Increased urinary levels of podocyte glycoproteins, matrix metallopeptidases, inflammatory cytokines, and kidney injury biomarkers in women with preeclampsia

Urinary biomarkers in neonates born to mothers with preeclampsia: A case-control study

BACKGROUND

Effects of preeclampsia (PE) on fetal renal development are unknown. We hypothesized that the circulating factors causing endothelial dysfunction and impaired renal function in mothers with PE adversely affect fetal kidneys.

OBJECTIVE

To compare urinary biomarkers in infants born to mothers with and without PE.

METHODS

Sixty-eight mothers and their newborns with gestational age ≥ 32 weeks were enrolled. We collected bag urine samples from infants during the first 48 h of life. Urine samples were centrifuged at 1500 rpm for 10 min. Supernatant after excluding the bottom 1 mL of urine was stored at -70 °C until assayed. Urinary creatinine, protein, cystatin C, nephrin, kidney injury molecule - 1, and klotho were measured.

RESULTS

Sixteen mothers in the PE group had severe features of PE. The PE group infants had lower body length compared to the control group (46.4 ± 3.4 vs 48.6 ± 3.4 cm; p = 0.007). Urine protein and creatinine were significantly higher in the PE group infants [protein 37.1 (14.4, 53.5) vs 20.3 (7.5, 30.0) mg/dl, p = 0.04; creatinine 63.4 (25.2, 96.6) vs 24.8 (19.8, 44.2) mg/dl, p = 0.008]. There were no statistically significant differences in the urinary concentrations of the remaining four biomarkers. The urinary protein, creatinine and nephrin concentrations had significant negative correlation with gestational age (p values 0.07, 0.0003 and 0.0008 respectively).

CONCLUSIONS

The findings of higher urinary protein and the observed trends in the levels of urinary nephrin and klotho are suggestive of glomerular immaturity and/or impaired function in infants born to mothers with PE.

Is renal dysfunction amplified in an arginine vasopressin induced rat model of preeclampsia?

Renal dysfunction is important in preeclampsia (PE) pathophysiology and has not been fully explored in the arginine vasopressin (AVP) rat model of PE. This study aimed to determine kidney toxicity associated with this model. Female Sprague Dawley rats (n = 24) were subcutaneously infused with AVP or saline for 18 days. Urine samples (GD8, 14 and 18) were used to determine the levels of albumin, VEGF-A, clusterin, NGAL/Lipocalin-2, KIM-1, cystatin C, TIMP-1, β2M and OPN via Multiplex ELISAs. Albumin, and NGAL/lipocalin-2 were significantly elevated in the PAVP vs PS group on GD14 and GD18 (p < 0.001) respectively. VEGF-A significantly decreased in the pregnant vs non-pregnant groups on GD14 and 18 (p < 0.001). Clusterin (p < 0.001) and OPN (p < 0.05) were significantly higher in the PAVP vs PS group on GD18. Cystatin C and KIM-1 are significantly upregulated in the PAVP vs PS groups throughout gestation (p < 0.05). β2M is significantly elevated in the PAVP vs PS group on GD14 and 18 (p < 0.05). AVP elevated the urinary levels of the kidney injury biomarkers and replicated the renal dysfunction associated with PE development. Our findings confirm the potential applications of this model in studying the mechanisms underlying renal damage in PE.

Machine learning: a new era for cardiovascular pregnancy physiology and cardio-obstetrics research

The maternal cardiovascular system undergoes functional and structural adaptations during pregnancy and postpartum to support increased metabolic demands of offspring and placental growth, labor, and delivery, as well as recovery from childbirth. Thus, pregnancy imposes physiological stress upon the maternal cardiovascular system, and in the absence of an appropriate response it imparts potential risks for cardiovascular complications and adverse outcomes. The proportion of pregnancy-related maternal deaths from cardiovascular events has been steadily increasing, contributing to high rates of maternal mortality. Despite advances in cardiovascular physiology research, there is still no comprehensive understanding of maternal cardiovascular adaptations in healthy pregnancies. Furthermore, current approaches for the prognosis of cardiovascular complications during pregnancy are limited. Machine learning (ML) offers new and effective tools for investigating mechanisms involved in pregnancy-related cardiovascular complications as well as the development of potential therapies. The main goal of this review is to summarize existing research that uses ML to understand mechanisms of cardiovascular physiology during pregnancy and develop prediction models for clinical application in pregnant patients. We also provide an overview of ML platforms that can be used to comprehensively understand cardiovascular adaptations to pregnancy and discuss the interpretability of ML outcomes, the consequences of model bias, and the importance of ethical consideration in ML use.

Urinary phenol and paraben concentrations in association with markers of inflammation during pregnancy in Puerto Rico

Exposure to phenols and parabens may contribute to increased maternal inflammation and adverse birth outcomes, but these effects are not well-studied in humans. This study aimed to investigate relationships between concentrations of 8 phenols and 4 parabens with 6 inflammatory biomarkers (C-reactive protein (CRP); matrix metalloproteinases (MMP) 1, 2, and 9; intercellular adhesion molecule-1 (ICAM-1); and vascular cell adhesion molecule-1 (VCAM-1)) measured at two time points in pregnancy in the PROTECT birth cohort in Puerto Rico. Linear mixed models were used, adjusting for covariates of interest. Results are expressed as the percent change in outcome per interquartile range (IQR) increase in exposure. Particularly among phenols, numerous significant negative associations were found, for example, between benzophenone-3 and CRP (-11.21 %, 95 % CI: -17.82, -4.07) and triclocarban and MMP2 (-9.87 %, 95 % CI: -14.05, -5.5). However, significant positive associations were also detected, for instance, between bisphenol-A (BPA) and CRP (9.77 %, 95 % CI: 0.67, 19.68) and methyl-paraben and MMP1 (10.78 %, 95 % CI: 2.17, 20.11). Significant interactions with female fetal sex and the later study visit (at 24-28 weeks gestation) showed more positive associations compared to male fetal sex and the earlier study visit (16-20 weeks gestation). Our results suggest that phenols and parabens may disrupt inflammatory processes pertaining to uterine remodeling and endothelial function, with important implications for pregnancy outcomes. More research is needed to further understand maternal inflammatory status in an effort to improve reproductive and developmental outcomes.

Mouse models of preeclampsia with preexisting comorbidities

Preeclampsia is a pregnancy-specific condition and a leading cause of maternal and fetal morbidity and mortality. It is thought to occur due to abnormal placental development or dysfunction, because the only known cure is delivery of the placenta. Several clinical risk factors are associated with an increased incidence of preeclampsia including chronic hypertension, diabetes, autoimmune conditions, kidney disease, and obesity. How these comorbidities intersect with preeclamptic etiology, however, is not well understood. This may be due to the limited number of animal models as well as the paucity of studies investigating the impact of these comorbidities. This review examines the current mouse models of chronic hypertension, pregestational diabetes, and obesity that subsequently develop preeclampsia-like symptoms and discusses how closely these models recapitulate the human condition. Finally, we propose an avenue to expand the development of mouse models of preeclampsia superimposed on chronic comorbidities to provide a strong foundation needed for preclinical testing.

Evidence of kidney injury in preeclampsia: Increased maternal and urinary levels of NGAL and KIM-1 and their enhanced expression in proximal tubule epithelial cells

Background and objective

Proteinuria and glomerular endotheliosis are characteristics of glomerular injury in preeclampsia, a hypertensive disorder in human pregnancy. Neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) are biomarkers of acute/chronic renal tubule injury. To determine if tubule injury occurs in preeclampsia, we determined maternal plasma and urine NGAL and KIM-1 levels and evaluated NGAL and KIM-1 expression in kidney biopsy specimens from women with preeclampsia.

Methods

Prenatal and postpartum maternal blood and urinary samples were collected from three groups of pregnant women: normal pregnancy (n = 100), preeclampsia (n = 83), and pregnancy complicated with chronic hypertension (n = 20). Plasma and urine levels of NGAL and KIM-1 were measured by ELISA. Kidney biopsy tissue sections from patients with preeclampsia (n = 5) were obtained from Pathology Archives and processed to determine NGAL and KIM-1 expression by immunostaining and high kidney solution images were assessed by electron microscopy (EM).

Results

Prenatal plasma and urine levels of NGAL and KIM-1 were significantly higher in preeclamptic than in normal controls, p &lt; 0.01. In normal pregnancy, both plasma and urine levels of NGAL and KIM-1 at 24–48 h after delivery and 6–8 weeks postpartum were relatively comparable to that of antenatal levels. In preeclampsia, urine, but not plasma, NGAL levels were reduced at 6–8 weeks postpartum compared to the antenatal levels, p &lt; 0.05. Although maternal and urine KIM-1 levels were reduced at 6–8 weeks postpartum compared to the antenatal levels in preeclampsia, the levels were still higher than those in normal pregnancy. Positive expression of NGAL and KIM-1 was detected in proximal tubule epithelial cells in kidney tissue specimens from preeclampsia but not in non-pregnancy controls. EM examination showed glomerular and tubular injury in preeclampsia.

Conclusion

Our findings of increased maternal levels and urine secretion of NGAL and KIM-1, along with the upregulation of NGAL and KIM-1 expression in tubular epithelial cells in preeclampsia, provide plausible evidence that tubular injury exists in preeclampsia. The higher postpartum NGAL and KIM-1 levels in preeclamptic pregnancies indicate that tubular injury would not resolve within 2–3 months after delivery and suggest that proper follow-up and management of kidney function in women with preeclampsia would be necessary to reduce chronic kidney diseases in those women later in life.

Pregnancy History and Kidney Disease Progression Among Women Enrolled in Cure Glomerulonephropathy

Introduction

Preeclampsia increases the risk for future chronic kidney disease (CKD). Among those diagnosed with CKD, it is unclear whether a prior history of preeclampsia, or other complications in pregnancy, negatively impact kidney disease progression. In this longitudinal analysis, we assessed kidney disease progression among women with glomerular disease with and without a history of a complicated pregnancy.

Methods

Adult women enrolled in the Cure Glomerulonephropathy study (CureGN) were classified based on a history of a complicated pregnancy (defined by presence of worsening kidney function, proteinuria, or blood pressure; or a diagnosis of preeclampsia, eclampsia, or hemolysis, elevated liver enzymes, and low platelets [HELLP] syndrome), pregnancy without these complications, or no pregnancy history at CureGN enrollment. Linear mixed models were used to assess estimated glomerular filtration rate (eGFR) trajectories and urine protein-to-creatinine ratios (UPCRs) from enrollment.

Results

Over a median follow-up period of 36 months, the adjusted decline in eGFR was greater in women with a history of a complicated pregnancy compared to those with uncomplicated or no pregnancies (-1.96 [-2.67, -1.26] vs. -0.80 [-1.19, -0.42] and -0.64 [-1.17, -0.11] ml/min per 1.73 m2 per year, P = 0.007). Proteinuria did not differ significantly over time. Among those with a complicated pregnancy history, eGFR slope did not differ by timing of first complicated pregnancy relative to glomerular disease diagnosis.

Conclusions

A history of complicated pregnancy was associated with greater eGFR decline in the years following glomerulonephropathy (GN) diagnosis. A detailed obstetric history may inform counseling regarding disease progression in women with glomerular disease. Continued research is necessary to better understand pathophysiologic mechanisms by which complicated pregnancies contribute to glomerular disease progression.

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.

Nephrinuria and podocytopathies

The discovery of nephrin in 1998 has launched a new era in glomerular diseases research, emphasizing its crucial role in the structure and function of the glomerular filtration barrier. In the past 20 years, substantial advances have been made in understanding podocyte structure and function as well as the discovery of several podocyte-related proteins including nephrin. The glomerular filtration barrier is comprised of podocytes, the glomerular basement membrane and endothelial cells. Podocytes, with their specialized slit diaphragm, form the essential backbone of the glomerular filtration barrier. Nephrin is a crucial structural and functional feature of the slit diaphragm that prevents plasma protein, blood cell and macromolecule leakage into the urine. Podocyte damage results in nephrin release. Podocytopathies are kidney diseases in which podocyte damage drives proteinuria, i.e., nephrotic syndrome. Many kidney diseases involve podocytopathy including congenital nephrotic syndrome of Finnish type, diffuse mesangial sclerosis, minimal change disease, focal segmental glomerulosclerosis, collapsing glomerulonephropathy, diabetic nephropathy, lupus nephropathy, hypertensive nephropathy and preeclampsia. Recently, urinary nephrin measurement has become important in the early detection of podocytopathies. In this chapter, we elaborate the main structural and functional features of nephrin as a podocyte-specific protein, pathomechanisms of podocytopathies which result in nephrinuria, highlight the most commonly used methods for detecting urinary nephrin and investigate the diagnostic, prognostic and potential therapeutic relevance of urinary nephrin in primary and secondary proteinuric kidney diseases.

Empagliflozin Ameliorates Preeclampsia and Reduces Postpartum Susceptibility to Adriamycin in a Mouse Model Induced by Angiotensin Receptor Agonistic Autoantibodies

Preeclampsia (PE) is the leading cause of maternal and perinatal morbidity and mortality and also is a risk factor for cardiovascular and kidney disease later in life. PE is associated with oversecretion of autoantibodies against angiotensin II type 1 receptor (AT1-AA) by the placenta into the maternal circulation. Here, we sought to determine the therapeutic value of the sodium-glucose co-transporter 2 (SGLT2) inhibitor empagliflozin (EMPA) in mice with AT1-AA-induced preeclampsia. Pregnant mice were injected with AT1-AA at gestation day (GD) 13 and treated daily with EMPA until GD 19, at which point some of the maternal mice were sacrificed and assessed. The other maternal mice were labored on time and challenged with adriamycin (ADR) at 12 weeks postpartum; their offspring were assessed for fetal outcomes. We showed that EMPA treatment significantly relieved high systolic blood pressure and proteinuria and ameliorated kidney injury in PE mice without affecting fetal outcomes. EMPA also ameliorated podocyte injury and oxidative stress, reduced the expression of SGLT2 and activated the AMPK/SIRT1 signaling pathway in vivo and in vitro. Remarkably, EMPA treatment during pregnancy reduced ADR-induced kidney and podocyte injury postpartum. These findings suggest that EMPA could be a potential pharmacological agent for PE.

Serum Netrin-1 and Urinary KIM-1 levels as potential biomarkers for the diagnosis of early preeclampsia

The aim of this study was to evaluate whether the Serum Netrin-1 and Urinary KIM-1 (Kidney Injury Molecule-1) levels are associated with the detection of preeclampsia. A total of 90 patients, including 36 normal pregnant women, 29 patients with nonsevere preeclampsia and 25 patients with severe preeclampsia, were included in this study. Maternal serum Netrin-1 and Urinary KIM-1 levels were measured by using an enzyme-linked immunosorbent assay (ELISA). The results showed that the Levels of Netrin-1 and KIM-1 were statistically higher in women with preeclampsia as compared with normal pregnant women. Furthermore, the Netrin-1 level in women with severe preeclampsia was significantly higher than nonsevere preeclamptic women. inconclusion the current study showed that Maternal serum level of Netrin-1 and Urinary level of KIM-1 can be used as early biomarkers for the detection of preeclampsia.IMPACT STATEMENTWhat is already known on this subject? Preeclampsia is a disorder of widespread vascular endothelial malfunction and vasospasm that occurs after 20 weeks' gestation. Netrin-1 was found to promote angiogenesis. Alteration of placental angiogenesis in early pregnancy is a well-known reason for placental dysfunction such as preeclampsia. Kidney injury with proteinuria is a characteristic feature of preeclampsia. Urine KIM-1 is the most potential biomarker for renal injury in preeclampsia. Due to these facts, we aimed to investigate the role of maternal serum Netrin-1 and Urine KIM-1 levels in preeclampsia presence and severity.What the results of this study add? A significant relationship between Netrin-1 and KIM-1 levels with preeclampsia.What the implications are of these findings for clinical practice and/or further research? Based on these findings, we concluded that increased levels of Netrin-1 and KIM-1 are associated with severe preeclampsia.

New views on endothelial dysfunction in gestational hypertension and potential therapy targets

The placenta has vital roles in metabolite exchange, fetal growth, and pre-eclampsia (PE). In this review, we discuss the pathogenesis of hypertension in pregnancy, focusing on four major theories to explain PE, discussing endothelial roles in those theories. We focus in particular on the roles of nitric oxide (NO) and prostacyclin (PGI₂) in placental endothelium, and propose new hypotheses for the influence and mechanisms of endothelial NO and PGI₂ signaling pathways in PE.

Effect of preeclampsia and its severity on maternal serum NGAL and KIM-1 levels during pregnancy and the post-pregnancy period

OBJECTIVE

The purpose of this trial was to appraise the effects of preeclampsia and its intensity on maternal serum neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) levels during pregnancy and the post-pregnancy period.

STUDY DESIGN

Firstly pregnant participants (n = 156) were separated into three groups, as control, mild, and severe preeclampsia. Secondly women in post-pregnancy period (n = 368) were separated into three groups according to history of pregnancy, as healthy control, mild, and severe preeclampsia. These women were identified through the hospital data system and contacted by telephone to participate in the study.

RESULTS

Our study comprised 147 patients, 77 of whom were pregnant and 70 of whom were in their post-pregnancy period after the exclusion criteria had been applied. In terms of maternal serum NGAL levels, there is a significant increase in the severe preeclampsia group compared with that in the mild preeclampsia and normal pregnancy groups (p < 0.001). During the post-pregnancy period, the maternal serum NGAL levels were found significantly higher in the severe preeclampsia group than in the mild preeclampsia group and non-hypertension control group (p < 0.001). Maternal serum KIM-1 levels were found as significantly higher in the severe and mild preeclampsia groups than in the non-hypertension pregnancy group (p = 0.004). During the post-pregnancy period, maternal serum KIM-1 levels were found as similar among all post pregnant groups (p = 0.792).

CONCLUSIONS

Our results indicated that as the severity of preeclampsia increases, kidney damage as assessed using NGAL levels continues for a long period of time, even during the post-pregnancy period.

A novel urinary biomarker protein panel to identify children with ureteropelvic junction obstruction - A pilot study

INTRODUCTION AND OBJECTIVE

Reliable urinary biomarker proteins would be invaluable in identifying children with ureteropelvic junction obstruction (UPJO) as the existing biomarker proteins are inconsistent in their predictive ability. Therefore, the aim of this study was to identify consistent and reliable urinary biomarker proteins in children with UPJO.

METHODS

To identify candidate biomarker proteins, total protein from age-restricted (<2 years) and sex-matched (males) control (n = 22) and UPJO (n = 21) urine samples was analyzed by mass spectrometry. Proteins that were preferentially identified in UPJO samples were selected (2-step process) and ranked according to their diagnostic odds ratio value. The top ten proteins with highest odds ratio values were selected and tested individually by ELISA. The total amount of each protein was normalized to urine creatinine and the median with interquartile ranges for control and UPJO samples was determined. Additionally, fold change (UPJO/Control) of medians of the final panel of 5 proteins was also determined. Finally, we calculated the average + 3(SD) and average + 4(SD) values of each of the 5 proteins in the control samples and used it as an arbitrary cutoff to classify individual control and UPJO samples.

RESULTS

In the first step of our selection process, we identified 171 proteins in UPJO samples that were not detected in the majority of the control samples (16/22 samples, or 72.7%). Of the 171 proteins, only 50 proteins were detected in at least 11/21 (52.4%) of the UPJO samples and hence were selected in the second step. Subsequently, these 50 proteins were ranked according to the odds ratio value and the top 10 ranked proteins were validated by ELISA. Five of the 10 proteins - prostaglandin-reductase-1, ficolin-2, nicotinate-nucleotide pyrophosphorylase [carboxylating], immunoglobulin superfamily-containing leucine-rich-repeat-protein and vascular cell adhesion molecule-1 were present at higher levels in the UPJO samples (fold-change of the median protein concentrations ranging from 2.9 to 9.4) and emerged as a panel of biomarkers to identify obstructive uropathy. Finally, the order of prevalence of the 5 proteins in UPJO samples is PTGR1>FCN2>QPRT>ISLR>VCAM1.

CONCLUSION

In summary, this unique screening strategy led to the identification of previously unknown biomarker proteins that when screened collectively, may reliably distinguish between obstructed vs. non-obstructed infants and may prove useful in identifying informative biomarker panels for biological samples from many diseases.

Podocytes-The Most Vulnerable Renal Cells in Preeclampsia

Preeclampsia (PE) is a disorder that affects 3–5% of normal pregnancies. It was believed for a long time that the kidney, similarly to all vessels in the whole system, only sustained endothelial damage. The current knowledge gives rise to a presumption that the main role in the development of proteinuria is played by damage to the podocytes and their slit diaphragm. The podocyte damage mechanism in preeclampsia is connected to free VEGF and nitric oxide (NO) deficiency, and an increased concentration of endothelin-1 and oxidative stress. From national cohort studies, we know that women who had preeclampsia in at least one pregnancy carried five times the risk of developing end-stage renal disease (ESRD) when compared to women with physiological pregnancies. The focal segmental glomerulosclerosis (FSGS) is the dominant histopathological lesion in women with a history of PE. The kidney’s podocytes are not subject to replacement or proliferation. Podocyte depletion exceeding 20% resulted in FSGS, which is a reason for the later development of ESRD. In this review, we present the mechanism of kidney (especially podocytes) injury in preeclampsia. We try to explain how this damage affects further changes in the morphology and function of the kidneys after pregnancy.

Preeclampsia and Glomerulonephritis: A Bidirectional Association

PURPOSE OF REVIEW

We focus on the current understanding of preeclampsia (PE) in order to examine how it mediates glomerular injury and affects the course of glomerulonephritis (GNs). In addition, this review discusses the role of GNs on the development of PE.

RECENT FINDINGS

In PE, the dysfunctional utero-placental perfusion causes the release into the mother's circulation of anti-angiogenic substances, leading to systemic endotheliosis. In preeclamptic patients, the imbalance between pro- and anti-angiogenic factors is responsible for the kidney injury, and PE may reveal a silent pre-existent GN or may induce the development of the disease. Moreover, in women with chronic kidney disease (CKD), it could accelerate the disease progression. In any case, GNs compromise renal function, making the kidney less responsive to physiological changes that occur during pregnancy and, at the same time, cause maternal vascular inflammation, representing a risk factor for PE development. Although a bidirectional correlation between GNs and PE has been demonstrated, the data are limited, and further large studies are warranted. Close collaboration between a multidisciplinary team of obstetricians and nephrologists is essential to establish the correct diagnosis and safely manage these vulnerable women and their fetuses.

Loss of slit protein nephrin is associated with reduced antioxidant superoxide dismutase expression in podocytes shed from women with preeclampsia

Recent findings of podocyte shedding/podocyturia highlight the central significance of podocyte injury in preeclampsia, a hypertensive disorder unique to human pregnancy. To test the hypothesis that oxidative stress contributes to kidney podocyte injury in preeclampsia, we specifically examined expression and distribution of antioxidant CuZn‐SOD with nephrin and podoplanin in shed podocytes from women with preeclampsia. Human podocyte AB 8/13 cells served as control. We found that CuZn‐SOD was localized at the front/outreach region of nephrin at the cell periphery (foot process areas) in control podocytes and expression of CuZn‐SOD, nephrin, and podoplanin were all dislocated or lost in shed podocytes from preeclamptic patients. We further tested oxidative stress‐induced nephrin shedding in podocytes, in which AB 8/13 podocytes were cultured under lowered oxygen condition (2%O₂) or treated with hypoxic mimicking agent cobalt chloride. Our results showed that reduced nephrin and podoplanin expression were associated with downregulation of CuZn‐SOD expression in podocytes when cells were cultured under lowered oxygen or hypoxic conditions. Nephrin shed in urinary specimen from preeclamptic women was also determined by immunoprecipitation/immunoblotting. The molecular sizes of nephrin that corresponded to that were lost when cells were cultured under hypoxic conditions. We concluded that increased oxidative stress plays a significant role in inducing podocyte protein shedding in preeclampsia.

Hypertension, augmented activity of matrix metalloproteinases-2 and -9 and angiogenic imbalance in hypertensive pregnancy are attenuated by doxycycline

Preeclampsia is manifested as maternal hypertension and fetal growth restriction. Matrix metalloproteinases (MMPs) are involved in hypertension and doxycycline reduces blood pressure by inhibition of MMPs. Moreover, excessive levels of MMPs and reduced nitric oxide (NO) bioavailability have been related to preeclampsia. We investigated the involvement of MMPs in hypertension in pregnancy induced by Nω-Nitro-L-arginine methyl ester (L-NAME) in rats. To this end, zimography was performed to evaluate the activity of MMPs -2 and -9 in placenta, uterus and thoracic aorta, and systolic blood pressure, feto-placental development and metabolites of NO were evaluated. Also, plasma antioxidant capacity, plasma levels of soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PLGF) were examined. Doxycycline prevented hypertensive pregnancy and significant reductions in number of pups induced by L-NAME. Low NO bioavailability was found in hypertensive pregnant rats treated (or not) with doxycycline. Increased activity of placental MMP-2 and MMP-9 and uterine MMP-2 were attenuated by doxycycline. MMP-2 activity of thoracic aorta showed no change after hypertension. Increases in PLGF with concomitant decreases in sFlt-1 levels were found with doxycycline treatment. Also, plasma antioxidant capacity was improved with doxycycline. Also, elevations of plasma antioxidant capacity were observed in hypertensive rats treated with doxycycline. Therefore, we suggest that L-NAME reduced NO and this triggered the increases in MMP-2 and -9 activities during hypertensive pregnancy. Importantly, increases in MMPs activation and angiogenic imbalance were attenuated by doxycycline and these effects were associated with decreases in systolic blood pressure.

Proteinuric Kidney Diseases: A Podocyte's Slit Diaphragm and Cytoskeleton Approach

Proteinuric kidney diseases are a group of disorders with diverse pathological mechanisms associated with significant losses of protein in the urine. The glomerular filtration barrier (GFB), comprised of the three important layers, the fenestrated glomerular endothelium, the glomerular basement membrane (GBM), and the podocyte, dictates that disruption of any one of these structures should lead to proteinuric disease. Podocytes, in particular, have long been considered as the final gatekeeper of the GFB. This specialized visceral epithelial cell contains a complex framework of cytoskeletons forming foot processes and mediate important cell signaling to maintain podocyte health. In this review, we will focus on slit diaphragm proteins such as nephrin, podocin, TRPC6/5, as well as cytoskeletal proteins Rho/small GTPases and synaptopodin and their respective roles in participating in the pathogenesis of proteinuric kidney diseases. Furthermore, we will summarize the potential therapeutic options targeting the podocyte to treat this group of kidney diseases.

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.

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.

Role of kidney biomarkers [Kidney injury molecule-1, Calbindin, Interleukin-18 and Monocyte chemoattractant protein-1] in HIV associated pre-eclampsia

OBJECTIVE

Both HIV infection and pre-eclampsia (PE) are associated with considerable maternal mortality in South Africa. This study was designed to compare the urinary levels of kidney injury molecule-1 (KIM-1), calbindin, interleukin-18 (IL-18), and monocyte chemoattractant protein-1 (MCP-1) in HIV associated normotensive and preeclamptic pregnancies.

METHODS

Following ethical approval and written consent, urine samples were collected from HIV negative (HIV -ve) normotensive pregnant (n = 19), HIV positive (HIV +ve) normotensive pregnant (n = 19), HIV -ve pre-eclamptic (n = 19) and HIV +ve pre-eclamptic (n = 19) women. The concentrations of KIM-1, calbindin, IL-18 and MCP-1 were assessed using the Bioplex technology.

RESULTS

In contrast to IL-18 (p > 0.05) and MCP-1 (p > 0.05), the concentrations of KIM-1 (p = 0.02) and calbindin (p = 0.02) were significantly higher in PE compared to normotensive pregnancies, irrespective of HIV status. Based on HIV status, all 4 analytes were similar between HIV+ve and HIV-ve groups. Urinary KIM-1 levels in the HIV -ve pre-eclamptics were significantly higher than those in the HIV -ve women with normal pregnancies (p = 0.007). The maternal hypertension and/or HIV profile has no marked impact on the fetal weight.

CONCLUSION

Our results demonstrate an increase in the urinary level of kidney injury molecule-1 and calbindin in PE, implicating their possible value as biomarkers of kidney injury. We observed no differences in the levels of KIM-1, IL-18, MCP-1 and calbindin based on HIV status. We propose that studies with larger sample sizes using these markers be conducted to establish their use as markers of diagnosing kidney injury in PE.

Role of ESAT-6 in renal injury by regulating microRNA-155 expression via TLR4/MyD88 signaling pathway in mice with Mycobacterium tuberculosis infection

The study aims to investigate the underlying mechanism involved in the early secretory antigenic target-6 (ESAT-6) in renal injury through regulation of the expression of miR-155 through the oll-like receptor (TLR)-4 (TLR4)/myeloid differentiation factor 88 (MyD88) signaling pathway in Mycobacterium tuberculosis (MTB)-infected mice. Sixty C57BL/6 mice with MTB-induced renal injury were randomly assigned into control, MTB, mimic, inhibitor, inhibitor + ESAT6, and inhibitor + ESAT6 + TAK242 groups. Body weight, the ratio of kidney weight to body weight (Kw/Bw), blood urea nitrogen (BUN), and serum creatinine (Scr) of mice were measured. Flow cytometry was used to detect renal activation in mice. Expressions of miR-155 and ESAT6 were detected by quantitative real-time PCR (qRT-PCR), and Western blotting was used to examine the expressions of ESAT6, TLR4, and MyD88. Expressions of tumor necrosis factor-α (TNF-α), interleukin-17 (IL-17), and interferon-γ (IFN-γ) were measured by qRT-PCR and ELISA. Compared with the control group, the BUN and Scr levels as well as the expression levels of miR-155, TLR4, MyD88, TNF-α, IL-17, and IFN-γ increased, while Kw/Bw decreased in the MTB and mimic groups. In comparison with the MTB group, the above indexes except Kw/Bw were elevated in the mimic group, but were reduced in the inhibitor group, while the Kw/Bw dropped in the mimic group but increased in the inhibitor group. Compared with the inhibitor group, the Kw/Bw decreased while the rest of the indexes increased in the inhibitor + ESAT6 group. ESAT6 may induce renal injury by promoting miR-155 expression through the TLR-4/MyD88 signaling pathway in MTB-infected mice.

New Insights into the Role of Matrix Metalloproteinases in Preeclampsia

Preeclampsia is a severe pregnancy complication globally, characterized by poor placentation triggering vascular dysfunction. Matrix metalloproteinases (MMPs) exhibit proteolytic activity implicated in the efficiency of trophoblast invasion to the uterine wall, and a dysregulation of these enzymes has been linked to preeclampsia. A decrease in MMP-2 and MMP-9 interferes with the normal remodeling of spiral arteries at early pregnancy stages, leading to the initial pathophysiological changes observed in preeclampsia. Later in pregnancy, an elevation in MMP-2 and MMP-9 induces abnormal release of vasoactive factors conditioning hypertension. Although these two enzymes lead the scene, other MMPs like MMP-1 and MMP-14 seem to have a role in this pathology. This review gathers published recent evidence about the implications of different MMPs in preeclampsia, and the potential use of these enzymes as emergent biomarkers and biological therapeutic targets, focusing on studies involving human subjects.

Ratio of matrix metalloproteinase-2 to -9 is a more accurate predictive biomarker in women with suspected pre-eclampsia

Pre-eclampsia (PE) is a condition unique to pregnancy, and abnormal expression of matrix metalloproteinases (MMPs) has been implicated in its pathogenesis. We aimed to evaluate the reliability of plasma levels of MMP-2, MMP-9 and their relative ratio in predicting PE. A total of 318 women with suspected PE were recruited for the study, who were subsequently either cleared or diagnosed of PE and grouped accordingly. Their baseline characteristics were compared. Blood samples were also collected from all participants, to determine the plasma levels of MMP-2 and MMP-9. The predictive values of levels of MMP-2 and MMP-9, as well as their ratio, were analyzed using the receiver operating characteristic (ROC) curve. Either MMP-2 or MMP-9 alone did not exhibit any obvious differences between normal and PE pregnancies. However the ratio of MMP-2/MMP-9 was significantly higher in PE-affected pregnancy than normal control group. ROC curve analysis also indicated that the MMP-2/MMP-9 ratio provided better compromise between specificity and sensitivity in distinguishing PE from normal pregnancies, than either of the two MMPs alone. MMP-2/MMP-9 ratio is a more accurate biomarker to predict PE than either MMP-2 or MMP-9 alone.

Matrix metalloproteinase multiplex screening identifies increased MMP-2 urine concentrations in women predicted to develop 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

The objective of this study is to evaluate the usefulness of nine urinary metalloproteinases to predict the risk of preeclampsia development.

METHODS

MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-10, MMP-12 and MMP-13 were analyzed in urine (early-pregnancy) from 17 women predicted to develop preeclampsia and 48 controls using the Bio-Plex Pro-Human MMP panel (Bio-Rad, Hercules, CA).

RESULTS

Urinary MMP-2 showed differences between groups which allowed us to calculate an increased risk for PE development of up to 20 times among the study population.

CONCLUSION

Increased urinary concentration of MMP-2 at 12 and 16 weeks of gestation predicted an increased risk of developing preeclampsia in the study population.

Vascular adaptation in pregnancy and endothelial dysfunction in preeclampsia

Maternal vascular adaptation to pregnancy is critically important to expand the capacity for blood flow through the uteroplacental unit to meet the needs of the developing fetus. Failure of the maternal vasculature to properly adapt can result in hypertensive disorders of pregnancy such as preeclampsia (PE). Herein, we review the endocrinology of maternal adaptation to pregnancy and contrast this with that of PE. Our focus is specifically on those hormones that directly influence endothelial cell function and dysfunction, as endothelial cell dysfunction is a hallmark of PE. A variety of growth factors and cytokines are present in normal vascular adaptation to pregnancy. However, they have also been shown to be circulating at abnormal levels in PE pregnancies. Many of these factors promote endothelial dysfunction when present at abnormal levels by acutely inhibiting key Ca²⁺ signaling events and chronically promoting the breakdown of endothelial cell-cell contacts. Increasingly, our understanding of how the contributions of the placenta, immune cells, and the endothelium itself promote the endocrine milieu of PE is becoming clearer. We then describe in detail how the complex endocrine environment of PE affects endothelial cell function, why this has contributed to the difficulty in fully understanding and treating this disorder, and how a focus on signaling convergence points of many hormones may be a more successful treatment strategy.