Neutrophil gelatinase-associated lipocalin as the real-time indicator of active kidney damage

Implications of the changes in serum neutrophil gelatinase-associated lipocalin and cystatin C in patients with chronic kidney disease

AIM

Early intervention in patients with chronic kidney disease (CKD) significantly improves the prognosis. The present widely used markers of renal function, such as serum creatinine (sCr), fail to reflect early renal damage and predict the progression of disease. The authors aimed to evaluate whether neutrophil gelatinase-associated lipocalin (NGAL), a novel specific biomarker of acute kidney injury, could predict the progression of CKD.

METHODS

We identified 92 patients with stage 2-4 CKD caused by primary chronic glomerulonephritis. The patients were followed for 2 years, the changes in NGAL levels in the progressive and non-progressive groups were compared.

RESULTS

First, the serum NGAL levels of patients with stage 2-4 CKD were significantly increased compared with the control group. Second, based on Pearson correlation analysis, positive correlations existed between NGAL and cystatin C levels and between NGAL and sCr levels. Third, bounded by the progress of renal function, the area under the curve of serum NGAL was 0.872 (95% confidence interval, 0.786-0.933), which suggests a blood NGAL cut-off level of 246 ng/mL (sensitivity 85.19%, specificity 81.54%). Fourth, Kaplan-Meier survival curve analysis showed that the serum NGAL level was closely related to the end-point of renal function in patients with CKD. Fifth, Cox multivariate regression analysis showed that the estimated glomerular filtration rate and blood NGAL are associated with progression of CKD.

CONCLUSION

Serum NGAL is an effective biomarker for detecting early-stage renal damage in CKD patients. Serum NGAL was significantly correlated with the severity of renal damage and the progression of renal function deterioration.

Cardiovascular biomarkers in chronic kidney disease: state of current research and clinical applicability

The high incidence of cardiovascular events in chronic kidney disease (CKD) warrants an accurate evaluation of risk aimed at reducing the burden of disease and its consequences. The use of biomarkers to identify patients at high risk has been in use in the general population for several decades and has received mixed reactions in the medical community. Some practitioners have become staunch supporters and users while others doubt the utility of biomarkers and rarely measure them. In CKD patients numerous markers similar to those used in the general population and others more specific to the uremic population have emerged; however their utility for routine clinical application remains to be fully elucidated. The reproducibility and standardization of the serum assays are serious limitations to the broad implementation of these tests. The lack of focused research and validation in randomized trials rather than ad hoc measurement of multiple serum markers in observational studies is also cause for concern related to the clinical applicability of these markers. We review the current literature on biomarkers that may have a relevant role in field of nephrology.

Plasma neutrophil gelatinase-associated lipocalin and worsening renal function during everolimus therapy after heart transplantation

Recently, the mammalian target of rapamycin inhibitor everolimus (EVL) has been introduced as a novel immunosuppressant for heart transplant (HTx) recipients, and is expected to preserve renal function compared to conventional calcineurin inhibitors (CNIs). However, a considerable number of recipients treated with EVL were not free from worsening renal function regardless of CNI reduction. Data were collected retrospectively from 27 HTx recipients who had received EVL (trough concentration, 3.1-9.2 ng/mL) along with reduced CNIs (%decreases in trough concentration, 27.3 ± 13.0%) because of switching from mycophenolate mophetil due to digestive symptoms or neutropenia, progressive coronary artery vasculopathy, or persistent renal dysfunction, and had been followed over 1 year between August 2008 and January 2013. Estimated glomerular filtration rate (eGFR) decreased in 5 recipients (18.5%) during the study period. Univariate logistic regression analysis demonstrated that a higher plasma neutrophil gelatinase-associated lipocalin (P-NGAL) level was the only significant predictor for a decrease in eGFR over a 1-year EVL treatment period among all baseline parameters (P = 0.008). eGFR and proteinuria worsened almost exclusively in patients with baseline P-NGAL ≥ 85 ng/mL, which was the cutoff value calculated by an ROC analysis (area under the curve, 0.955; sensitivity, 1.000; specificity, 0.955). In conclusion, higher P-NGAL may be a novel predictor for the worsening of renal function after EVL treatment that is resistant to CNI reduction in HTx recipients.

Comparative assessment of neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C as early biomarkers for early detection of renal failure in patients with hypertension

BACKGROUND

Hypertension is one the most common causes of chronic kidney disease (CKD). One of the major concerns in hypertensive patients is early detection of renal disorders. In the past, serum creatinine (Scr) concentration was used as a marker of kidney function, but it proffers a late reflection of reduced glomerular filtration rate. Cystatin C and neutrophil gelatinase-associated lipocalin (NGAL) have been recently proven to be useful for quantification of CKD. Therefore, we compared the diagnostic value of NGAL with cystatin C and creatinine to evaluate kidney function in hypertensive patients.

METHODS

In this study, 42 hypertensive patients and 30 healthy volunteers were recruited. Serum cystatin C (Scys C) and plasma NGAL were measured using ELISA method. Creatinine, urea, hemoglobin, fibrinogen, and C-reactive protein were measured according to the routine methods. Estimated glomerular filtration rate (eGFR) was considered as the gold standard method (cut-off value of < 78 ml/min/1.73 m².

RESULTS

In the patient group, plasma NGAL, cystatin C, and creatinine were all significantly correlated with eGFR, and plasma NGAL correlated best with eGFR. Receiver-operating characteristics analysis indicated that plasma NGAL was a better indicator than creatinine and cystatin C for predicting a GFR < 78 ml/min/1.73 m2. The sensitivity and specificity for NGAL were 96% and 100%, for cystatin C were 92% and 60% and for creatinine were 76% and 47%, respectively.

CONCLUSION

Plasma NGAL demonstrated a higher diagnostic value to detect kidney impairment in the early stages of CKD as compared to Scys C and Scr in hypertensive patients.

Diagnostic and prognostic value of neutrophil gelatinase-associated lipocalin, matrix metalloproteinase-9, and tissue inhibitor of matrix metalloproteinases-1 for sepsis in the Emergency Department: an observational study

INTRODUCTION

The aim of this study was to evaluate the early diagnostic, risk stratification and prognostic value of neutrophil gelatinase-associated lipocalin (NGAL), matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of matrix metalloproteinases-1 (TIMP-1), compared with procalcitonin (PCT) and the Mortality in Emergency Department Sepsis (MEDS) score in septic patients in the emergency department (ED).

METHODS

In total, 480 consecutive adult patients were enrolled in this study. They fulfilled the systemic inflammatory response syndrome (SIRS) criteria and were admitted to the ED of Beijing Chaoyang Hospital from February 2013 to August 2013. A total of 40 healthy controls comprised the control group. The patients were classified into four groups: SIRS, sepsis, severe sepsis, and septic shock. Serum NGAL, MMP-9, TIMP-1 and PCT were measured, and MEDS score was calculated at enrollment. The prognostic values of NGAL, MMP-9 and TIMP-1 were compared with PCT and MEDS score. A 28-day follow-up was performed for all patients.

RESULTS

The median levels of serum NGAL and TIMP-1 increased with sepsis severity. The areas under the receiver operating characteristic (AUC) curves of NGAL or TIMP-1 were greater than those of PCT and MEDS score in diagnosing and predicting 28-day mortality, and the AUC of a combination of NGAL and MEDS score or TIMP-1 and MEDS score was more significant. Serum NGAL, MMP-9 and TIMP-1 levels were significantly higher in non-survivors than survivors at 28 days' follow-up. In addition, the level of NGAL was much higher in septic patients with acute kidney injury (AKI) than those without AKI. NGAL, TIMP-1, MMP-9 and MEDS score were found to be independent predictors of 28-day mortality in septic patients. The levels of serum NGAL and TIMP-1 were positively correlated with PCT and MEDS score in every septic group.

CONCLUSIONS

NGAL and TIMP-1 are valuable for the risk stratification, early diagnosis and prognostication of sepsis in the ED. NGAL is also a valuable biomarker for prognosis of septic patients with AKI in the ED.

Neutrophil gelatinase-associated lipocalin and liver-type fatty acid-binding protein as biomarkers for acute kidney injury after organ transplantation

PURPOSE

Neutrophil gelatinase-associated lipocalin (NGAL) and liver-type fatty acid-binding protein (L-FABP) are promising early biomarkers for acute kidney injury (AKI). In organ transplant recipients, AKI predictability based on NGAL and L-FABP remains to be elucidated. Furthermore, the association between serial NGAL and L-FABP measurements and AKI outcome is unknown. Therefore, we conducted a study to evaluate the ability of NGAL and L-FABP to predict AKI after organ transplantation and investigate the association between NGAL, L-FABP and AKI outcome.

METHODS

Twenty-five organ transplant recipients admitted to the intensive care unit (ICU) immediately after transplant surgery were studied prospectively. Plasma NGAL (P-NGAL), urinary NGAL (U-NGAL) and L-FABP were measured from ICU admission to ICU discharge. U-NGAL and L-FABP were corrected for dilution/concentration by calculating U-NGAL/urine creatinine ratios (U-NGAL/Cr) and L-FABP/urine creatinine ratios (L-FABP/Cr). AKI was defined according to the Kidney Disease: Improving Global Outcomes criteria.

RESULTS

AKI occurred in 11 patients. P-NGAL, U-NGAL/Cr and L-FABP/Cr upon ICU admission were unrelated to AKI development (p = 0.24, 0.22, and 0.53, respectively). There were no differences in P-NGAL, U-NGAL/Cr, and L-FABP/Cr levels from day 1 to day 6 between patients who did not recover from AKI and patients who recovered from AKI (p = 0.82, 0.26, and 0.61, respectively).

CONCLUSION

Our findings suggest that NGAL and L-FABP upon ICU admission are not predictive of AKI and serial NGAL and L-FABP measurements may be ineffective for monitoring the status and treatment of post-transplantation AKI.

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.

Evaluation of the optimal neutrophil gelatinase-associated lipocalin value as a screening biomarker for urinary tract infections in children

Background

Neutrophil gelatinase-associated lipocalin (NGAL) is a promising biomarker in the detection of kidney injury. Early diagnosis of urinary tract infection (UTI), one of the most common infections in children, is important in order to avert long-term consequences. We assessed whether serum NGAL (sNGAL) or urine NGAL (uNGAL) would be reliable markers of UTI and evaluated the appropriate diagnostic cutoff value for the screening of UTI in children.

Methods

A total of 812 urine specimens and 323 serum samples, collected from pediatric patients, were analyzed. UTI was diagnosed on the basis of culture results and symptoms reported by the patients. NGAL values were measured by using ELISA.

Results

NGAL values were more elevated in the UTI cases than in the non-UTI cases, but the difference between the values were not statistically significant (P=0.190 for sNGAL and P=0.064 for uNGAL). The optimal diagnostic cutoff values of sNGAL and uNGAL for UTI screening were 65.25 ng/mL and 5.75 ng/mL, respectively.

Conclusions

We suggest that it is not appropriate to use NGAL as a marker for early diagnosis of UTI in children.

Comparison of renal biomarkers with glomerular filtration rate in susceptibility to the detection of gentamicin-induced acute kidney injury in dogs

Fourteen renal biomarkers were compared with measurement of glomerular filtration rate (GFR) in detecting acute kidney injury (AKI) in beagle dogs given gentamicin (40 mg/kg/day by subcutaneous injection) for 7 consecutive days. Serum and urinary biomarkers were measured before administration of gentamicin and then on days 4 and 8 after starting administration. GFR was derived by use of a simplified equation. Increased urinary cystatin C and decreased GFR occurred from day 4 and were detected before increases in blood urea nitrogen (BUN) and serum creatinine concentrations and changes in other urinary parameters. The closest correlation was between urinary cystatin C and GFR. At termination, microscopical examination revealed extensive necrosis of proximal tubular epithelium with hyaline casts in the kidney of treated dogs. These data indicate that urinary cystatin C is the most sensitive index of kidney injury and GFR reflects the kidney functional mass.

Assessment of biochemical markers in the early post-burn period for predicting acute kidney injury and mortality in patients with major burn injury: comparison of serum creatinine, serum cystatin-C, plasma and urine neutrophil gelatinase-associated lipocalin

Introduction

The reported mortality rates range from 28% to 100% in burn patients who develop acute kidney injury (AKI) and from 50% to 100% among such patients treated with renal replacement therapy. Recently, the serum cystatin C and plasma and urine neutrophil gelatinase-associated lipocalin (NGAL) levels have been introduced as early biomarkers for AKI; the levels of these biomarkers are known to increase 24 to 48 hours before the serum creatinine levels increase. In this study, we aimed to estimate the diagnostic utility of the cystatin C and plasma and urine NGAL levels in the early post-burn period as biomarkers for predicting AKI and mortality in patients with major burn injuries.

Methods

From May 2011 to July 2012, 90 consecutive patients with a burn wound area comprising ≥ 20% of the total body surface area (TBSA) were enrolled in this study. Whole blood and urine samples were obtained for measuring the serum creatinine, serum cystatin C, and urine and plasma NGAL levels at 0, 3, 6, 12, 24, and 48 hours after admission. Receiver operating characteristic curve, area under the curve, and multivariate logistic regression analyses were performed to assess the predictive values of these biomarkers for AKI and mortality.

Results

In the multivariate logistic regression analysis, all variables, including age, percentage TBSA burned, sex, inhalation injury, and serum creatinine levels, serum cystatin C levels, and plasma and urine NGAL levels were independently associated with AKI development. Moreover, age, sex, percentage TBSA burned, and plasma and urine NGAL levels were independently associated with mortality. However, inhalation injury and the serum creatinine and cystatin C levels were not independently associated with mortality.

Conclusions

Massively burned patients who maintained high plasma and urine NGAL levels until 12 hours after admission were at the risk of developing early AKI and early mortality with burn shock. However, the plasma and urine NGAL levels in the early post-burn period failed to predict late AKI and non-burn shock mortality in this study. Nevertheless, the plasma and urine NGAL levels were independently associated with AKI development and mortality within 48 hours after admission.

Serum and urinary NGAL but not KIM-1 raises in human postrenal AKI

BACKGROUND

We examined the value of the novel acute kidney injury (AKI) markers neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) in acute postrenal impairment. These biomarkers have been evaluated in prerenal and intrarenal AKI so far, but not in human acute postrenal kidney injury. With regard to multimorbid and critically ill patients the discrimination of different AKI origins often remains a challenge. As the trend goes towards a diagnostic panel of AKI markers, we hereby aim to contribute to evaluate further options of discrimination in an observational case-control study.

MATERIALS AND METHODS

Blood and urine samples were obtained from 53 patients with acute obstructive nephropathy secondary to ureteral calculi and 52 age-matched healthy controls. Serum NGAL (sNGAL), urinary NGAL (uNGAL) and urinary KIM-1 (uKIM-1) levels were determined using a commercially available ELISA kit, creatinine applying the Jaffé's method.

RESULTS

While urinary levels of KIM-1 were not significantly different between patients with obstructive nephropathy and controls, a striking increase in sNGAL (P < 0·001) and uNGAL (P < 0·01) levels was detected in the obstructive nephropathy group. Within the obstructive nephropathy group, sNGAL (P = 0·01) and uNGAL (P = 0·049) but not uKIM-1 correlated positively with the white blood cell count and uNGAL correlated positively (P = 0·002) with the extent of leucocyturia.

CONCLUSIONS

High levels of sNGAL and uNGAL observed in stone-induced acute obstructive nephropathy may represent a valuable marker of postrenal AKI. Low uKIM-1 levels may help to discriminate postrenal AKI events using a panel of markers in this setting.

Involvement of neutrophil gelatinase-associated lipocalin and osteopontin in renal tubular regeneration and interstitial fibrosis after cisplatin-induced renal failure

The kidney has a capacity to recover from ischemic or toxic insults that result in cell death, and timely tissue repair of affected renal tubules may arrest progression of injury, leading to regression of injury and paving the way for recovery. To investigate the roles of neutrophil gelatinase-associated lipocalin (NGAL/lcn2) and osteopontin (OPN/spp1) during renal regeneration, the expression patterns of NGAL and OPN in the cisplatin-induced rat renal failure model were examined. NGAL expression was increased from day 1 after injection; it was seen mainly in the completely regenerating proximal tubules of the cortico-medullary junction on days 3-35; however, the expression was not seen in abnormally dilated or atrophied renal tubules surrounded by fibrotic lesions. On the other hand, OPN expression was increased from day 5 and the increased expression developed exclusively in the abnormal renal tubules. NGAL expression level well correlated with the proliferating activity in the regenerating renal epithelial cells, whereas OPN significantly correlated with the α-smooth muscle actin-positive myofibroblast appearance, expression of transforming growth factor (TGF)-β1, and the number of CD68-positive macrophages. Interestingly, rat renal epithelial cell line (NRK-52E) treated with TGF-β1 decreased NGAL expression, but increased OPN expression in a dose-dependent manner. Because increases of TGF-β1, myofibroblasts and macrophages contribute to progressive interstitial renal fibrosis, OPN may be involved in the pathogenesis of fibrosis; on the contrary, NGAL may play a role in tubular regeneration after injury. Expression analysis of NGAL and OPN would be useful to investigate the tubule damage in renal-toxicity.

Admission plasma neutrophil gelatinase associated lipocalin (NGAL) predicts worsening renal function during hospitalization and post discharge outcome in patients with acute heart failure

Abstract Background: The role of neutrophil gelatinase-associated lipocalin (NGAL) has been described in chronic heart failure (HF), however less data are available in patients admitted for acute HF.

METHODS

We evaluated the role of NGAL in predicting in-hospital worsening renal function (WRF) and post-discharge follow-up during six months period in patients with acute HF. All patients were submitted to creatinine, estimated glomerular filtration rate (eGFR), blood urea nitrogen (BUN) and B-type natriuretic peptide (BNP) measurement during hospitalization and before discharge.

RESULTS

Patients with chronic kidney dysfunction (CKD) demonstrated higher NGAL respect to subject with preserved renal function (241 ± 218 and 130 ± 80 ng/ml; P = 0.0001). In subgroup that developed WRF during hospitalization, NGAL levels were significantly increased respect to patients without WRF (272 ± 205 versus 136 ± 127 ng/ml; P = 0.0001). A cut off of 134 ng/ml has been related to WRF with good sensibility and specificity (92% and 71% AUC 0.83; P = 0.001). Multivariable Cox regression analysis showed that cut-off of 134 ng/ml was the only marker related to death (HR: 1.75; 95% CI: 1.24-2.45; P < 0.001). Follow-up analysis confirmed that NGAL > 130 ng/ml was associated with adverse events during a six-month period.

CONCLUSION

Admission NGAL measurement appears a sensible tool for in-hospital WRF prediction as well as an early marker for adverse outcome during post discharge vulnerable phase.

The early activation of toll-like receptor (TLR)-3 initiates kidney injury after ischemia and reperfusion

Acute kidney injury (AKI) is one of the most important complications in hospitalized patients and its pathomechanisms are not completely elucidated. We hypothesize that signaling via toll-like receptor (TLR)-3, a receptor that is activated upon binding of double-stranded nucleotides, might play a crucial role in the pathogenesis of AKI following ischemia and reperfusion (IR). Male adult C57Bl6 wild-type (wt) mice and TLR-3 knock-out (-/-) mice were subjected to 30 minutes bilateral selective clamping of the renal artery followed by reperfusion for 30 min 2.5h and 23.5 hours or subjected to sham procedures. TLR-3 down-stream signaling was activated already within 3 h of ischemia and reperfusion in post-ischemic kidneys of wt mice lead to impaired blood perfusion followed by a strong pro-inflammatory response with significant neutrophil invasion. In contrast, this effect was absent in TLR-3-/- mice. Moreover, the quick TLR-3 activation resulted in kidney damage that was histomorphologically associated with significantly increased apoptosis and necrosis rates in renal tubules of wt mice. This finding was confirmed by increased kidney injury marker NGAL in wt mice and a better preserved renal perfusion after IR in TLR-3-/- mice than wt mice. Overall, the absence of TLR-3 is associated with lower cumulative kidney damage and maintained renal blood perfusion within the first 24 hours of reperfusion. Thus, we conclude that TLR-3 seems to participate in the pathogenesis of early acute kidney injury.

An AKI biomarker lipocalin 2 in the blood derives from the kidney in renal injury but from neutrophils in normal and infected conditions

BACKGROUND

Lipocalin 2 (LCN2 or neutrophil gelatinase-associated lipocalin) is a secretory protein discovered from neutrophils, which accumulates in the blood and urine during acute kidney injury (AKI) and in the blood by bacterial infection. Little is known about the tissue source and molecular forms of this protein under normal and pathophysiologic conditions.

METHODS

By sandwich ELISA, serum and urinary LCN2 levels were measured in 36 patients with hematologic malignancies who transiently became neutropenic by stem cell transplantation (SCT). To evaluate contribution of neutrophil-derived LCN2 in the physiologic blood LCN2 concentrations, we examined CCAAT/enhancer-binding protein ε (C/EBPε) knockout mice, which lack mature neutrophils.

RESULTS

In patients without AKI and bacterial infection, at 1 week after SCT, the median blood neutrophil counts became zero and serum LCN2 levels were decreased by 76 ± 6 % (p < 0.01), but urinary LCN2 levels were not altered. During neutropenic conditions, bacterial infection caused only a modest rise of serum LCN2 but AKI produced a marked rise of serum and urinary LCN2 levels. Serum LCN2 concentrations in C/EBPε knockout mice were reduced by 66 ± 11 % compared to wild-type mice (p < 0.05). Blood LCN2 existed predominantly in high molecular weight forms (>100 kDa), while urinary LCN2 was mainly in low molecular weight forms.

CONCLUSION

Our findings suggest that neutrophils are the major source of circulating LCN2 in normal and infected conditions, whereas blood and urinary LCN2 mainly derive from the kidney during AKI, and that the molecular forms and regulation of blood and urinary LCN2 are clearly distinct.

Tolerability and toxicological profile of pixantrone (Pixuvri®) in juvenile mice. Comparative study with doxorubicin

The tolerability of pixantrone dimaleate (Pixuvri(®)), an aza-anthracenedione for non-Hodgkin lymphoma, was assessed in juvenile mice after intraperitoneal injection. Twenty animals/sex/dose received pixantrone 15 or 27 mg/kg/day on Post-Natal-Days (PND) 10, 13, 17, 20, 35, 39 and 42 in comparison with doxorubicin, 3 mg/kg/day. Animals were sacrificed on PND 42, 73 and 96. All pixantrone animals survived, while doxorubicin induced 52.5% mortality and the surviving animals were sacrificed early due to severe toxicity. Recoverable bone marrow toxicity (pixantrone), and toxicity to thymus and reproductive organs (pixantrone, doxorubicin) were observed without nephro- or hepatotoxicity. Pixantrone was measurable in plasma up to 2h (occasionally 6h) post-dose. At PND 42, mean Cmax and AUC values increased proportionally with dose, without gender difference or accumulation. Pixantrone showed minimal cardiotoxicity in males and negligible in females at PND 96. Doxorubicin induced significant heart weight reduction at PND 42, however early sacrifice impeded further cardiac assessments.

Effect of glomerular filtration rate impairment on diagnostic performance of neutrophil gelatinase-associated lipocalin and B-type natriuretic peptide as markers of acute cardiac and renal failure in chronic kidney disease patients

INTRODUCTION

Cardio-renal syndromes are characterized by the impairment of cardiac and renal functions. Plasma and urinary neutrophil gelatinase-associated lipocalin (NGAL), and plasma B-type natriuretic peptide (BNP) are markers of acute kidney injury (AKI) and heart failure (HF), respectively.

METHODS

GFR (99mTc-DTPA), plasma BNP, and plasma and urinary concentrations of NGAL were measured in 310 clinically stable CKD patients, at functional stages from 1 to 5. Serum and urinary low-molecular-weight proteins cystatin C and β2-microglobulin, and urinary tubular enzymes were measured for comparison. Plasma BNP, NGAL, cystatin C and β2-microglobulin were measured also in 31 maintenance hemodialysis patients.

RESULTS

Plasma NGAL increased with the reduction of GFR in CKD patients from stage 2. In the different CKD stages modest differences were found for BNP values. Urinary NGAL increased slightly but significantly in patients at CKD stages 4 and 5, similarly to urinary cystatin C and β2-microglobulin. In maintenance hemodialysis patients, plasma NGAL and BNP were markedly increased, and high-flux hemodialysis significantly decreased their plasma concentrations.

CONCLUSIONS

Plasma NGAL increases markedly with the reduction in GFR, generating a very high number of false positive diagnoses of AKI in stable CKD patients. The grade of GFR impairment and the cause of kidney disease have a lower effect on urinary NGAL and on plasma BNP. In any case, specific reference values of NGAL and BNP should be used in chronic kidney disease patients, according to their functional stage, when assessing acute kidney injury, heart failure, and cardio-renal syndromes in patients with impaired GFR.

Tolvaptan delays the onset of end-stage renal disease in a polycystic kidney disease model by suppressing increases in kidney volume and renal injury

Tolvaptan, a selective vasopressin V2 receptor antagonist, slows the increase in total kidney volume and the decline in kidney function in patients with the results of the Tolvaptan Efficacy and Safety in Management of Autosomal Dominant Polycystic Kidney Disease and Outcome (TEMPO) 3:4 trial. However, it was unclear which dose of tolvaptan was optimal or whether tolvaptan was able to delay progression to end-stage renal disease (ESRD). Here we examined the relationship with aquaresis and the inhibitory effect on cyst development in short-term treatment and mortality as an index of ESRD in long-term treatment with tolvaptan using DBA/2FG-pcy mice, an animal model of nephronophthisis. With short-term treatment from 5 to 15 weeks of age, tolvaptan (0.01-0.3% via diet) dose-dependently enhanced aquaresis, prevented increases in kidney weight and cyst volume, and was associated with significant reductions in kidney cAMP levels and extracellular signal-regulated kinase activity. Maximal effects of tolvaptan on aquaresis and the prevention of development of polycystic kidney disease (PKD) were obtained at 0.1%. Interestingly, tolvaptan also dose-dependently reduced urinary neutrophil gelatinase-associated lipocalin levels in correlation with the kidney volume. With long-term treatment from 5 to 29 weeks of age, tolvaptan significantly attenuated the increase in kidney volume by up to 50% and reduced urinary albumin excretion. Furthermore, tolvaptan significantly reduced the mortality rate to 20%, compared with 60% in the control group. These data indicate that tolvaptan may delay the onset of ESRD in PKD by suppressing the increases in kidney volume and renal injury, providing a promising treatment for PKD.

Neutrophil gelatinase-associated lipocalin in dogs with naturally occurring renal diseases

Background

Neutrophil gelatinase–associated lipocalin (NGAL) is released from renal tubular cells after injury and serves in humans as a real‐time indicator of active kidney damage, including acute kidney injury (AKI) and chronic kidney disease (CKD). However, NGAL concentrations in dogs with naturally occurring AKI or CKD rarely have been explored in detail.

Hypothesis/Objectives

The goal of this study was to evaluate whether NGAL can serve as a useful biomarker in dogs with naturally occurring renal disease.

Animals

Client‐owned dogs with renal disease (57) and control dogs without any disease (12) were examined.

Methods

Serum NGAL (sNGAL) and urine NGAL (uNGAL) concentrations were measured in each animal by a newly developed ELISA system. Demographic, hematologic, and serum biochemical data were recorded. Survival attributable to AKI and CKD was evaluated at 30 days and 90 days, respectively.

Results

Serum and urine NGAL concentrations in azotemic dogs were significantly higher than in nonazotemic dogs and were highly correlated with serum creatinine concentration (P < .05). Among CKD dogs, death was associated with significantly higher sNGAL and uNGAL concentrations compared with survivors. Receiver‐operating characteristic curve (ROC) analysis showed that sNGAL was better than serum creatinine concentration when predicting clinical outcomes for CKD dogs (P < .05). The best cutoff point for sNGAL was 50.6 ng/mL, which gave a sensitivity and a specificity of 76.9 and 100%, respectively. Furthermore, dogs that had higher concentrations of sNGAL survived for a significantly shorter time.

Conclusion

sNGAL is a useful prognostic marker when evaluating dogs with CKD.

Plasma and urine neutrophil gelatinase-associated lipocalin (NGAL) in dogs with acute kidney injury or chronic kidney disease

Background

Neutrophil gelatinase–associated lipocalin (NGAL) is a protein that is used in human medicine as a real‐time indicator of acute kidney injury (AKI).

Hypothesis

Dogs with AKI have significantly higher plasma NGAL concentration and urine NGAL‐to‐creatinine ratio (UNCR) compared with healthy dogs and dogs with chronic kidney disease (CKD).

Animals

18 healthy control dogs, 17 dogs with CKD, and 48 dogs with AKI.

Methods

Over a period of 1 year, all dogs with renal azotemia were prospectively included. Urine and plasma samples were collected during the first 24 hours after presentation or after development of renal azotemia. Plasma and urine NGAL concentrations were measured with a commercially available canine NGAL Elisa Kit (Bioporto® Diagnostic) and UNCR was calculated. A single‐injection plasma inulin clearance was performed in the healthy dogs.

Results

Median (range) NGAL plasma concentration in healthy dogs, dogs with CKD, and AKI were 10.7 ng/mL (2.5–21.2), 22.0 ng/mL (7.7–62.3), and 48.3 ng/mL (5.7–469.0), respectively. UNCR was 2 × 10⁻⁸ (0–46), 1,424 × 10⁻⁸ (385–18,347), and 2,366 × 10⁻⁸ (36–994,669), respectively. Dogs with renal azotemia had significantly higher NGAL concentrations and UNCR than did healthy dogs (P < .0001 for both). Plasma NGAL concentration was significantly higher in dogs with AKI compared with dogs with CKD (P = .027).

Conclusions and Clinical Importance

Plasma NGAL could be helpful to differentiate AKI from CKD in dogs with renal azotemia.

Neutrophil gelatinase associated lipocalin in acute kidney injury

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) is a member of the lipocalin family of proteins. Usually, NGAL is produced and secreted by kidney tubule cells at low levels, but the amount produced and secreted into the urine and serum increases dramatically after ischemic, septic, or nephrotoxic injury of the kidneys. The purpose of our review article is to summarize the role of NGAL in acute kidney injury (AKI), emergent, and intensive care.

METHODS

A PubMed search was performed (only English-language articles concerning human subjects were considered) using each of the following search term combinations: neutrophil gelatinase-associated lipocalin OR NGAL and acute kidney injury OR AKI; cardiac surgery; heart failure OR cardiology; intensive care; emergency department OR emergency medicine; nephropathy OR nephrotoxicity and transplantation.

RESULTS

The results of our search yielded 339 articles. Of the 339 articles, 160 were eligible for review based on the predefined criteria for inclusion.

CONCLUSION

Based on the evidence reviewed, it is clear that patient NGAL level is an appropriate, sensitive, and specific early biomarker of AKI caused by a variety of different etiologies. It is advised that a multidisciplinary group of experts come together to make recommendations and propose a consensus of clinical procedures to advance the most efficacious NGAL monitoring protocol for early detection and treatment of patients with AKI.

The small fibrinopeptide Bβ15-42 as renoprotective agent preserving the endothelial and vascular integrity in early ischemia reperfusion injury in the mouse kidney

Disruption of the renal endothelial integrity is pivotal for the development of a vascular leak, tissue edema and consequently acute kidney injury. Kidney ischemia amplifies endothelial activation and up-regulation of pro-inflammatory mechanisms. After restoring a sufficient blood flow, the kidney is damaged through complex pathomechanisms that are classically referred to as ischemia and reperfusion injury, where the disruption of the inter-endothelial connections seems to be a crucial step in this pathomechanism. Focusing on the molecular cell-cell interaction, the fibrinopeptide Bβ_15–42 prevents vascular leakage by stabilizing these inter-endothelial junctions. The peptide associates with vascular endothelial-cadherin, thus preventing early kidney dysfunction by preserving blood perfusion efficacy, edema formation and thus organ dysfunction. We intended to demonstrate the early therapeutic benefit of intravenously administered Bβ_15–42 in a mouse model of renal ischemia and reperfusion. After 30 minutes of ischemia, the fibrinopeptide Bβ_15–42 was administered intravenously before reperfusion was commenced for 1 and 3 hours. We show that Bβ_15–42 alleviates early functional and morphological kidney damage as soon as 1 h and 3 h after ischemia and reperfusion. Mice treated with Bβ_15–42 displayed a significantly reduced loss of VE-cadherin, indicating a conserved endothelial barrier leading to less neutrophil infiltration which in turn resulted in significantly reduced structural renal damage. The significant reduction in tissue and serum neutrophil gelatinase-associated lipocalin levels reinforced our findings. Moreover, renal perfusion analysis by color duplex sonography revealed that Bβ_15–42 treatment preserved resistive indices and even improved blood velocity. Our data demonstrate the efficacy of early therapeutic intervention using the fibrinopeptide Bβ_15–42 in the treatment of acute kidney injury resulting from ischemia and reperfusion. In this context Bβ_15–42 may act as a potent renoprotective agent by preserving the endothelial and vascular integrity.

Urinary neutrophil gelatinase-associated lipocalin predicts graft loss after acute kidney injury in kidney transplant

OBJECTIVE

Establish the prognostic value for graft loss of urinary neutrophil gelatinase-associated lipocalin (uNGAL), kidney injury molecule-1 (uKIM-1), interleukin-18 (uIL-18), and heat shock protein 72 (uHsp72) in kidney transplant recipients (KTR) with acute kidney injury (AKI).

METHODS

Biomarkers were measured in 67 KTR with AKI caused by different entities.

RESULTS

After 1 year, 11 KTR with graft loss had higher uNGAL compared to KTR without loss (p < 0.001). There were no differences for uKIM-1, uIL-18 and uHsp-72. uNGAL >200 ng/mL had 84% sensitivity and 86% specificity for graft loss (ROC AUC: 0.89, 95% CI: 0.81-0.97). uNGAL may be useful to predict graft loss after AKI.

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.

Protective effect of ginsenoside Rb1 against intestinal ischemia-reperfusion induced acute renal injury in mice

Ginsenoside Rb1 (RB1), the most clinically effective constituent of ginseng, possesses a variety of biological activities. The objectives of this study were to investigate the protective effects of RB1 and its underlying mechanism on renal injury induced by intestinal ischemia-reperfusion (IIR) in mice. RB1 was administered prior to inducing IIR achieved by occluding the superior mesenteric artery for 45 min followed by 120 min of reperfusion. All-trans-retinoic acid (ATRA) was used as an inhibitor of NF-E2-related factor-2 (Nrf2) signaling. Adult male C57BL/6J mice were randomly divided into six groups: (1) sham group, (2) IIR group, (3) RB1 group, (4) sham + ATRA group, (5) IIR + ATRA group, and (6) RB1 + ATRA group. Intestinal histology and pathological injury score were observed. Intestinal mucosal injury was also evaluated by measuring serum diamine oxidase (DAO). Renal injury induced by IIR was characterized by increased levels of histological severity score, blood urea nitrogen (BUN), serum creatinine (Scr) and neutrophil gelatinase-associated lipocalin (NGAL), which was accompanied with elevated renal TUNEL-positive cells and the Bcl-2/Bax expression ratio. RB1 significantly reduced renal injury and apoptosis as compared with IIR group, which was reversed by ATRA treatment. Immunohistochemistry and Western blot analysis demonstrated that RB1 significantly upregulated the protein expression of heme oxygenase-1 (HO-1) and Nrf2, which were attenuated by ATRA treatment. Taken together, these results suggest that the protective effects of RB1 pretreatment against renal injury induced by IIR are associated with activation of the Nrf2/ anti-oxidant response element (ARE) pathway.

Early prediction of polymyxin-induced nephrotoxicity with next-generation urinary kidney injury biomarkers

Despite six decades of clinical experience with the polymyxin class of antibiotics, their dose-limiting nephrotoxicity remains difficult to predict due to a paucity of sensitive biomarkers. Here, we evaluate the performance of standard of care and next-generation biomarkers of renal injury in the detection and monitoring of polymyxin-induced acute kidney injury in male Han Wistar rats using colistin (polymyxin E) and a polymyxin B (PMB) derivative with reduced nephrotoxicity, PMB nonapeptide (PMBN). This study provides the first histopathological and biomarker analysis of PMBN, an important test of the hypothesis that fatty acid modifications and charge reductions in polymyxins can reduce their nephrotoxicity. The results indicate that alterations in a panel of urinary kidney injury biomarkers can be used to monitor histopathological injury, with Kim-1 and α-GST emerging as the most sensitive biomarkers outperforming clinical standards of care, serum or plasma creatinine and blood urea nitrogen. To enable the prediction of polymyxin-induced nephrotoxicity, an in vitro cytotoxicity assay was employed using human proximal tubule epithelial cells (HK-2). Cytotoxicity data in these HK-2 cells correlated with the renal toxicity detected via safety biomarker data and histopathological evaluation, suggesting that in vitro and in vivo methods can be incorporated within a screening cascade to prioritize polymyxin class analogs with more favorable renal toxicity profiles.

Obesity-mediated autophagy insufficiency exacerbates proteinuria-induced tubulointerstitial lesions

Obesity is an independent risk factor for renal dysfunction in patients with CKDs, including diabetic nephropathy, but the mechanism underlying this connection remains unclear. Autophagy is an intracellular degradation system that maintains intracellular homeostasis by removing damaged proteins and organelles, and autophagy insufficiency is associated with the pathogenesis of obesity-related diseases. We therefore examined the role of autophagy in obesity-mediated exacerbation of proteinuria-induced proximal tubular epithelial cell damage in mice and in human renal biopsy specimens. In nonobese mice, overt proteinuria, induced by intraperitoneal free fatty acid-albumin overload, led to mild tubular damage and apoptosis, and activated autophagy in proximal tubules reabsorbing urinary albumin. In contrast, diet-induced obesity suppressed proteinuria-induced autophagy and exacerbated proteinuria-induced tubular cell damage. Proximal tubule-specific autophagy-deficient mice, resulting from an Atg5 gene deletion, subjected to intraperitoneal free fatty acid-albumin overload developed severe proteinuria-induced tubular damage, suggesting that proteinuria-induced autophagy is renoprotective. Mammalian target of rapamycin (mTOR), a potent suppressor of autophagy, was activated in proximal tubules of obese mice, and treatment with an mTOR inhibitor ameliorated obesity-mediated autophagy insufficiency. Furthermore, both mTOR hyperactivation and autophagy suppression were observed in tubular cells of specimens obtained from obese patients with proteinuria. Thus, in addition to enhancing the understanding of obesity-related cell vulnerability in the kidneys, these results suggest that restoring the renoprotective action of autophagy in proximal tubules may improve renal outcomes in obese patients.

Measurement of renal function in patients with chronic kidney disease

Chronic kidney disease affects millions of people worldwide and is associated with an increased morbidity and mortality as a result of kidney failure and cardiovascular disease. Accurate assessment of kidney function is important in the clinical setting as a screening tool and for monitoring disease progression and guiding prognosis. In clinical research, the development of new methods to measure kidney function accurately is important in the search for new therapeutic targets and the discovery of novel biomarkers to aid early identification of kidney injury. This review considers different methods for measuring kidney function and their contribution to the improvement of detection, monitoring and treatment of chronic kidney disease.

Urinary TNF-α and NGAL are correlated with the progression of nephropathy in patients with type 2 diabetes

The aim of this study was to investigate the correlation of the proinflammatory marker tumor necrosis factor-α (TNF-α) and the tubular marker neutrophil gelatinase-associated lipocalin (NGAL) with the progression of the early stage of type 2 diabetic nephropathy (DN). Baseline levels of urinary TNF-α and NGAL were measured in 63 non-diabetic controls and 201 patients with type 2 diabetes and different albuminuria statuses. The patients with diabetes (n=125) with normo- or microalbuminuria were subsequently followed-up for 28 (25-32) months, with routine measurements of creatinine and urinary albumin excretion (UAE). It was observed that baseline levels of urinary TNF-α and NGAL were significantly elevated and correlated with the severity of albuminuria in patients with diabetes. During the follow-up, the urinary levels of TNF-α and NGAL were observed to be significantly correlated with a rapid decline in the estimated glomerular filtration rate (eGFR). Following adjustment for other progression promoters, including albuminuria, TNF-α remained a significant predictor of eGFR decline. These results suggest that inflammation is important in the pathogenesis of DN and indicate that TNF-α may be used as an independent predictor for the progression of DN at the early stage.

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.

Evaluation of neutrophil gelatinase-associated lipocalin as a marker of kidney injury in dogs

BACKGROUND

Acute kidney injury (AKI) is a common and often fatal disorder in dogs.

HYPOTHESIS

Urine neutrophil gelatinase-associated lipocalin (NGAL)/creatinine ratio is a sensitive and specific biomarker of AKI in dogs.

ANIMALS

Ninety-four dogs.

METHODS

Prospective study. Dogs were classified as follows: (1) healthy dogs, (2) dogs with lower urinary tract disorders, (3) dogs with chronic kidney disease (CKD), (4) dogs with azotemic International Renal Interest Society (IRIS) AKI Grades II-V, and (5) dogs with IRIS AKI Grade I (nonazotemic). Urinary NGAL was quantitated in each dog using an ELISA assay and concentrations were expressed as a ratio to urinary creatinine concentration from the same specimen, and designated the urinary NGAL/creatinine ratio (UNCR).

RESULTS

There was a significant difference in UNCR among the study groups (P < .001). Both the azotemic and nonazotemic AKI groups had higher UNCR when compared with all other groups (P < .001 for all pairs). There was a statistically significant difference in UNCR between dogs diagnosed with CKD compared with dogs with lower urinary tract diseases (P = .005) as well as between dogs with CKD and healthy dogs (P = .001). Receiver operator characteristics (ROC) analysis of UNCR as an indicator of azotemic and nonazotemic AKI had an area under the ROC curve of 0.94 and 0.96, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

NGAL/creatinine ratio is a sensitive and specific marker of AKI. It can be used to screen patients at risk for AKI and can be utilized to diagnose milder forms of AKI potentially earlier in the course of the disease.

Neutrophil gelatinase-associated lipocalin, a sensitive urinary biomarker of acute kidney injury in dogs receiving gentamicin

A sensitive urinary biomarker for acute kidney injury (AKI) was investigated in beagle dogs with nephrotoxicity induced by gentamicin. Gentamicin sulphate at 25 or 50 mg/kg was injected (s.c.) for 9 days, and conventional urinalysis, ELISA assay of neutrophil gelatinase-associated lipocal (NGAL) in urine, blood chemistry, and pathological examinations were performed. The dog given gentamicin at 25 mg/kg only showed slight deposition of lysosomal granules in the proximal tubular epithelium of the kidneys without any other significant changes even though urinary NGAL was elevated on Day 10 (day of necropsy). In the dog receiving gentamicin at 50 mg/kg, increases in urinary NGAL were observed on Days 3 and 5, and absence of urination, marked increases in serum urea nitrogen and creatinine, enlargement and discoloration of the kidneys with marked necrosis, and swelling of proximal epithelium were observed. In conclusion, urinary NGAL is considered to be a candidate as a sensitive predictable biomarker of AKI in the gentamicin-induced nephrotoxicity model in dogs.

Lipocalin-2 serum levels are increased in acute hepatic failure

Lipocalin-2 (LCN-2), which is expressed in immunocytes as well as hepatocytes, is upregulated in cells under stress from infection or inflammation with increase in serum levels. We sought to investigate the relevance of LCN-2 in the setting of acute hepatic failure, particularly when addressed with the molecular adsorbent recirculating system (MARS). We measured serum LCN-2 concentrations with enzyme-linked immunosorbent assay (ELISA) in 8 patients with acute-on-chronic-liver failure (ACLF) and acute liver failure (ALF) who were treated with MARS. The controls were 14 patients with stable chronic hepatic failure (CHF). LCN-2 was determined immediately before and after the first MARS session. Baseline LCN-2 serum concentrations were significantly increased among ACLF and ALF patients as compared with CHF (P = .004 and P = .0086, respectively). There was no significant difference between the ALF and ACLF group. Moreover, serum LCN-2 levels did not change significantly during the MARS treatment. Serum LCN-2 levels, therefore, may be useful to discern acute from chronic hepatic failure and to monitor the course as well as the severity of the disease.

NGAL and NT-proBNP levels in diabetic patients with macroproteinuria

BACKGROUND

In patients with heart failure plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) levels are correlated to urine neutrophil gelatinase-associated lipocalin (NGAL) levels. We prospectively evaluated the relationship among glomerular filtration rate (eGFR), urine albumin-to-creatinine ratio (ACR), urine and serum NGAL and NT-proBNP levels in 20 type II diabetic patients with macroalbuminuria at 4-month intervals.

RESULTS

Compared with 20 age, gender-matched healthy controls, diabetic patients had higher urine and serum NGAL, serum NT-proBNP and lower eGFR. The eGFR of the patients at the baseline, the 4th and the 8th month were 29.6 ± 12.0, 27.8 ± 13.7 and 22.9 ± 10.4 mL/min/1.73 m(2), respectively. No significant change in urine NGAL levels was detected (p > 0.05), whereas there were significant increases in NT-proBNP, serum NGAL and urine ACR and significant decrease in eGFR as the study progressed (p < 0.05). Both the baseline and the 4th month urine ACR were positively correlated to NT-proBNP levels measured at the same periods (r: 0.451; p: 0.046; r: 0.489; p: 0.029 respectively). In all measurements, urine ACR was negatively correlated to serum albumin levels measured at the same periods (r: -0.792; p: 0.000; r: -0.716; p: 0.000; r: -0.531; p: 0.016 respectively). None of eGFR measurements was correlated with NT-proBNP (p > 0.05). Neither serum NGAL nor urinary NGAL levels are associated with NT-proBNP (p > 0.05).

CONCLUSION

Our findings show an association between NT-proBNP and proteinuria in type II diabetic patients with macroalbuminuria but not with serum and urine NGAL.

Neutrophil gelatinase-associated lipocalin and end-stage renal disease: it is not all about the kidneys!

INTRODUCTION

Neutrophil gelatinase-associated lipocalin (NGAL) is a powerful biomarker for the early detection of acute kidney injury. However, recent data suggest that NGAL also plays an important role in chronic kidney disease (CKD), reflecting the level of acute kidney damage within the CKD condition. To study whether elevated NGAL levels in CKD are a consequence of damaged tubular cells or rather due to extrarenal production, we investigated NGAL levels in anephric patients on dialysis.

METHODS

Plasma NGAL levels were investigated in 14 dialysis patients who underwent bilateral nephrectomy (anephric group), 18 anuric dialysis patients with remaining kidneys (dialysis group) and 12 healthy patients (healthy group).

RESULTS

Plasma NGAL levels were significantly lower in the healthy group compared with the anephric group (143 vs. 981 ng/mL; P < 0·001) or the dialysis group (143 vs. 838 ng/mL; P < 0·001), respectively. However, NGAL levels did not differ between the anephric group and the dialysis group (981 vs. 838 ng/mL; P = 0·19).

DISCUSSION

Assuming that NGAL is highly expressed in chronically damaged kidneys due to tubular stress, there should be significantly less NGAL in anephric patients compared with anuric dialysis patients with remaining kidneys. In contrast to this hypothesis, we found no difference in NGAL expression between these two groups, proving the entire extrarenal NGAL production in anephric patients and suggesting that the tubular NGAL expression seems to be negligible in anuric dialysis patients.

Methylmercury exposure increases lipocalin related (lpr) and decreases activated in blocked unfolded protein response (abu) genes and specific miRNAs in Caenorhabditis elegans

Methylmercury (MeHg) is a persistent environmental and dietary contaminant that causes serious adverse developmental and physiologic effects at multiple cellular levels. In order to understand more fully the consequences of MeHg exposure at the molecular level, we profiled gene and miRNA transcripts from the model organism Caenorhabditis elegans. Animals were exposed to MeHg (10 μM) from embryo to larval 4 (L4) stage and RNAs were isolated. RNA-seq analysis on the Illumina platform revealed 541 genes up- and 261 genes down-regulated at a cutoff of 2-fold change and false discovery rate-corrected significance q < 0.05. Among the up-regulated genes were those previously shown to increase under oxidative stress conditions including hsp-16.11 (2.5-fold), gst-35 (10.1-fold), and fmo-2 (58.5-fold). In addition, we observed up-regulation of 6 out of 7 lipocalin related (lpr) family genes and down regulation of 7 out of 15 activated in blocked unfolded protein response (abu) genes. Gene Ontology enrichment analysis highlighted the effect of genes related to development and organism growth. miRNA-seq analysis revealed 6-8 fold down regulation of mir-37-3p, mir-41-5p, mir-70-3p, and mir-75-3p. Our results demonstrate the effects of MeHg on specific transcripts encoding proteins in oxidative stress responses and in ER stress pathways. Pending confirmation of these transcript changes at protein levels, their association and dissociation characteristics with interaction partners, and integration of these signals, these findings indicate broad and dynamic mechanisms by which MeHg exerts its harmful effects.

Role of lipocalin-2-chemokine axis in the development of neuropathic pain following peripheral nerve injury

Lipocalin 2 (LCN2), which is also known as 24p3 and neutrophil gelatinase-associated lipocalin (NGAL), binds small, hydrophobic ligands and interacts with cell surface receptor 24p3R to regulate diverse cellular processes. In the present study, we examined the role of LCN2 in the pathogenesis of neuropathic pain using a mouse model of spared nerve injury (SNI). Lcn2 mRNA levels were significantly increased in the dorsal horn of the spinal cord after SNI, and LCN2 protein was mainly localized in neurons of the dorsal and ventral horns. LCN2 receptor 24p3R was expressed in spinal neurons and microglia after SNI. Lcn2-deficient mice exhibited significantly less mechanical pain hypersensitivity during the early phase after SNI, and an intrathecal injection of recombinant LCN2 protein elicited mechanical pain hypersensitivity in naive animals. Lcn2 deficiency, however, did not affect acute nociceptive pain. Lcn2-deficient mice showed significantly less microglial activation and proalgesic chemokine (CCL2 and CXCL1) production in the spinal cord after SNI than wild-type mice, and recombinant LCN2 protein induced the expression of these chemokines in cultured neurons. Furthermore, the expression of LCN2 and its receptor was detected in neutrophils and macrophages in the sciatic nerve following SNI, suggesting the potential role of peripheral LCN2 in neuropathic pain. Taken together, our results indicate that LCN2 plays a critical role in the development of pain hypersensitivity following peripheral nerve injury and suggest that LCN2 mediates neuropathic pain by inducing chemokine expression and subsequent microglial activation.

[Analysis of neutrophil gelatinase-associated lipocalin in the critical patient]

OBJECTIVE

To determine if NGAL value exceeding 150 ng/mL is a good diagnostic test for acute renal failure in critically ill patients.

DESIGN

Prospective, observational cohort.

SETTING

Intensive Care Unit and Cardiac Surgery Intensive Care Service at Hospital Germans Trias I Pujol.

PARTICIPANTS

Patients admitted to the Intensive Care department the Designated days in the studio.

INTERVENTIONS

Analysis of serum creatinine blood given from 7 days prior to the start of the study, and daily during 4 weeks and by determination of NGAL urine test in frozen sample, analyzer ARCHITECT (Abbott Diagnostics) determined by immunoassay the day baseline and 2 times a week for 4 weeks, analysis of the stay and mortality.

RESULTS

A total of 529 NGAL samples were obtained from 46 patients. 37% of patients had a value of NGAL>150 ng/mL. The Sensivity of the test to diagnose acute renal failure was 69%, Specifity was 75,7%. However, the Positive Predictive Test Value was 53%, which means that 47% of patients with high NGAL did not develop AKI. A NGAL >150 mg/dL was associated with a significantly higher SOFA and a longer stay in the ICU. The mortality of patients with elevated NGAL was 58.8%.

CONCLUSIONS

A NGAL>150 ng/mL does not seem to be an excellent test for AKI in critically ill patients but is associated with a worse prognosis.

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.

Distinct injury markers for the early detection and prognosis of incident acute kidney injury in critically ill adults with preserved kidney function

The use of novel biomarkers to detect incident acute kidney injury (AKI) in the critically ill is hindered by heterogeneity of injury and the potentially confounding effects of prevalent AKI. Here we examined the ability of urine NGAL (NGAL), L-type Fatty Acid Binding Protein (L-FABP), and Cystatin C to predict AKI development, death, and dialysis in a nested case-control study of 380 critically ill adults with an eGFR over 60 ml/min/1.73 m². One-hundred thirty AKI cases were identified following biomarker measurement and were compared to 250 controls without AKI. Areas under the receiver-operator characteristic curves (AUC-ROCs) for discriminating incident AKI from non-AKI were 0.58(95%CI: 0.52-0.64), 0.59(0.52-0.65), and 0.50(0.48-0.57) for urine NGAL, L-FABP, and Cystatin C, respectively. The combined AUC-ROC for NGAL and L-FABP was 0.59(56-0.69). Both urine NGAL and L-FABP independently predicted AKI during multivariate regression; however, risk reclassification indices were mixed. Neither urine biomarker was independently associated with death or acute dialysis [NGAL hazard ratio 1.35(95%CI: 0.93-1.96), L-FABP 1.15(0.82-1.61)] though both independently predicted the need for acute dialysis [NGAL 3.44(1.73-6.83), L-FABP 2.36(1.30-4.25)]. Thus, urine NGAL and L-FABP independently associated with the development of incident AKI and receipt of dialysis but exhibited poor discrimination for incident AKI using conventional definitions.

Current challenges and controversies in drug-induced liver injury

Current key challenges and controversies encountered in the identification of potentially hepatotoxic drugs and the assessment of drug-induced liver injury (DILI) are covered in this article. There is substantial debate over the classification of DILI itself, including the definition and validity of terms such as 'intrinsic' and 'idiosyncratic'. So-called idiosyncratic DILI is typically rare and requires one or more susceptibility factors in individuals. Consequently, it has been difficult to reproduce in animal models, which has limited the understanding of its underlying mechanisms despite numerous hypotheses. Advances in predictive models would also help to enable preclinical elimination of drug candidates and development of novel biomarkers. A small number of liver laboratory tests have been routinely used to help identify DILI, but their interpretation can be limited and confounded by multiple factors. Improved preclinical and clinical biomarkers are therefore needed to accurately detect early signals of liver injury, distinguish drug hepatotoxicity from other forms of liver injury, and differentiate mild from clinically important liver injury. A range of potentially useful biomarkers are emerging, although so far most have only been used preclinically, with only a few validated and used in the clinic for specific circumstances. Advances in the development of genomic biomarkers will improve the prediction and detection of hepatic injury in future. Establishing a definitive clinical diagnosis of DILI can be difficult, since it is based on circumstantial evidence by excluding other aetiologies and, when possible, identifying a drug-specific signature. DILI signals based on standard liver test abnormalities may be affected by underlying diseases such as hepatitis B and C, HIV and cancer, as well as the concomitant use of hepatotoxic drugs to treat some of these conditions. Therefore, a modified approach to DILI assessment is justified in these special populations and a suggested framework is presented that takes into account underlying disease when evaluating DILI signals in individuals. Detection of idiosyncratic DILI should, in some respects, be easier in the postmarketing setting compared with the clinical development programme, since there is a much larger and more varied patient population exposure over longer timeframes. However, postmarketing safety surveillance is currently limited by the quantity and quality of information available to make an accurate diagnosis, the lack of a control group and the rarity of cases. The pooling of multiple healthcare databases, which could potentially contain different types of patient data, is advised to address some of these deficiencies.

urinary biomarkers in relapsing antineutrophil cytoplasmic antibody-associated vasculitis

OBJECTIVE

Glomerulonephritis (GN) is common in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), but tools for early detection of renal involvement are imperfect. We investigated 4 urinary proteins as markers of active renal AAV: alpha-1 acid glycoprotein (AGP), kidney injury molecule-1 (KIM-1), monocyte chemoattractant protein-1 (MCP-1), and neutrophil gelatinase-associated lipocalin (NGAL).

METHODS

Patients with active renal AAV (n = 20), active nonrenal AAV (n = 16), and AAV in longterm remission (n = 14) were identified within a longitudinal cohort. Urinary biomarker concentrations (by ELISA) were normalized for urine creatinine. Marker levels during active AAV were compared to baseline remission levels (from 1-4 visits) for each patient. Areas under receiver-operating characteristic curves (AUC), sensitivities, specificities, and likelihood ratios (LR) comparing disease states were calculated.

RESULTS

Baseline biomarker levels varied among patients. All 4 markers increased during renal flares (p < 0.05). MCP-1 discriminated best between active renal disease and remission: a 1.3-fold increase in MCP-1 had 94% sensitivity and 89% specificity for active renal disease (AUC = 0.93, positive LR 8.5, negative LR 0.07). Increased MCP-1 also characterized 50% of apparently nonrenal flares. Change in AGP, KIM-1, or NGAL showed more modest ability to distinguish active renal disease from remission (AUC 0.71-0.75). Hematuria was noted in 83% of active renal episodes, but also 43% of nonrenal flares and 25% of remission samples.

CONCLUSION

Either urinary MCP-1 is not specific for GN in AAV, or it identifies early GN not detected by standard assessment and thus has potential to improve care. A followup study with kidney biopsy as the gold standard is needed.

Urinary Neutrophil Gelatinase Associated Lipocalin (NGAL) for Early Diagnosis of Acute Kidney Injury in Renal Transplant Recipients

Background

Early predictive biomarkers for acute kidney injury (AKI) such as neutrophil elatinase-associated lipocalin (NGAL) could identify patients who may benefit from early initiation of treatment.

Objectives

We aimed to obtain a cut off point for AKI prediction by urine NGAL in kidney transplantation.

Patients and Methods

In a prospective cohort study, 64 adult who underwent kidney transplantation from living or deceased donors at Baqiyatallah transplant center between April 2009 and January 2010 were included. Patients divided into two groups based on the presence or absence of graft dysfunction. In this study, early graft dysfunction (post transplantation AKI) was defined as Cr level more than 1.5 mg/dL on the second postoperative day.

Results

Post-transplant AKI was observed in 31 recipients. Mean urinary NGAL level was greater in recipients with AKI (P = 0.024). In linear regression model, AKI was only factor affected on urinary NGAL level (B = 299.8, P = 0.009). The best sensitivity and specificity for AKI detection by urinary NGAL observed at 2 hour after operation with cut-off point 204 ng/mL.

Conclusions

Our study showed in those who developed early post transplantation graft dysfunction the best AUC-ROC for urine NGAL observed at a cut-off value of 204 ng/mL after 2 hour post transplantation.

Intrarenal resistance index for the assessment of acute renal injury in a rat liver transplantation model

Background

Acute kidney injury (AKI) is a common complication after liver transplantation (LT) and associated with a high mortality. The renal resistive index (RI) is used to assess early renal function impairment in critical care patients. However, limited data are available concerning changes of renal RI and the development of AKI early after reperfusion. We approached to investigate the changes of renal RI and AKI after reperfusion in a rat liver transplantation model.

Methods

Rats were randomly divided into sham group or LT group. Ten rats in each group were used for the hemodynamic study and twenty for Doppler measurements during the procedure. Ten rats were sacrificed 30 min or 2 h after the reperfusion. We harvested kidneys, serum and urine for further analysis of the renal function.

Results

The intrarenal RI increased significantly in the anhepatic stage and decreased significantly after the reperfusion in the LT group compared with sham group (P < 0.05). AKI was seen after the reperfusion in the LT group. No correlation was noted between the RI and renal function parameters 30 min after reperfusion.

Conclusions

The intrarenal RI increased significantly during the anhepatic stage, and decreased significantly early after the reperfusion. Intrarenal RI was unable to assess renal function in a rat liver transplantation model.