Kidney NGAL is a novel early marker of acute injury following transplantation

Furosemide attenuates tubulointerstitial injury and allows functional testing of porcine kidneys during normothermic machine perfusion

BACKGROUND

Normothermic machine perfusion (NMP) is a promising pretransplant kidney quality assessment platform, but it remains crucial to increase its diagnostic potential while ensuring minimal additional injury to the already damaged kidney. Interventions that alter tubular transport can influence renal function and injury during perfusion. This study aimed to determine whether furosemide and desmopressin affect renal function and injury during NMP.

METHODS

Eighteen porcine kidneys (n = 6 per group) were subjected to 30 min of warm ischemia and 4 h of oxygenated hypothermic perfusion before being subjected to 6 h of NMP. Each organ was randomized to receive no drug, furosemide (750 mg), or desmopressin (16 μg) during NMP.

RESULTS

Compared with the other groups, the addition of furosemide resulted in significantly increased urine output, fractional excretion of sodium and potassium, and urea clearance during NMP. Urinary neutrophil gelatinase-associated lipocalin levels decreased significantly with furosemide supplementation compared with the other groups. The addition of desmopressin did not result in any significantly different outcome measurements compared with the control group.

CONCLUSIONS

This study showed that the addition of furosemide affected renal function while attenuating tubulointerstitial injury during NMP. Therefore, furosemide supplementation may provide renal protection and serve as a functional test for pretransplant kidney viability assessment during NMP.

Renal dysfunction during treatment of chronic hepatitis B with tenofovir disoproxyl fumarate and associated risk factors

OBJECTIVES

To analyze the evolution of glomerular filtration rate (GFR) and the presence of renal tubular dysfunction during the treatment of chronic hepatitis B virus (HBV) infection with tenofovir disoproxil fumarate (TDF) and to determine the risk factors involved.

METHODS

Retrospective cohort observational study of adults with chronic hepatitis B. Exclusion: hepatitis C virus-HBV coinfection, diabetes, baseline GFR less than 60 ml/min. Measurements of serum and urinary creatinine and phosphate; urinary albumin, retinol-binding protein (RBP) and neutrophil gelatinase-associated lipocalin (NGAL) were performed. Univariate and multivariate analyses tracked factors associated with worsening GFR.

RESULTS

A total of 120 individuals were included: 35% NAÏVE (G1); 49.2% HBV using TDF (G2); 15.8% HBV-HIV using TDF (G3); 63.3% men; 60.8% white; 30% hypertensive. Average age was 50.5 years (SD ± 12.9 years). Reactive HBeAg predominated in G3 ( P  < 0.001) and cirrhosis in G2 ( P  < 0.036). NGAL was elevated in 5.3% of cases (G1 = 3.2%; G2 = 8.7%; G3 = 0%; P  = 0.582), RBP in 6.7% (G1, G3 = 0%; G2 = 13.6%; P  = 0.012), urinary phosphate/creatinine ratio in 16.2% (G1 = 15.2%; G2 = 14.5%; G3 = 23.5%; P  = 0.842) and urinary albumin/creatinine ratio in 12.9% (G1 = 12.2%; G2 = 10.7%; G3 = 21.1%; P  = 0.494). Worsening of renal function occurred in 22.5% of the population (G1 = 11.9%; G2 = 28.8%; G3 = 26.3%; P  = 0.122), independently associated only with systemic arterial hypertension [adjusted odds ratio (AOR) = 4.14; P  = 0.008], but not to TDF (AOR = 2.66; P  = 0.110) or male sex (AOR = 2.39; P  = 0.135). However, the concomitance of these variables generated a high estimated risk for this outcome (51%).

CONCLUSIONS

Renal tubular dysfunction was uncommon according to NGAL, RBP or urinary phosphate/creatinine ratio. TDF was not an independent factor for worsening renal function, significantly associated only with systemic arterial hypertension. However, in hypertensive men, the use of TDF should be monitored.

Plasma NGAL levels in stable kidney transplant recipients and the risk of allograft loss

BACKGROUND

The objective of this study was to investigate the utility of neutrophil gelatinase-associated lipocalin (NGAL) and calprotectin (CPT) to predict long-term graft survival in stable kidney transplant recipients (KTR).

METHODS

A total of 709 stable outpatient KTR were enrolled >2 months post-transplant. The utility of plasma and urinary NGAL (pNGAL, uNGAL) and plasma and urinary CPT at enrollment to predict death-censored graft loss was evaluated during a 58-month follow-up.

RESULTS

Among biomarkers, pNGAL showed the best predictive ability for graft loss and was the only biomarker with an area under the curve (AUC) > 0.7 for graft loss within 5 years. Patients with graft loss within 5 years (n = 49) had a median pNGAL of 304 [interquartile range (IQR) 235-358] versus 182 (IQR 128-246) ng/mL with surviving grafts (P < .001). Time-dependent receiver operating characteristic analyses at 58 months indicated an AUC for pNGAL of 0.795, serum creatinine-based Chronic Kidney Disease Epidemiology Collaboration estimated glomerular filtration rate (eGFR) had an AUC of 0.866. pNGAL added to a model based on conventional risk factors for graft loss with death as competing risk (age, transplant age, presence of donor-specific antibodies, presence of proteinuria, history of delayed graft function) had a strong independent association with graft loss {subdistribution hazard ratio (sHR) for binary log-transformed pNGAL [log2(pNGAL)] 3.4, 95% confidence interval (CI) 2.24-5.15, P < .0001}. This association was substantially attenuated when eGFR was added to the model [sHR for log2(pNGAL) 1.63, 95% CI 0.92-2.88, P = .095]. Category-free net reclassification improvement of a risk model including log2(pNGAL) in addition to conventional risk factors and eGFR was 54.3% (95% CI 9.2%-99.3%) but C-statistic did not improve significantly.

CONCLUSIONS

pNGAL was an independent predictor of renal allograft loss in stable KTR from one transplant center but did not show consistent added value when compared with baseline predictors including the conventional marker eGFR. Future studies in larger cohorts are warranted.

Urinary neutrophil gelatinase-associated lipocalin (uNGAL) and kidney injury molecule-1 (uKIM-1) as markers of active lupus nephritis

BACKGROUND AND OBJECTIVES

Despite much research about lupus nephritis, none of the urinary biomarkers has been proven to be truly reflecting lupus nephritis activity, response to treatment, or prognosis. We aimed to study urinary biomarkers in lupus nephritis and test their relation to kidney damage.

PATIENTS AND METHODS

Forty patients with systemic lupus erythematosus (SLE) were divided into two graoups: (1) lupus nephritis group with biopsy-proven proliferative lupus nephritis (classes III and IV) and who did not receive immunosuppressive drugs within the preceding 3 months except for glucocorticoids and (2) lupus non-nephritis group with SLE patients without any renal manifestation. We assessed disease activity by the SLE disease activity index. uNGAL, uKim-1, uNGAL to urinary creatinine excretion (mg/dl), and uKim-1 to urinary creatinine excretion were measured in random spot urine samples at the time of renal biopsy and 6 months after the induction therapy.

RESULTS

The LN group before treatment showed higher levels of uNGAL and uKIM-1 (P-value < 0.001). ROC analysis showed that uNGAL at level of > 59 has a 95 % sensitivity, a 100 % specificity, and an AUC = 0.996 in the ability to diagnose LN. While the uKIM-1 ROC showed that at level of > 1.6, it has an 85 % sensitivity, an 80 % specificity, and an AUC = 0.919. uNGAL and uKIM levels were significantly lower after treatment (P-value < 0.001). No significant correlations were found between urinary markers before and after treatment with other clinical, inflammatory, and serological markers of lupus nephritis.

CONCLUSION

uNGAL, uKIM, uNGAL/Creat ratio, and uKIM/Creat ratio can be used as a predictor and a marker of disease activity for lupus nephritis. Key Points • Renal biopsy is the current standard for diagnosis of lupus nephritis and none of the urinary biomarkers has been fully concluded to have a diagnostic power to reflect the activity or the response to treatment. • However, based on the finding of the current study, uNGAL, uKIM, uNGAL/Creat ratio, and uKIM/Creat ratio showed significant diagnostic performance and were powerful indices of renal involvement in systemic lupus patients and as markers of disease activity.

Normothermic ex vivo perfusion of deceased donor kidneys and its clinical potential in kidney transplantation outcomes

In recent years, normothermic machine perfusion (NMP) has emerged in conversation surrounding organ preservation and transplantation techniques with the goal of improving patient and clinical outcomes. This is in great attempt to address the rate of non-utilization and the shortage of available organs in kidney transplantation. This focus in mind, normothermic perfusion presents itself as a potential tool to mimic physiological conditions and improve current preservation methods, such as static cold storage. This review serves to improve understanding of the observed connection between the consequences of ischemia and reperfusion injury and traditional preservation techniques as well as how renal NMP may mitigate these issues. Previous studies suggest that reducing time in static cold storage methods by promoting the normothermic perfusion model results in decreased delayed graft function and post-transplant complications. This review also aims to present the immense clinical potential NMP has on future kidney transplantation success and what this means for the fields of nephrology and transplantation. While great strides have been made to evaluate normothermic perfusion's impact on kidney graft viability and transplant success, future research into unified protocol, clinically relevant biomarkers, cost-utility analysis, and use with associated therapeutic and imaging modalities is paramount.

External Validation of a Urinary Biomarker Risk Score for the Prediction of Steroid Responsiveness in Adults With Nephrotic Syndrome

Introduction

In idiopathic nephrotic syndrome, response to corticosteroids remains the best indicator of prognosis. Noninvasive markers to predict a patient's response to steroids would allow improved prognostication and a more personalized approach to management. We have previously derived a urinary biomarker risk score which can differentiate steroid sensitive nephrotic syndrome (SSNS) from steroid resistant nephrotic syndrome (SRNS) in children. The goal of this study was to validate this previously derived biomarker risk score in a cohort of steroid-naïve adult patients, to determine whether the panel could be used to predict steroid responsiveness at the time of initial diagnosis.

Methods

In this external validation study, clinical data, and urinary specimens (obtained before initiation of steroid treatment) from adult patients were used in the Nephrotic Syndrome Study Network (NEPTUNE) cohort. A panel of 5 previously identified and validated urinary biomarkers, including neutrophil gelatinase-associated lipocalin (NGAL), vitamin D binding protein (VDBP), Fetuin-A (FetA), Transthyretin (TTR), and alpha-1 acid glycoprotein 2 (AGP2) was measured. A summary risk score for steroid resistance was calculated based on biomarker concentrations. Receiver operating characteristic curves were created for each log-transformed biomarker concentration and for the individual and combined biomarker risk score.

Results

The urine biomarker risk score predicted development of steroid resistance, with optimal sensitivity and specificity of 0.74, and area under the receiver operating characteristic curve (AUC) of 0.79 using both absolute and creatinine-corrected concentrations.

Conclusion

This study validates the previously derived urinary biomarker risk score to predict steroid resistance in adult patients with nephrotic syndrome at initial diagnosis.

Measurement of Neutrophil Gelatinase-Associated Lipocalin (Ngal) Following Neuroradiological Procedure/s in Patients with Aneurysmal Subarachnoid Hemorrhage: A Preliminary Study

Background

Radiocontrast administration during interventional neuroradiology (INR) procedures for aneurysmal subarachnoid haemorrhage (aSAH) can add to renal insult. Serum creatinine (sCr) is a conventional marker of acute kidney injury (AKI). Serum neutrophil gelatinase-associated lipocalin (sNGAL) is a novel marker which is increasingly used to predict renal injury in susceptible patients.

Objectives

The primary aim of this study was to evaluate correlation between serum neutrophil gelatinase-associated lipocalin (NGAL) and sCr in aSAH patients undergoing therapeutic or diagnostic INR procedures. The secondary aim was to find the incidence of contrast-induced AKI and hemodynamic complications during the study period.

Material and Methods

All consenting aSAH patients (18-60 years, Modified Hunt and Hess grade 1-4) posted for INR procedures during the study time were included. Patients with history of chronic renal disease, recent contrast exposure, or renal insufficiency were excluded. Blood samples for sCr and sNGAL were obtained preprocedure and then at 1, 6, 24, and 48 h after contrast administration. Hourly urine output was noted. AKI was defined by KDIGO guidelines.

Statistical Analysis Used

Repeated measurement analysis of variance, Posthoc Bonferroni test and Pearson correlation coefficient test.

Results

Fifty patients, mean age 47.34 ± 9.31 years, were enrolled for the study. Majority (48; 96%) were Hunt and Hess (H and H) grade I-III. The mean volume of contrast administered was 123.2 ± 53.08 mL. The mean sNGAL and sCr values at pre-op, 1, 6, 24, and 48 h were 124.99 ± 64.58, 148.40 ± 77.90, 147.33 ± 76.00, 125.49 ± 64.44, and 116.38 ± 61.79 ng/mL and 0.629 ± 0.23, 0.624 ± 0.22, 0.612 ± 0.21, 0.632 ± 0.19, and 0.577 ± 0.22 mg/dL, respectively. There was a correlation in sCr and sNGAL value (P < 0.001) at all study time points. However, no specific pattern was seen. No patient developed any AKI or hemodynamic complications in first 48 h.

Conclusions

There is a correlation between serum NGAL and sCr at individual time points. NGAL may represent a sensitive early biomarker of renal impairment after INR Procedures. There was no incidence of AKI after contrast administration in aSAH patients without predisposing renal risk factors.

Neutrophil gelatinase-associated lipocalin: a biochemical marker for acute kidney injury and long-term outcomes in patients presenting to the emergency department

Introduction

Creatinine has limitations in identifying and predicting acute kidney injury (AKI). Our study examined the utility of neutrophil gelatinase-associated lipocalin (NGAL) in predicting AKI in patients presenting to the emergency department (ED), and in predicting the need for renal replacement therapy (RRT), occurrence of major adverse cardiac events (MACE) and all-cause mortality at three months post visit.

Methods

This is a single-centre prospective cohort study conducted at Singapore General Hospital (SGH). Patients presenting to SGH ED from July 2011 to August 2012 were recruited. They were aged ≥21 years, with an estimated glomerular filtration rate <60 mL/min/1.73 m2, and had congestive cardiac failure, systemic inflammatory response syndrome or required hospital admission. AKI was diagnosed by researchers blinded to experimental measurements. Serum NGAL was measured as a point-of-care test.

Results

A total of 784 patients were enrolled, of whom 107 (13.6%) had AKI. Mean serum NGAL levels were raised (P < 0.001) in patients with AKI (670.0 ± 431.9 ng/dL) compared with patients without AKI (490.3 ± 391.6 ng/dL). The sensitivity and specificity of NGAL levels >490 ng/dL for AKI were 59% (95% confidence interval [CI] 49%-68%) and 65% (95% CI 61%-68%), respectively. Need for RRT increased 21% per 100 ng/dL increase in NGAL (P < 0.001), whereas odds of death in three months increased 10% per 100 ng/dL increase in NGAL (P = 0.028). No clear relationship was observed between NGAL levels and MACE.

Conclusion

Serum NGAL identifies AKI and predicts three-month mortality.

Contemporary Biomarkers for Renal Transplantation: A Narrative Overview

Renal transplantation (RT) is the preferred treatment for end-stage renal disease. However, clinical challenges persist, i.e., early detection of graft dysfunction, timely identification of rejection episodes, personalization of immunosuppressive therapy, and prediction of long-term graft survival. Biomarkers have emerged as valuable tools to address these challenges and revolutionize RT patient care. Our review synthesizes the existing scientific literature to highlight promising biomarkers, their biological characteristics, and their potential roles in enhancing clinical decision-making and patient outcomes. Emerging non-invasive biomarkers seemingly provide valuable insights into the immunopathology of nephron injury and allograft rejection. Moreover, we analyzed biomarkers with intra-nephron specificities, i.e., glomerular vs. tubular (proximal vs. distal), which can localize an injury in different nephron areas. Additionally, this paper provides a comprehensive analysis of the potential clinical applications of biomarkers in the prediction, detection, differential diagnosis and assessment of post-RT non-surgical allograft complications. Lastly, we focus on the pursuit of immune tolerance biomarkers, which aims to reclassify transplant recipients based on immune risk thresholds, guide personalized immunosuppression strategies, and ultimately identify patients for whom immunosuppression may safely be reduced. Further research, validation, standardization, and prospective studies are necessary to fully harness the clinical utility of RT biomarkers and guide the development of targeted therapies.

Recent Advances in Urinary Peptide and Proteomic Biomarkers in Chronic Kidney Disease: A Systematic Review

Biomarker development, improvement, and clinical implementation in the context of kidney disease have been a central focus of biomedical research for decades. To this point, only serum creatinine and urinary albumin excretion are well-accepted biomarkers in kidney disease. With their known blind spot in the early stages of kidney impairment and their diagnostic limitations, there is a need for better and more specific biomarkers. With the rise in large-scale analyses of the thousands of peptides in serum or urine samples using mass spectrometry techniques, hopes for biomarker development are high. Advances in proteomic research have led to the discovery of an increasing amount of potential proteomic biomarkers and the identification of candidate biomarkers for clinical implementation in the context of kidney disease management. In this review that strictly follows the PRISMA guidelines, we focus on urinary peptide and especially peptidomic biomarkers emerging from recent research and underline the role of those with the highest potential for clinical implementation. The Web of Science database (all databases) was searched on 17 October 2022, using the search terms "marker *" OR biomarker * AND "renal disease" OR "kidney disease" AND "proteome *" OR "peptid *" AND "urin *". English, full-text, original articles on humans published within the last 5 years were included, which had been cited at least five times per year. Studies based on animal models, renal transplant studies, metabolite studies, studies on miRNA, and studies on exosomal vesicles were excluded, focusing on urinary peptide biomarkers. The described search led to the identification of 3668 articles and the application of inclusion and exclusion criteria, as well as abstract and consecutive full-text analyses of three independent authors to reach a final number of 62 studies for this manuscript. The 62 manuscripts encompassed eight established single peptide biomarkers and several proteomic classifiers, including CKD273 and IgAN237. This review provides a summary of the recent evidence on single peptide urinary biomarkers in CKD, while emphasizing the increasing role of proteomic biomarker research with new research on established and new proteomic biomarkers. Lessons learned from the last 5 years in this review might encourage future studies, hopefully resulting in the routine clinical applicability of new biomarkers.

NGAL as Biomarker of Clinical and Subclinical Damage of Kidney Function after Coronary Angiography

Contrast-induced acute kidney injury (CI-AKI) is a serious complication after angiographic examinations in cardiology. Diagnosis may be delayed based on standard serum creatinine, and subclinical forms of kidney damage may not be detected at all. In our study, we investigate the clinical use in these directions of a “damage”-type biomarker—neutrophil gelatinase-associated lipocalin (NGAL). Among patients with a high-risk profile undergoing scheduled coronary angiography and/or angioplasty, plasma NGAL was determined at baseline and at 4th and 24th h after contrast administration. In the CI-AKI group, NGAL increased significantly at the 4th hour (Me 109.3 (IQR 92.1–148.7) ng/mL versus 97.6 (IQR 69.4–127.0) ng/mL, p = 0.006) and at the 24th hour (Me 131.0 (IQR 81.1–240.8) ng/mL, p = 0.008). In patients with subclinical CI-AKI, NGAL also increased significantly at the 4th hour (Me 94.0 (IQR 75.5–148.2) ng/mL, p = 0.002) and reached levels close to those in patients with CI-AKI. Unlike the new biomarker, however, serum creatinine did not change significantly in this group. The diagnostic power of NGAL is extremely good—AUC 0.847 (95% CI: 0.677–1.000; p = 0.001) in CI-AKI and AUC 0.731 (95% CI: 0.539–0.924; p = 0.024) in subclinical CI-AKI. NGAL may be a reliable biomarker for the early diagnosis of clinical and subclinical forms of renal injury after contrast angiographic studies.

Follistatin-like 1 and Biomarkers of Neutrophil Activation Are Associated with Poor Short-Term Outcome after Lung Transplantation on VA-ECMO

The investigation of biomarkers associated with undesired outcome following lung transplantation (LuTX) is essential for a better understanding of the underlying pathophysiology, an earlier identification of susceptible recipients and the development of targeted therapeutic options. We therefore determined the longitudinal perioperative course of putative cytokines related to neutrophil activation (chemokine CC motif ligand 4 (CCL-4), interleukin (IL)-23 and Lipocalin 2 (LCN2)) and a cytokine that has been implicated in graft-versus-host disease (Follistatin-like 1 (FSTL1)) in 42 consecutive patients undergoing LuTX. We plotted receiver-operating curves (ROC) to assess the predictive power of the measured cytokines for short-term outcomes namely primary graft dysfunction (PGD), early complications requiring extracorporeal membrane oxygenation (ECMO), and a high postoperative sequential organ failure assessment (SOFA). All cytokines increased immediately after surgery. ROC analyses determined significant associations between CCL4 and a high SOFA score (area under the curve (AUC) 0.74 (95%CI:0.5−0.9; p < 0.05), between LCN2 and postoperative ECMO support (AUC 0.73 (95%CI:0.5−0.9; p < 0.05), and between FSTL1 and PGD (AUC 0.70 (95%CI:0.5−0.9; p < 0.05). The serum concentrations of the neutrophil-derived cytokines LCN2 and CCL4 as well as FSTL1 were all related to poor outcome after LuTX. The specific predictive power, however, still has to be assessed in larger trials. The potential role of FSTL1 as a biomarker in the development of PGD could be of great interest particularly since this protein appears to play a crucial role in allograft tolerance.

In-silico analysis of interacting pathways through KIM-1 protein interaction in diabetic nephropathy

Background

Human Kidney Injury Molecule-1, also known as HAVCR-1 (Hepatitis A virus cellular receptor 1), belongs to the cell-surface protein of immunoglobulin superfamily involved in the phagocytosis by acting as scavenger receptor epithelial cells. The study focused on pinpointing the mechanisms and genes that interact with KIM-1.

Methods

This in-silico study was done from March 2019 to December 2019. The Enrichment and protein-protein interaction (PPI) network carefully choose proteins. In addition, the diagramed gene data sets were accomplished using FunRich version 3.1.3. It was done to unveil the proteins that may affect the regulation of HAVCR1 or may be regulated by this protein. These genes were then further considered in pathway analysis to discover the dysregulated pathways in diabetic nephropathy. The long list of differentially expressed genes is meaningless without pathway analysis.

Results

Critical pathways that are dysregulated in diabetic nephropathy patients have been identified. These include Immune System (Total = 237, P < 0.05), Innate Immune System (Total = 140, P < 0.05), Cytokine Signaling Immune system (Total = 116, P < 0.05), Adaptive Immune System (Total = 85) and Neutrophil degranulation (Total = 78).

Conclusion

The top 5 genes that are interacting directly with HIVCR1 include CASP3, CCL2, SPP1, B2M, and TIMP1 with degrees 161, 144, 108, 107, and 105 respectively for Immune system pathways (Innate Immune System, Cytokine Signaling Immune system, Adaptive Immune System and Neutrophil degranulation).

Overview of Diagnostic Criteria and Epidemiology of Acute Kidney Injury and Acute Kidney Disease in the Critically Ill Patient

Since the description ischuria renalis by William Heberden (1), AKI has remained a prominent complication of critical illness. Beyond KRT, treatment has been limited by the capacity to phenotype this condition. Here, we chronicle the evolution of attempts to classify AKI, including the adoption of consensus definitions, the expansion of diagnosis and prognosis with novel biomarkers, and emerging tools such as artificial intelligence (AI).

A Novel Soluble ACE2 Protein Provides Lung and Kidney Protection in Mice Susceptible to Lethal SARS-CoV-2 Infection

Background: Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) uses full-length angiotensin converting enzyme 2 (ACE2) as a main receptor to enter target cells. The goal of this study was to demonstrate the preclinical efficacy of a novel soluble ACE2 protein with increased duration of action and binding capacity in a lethal mouse model of COVID-19. Methods: A human soluble ACE2 variant fused with an albumin binding domain (ABD) was linked via a dimerization motif hinge-like 4-cysteine dodecapeptide (DDC) to improve binding capacity to SARS-CoV-2. This novel soluble ACE2 protein (ACE2 1-618-DDC-ABD) was then administered intranasally and intraperitoneally to mice prior to intranasal inoculation of SARS-CoV-2 and then for two additional days post viral inoculation. Results: Untreated animals became severely ill and all had to be humanely euthanized by day 6/7 and had pulmonary alveolar hemorrhage with mononuclear infiltrates. In contrast, all but one mouse infected with a lethal dose of SARS-CoV-2 that received ACE2-1-618-DDC-ABD survived. In the animals inoculated with SARS-CoV-2 that were untreated, viral titers were high in the lungs and brain but virus was absent in the kidneys. However, some untreated animals had variable degrees of kidney proximal tubular injury with increased NGAL and TUNEL staining indicating attenuation of the proximal tubular brush border. In contrast, viral titers in the lung and brain were reduced or non-detectable in mice that received ACE2 1-618 DDCABD, and the animals developed only moderate disease as assessed by a near-normal clinical score, minimal weight loss, and improved lung and kidney injury Conclusions: This study demonstrates the preclinical efficacy of a novel soluble ACE2 protein, termed ACE2 1- 618-DDC-ABD, in a lethal mouse model of SARS-CoV-2 infection that causes severe lung injury as well as variable degrees of moderate proximal tubular injury.

Neutrophil gelatinase–associated lipocalin as a marker for contrast-induced nephropathy in patients undergoing percutaneous coronary intervention: A prospective observational analysis

Introduction:

Incidence of contrast-induced nephropathy (CIN) post percutaneous coronary intervention (PCI) varies between 5% and 20%. Neutrophil gelatinase–associated lipocalin (NGAL) is a sensitive marker for acute kidney injury. Data regarding the predictive accuracy of NGAL in Indian patients undergoing PCI is sparse.

Methods:

A total of 212 consecutive “all-comer” patients, undergoing PCI from March 2015 to April 2016 were recruited in this single-center observational study. Plasma NGAL levels were measured at 4 hours post PCI using commercially available enzyme-linked immunosorbent assay (Triage® Alere™, San Diego, CA, USA).

Results:

Twenty-five (11.8%) patients developed CIN. The 4-hour post-PCI plasma NGAL levels were significantly higher in patients with CIN than without (400.6 ± 269.3 ng/mL vs. 109.8 ± 68.0 ng/mL, P < 0.0001). Patients developing CIN had higher age, low estimated glomerular filtration rate (eGFR), and higher contrast volume usage during PCI. After adjusting for confounding factors, diabetes mellitus (adjusted odds ratio [AOR] 3.04; P = 0.039; 95% confidence interval [CI]: 1.06–8.73), hypotension at presentation (AOR 24.84; P < 0.0001; 95% CI: 4.65–132.83), and multi-staged PCI (AOR 13.45; P < 0.0001; 95% CI: 4.54–39.79) were found to independently predict the development of CIN. NGAL levels significantly correlated with age (r = 0.149, P = 0.031), eGFR (r = −0.385, P < 0.0001), hemoglobin (r = −0.214, P = 0.002), contrast volume (r = 0.185, P = 0.007), and 48-hour post-PCI serum creatinine levels (r = 0.334, P < 0.0001). At a cutoff of 256.5 ng/mL, plasma NGAL had a sensitivity of 68% and a specificity of 95.2% (area under the curve = 0.878; P < 0.0001; 95% CI: 0.801–0.955) to predict the occurrence of CIN.

Conclusions:

Plasma NGAL is an early and highly predictive biomarker of CIN in patients undergoing PCI. Patients having diabetes, hypotension at presentation and those undergoing second-stage procedures are at a high risk of developing CIN after PCI.

Urinary Proteomics in Kidney Transplantation

Although kidney transplantation is the best treatment option for end stage kidney disease, it is still associated with long-term graft failure. One of the greater challenges for transplant professionals is the ability to identify grafts with a high risk of failure before initial decline of eGFR with irreversible graft changes. Transplantation medicine is facing an emerging need for novel disease end point-specific biomarkers, with practical application in preventive screening, early diagnostic, and improved prognostic and therapeutic utility. The aim of our review was to evaluate the clinical application of urinary proteomics in kidney transplant recipients at risk for any type of future graft failure.

Neutrophil gelatinase-associated lipocalin does not originate from the kidney during reperfusion in clinical renal transplantation

Background

Acute Kidney Injury (AKI) is a common clinical complication. Plasma/serum neutrophil gelatinase-associated lipocalin (NGAL) has been proposed as a rapid marker of AKI. However, NGAL is not kidney-specific. It exists in three isoforms (monomeric, homo-dimeric and hetero-dimeric). Only the monomeric isoform is produced by renal tubular cells and plasma NGAL levels are confounded by the release of all NGAL isoforms from neutrophils. Our aim was to investigate whether NGAL is released into blood from injured renal tubules.

Methods

Kidney transplantation (n = 28) served as a clinical model of renal ischaemic injury. We used ELISA to measure NGAL concentrations at 2 minutes after kidney graft reperfusion in simultaneously taken samples of renal arterial and renal venous blood. Trans-renal gradients (venous–arterial) of NGAL were calculated. We performed Western blotting to distinguish between renal and non-renal NGAL isoforms. Liver-type fatty acid binding protein (LFABP) and heart-type fatty acid binding protein (HFABP) served as positive controls of proximal and distal tubular damage.

Results

Significant renal release of LFABP [trans-renal gradient 8.4 (1.7–30.0) ng/ml, p = 0.005] and HFABP [trans-renal gradient 3.7 (1.1–5.0) ng/ml, p = 0.003] at 2 minutes after renal graft reperfusion indicated proximal and distal tubular damage. NGAL concentrations were comparable in renal venous and renal arterial blood. Thus, there was no trans-renal gradient of NGAL. Western blotting revealed that the renal NGAL isoform represented only 6% of the total NGAL in renal venous blood.

Conclusions

Ischaemic proximal and distal tubular damage occurs in kidney transplantation without concomitant NGAL washout from the kidney graft into blood. Plasma/serum NGAL levels are confounded by the release of NGAL from neutrophils. Present results do not support the interpretation that increase in plasma NGAL is caused by release from the renal tubules.

Intravenous Laser Therapy in Patients With Acute Kidney Injury: A Randomized Clinical Trial

Introduction: Although intravascular laser irradiation of blood (ILIB) is deemed an innocuous and useful technique for laser therapy, particularly when systemic effects are required, no study, to our knowledge, has been conducted on the effectiveness and innocuousness of ILIB in treating acute kidney injury (AKI). Objective: This study aimed to assess the feasibility and outcomes of ILIB in the management of patients with AKI and comparing them with the Sham-laser group. Materials and Methods: Twenty-six patients with intra-renal AKI (24-95 years old) at Tajrish Hospitals were evaluated for enrollment eligibility in this clinical trial study. This study was conducted at the nephrology department of Shahid Beheshti University of Medical Science, Tehran, Iran, between 2018 and 2019. Based on the treatment method, the patients' assignment to two groups (ILIB or Sham-laser) was randomly done. Demographic characteristics, need for dialysis, hemoglobin and serum biochemistry changes, serum and urine neutrophil gelatinase-associated lipocalin (NGAL) changes, laser complications, and the hospitalization period were recorded. Results: In terms of the baseline characteristics and biochemistry serum level, no differences were seen between the two groups. All post-treatment parameters, except the hemoglobin value, significantly improved in both groups. Urine NGAL and serum NGAL show declines from the baseline in both groups; however, the reduction slope of these parameters occurred faster in the laser group in a statistically significant manner. Conclusion: A decline in NGAL levels in the laser group during the treatment may suggest that the ILIB can help patients with AKI recover better.

Serial urinary neutrophil gelatinase associated lipocalin in pediatric diabetic ketoacidosis with acute kidney injury

BACKGROUND

Acute kidney injury (AKI) due to Diabetic Ketoacidosis (DKA) is rather common. Novel biomarkers to diagnose AKI are being increasingly used in different settings. The use of urinary Neutrophil Gelatinase-Associated Lipocalin (uNGAL) in predicting persistent AKI in pediatric DKA cases is still not thoroughly investigated.

METHODS

This was a secondary analysis of Saline versus Plasma-Lyte in Ketoacidosis (SPinK) trial data; 66 children (> 1 month-12 years) with DKA, defined by the International Society for Pediatric and Adolescent Diabetes (ISPAD), were analyzed. Children with cerebral edema, chronic kidney disease and those who received pre-referral fluids and/or insulin were excluded. uNGAL and urine NGAL-creatinine ratio (uNCR) at 0 and 24 h were measured in all. Persistent AKI was defined as a composite outcome of continuance of AKI defined by the Kidney Disease Improving Global Outcomes (KDIGO) stage 2 or 3 beyond 48 h from AKI onset, progression of AKI from either KDIGO stage 0 or 1 to a worse stage, need of renal replacement therapy or death.

MAIN OUTCOMES

Thirty-five (53%) children had AKI at admission; 32 (91.4%) resolved within 48 h. uNGAL was significantly higher in the AKI group at admission [79.8 ± 27.2 vs 54.6 ± 22.0, p = 0.0002] and at 24 h [61.4 ± 28.3 vs 20.2 ± 14.5, p = 0.0003]. Similar trend was observed with uNCR at admission [6.7 ± 3.7 vs 4.1 ± 2.6, p = 0.002] and at 24 h [6.3 ± 2.5 vs 1.2 ± 1.0, p = 0.01]. Furthermore, uNGAL at admission showed a moderate positive linear correlation with serum creatinine. Additionally, elevated uNGAL at 0 and 24 h correlated with corresponding KDIGO stages. Admission uNGAL >88 ng/ml and uNCR of >11.3 ng/mg had a sensitivity of 66% and 67%, specificity of 76% and 95%, and Area under the receiver operating characteristic curve (AUC) of 0.78 and 0.89 respectively for predicting persistent AKI at 48 h.

CONCLUSIONS

Majority of AKI resolved with fluid therapy. While uNGAL and uNCR both correlated with serum creatinine and AKI stages, serial uNCR was a better predictor of persistent AKI than uNGAL alone. However, feasibility of routine uNGAL measurement to predict persistent AKI in DKA needs further elucidation.

TRIAL REGISTRATION

This was a secondary analysis of the data of SPinK trial [CTRI/2018/05/014042 ( ctri.nic.in )].

Biomarkers as diagnostic tests for delayed graft function in kidney transplantation

Delayed graft function (DGF) after kidney transplantation is associated with inferior outcomes and higher healthcare costs. DGF is currently defined as the requirement for dialysis within seven days post-transplant; however, this definition is subjective and nonspecific. Novel biomarkers have potential to improve objectivity and enable earlier diagnosis of DGF. We reviewed the literature to describe the range of novel biomarkers previously studied to predict DGF. We identified marked heterogeneity and low reporting quality of published studies. Among the novel biomarkers, serum NGAL had the greatest potential as a biomarker to predict DGF, but requires further assessment and validation through larger scale studies of diagnostic test performance. Given inadequacies in the dialysis-based definition, coupled with the high incidence and impact of DGF, such studies should be pursued.

Lipocalin 2 increases after high-intensity exercise in humans and influences muscle gene expression and differentiation in mice

Lipocalin 2 (LCN2) is an adipokine that accomplishes several functions in diverse organs. However, its importance in muscle and physical exercise is currently unknown. We observed that following acute high‐intensity exercise (“Gran Sasso d'Italia” vertical run), LCN2 serum levels were increased. The Wnt pathway antagonist, DKK1, was also increased after the run, positively correlating with LCN2, and the same was found for the cytokine Interleukin 6. We, therefore, investigated the involvement of LCN2 in muscle physiology employing an Lcn2 global knockout (Lcn2^−/−) mouse model. Lcn2^−/− mice presented with smaller muscle fibres but normal muscle performance (grip strength metre) and muscle weight. At variance with wild type (WT) mice, the inflammatory cytokine Interleukin 6 was undetectable in Lcn2^−/− mice at all ages. Intriguingly, Lcn2^−/− mice did not lose gastrocnemius and quadriceps muscle mass and muscle performance following hindlimb suspension, while at variance with WT, they lose soleus muscle mass. In vitro, LCN2 treatment reduced the myogenic differentiation of C2C12 and primary mouse myoblasts and influenced their gene expression. Treating myoblasts with LCN2 reduced myogenesis, suggesting that LCN2 may negatively affect muscle physiology when upregulated following high‐intensity exercise.

Restoration of afferent arteriolar autoregulatory behavior in ischemia-reperfusion injury in rat kidneys

Renal autoregulation is critical in maintaining stable renal blood flow (RBF) and glomerular filtration rate (GFR). Renal ischemia-reperfusion (IR)-induced kidney injury is characterized by reduced RBF and GFR. The mechanisms contributing to renal microvascular dysfunction in IR have not been fully determined. We hypothesized that increased reactive oxygen species (ROS) contributed to impaired renal autoregulatory capability in IR rats. Afferent arteriolar autoregulatory behavior was assessed using the blood-perfused juxtamedullary nephron preparation. IR was induced by 60 min of bilateral renal artery occlusion followed by 24 h of reperfusion. Afferent arterioles from sham rats exhibited normal autoregulatory behavior. Stepwise increases in perfusion pressure caused pressure-dependent vasoconstriction to 65 ± 3% of baseline diameter (13.2 ± 0.4 μm) at 170 mmHg. In contrast, pressure-mediated vasoconstriction was markedly attenuated in IR rats. Baseline diameter averaged 11.7 ± 0.5 µm and remained between 90% and 101% of baseline over 65-170 mmHg, indicating impaired autoregulatory function. Acute antioxidant administration (tempol or apocynin) to IR kidneys for 20 min increased baseline diameter and improved autoregulatory capability, such that the pressure-diameter profiles were indistinguishable from those of sham kidneys. Furthermore, the addition of polyethylene glycol superoxide dismutase or polyethylene glycol-catalase to the perfusate blood also restored afferent arteriolar autoregulatory responsiveness in IR rats, indicating the involvement of superoxide and/or hydrogen peroxide. IR elevated mRNA expression of NADPH oxidase subunits and monocyte chemoattractant protein-1 in renal tissue homogenates, and this was prevented by tempol pretreatment. These results suggest that ROS accumulation, likely involving superoxide and/or hydrogen peroxide, impairs renal autoregulation in IR rats in a reversible fashion.NEW & NOTEWORTHY Renal ischemia-reperfusion (IR) leads to renal microvascular dysfunction manifested by impaired afferent arteriolar autoregulatory efficiency. Acute administration of scavengers of reactive oxygen species, polyethylene glycol-superoxide dismutase, or polyethylene glycol-catalase following renal IR restored afferent arteriolar autoregulatory capability in IR rats, indicating that renal IR led to reversible impairment of afferent arteriolar autoregulatory capability. Intervention with antioxidant treatment following IR may improve outcomes in patients by preserving renovascular autoregulatory function and potentially preventing the progression to chronic kidney disease after acute kidney injury.

Inhibition of BRD4 Reduces Neutrophil Activation and Adhesion to the Vascular Endothelium Following Ischemia Reperfusion Injury

Renal ischemia reperfusion injury (IRI) is associated with inflammation, including neutrophil infiltration that exacerbates the initial ischemic insult. The molecular pathways involved are poorly characterized and there is currently no treatment. We performed an in silico analysis demonstrating changes in NFκB-mediated gene expression in early renal IRI. We then evaluated NFκB-blockade with a BRD4 inhibitor on neutrophil adhesion to endothelial cells in vitro, and tested BRD4 inhibition in an in vivo IRI model. BRD4 inhibition attenuated neutrophil adhesion to activated endothelial cells. In vivo, IRI led to increased expression of cytokines and adhesion molecules at 6 h post-IRI with sustained up-regulated expression to 48 h post-IRI. These effects were attenuated, in part, with BRD4 inhibition. Absolute neutrophil counts increased significantly in the bone marrow, blood, and kidney 24 h post-IRI. Activated neutrophils increased in the blood and kidney at 6 h post-IRI and remained elevated in the kidney until 48 h post-IRI. BRD4 inhibition reduced both total and activated neutrophil counts in the kidney. IRI-induced tubular injury correlated with neutrophil accumulation and was reduced by BRD4 inhibition. In summary, BRD4 inhibition has important systemic and renal effects on neutrophils, and these effects are associated with reduced renal injury.

The mRNA landscape profiling reveals potential biomarkers associated with acute kidney injury AKI after kidney transplantation

Background

This study aims to identify potential biomarkers associated with acute kidney injury (AKI) post kidney transplantation.

Material and Methods

Two mRNA expression profiles from Gene Expression Omnibus repertory were downloaded, including 20 delayed graft function (DGF) and 68 immediate graft function (IGF) samples. Differentially expressed genes (DEGs) were identified between DGF and IGF group. The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis of DEGs were performed. Then, a protein-protein interaction analysis was performed to extract hub genes. The key genes were searched by literature retrieval and cross-validated based on the training dataset. An external dataset was used to validate the expression levels of key genes. Receiver operating characteristic curve analyses were performed to evaluate diagnostic performance of key genes for AKI.

Results

A total of 330 DEGs were identified between DGF and IGF samples, including 179 up-regulated and 151 down-regulated genes. Of these, OLIG3, EBF3 and ETV1 were transcription factor genes. Moreover, LEP, EIF4A3, WDR3, MC4R, PPP2CB, DDX21 and GPT served as hub genes in PPI network. EBF3 was significantly up-regulated in validation GSE139061 dataset, which was consistently with our initial gene differential expression analysis. Finally, we found that LEP had a great diagnostic value for AKI (AUC = 0.740).

Conclusion

EBF3 may be associated with the development of AKI following kidney transplantation. Furthermore, LEP had a good diagnostic value for AKI. These findings provide deeper insights into the diagnosis and management of AKI post renal transplantation.

Value of Urinary Neutrophil Gelatinase-Associated Lipocalin versus Conventional Biomarkers in Predicting Response to Treatment of Active Lupus Nephritis

Introduction

Lupus nephritis (LN) affects almost two-thirds of systemic lupus erythematosus (SLE) patients. Despite initial aggressive therapy, up to 25% of patients with LN will progress to permanent renal damage. Conventional serum markers for LN lack the sensitivity of an ideal biomarker. Urinary neutrophil gelatinase-associated lipocalin (UNGAL) is an excellent biomarker for early diagnosis of acute kidney injury and predicting renal outcomes.

Objective

To measure UNGAL among LN patients to correlate its levels with renal disease activity and to investigate its predictive performance in response to induction therapy. Patients and Methods. 40 SLE patients with biopsy-proven LN class III, IV, or V were randomly selected. The study was conducted in the internal medicine department and outpatient clinic in Ain Shams University Hospitals and completed after six months. UNGAL was measured at baseline, three-month follow-up, and after complete induction therapy.

Results

In LN patients at baseline, the mean serum creatinine was 2.57 ± 0.96 mg/dL and the mean UNGAL was 33.50 ± 18.34 ng/dL. Mean UNGAL levels of complete response, partial response, and nonresponse groups were 14.48 ± 2.99 ng/mL, 34.49 ± 4.09 ng/mL, and 62.07 ± 14.44 ng/mL, respectively. Based on the ROC curve, we found a better performance of baseline UNGAL to discriminate the complete response group from partial and nonresponse groups to predict response to induction, outperforming conventional biomarkers. The area under the curve was 0.943, and the best cutoff level was 26.5 ng/mL (92.31% sensitivity and 88.89% specificity).

Conclusion

UNGAL performed better than conventional biomarkers in predicting response to treatment of active LN.

Evaluation of renal injury in children with uncorrected CHDs with significant shunt using urinary neutrophil gelatinase-associated lipocalin

BACKGROUND

CHDs can be complicated by renal injury which worsens morbidity and mortality. Urinary neutrophil gelatinase-associated lipocalin, a sensitive and specific biomarker of renal tubular injury, has not been studied in children with uncorrected CHDs. This study evaluated renal injury in children with uncorrected CHDs using this biomarker.

METHODS

The patients were children with uncorrected CHDs with significant shunt confirmed on echocardiogram with normal renal ultrasound scan, in the paediatric cardiology clinic of a tertiary hospital. The controls were age-matched healthy children recruited from general practice clinics. Information on bio-data and socio-demographics were collected and urine was obtained for measurement of urinary neutrophil gelatinase-associated lipocalin levels.

RESULTS

A total of 65 children with uncorrected CHDs aged 2 to 204 months were recruited. Thirty-one (47.7%) were males while 36 (55.4%) had acyanotic CHDs. The median urinary neutrophil gelatinase-associated lipocalin level of patients of 26.10 ng/ml was significantly higher than controls of 16.90 ng/ml (U = 1624.50, p = 0.023). The median urinary neutrophil gelatinase-associated lipocalin level of patients with cyanotic and acyanotic CHDs were 30.2 ng/ml and 22.60 ng/ml respectively; (Mann-Whitney U = 368.50, p = 0.116). The prevalence of renal injury using 95th percentile cut-off value of urinary neutrophil gelatinase-associated lipocalin was 16.9%. Median age of patients with renalinjury was 16 (4-44) months.

CONCLUSIONS

Children with uncorrected CHDs have renal injury detected as early as infancy. The use of urinary neutrophil gelatinase-associated lipocalin in early detection of renal injury in these children may enhance early intervention and resultant prevention of morbidity and reduction in mortality.

Donor Plasma Mitochondrial DNA Is Correlated with Posttransplant Renal Allograft Function

BACKGROUND

The lack of accurate biomarkers makes it difficult to determine whether organs are suitable for transplantation. Mitochondrial DNA (mtDNA) correlates with tissue damage and kidney disease, making it a potential biomarker in organ evaluation.

METHODS

Donors who had experienced cardiac death and successfully donated their kidneys between January 2015 and May 2017 were included this study. We detected the level of mtDNA in the plasma of the donor using quantitative real-time polymerase chain reaction and then statistically analyzed the relationship between the level of mtDNA and the delayed graft function (DGF) of the recipient.

RESULTS

The incidence of DGF or slowed graft function (SGF) increased by 4 times (68% versus 16%, P < 0.001) when the donor mtDNA (dmtDNA) level was >0.114. When dmtDNA levels were >0.243, DGF and primary nonfunction were approximately 100% and 44%, respectively. Moreover, dmtDNA was an independent risk factor for slowed graft function and DGF. A prediction model for DGF based on dmtDNA achieved an area under the receiver operating characteristic curve for a prediction score as high as 0.930 (95% confidence interval 0.856-1.000), and the validation cohort results showed that the sensitivity and specificity of the model were 100% and 78%, respectively. dmtDNA levels were correlated with 6-month allograft function (R=0.332, P < 0.001) and 1-year graft survival (79% versus 99%, P < 0.001).

CONCLUSIONS

We conclusively demonstrated that plasma dmtDNA was an independent risk factor for DGF, which is valuable in organ evaluation. dmtDNA is a possible first predictive marker for primary nonfunction and worth further evaluation.

An electrochemical sandwich-type aptasensor for determination of lipocalin-2 based on graphene oxide/polymer composite and gold nanoparticles

In this work, we reported an electrochemical aptasensor based on the poly-3-amino-1,2,4-triazole-5-thiol/graphene oxide composite (P(ATT)-GO) and gold nanoparticles (AuNPs) modified graphite screen-printed electrode (GSPE) (GSPE/P(ATT)-GO/AuNPs) for determination of lipocalin-2 (LCN2) (neutrophil gelatinase-associated lipocalin). A sandwich based strategy was utilized to enhance the electrochemical signal. First, a thiol tethered DNA aptamer was immobilized onto the composite electrode. Then, the LCN2 solution was incubated with the aptamer modified GSPE/P(ATT)-GO/AuNPs. Secondary aptamer (Apt2) peculiar to the LCN2 and labeled with biotin was interacted with the LCN2. A streptavidin-alkaline phosphatase conjugate was then applied to the surface. The determination of LCN2 was performed by using the electroactive property of α-naphthol which is acquired the product from the interaction between alkaline phosphatase and α-naphthyl phosphate. The constructed electrode was characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The aptamer modified GSPE/P(ATT)-GO/AuNPs showed the superior electrocatalytic performance towards the voltammetric determination of LCN2 with a wide linear range (1.0-1000.0 ng/mL) and a low limit of detection (LOD) (0.3 ng/mL). The proposed aptasensor revealed the excellent sensitivity, anti-interference ability and reproducibility which approved that the GSPE/P (ATT)-GO/AuNPs is a promising composite for the sensitive detection of LCN2. The fabricated aptasensor was applied for the determination of LCN2 in fetal bovine serum samples using the standard addition method and the recovery values were in the range of 99.2% and 103.22%.

Effect of goal-directed therapy on post-operative neutrophil gelatinase-associated lipocalin profile in patients undergoing on-pump coronary artery surgery

Purpose

Neutrophil gelatinase-associated lipocalin (NGAL) is an early biomarker of acute kidney injury (AKI). Goal-directed therapy (GDT) in on-pump coronary artery bypass grafting (CABG) has been associated with lower post-operative NGAL levels in recent studies. The present study aimed at comparing plasma (P) and urinary (U)-NGAL levels following the use of GDT versus conventional haemodynamic therapy (CT) in patients undergoing on-pump CABG.

Methods

A prospective randomised controlled study conducted in a single university hospital. A total of 54 patients in the GDT group and 56 patients in CT group after exclusions.

Results

U-NGAL was significantly lower immediately post-surgery (T ₁) in GDT group (25.11 ± 1.5 versus 27.80 ± 1.7 μg/L; p < 0.001) and at 4 h (T ₂) (38.19 ± 23.6 versus 52.30 ± 28.3 μg/L; p = 0.006) and at 24 h post-operatively (T ₃) (34.85 ± 14 versus 39.7 ± 11.1 μg/L; p = 0.047). P-NGAL was comparable between groups at T ₁ but lower in the GDT group at T ₂ (92.81 ± 4.8 versus 94.77 ± 4.5 μg/L; p = 0.03) and T ₃ (67.44 ± 3.7 versus 75.96 ± 5.3 μg/L; p < 0.001). U-NGAL levels correlated well with the peak post-operative creatinine as compared to P-NGAL. On-pump patients manifest neutrophil activation, accounting for comparable levels of P-NGAL in the two groups at T ₁. GDT-based haemodynamic management resulted in lower U-NGAL levels at T ₁, T ₂ and T ₃ and lower P-NGAL levels at T ₂ and T ₃.

Conclusions

Haemodynamic optimisation with GDT prevents further renal insult initiated with the inflammatory activation with cardiopulmonary bypass (CPB), as evidenced by lower post-operative U-NGAL levels.

Evaluation of kidney injury molecule-1 as a disease progression biomarker in diabetic nephropathy

Background & Objective:

Kidney Injury Molecule-1 (KIM-1) is a peptide whose release into circulation is specific to tubular injury. This study aimed to estimate levels of kidney injury molecule-1 in diabetic patients with and without kidney disease. And evaluate the role of KIM-1 as an early screening marker of progressive kidney injury.

Methods:

This follow-up study included n=85 subjects from the diabetic clinic of Jinnah Post Graduate Medical Center (JPMC) in collaboration with Aga Khan University from November 2016 till September 2017. They were divided as: i) Group A1 (n=30) participants with diabetes for <5 years without microalbuminuria ii) Group A2 (n= 30) subjects with diabetes for 6-10 years with microalbuminuria; iii) Group B (n=25) subjects as healthy control group. All study participants were followed for 6 months and their blood glucose, urea, creatinine, electrolytes, albuminuria and serum KIM-1 were assayed.

Results:

High KIM-1 at baseline was present in group A2 patients as compared to controls and group A1 (p<0.001). Higher levels were seen after six months in group A1 along with the presence of micro albuminuria (p<0.001) suggesting kidney damage. Moderate positive association were seen for KIM1 with creatinine levels (r=0.530; p<0.001), and HbA1c (r=0.576; p<0.001) in all patients. While a strong positive association was seen for blood urea nitrogen as a marker for kidney function both at baseline (r= 0.728; p=0.000) and follow up (r=0.747; p=0.001). Multiple logistic regression controlling for age showed that KIM1 was independently associated with BUN (r=0.727; p<0.001), creatinine (r=0.510; p<0.001) and HbA1c (r=0.401; p=0.008) in all groups.

Conclusion:

Rising KIM-1 levels with progressive kidney damage with or without derangement of kidney function is reported in this study. This finding may pave a way towards identifying KIM1 as a prognostic marker for kidney injury.

The origin of plasma neutrophil gelatinase-associated lipocalin in cardiac surgery

Background

Acute kidney injury (AKI) is common after heart surgery. Neutrophil gelatinase-associated lipocalin (NGAL) is produced in injured kidney. NGAL has been used as an early plasma biomarker for AKI in patients undergoing heart surgery. Neutrophils contain all isoforms (25-kDa, 45-kDa and 145-kDa) but the kidney produces almost exclusively the 25-kDa isoform of NGAL. We investigated first, whether there is association between NGAL and neutrophil activation, and second whether activated neutrophils are a significant source of circulating NGAL in plasma in patients undergoing cardiac surgery.

Methods

Two separate patient cohorts were studied: 1) the “kinetic cohort” (n = 29) and 2) the “FINNAKI cohort” (n = 306). As NGAL is strictly co-localized with lactoferrin in neutrophils, NGAL and lactoferrin were measured with enzyme-linked immunosorbent assay in all patients. In sixty-one patients of the “FINNAKI cohort” Western blot was used to separate NGAL isoforms according to their molecular size. Mann-Whitney U, Kruskal-Wallis H, Pearson’s and Spearman’s tests were used as appropriate.

Results

There was strong intraoperative association between NGAL and lactoferrin at all four time-points in the “kinetic cohort”. In the “FINNAKI cohort”, NGAL and lactoferrin concentrations correlated preoperatively (R = 0.59, p < 0.001) and at admission to the intensive care unit (R = 0.69, p < 0.001). At admission to intensive care unit, concentrations of NGAL and lactoferrin were higher in AKI than in non-AKI patients (NGAL: p < 0.001; lactoferrin: p < 0.029). In Western blot analyses, neutrophil specific 45-kDa isoform (median 41% [IQR 33.3–53.1]) and mostly neutrophil derived 145-kDa isoform (median 53.5% [IQR 44.0–64.9%]) together represented over 90% of total NGAL in plasma. Potentially kidney derived NGAL isoform (25-kDa) accounted for only 0.9% (IQR 0.3 – 3.0%) of total NGAL in plasma. There were no statistically significant differences in the distribution of NGAL isomers between AKI and non-AKI patients.

Conclusions

Plasma NGAL during cardiac surgery is associated with neutrophil activation. Based on molecular size, the majority of circulating NGAL is derived from neutrophils. Neutrophil activation is a confounding factor when interpreting increased plasma NGAL in cardiac surgery.

Urinary N-acetyl-beta-d-glucosaminidase (NAG) with neutrophil gelatinase-associated lipocalin (NGAL) improves the diagnostic value for proximal tubule damage in diabetic kidney disease

Screening for diabetic kidney disease (DKD) remains a challenge; however, there has been an ongoing research to investigate the diagnostic value of different biomarkers to identify DKD. The aim of this study was to assess the diagnostic value of both N-acetyl-beta-d-glucosaminidase (NAG) and neutrophil gelatinase-associated lipocalin (NGAL) in the progression of DKD. This cross-sectional case-control study included 92 type 2 diabetic patients with or without DKD. Urinary NAG and NGAL were measured to evaluate their diagnostic values as biochemical markers related to DKD. Both urinary NAG and NGAL levels were significantly higher among patients with DKD. In multiple linear regression analysis, NAG showed a positive significant association with NGAL in the three different adjusted models, while no significant correlation with fasting blood glucose, glycated hemoglobin, serum creatinine, estimated glomerular filtration rate, and albumin creatinine ratio were observed. The area under the curve for NGAL was 0.659 (p = 0.01) and 0.564 (p = 0.297) for NAG in DKD patients. This study demonstrates the association between urinary NAG and NGAL as a tubular damage marker for DKD although longitudinal studies are needed to evaluate its diagnostic value.

Biomarkers for individualized dosage adjustments in immunosuppressive therapy using calcineurin inhibitors after organ transplantation

Calcineurin inhibitors (CNIs), such as cyclosporine A and tacrolimus, are widely used immunosuppressive agents for the prevention of post-transplantation rejection and have improved 1-year graft survival rates by up to 90%. However, CNIs can induce severe reactions, such as acute or chronic allograft nephropathy, hypertension, and neurotoxicity. Because CNIs have varied bioavailabilities, narrow therapeutic ranges, and individual propensities for toxic effects, therapeutic drug monitoring is necessary for all CNIs. Identifying the genetic polymorphisms in drug-metabolizing enzymes will help to determine personalized dosage regimens for CNIs, as CNIs are substrates for CYP3A5 and P-glycoprotein (P-gp, MDR1). CNIs are often concomitantly administered with voriconazole or proton pump inhibitors (PPIs), giving rise to drug interaction problems. Voriconazole and PPIs can increase the blood concentrations of CNIs, and both are primarily metabolized by CYP2C19. Thus, it is expected that interactions between CNIs and voriconazole or PPI would be affected by CYP2C19 and CYP3A5 polymorphisms. CNI-induced acute kidney injury (AKI) is a serious complication of transplantations. Neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule 1 (KIM-1) are noninvasive urinary biomarkers that are believed to be highly sensitive to CNI-induced AKI. In this article, we review the adverse events and pharmacokinetics of CNIs and the biomarkers related to CNIs, including CYP3A5, CYP2C19, MDR1, NGAL, and KIM-1. We hope that these data will help to identify the optimal biomarkers for monitoring CNI-based immunosuppressive therapy after organ transplantation.

A novel strategy for identifying early acute kidney injury in pediatric hematopoietic stem cell transplantation

Acute kidney injury (AKI) is a common complication in pediatric hematopoietic stem cell transplantation (HSCT). Serum creatinine is an imprecise biomarker of AKI. We hypothesized that combining creatinine with serum cystatin C (cysC) and urinary neutrophil gelatinase-associated lipocalin (NGAL) more effectively characterizes AKI during the first 28 days of HSCT and better identifies patients at risk of adverse outcomes than creatinine alone. We prospectively assessed the type and severity of AKI in 80 consecutive allogeneic HSCT patients using weekly creatinine, cysC, and NGAL. We combined the biomarkers to define 7 Composite Types of AKI, including All Positive AKI (simultaneously detected creatinine, cysC, and NGAL AKI). Outcomes included renal replacement therapy and transplant-related mortality. In all, 75% of patients had AKI by at least one measure; 33% developed >1 type of AKI. Mild AKI often preceded Severe AKI. Patients with creatinine or NGAL AKI that were Severe or Repeated tended to have worse outcomes. The five patients with All Positive AKI had the highest rates of morbidity and mortality. AKI evaluation with creatinine, cysC, and NGAL provides a comprehensive profile of early AKI and narrowly identifies patients at highest risk of adverse outcomes, providing opportunities for early, impactful intervention.

Comparative Assessment of uNGAL, uNAG and Cystatin C As Early Biomarkers in Renal Post-Transplant Patients

Urinary neutrophil gelatinase-associated lipocalin (uNGAL), urinary N-acetyl-bd-glucosaminidase (NAG), urinary α1-microglobulin/creatinine ratio and cystatin C have been suggested as potential early markers of delayed graft function (DGF) following kidney transplantation. We conducted a prospective study in 50 consecutive kidney transplant recipients to evaluate serial changes of these biomarkers within the first week after transplantation and assess their performance in predicting DGF (dialysis requirement during initial post-transplant week) and graft function throughout the first year. Urine samples were collected on post-transplantation days 0, 1, 2, 4, and 7. Statistical analysis: Linear mixed and multivariable regression models, receiver-operating characteristic (ROC), and areas under ROC curves were used. At all-time points, mean urinary NGAL levels were significantly higher in patients developing DGF. Shortly after transplantation (3-6 h), uNGAL and uNAG values were higher in DGF recipients (on average +242 ng/mL; NAG – 6.8 U/mmol creatinine, considering mean dialysis time of 4.1 years) and rose further in the following days, contrasting with prompt function recipients. On Day-1 uNGAL levels accurately predicted DGF (AUC-ROC = 0.93), with a performance higher than serum creatinine (AUC-ROC = 0.76), and similar to cystatin C (AUC-ROC = 0.95). Multivariable analyses revealed that uNGAL levels at days 4 and 7 were strongly associated with one-year serum creatinine level. Urinary NGAL, serum cystatin C is an early marker of graft injury and is independently associated with dialysis requirement within one week after transplantation and one-year graft function.

Glycogen Metabolism and Rheumatoid Arthritis: The Role of Glycogen Synthase 1 in Regulation of Synovial Inflammation via Blocking AMP-Activated Protein Kinase Activation

Objective

To investigate the role of glycogen metabolism in regulating rheumatoid fibroblast-like synoviocyte (FLS)-mediated synovial inflammation and its underlying mechanism.

Methods

FLSs were separated from synovial tissues (STs) obtained from rheumatoid arthritis (RA) patients. Glycogen content was determined by periodic acid Schiff staining. Protein expression was analyzed by Western blot or immunohistochemistry. Gene expression of cytokines and matrix metalloproteinases (MMPs) was evaluated by quantitative real-time PCR. FLS proliferation was detected by EdU incorporation. Migration and invasion were measured by Boyden chamber assay.

Results

Glycogen levels and glycogen synthase 1 (GYS1) expression were significantly increased in the ST and FLSs of RA patients. TNF-α or hypoxia induced GYS1 expression and glycogen synthesis in RA FLSs. GYS1 knockdown by shRNA decreased the expression of IL-1β, IL-6, CCL-2, MMP-1, and MMP-9 and proliferation and migration by increasing AMP-activated protein kinase (AMPK) activity in RA FLS. AMPK inhibitor or knockdown AMPK could reverse the inhibitory effect of GYS1 knockdown on the inflammatory response in RA FLSs; however, an AMPK agonist blocked RA FLS activity. We further determined that hypoxia-inducible factor-1α mediates TNF-α- or hypoxia-induced GYS1 expression and glycogen levels. Local joint depletion of GYS1 or intraperitoneal administration with an AMPK agonist ameliorated the severity of arthritis in rats with collagen-induced arthritis.

Conclusion

Our data demonstrate that GYS1-mediated glycogen accumulation contributes to FLS-mediated synovial inflammation in RA by blocking AMPK activation. In our knowledge, this is a first study linking glycogen metabolism to chronic inflammation. Inhibition of GYS1 might be a novel therapeutic strategy for chronic inflammatory arthritis, including RA.

NMR-based urine metabolic profiling and immunohistochemistry analysis of nephron changes in a mouse model of hypoxia-induced acute kidney injury

Acute kidney injury can be caused by multiple factors, including sepsis, respiratory failure, heart failure, trauma, or nephrotoxic medications, among others. Here, a mouse model was used to investigate potential urinary metabolic biomarkers of hypoxia-induced AKI. Urine metabolic profiles of 48 Swiss Webster mice were assessed using nuclear magnetic resonance spectroscopy (NMR) for 7 days following 72 h exposure to a hypoxic 6.5% oxygen environment. Histological analyses indicated a lack of gross nephron structural changes in the aftermath of hypoxia. Immunohistochemical (IHC) analyses, however, indicated elevated expression of protein injury biomarkers in distal and proximal tubules but not glomeruli. Kidney injury molecule-1 levels peaked in distal tubules at 72 h and were still increasing in proximal tubules at 7 days posthypoxia, whereas cystatin C levels were elevated at 24 h but decreased thereafter, and were elevated and still increasing in proximal tubules at 7 days posthypoxia. Neutrophil gelatinase-associated lipocalin levels were modestly elevated from 24 h to 7 days posthypoxia. NMR-based metabolic profiling revealed that urine metabolites involved in energy metabolism and associated biosynthetic pathways were initially decreased at 24 h posthypoxia, consistent with metabolic suppression as a mechanism for cell survival, but were significantly elevated at 48 and 72 h posthypoxia, indicating a burst in organism metabolism associated with reactivation of cellular energetics during recovery after cessation of hypoxia and return to a normoxic environment. The IHC results indicated that kidney injury persists long after plasma and urine biomarkers of hypoxia return to normal values.

Kidney injury molecule-1 staining in renal allograft biopsies 10 days after transplantation is inversely correlated with functioning proximal tubular epithelial cells

Background

Kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) are promising biomarkers for monitoring delayed graft function (DGF) after kidney transplantation. Here we investigated localization and distribution of KIM-1 and NGAL staining in renal allograft biopsies and studied their association with histological features, functional DGF (fDGF) and the tubular function slope (TFS), a functioning proximal tubular epithelial cell (PTEC) marker.

Methods

Day 10 protocol biopsies of 64 donation after circulatory death recipients were stained for KIM-1 and NGAL and the positive area was quantified using ImageJ software. Biopsies were scored according to Banff and acute tubular necrosis (ATN) criteria. A 99mtechnetium-mercaptoacetyltriglycine (99mTc-MAG3)-renography was performed to calculate TFS.

Results

KIM-1 staining was located on the brush border of tubular epithelial cells (TECs) and correlated with denudation, while NGAL was present more focally in a cytoplasmic distribution. KIM-1 and NGAL staining were not correlated and no co-localization was observed. Quantitative stainings were not associated with fDGF, but KIM-1 tended to be higher in patients with prolonged fDGF (≥21 days; P = 0.062). No correlation was observed between the quantitative tissue stainings and urinary KIM-1 or NGAL. Quantitative KIM-1 staining was inversely correlated with the TFS (Spearman's ρ = -0.53; P < 0.001), whereas NGAL was not. The latter finding might be because cortical NGAL staining is dependent on filtration and subsequent reabsorption by functioning PTECs. Staining of NGAL was indeed restricted to PTECs, as shown by co-localization with a PTEC-specific lectin.

Conclusions

KIM-1 and NGAL staining showed different localization and distribution. Quantitative KIM-1 staining was inversely correlated with functioning PTECs.

Hepatocyte-Derived Lipocalin 2 Is a Potential Serum Biomarker Reflecting Tumor Burden in Hepatoblastoma

Hepatoblastoma (HB) is the most common pediatric liver malignant tumor. Previously, we reported co-activation of β-catenin and Yes-associated protein-1 (YAP1) in 80% of HB. Hepatic co-expression of active β-catenin and YAP1 via sleeping beauty transposon/transposase and hydrodynamic tail vein injection led to HB development in mice. Here, we identify lipocalin 2 (Lcn2) as a target of β-catenin and YAP1 in HB and show that serum Lcn2 values positively correlated with tumor burden. Lcn2 was strongly expressed in HB tumor cells in our mouse model. A tissue array of 62 HB cases showed highest LCN2 expression in embryonal and lowest in fetal, blastemal, and small cell undifferentiated forms of HB. Knockdown of LCN2 in HB cells had no effect on cell proliferation but reduced NF-κB reporter activity. Next, liver-specific Lcn2 knockout (KO) mice were generated. No difference in tumor burden was observed between Lcn2 KO mice and wild-type littermate controls after sleeping beauty transposon/transposase and hydrodynamic tail vein injection delivery of active YAP1 and β-catenin, although Lcn2 KO mice with HB lacked any serum Lcn2 elevation, demonstrating that transformed hepatocytes are the source of serum Lcn2. More blastemal areas and inflammation were observed within HB in Lcn2 KO compared with wild-type tumors. In conclusion, Lcn2 expressed in hepatocytes appears to be dispensable for the pathogenesis of HB. However, transformed hepatocytes secrete serum Lcn2, making Lcn2 a valuable biomarker for HB.

Undiagnosed Kidney Injury in Uninsured and Underinsured Diabetic African American Men and Putative Role of Meprin Metalloproteases in Diabetic Nephropathy

Diabetes is the leading cause of chronic kidney disease. African Americans are disproportionately burdened by diabetic kidney disease (DKD) and end stage renal disease (ESRD). Disparities in DKD have genetic and socioeconomic components, yet its prevalence in African Americans is not adequately studied. The current study used multiple biomarkers of DKD to evaluate undiagnosed DKD in uninsured and underinsured African American men in Greensboro, North Carolina. Participants consisted of three groups: nondiabetic controls, diabetic patients without known kidney disease, and diabetic patients with diagnosed DKD. Our data reveal undiagnosed kidney injury in a significant proportion of the diabetic patients, based on levels of both plasma and urinary biomarkers of kidney injury, namely, urinary albumin to creatinine ratio, kidney injury molecule-1, cystatin C, and neutrophil gelatinase-associated lipocalin. We also found that the urinary levels of meprin A, meprin B, and two kidney meprin targets (nidogen-1 and monocytes chemoattractant protein-1) increased with severity of kidney injury, suggesting a potential role for meprin metalloproteases in the pathophysiology of DKD in this subpopulation. The study also demonstrates a need for more aggressive tests to assess kidney injury in uninsured diabetic patients to facilitate early diagnosis and targeted interventions that could slow progression to ESRD.

Distinct morphological features of acute tubular injury in renal allografts correlate with clinical outcome

Acute tubular injury (ATI) is common in renal allografts and is related to inferior long-term allograft function. However, it is unknown which of the morphological features of ATI can predict outcome and how they should be graded. Here, we examine features of ATI systematically in protocol biopsies and biopsies for cause to define the most predictive features. Analyses included 521 protocol biopsies taken at 6 wk, 3 mo, and 6 mo after transplantation and 141 biopsies for cause from 204 patients. Features of ATI included brush border loss, tubular epithelial lucency, flattening, pyknosis, nuclei loss, and luminal debris, each graded semiquantitatively. Additional immunohistochemical stainings were performed for markers of cell injury (neutrophil gelatinase-associated lipocalin), cell death [cleaved caspase-3, fatty acid-coenzyme A ligase 4 (FACL4)], and proliferation (K_i-67). Interobserver reliability was good for pyknosis, flattening, and brush border loss and poor for lucency, nuclei loss, and luminal debris. In protocol biopsies between 6 wk and 6 mo, the degree of ATI remained virtually unchanged. Biopsies for cause had generally higher injury scores. Deceased donor source, delayed graft function, ganciclovir/valganciclovir treatment, and urinary tract infection correlated with ATI. The degree of pyknosis, flattening, and brush border loss correlated best with impaired allograft function. FACL4 expression was observed in areas of ATI. Only patients with K_i-67 expression showed stable or improved allograft function in the longitudinal assessment. Reliable assessment of ATI is possible by semiquantitative grading of tubular epithelial cell brush border loss, flattening, and pyknosis. Examination of K_i-67 expression can help determine the potential for recovery from this damage.

Urinary neutrophil gelatinase-associated lipocalin is an excellent predictor of mortality in intensive care unit patients

Objectives:

To assess urine neutrophil gelatinase-associated lipocalin (uNGAL) level as a potential predictor of acute kidney injury (AKI), and both intensive care unit (ICU) and in-hospital mortality.

Methods:

Patients presenting to our ICU with a systolic blood pressure (SBP) <90 mmHg or mean arterial pressure (MAP) <65 mmHg, and no prior kidney disease were followed prospectively. Baseline data were collected on patient demographics, admission diagnosis, APACHE II and SOFA scores, SBP, MAP, serum creatinine and cystatin C, and uNGAL. Patients were monitored throughout hospitalization, including daily uNGAL, serum creatinine and cystatin C, and continuous MAP. Bivariate analysis compared those dying in the ICU and in-hospital versus survivors; with hierarchical binary logistic regression used to identify predictors of mortality. Areas under receiver-operating-characteristic curves (AUC) were used to measure sensitivity and specificity at different uNGAL thresholds.

Results:

Among 75 patients followed, 16 died in the ICU, and another 24 prior to hospital discharge. Mortality rates were greatest in trauma and sepsis patients. The ICU survivors differed from non-survivors in almost all clinical variables; but only 2 predicted ICU mortality on multivariate analysis: day one uNGAL (p=0.01) and 24-hour APACHE II score (p=0.07). Only the APACHE II score significantly predicted in-hospital mortality (p=0.003). The AUC for day one uNGAL was greater for ICU (AUC=0.85) than in-hospital mortality (AUC=0.74).

Conclusions:

Day one uNGAL is a highly accurate predictor of ICU, but less so for in-hospital mortality.

Urinary neutrophil gelatinase-associated lipocalin as a marker for disease activity in lupus nephritis

The neutrophil gelatinase-associated lipocalin (NGAL) has been emerging as a novel biomarker of acute kidney injury while its value in lupus nephritis is uncertain. The aim of this study was to assess urinary NGAL levels as a marker for disease activity in patients with lupus nephritis.This study included 70 systemic lupus erythematosus (SLE) patients; 50 with active lupus nephritis (LN) and 20 without as well as 20 matched controls. The neutrophil gelatinase-associated lipocalin (NGAL) in both serum and urine samples was measured by enzyme-linked immunosorbent assay (ELISA). Patients with active LN received standard treatment then assessed for response as well as the value of urinary NGAL (uNGAL). Our results revealed that, The SLE patients with or without LN had an elevated urinary NGAL as compared to controls (p < 0.000) and the mean of uNGAL was (20.67 ± 5.34),(10.63 ± 3.53),(5.65 ± 2.49) respectively. Furthermore,Urinary NGAL levels in LN patients were significantly higher than those in non-LN patients (P < 0.0001). In the ROC curve analysis , the diagnostic performance of uNGAL for discriminating patients with nephritis from those without nephritis showed that the best cutoff value was 13.66 ng/ml ,sensitivity 92%,specificity 75%,area undercurve (0.959) and (P < 0.0001). Measurement of urinary NGAL levels showed an excellent diagnostic performance for discriminating patients with LN from SLE without nephritis.

Neutrophil gelatinase-associated lipocalin reflects inflammation and is not a reliable renal biomarker in neonates and infants after cardiopulmonary bypass: a prospective case-control study

Introduction Acute kidney injury is a frequent complication after cardiac surgery with cardiopulmonary bypass in infants. Neutrophil gelatinase-associated lipocalin has been suggested to be a promising early biomarker of impending acute kidney injury. On the other hand, neutrophil gelatinase-associated lipocalin has been shown to be elevated in systemic inflammatory diseases without renal impairment. In this secondary analysis of data from our previous study on acute kidney injury after infant cardiac surgery, our hypothesis was that neutrophil gelatinase-associated lipocalin may be associated with surgery-related inflammation.

METHODS

We prospectively enrolled 59 neonates and infants undergoing cardiopulmonary bypass surgery for CHD and measured neutrophil gelatinase-associated lipocalin in plasma and urine and interleukin-6 in the plasma. Values were correlated with postoperative acute kidney injury according to the paediatric Renal-Injury-Failure-Loss-Endstage classification.

RESULTS

Overall, 48% (28/59) of patients developed acute kidney injury. Of these, 50% (14/28) were classified as injury and 11% (3/28) received renal replacement therapy. Both plasma and urinary neutrophil gelatinase-associated lipocalin values were not correlated with acute kidney injury occurrence. Plasma neutrophil gelatinase-associated lipocalin showed a strong correlation with interleukin-6. Urinary neutrophil gelatinase-associated lipocalin values correlated with cardiopulmonary bypass time.

CONCLUSION

Our results suggest that plasma and urinary neutrophil gelatinase-associated lipocalin values are not reliable indicators of impending acute kidney injury in neonates and infants after cardiac surgery with cardiopulmonary bypass. Inflammation may have a major impact on plasma neutrophil gelatinase-associated lipocalin values in infant cardiac surgery. Urinary neutrophil gelatinase-associated lipocalin may add little prognostic value over cardiopulmonary bypass time.