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

Serum neutrophil gelatinase-associated lipocalin the estimation of hospital prognosis in patients with ST-elevated myocardial infarction

We aimed to assess the clinical significance of serum levels of neutrophil gelatinase-associated lipocalin (sNGAL) for predicting in-hospital outcomes in patients with ST-elevated myocardial infarction (STEMI). Patients admitted within 24 hours of developing STEMI clinical symptoms were evaluated for sNGAL on hospitalization days 1 and 12. Recurrent myocardial infarction, early post-infarction angina, acute cerebrovascular accident, and death were assessed as adverse outcomes during hospitalization. The actors associated with adverse outcome were evaluated using univariate and multivariate regression analysis. Among the 260 STEMI patients included, 32% had ≥1 adverse in-hospital outcome, and significantly higher sNGAL on day 12, (but not on day 1) compared to sNGAL in patients with favorable outcome (p = 0.033). Type-2 diabetes mellitus, age > 60 years, reduced glomerular filtration rate during hospitalization, and high sNGAL on day 12 were identified as risk factors for adverse in-hospital outcome, associated with a 14% increase for each 1-year increment in age after 60 years, and a dramatic increase (3.2 times) for high sNGAL on day 12, with sNGAL ≥ 1.046 ng/ml indicating complicated hospitalization course. sNGAL concentration on the 12th day was associated with the existing adverse outcomes, acting as a marker of MI severity.

Measuring non-polyaminated lipocalin-2 for cardiometabolic risk assessment

Aims

Lipocalin‐2 is a pro‐inflammatory molecule characterized by a highly diversified pattern of expression and structure–functional relationships. In vivo, this molecule exists as multiple variants due to post‐translational modifications and/or protein–protein interactions. Lipocalin‐2 is modified by polyamination, which enhances the clearance of this protein from the circulation and prevents its excessive accumulation in tissues. On the other hand, animal studies suggest that non‐polyaminated lipocalin‐2 (npLcn2) plays a causal role in the pathogenesis of obesity‐associated medical complications. The present study examined the presence of npLcn2 in samples from healthy volunteers or patients with cardiac abnormalities and evaluated npLcn2 as a biomarker for cardiometabolic risk assessment.

Methods and results

Immunoassays were developed to quantify npLcn2 in blood and urine samples collected from 100 volunteers (59 men and 41 women), or venous plasma and pericardial fluid samples obtained from 37 cardiothoracic surgery patients. In healthy volunteers, npLcn2 levels in serum are significantly higher in obese and overweight than in lean subjects. After adjustment for age, gender, smoking, and body mass index (BMI), serum npLcn2 levels are positively correlated with heart rate, circulating triglycerides, high‐sensitivity C‐reactive protein (hsCRP), and creatinine in plasma. The npLcn2 levels in urine are significantly increased in subjects with metabolic syndrome and positively correlated with BMI, heart rate, circulating triglycerides, and urinary aldosterone. In cardiothoracic surgery patients, the circulating concentrations of npLcn2 are higher (more than two‐fold) than those of healthy volunteers and positively correlated with the accumulation of this protein in the pericardial fluid. Heart failure patients exhibit excessive expression and distribution of npLcn2 in mesothelial cells and adipocytes of the parietal pericardium, which are significantly correlated with the elevated plasma levels of npLcn2, total cholesterol, and creatinine.

Conclusions

Quantitative and qualitative evaluation of npLcn2 in human biofluid samples and tissue samples can be applied for risk assessment of healthy individuals and disease management of patients with obesity‐related cardiometabolic and renal complications.

Postoperative acute kidney injury

Acute kidney injury (AKI) after cardiac surgery is a common and serious complication. Several definitions of AKI have been proposed recently, and include both increases in serum creatinine levels and decreases in urine output as diagnostic criteria. The pathophysiology of postoperative AKI is complex and involves both ischemic injury and systemic inflammation. Identifying risk factors, such as old age, underlying diabetes, heart failure, and obesity, may aid in the application of preventative methods for postoperative AKI. Additionally, recognizing different risks after different types of surgical procedures would be valuable. Novel biomarkers that could detect AKI more precisely at an earlier time point are being investigated. Several new biomarkers have been assessed in large multi-center studies and are believed to accommodate conventional clinical findings in diagnosing postoperative AKI. In high-risk patients, preventative measures, such as the maintenance of adequate hemodynamics and sufficient fluid resuscitation, could lower the incidence of postoperative AKI. Avoiding nephrotoxic agents and optimizing preoperative hemoglobin levels to avoid excessive transfusions would also be beneficial. In situations in which medical management fails to maintain sufficient urine output and acid-base and electrolyte homeostasis, early initiation of renal replacement therapy should be considered.

The impact of calcineurin inhibitors on neutrophil gelatinase-associated lipocalin and fibroblast growth factor 23 in long-term kidney transplant patients

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL), a protein with bacteriostatic functions rapidly excreted from stimulated or damaged epithelial cells, is elevated in acute and chronic kidney disease. A calcineurin dependent signaling pathway for fibroblast growth factor 23 (FGF23) has been revealed, but the effect of calcineurin inhibitors (CNIs) on the levels of NGAL and markers of mineral metabolism in long-term kidney transplant patients has not been explored.

METHODS

In a cross-sectional study, 39 patients who received a first kidney transplant more than 10 years ago were split into two groups based on whether (n=28) or not (n=11) they used CNIs. Only patients with well-functioning grafts defined as an estimated glomerular filtration rate ≥45 mL/min per 1.73 m² were included.

RESULTS

The median levels of NGAL, intact parathyroid hormone (iPTH), and iFGF23 were significantly higher in CNI users vs CNI nonusers, 167.0 (134.0-235.0) ng/mL vs 105.0 (91.3-117.0) ng/mL, P<.001, 13.8 (10.0-17.3) pmol/L vs 8.4 (6.4-9.9) pmol/L, P=.003, and 81.6 (56.4-116.5) pg/mL vs 61.8 (43.3-72.1) pg/mL, P=.04 respectively.

CONCLUSIONS

The median levels of iFGF23 were higher in CNI users compared to CNI nonusers giving support to the notion of a CNI induced FGF23 resistance in the parathyroid. The net result of CNIs side effects needs to be further explored.

Plasma neutrophil gelatinase-associated lipocalin (NGAL) is an indicator of interstitial damage and a predictor of kidney function worsening of chronic kidney disease in the early stage: a pilot study

BACKGROUND

The aim of this study was to examine whether plasma neutrophil gelatinase-associated lipocalin (NGAL) levels predict the outcome of kidney function and correlate with the severity of tubulointerstitial damages in patients with chronic kidney disease (CKD).

METHODS

In this prospective 18-month cohort study of 112 patients with CKD between 2010 and 2011, associations between plasma NGAL levels and estimated glomerular filtration ratio (eGFR), further worsening of kidney function and histological lesion on kidney biopsy were investigated.

RESULTS

Serum levels of creatinine and eGFR before the study were 1.48 ± 0.65 mg/dl and 42.6 ± 22.0 ml/min/1.73 m². Median plasma NGAL level was 148.5 (83.75-248.25) ng/ml and showed no correlation with eGFR or age. 87 out of 112 patients were able to follow up for 18 months. Patients with higher levels of NGAL (>107.8 ng/ml) showed significantly more decrease in eGFR in CKD stage 1 or 2 than those with lower levels of NGAL (≦107.8 ng/ml), while there was no difference in change in eGFR in CKD stage 3-5 between patients with higher and lower levels of NGAL. In the kidney biopsy of 27 patients out of enrolled patients, plasma NGAL levels correlated significantly with the degree of interstitial cell infiltration and fibrosis, but did not correlate with that of glomerular sclerosis. In ROC analysis, plasma NGAL levels predicted tubulointerstitial cell infiltrations more accurately [AUC = 0.8300 than eGFR (AUC = 0.716)].

CONCLUSION

Plasma NGAL is a useful marker of interstitial lesions in patients with CKD and a predictor of further kidney worsening in the early CKD stage.

The relationship between circulating neutrophil gelatinase-associated lipocalin and early alteration of metabolic parameters is associated with dietary saturated fat intake in non-diabetic Korean women

Circulating neutrophil gelatinase-associated lipocalin (NGAL) is associated with obesity-related metabolic disorders. This study investigated the relationship between serum NGAL and early alteration of metabolic parameters in non-diabetic Korean women, particularly with respect to saturated fat (SFA) intake. Anthropometric parameters, fasting glycemic status, and levels of lipids, oxidative stress/inflammatory markers, and NGAL were measured in 82 non-diabetic Korean women [Super-healthy group (n=57) with 0 metabolic syndrome risk factor (MetS RF) and MetS-risk group (n=25) with MetS RF≥1]. Age, weight, waist circumference, blood pressure, fasting glucose, HbA1C, triglyceride, LDL and total-cholesterol, and NGAL levels were higher, and HDL-cholesterol was lower in the MetS-risk group than in the Super-healthy group. Age-adjusted serum NGAL levels were higher in the MetS-risk group than in the Super-healthy group. NGAL increased proportionally with increase in MetS RFs (p=0.038) and correlated positively with BMI, triglycerides, LDL- and total-cholesterol, interleukin-6, white blood cell count, and neutrophil%, and negatively with HDL-cholesterol and superoxide dismutase activity. Serum NGAL levels positively correlated with SFA intake before and after adjustment (age and BMI). Serum NGAL levels were higher in high-SFA consumers [≥7g/day, ≥7% of total calorie intake (TCI)] than in low-SFA consumers (<7g/day, <7% of TCI). Serum NGAL levels were highest in the MetS-risk group consuming higher SFA and lowest in the Super-healthy group consuming lower SFA. However, serum NGAL did not significantly differ between the low-SFA consuming MetS-risk and Super-healthy groups. The relationship between circulating NGAL and early alteration of metabolic parameters is associated with dietary SFA intake in non-diabetic Korean women.

Early detection of acute cisplatin nephrotoxicity: interest of urinary monitoring of proximal tubular biomarkers

Background

Renal toxicity induced by cisplatin (CisPt) is a clinical issue in patients with or without chronic kidney disease (CKD). Proximal tubular injury can result in acute kidney injury (AKI), which may compromise the course of chemotherapy and the prognosis. The purpose of this study was to investigate the time course of urinary markers of acute tubulotoxicity and to assess the usefulness of such monitoring in a routine clinical setting.

Methods

This work is an open prospective pilot study carried out among 23 patients receiving a platinum-based chemotherapy. Individual comorbidities, plasma parameters of kidney function (urea, creatinine) and estimated glomerular filtration rate were registered. Urinary excretion of leucine aminopeptidase, neutrophil gelatinase-associated lipocalin, cystatin C, liver fatty acid-binding protein and interleukin-18 were monitored during successive chemotherapy cycles. Episodes of AKI were identified according to KDIGO (Kidney Disease Improving Global Outcomes) 2012 guidelines.

Results

A total of 28 patients were recruited; among them 23 agreed to be part of the study, of whom 18 received CisPt and 5 carbo- or oxaliplatin. Of the 18 CisPt patients, 12 had a preexisting CKD. Sixteen AKI episodes were observed in 13 patients receiving CisPt with a pejorative evolution in seven cases (partial recovery of the renal function); a transient but dramatic increase in urinary biomarkers was observed 3 h after chemotherapy initiation, whereas plasma creatinine rise appeared 72 h after the end of CisPt treatment. Identified precipitating factors included: dehydration due to lack of fluid intake or diuretic use, exposure to high CisPt doses, regular use of nonsteroidal anti-inflammatory drugs and/or iodinated contrast agents and sepsis.

Conclusion

Even if numerous precipitating factors could be avoided, the monitoring of urinary markers seemed helpful for the early detection of subclinical AKI induced during CisPt chemotherapy.

Urinary NGAL for the diagnosis of the renal injury from multiple myeloma

OBJECTIVES

Neutrophil gelatinase-associated lipocalin (NGAL) has been proved as a sensitive biomarker in acute and chronic renal injury. Renal impairment is a common complication of multiple myeloma (MM). We attempt to assess the value of NGAL for the early and accurate diagnosis of renal injury in MM patients.

METHODOLOGY

Forty-five MM patients with CKD stage I to V(MM-renal group), 20 MM patients with normal kidney function (MM-non-renal group), and 37 healthy volunteers (healthy control) were compared for serum and urinary NGAL and other renal injury biomarkers (Creatinine[CRE]; Cystatin-C [CysC]; N-acetyl-beta-D-glucosaminidase [NAG]). Other biomarkers reflect the inflammation and tumor burden like high-sensitivity C-reactive protein(hs-CRP) and urine free light chain were also detected.

RESULTS

Among the biomarkers of renal injury, the assessment of serum CysC, CRE and NGAL was a reliable tool to distinguish MM-renal from MM-non-renal. Both serum and urinary NGAL levels were higher in MM-renal patients than in MM-non-renal or healthy controls (187.10 (45.60-699.60) vs 136.70 (47.70-216.50) vs 117.7 (69.3-192.3), P< 0.01; 37.50 (6.30-412.10) vs 18.00 (0.50-66.50) vs 11.2 (0.9-69.1), P< 0.01). Univariate analysis showed that both serum (Odds Ratio = 1.009; 95%CI 1.002-1.017; P= 0.018) and urinary NGAL (Odds Ratio = 1.038; 95%CI 1.003-1.073; P= 0.031) as well as serum CysC (Odds Ratio = 9.875; 95%CI 1.685-57.882; P= 0.011) were strong predictors for the risk of renal injury in MM patients. Moreover, the urinary NGAL level was negatively correlated with estimated glomerular filtration rate (eGFR) (r= -0.586, P= 0.00003) and has a tendency towards positive correlation with urine free light chain (r = 0.235, P = 0.124) and hs-CRP (r = 0.379, P = 0.074).

CONCLUSIONS

The present study demonstrated that urinary NGAL was not superior to serum NGAL in distinguishing MM-renal group from MM-non-renal group. And it could be considered an independent predictor of renal injury from multiple myeloma reflecting active kidney damage, tumor burden, and inflammation.

Does remifentanil attenuate renal ischemia-reperfusion injury better than dexmedetomidine in rat kidney?

Background

Ischemia–reperfusion (I/R) injury is a common cause of patient morbidity and mortality in the perioperative period. Patients undergoing long-lasting, abdominal, and urogenital surgeries with risk factors such as advanced age, peripheral artery disease, diabetes mellitus, renovascular disease, and congestive heart failure are candidates for acute kidney injury (AKI) due to impaired renal perfusion and decreased functional renal reserve. Pharmacological agents with multiple functions and anti-oxidative and anti-inflammation properties may be promising preventative strategies for AKI. Recently, dexmedetomidine (dex) has been postulated to have renoprotective effects.

Objectives

We aimed to investigate the protective effects of an intravenous anesthetic remifentanil in renal I/R injury in the rat in comparison with dex.

Materials and methods

A total of 30 Sprague Dawley adult rats were randomly assigned into five groups: the control group (group C, n=6), the sham group (group Sh, n=6, saline-infused rats without I/R injury), the saline group (group S, n=6, saline-infused rats with I/R injury), the remifentanil-treated group (group REM, n=6), and the dexmedetomidine-treated group (group DEX, n=6). The infusions (saline, remifentanil, and dex) were started after anesthesia induction and right nephrectomy and continued until the end of the surgical procedure. In I/R injury groups, the left renal artery and vein were occluded together by a clamp for 30 minutes and reperfusion lasted for 30 minutes. The rats were sacrificed after reperfusion, and the left kidney tissue was harvested. Blood samples were drawn from all animals to evaluate plasma neutrophil gelatinase-associated lipocalin (NGAL) at the beginning, 15 minutes after ischemia, 15 minutes after reperfusion, and 6 hours after the surgical procedure (T0, T1, T2, and T3, respectively).

Results

The plasma NGAL levels exhibited increase at T1, T2, and T3 compared to the levels at T0 in group S (P<0.05). In group REM, there was a significant increase in plasma NGAL levels at T3 in comparison to those at T0, T1, and T2. The plasma NGAL levels at T2 in group S were significantly higher than those at T2 in group DEX (P<0.05). The groups S and REM showed significantly higher plasma NGAL levels at T3 compared to those at T0 (P<0.05). Upon histological examination, there was no difference among the study groups when left kidneys were evaluated (P>0.05).

Conclusion

The NGAL levels and histopathological findings reflected protection by dex against renal I/R injury. However, the same exact results could not be mentioned for remifentanil depending on our study results.

Plasma neutrophil gelatinase-associated lipocalin: a marker of acute pyelonephritis in children

OBJECTIVES

This study was designed to compare the diagnostic accuracy of plasma neutrophil gelatinase-associated lipocalin (NGAL) with procalcitonin (PCT), C-reactive protein (CRP), and white blood cells (WBCs) for predicting acute pyelonephritis (APN) in children with febrile urinary tract infections (UTIs).

MATERIALS AND METHODS

In total, 138 children with febrile UTIs (APN 59, lower UTI 79) were reviewed retrospectively. Levels of NGAL, PCT, CRP, and WBCs in blood were measured on admission. The diagnostic accuracy of the biomarkers was investigated. Independent predictors of APN were identified by multivariate logistic regression analysis.

RESULTS

Receiver operating curve (ROC) analyses showed good diagnostic profiles of NGAL, PCT, CRP, and WBCs for identifying APN [area under the curve (AUC) 0.893, 0.855, 0.879, and 0.654, respectively]. However, multivariate analysis revealed only plasma NGAL level was an independent predictor of APN (P = 0.006). At the best cutoff values of all examined biomarkers for identifying APN, sensitivity (86 %), specificity (85 %), positive predictive value (81 %), and negative predictive value (89 %) of plasma NGAL levels were the highest. The optimal NGAL cutoff value was 117 ng/ml. The positive likelihood ratio [odds ratio (OR) 5.69, 95 % confidence interval (CI) 3.56-8.78], and negative likelihood ratio (OR 0.16, 95 % CI 0.08-0.29) of plasma NGAL for APN diagnosis also showed it seemed to be more accurate than serum PCT, CRP, and WBCs.

CONCLUSION

Plasma NGAL can be more useful than serum PCT, CRP, and WBC levels for identifying APN in children with febrile UTIs.

Perspective on Clinical Application of Biomarkers in AKI

Several biomarkers of renal injury have been identified but the utility of these biomarkers is largely confined to research studies, whereas widespread clinical applicability is limited. This is partly because the use of serum creatinine as the comparator has several limitations and restricts the full interpretation of biomarker performance. To highlight the potential for clinical application of biomarkers, the most pertinent biomarker data are summarized here, using clinically relevant scenarios in which biomarkers could assist with diagnostic and management dilemmas. The paradigms proposed in this review aim to enhance the clinical diagnosis, management, and prognosis of AKI through the combined use of available clinical markers and novel inflammatory, injury, and repair biomarkers.

Urinary Neutrophil Gelatinase-associated Lipocalin in the evaluation of Patent Ductus Arteriosus and AKI in Very Preterm Neonates: a cohort study

Background

A patent ductus arteriosus (PDA) is frequently found in very preterm neonates and is associated with increased risk of morbidity and mortality. A shunt across a PDA can result in an unfavorable distribution of the cardiac output and may in turn result in poor renal perfusion. Urinary Neutrophil Gelatinase-associated Lipocalin (U-NGAL) is a marker of renal ischemia and may add to the evaluation of PDA. Our primary aim was to investigate if U-NGAL is associated with PDA in very preterm neonates. Secondary, to investigate whether U-NGAL and PDA are associated with AKI and renal dysfunction evaluated by fractional excretion of sodium (FENa) and urine albumin in a cohort of very preterm neonates.

Methods

A cohort of 146 neonates born at a gestational age less than 32 weeks were consecutively examined with echocardiography for PDA and serum sodium, and urine albumin and sodium were measured on postnatal day 3 and U-NGAL and serum creatinine day 3 and 6. AKI was defined according to modified neonatal Acute Kidney Injury Network (AKIN) criteria. The association between U-NGAL and PDA was investigated. And secondly we investigated if PDA and U-NGAL was associated with AKI and renal dysfunction.

Results

U-NGAL was not associated with a PDA day 3 when adjusted for gestational age and gender. A PDA day 3 was not associated with AKI when adjusted for gestational age and gender; however, it was associated with urine albumin. U-NGAL was not associated with AKI, but was found to be associated with urine albumin and FENa.

Conclusions

Based on our study U-NGAL is not considered useful as a diagnostic marker to identify very preterm neonates with a PDA causing hemodynamic changes resulting in early renal morbidity. The interpretation of NGAL in preterm neonates remains to be fully elucidated.

Early kidney damage induced by subchronic exposure to PM2.5 in rats

BACKGROUND

Particulate matter exposure is associated with respiratory and cardiovascular system dysfunction. Recently, we demonstrated that fine particles, also named PM_2.5, modify the expression of some components of the angiotensin and bradykinin systems, which are involved in lung, cardiac and renal regulation. The endocrine kidney function is associated with the regulation of angiotensin and bradykinin, and it can suffer damage even as a consequence of minor alterations of these systems. We hypothesized that exposure to PM_2.5 can contribute to early kidney damage as a consequence of an angiotensin/bradykinin system imbalance, oxidative stress and/or inflammation.

RESULTS

After acute and subchronic exposure to PM_2.5, lung damage was confirmed by increased bronchoalveolar lavage fluid (BALF) differential cell counts and a decrease of surfactant protein-A levels. We observed a statistically significant increment in median blood pressure, urine volume and water consumption after PM_2.5 exposure. Moreover, increases in the levels of early kidney damage markers were observed after subchronic PM_2.5 exposure: the most sensitive markers, β-2-microglobulin and cystatin-C, increased during the first, second, sixth and eighth weeks of exposure. In addition, a reduction in the levels of specific cytokines (IL-1β, IL-6, TNF-α, IL-4, IL-10, INF-γ, IL-17a, MIP-2 and RANTES), and up-regulated angiotensin and bradykinin system markers and indicators of a depleted antioxidant response, were also observed. All of these effects are in concurrence with the presence of renal histological lesions and an early pro-fibrotic state.

CONCLUSION

Subchronic exposure to PM_2.5 induced an early kidney damage response that involved the angiotensin/bradykinin systems as well as antioxidant and immune imbalance. Our study demonstrates that PM_2.5 can induce a systemic imbalance that not only affects the cardiovascular system, but also affects the kidney, which may also overall contribute to PM-related diseases.

Neutrophil Gelatinase-Associated Lipocalin, Fibroblast Growth Factor 23, and Soluble Klotho in Long-Term Kidney Donors

Background

The best treatment for end-stage renal disease (ESRD) is kidney transplantation. Twenty-seven percent of transplantations in Norway are from living donors. Recent studies have shown an increased risk of ESRD and increased mortality in donors. The aim of this study was to determine if the levels of the new biomarkers neutrophil gelatinase-associated lipocalin (NGAL), soluble Klotho (sKlotho), and fibroblast growth factor 23 (FGF23) are changed in kidney donors with normal kidney function defined as an estimated glomerular filtration rate (eGFR) >60 ml/min/1.73 m² compared to patients with chronic kidney disease (CKD) stages 3-5 and healthy controls.

Methods

This is a cross-sectional, observational, single-center study including 35 kidney donors with an eGFR ≥60 ml/min/1.73 m² 5 years after donation, 22 patients with CKD stage 3 (eGFR 30-59 ml/min/1.73 m²), 18 patients with CKD stage 4 (eGFR 15-29 ml/min/1.73 m²), 20 patients with CKD stage 5 (eGFR <15 ml/min/1.73 m²), and 35 controls comparing levels of biomarkers in long-term kidney donors with those in CKD patients and healthy controls.

Results

The level of log NGAL was significantly higher in donors than in healthy controls (2.02 ± 0.10 vs. 1.89 ± 0.10 ng/ml; p < 0.001), and the level increased with declining kidney function. The log FGF23 level was nonsignificantly higher in donors than in controls, but it significantly increased with declining kidney function. The log sKlotho levels were significantly lower in patients with CKD stages 4 and 5 than in controls, but no difference was revealed between controls and donors.

Conclusion

Kidney donors have significantly higher levels of NGAL than healthy controls after a median of 15 years (range 5-38). NGAL could be a valuable diagnostic marker in the future. FGF23 and sKlotho were not significantly different between donors and controls.

The Associations of Blood Kidney Injury Molecule-1 and Neutrophil Gelatinase-Associated Lipocalin with Progression from CKD to ESRD

BACKGROUND AND OBJECTIVES

Elevated levels of urinary kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin are associated with negative outcomes in CKD. Our study aimed to explore the prognostic accuracy of blood levels of kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin for progression to ESRD, major adverse cardiovascular events, and death in a large cohort of adult patients with all-cause nondialysis-dependent CKD stages 3-5. We considered whether these factors improve prediction in relation to traditional biomarkers and clinical parameters.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin were measured on baseline plasma samples from 1982 patients who were recruited to the Chronic Renal Insufficiency Standards Implementation Study between the start of June of 2002 and the start of June of 2013. Associations with study end points were assessed using Cox regression models, receiver operator characteristic curve analyses, and reclassification statistics.

RESULTS

Over a median follow-up of 29.5 months (interquartile range, 14.9-53.5), 21.6% of patients progressed to ESRD, 27% died, and 6.6% suffered a major adverse cardiovascular event. Higher blood levels of kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin were independently associated with a greater risk for ESRD (hazard ratio, 1.25; 95% confidence interval, 1.10 to 1.43; P<0.001 and hazard ratio, 1.35; 95% confidence interval, 1.14 to 1.59; P≤0.001, respectively, per 1 SD higher biomarker concentration). There was no association with risk for cardiovascular events or death. The addition of biomarkers to our baseline risk model of traditional clinical characteristics and laboratory parameters did not significantly improve model discrimination or risk reclassification.

CONCLUSIONS

In patients with moderate to severe CKD, kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin blood levels are independent risk factors for progression to ESRD. Additional studies are needed to establish the utility and cost-effectiveness of these novel biomarkers in the clinical setting.

Associations Between Neutrophil Gelatinase Associated Lipocalin, Neutrophil-to-Lymphocyte Ratio, Atrial Fibrillation and Renal Dysfunction in Chronic Heart Failure

BACKGROUND Atrial fibrillation (AF) and renal dysfunction are two common comorbidities in patients with chronic heart failure with reduced ejection fraction (HFrEF). This study evaluated the effect of permanent AF on renal function in HFrEF and investigated the associations of atrial fibrillation, neutrophil gelatinase-associated lipocalin (NGAL), and neutrophil-to-lymphocyte ratio (NLR) with adverse clinical outcome. MATERIAL AND METHODS Serum NGAL levels measured by ELISA and NLR were compared between patients with sinus rhythm (HFrEF-SR, n=68), with permanent AF (HFrEF-AF, n=62), and a healthy control group (n=50). RESULTS Mean eGFR levels were significantly lower, and NLR and NGAL levels were significantly higher in the HFrEF patients than in the control patients but the difference between HFrEF-SR and HFrEF-AF was not statistically significant (NGAL: 95 ng/mL in HFrEF-SR, 113 ng/mL in HFrEF-AF and 84 ng/mL in the control group; p<0.001). Independent associates of baseline eGFR were age, hemoglobin, NLR, triiodothyronine, and pulmonary artery systolic pressure. In a mean 16 months follow-up, adverse clinical outcome defined as progression of kidney dysfunction and composite of all-cause mortality and re-hospitalization were not different between HFrEF-SR and HFrEF-AF patients. Although NGAL was associated with clinical endpoints in the univariate analysis, Cox regression analysis showed that independent predictors of increased events were the presence of signs right heart failure, C-reactive protein, NLR, triiodothyronine, and hemoglobin. In ROC analysis, a NLR >3 had a 68% sensitivity and 75% specificity to predict progression of kidney disease (AUC=0.72, 95% CI 0.58-0.85, p=0.001). CONCLUSIONS Presence of AF in patients with HFrEF was not an independent contributor of adverse clinical outcome (i.e., all-cause death, re-hospitalization) or progression of renal dysfunction. Renal dysfunction in HFrEF was associated with both NLR and NGAL levels, but systemic inflammation reflected by NLR seemed to be a more important determinant of progression of kidney dysfunction.

Expression and Function of Interleukin-1β-Induced Neutrophil Gelatinase-Associated Lipocalin in Renal Tubular Cells

Acute kidney injury (AKI) is characterized by a sudden loss of renal function. Early recognition of AKI, especially in critically ill patients, is essential for adequate therapy. Currently, neutrophil gelatinase-associated lipocalin (NGAL) is considered to be an effective biomarker of AKI; however, the regulation of its expression and function in renal tubular cells remains unclear. In this study, we investigated the regulation of the expression and function of NGAL in IL-1β-treated Madin–Darby canine kidney (MDCK) cells as a model of renal tubular cells. IL-1β induced a disturbance in the localization of E-cadherin and zonaoccludin-1 (ZO-1). The transepithelial electrical resistance (TER) also decreased 5 days after IL-1β treatment. IL-1β induced NGAL mRNA expression and protein secretion in a time- and dose-dependent manner, which occurred faster than the decrease in TER. In the presence of ERK1/2 and p38 inhibitors, IL-1β-induced NGAL mRNA expression and protein secretion were significantly attenuated. In the presence of recombinant NGAL, IL-1β-induced disturbance in the localization of E-cadherin and ZO-1 was attenuated, and the decrease in TER was partially maintained. These results suggest that NGAL can be used as a biomarker for AKI and that it functions as a protector from AKI.

Cardioprotection and lifespan extension by the natural polyamine spermidine

Aging is associated with an increased risk of cardiovascular disease and death. Here we show that oral supplementation of the natural polyamine spermidine extends the lifespan of mice and exerts cardioprotective effects, reducing cardiac hypertrophy and preserving diastolic function in old mice. Spermidine feeding enhanced cardiac autophagy, mitophagy and mitochondrial respiration, and it also improved the mechano-elastical properties of cardiomyocytes in vivo, coinciding with increased titin phosphorylation and suppressed subclinical inflammation. Spermidine feeding failed to provide cardioprotection in mice that lack the autophagy-related protein Atg5 in cardiomyocytes. In Dahl salt-sensitive rats that were fed a high-salt diet, a model for hypertension-induced congestive heart failure, spermidine feeding reduced systemic blood pressure, increased titin phosphorylation and prevented cardiac hypertrophy and a decline in diastolic function, thus delaying the progression to heart failure. In humans, high levels of dietary spermidine, as assessed from food questionnaires, correlated with reduced blood pressure and a lower incidence of cardiovascular disease. Our results suggest a new and feasible strategy for protection against cardiovascular disease.

Urinary neutrophil gelatinase-associated lipocalin is an early predictor of acute kidney injury in premature infants

Urinary neutrophil gelatinase-associated lipocalin (uNGAL) is produced in response to tubular epithelial injury and is a biomarker of tubulointerstitial injury. The aim of the present study was to examine whether acute kidney injury (AKI) could be predicted by measuring uNGAL in very low-birth weight (VLBW) infants. Forty VLBW infants with birthweight below 1,500 g were enrolled in the present study. uNGAL and serum creatinine (sCre) were measured daily from postnatal days 0 to 8. Infants with sCre ≥1.2 mg/dl were diagnosed with AKI. The relationship of uNGAL with sCre was measured on the day after uNGAL measurement (next-day sCre) was examined. The results showed that 16 infants had sCre ≥1.2 mg/dl in this period. Logistic regression analysis revealed that uNGAL on postnatal days 2, 3, 4, 5 and 6 was correlated with next-day sCre (P<0.05). uNGAL corrected by urinary Cre (uCre) (uNGAL/uCre) was only correlated with an increase in next-day sCre on postnatal days 5 and 6 (P<0.05). For the logistic analysis, subjects with high and low uNGAL levels based on the median value for each day, uNGAL on postnatal days 2, 3 and 6 in the high uNGAL group was correlated with an increase in next-day sCre. Thus, AKI may be predicted by measuring uNGAL in VLBW infants. This measurement was non-invasive, and is potentially useful for the evaluation of renal function in VLBW infants.

A randomised controlled trial evaluating renal protective effects of selenium with vitamins A, C, E, verapamil, and losartan against extracorporeal shockwave lithotripsy-induced renal injury

OBJECTIVE

To evaluate the protective effects of selenium with vitamins A, C and E (selenium ACE, i.e. antioxidants), verapamil (calcium channel blocker), and losartan (angiotensin receptor blocker) against extracorporeal shockwave lithotripsy (ESWL)-induced renal injury.

PATIENTS AND METHODS

A randomised controlled trial was conducted between August 2012 and February 2015. Inclusion criteria were adult patients with a single renal stone (<2 cm) suitable for ESWL. Patients with diabetes, hypertension, congenital renal anomalies, moderate or marked hydronephrosis, or preoperative albuminuria (>300 mg/L) were excluded. ESWL was performed using the electromagnetic DoLiS lithotripter. Eligible patients were randomised into one of four groups using sealed closed envelopes: Group1, control; Group 2, selenium ACE; Group 3, losartan; and Group 4, verapamil. Albuminuria and urinary neutrophil gelatinase-associated lipocalin (uNGAL) were estimated after 2-4 h and 1 week after ESWL. The primary outcome was differences between albuminuria and uNGAL. Dynamic contrast-enhanced magnetic resonance imaging was performed before ESWL, and at 2-4 h and 1 week after ESWL to compare changes in renal perfusion.

RESULTS

Of 329 patients assessed for eligibility, the final analysis comprised 160 patients (40 in each group). Losartan was the only medication that showed significantly lower levels of albuminuria after 1 week (P < 0.001). For perfusion changes, there was a statistically significant decrease in the renal perfusion in patients with obstructed kidneys in comparison to before ESWL (P = 0.003). These significant changes were present in the control or antioxidant group, whilst in the losartan and verapamil groups renal perfusion was not significantly decreased.

CONCLUSIONS

Losartan was found to protect the kidney against ESWL-induced renal injury by significantly decreasing post-ESWL albuminuria. Verapamil and losartan maintained renal perfusion in patients with post-ESWL renal obstruction.

Synergistic effect of apoptosis and necroptosis inhibitors in cisplatin-induced nephrotoxicity

Necroptosis is a nonapoptotic cell death pathway. We aim to study the effect of necrostatin-1 (a specific necroptosis inhibitor) in cisplatin-induced injury. We analyzed the effect of the combined use of inhibitors of apoptosis (z-vad) and necroptosis (necrostatin-1) in acute kidney injury by cisplatin in human proximal tubule cells. Our results showed moderate effectiveness in cytoprotection after treatment with z-vad. But the concomitant use of inhibitors (z-vad and necrostatin-1) presented synergistic and additive protection. The present study analyzed the caspase-3 activity and we observed a significant decrease in the group treated with z-vad and cisplatin. However we did not observe changes in the group treated with both inhibitors (z-vad and necrostatin-1) and cisplatin. Thus, demonstrating that necroptosis is a caspase-independent mechanism. We also analyzed the effect of necrostatin-1 in vivo model. C57BL/6 mice were treated with cisplatin and/or inhibitors. The concomitant use of inhibitors (z-vad and necrostatin-1) recovered renal function and decreased levels of urinary Ngal. Additionally, we analyzed the expression of RIP-1, a specific marker for necroptosis. In animals treated with cisplatin and z-VAD levels of RIP-1 were higher. This result reinforces that necroptosis occurs only in conditions where apoptosis was blocked. However, the use of both inhibitors (z-vad and necrostatin-1) provided additional protection. In conclusion, our study has a significant potential to show in vitro and in vivo protection obtained by necrostatin-1. Therefore, our results suggest that necroptosis may be an important mechanism of cell death after kidney injury.

Urinary Markers of Tubular Injury in HIV-Infected Patients

Renal disease is a common complication of HIV-infected patients, associated with increased risk of cardiovascular events, progression to AIDS, AIDS-defining illness, and mortality. Early and accurate identification of renal disease is therefore crucial to improve patient outcomes. The use of serum creatinine, along with proteinuria, to detect renal involvement is essentially to screen for markers of glomerular disease and may not be effective in detecting earlier stages of renal injury. Therefore, more sensitive and specific markers are needed in order to early identify HIV-infected patients at risk of renal disease. This review article summarizes some new and important urinary markers of tubular injury in HIV-infected patients and their clinical usefulness in the renal safety follow-up of TDF-treated patients.

Increase of Total Nephron Albumin Filtration and Reabsorption in Diabetic Nephropathy

The amount of albumin filtered through the glomeruli and reabsorbed at the proximal tubules in normal and in diabetic kidneys is debated. The megalin/cubilin complex mediates protein reabsorption, but genetic knockout of megalin is perinatally lethal. To overcome current technical problems, we generated a drug-inducible megalin-knockout mouse line, megalin(lox/lox);Ndrg1-CreER^T2 (iMegKO), in which megalin expression can be shut off at any time by administration of tamoxifen (Tam). Tam administration in adult iMegKO mice decreased the expression of renal megalin protein by 92% compared with that in wild-type C57BL/6J mice and almost completely abrogated renal reabsorption of intravenously injected retinol-binding protein. Furthermore, urinary albumin excretion increased to 175 μg/d (0.46 mg albumin/mg creatinine) in Tam-treated iMegKO mice, suggesting that this was the amount of total nephron albumin filtration. By comparing Tam-treated, streptozotocin-induced diabetic iMegKO mice with Tam-treated nondiabetic iMegKO mice, we estimated that the development of diabetes led to a 1.9-fold increase in total nephron albumin filtration, a 1.8-fold increase in reabsorption, and a significant reduction in reabsorption efficiency (86% efficiency versus 96% efficiency in nondiabetic mice). Insulin treatment normalized these abnormalities. Akita;iMegKO mice, another model of type 1 diabetes, showed equivalent results. Finally, nondiabetic iMegKO mice had a glomerular sieving coefficient of albumin of 1.7×10^-5, which approximately doubled in diabetic iMegKO mice. This study reveals actual values and changes of albumin filtration and reabsorption in early diabetic nephropathy in mice, bringing new insights to our understanding of renal albumin dynamics associated with the hyperfiltration status of diabetic nephropathy.

Urinary Markers of Tubular Injury in Early Diabetic Nephropathy

Diabetic nephropathy (DN) is a common and serious complication of diabetes associated with adverse outcomes of renal failure, cardiovascular disease, and premature mortality. Early and accurate identification of DN is therefore of critical importance to improve patient outcomes. Albuminuria, a marker of glomerular involvement in early renal damage, cannot always detect early DN. Thus, more sensitive and specific markers in addition to albuminuria are needed to predict the early onset and progression of DN. Tubular injury, as shown by the detection of tubular injury markers in the urine, is a critical component of the early course of DN. These urinary tubular markers may increase in diabetic patients, even before diagnosis of microalbuminuria representing early markers of normoalbuminuric DN. In this review we summarized some new and important urinary markers of tubular injury, such as neutrophil gelatinase associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), liver-type fatty acid binding protein (L-FABP), N-acetyl-beta-glucosaminidase (NAG), alpha-1 microglobulin (A1M), beta 2-microglobulin (B2-M), and retinol binding protein (RBP) associated with early DN.

Kidney injury molecule-1 and microalbuminuria levels in Zambian population: biomarkers of kidney injury

Introduction

Kidney injury affects renal excretion of plasma analytes and metabolic waste products with grave pathologic consequences. Early detection, thus of kidney injury is essential for injury specific intervention that may avert permanent renal damage and delay progression of kidney injury. We aimed to evaluate Kidney Injury Molecule-1 (KIM-1) and Microalbuminuria (MAU), as biomarkers of kidney injury, in comparison with creatinine.

Methods

We compared the levels of urine MAU, urine KIM-1 and other plasma biochemical tests in specimens from 80 individuals with and without kidney disease.

Results

We found no difference in KIM-1 levels between the kidney disease group (2.82± 1.36ng/mL) and controls (3.29 ± 1.14ng/mL), p = 0.122. MAU was higher in participants with kidney disease (130.809± 84.744 µg/mL) than the controls (15.983± 20.442µg/mL), p ?0.001. KIM-1 showed a weak negative correlation with creatinine (r = -0.279, p = 0.09), whereas MAU was positively correlated with creatinine in participants with kidney disease with statistical significance (r = 0.556, p = 0.001).

Conclusion

The study demonstrated that in Zambian setting MAU and creatinine are sensitive biomarkers in the diagnosis of kidney damage. We moreover propose further evaluation of KIM-1 as a biomarker of kidney injury.

Neutrophil gelatinase-associated lipocalin as a biomarker of disease progression in patients with chronic kidney disease

Chronic kidney disease (CKD) is associated with early mortality, decreased quality of life and increased health care expenditures. The aim of this study was to determine whether or not urinary NGAL (uNGAL) level is associated with renal damage and kidney disease progression in patients with CKD and to evaluate the predictive value of uNGAL in progression of CKD. Totally, 91 cases of CKD stage II, III, IV, and 50 age-matched healthy controls were enrolled. The follow-up end-point was 18 months; end-point of the study was progression to an estimated glomerular filtration rate (eGFR) of <15 ml/min and/or CKD stage V. Forty-five cases (49.4%) were progressors and 46 were nonprogressors. uNGAL levels were significantly higher in CKD subjects as compared to healthy controls (log 1.09 ± 0.22 μg/ml in controls versus log 1.22 ± 2.08 μg/ml in stage II, log 3.34 ± 2.74 μg/ml in stage III and log 3.70 ± 0.18 μg/ml in stage IV). Univariate Cox proportional hazards model showed that only eGFR (hazard ratio [HR]: 0.95; 95% confidence interval [CI]: 0.93–0.96; P < 0.001) and uNGAL (HR: 1.11; 95% CI: 1.01–1.20; P < 0.001) were significantly associated with end-point of CKD stage V, but multiple Cox proportional regression model showed significant association of uNGAL (HR: 1.11; 95% CI: 1.01–1.20; P < 0.001) and eGFR (HR: 0.962, 95% CI: 0.95–0.98; P < 0.001) with end-point of CKD stage V. This suggests that uNGAL would not be a simple surrogate index of baseline eGFR, but a marker of CKD progression beyond the information provided by eGFR estimation.

Plasma Neutrophil Gelatinase-Associated Lipocalin Reflects Both Inflammation and Kidney Function in Patients with Myocardial Infarction

BACKGROUND/AIMS

Neutrophil gelatinase-associated lipocalin (NGAL) has emerged as a marker for acute kidney injury and cardiovascular outcome. However, the relative importance of inflammation versus kidney function on plasma NGAL levels is uncertain, making the interpretation of plasma NGAL unclear. Accordingly, we investigated the relationship between plasma NGAL, inflammation and kidney function in patients with myocardial infarction (MI).

METHODS

We prospectively included 584 patients with acute ST-segment elevation MI (STEMI) treated with primary percutaneous coronary intervention (PCI) from 2006 to 2008. Blood samples were drawn immediately before PCI. Additionally, we included 42 patients who had 4 blood samples drawn before and after PCI. Plasma NGAL was measured using a time-resolved immunofluorometric assay. Cross-sectional analyses were performed in these two single-center, prospective study cohorts.

RESULTS

Estimated glomerular filtration rate (eGFR) was associated significantly more strongly with plasma NGAL when eGFR was abnormal compared to normal eGFR: a decrease in eGFR of 10 ml/min was associated with an increase in NGAL of 27% (18-36%) versus 4% (1-7%), respectively (p < 0.001). Leukocyte count and C-reactive protein were the main determinants of plasma NGAL in patients with normal eGFR, whereas eGFR was the main determinant at reduced kidney function.

CONCLUSIONS

eGFR determines the association of NGAL with either inflammation or kidney function; in patients with normal eGFR, plasma NGAL reflects inflammation but when eGFR is reduced, plasma NGAL reflects kidney function, highlighting the dual perception of plasma NGAL. From a clinical perspective, eGFR may be used to guide the interpretation of elevated NGAL levels in patients with STEMI.

Assessment of Neutrophil Gelatinase-Associated Lipocalin (NGAL) and Retinol-Binding Protein 4 (RBP4) in Type 2 Diabetic Patients with Nephropathy

Diabetic nephropathy (DN) is one of the most serious microvascular complications of diabetes. The study aims to evaluate the diagnostic value of serum neutrophil gelatinase-associated lipocalin (NGAL) and retinol-binding protein 4 (RBP4) as biomarkers for early detection of nephropathy in type 2 diabetic patients. The current study was performed on 150 type 2 diabetic patients. These patients were classified into three equal groups according to their albumin/creatinine ratio (ACR), including patients with normoalbuminuria (ACR <30 mg/g creatinine), patients with microalbuminuria (ACR = 30-300 mg/g creatinine), and patients with macroalbuminuria (ACR >300 mg/g creatinine). Fifty apparently healthy subjects matching the same age and socioeconomic status with diabetic subjects were selected as a control group. The plasma glucose, insulin, glycosylated hemoglobin (HbA1c), homeostasis model assessment of insulin resistance (HOMA-IR), lipid profile, urea, creatinine, cystatin C, glomerular filtration rate (GFR), NGAL, and RBP4 were measured in the studied groups. Significantly elevated NGAL and RBP4 levels were observed in micro- and macroalbuminuric diabetic groups when compared to the control and normoalbuminuric diabetic groups. NGAL and RBP4 were found to correlate positively with duration of diabetes, systolic and diastolic blood pressure, glucose, HbA1c, HOMA-IR, triacylglycerol, and ACR, but correlate inversely with GFR in DN groups. Receiver operating characteristic curves revealed that for early detection of DN, the best cutoff values to discriminate DN and diabetic without nephropathy groups were 91.5 ng/mL for NGAL with 87% sensitivity, 74% specificity, and area under the curve (AUC) = 0.881; 24.5 ng/mL for RBP4 with 84% sensitivity, 90% specificity, and AUC = 0.912; and 37.5 mg/g creatinine for ACR with 89% sensitivity, 72% specificity, and AUC = 0.819. RBP4 is more specific (90% specificity) than NGAL (74% specificity) and ACR (72% specificity). Therefore, RBP4 marker may serve as a tool to follow-up clinical monitoring of the development and progression of DN.

Renal function in children treated for central nervous system malignancies

AIM

The aim of the study was to evaluate renal function and to assess the usefulness of the following nephrotoxicity markers: cystatin C (CYS C), beta-2 microglobulin (B2MG) and neutrophil gelatinase-associated lipocalin (NGAL) in 38 (18 girls, 20 boys) children previously treated for central nervous system malignancy.

MATERIAL

Median age at evaluation was 13.7 years (range 2.1-22 years). The mean follow-up time after the completion of chemotherapy was 3.2 years (range 0.16-6.5 years).

RESULTS

Subclinical chronic kidney disease (estimated glomerular filtration rate: eGFR 90-60 ml/min/1.73 m(2)) was found in 22 patients (58 %), while renal insufficiency (eGFR 30-60 ml/min/1.73 m(2)) was found in six children (16 %). It has been demonstrated statistically significant negative correlation between the eGFR and cystatin C concentration (p < 0.0001) and eGFR and beta-2 microglobulin concentration (p < 0.02). Conversely, there was no correlation between eGFR and NGAL. Thirteen children (34 %) developed drug-induced tubulopathy: decreased tubular reabsorption of phosphate (TRP) and renal tubular threshold for phosphate (Tmp/GFR).

CONCLUSION

Children treated for CNS tumours often develop drug-induced chronic renal disease, involving the glomeruli and/or renal tubules. Cystatin C and beta-2 microglobulin seemed to be good markers for chronic kidney damage in these patients, which is probably not true for NGAL.

Comparison of Plasma and Urine Biomarker Performance in Acute Kidney Injury

Background

New renal biomarkers measured in urine promise to increase specificity for risk stratification and early diagnosis of acute kidney injury (AKI) but concomitantly may be altered by urine concentration effects and chronic renal insufficiency. This study therefore directly compared the performance of AKI biomarkers in urine and plasma.

Methods

This single-center, prospective cohort study included 110 unselected adults undergoing cardiac surgery with cardiopulmonary bypass between 2009 and 2010. Plasma and/or urine concentrations of creatinine, cystatin C, neutrophil gelatinase-associated lipocalin (NGAL), liver fatty acid-binding protein (L-FABP), kidney injury molecule 1 (KIM1), and albumin as well as 15 additional biomarkers in plasma and urine were measured during the perioperative period. The primary outcome was AKI defined by AKIN serum creatinine criteria within 72 hours after surgery.

Results

Biomarkers in plasma showed markedly better discriminative performance for preoperative risk stratification and early postoperative (within 24h after surgery) detection of AKI than urine biomarkers. Discriminative power of urine biomarkers improved when concentrations were normalized to urinary creatinine, but urine biomarkers had still lower AUC values than plasma biomarkers. Best diagnostic performance 4h after surgery had plasma NGAL (AUC 0.83), cystatin C (0.76), MIG (0.74), and L-FAPB (0.73). Combinations of multiple biomarkers did not improve their diagnostic power. Preoperative clinical scoring systems (EuroSCORE and Cleveland Clinic Foundation Score) predicted the risk for AKI (AUC 0.76 and 0.71) and were not inferior to biomarkers. Preexisting chronic kidney disease limited the diagnostic performance of both plasma and urine biomarkers.

Conclusions

In our cohort plasma biomarkers had higher discriminative power for risk stratification and early diagnosis of AKI than urine biomarkers. For preoperative risk stratification of AKI clinical models showed similar discriminative performance to biomarkers. The discriminative performance of both plasma and urine biomarkers was reduced by preexisting chronic kidney disease.

Neutrophil Gelatinase Associated Lipocalin (NGAL) in Leptospirosis Acute Kidney Injury: A Multicenter Study in Thailand

AKI is one of the most serious complications of leptospirosis, an important zoonosis in the tropics. Recently, NGAL, one of the novel AKI biomarkers, is extensively studied in various specific settings such as sepsis, cardiac surgery, and radiocontrast nephropathy. In this multicenter study, we aimed to study the role of NGAL as an early marker and an outcome predictor of leptospirosis associated AKI. Patients who presented with clinical suspiciousness of leptospirosis were prospectively enrolled in 9 centers from August 2012 to November 2014. The first day of enrollment was the first day of clinical suspicious leptospirosis. Blood and urine samples were serially collected on the first three days and day 7 after enrollment. We used three standard techniques (microscopic agglutination test, direct culture, and PCR technique) to confirm the diagnosis of leptospirosis. KDIGO criteria were used for AKI diagnosis. Recovery was defined as alive and not requiring dialysis during hospitalization or maintaining maximum KDIGO stage at hospital discharge. Of the 221 recruited cases, 113 cases were leptospirosis confirmed cases. Thirty seven percent developed AKI. Median uNGAL and pNGAL levels in those developing AKI were significantly higher than in patients not developing AKI [253.8 (631.4) vs 24.1 (49.6) ng/ml, p < 0.001] and [1,030 (802.5) vs 192.0 (209.0) ng/ml, p < 0.001], respectively. uNGAL and pNGAL levels associated with AKI had AUC-ROC of 0.91, and 0.92, respectively. Both of urine NGAL and pNGAL level between AKI-recovery group and AKI-non recovery were comparable. From this multicenter study, uNGAL and pNGAL provided the promising result to be a marker for leptospirosis associated AKI. However, both of them did not show the potential role to be the predictor of renal recovery in this specific setting.

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.

Prognostic significance of urinary NGAL in chronic kidney disease

Background

Chronic kidney disease (CKD) is a worldwide public health problem. Recently urinary NGAL (uNGAL) has been proven to be a useful (potentially ideal) biomarker for early detection of CKD. The aim of the present study was to examine the correlation of uNGAL with severity of renal impairment in CKD and to evaluate its prognostic value in these subjects.

Methods

This was a prospective study carried out over a period of 24 months in subjects with CKD due to primary chronic glomerulonephritis. New cases of CKD stage II, III, IV aged between 18 and 65 years were enrolled as per KDIGO (Kidney Disease: Improving Global Outcomes) guidelines 2012. A total of 90 subjects completed the study up to the end-point. The primary follow-up end-point was 18 months, or decreased glomerular filtration rate of less than 15 mL/min. Secondary follow-up end-point was the number of subjects who expired during this period.

Results

Multiple regression model of estimated glomerular filtration rate showed significant associations with log uNGAL (β=0.38, P<0.001), Ca×PO4 (β=0.60, P<0.001), hemoglobin (β=0.37, P<0.001), urine protein (β=0.34, P<0.001), serum albumin (β=0.48, P<0.001), and systolic blood pressure (β=0.76, P<0.001). Receiver operator curve for uNGAL considering the progression of CKD showed area under the curve for uNGAL was 0.878 (95% confidence interval: 0.68–0.96). Cut-off value for uNGAL was log 3.5 unit with a sensitivity of 93.08% and specificity of 71.43% for predicting the progression of CKD. Kaplan–Meier survival curve showed that patients with log uNGAL levels <3.51 unit had a survival rate of 71.4% while patients with NGAL level >3.51 unit had a renal survival rate of 14.7%.

Conclusion

Our study result showed that uNGAL has a positive correlation with disease severity which signifies the prognostic importance of uNGAL in CKD.

Renalase and Biomarkers of Contrast-Induced Acute Kidney Injury

BACKGROUND

Contrast-induced acute kidney injury (CI-AKI) remains one of the crucial issues related to the development of invasive cardiology. The massive use of contrast media exposes patients to a great risk of contrast-induced nephropathy and chronic kidney disease development, and increases morbidity and mortality rates. The serum creatinine concentration does not allow for a timely and accurate CI-AKI diagnosis; hence numerous other biomarkers of renal injury have been proposed. Renalase, a novel catecholamine-metabolizing amine oxidase, is synthesized mainly in proximal tubular cells and secreted into urine and blood. It is primarily engaged in the degradation of circulating catecholamines. Notwithstanding its key role in blood pressure regulation, renalase remains a potential CI-AKI biomarker, which was shown to be markedly downregulated in the aftermath of renal injury. In this sense, renalase appears to be the first CI-AKI marker revealing an actual loss of renal function and indicating disease severity.

SUMMARY

The purpose of this review is to summarize the contemporary knowledge about the application of novel biomarkers of CI-AKI and to highlight the potential role of renalase as a functional marker of contrast-induced renal injury.

KEY MESSAGES

Renalase may constitute a missing biochemical link in the mutual interplay between kidney and cardiac pathology known as the cardiorenal syndrome.

Low Serum Neutrophil Gelatinase-associated Lipocalin Level as a Marker of Malnutrition in Maintenance Hemodialysis Patients

Background

Neutrophil gelatinase-associated lipocalin (NGAL or LCN2) is an iron-transporting factor which possesses various activities such as amelioration of kidney injury and host defense against pathogens. Its circulating concentrations are elevated in acute and chronic kidney diseases and show a positive correlation with poor renal outcome and mortality, but its clinical significance in maintenance hemodialysis (HD) patients remains elusive.

Methods

Serum NGAL levels were determined by enzyme-linked immunosorbent assay in out-patient, Japanese HD subjects. Their correlation to laboratory findings and morbidity (as development of severe infection or serum albumin reduction) was investigated using linear regression analysis and χ² test.

Results

Pre-dialysis serum NGAL levels in HD patients were elevated by 13-fold compared to healthy subjects (n=8, P<0.001). In a cross-sectional study of 139 cases, serum NGAL concentrations were determined independently by % creatinine generation rate (an indicator of muscle mass, standardized coefficient β=0.40, P<0.001), peripheral blood neutrophil count (β=0.38, P<0.001) and anion gap (which likely reflects dietary protein intake, β=0.16, P<0.05). Iron administration to anemic HD patients caused marked elevation of peripheral blood hemoglobin, serum ferritin and iron-regulatory hormone hepcidin-25 levels, but NGAL levels were not affected. In a prospective study of 87 cases, increase in serum albumin levels a year later was positively associated to baseline NGAL levels by univariate analysis (r=0.36, P<0.01). Furthermore, within a year, patients with the lowest NGAL tertile showed significantly increased risk for marked decline in serum albumin levels (≥0.4 g/dl; odds ratio 5.5, 95% confidence interval 1.5–20.3, P<0.05) and tendency of increased occurrence of severe infection requiring admission (odds ratio 3.1, not significant) compared to the middle and highest tertiles.

Conclusion

Low serum NGAL levels appear to be associated with current malnutrition and also its progressive worsening in maintenance HD patients.

Urinary neutrophil gelatinase-associated lipocalin: potential biomarker for late-onset sepsis

BACKGROUND

To assess the ability of urinary neutrophil gelatinase-associated lipocalin (UNGAL) to discriminate between culture-positive vs. culture-negative late-onset sepsis evaluations.

METHODS

This is a prospective observational study of 136 neonates who underwent ≥1 sepsis evaluation at >72 h of age. Urine was obtained at the time of sepsis evaluation to measure UNGAL concentration. Using generalized estimating equations controlling for gender, gestational and postnatal age, acute kidney injury, and within-patient correlations, pair-wise contrasts between mean log UNGAL concentrations of infants with negative sepsis evaluations vs. culture-positive sepsis and presumed sepsis were assessed. Discrimination characteristics at several UNGAL cutoff concentrations were assessed using receiver-operating characteristic curves.

RESULTS

The predicted mean log UNGAL values of culture-positive sepsis and presumed sepsis vs. negative sepsis evaluations differed significantly (P < 0.001 and P = 0.02, respectively). At a cutoff ≥ 50 ng/ml, UNGAL discriminated between culture-positive sepsis and culture-negative sepsis evaluations with sensitivity = 86%, specificity = 56%, positive predictive value = 41%, negative predictive value = 92%, and number needed to treat = 3.

CONCLUSION

UNGAL is a noninvasive biomarker with high negative predictive value at the time of late-onset sepsis evaluation in neonates and could be a useful adjunct to traditional components of sepsis evaluations.

Plasma neutrophil gelatinase-associated lipocalin predicts acute pyelonephritis in children with urinary tract infections

BACKGROUND

The identification of acute pyelonephritis (APN) is still a challenge.

METHODS

Patients admitted for their first urinary tract infection (UTI) were enrolled. Plasma neutrophil gelatinase-associated lipocalin (NGAL) levels were measured at admittance and after treatment. Laboratory, clinical, and imaging results were compared between children with and without APN.

RESULTS

A total of 123 patients were enrolled (53 APN and 70 lower UTI). After adjusting for age and gender, plasma NGAL levels were higher in the APN group than in the lower UTI group (233 (129-496) ng/ml vs. 71 (50.8-110) ng/ml, P < 0.001). NGAL levels were correlated with the serum levels of leukocytes, C-reactive protein, and creatinine, as well as fever duration (P < 0.05). Multivariable analysis revealed that log-transformed plasma NGAL was an independent predictor of APN (P < 0.05). Receiver operating curve analysis showed a good diagnostic profile of NGAL for identifying APN (area under the curve 0.864) with a best cut-off value of 102.5 ng/ml. The NGAL levels in both two groups decreased after treatment compared to levels before treatment (P < 0.001).

CONCLUSION

Plasma NGAL can be a sensitive predictor for identifying APN and monitoring the treatment response of pediatric UTI.

Neutrophil gelatinase-associated lipocalin combined with delta serum creatinine provides early risk stratification for adverse outcomes after cardiac surgery: a prospective observational study

OBJECTIVES

Novel biomarkers of renal injury appear inconsistent in identifying a creatinine-based diagnosis of acute kidney injury. To be clinically useful, novel acute kidney injury biomarkers should identify patients at increased risk for adverse outcomes that are a consequence of acute kidney injury earlier and with greater utility than conventional creatinine-based metrics. We sought to determine the prognostic utility of both urinary neutrophil gelatinase-associated lipocalin and varying creatinine-based metrics of renal injury at multiple time points associated with cardiac surgery.

DESIGN

Prospective observational study.

SETTING

Academic medical center.

PATIENTS

Six hundred three adults undergoing cardiac surgery.

INTERVENTIONS

Nil.

MEASUREMENTS AND MAIN RESULTS

Urinary neutrophil gelatinase-associated lipocalin was measured at baseline and again less than 1 hour, 3 hours, and 18-24 hours after separation from cardiopulmonary bypass. Creatinine-based metrics included a Kidney Disease: Improving Global Outcomes definition of acute kidney injury through 7 days postoperatively as well as ΔSCr-initial, defined as the incremental change in SCr from baseline to first postoperative measure. Multivariable regression determined the prognostic utility of neutrophil gelatinase-associated lipocalin and creatinine, alone and in combination, for the primary composite outcome of hospital mortality or renal replacement therapy. The primary outcome occurred in 25 patients. Adjusted for covariates ΔSCr-initial greater than or equal to 0.0 mg/dL provided early prognostic utility for the primary outcome (odds ratio, 8.9; 95% CI, 3.0-26.6), the odds ratio comparable to a creatinine-based Kidney Disease: Improving Global Outcomes definition of acute kidney injury applied over 7 days postoperatively. The upper quartile of urinary neutrophil gelatinase-associated lipocalin best predicted the primary outcome when measured 18-24 hours post-cardiopulmonary bypass (odds ratio, 18.6; 95% CI, 5.1-68.4; p = 0.001) with earlier post-cardiopulmonary bypass measures of uncertain utility. Combining both ΔSCr-initial and neutrophil gelatinase-associated lipocalin measured 3 hours after cardiopulmonary bypass provided excellent early risk stratification for the primary outcome (odds ratio, 18.3; 95% CI, 4.5-75.0).

CONCLUSIONS

Combining urinary neutrophil gelatinase-associated lipocalin with a novel creatinine-based metric, both available soon after completion of surgery, may provide previously unavailable early and effective risk stratification for serious adverse outcomes after cardiac surgery.

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.

High serum and urine neutrophil gelatinase-associated lipocalin levels are independent predictors of renal progression in patients with immunoglobulin A nephropathy

BACKGROUND/AIMS

Tubulointerstitial injury plays an important role in the progression of immunoglobulin A nephropathy (IgAN), and neutrophil gelatinase-associated lipocalin (NGAL) is among the most sensitive tubular biomarkers. We investigated whether serum or urine NGAL predicts prognosis in patients with IgAN.

METHODS

The present study enrolled patients with biopsy-proven IgAN from January 2005 to December 2010, whose serum and urine samples at the time of kidney biopsy were preserved by freezing. We retrospectively reviewed patient clinical data and followed patients until October 2012. Serum and urine NGAL levels were measured using an enzyme-linked immunosorbent assay kit. Renal progression was defined as an estimated glomerular filtration rate decline by > 50% or progression to end-stage renal disease.

RESULTS

There were 121 patients enrolled in this study. During the median follow-up period of 41.49 months, renal progression was found in nine patients (7.4%). Serum or urine NGAL alone could not predict renal progression; however, when serum and urine NGAL levels were combined, belonging to the high NGAL group independently predicted renal progression (hazard ratio [HR], 5.56; 95% confidence interval [CI], 1.42 to 21.73; p = 0.014), along with tubular damage graded according to the Oxford classification as T2 (HR, 8.79; 95% CI, 2.01 to 38.51; p = 0.004). In addition, a Kaplan-Meier curve of renal survival showed significantly higher renal progression in patients in the high NGAL group (log rank, p = 0.004).

CONCLUSIONS

In patients with IgAN, high serum and urine NGAL levels at the time of kidney biopsy predict renal progression.