.

Quantitative podocyte parameters predict human native kidney and allograft half-lives

BACKGROUND

Kidney function decreases with age. A potential mechanistic explanation for kidney and allograft half-life has evolved through the realization that linear reduction in glomerular podocyte density could drive progressive glomerulosclerosis to impact both native kidney and allograft half-lives.

METHODS

Predictions from podometrics (quantitation of podocyte parameters) were tested using independent pathologic, functional, and outcome data for native kidneys and allografts derived from published reports and large registries.

RESULTS

With age, native kidneys exponentially develop glomerulosclerosis, reduced renal function, and end-stage kidney disease, projecting a finite average kidney life span. The slope of allograft failure rate versus age parallels that of reduction in podocyte density versus age. Quantitative modeling projects allograft half-life at any donor age, and rate of podocyte detachment parallels the observed allograft loss rate.

CONCLUSION

Native kidneys are designed to have a limited average life span of about 100-140 years. Allografts undergo an accelerated aging-like process that accounts for their unexpectedly short half-life (about 15 years), the observation that older donor age is associated with shorter allograft half-life, and the fact that long-term allograft survival has not substantially improved. Podometrics provides potential readouts for these processes, thereby offering new approaches for monitoring and intervention.

FUNDING

National Institutes of Health.

Vascular Endothelial Growth Factor and Podocyte Protection in Chronic Hypoxia: Effects of Endothelin-A Receptor Antagonism

BACKGROUND

Podocytes are major components of the filtration barrier and a renal source of vascular endothelial growth factor (VEGF). Chronic renovascular disease (RVD) progressively degrades the renal function, accompanied by podocyte damage and a progressive reduction in VEGF. We showed that the endothelin (ET) pathway contributes to this pathological process and ET-A (but not ET-B) receptor antagonism protects the kidney in RVD. We hypothesize that ET-A-induced renoprotection is largely driven by the protection of podocyte integrity and function.

METHODS

To mimic the renal environment of chronic RVD, human podocytes were incubated under chronic hypoxia for 96 h and divided in untreated or treated with an ET-A or ET-B receptor antagonist. Cells were quantified after 96 h. Cell homogenates and media were obtained after 1, 24 and 96 h to quantify production of VEGF, anti-VEGF soluble receptor s-Flt1, and the expression of apoptotic mediators. A separate set of similar experiments was performed after addition of a VEGF-neutralizing antibody (VEGF-NA).

RESULTS

Hypoxia decreased podocyte number, which was exacerbated by ET-B but improved after ET-A antagonism. Production of VEGF was preserved by ET-A antagonism, whereas s-Flt1 increased in hypoxic cells after ET-B antagonism only, accompanied by a greater expression of pro-apoptotic mediators. On the other hand, treatment with VEGF-NA diminished ET-A-induced protection of podocytes.

CONCLUSION

ET-A antagonism preserves podocyte viability and integrity under chronic hypoxia, whereas ET-B antagonism exacerbates podocyte dysfunction and death. Enhanced bioavailability of VEGF after ET-A antagonism could be a pivotal mechanism of podocyte protection that significantly contributes to ET-A receptor blockade-induced renal recovery in chronic RVD.

Is there a role for urinary podocyte excretion assessment in lupus nephritis?

OBJECTIVE

To establish the occurrence and intensity of podocyturia and its relation to grade of disease activity, as defined by clinical and laboratory criteria.

METHODS

Prospective, cross-sectional study involving 50 patients with lupus nephritis and 29 controls, which had podocyturia levels determined from random urine samples using an immunofluorescence technique. Disease activity was graded by BILAG (renal criteria) and an additional system used in the service (S2).

RESULTS

Fifty patients with lupus nephritis (WHO classes III, IV and V), with a median age of 37 years, were evaluated. Of these, 86.5% were female, and 52% were BILAG A. Podocyturia quantification in the lupus nephritis and control groups differed significantly (p = 0.009). This score was higher in relation to classes III, IV and V. The correlation with C3 consumption was stronger (p = 0.011) than with C4. The highest levels were found in the most active groups (A and B of BILAG and S2). Lower podocyturia correlated with a lower dose of prednisone. There was no association with the intensity of proteinuria, hematuria or pyuria, serum creatinine levels, among others.

CONCLUSIONS

Podocyturia assessment, which was performed by immunofluorescence in this study, can be used as an indicator of disease activity with the advantage of being a urinary biomarker. The levels proved to be higher in patients with lupus nephritis than in the controls and were particularly higher in class IV.

Is It Possible to Differentiate Chronic Kidney Disease and Preeclampsia by means of New and Old Biomarkers? A Prospective Study

Objective. Chronic kidney disease (CKD) and preeclampsia (PE) may both present with hypertension and proteinuria in pregnancy. Our objective is to test the possibility of distinguishing CKD from PE by means of uteroplacental flows and maternal circulating sFlt-1/PlGF ratio. Design. Prospective analysis. Population. Seventy-six patients (35 CKD, 24 PE, and 17 other hypertensive disorders), with at least one sFlt-1/PlGF and Doppler evaluation after the 20th gestational week. Methods. Maternal sFlt-1-PlGF were determined by immunoassays. Abnormal uterine artery Doppler was defined as resistance index ≥ 0.58. Umbilical Doppler was defined with gestational-age-adjusted Pulsatility Index. Clinical diagnosis was considered as reference. Performance of Doppler study was assessed by sensitivity analysis; sFlt-1/PlGF cut-off values were determined by ROC curves. Results. The lowest sFlt-1/PlGF ratio (8.29) was detected in CKD, the highest in PE (317.32) (P < 0.001). Uteroplacental flows were mostly preserved in CKD patients in contrast to PE (P < 0.001). ROC analysis suggested two cut-points: sFlt-1/PlGF ≥ 32.81 (sensitivity 82.93%; specificity 91.43%) and sFlt-1/PlGF ≥ 78.75 (sensitivity 62.89%, specificity 97.14%). Specificity reached 100% at sFlt-1/PlGF ≥ 142.21 (sensitivity: 48.8%). Early-preterm delivery was associated with higher sFlt-1/PlGF ratio and abnormal uteroplacental flows relative to late-preterm and term deliveries. Conclusions. sFlt-1/PlGF ratio and uteroplacental flows significantly correlated with PE or CKD and preterm delivery.