Neutrophil gelatinase-associated lipocalin (NGAL): a new marker of kidney disease

Predictive value of plasma neutrophil gelatinase-associated lipocalin for acute kidney injury in intensive care unit patients after major non-cardiac surgery

AIM

The performance of plasma neutrophil gelatinase-associated lipocalin (pNGAL) for prediction of acute kidney injury (AKI) in non-cardiac surgical patients has not been well described. This study investigates the use of pNGAL for early detection of AKI in patients admitted to an intensive care unit (ICU) after major or ultra-major non-cardiac surgery.

METHODS

A total of 151 patients were recruited. Blood samples at 0 h and 6 h post-ICU admission were collected. Primary outcome was occurrence of AKI within 48 h of ICU admission defined using Acute Kidney Injury Network (AKIN) classification.

RESULTS

Forty-five (29.8%) patients developed AKI within 48 h of ICU admission. Among them, 22, 14, and nine were classified as AKIN Stage 1, 2, and 3 respectively. pNGAL levels at 0 h and 6 h were significantly related to AKI severity. The AUROC for pNGAL at 0 h and 6 h increased with AKI severity (AKIN stage ≥1 0.671 ± 0.048 and 0.691 ± 0.047; stage ≥2 0.737 ± 0.055 and 0.796 ± 0.048; stage 3 0.829 ± 0.072 and 0.860 ± 0.065, respectively) and requirement of renal replacement therapy (0.880 ± 0.059 & 0.837 ± 0.088). Change of pNGAL from 0 h to 6 h showed no advantage in predictive power compared with pNGAL level at 0 h or 6 h alone. The addition of pNGAL into clinical AKI prediction model could only provide marginal benefit.

CONCLUSION

pNGAL correlated with severity of AKI and requirement of renal replacement therapy in ICU patients who received major or ultra-major non-cardiac surgery. However, the benefit of adding pNGAL into clinical AKI prediction model is marginal.

Interleukin 18 and neutrophil-gelatinase associated lipocalin in assessment of the risk of contrast-induced nephropathy in children

The aim of the study was to determine the usefulness of interleukin 18 (IL-18) and neutrophil-gelatinase associated lipocalin (NGAL) in the risk assessment of contrast nephropathy in children. The study included patients among whom radiological examinations were performed using intravascular contrast agent. The material consisted of 33 children (19 girls, 14 boys) aged 6.37 ±5.41 years. 20/33 (61%) of patients had hydronephrosis, 9/33 (27%) had other urinary tract defects referred as “no hydronephrosis” and 4/33 (12%) had urolithiasis. NGAL determination was performed with the use of Human Lipocalin-2 / NGAL Immunoassay. To determine the concentration of human IL-18 an ELISA Kit (MBL International Corporation) was used. There were no statistically significant differences in the concentrations of NGAL and IL-18 in serum determined before the procedure, and after the administration of contrast agent. Concentrations of NGAL and IL-18 were determined in urine three times: before the procedure, 2-4 hours after administration of the contrast agent, and 48 hours after the performed procedure. The analysis showed that the concentration of IL-18 and NGAL in urine did not differ significantly in three consecutive preformed measurements. The study has also found no statistically significant differences between serum creatinine before and 48 hours after injection of contrast. Implementation of new biomarkers such as NGAL and IL-18 expands the possibilities of renal function assessment in children undergoing radiological procedures using contrast agents. In examined children with normal or slightly impaired renal function they did not demonstrate the risk of contrast nephropathy.

Heat stroke

Heat stroke is a life-threatening condition clinically diagnosed as a severe elevation in body temperature with central nervous system dysfunction that often includes combativeness, delirium, seizures, and coma. Classic heat stroke primarily occurs in immunocompromised individuals during annual heat waves. Exertional heat stroke is observed in young fit individuals performing strenuous physical activity in hot or temperature environments. Long-term consequences of heat stroke are thought to be due to a systemic inflammatory response syndrome. This article provides a comprehensive review of recent advances in the identification of risk factors that predispose to heat stroke, the role of endotoxin and cytokines in mediation of multi-organ damage, the incidence of hypothermia and fever during heat stroke recovery, clinical biomarkers of organ damage severity, and protective cooling strategies. Risk factors include environmental factors, medications, drug use, compromised health status, and genetic conditions. The role of endotoxin and cytokines is discussed in the framework of research conducted over 30 years ago that requires reassessment to more clearly identify the role of these factors in the systemic inflammatory response syndrome. We challenge the notion that hypothalamic damage is responsible for thermoregulatory disturbances during heat stroke recovery and highlight recent advances in our understanding of the regulated nature of these responses. The need for more sensitive clinical biomarkers of organ damage is examined. Conventional and emerging cooling methods are discussed with reference to protection against peripheral organ damage and selective brain cooling.

Role of new biomarkers for predicting renal scarring in vesicoureteral reflux: NGAL, KIM-1, and L-FABP

BACKGROUND

Reflux nephropathy is the most serious complication of vesicoureteral reflux (VUR). The aim of this study was to assess the role of urinary levels of neutrophil-gelatinase-associated lipocalin (NGAL),kidney injury molecule-1 (KIM-1), and liver-type fatty-acid-binding protein (L-FABP) in the early diagnosis of reflux nephropathy in patients with VUR.

METHODS

This study assessed 123 patients with primary VUR and 30 healthy children as a control group. The children were divided into five groups: Group A, patients with VUR and renal parenchymal scarring (RPS); Group B, patients with VUR and without RPS; Group C, patients with RPS and resolved VUR; Group D, patients with resolved VUR and without RPS; Group E, healthy reference group.

RESULTS

Median urinary NGAL (uNGAL)/Creatinine (Cr) was significantly higher in patients with than those without RPS and the control group (p = 0.0001). Median uKIM-1/Cr was similar in all groups (p = 0.417). Median uL-FABP/Cr was significantly higher in patients with RPS than in the reference group (p < 0.05).

CONCLUSIONS

Urinary NGAL levels may be used as a noninvasive diagnostic marker for predicting renal scarring in reflux nephropathy.

Salivary markers of kidney function - Potentials and limitations

Saliva can be collected non-invasively, repeatedly and without trained personnel. It is a promising diagnostic body fluid with clinical use in endocrinology and dentistry. For decades, it is known that saliva contains also urea, creatinine and other markers of renal function. Clinical studies have shown that the salivary concentrations of these markers could be useful for the assessment of kidney function without the need of blood collection. This article summarizes the clinical and experimental data on the use of saliva as a diagnostic fluid in nephrology and points out the advantages, pitfalls, technical requirements and future perspective for the use of saliva as a novel potential diagnostic biofluid.

Strategy and rationale for urine collection protocols employed in the NEPTUNE study

Background

Glomerular diseases are potentially fatal, requiring aggressive interventions and close monitoring. Urine is a readily-accessible body fluid enriched in molecular signatures from the kidney and therefore particularly suited for routine clinical analysis as well as development of non-invasive biomarkers for glomerular diseases.

Methods

The Nephrotic Syndrome Study Network (NEPTUNE; ClinicalTrials.gov Identifier NCT01209000) is a North American multicenter collaborative consortium established to develop a translational research infrastructure for nephrotic syndrome. This includes standardized urine collections across all participating centers for the purpose of discovering non-invasive biomarkers for patients with nephrotic syndrome due to minimal change disease, focal segmental glomerulosclerosis, and membranous nephropathy. Here we describe the organization and methods of urine procurement and banking procedures in NEPTUNE.

Results

We discuss the rationale for urine collection and storage conditions, and demonstrate the performance of three experimental analytes (neutrophil gelatinase-associated lipocalin [NGAL], retinol binding globulin, and alpha-1 microglobulin) under these conditions with and without urine preservatives (thymol, toluene, and boric acid). We also demonstrate the quality of RNA and protein collected from the urine cellular pellet and exosomes.

Conclusions

The urine collection protocol in NEPTUNE allows robust detection of a wide range of proteins and RNAs from urine supernatant and pellets collected longitudinally from each patient over 5 years. Combined with the detailed clinical and histopathologic data, this provides a unique resource for exploration and validation of new or accepted markers of glomerular diseases.

Trial registration

ClinicalTrials.gov Identifier NCT01209000

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-015-0185-3) contains supplementary material, which is available to authorized users.

Plasma Neutrophil Gelatinase Associated Lipocalin (NGAL) - Early Biomarker for Acute Kidney Injury in Critically Ill Patients

Introduction

NGAL (Neutrophil Gelatinase Associated Lipocalin) is a biomarker recently introduced into clinical practice for the early diagnosis of acute kidney injury (AKI). The aim of this study was to correlate the plasmatic NGAL value determined at admission with clinical progression and severity of AKI in critically ill patients.

Material and method

Thirty two consecutive critically ill adult patients at risk of developing AKI (trauma, sepsis), admitted in Intensive Care Unit of the Clinical County Emergency Hospital Mures, between January to March 2015 were enrolled in the study. For each patient included in the study plasma NGAL levels were determined on admission, and these were correlated with the degree of AKI development (according to AKIN criteria) at 48 hours and 5 days post admission. The discriminatory power of NGAL, creatinine, creatinine clearance and corrected creatinine (depending on water balance) were determined using the ROC (receiver-operating characteristic) and likelihood ratios.

Results

ROC curve analysis showed a better discriminatory capacity in terms of early diagnosis of AKI for NGAL (AUC=0.81 for NGAL, AUC=0.59 for creatinine, AUC=0.62 for corrected creatinine, AUC=0.29 for creatinine clearance). The value of likelihood ratio was also significantly higher for NGAL (3.01±2.73 for NGAL, 1.27±1.14 for creatinine, 1.78±1.81 for corrected creatinine, and 0.48±0.33 for creatinine clearance).

Conclusions

NGAL biomarker has a better discrimination capacity for early prediction of acute kidney injury compared to previously used markers.

Targeting of Gamma-Glutamyl-Cysteine Ligase by miR-433 Reduces Glutathione Biosynthesis and Promotes TGF-β-Dependent Fibrogenesis

AIMS

Glutathione (GSH) is the main antioxidant against cell damage. Several pathological states course with reduced nucleophilic tone and perturbation of redox homeostasis due to changes in the 2GSH/GSSG ratio. Here, we investigated the regulation of the rate-limiting GSH biosynthetic heterodimeric enzyme γ-glutamyl-cysteine ligase (GCL) by microRNAs (miRNAs).

RESULTS

"In silico" analysis of the 3'- untranslated regions (UTRs) of both catalytic (GCLc) and regulatory (GCLm) subunits of GCL enabled an identification of miR-433 as a strong candidate for the targeting of GCL. Transitory overexpression of miR-433 in human umbilical vein endothelial cells (HUVEC) showed a downregulation of both GCLc and GCLm in a nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-independent manner. Increases in pro-oxidant stimuli such as exposure to hydrogen peroxide or GSH depletion in endothelial and hepatic cells caused an expected increase in GCLc and GCLm protein expression and abrogation of miR-433 levels, thus supporting a cross-regulation of these pathways. Treatment of HUVEC with miR-433 resulted in reduced antioxidant and redox potentials, increased S-glutathionylation, and reduced endothelial nitric oxide synthase activation. In vivo models of renal and hepatic fibrosis were associated with transforming growth factor β1 (TGF-β1)-related reduction of GCLc and GCLm levels that were miR-433 dependent.

INNOVATION AND CONCLUSION

We describe for the first time an miRNA, miR-433, capable of directly targeting GCL and promoting functional consequences in endothelial physiology and fibrotic processes by decreasing GSH levels.

Biomarkers of Kidney Injury Among Nicaraguan Sugarcane Workers

BACKGROUND

In Central America, an epidemic of chronic kidney disease of unknown cause disproportionately affects young male agricultural workers.

STUDY DESIGN

Longitudinal cohort study.

SETTING & PARTICIPANTS

284 sugarcane workers in 7 jobs were recruited from one company in northwestern Nicaragua. Blood and urine samples were collected before and near the end of the 6-month harvest season.

PREDICTORS

Job category (cane cutter, seeder, seed cutter, agrichemical applicator, irrigator, driver, and factory worker); self-reported water and electrolyte solution intake.

OUTCOMES & MEASUREMENTS

Changes in levels of urinary kidney injury biomarkers normalized to urine creatinine level, including neutrophil gelatinase-associated lipocalin (NGAL), interleukin 18 (IL-18), N-acetyl-β-d-glucosaminidase (NAG), and albumin; serum creatinine-based estimated glomerular filtration rate (eGFR).

RESULTS

Mean eGFR was 113 mL/min/1.73 m(2) and <5% of workers had albuminuria. Field workers had increases in NGAL and IL-18 levels that were 1.49 (95% CI, 1.06 to 2.09) and 1.61 (95% CI, 1.12 to 2.31) times as high, respectively, as in non-field workers. Cane cutters and irrigators had the greatest increases in NGAL levels during the harvest, whereas cane cutters and seeders had the greatest increases in IL-18 levels. Electrolyte solution consumption was associated with lower mean NGAL and NAG levels among cane cutters and lower mean IL-18 and NAG levels among seed cutters; however, there was no overall effect of hydration among all workers. On average, workers with the largest increases in NGAL and NAG levels during the harvest had declines in eGFRs of 4.6 (95% CI, 1.0 to 8.2) and 3.1 (95% CI, -0.6 to 6.7) mL/min/1.73 m(2), respectively.

LIMITATIONS

Surrogate exposure measure, loss to follow-up.

CONCLUSIONS

Results are consistent with the hypothesis that occupational heat stress and volume depletion may be associated with the development of kidney disease, and future studies should directly measure these occupational factors. The presence of urine tubular injury markers supports a tubulointerstitial disease that could occur with repeated tubular injury.

Early Markers of Tubulointerstitial Fibrosis in Children With Idiopathic Nephrotic Syndrome: Preliminary Report

Tubulointerstitial fibrosis and tubular atrophy play a crucial role in the pathogenesis of chronic kidney disease (CKD). They are also major determinants in chronic kidney disease development and progression in patients with primary renal diseases characterized by persistent or recurrent proteinuria. The purpose of the study was to assess urinary excretion of alpha-glutathione S-transferase (alpha-GST), pi-glutathione S-transferase (pi-GST), neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and serum NGAL level in children with idiopathic nephrotic syndrome (INS).

PATIENTS AND METHODS

the study group comprised of 39 children with INS and the control group consisted of 20 healthy children. A total of 23 patients were affected with steroid-dependent nephrotic syndrome (SDNS) and 16 with steroid-resistant nephrotic syndrome (SRNS). In the majority of patients, a histopathologic examination revealed minimal change disease (MCD)-25 (64%). Focal segmental glomerulosclerosis (FSGS), mesangioproliferative glomerulonephritis (MesPGN), membranoproliferative glomerulonephritis (MPGN), and membranous glomerulonephritis (MGN) were diagnosed in 4 (10.3 %), 6 (15.5%), 2 (5.1%), and 2 (5.1%) children, respectively. Urinary alpha-GST, urinary pi-GST, urinary KIM-1, and urinary and serum NGAL concentrations were measured using specific enzyme-linked immunosorbent assay. The urinary results were expressed in nanograms per milligram of creatinine (ng/mg).

RESULTS

The authors observed significantly higher levels of urinary alpha-GST/creatinine ratio (P = 0.03), urinary KIM-1/creatinine ratio (P < 0.02), serum NGAL level (P < 0.01), and urinary NGAL/creatinine ratio (P = 0.02) in children with INS compared with controls. The median values of urinary pi-GST/creatinine ratio in children with INS and controls did not differ significantly. In children with SRNS, the median values of urinary NGAL/creatinine ratio (P = 0.02) and urinary KIM-1/creatinine ratio (P = 0.02) were significantly higher compared with children with SDNS. The authors noted significant positive correlation between KIM-1/creatinine ratio and proteinuria (r = 0.56, P < 0.05). The analysis of alpha-GST/creatinine ratio, pi-GST/creatinine ratio, sNGAL, and uNGAL/creatinine ratio concerning the histopathologic examination, the duration of the disease, and number of relapses did not show any significant differences.

CONCLUSIONS

1. Both children with SDNS and those with SRNS were characterized by increased tubular injury marker levels. 2. Patients with SRNS and higher proteinuria are more susceptible to early kidney damage.

Urinary Neutrophil Gelatinase-Associated Lipocalin to Monitor Lupus Nephritis Disease Activity

BACKGROUND

This study was conducted to determine whether there is an association between urinary neutrophil gelatinase-associated lipocalin (uNGAL) and urinary transforming growth factor-β1 (uTGF-β1) with lupus nephritis (LN) disease activity.

METHODS

Urine samples from 18 LN patients were collected every month for six months then examined for uNGAL, uTGF-β1, and renal domain Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score.

RESULTS

The uNGAL levels were significantly different between active and inactive LN (P < 0.05). uTGF-β1 levels were not different between active and inactive LN (P < 0.05). There was a significant correlation between uNGAL levels and renal domain SLEDAI score (r = 0.417, P < 0.05). There was no correlation between uTGF-β1 levels and renal domain SLEDAI score (r = 0.031, P < 0.05).

CONCLUSION

uNGAL is better than uTGF-β1 for differentiation of active and inactive LN. uNGAL can be considered as a biomarker to monitor LN disease activity.

Urine neutrophil gelatinase-associated lipocalin in asphyxiated neonates: a prospective cohort study

BACKGROUND

Acute kidney injury (AKI) is the most common complication of perinatal asphyxia. Recent research indicates that urine neutrophil gelatinase-associated lipocalin (NGAL) is an early marker for AKI; yet, there is a paucity of data about its use in term neonates with perinatal asphyxia.

METHODS

A prospective cohort study was conducted on 108 term babies in the new-born unit of Pumwani Maternity Hospital and Kenyatta National Hospital. Urine NGAL and serum creatinine were measured in 108 term asphyxiated neonates on days 1 and 3 of life.

RESULTS

One-hundred and eight patients were recruited (male:female 1.4:1). At a cut-off of 250 ng/ml, urine NGAL had an acceptable discriminative capability of predicting AKI (area under the curve 0.724). The sensitivity, specificity, positive and negative predictive value and likelihood ratios were 88, 56, 30, 95%, 2 and 0.2 respectively. Urine NGAL levels were significantly higher in patients with AKI compared with those without AKI. An NGAL level greater than 250 ng/ml on day 1 was significantly associated with severe hypoxic ischaemic encephalopathy (HIE); odds ratio = 8.9 (95% CI 1.78-37.69) and mortality; odds ratio = 8.9 (95% CI 1.78-37.69).

CONCLUSION

Urine NGAL is a good screening test for the early diagnosis of AKI. It is also a predictor of mortality and severity of HIE in asphyxiated neonates.

The impact of fluid balance on diagnosis, staging and prediction of mortality in critically ill patients with acute kidney injury

BACKGROUND

Fluid accumulation may delay recognition of acute kidney injury (AKI) in intensive care unit (ICU) patients. This study aims to evaluate the impact of fluid balance on the incidence, time of AKI diagnosis and predictive performance for outcomes of critically ill patients.

METHODS

This study included a cohort of 7696 adult ICU patients at Mayo Clinic Hospital in year 2011 with at least one serum creatinine (SCr) measured in ICU. AKI was defined based on SCr criterion for stage I of KDIGO definition. The AKI incidence and predictive performance for 60-day mortality was compared before and after SCr adjustment for fluid balance.

RESULTS

AKI was detected in 1860 (24.2 %) before and 1947 (25.3 %) after fluid balance adjustment (P < 0.001). Patients with AKI both before and after SCr adjustment had significantly higher 60-day mortality in comparison with patients who did not develop AKI (OR 3.38; 95 % CI 2.84-4.02). The risk of 60-day mortality in patients who met AKI criteria after but not before SCr adjustment was significantly higher than patients without AKI (OR 2.00; 95 % CI 1.25-3.11). In contrast, the risk of 60-day mortality in patients who met AKI criteria before but not after SCr adjustment was similar to patients without AKI (OR 1.19; 95 % CI 0.48-2.50). The C-statistic for unadjusted and adjusted SCr to predict 60-day mortality were 0.68 and 0.70, respectively (P = 0.001).

CONCLUSION

Our study found that SCr adjustment for fluid balance could result in a more accurate detection of AKI cases. We suggest using fluid balance adjustment for volume overload critically ill patients.

Gremlin regulates renal inflammation via the vascular endothelial growth factor receptor 2 pathway

Inflammation is a main feature of progressive kidney disease. Gremlin binds to bone morphogenetic proteins (BMPs), acting as an antagonist and regulating nephrogenesis and fibrosis among other processes. Gremlin also binds to vascular endothelial growth factor receptor-2 (VEGFR2) in endothelial cells to induce angiogenesis. In renal cells, gremlin regulates proliferation and fibrosis, but there are no data about inflammatory-related events. We have investigated the direct effects of gremlin in the kidney, evaluating whether VEGFR2 is a functional gremlin receptor. Administration of recombinant gremlin to murine kidneys induced rapid and sustained activation of VEGFR2 signalling, located in proximal tubular epithelial cells. Gremlin bound to VEGFR2 in these cells in vitro, activating this signalling pathway independently of its action as an antagonist of BMPs. In vivo, gremlin caused early renal damage, characterized by activation of the nuclear factor (NF)-κB pathway linked to up-regulation of pro-inflammatory factors and infiltration of immune inflammatory cells. VEGFR2 blockade diminished gremlin-induced renal inflammatory responses. The link between gremlin/VEGFR2 and NF-κB/inflammation was confirmed in vitro. Gremlin overexpression was associated with VEGFR2 activation in human renal disease and in the unilateral ureteral obstruction experimental model, where VEGFR2 kinase inhibition diminished renal inflammation. Our data show that a gremlin/VEGFR2 axis participates in renal inflammation and could be a novel target for kidney disease.

TGF-Beta Blockade Increases Renal Inflammation Caused by the C-Terminal Module of the CCN2

The CCN family member 2 (CCN2, also known as connective tissue growth factor) may behave as a risk biomarker and a potential therapeutic target for renal disease. CCN2 participates in the regulation of inflammation and fibrosis. TGF-β is considered the main fibrogenic cytokine; however, in some pathological settings TGF-β also has anti-inflammatory properties. CCN2 has been proposed as a downstream profibrotic mediator of TGF-β, but data on TGF-β role in CCN2 actions are scarce. Our aim was to evaluate the effect of TGF-β blockade in CCN2-mediated experimental renal damage. Systemic administration of the C-terminal module of CCN2 to mice caused sustained renal inflammation. In these mice, TGF-β blockade, using an anti-TGF-β neutralizing antibody, significantly increased renal expression of the NGAL (a kidney injury biomarker), kidney infiltration by monocytes/macrophages, and upregulation of MCP-1 expression. The anti-inflammatory effect of TGF-β seems to be mediated by a dysregulation of the systemic Treg immune response, shown by decreased levels of circulating CD4⁺/Foxp3⁺Treg cells. Our experimental data support the idea that TGF-β exerts anti-inflammatory actions in the kidney and suggest that it is not an optimal therapeutic target.

Plasma neutrophil gelatinase-associated lipocalin as a potential predictor of adverse renal outcomes in immunoglobulin A nephropathy

BACKGROUND/AIMS

Neutrophil gelatinase-associated lipocalin (NGAL) is a well-known biomarker of acute kidney injury. We evaluated the value of plasma NGAL (pNGAL) as an independent predictor of prognosis in immunoglobulin A nephropathy (IgAN).

METHODS

In total, 91 patients with biopsy-proven IgAN at a single center were evaluated. pNGAL was measured using a commercial enzyme-linked immunosorbent assay kit (R&D Systems). Adverse renal outcome was defined as chronic kidney disease (CKD) stage 3 or above at the last follow-up. Pearson correlation coefficient and Cox regression were used for analyses.

RESULTS

The mean age of all patients (male:female, 48:43) was 35 years (range, 18 to 77). pNGAL ranged between 21.68 and 446.40 ng/mL (median, 123.97) and showed a correlation with age (r = 0.332, p = 0.001), creatinine (r = 0.336, p = 0.001), estimated glomerular filtration rate (r = -0.397, p < 0.001), uric acid (r = 0.289, p = 0.006), and the protein-to-creatinine ratio (r = 0.288, p = 0.006). During a mean follow-up period of 37.6 months, 11 patients (12.1%) had CKD stage 3 or above. In a multivariate Cox regression model, hypertension (hazard ratio [HR], 8.779; 95% confidence interval [CI], 1.526 to 50.496; p = 0.015), proteinuria > 1 g/day (HR, 5.184; 95% CI, 1.124 to 23.921; p = 0.035), and pNGAL (HR, 1.012; 95% CI, 1.003 to 1.022; p = 0.013) were independent predictors associated with adverse renal outcome.

CONCLUSIONS

pNGAL showed strong correlations with other clinical prognostic factors and was also an independent predictor of adverse renal outcome. We suggest pNGAL as a potential predictor for prognosis in IgAN, while further studies are needed to confirm the clinical value.

Matrix metalloproteinases in inflammatory bowel disease: an update

Matrix metalloproteinases (MMPs) are known to be upregulated in inflammatory bowel disease (IBD) and other inflammatory conditions, but while their involvement is clear, their role in many settings has yet to be determined. Studies of the involvement of MMPs in IBD since 2006 have revealed an array of immune and stromal cells which release the proteases in response to inflammatory cytokines and growth factors. Through digestion of the extracellular matrix and cleavage of bioactive proteins, a huge diversity of roles have been revealed for the MMPs in IBD, where they have been shown to regulate epithelial barrier function, immune response, angiogenesis, fibrosis, and wound healing. For this reason, MMPs have been recognised as potential biomarkers for disease activity in IBD and inhibition remains a huge area of interest. This review describes new roles of MMPs in the pathophysiology of IBD and suggests future directions for the development of treatment strategies in this condition.

Whole blood neutrophil gelatinase-associated lipocalin predicts acute kidney injury in burn patients

BACKGROUND

Early detection of acute kidney injury (AKI) in severely burn-injured patients can help alter treatment to prevent progression to acute failure and reduce the need for renal replacement therapy. We hypothesized that whole blood neutrophil gelatinase-associated lipocalin (NGAL) will be increased in severely burn-injured patients who develop AKI during acute resuscitation.

MATERIALS AND METHODS

We performed a prospective observation study of adult burn patients with a 20% total body surface area (TBSA) burned or greater burn injury. Two-hour serial measurements of NGAL, serum creatinine (Cr), and hourly urine output (UO) were collected for 48 h after admission. Our primary goal was to correlate the risk of AKI in the first week after burn injury with serial NGAL levels in the first 48 h after admission. Our secondary goal was to determine if NGAL was an earlier independent predictor of AKI compared with Cr and UO.

RESULTS

We enrolled 30 adult (age ≥ 18 y) burn patients with the mean ± standard deviation age of 40.9 ± 15.4 and mean TBSA of 46.4 ± 22.4. Fourteen patients developed AKI within the first 7 d after burn injury. There were no differences in age, TBSA, fluid administration, mean arterial pressure, UO, and Cr between AKI and no-AKI patients. NGAL was significantly increased as early as 4 h after injury (182.67 ± 83.3 versus 107.37 ± 46.15) in the AKI group. Controlling for age, TBSA, and inhalation injury, NGAL was a predictor of AKI at 4 h after injury (odds ratio, 1.02) and remained predictive of AKI for the period of more than the first 24 h after admission. UO and Cr were not predictive of AKI in the first 24 h after admission.

CONCLUSIONS

Whole blood NGAL is markedly increased in burn patients who develop AKI in the first week after injury. In addition, NGAL is an early independent predictor of AKI during acute resuscitation for severe burn injury. UO and Cr are not predictive of AKI during this time period.

Clinical significance of neutrophil gelatinase-associated lipocalin in Crimean-Congo hemorrhagic Fever

Neutrophil gelatinase-associated lipocalin (NGAL), which is an important prognostic marker for sepsis and inflammatory diseases, is mostly released from neutrophils. Crimean-Congo hemorrhagic fever (CCHF) patients are generally neutropenic. We aimed to investigate whether there is a change in serum NGAL level and to investigate its effect on the recovery time (RT) during the course of CCHF. A total of 40 CCHF patients (19 females and 21 males) and 34 healthy controls (17 females and 17 males) were included in the study. The serum NGAL level and biochemical and hematological parameters were checked. The NGAL level of CCHF patients was significantly higher than that of the healthy controls (P < 0.001). A multivariate analysis showed that the independent prognostic factor for the prediction of the RT is the NGAL level (odds ratio [OR] 0.3, 95% confidence interval [Cl] 0.1-0.4, P < 0.001). An elevated NGAL level was found to be associated with an increased RT in CCHF patients. The NGAL levels of CHHF patients might be elevated due to increased cytokine release, the presence of a tissue injury, and the release of immature neutrophils from the bone marrow into the peripheral stream. This may be a good prognostic factor in CHHF patients.

Clinical significance of neutrophil gelatinase-associated lipocalin in Crimean-Congo hemorrhagic Fever

Neutrophil gelatinase-associated lipocalin (NGAL), which is an important prognostic marker for sepsis and inflammatory diseases, is mostly released from neutrophils. Crimean-Congo hemorrhagic fever (CCHF) patients are generally neutropenic. We aimed to investigate whether there is a change in serum NGAL level and to investigate its effect on the recovery time (RT) during the course of CCHF. A total of 40 CCHF patients (19 females and 21 males) and 34 healthy controls (17 females and 17 males) were included in the study. The serum NGAL level and biochemical and hematological parameters were checked. The NGAL level of CCHF patients was significantly higher than that of the healthy controls (P < 0.001). A multivariate analysis showed that the independent prognostic factor for the prediction of the RT is the NGAL level (odds ratio [OR] 0.3, 95% confidence interval [Cl] 0.1-0.4, P < 0.001). An elevated NGAL level was found to be associated with an increased RT in CCHF patients. The NGAL levels of CHHF patients might be elevated due to increased cytokine release, the presence of a tissue injury, and the release of immature neutrophils from the bone marrow into the peripheral stream. This may be a good prognostic factor in CHHF patients.

Perfusion index derived from a pulse oximeter can detect changes in peripheral microcirculation during uretero-renal-scopy stone manipulation (URS-SM)

Background

The objective of this study was to test the effect of removal of a ureteral obstruction (renal calculus) from anesthetized patients on the perfusion index (PI), as measured by a pulse oximeter, and on the estimated glomerular filtration rate (eGFR).

Patients and Methods

This prospective study enrolled 113 patients with unilateral ureteral obstructions (kidney stones) who were scheduled for ureteroscopy (URS) laser lithotripsy. One urologist graded patient hydronephrosis before surgery. A pulse oximeter was affixed to each patient's index finger ipsilateral to the intravenous catheter, and a non-invasive blood pressure cuff was placed on the contralateral side. Ipsilateral double J stents and Foley catheters were inserted and left indwelling for 24 h. PI and mean arterial pressure (MAP) were determined at baseline, 5 min after anesthesia, and 10 min after surgery; eGFR was determined at admission, 1 day after surgery, and 14 days after surgery.

Results

Patients with different grades of hydronephrosis had similar age, eGFR, PI, mean arterial pressure (MAP), and heart rate (HR). PI increased significantly in each hydronephrosis group after ureteral stone disintegration. None of the groups had significant post-URS changes in eGFR, although eGFR increased in the grade I hydronephrosis group after 14 days. The percent change of PI correlates significantly with the percent change of MAP, but not with that of eGFR.

Conclusion

Our results demonstrate that release of a ureteral obstruction leads to a concurrent increase of PI during anesthesia. Measurement of PI may be a valuable tool to monitor the successful release of ureteral obstructions and changes of microcirculation during surgery. There were also increases in eGFR after 14 days, but not immediately after surgery.

Neutrophil gelatinase-associated lipocalin as a marker of acute renal disease

PURPOSE OF REVIEW

Acute renal disease has major prognostic impact in hospitalized patients. Early diagnosis using renal function markers such as serum creatinine or urinary output and effective treatment are currently not possible. This review focuses on recent studies examining the biological characteristics and the diagnostic and prognostic value of a novel biomarker, neutrophil gelatinase-associated lipocalin (NGAL), in patients at risk for acute renal disease.

RECENT FINDINGS

NGAL levels increase early and proportional to the degree of renal injury in the urine and plasma. Here, we report the results of clinical studies where NGAL was measured in 325 patients with autoimmune and infectious diseases, those with cisplatin-associated nephrotoxicity, and more than 4000 patients at risk of acute kidney injury due to sepsis, cardiac surgery, exposure to contrast media, or after renal transplantation. Whenever renal damage occurred, as evidenced by histopathology or subsequent increase in serum creatinine levels, NGAL levels were higher than in patients without acute renal disease. An increase in NGAL substantially preceded clinical diagnosis of acute renal disease.

SUMMARY

NGAL fulfills many characteristics of an appropriate 'real-time' renal biomarker. The data on NGAL could justify re-assessment of the concept and definition of acute kidney injury.

The role of drug transporters in the kidney: lessons from tenofovir

Tenofovir disoproxil fumarate, the prodrug of nucleotide reverse transcriptase inhibitor tenofovir, shows high efficacy and relatively low toxicity in HIV patients. However, long-term kidney toxicity is now acknowledged as a modest but significant risk for tenofovir-containing regimens, and continuous use of tenofovir in HIV therapy is currently under question by practitioners and researchers. Co-morbidities (hepatitis C, diabetes), low body weight, older age, concomitant administration of potentially nephrotoxic drugs, low CD4 count, and duration of therapy are all risk factors associated with tenofovir-associated tubular dysfunction. Tenofovir is predominantly eliminated via the proximal tubules of the kidney, therefore drug transporters expressed in renal proximal tubule cells are believed to influence tenofovir plasma concentration and toxicity in the kidney. We review here the current evidence that the actions, pharmacogenetics, and drug interactions of drug transporters are relevant factors for tenofovir-associated tubular dysfunction. The use of creatinine and novel biomarkers for kidney damage, and the role that drug transporters play in biomarker disposition, are discussed. The lessons learnt from investigating the role of transporters in tenofovir kidney elimination and toxicity can be utilized for future drug development and clinical management programs.

Hypertension and hyperglycemia synergize to cause incipient renal tubular alterations resulting in increased NGAL urinary excretion in rats

Background

Hypertension and diabetes are the two leading causes of chronic kidney disease (CKD) eventually leading to end stage renal disease (ESRD) and the need of renal replacement therapy. Mortality among CKD and ESRD patients is high, mostly due to cardiovascular events. New early markers of risk are necessary to better anticipate the course of the disease, to detect the renal affection of additive risk factors, and to appropriately handle patients in a pre-emptive and personalized manner.

Methods

Renal function and NGAL urinary excretion was monitored in rats with spontaneous (SHR) or L-NAME induced hypertension rendered hyperglycemic (or not as controls).

Results

Combination of hypertension and hyperglycemia (but not each of these factors independently) causes an increased urinary excretion of neutrophil gelatinase-associated lipocalin (NGAL) in the rat, in the absence of signs of renal damage. Increased NGAL excretion is observed in diabetic animals with two independent models of hypertension. Elevated urinary NGAL results from a specific alteration in its tubular handling, rather than from an increase in its renal expression. In fact, when kidneys of hyperglycaemic-hypertensive rats are perfused in situ with Krebs-dextran solution containing exogenous NGAL, they excrete more NGAL in the urine than hypertensive rats. We also show that albuminuria is not capable of detecting the additive effect posed by the coexistence of these two risk factors.

Conclusions

Our results suggest that accumulation of hypertension and hyperglycemia induces an incipient and quite specific alteration in the tubular handling of NGAL resulting in its increased urinary excretion.

Importance of neutrophil gelatinase-associated lipocalin in differential diagnosis of acute and chronic renal failure

Background:

Neutrophil Gelatinase-associated Lipocalin (NGAL) protein is easily detected in the blood and urine soon after acute renal injury. NGAL gains features of an early, sensitive and noninvasive biomarker for acute renal injury. Recent evidences suggest that its expression is also increased in CRF reflecting the severity of disease.

Objectives:

In the present study, we aimed to investigate whether blood NGAL level plays a role in the differential diagnosis of acute and chronic renal failure.

Patients and Methods:

This was a prospective case-control study. Fifty patients presented to emergency department with acute renal failure (ARF), 30 with chronic renal failure (CRF) and 20 healthy individuals as control group were included in this study. Blood pH, HCO3^-, BUN, creatinine and potassium values were evaluated in all patients. Blood NGAL values were evaluated in all groups. BUN, serum creatinine and NGAL values were statistically compared between patients and controls.

Results:

Median NGAL levels in patients was 304.50 (29), and 60 (0) in control, which was statistically significant between the two groups (Z = -6.477, P < 0.001). The median NGAL values were 261.50 ± 291 in ARF group and 428.50 ± 294 in CRF group. There was a significant difference in NGAL level between ARF and CRF groups (Z = -2.52, P = 0.012). Median BUN values were 153.46 ± 82.47 in ARF group and 169.40 ± 93.94 in CRF group. There was no significant difference in BUN value between ARF and CRF groups (P > 0.05). Median creatinine values were 2.84 ± 2.95 in ARF group and 4.78 ± 4.32 in CRF group. In serum creatinine values, a significant difference was found between ARF and CRF groups (P < 0.05).

Conclusions:

Serum NGAL levels of ARF and CRF patients were significantly higher than healthy individuals. In addition, NGAL values of patients with CRF were significantly higher than those of ARF. Serum NGAL values can be used to detect renal injury and differentiate ARF and CRF.

Cilostazol renoprotective effect: modulation of PPAR-γ, NGAL, KIM-1 and IL-18 underlies its novel effect in a model of ischemia-reperfusion

Cilostazol, a phosphodiesterase-III inhibitor, reportedly exhibits positive effects against ischemia/reperfusion (I/R)-induced injury in several models. However, its potential role against the renal I/R insult has not been elucidated. To test whether the PPAR-γ (of peroxisome proliferator activated receptor gamma) pathway is involved in the cilostazol effect, rats were randomized into sham, I/R, cilostazol (50 and 100 mg/kg per day, orally), pioglitazone (3 and 10 mg/kg per day, orally) and their combination at the low dose levels. Drugs regimens were administered for 14 days prior to the I/R induction. Pretreatment with cilostazol or pioglitazone provided significant protection against the I/R-induced renal injury as manifested by the attenuated serum levels of creatinine, blood urea nitrogen and cystatin C. Both drugs have also opposed the I/R-induced elevation in tissue contents/activity of neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (Κim-1), nuclear factor-κB, interleuκin-18, caspase-1, as well as malondialdehyde, iNOS, myeloperoxidase, ICAM-1 and VCAM-1. Nevertheless, the drugs increased both the PPAR-γ transcriptional activity and the content of glutathione. Furthermore, combining the two low doses of both drugs produced effects comparable to that of the high dose level of either drug, advocating the fortification of pioglitazone renoprotective effect when given concomitantly with cilostazol. In conclusion, cilostazol purveyed conceivable novel renoprotective mechanisms and alleviated incidents associated with acute renal injury either alone or in combination with pioglitazone partially via the elevation of PPAR-γ besides the amendment of the aforementioned biomarkers.

Integrin-linked kinase plays a key role in the regulation of angiotensin II-induced renal inflammation

ILK (integrin-linked kinase) is an intracellular serine/threonine kinase involved in cell-matrix interactions. ILK dysregulation has been described in chronic renal disease and modulates podocyte function and fibrosis, whereas data about its role in inflammation are scarce. AngII (angiotensin II) is a pro-inflammatory cytokine that promotes renal inflammation. AngII blockers are renoprotective and down-regulate ILK in experimental kidney disease, but the involvement of ILK in the actions of AngII in the kidney has not been addressed. Therefore we have investigated whether ILK signalling modulates the kidney response to systemic AngII infusion in wild-type and ILK-conditional knockout mice. In wild-type mice, AngII induced an inflammatory response, characterized by infiltration of monocytes/macrophages and lymphocytes, and up-regulation of pro-inflammatory factors (chemokines, adhesion molecules and cytokines). AngII activated several intracellular signalling mechanisms, such as the NF-κB (nuclear factor κB) transcription factor, Akt and production of ROS (reactive oxygen species). All these responses were prevented in AngII-infused ILK-deficient mice. In vitro studies characterized further the mechanisms regulating the inflammatory response modulated by ILK. In cultured tubular epithelial cells ILK blockade, by siRNA, inhibited AngII-induced NF-κB subunit p65 phosphorylation and its nuclear translocation. Moreover, ILK gene silencing prevented NF-κB-related pro-inflammatory gene up-regulation. The results of the present study demonstrate that ILK plays a key role in the regulation of renal inflammation by modulating the canonical NF-κB pathway, and suggest a potential therapeutic target for inflammatory renal diseases.

Neutrophil gelatinase-associated lipocalin as a biomarker of acute kidney injury: a critical evaluation of current status

BACKGROUND

The early prediction of acute kidney injury (AKI) by current clinical and laboratory methods remains inadequate. Neutrophil gelatinase-associated lipocalin (NGAL) has emerged as a promising non-invasive biomarker of kidney injury. We systematically reviewed the utility of plasma and urine NGAL measurements for the prediction of AKI in humans.

METHODS

We searched MEDLINE, PubMed and EMBASE for human biomarker studies that included NGAL (January 2005 to October 2013). Studies reporting on the use of NGAL for the early prediction and prognosis of AKI were analysed in three common clinical settings: cardiac surgery, critical illness and kidney transplantation.

RESULTS

We identified 58 manuscripts that met our inclusion and exclusion criteria, reporting on more than 16,500 patients. Following cardiac surgery, NGAL measurement in over 7000 patients was predictive of AKI and its severity, with an overall area under the receiver operator characteristic curve (AUC) of 0.82-0.83. Similar results were obtained in over 8500 critically ill patients. In over 1000 patients undergoing kidney transplantation, NGAL measurements predicted delayed graft function with an overall AUC of 0.87. In all three settings, NGAL significantly improved the prediction of AKI risk over the clinical model alone.

CONCLUSIONS

We identified several studies that collectively strongly support the use of NGAL as a biomarker for the prediction of AKI. However, we noted some limitations, including lack of published studies that adhere to diagnostic study guidelines, heterogeneity in AKI definition, the lack of uniformly applicable cut-off values and variability in the performance of commercially available NGAL assays.

Circulating level of lipocalin 2 as a predictor of severity in patients with community-acquired pneumonia

BACKGROUND

The aim of this study was to investigate the differential plasma levels of lipocalin 2 (LCN2) and its complex with MMP-9 (where MMP is matrix metalloproteinase) before and after antibiotic treatment in hospitalized adult patients with community-acquired pneumonia (CAP).

METHOD

Plasma LCN2 and LCN2/MMP-9 complex levels were measured in 61 adult patients with CAP and 60 healthy controls using commercial enzyme-linked immunosorbent assay (ELISA).

RESULTS

A decrease in the number of white blood cells (WBCs) and neutrophils and decreases in the levels of C-reactive protein (CRP), LCN2, and LCN2/MMP-9 complex were observed after antibiotic treatment. The plasma level of LCN2, but not that of CRP, was correlated with the severity of CAP based on the Pneumonia Severity Index (PSI; r = 0.333, P = 0.009), confusion, urea, respiratory rate and blood pressure (CURB)-65 (r = 0.288, P = 0.024), and Acute Physiology And Chronic Health Evaluation II (APACHE II) scores (r = 0.328, P = 0.010). LCN2 levels were also significantly correlated with LCN2/MMP-9 levels and the numbers of WBCs or neutrophils.

CONCLUSIONS

Plasma levels of LCN2 and the LCN2/MMP-9 complex can act as adjuvant diagnostic biomarkers for CAP. Plasma LCN2 might play a further role in the clinical assessment of the severity of CAP, which could potentially guide the development of future treatment strategies.

Do neutrophil gelatinase-associated lipocalin and interleukin-18 predict renal dysfunction in patients with familial Mediterranean fever and amyloidosis?

BACKGROUND

The aim of this study was to evaluate whether neutrophil gelatinase-associated lipocalin (NGAL) and interleukin-18 (IL-18) predict renal disfunction in patients with familial Mediterranean fever (FMF).

METHODS

This prospective study consisted of 102 patients with FMF in attack-free period, and 40 matched healthy controls. Of the patients, nine were diagnosed as amyloidosis. The patients were divided into two groups according to eGFR as below 120 mL per minute and above 120 mL per minute. Also, patients were divided into three groups according to the degree of urinary albumin excretion as normoalbuminuric, microalbuminuric, and macroalbuminuric. The serum levels of IL-18 (sIL-18) and NGAL (sNGAL), and urinary levels of IL-18 (uIL-18) and NGAL (uNGAL) were measured by using ELISA kits.

RESULTS

The levels of sIL-18, sNGAL, uIL-18, and uNGAL were detected significantly higher in FMF patients, particularly in patients with amyloidosis, when compared to controls. sNGAL, uIL-18, and uNGAL were significantly higher in patients with eGFR < 120 mL per minute than in patients with eGFR ≥ 120 mL per minute. sNGAL, uIL-18, and uNGAL were correlated significantly with urinary albumin excretion, additionally, were inverse correlated with eGFR. The most remarkable findings of this study are of the higher values of sIL-18, sNGAL, uIL-18, and uNGAL in both normoalbuminuric FMF patients and patients with eGFR ≥ 120 mL per minute.

CONCLUSIONS

The results of this study suggest that sIL-18, uIL-18, sNGAL, and uNGAL are reliable markers of early renal disfunction in FMF patients, and may let us take measures from the early stage of renal involvement.

Biomarkers in the assessment of acute and chronic kidney diseases in the dog and cat

In both human and veterinary medicine, diagnosing and staging renal disease can be difficult. Measurement of glomerular filtration rate is considered the gold standard for assessing renal function but methods for its assessment can be technically challenging and impractical. The main parameters used to diagnose acute and chronic kidney disease include circulating creatinine and urea concentrations, and urine-specific gravity. However, these parameters can be insensitive. Therefore, there is a need for better methods to diagnose and monitor patients with renal disease. The use of renal biomarkers is increasing in human and veterinary medicine for the diagnosis and monitoring of acute and chronic kidney diseases. An ideal biomarker would identify site and severity of injury, and correlate with renal function, among other qualities. This article will review the advantages and limitations of renal biomarkers that have been used in dogs and cats, as well as some markers used in humans that may be adapted for veterinary use. In the future, measuring a combination of biomarkers will likely be a useful approach in the diagnosis of kidney disorders.

Neutrophil gelatinase-associated lipocalin

PURPOSE OF REVIEW

Acute kidney injury (AKI) is a major clinical problem in hospitalized patients. Effective treatment and early diagnosis of this syndrome are not currently available. This review focuses on recent studies examining the biological characteristics and the diagnostic and prognostic value of a novel biomarker--neutrophil gelatinase-associated lipocalin (NGAL)--in the two major patient populations at risk for AKI.

RECENT FINDINGS

NGAL is one of the most intensively investigated novel renal biomarkers with promising data from animal experiments and clinical studies comprising more than 3500 cardiac surgery or critically ill patients. NGAL was discovered using unbiased transcriptomic approaches and was identified as the gene with the earliest and highest rise of mRNA and protein concentration in renal tissue, urine and plasma following various renal insults. Within minutes to a few hours after a renal insult, NGAL is induced in and released from the injured distal nephron. The average sensitivity and specificity of NGAL--measured 1-3 days prior to current AKI consensus diagnosis--was 76 and 77% respectively for cardiac surgery patients and 73 and 80% respectively for patients admitted to the intensive care unit.

SUMMARY

NGAL appears to fulfill many characteristics of an appropriate 'real-time' biomarker for AKI detection.

Neutrophil gelatinase associated lipocalin as an indicator of acute kidney injury and inflammation in burned children

INTRODUCTION

Neutrophil gelatinase associated lipocalin (NGAL) is a novel predictor of acute kidney injury (AKI), which increases with inflammation. We aimed to assess whether serum NGAL (SNGAL) and urine NGAL (UNGAL) can predict AKI in burned children.

METHODS

Patients were referred within the 12 h of burn to our center. Serum samples for SNGAL, C-reactive protein (CRP), procalcitonin (PCT) and urine for UNGAL, microalbumine (Umalb), creatinine (Ucr) were obtained at both admission and the 5th day after burn. Blood urea nitrogen (BUN) and serum creatinine (Scr) were examined daily.

RESULTS

Twenty-two subjects were enrolled and six (27.2%) of them developed AKI within the 48 h of injury. Burn size and abbreviated burn severity index (ABSI) were significantly increased in patients with AKI. CRP, PCT, SNGAL and UNGAL levels at admission and day 5 were significantly higher in patients with AKI than in those without AKI and controls. Scr was not significant between AKI and non-AKI groups at hospital days 1 and 5. A SNGAL level of 315 ng/ml and a UNGAL level of 100 ng/ml were determined as predictive cut-off values of AKI at admission (sensitivity and specificity: 71.4%, 83.3% and 93.3%, 93.7%, respectively). SNGAL and UNGAL were positively correlated with CRP, PCT, ABSI and Umalb/Ucr.

CONCLUSION

SNGAL and UNGAL are good early predictors of AKI in children with severe burn. NGAL might reflect the severity of burn insult and also could be used as an indicator of inflammation in burn children.

Elevation of neutrophil gelatinase-associated lipocalin (NGAL) in non-azotemic dogs with urinary tract infection

Neutrophil gelatinase-associated lipocalin (NGAL) is a promising biomarker in humans and dogs with kidney disease. This protein is expressed by many cells including renal tubular cells and neutrophils. The aim of this study was to evaluate the effect of urinary tract infection (UTI) on urinary NGAL (uNGAL) concentration in dogs. Urine culture and measurement of uNGAL level were performed in 80 non-azotemic dogs suspected of UTI and 19 healthy dogs. Dogs were divided in three groups: 19 healthy dogs, 25 dogs with positive culture and 55 dogs suspected of UTI but with negative culture. uNGAL and uNGAL/Creatinine was significantly higher (P < 0.0001) in dogs with UTI (14.22 ng/mL;19.74 μg/g) compared to Healthy (0.24 ng/mL;0.11 μg/g) and Negative (1.13 ng/mL;1.28 μg/g) dogs. A uNGAL value <3.38 ng/mL had a negative predictive value for UTI of 87%. Presence of UTI has to be considered when uNGAL is used to detect kidney disease.

Association of urinary lipocalin-2 with lupus nephritis

OBJECTIVE(S)

Lupus nephritis (LN) is the main cause of mortality and disability in systemic lupus erythematosus (SLE) patients. Therefore, utilizing a reliable and non-invasive method for serial measurements of renal function seems to be necessary. The aim of this study was to evaluate the role of urinary lipocalin-2 as a biomarker of renal involvement in SLE patients.

MATERIALS AND METHODS

Fifty two lupus patients in this cross sectional study were divided into two groups: patients with and without nephritis. For each group, urinary lipocalin-2, values were measured and reported according to urinary lipocalin-2/creatinine. Urinary lipocalin-2/creatinine sensitivity and specificity for identifying biopsy-proven nephritis were calculated, and a receiver operating characteristic (ROC) curve was constructed. Results : The mean urinary lipocalin-2/creatinine value of patients with biopsy-proven LN was 2.99 ± 4.1 ng/mg, and in non-LN patients was 1.16 ± 1.27 ng/mg. Urinary lipocalin-2/creatinine levels in LN patients were significantly higher than those in non-LN patients (P- Value = 0.03). In LN patients, urinary lipocalin-2/creatinine significantly correlated with proteinuria (r = 0.68; P = 0.0001). Using a cutoff value of 0.896 ng/mg, urinary lipocalin-2/creatinine had a sensitivity of 89.7% and a specificity of 39.1% for identifying SLE patients with biopsy-proven LN. The area under the ROC curve was 0.664 ± 0.076 with a 95% confidence interval of 0.52-0.81 (P=0.04). Analysis of variance showed that urinary lipocalin-2/creatinine is the same in different classes of LN (P-value=0.28).

CONCLUSION

An important clinical conclusion is that measurement of urinary Lipocalin-2 may result in earlier diagnosis of LN.

Urinary NGAL levels correlate with differential renal function in patients with ureteropelvic junction obstruction undergoing pyeloplasty

PURPOSE

Recent investigations described the use of NGAL, a sensitive biomarker for kidney injury, in the setting of ureteropelvic junction obstruction. We prospectively evaluated urinary NGAL levels in the affected renal pelvis and bladder of children with ureteropelvic junction obstruction undergoing unilateral dismembered pyeloplasty. Our hypothesis was that higher NGAL in the kidney and bladder would correlate with decreased ipsilateral differential function.

MATERIALS AND METHODS

We performed a prospective cohort study in patients treated with unilateral dismembered pyeloplasty from 2010 to 2012. Urine was obtained intraoperatively from the bladder and obstructed renal pelvis. A control population of unaffected children was recruited to provide a voided bladder specimen. Bladder NGAL levels were compared between the study and control populations. We tested our study hypothesis by correlating bladder and renal pelvic NGAL levels with the differential renal function of the affected kidney.

RESULTS

A total of 61 patients with a median age at surgery of 1.62 years (range 0.12 to 18.7) were enrolled in the study. Median bladder NGAL was 18.6 ng/mg (range 1.4-1,650.8) and median renal pelvic NGAL was 26.2 ng/mg (range 1.2-18,034.5, p = 0.004). Median bladder NGAL was significantly higher than in controls (p = 0.004). The correlation of bladder and renal pelvic NGAL with differential renal function was r = -0.359 (p = 0.004) and r = -0.383 (p = 0.002), respectively.

CONCLUSIONS

Bladder NGAL is increased in children with ureteropelvic junction obstruction. Renal pelvic and bladder normalized urinary NGAL levels correlate inversely with the relative function of the affected kidney in cases of unilateral ureteropelvic junction obstruction.

Plasma neutrophil gelatinase-associated lipocalin as a biomarker for acute kidney injury in critically ill patients with suspected sepsis

OBJECTIVES

The aim of this study was to investigate the diagnostic utility of plasma neutrophil gelatinase-associated lipocalin (NGAL) as an early objective biomarker to predict acute kidney injury (AKI) in critically ill patients with suspected sepsis, for whom procalcitonin (PCT) was used for the diagnosis and staging of sepsis.

DESIGN AND METHODS

Plasma NGAL was measured using the Triage NGAL Test (Alere, Inc., San Diego, CA, USA) in 231 samples obtained from patients with suspected sepsis. The results of NGAL were compared with those of Elecsys BRAHMS PCT (Roche Diagnostics, Basel, Switzerland). Renal failure was assessed using the renal subscore of Sepsis-related Organ Failure Assessment (SOFA) score. AKI was defined according to the Acute Kidney Injury Network criteria.

RESULTS

The concentrations of plasma NGAL were significantly different according to the five groups of PCT concentration (P<0.0001) and the renal subscore of SOFA score (P<0.0001). Plasma NGAL was significantly increased in the patients with AKI compared with those without AKI (416.5 ng/mL vs. 181.0 ng/mL, P=0.0223).

CONCLUSION

Plasma NGAL seems to be a highly sensitive and objective predictor of AKI in patients with sepsis. Plasma NGAL can be added for the diagnosis and staging of renal failure in sepsis.

Review and discussion of tubular biomarkers in the diagnosis and management of diabetic nephropathy

The prevalence of diabetic nephropathy has tremendously increased with the relentless rise in the incidence of diabetes over the last couple decades. Diabetic nephropathy is a leading cause of morbidity and mortality, and it invariably leads to an end-stage renal disease (ESRD). In an effort to delay the onset of ESRD systematic screening and appropriate management are needed to evaluate the progression of renal damage in diabetic nephropathy. The reliability of current tests in predicting the onset, progression and response to various regimens for diabetic nephropathy is still under debate; and it has engendered a search for more sensitive and specific urinary biomarkers, especially those reflective of tubular dysfunctions. It is well-known that there is a good correlation between the degree of damage to the tubulo-interstitial compartment and the deterioration of renal functions. In view of this, the utility of urinary biomarkers, reflective of tubular injury, reported in the literature is discussed in this brief review.

Heart failure biomarkers

Biomarker testing in patients with heart failure (HF) is rapidly expanding. With high-quality research indicating its diagnostic and prognostic capabilities, biomarkers are excellent adjuncts to manage patients with HF. Their superiority lies mainly in their reflection of ongoing pathophysiological events at a cellular level. Monitoring biomarker levels has been shown to provide incremental information on the progression of disease, thus allowing to better tailor treatment and management. Several biomarkers have gained attention in the past decade and continuing research demonstrates the specificity of each biomarker to be used on its own or in combination to improve diagnostic accuracy. This review will provide an insight into the role of such biomarkers, which are widely studied in the setting of HF so as to delineate their role in diagnosing, prognosticating, and titrating HF therapy.

A miniaturized immunoassay platform to measure neutrophil gelatinase-associated lipocalin (NGAL) for diagnosis of acute kidney injury

In this study, we describe the development and evaluation of a slide-based immunoassay platform for the detection of neutrophil gelatinase associated-lipocalin (NGAL) in plasma and urine samples. The capture NGAL antibody was immobilized onto a microscope slide before an analysis of NGAL based on a sandwich immunoassay was further carried out. This assay system exhibited linearity between 50 to 1000 ng/ml of NGAL. The coefficients of variability (CVs) indicated good reproducibility and repeatability of the system. The levels of plasma NGAL measured by the slide-based system were highly correlated with those of ELISA, while this system over-predicted urine NGAL.

Is serum cystatin C an early predictor for acute kidney injury following cardiopulmonary bypass surgery in infants and young children?

Acute kidney injury (AKI) is a potential complication following cardiopulmonary bypass (CPB) surgery in infants and young children with congenital heart disease (CHD). The current pilot study evaluates the predictive value of serum cystatin C (CysC) for AKI after pediatric CPB surgery. We prospectively enrolled 43 children with CHD (30 males and 13 females) who underwent CPB surgery. They were aged 3 years or younger. Serum CysC was measured at baseline and at 6 hours, 12 hours, 24 hours, and 48 hours after initiating CBP. Twenty-one (48.8%) patients developed AKI after cardiac surgery. Children who developed AKI had more complex cardiac surgical procedures (based on the Risk Adjustment for Congenital Heart Surgery 1 [RACHS-1] category), a longer CPB duration, and a longer aortic clamping time (ACT). Serum concentrations of CysC postoperatively demonstrated an initial decline at 6 hours, a subsequent increase at 12 hours, and stabilized at 24-48 hours. The best predictive performance was achieved 6 hours after CPB with an area under receiver operating characteristic curve (AUC) value of 0.69. The optimal cut-off value was 0.47 mg/L (sensitivity, 85.7%; specificity, 50%). By contrast, the RACHS-1 category, CPB duration, and ACT had higher AUC values at 0.735, 0.791, and 0.731, respectively. In conclusion, serum CysC had limited predictive capacity and was not superior to clinical risk factors for the early detection of AKI after CPB surgery in this pilot study, which focused on infants and young children.