Longitudinal characterization of renal proximal tubular markers in normotensive and preeclamptic pregnancies

Urine excretion of C3dg and sC5b-9 coincide with proteinuria and development of preeclampsia in pregnant women with type-1 diabetes

OBJECTIVE

Pregnant women with type-1 diabetes have an increased risk of preeclampsia with kidney injury and cardiovascular complications. Urine excretion of plasmin and soluble membrane attack complex (sC5b-9) is elevated in severe preeclampsia. We hypothesized a coupling between these events and that active plasmin promotes intratubular complement activation and membrane deposition.

METHODS

Stored urine and plasma samples from pregnant women with type-1 diabetes (n = 88) collected at gestational weeks 12, 20, 28, 32, 36 and 38 were used. In the cohort, 14 women developed preeclampsia and were compared with 16 nonpreeclampsia controls.

RESULTS

Urine C3dg and sC5b-9-associated C9 neoantigen/creatinine ratios increased and were significantly higher in women who developed preeclampsia. Plasma concentrations did not change with gestation. Urine plasmin(ogen) correlated to urine C3dg (r = 0.51, P < 0.001) and C9 neoantigen (r = 0.68, P < 0.001); urine albumin correlated to C3dg (r = 0.44, P < 0.001) and C9 (r = 0.59, P < 0.001). Membrane-associated C3dg and C9 neoantigen was detected in urinary extracellular vesicles from patients but not controls at 36 weeks. Receiver operating characteristic curves showed that C3dg and C9 neoantigen were inferior to albumin as predictive biomarkers for preeclampsia.

CONCLUSION

In preeclampsia, urinary excretion of activated complement relates significantly to albuminuria and to plasmin(ogen) but not to activation in plasma. Intratubular complement activation in preeclampsia is a postfiltration event tightly related to proteinuria/plasminogenuria and a possible mechanistic link to cellular damage and kidney injury.

Acute Kidney Injury in Severe Preeclamptic Patients Admitted to Intensive Care Unit: Epidemiology and Role of Serum Neutrophil Gelatinase-associated Lipocalcin

Background

Patients with preeclampsia admitted to the intensive care unit (ICU) may have risk factors for acute kidney injury (AKI). Although the use of neutrophil gelatinase-associated lipocalcin (NGAL) to predict AKI is previously validated, we could locate only scanty data regarding the epidemiology of AKI and role of NGAL in preeclamptic patients admitted to ICU.

Methods

Patients with preeclampsia admitted to our ICU were included. The incidence and severity of AKI during the entire ICU stay were assessed using kidney disease improving global outcomes criteria, while the a priori risk factors and serum NGAL were also evaluated.

Results

A total of 52 preeclamptic patients admitted to ICU were included, among whom the majority had eclampsia (75%). AKI developed in 25 (48.1%) patients with stages 1, 2, and 3 in 56, 36, and 8%, respectively. The incidence of sepsis (16 vs 0%), shock (40 vs 7.4%), and anemia (84 vs 59.3%) was significantly greater in patients with AKI (p < 0.05). ICU mortality (28 vs 3.7%), duration of ICU, and hospital stay were significantly higher in patients who developed AKI (p < 0.05). There was no association of serum NGAL [274 (240–335) ng/mL] with AKI or the mortality (p = 0.725, 0.861); there was, however, a significant discriminatory value for eclampsia [p = 0.019; area under curve = 0.736 (95% confidence interval: 0.569–0.904)].

Conclusions

Although AKI is common among patients with preeclampsia admitted to ICU, serum NGAL does not predict its occurrence.

How to cite this article

Tyagi A, Yadav P, Salhotra R, Das S, Singh PK, Garg D. Acute Kidney Injury in Severe Preeclamptic Patients Admitted to Intensive Care Unit: Epidemiology and Role of Serum Neutrophil Gelatinase-associated Lipocalcin. Indian J Crit Care Med 2021;25(9):1013–1019.

Pregnant alpha-1-microglobulin (A1M) knockout mice exhibit features of kidney and placental damage, hemodynamic changes and intrauterine growth restriction

Alpha-1-microglobulin (A1M) is an antioxidant previously shown to be elevated in maternal blood during pregnancies complicated by preeclampsia and suggested to be important in the endogenous defense against oxidative stress. A knockout mouse model of A1M (A1Mko) was used in the present study to assess the importance of A1M during pregnancy in relation to the kidney, heart and placenta function. Systolic blood pressure (SBP) and heart rate (HR) were determined before and throughout gestation. The morphology of the organs was assessed by both light and electron microscopy. Gene expression profiles relating to vascular tone and oxidative stress were analyzed using RT-qPCR with validation of selected gene expression relating to vascular tone and oxidative stress response. Pregnant age-matched wild type mice were used as controls. In the A1Mko mice there was a significantly higher SBP before pregnancy that during pregnancy was significantly reduced compared to the control. In addition, the HR was higher both before and during pregnancy compared to the controls. Renal morphological abnormalities were more frequent in the A1Mko mice, and the gene expression profiles in the kidney and the heart showed downregulation of transcripts associated with vasodilation. Simultaneously, an upregulation of vasoconstrictors, blood pressure regulators, and genes for osmotic stress response, ion transport and reactive oxygen species (ROS) metabolism occurred. Fetal weight was lower in the A1Mko mice at E17.5. The vessels in the labyrinth zone of the placentas and the endoplasmic reticulum in the spongiotrophoblasts were collapsed. The gene profiles in the placenta showed downregulation of antioxidants, ROS metabolism and oxidative stress response genes. In conclusion, intact A1M expression is necessary for the maintenance of normal kidney, heart as well as placental structure and function for a normal pregnancy adaptation.

Clinical adoption of Nephrocheck® in the early detection of acute kidney injury

Acute kidney injury is a common complication of acute illnesses and is associated with increased morbidity and mortality. Over the past years several acute kidney injury biomarkers for diagnostication, decision-making processes, and prognosis of acute kidney injury and its outcomes have been developed and validated. Among these biomarkers, tissue inhibitor of metalloproteinase-2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP7), the so-called cell cycle arrest biomarkers, showed a superior profile of accuracy and stability even in patients with substantial comorbidities. Therefore, in 2014, the US Food and Drug Administration approved the use of the product of TIMP-2 and IGFBP7 ([TIMP-2] × [IGFBP7]), known as cell cycle arrest biomarkers, to aid critical care physicians and nephrologists in the early prediction of acute kidney injury in the critical care setting. To date, Nephrocheck® is the only commercially available test for [TIMP-2] × [IGFBP7]. In this narrative review, we describe the growing clinical and investigational momentum of biomarkers, focusing on [TIMP-2] × [IGFBP7], as one of the most promising candidate biomarkers. Additionally, we review the current state of clinical implementation of Nephrocheck®.

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.

Systemic Outcomes of (Pyr1)-Apelin-13 Infusion at Mid-Late Pregnancy in a Rat Model with Preeclamptic Features

Preeclampsia is a syndrome with diverse clinical presentation that currently has no cure. The apelin receptor system is a pleiotropic pathway with a potential for therapeutic targeting in preeclampsia. We established the systemic outcomes of (Pyr¹)-apelin-13 administration in rats with preeclamptic features (TGA-PE, female transgenic for human angiotensinogen mated to male transgenic for human renin). (Pyr¹)-apelin-13 (2 mg/kg/day) or saline was infused in TGA-PE rats via osmotic minipumps starting at day 13 of gestation (GD). At GD20, TGA-PE rats had higher blood pressure, proteinuria, lower maternal and pup weights, lower pup number, renal injury, and a larger heart compared to a control group (pregnant Sprague-Dawley rats administered vehicle). (Pyr¹)-apelin-13 did not affect maternal or fetal weights in TGA-PE. The administration of (Pyr¹)-apelin-13 reduced blood pressure, and normalized heart rate variability and baroreflex sensitivity in TGA-PE rats compared to controls. (Pyr¹)-apelin-13 increased ejection fraction in TGA-PE rats. (Pyr¹)-apelin-13 normalized proteinuria in association with lower renal cortical collagen deposition, improved renal pathology and lower immunostaining of oxidative stress markers (4-HNE and NOX-4) in TGA-PE. This study demonstrates improved hemodynamic responses and renal injury without fetal toxicity following apelin administration suggesting a role for apelin in the regulation of maternal outcomes in preeclampsia.

Protective effect of dexmedetomidine on kidney injury of parturients with preeclampsia undergoing cesarean section: a randomized controlled study

The present study aimed to elucidate the effects of dexmedetomidine on kidney injury of parturients with preeclampsia (PE) undergoing cesarean section. Total 134 cesarean delivery women with PE were randomly divided into intervention group (IG) and control group (CG). Both groups underwent combined spinal and epidural anesthesia (CSEA), the IG was treated with 0.4 μg/(kg·min) dexmedetomidine for 10 min before surgery. The CG was treated with equivalent saline. Heart rate (HR), blood pressure, oxygen saturation (SpO₂) of the two groups were measured at different time point after administration. Level of inflammatory factors were detected by enzyme-linked immunosorbent assay (ELISA). Visual analogue score (VAS), Ramsay sedation score (RSS), and kidney injury related indexes were evaluated at different time points. The plasma-drug concentration of patients was determined by High Performance Liquid Chromatography (HPLC) method. Compared with CG, HR, PE, and diastolic blood pressure (DBP) showed lower level while SpO₂ showed higher level in IG. Furthermore, expression of tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), and IL-10 in IG was decreased after drug administration, the contents of β2-MG, KIM-1 and urine protein were also decreased in contrast to the CG (all P<0.05). Besides, VAS score was decreased but Ramsay score was increased in the IG (both P<0.05). The results of HPLC showed that the half life of dexmedetomidine was about 20 min and it is speculated that the drug can be quickly metabolized within 24 h. Dexmedetomidine exerted protective effects on kidney injury of parturients with PE undergoing cesarean section.

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.

Why kidneys fail post-partum: a tubulocentric viewpoint

Kidneys may fail post-partum in a number of circumstances due, for example, to post-partum haemorrhage, preeclampsia, amniotic fluid embolism or septic abortion. All these conditions in pregnancy and post partum represent a threat not only to the endothelium but also to the renal tubular epithelium, and as such may lead to rapid and also irreversible impairment of the renal function. This paper is a non-systematic review of the literature and of our experience, in which we discuss the main open issues on kidney disease in pregnancy and following delivery, in particular as regards tubular damage, with the aim to help reasoning on acute kidney injury (AKI) following delivery. The review will emphasize the often under-estimated importance of the tubular epithelium in the peri-partum period and will: (1) describe the main characteristics of the renal tissues around delivery; (2) define pregnancy-related AKI according to recent Kidney Disease/Improving Global Outcome (KDIGO) guidelines; (3) discuss the most common circumstances of post-partum AKI; and (4) describe the input expected from urinalysis, renal imaging and kidney biopsy.

Subclinical First Trimester Renal Abnormalities Are Associated With Preeclampsia in Normoalbuminuric Women With Type 1 Diabetes

OBJECTIVE

This study was conducted to determine the utility of tubular (urinary/plasma neutrophil gelatinase-associated lipocalin [NGAL] and urinary kidney injury molecule 1 [KIM-1]) and glomerular (estimated glomerular filtration rate [eGFR]) biomarkers in predicting preeclampsia (PE) in pregnant women with type 1 diabetes mellitus (T1DM) who were free of microalbuminuria and hypertension at the first trimester.

RESEARCH DESIGN AND METHODS

This was a prospective study of T1DM pregnancy. Maternal urinary and plasma NGAL, urinary KIM-1 (ELISA of frozen samples), and eGFR (Chronic Kidney Disease Epidemiology Collaboration equation) were determined at three study visits (V1: 12.4 ± 1.8; V2: 21.7 ± 1.4; V3: 31.4 ± 1.5 weeks' gestation [mean ± SD]) in 23 women with T1DM with subsequent PE (DM+PE+), 24 who remained normotensive (DM+PE-), and, for reference, in 19 normotensive pregnant women without diabetes (DM-). The groups with diabetes were matched for age, diabetes duration, and parity. All subjects were normotensive and free of microalbuminuria or albuminuria at V1. All study visits preceded the onset of PE.

RESULTS

Urinary creatinine-corrected NGAL (uNGALcc, ng/mg) was significantly elevated at V1 in DM+PE+ vs. DM+PE- women (P = 0.01); this remained significant after exclusion of leukocyte-positive samples (5 DM+PE+ and 2 DM+PE-) (P = 0.02). Accounting for BMI, HbA_1c, and total daily insulin dose, a doubling of uNGALcc at V1 conferred a sevenfold increase in risk for PE (P = 0.026). In contrast, neither plasma NGAL nor urinary KIM-1 predicted PE. Also at V1, eGFR was elevated in DM+PE+ vs. DM+PE- (P = 0.04).

CONCLUSIONS

Early tubular and glomerular dysfunction may predict PE in first trimester women with T1DM, even if free of microalbuminuria. These data suggest that subclinical renal tubular and glomerular injury, if present early in pregnancy, may predispose women with T1DM to PE.

The Complement System and Preeclampsia

PURPOSE OF REVIEW

Preeclampsia affects 3-4% of pregnancies with few treatment options to reduce maternal and fetal harm. Recent evidence that targeting the complement system may be an effective therapeutic strategy in prevention or treatment of preeclampsia will be reviewed.

RECENT FINDINGS

Studies in humans confirm the safety and efficacy of C5 blockade in complement-mediated disorders of pregnancy, including preeclampsia. Animal models mimic the placental abnormalities and/or the maternal symptoms which characterize preeclampsia. These models in mouse and rat have defined a role for complement and its regulators in placental dysfunction, hypertension, proteinuria, endothelial dysfunction, fetal growth restriction, and angiogenic imbalance, thus informing future human studies. Targeting excessive complement activation, particularly the terminal complement complex (C5b-9) and C5a may be an effective strategy to prolong pregnancy in women with preeclampsia. Continued research is needed to identify the initiator(s) of activation, the pathways involved, and the key component(s) in the pathophysiology to allow development of safe and effective therapeutics to target complement without compromising its role in homeostasis and host defense.