Urinary excretion of nephrin in patients with severe preeclampsia. Urinary nephrin in preeclampsia

Urinary nephrin-a potential marker of early glomerular injury: a systematic review and meta-analysis

BACKGROUND

Both early recognition of glomerular injury and diagnosis of renal injury remain important problems in clinical settings, and current diagnostic biomarkers have limitations. The aim of this review was to determine the diagnostic accuracy of urinary nephrin for detecting early glomerular injury.

METHODS

A search was conducted through electronic databases for all relevant studies published until January 31, 2022. The methodological quality was evaluated using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Pooled sensitivity, specificity, and other estimates of diagnostic accuracy were determined using a random effect model. The Summary Receiver Operating Characteristics (SROC) was used to pool the data and to estimate the area under the curve (AUC).

RESULTS

The meta-analysis included 15 studies involving 1587 participants. Overall, the pooled sensitivity of urinary nephrin for detecting glomerular injury was 0.86 (95% CI 0.83-0.89) and specificity was 0.73 (95% CI 0.70-0.76). The AUC-SROC to summarise the diagnostic accuracy was 0.90. As a predictor of preeclampsia, urinary nephrin showed a sensitivity of 0.78 (95% CI 0.71-0.84) and specificity of 0.79 (95% CI 0.75-0.82), and as a predictor of nephropathy the sensitivity was 0.90 (95% CI 0.87-0.93), and specificity was 0.62 (95% CI 0.56-0.67). A subgroup analysis using ELISA as a method of diagnosis showed a sensitivity of 0.89 (95% CI 0.86-0.92), and a specificity of 0.72 (95% CI 0.69-0.75).

CONCLUSION

Urinary nephrin may be a promising marker for the detection of early glomerular injury. ELISA assays appear to provide reasonable sensitivity and specificity. Once translated into clinical practice, urinary nephrin could provide an important addition to a panel of novel markers to help in the detection of acute and chronic renal injury.

Urinary Nephrin Levels Among Pregnant Women With Preeclampsia in Lagos, Southwest Nigeria: An Analytical Cross-Sectional Study

BACKGROUND

Hypertensive disorders in pregnancy are one of the leading causes of maternal and perinatal morbidity and mortality worldwide. The clinical utility of urinary nephrin as a diagnostic biomarker of preeclampsia is currently of research interest. However, this is yet to gain significant traction within clinical settings.

OBJECTIVES

We evaluated the association between maternal urinary nephrin levels and the occurrence and severity of preeclampsia among pregnant women in Lagos, Nigeria.

DESIGN

We conducted an analytical cross-sectional study involving pregnant women diagnosed with preeclampsia as well as their age- and gestational-age-matched normotensive counterparts. We tested the association between high maternal urinary nephrin levels and the occurrence of preeclampsia without and with severe features. P < 0.05 was reported as statistically significant.

RESULTS

The study showed that for every unit increase in urinary nephrin levels, the odds of preeclampsia increased by about ninefold (adjusted Odds ratio = 8.9, 95% confidence interval: 2.8-29.2, P < 0.001). The levels of urinary nephrin increased steadily with increasing severity of the disease: 1.9 ± 0.8 ng/mL in preeclampsia without severe features, 2.7 ± 0.7 ng/mL in preeclampsia with at least one severe feature, and 3.3 ±1.1 ng/mL in eclampsia.

CONCLUSION

There was an association between elevated levels of urinary nephrin and preeclampsia and its severe variant. However, there is a need for more robust studies with a longitudinal characterization of urinary nephrin levels to establish causal relationships with preeclampsia, explore other potential risk factors of preeclampsia, and define the clinical usefulness of urinary nephrin as a potentially reliable and accurate predictive marker of preeclampsia among women in low- and middle-income countries (LMIC) settings.

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.

The Level of Serum and Urinary Nephrin in Normal Pregnancy and Pregnancy with Subsequent Preeclampsia

PURPOSE

The aim of this study was to evaluate serum and urinary nephrin levels of normal pregnancy to establish a standard reference value and to compare them with patients who subsequently developed preeclampsia (PE).

MATERIALS AND METHODS

In this prospective study, 117 healthy singleton pregnancies were enrolled between 6 to 20 weeks of gestation at 2 participating medical centers during October 2010 to March 2012. Urine and serum samples were collected at the time of enrollment, each trimester, and at 4 to 6 weeks postpartum. Enzyme-linked immunosorbent assay for nephrin was performed and samples from patients who subsequently developed PE were compared to the normal patients.

RESULTS

Of 117 patients initially enrolled, 99 patients delivered at the study centers and of those patients, 12 (12.1%) developed PE at a median gestational age of 34⁺⁴ weeks (range 29⁺⁵-36⁺⁶). In the normal patients (n=68), serum nephrin level decreased and urinary nephrin level increased during the latter of pregnancy. In 12 patients who subsequently developed PE, a significant rise in the 3rd trimester serum and urinary nephrin levels, compared to the controls, was observed (p<0.001), and this increase occurred 9 days prior to the onset of clinical disease.

CONCLUSION

As the onset of PE was preceded by the rise in the serum and urinary nephrin in comparison to normal pregnancy, serum and urinary nephrin may be a useful predictive marker of PE.

Original Research: Potential of urinary nephrin as a biomarker reflecting podocyte dysfunction in various kidney disease models

Urinary nephrin is a potential non-invasive biomarker of disease. To date, however, most studies of urinary nephrin have been conducted in animal models of diabetic nephropathy, and correlations between urinary nephrin-to-creatinine ratio and other parameters have yet to be evaluated in animal models or patients of kidney disease with podocyte dysfunction. We hypothesized that urinary nephrin-to-creatinine ratio can be up-regulated and is negatively correlated with renal nephrin mRNA levels in animal models of kidney disease, and that increased urinary nephrin-to-creatinine ratio levels are attenuated following administration of glucocorticoids. In the present study, renal nephrin mRNA, urinary nephrin-to-creatinine ratio, urinary protein-to-creatinine ratio, and creatinine clearance ratio were measured in animal models of adriamycin nephropathy, puromycin aminonucleoside nephropathy, anti-glomerular basement membrane glomerulonephritis, and 5/6 nephrectomy. The effects of prednisolone on urinary nephrin-to-creatinine ratio and other parameters in puromycin aminonucleoside (single injection) nephropathy rats were also investigated. In all models tested, urinary nephrin-to-creatinine ratio and urinary protein-to-creatinine ratio increased, while renal nephrin mRNA and creatinine clearance ratio decreased. Urinary nephrin-to-creatinine ratio exhibited a significant negative correlation with renal nephrin mRNA in almost all models, as well as a significant positive correlation with urinary protein-to-creatinine ratio and a significant negative correlation with creatinine clearance ratio. Urinary protein-to-creatinine ratio exhibited a significant negative correlation with renal nephrin mRNA. Following the administration of prednisolone to puromycin aminonucleoside (single injection) nephropathy rats, urinary nephrin-to-creatinine ratio was significantly suppressed and exhibited a significant positive correlation with urinary protein-to-creatinine ratio. In addition, the decrease in number of glomerular Wilms tumor antigen-1-positive cells was attenuated, and urinary nephrin-to-creatinine ratio exhibited a significant negative correlation in these cells. In conclusion, these results suggest that urinary nephrin-to-creatinine ratio level is a useful and reliable biomarker for predicting the amelioration of podocyte dysfunction by candidate drugs in various kidney disease models with podocyte dysfunction. This suggestion will also be validated in a clinical setting in future studies.

Biomarker of Early Glomerular Injury in Pre-eclampsia

OBJECTIVES

Nephrin is an integral part of podocytes that together with endothelial cells and the basement form the glomerular filtration barrier. Placental ischemia triggers a cascade of events that ultimately result in endothelial malfunction, hypertension, podocytopathy and fetal compromise.

METHODS

We review the literature to determine if urine nephrin measurements could serve as a useful biomarker to detect early podocyte injury in pre-eclampsia.

RESULTS

Our search identifies eight studies published to date. The findings of these studies demonstrate that urine nephrin excretion plays a critical role in the pathogenesis of proteinuria during pre-eclampsia and that this is a good indicator of glomerular injury.

CONCLUSION

There is thus an urgent need for a large multi-centre clinical study using standardized recruitment criteria to determine the full potential of this biomarker in clinical practice.

Expression of nephrin in the human placenta and fetal membranes

Nephrin is the signature molecule in the podocyte of the glomerulus that forms the renal slit diaphragm, the main functional unit of the glomerulus. The present study focused on the expression of nephrin in the human placenta, which may also have a role in filtration and the maintenance of homeostasis in the kidneys. A total of nine placentas from normal healthy pregnant females at full term were investigated. Reverse transcription-quantitative polymerase chain reaction, western blotting and immunofluorescence were performed. The expression of nephrin mRNA was relatively increased in the chorion compared with that in the villi and the amnion. The nephrin gene was detected in the villous cytotrophoblast cells and the endothelium of the intravillous vessels. It was also present in the chorionic and amniotic membranous lining, with its distribution being particularly dense in the amniocytes. The identification of nephrin in the human placenta, particularly at the maternal‑fetal interface, provides a novel insight into the molecular basis of the selective permeability of the placental barrier, which requires further elucidation.

ELISA analysis of urinary nephrin and podocalyxin standardized by aquaporin-2 in adult patients with nephrotic syndrome

OBJECTIVE

To investigate urinary nephrin and podocalyxin standardized by aquaporin (AQP)-2 using the enzyme-linked immunosorbent assay (ELISA) method in adult nephrotic syndrome (NS) patients.

METHODS

In 107 adult NS patients (27 proliferative nephritis, 77 non-proliferative, and 3 amyloidosis) undergoing renal biopsy, urinary nephrin, podocalyxin and AQP2 were measured by ELISA. Urinary nephrin and podocalyxin were standardized by AQP2 (neph/AQP and PCX/AQP) and values were compared with 11 healthy controls.

RESULTS

Urinary neph/AQP correlated positively to PCX/AQP (r = 0.51, p < 0.001). Urinary neph/AQP and PCX/AQP were lower in controls than NS patients. Both proliferative and non-proliferative NS patients excreted high urinary neph/AQP and PCX/AQP without a significant difference between them (p > 0.05). Patients with focal segmental glomerular sclerosis (FSGS) excreted higher urinary neph/AQP (p = 0.09) and PCX/AQP (p < 0.05) compared to the other patients. Urinary neph/AQP and PCX/AQP were increased in the immunoglobulin M nephropathy patients. Amyloidosis patients excreted lower neph/AQP and PCX/AQP. The sensitivity was 0.87 and specificity 0.37 when the neph/AQP borderline value of 0.16 was adopted [area under the curve (AUC) = 0.61]. The sensitivity was 0.74 and specificity 0.61 when the PCX/AQP borderline value was 3.06 (AUC = 0.69).

CONCLUSIONS

Urinary neph/AQP and PCX/AQP are increased in NS patients, with FSGS patients showing the highest levels. To distinguish FSGS from other NS forms, the measurement of urinary PCX/AQP may be a practical method, and superior to neph/AQP.

Urinary nephrin: A new predictive marker for pregnancies with preeclampsia and small-for-gestational age infants

Objective

The objective of this study was to determine the differences in urinary nephrin among controls, gravidas with preeclampsia (PE), and small-for-gestational age (SGA) infants. We also determined whether or not maternal urinary concentrations of nephrin are associated with the subsequent development of PE and SGA infants.

Methods

We analyzed maternal urinary levels of nephrin in women who were normal controls (n=50), women who were delivered SGA infants (n=40), and gravidas with PE (n=33) in the first, second and third trimesters. Urinary nephrin concentrations were measured with nephrin enzyme-linked immunosorbent assay kits.

Results

The levels of urinary nephrin were higher in gravida developing preeclampsia or SGA than in controls after adjusting serum creatinine (P<0.05 for both). Maternal urine concentrations of nephrin were higher in pregnancies complicated by SGA and PE in the third trimester (P<0.05), and also higher in pregnancies complicated by SGA in the first trimester (P<0.05). The sensitivity and specificity of nephrin in predicting SGA from normal pregnancies were 67% and 89% in the first trimester, 60% and 79% in the second trimester, and 80% and 84% in the third trimester, respectively. The sensitivity and specificity of nephrin in predicting PE from normal pregnancies were 67% and 83% in the first trimester and 73% and 79% in the third trimester, respectively.

Conclusion

We suggest that urinary nephrin can be used as an early marker in pregnancies at risk for developing PE and SGA infants.