Neutrophil gelatinase-associated lipocalin--an emerging troponin for kidney injury

Prognostic Value of Serum Neutrophil Gelatinase-Associated Lipocalin in Acute Heart Failure: A Meta-Analysis

Background

Neutrophil gelatinase-associated lipocalin (NGAL) is not only a sensitive marker of acute kidney injury but may also be a prognostic marker of acute heart failure (AHF). This study aimed to investigate the relationship between serum NGAL and all-cause death (ACD) and the composite outcome of ACD or AHF readmissions in patients with AHF.

Methods

The Embase, Cochrane Library, and PubMed databases were searched for articles focusing on serum NGAL and ACD and the composite outcome of ACD or AHF readmissions in patients with AHF. The hazard ratios (HRs) were pooled with random-effects models.

Results

The results from 2428 patients from seven studies were pooled in this article. Higher NGAL was relevant to an increased risk of ACD (HR, 1.89; 95% CI, 1.38 to 2.61) and the composite outcome of ACD or AHF readmissions (HR, 2.92; 95% CI, 1.62 to 5.27) in patients with AHF.

Conclusions

Serum NGAL has prognostic value for ACD and the composite outcome of ACD or AHF readmissions in AHF.

The PROSPERO registration

CRD42022322057, https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022322057.

An early and stable mouse model of polymyxin-induced acute kidney injury

BACKGROUND

Polymyxins have been revived as a last-line therapeutic option for multi-drug resistant bacteria and continue to account for a significant proportion of global antibiotic usage. However, kidney injury is often a treatment limiting event with kidney failure rates ranging from 5 to 13%. The mechanisms underlying polymyxin-induced nephrotoxicity are currently unclear. Researches of polymyxin-associated acute kidney injury (AKI) models need to be more standardized, which is crucial for obtaining consistent and robust mechanistic results.

METHODS

In this study, male C57BL/6 mice received different doses of polymyxin B (PB) and polymyxin E (PE, also known as colistin) by different routes once daily (QD), twice daily (BID), and thrice daily (TID) for 3 days. We continuously monitored the glomerular filtration rate (GFR) and the AKI biomarkers, including serum creatinine (Scr), blood urea nitrogen (BUN), neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule-1 (KIM-1). We also performed histopathological examinations to assess the extent of kidney injury.

RESULTS

Mice receiving PB (35 mg/kg/day subcutaneously) once daily exhibited a significant decrease in GFR and a notable increase in KIM-1 two hours after the first dose. Changes in GFR and KIM-1 at 24, 48 and 72 h were consistent and demonstrated the occurrence of kidney injury. Histopathological assessments showed a positive correlation between the severity of kidney injury and the changes in GFR and KIM-1 (Spearman's rho = 0.3167, P = 0.0264). The other groups of mice injected with PB and PE did not show significant changes in GFR and AKI biomarkers compared to the control group.

CONCLUSION

The group receiving PB (35 mg/kg/day subcutaneously) once daily consistently developed AKI at 2 h after the first dose. Establishing an early and stable AKI model facilitates researches into the mechanisms of early-stage kidney injury. In addition, our results indicated that PE had less toxicity than PB and mice receiving the same dose of PB in the QD group exhibited more severe kidney injury than the BID and TID groups.

Neutrophil Gelatinase-Associated Lipocalin for the Differentiation of Mucinous Pancreatic Cystic Lesions

Undetermined pancreatic cystic lesion (PCL) differentiation benefits from endoscopic ultrasound (EUS) based on morphology and cyst fluid analysis, but room for new biomarkers exists. Our aim was to assess the intracystic and serum diagnostic value of neutrophil gelatinase-associated lipocalin (Ngal) and interleukin 1 beta (IL-1β) for differentiation of PCLs. This prospective study included patients from one tertiary hospital, evaluated between April 2018 and May 2020. EUS fine-needle aspiration or pancreatic pseudocysts drainage was the source of PCL intracystic liquid. The final diagnosis was based on surgery or EUS results (morphology, cytology, glucose, and CEA-carcinoembryogenic antigen). The intracystic samples were tested for Ngal, IL-1β, glucose, and CEA, and serum for Ngal and IL-1β. We evaluated 63 cysts, 33 pseudocysts, and 30 non-inflammatory cysts. The diagnostic sensitivity and specificity for mucinous PCL was 70.8% and 92.3% for intracystic Ngal (cut-off: 500-800 ng/dL), without correlation with serum Ngal, no matter the inclusion of infected pseudocysts. After exclusion of infected pseudocysts, the sensitivity and specificity for glucose were 87% and 75%, respectively, and for CEA, they were 87.1%, and 96.8%, respectively. Intracystic Ngal shows promise in differentiating mucinous PCLs, but researchers need to conduct further studies to confirm its effectiveness. Intracystic IL-1β and serum Ngal made no diagnostic contribution.

Urinary biomarkers associated with acute kidney injury in pediatric mechanical circulatory support patients

BACKGROUND

In patients requiring mechanical circulatory support (MCS), the incidence of acute kidney injury (AKI) is between 37 and 63%. In this study, we performed an exploratory analysis evaluating the relationship of multiple urine biomarkers with AKI development in pediatric MCS patients.

METHODS

This is a single center retrospective study in a pediatric cohort receiving MCS from August 2014 to November 2020. We measured 14 urine biomarkers of kidney injury on day 1 following MCS initiation and analyzed their association with development of AKI in the first 7 days of MCS initiation.

RESULTS

Sixty patients met inclusion criteria. Patients with AKI were more likely to be supported by venoarterial extracorporeal membrane oxygenation (65% vs. 8.3%, p < 0.001), compared to the no AKI group and less likely to have ventricular assist devices (10% vs. 50%, p < 0.001). There was a significant increase in the median urine albumin and urine osteoactivin in the AKI group, compared to the no AKI group (p = 0.020 and p = 0.018, respectively). When normalized to urine creatinine (UCr), an increased log osteoactivin/UCr was associated with higher odds of AKI development (OR: 2.05; 95% CI: 1.07, 4.44; p = 0.028), and higher log epidermal growth factor (EGF)/UCr (OR: 0.41; 95% CI: 0.15, 0.96) was associated with decreased odds of AKI.

CONCLUSIONS

Early increase in urine osteoactivin is associated with AKI development within 7 days of MCS initiation in pediatric patients. Contrary, an increased urine EGF is associated with kidney protection. A higher resolution version of the Graphical abstract is available as Supplementary information.

The Value of Urinary NGAL, KIM-1, and IL-18 Measurements in the Early Detection of Kidney Injury in Oncologic Patients Treated with Cisplatin-Based Chemotherapy

Cisplatin is still a widely used anticancer drug characterized by significant nephrotoxicity. Acute kidney injury (AKI), diagnosed based on the Kidney Disease: Improving Global Outcomes (KDIGO) criteria, has limitations, including a delayed increase in creatinine. We determined the usefulness of neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and interleukin-18 (IL-18) in diagnosing AKI according to the KDIGO criteria in patients treated with cisplatin. We recruited 21 subjects starting cisplatin-based chemotherapy (Cisplatin-based group) and 11 treated with carboplatin-based chemotherapy or 5-fluorouracil regimens (non-cisplatin-based group). Blood and urine samples were collected during four subsequent cycles of chemotherapy (68 and 38 cycles, respectively). AKI occurred in four patients in the cisplatin-based group (5.9% of 68 cisplatin-based chemotherapy cycles). Among them, three urinary markers were increased by over 100% in two cases, two in one case and one in another. A doubling of at least one investigated parameter was observed more frequently during cisplatin-based chemotherapy (80.3% vs. 52.8%; OR = 3.65, 95% CI: 1.49-8.90; p < 0.01). The doubling of at least one new urinary AKI marker was more common in patients receiving cisplatin and frequently was not associated with overt AKI. Thus, a subclinical kidney injury detected by these markers occurs more frequently than deterioration in kidney function stated with creatinine changes.

Current Status of Protein Biomarkers in Urolithiasis-A Review of the Recent Literature

Urolithiasis is an increasingly common clinical problem worldwide. The formation of stones is a combination of metabolic status, environmental factors, family history and many other aspects. It is important to find new ways to quickly detect and assess urolithiasis because it causes sudden, severe pain and often comes back. One way to do this is by exploring new biomarkers. Current advances in proteomic studies provide a great opportunity for breakthroughs in this field. This study focuses on protein biomarkers and their connection to kidney damage and inflammation during urolithiasis.

The Review of Current Knowledge on Neutrophil Gelatinase-Associated Lipocalin (NGAL)

Neutrophil gelatinase-associated lipocalin (NGAL) is a 25-kDa protein that is secreted mostly by immune cells such as neutrophils, macrophages, and dendritic cells. Its production is stimulated in response to inflammation. The concentrations of NGAL can be measured in plasma, urine, and biological fluids such as peritoneal effluent. NGAL is known mainly as a biomarker of acute kidney injury and is released after tubular damage and during renal regeneration processes. NGAL is also elevated in chronic kidney disease and dialysis patients. It may play a role as a predictor of the progression of renal function decreases with complications and mortality due to kidney failure. NGAL is also useful in the diagnostic processes of cardiovascular diseases. It is highly expressed in injured heart tissue and atherosclerostic plaque; its serum concentrations correlate with the severity of heart failure and coronary artery disease. NGAL increases inflammatory states and its levels rise in arterial hypertension, obesity, diabetes, and metabolic complications such as insulin resistance, and is also involved in carcinogenesis. In this review, we present the current knowledge on NGAL and its involvement in different pathologies, especially its role in renal and cardiovascular diseases.

Biomarkers as Prognostic Predictors and Therapeutic Guide in Critically Ill Patients: Clinical Evidence

A biomarker is a molecule that can be measured in a biological sample in an objective, systematic, and precise way, whose levels indicate whether a process is normal or pathological. Knowing the most important biomarkers and their characteristics is the key to precision medicine in intensive and perioperative care. Biomarkers can be used to diagnose, in assessment of disease severity, to stratify risk, to predict and guide clinical decisions, and to guide treatments and response to them. In this review, we will analyze what characteristics a biomarker should have and how to ensure its usefulness, and we will review the biomarkers that in our opinion can make their knowledge more useful to the reader in their clinical practice, with a future perspective. These biomarkers, in our opinion, are lactate, C-Reactive Protein, Troponins T and I, Brain Natriuretic Peptides, Procalcitonin, MR-ProAdrenomedullin and BioAdrenomedullin, Neutrophil/lymphocyte ratio and lymphopenia, Proenkephalin, NefroCheck, Neutrophil gelatinase-associated lipocalin (NGAL), Interleukin 6, Urokinase-type soluble plasminogen activator receptor (suPAR), Presepsin, Pancreatic Stone Protein (PSP), and Dipeptidyl peptidase 3 (DPP3). Finally, we propose an approach to the perioperative evaluation of high-risk patients and critically ill patients in the Intensive Care Unit (ICU) based on biomarkers.

New Insights into Molecular Mechanisms of Chronic Kidney Disease

Chronic kidney disease (CKD) is a major public health problem with a developing incidence and prevalence. As a consequence of the growing number of patients diagnosed with renal dysfunction leading to the development of CKD, it is particularly important to explain the mechanisms of its underlying causes. In our paper, we discuss the molecular mechanisms of the development and progression of CKD, focusing on oxidative stress, the role of the immune system, neutrophil gelatinase-associated lipocalin, and matrix metalloproteinases. Moreover, growing evidence shows the importance of the role of the gut-kidney axis in the maintenance of normal homeostasis and of the dysregulation of this axis in CKD. Further, we discuss the therapeutic potential and highlight the future research directions for the therapeutic targeting of CKD. However, additional investigation is crucial to improve our knowledge of CKD progression and, more importantly, accelerate basic research to improve our understanding of the mechanism of pathophysiology.

Predictive and Prognostic Value of Serum Neutrophil Gelatinase-Associated Lipocalin for Contrast-Induced Acute Kidney Injury and Long-Term Clinical Outcomes after Percutaneous Coronary Intervention

Neutrophil gelatinase-associated lipocalin (NGAL) has been proposed as an early marker for estimating the risk of contrast-induced acute kidney injury (CI-AKI). However, the predictive value of baseline serum NGAL levels for CI-AKI remains unclear. Serum NGAL was measured before percutaneous coronary intervention in 633 patients with coronary artery disease. The primary clinical endpoints were a composite of major adverse cardiac and cerebrovascular events (MACCEs; cardiac death, myocardial infarction, stroke, and any revascularization). The mean follow-up duration was 29.4 months. Ninety-eight (15.5%) patients developed CI-AKI. Compared with patients without CI-AKI, baseline serum NGAL was higher in patients with CI-AKI (149.6 ± 88.8 ng/mL vs. 138.0 ± 98.6 ng/mL, p = 0.0279), although serum creatinine and estimated glomerular filtration rate were not different between groups. Patients in the highest tertile of baseline serum NGAL showed a significantly higher rate of MACCEs (10.5% vs. 3.8%, p = 0.02). Using the first tertile as a reference, the adjusted hazard ratios for MACCEs in patients in the second and third tertiles of NGAL were 2.151 (confidence interval (CI) 0.82 to 5.59, p = 0.116) and 2.725 (CI 1.05 to 7.05, p = 0.039), respectively. Baseline serum NGAL is a reliable marker for predicting CI-AKI, and high serum NGAL levels are associated with a higher incidence rate of long term MACCEs.

Evaluation of urinary neutrophil gelatinase-associated lipocalin to detect renal tubular damage in dogs with stable myxomatous mitral valve disease

BACKGROUND

Dogs with myxomatous mitral valve disease (MMVD) can experience progressive renal tubular damage and dysfunction. The prevalence of renal tubular damage is not known in dogs with stable MMVD.

OBJECTIVE

To evaluate renal tubular damage in dogs with stable MMVD by evaluation of urinary neutrophil gelatinase-associated lipocalin (NGAL).

ANIMALS

Ninety-eight MMVD dogs grouped according to the American College of Veterinary Internal Medicine (ACVIM) staging (group B1, n = 23; group B2, n = 27; group C + D, n = 48) and 46 healthy dogs.

METHODS

Multicenter prospective observational study. Serum and urine chemistry including NGAL reported as uNGAL concentration (uNGAL) and normalized with urinary creatinine (uNGALC) were compared between MMVD dogs and healthy controls, and among different MMVD ACVIM stages.

RESULTS

The MMVD dogs had significantly higher uNGAL and uNGALC (1204 pg/mL; range, 30-39 732 and 1816 pg/mg; range, 22-127 693, respectively) compared to healthy dogs (584 pg/mL; range, 56-4072 and 231 pg/mg; range, 15-2407, respectively; P = .002 and P < .0001, respectively). Both uNGAL and uNGALC increased with the increasing ACVIM stage (P = .001 and P < .001, respectively).

CONCLUSIONS AND CLINICAL IMPORTANCE

Renal tubular damage is present in dogs with stable MMVD, as measured by increased uNGAL. This tubular damage is subclinical, occurs in all stages of MMVD even in the absence of azotemia, and increases with the severity of MMVD. Reno-protective approaches to manage MMVD dogs should be explored to slow the progression of renal tubular damage in these patients.

Spatiotemporal organisation of protein processing in the kidney

The kidney regulates plasma protein levels by eliminating them from the circulation. Proteins filtered by glomeruli are endocytosed and degraded in the proximal tubule and defects in this process result in tubular proteinuria, an important clinical biomarker. However, the spatiotemporal organization of renal protein metabolism in vivo was previously unclear. Here, using functional probes and intravital microscopy, we track the fate of filtered proteins in real time in living mice, and map specialized processing to tubular structures with singular value decomposition analysis and three-dimensional electron microscopy. We reveal that degradation of proteins requires sequential, coordinated activity of distinct tubular sub-segments, each adapted to specific tasks. Moreover, we leverage this approach to pinpoint the nature of endo-lysosomal disorders in disease models, and show that compensatory uptake in later regions of the proximal tubule limits urinary protein loss. This means that measurement of proteinuria likely underestimates severity of endocytotic defects in patients.

Polesel et al. visualize plasma protein filtration, uptake and metabolism in the kidneys of living mice in real-time. They reveal coordinated activity of different specialized tubular segments, with major compensatory adaptations occurring in disease states.

The Use of Neutrophil Gelatinase-Associated Lipocalin (NGAL) as a Diagnostic and Prognostic Biomarker in Urinary Tract Obstruction: a Systematic Review

PURPOSE OF REVIEW

The early recognition of urinary tract obstruction (UTO) is vital in order to prevent mortality and morbidity associated with an acute kidney injury (AKI) and progression to irreversible kidney damage. Urinary biomarkers such as neutrophil gelatinase-associated lipocalin (NGAL) have been recognised as an accurate tool in the timely diagnosis of AKI, but its role in the detection, prognosis and subsequent monitoring of a variety of obstructive uropathies has not yet been explored. We performed a systematic review of literature in accordance with Cochrane methodology from inception to August 2021.

RECENT FINDINGS

Eleven studies were included in which urine and serum NGAL were measured (616 patients) presenting with multiple UTO aetiologies. Four investigated kidney stone disease (KSD) exclusively, whilst other studies identified other causes of UTO including pelviureteric junction obstruction (PUJO), retroperitoneal fibrosis (RPF) and ureteric strictures. Six studies monitored NGAL levels after surgical intervention to relieve the obstruction. Nine studies demonstrated a significant increase in both urine and serum NGAL levels in UTO, often in a more sensitive and timely manner than serum creatinine. Subclinical unilateral UTO could be recognised by urinary NGAL levels even in the absence of changes in serum creatinine. Following surgical intervention, a reduction in urinary and serum NGAL was seen in all but two studies. NGAL levels decreased acutely by 14% in 2 h and showed a long-term reduction of 78% in 6 months. Readily available but not yet widely accepted, NGAL has the potential to be a less invasive, low-cost diagnostic test for urinary tract obstructions as a whole. Not only can it be used as a marker of treatment success but also to monitor for obstruction recurrence or progression. Further research is required to acknowledge urinary biomarkers such as NGAL as a potential replacement to standard renal function monitoring tests in the context of obstructive uropathy.

Evaluation of postoperative renal functions and its effect on body perfusion in patients with double aortic cannulation

BACKGROUND

The optimal visceral preservation method during aortic arch reconstruction is still controversial. It has been thought that double aortic cannulation is effective. Herein, it was aimed to evaluate this technique in providing distal perfusion.

METHODS

A total of 74 patients who underwent arch reconstruction between 2011 and 2019 were included. Patients were grouped according to ventricular physiology and cannulation strategies. Group 1 were univentricle patients, and all had double aortic cannulation. Group 2 were biventricular patients. Group 2A double aortic cannulation-done and Group 2B non-double aortic cannulation were included. Lactate, urea, creatinine values, renal functions, and need for peritoneal dialysis of patients were evaluated.

RESULTS

There were no complications observed due to descending aortic cannulation in any of the patients. A delayed sternal closure and the need for peritoneal dialysis were more common in the Group 1 (p < 0.01). The preoperative and postoperative 1st- and 2nd-day lactate, urea, and creatinine values in the Group 1 were higher (p < 0.05) when compared with the Group 2A and 2B. The same values were higher in Group 2A than the Group 2B (p < 0.05).

CONCLUSION

The positive effect of double aortic cannulation on renal dysfunction could not be demonstrated. This may be associated with a <1 month of age, low weight, complex surgical procedure, and high preoperative lactate, urea, and creatinine values in patients with double aortic cannulation.

Renal effect of severe hypoxia evaluated By NGAL measurements: An in vivo and in vitro study

PURPOSE

To investigate possible renal damage in healthy men exposed to extreme hypobaric hypoxia, using urinary Neutrophil Gelatinase-Associated Lipocalin (NGAL) concentration as biomarker. The value of NGAL as a biomarker of proximal tubular cell damage under hypoxic conditions was also tested in vitro experiments.

METHODS

NGAL was assayed in a cohort of air cadets (n = 16) exposed to hypobaric hypoxia in a hypobaric chamber during their training program. In all subjects, urine creatinine (Cr) and urinary NGAL levels were measured immediately before, 3, and 24 h after hypobaric environment exposure. Three in vitro experiments using proximal tubular cell cultures were also performed to measure NGAL gene expression, NGAL secretion in the culture medium and to evaluate apoptosis under two cycles of hypoxia and reoxygenation.

RESULTS

In the in vivo study, geometric means of urinary NGAL/Cr ratio measured 24 h after hypobaric hypoxia in the hypobaric chamber were significantly lower than baseline values (13.4 vs 25.9 ng/mg, p = 0.01). In cell cultures, hypoxia down-regulated NGAL gene expression without significantly changing NGAL secretion in the culture medium. Hypoxia significantly increased the percentage of apoptotic/necrotic cells, especially after the second hypoxia-reoxygenation cycle.

CONCLUSIONS

Exposure to hypobaric-hypoxic environments does not cause significant and irreversible renal tubular injury in vivo and in vitro, except than in a late stage. The hypoxic insult does not seem to be mirrored by an increase of urinary NGAL in healthy men nor of NGAL gene expression in HK-2 cell culture or secretion in the culture medium in the in vitro conditions reported in the present study.

Effect of Geumgwe-Sinkihwan on Renal Dysfunction in Ischemia/Reperfusion-Induced Acute Renal Failure Mice

Renal ischemia-reperfusion (I/R) injury is an important cause of acute renal failure (ARF). Geumgwe-sinkihwan (GSH) was recorded in a traditional Chines medical book named “Bangyakhappyeon” in 1884. GSH has been used for treatment for patients with diabetes and glomerulonephritis caused by deficiency of kidney yang and insufficiency of kidney gi. Here we investigate the effects of GSH in mice model of ischemic acute kidney injury. The mice groups are as follows; sham group: C57BL6 male mice, I/R group: C57BL6 male mice with I/R surgery, GSH low group: I/R + 100 mg/kg/day GSH, and GSH high group: I/R + 300 mg/kg/day GSH. Ischemia was induced by clamping both renal arteries and reperfusion. Mice were orally given GSH (100 and 300 mg/kg/day) during 3 days after surgery. Treatment with GSH significantly ameliorated creatinine clearance, creatinine, and blood urea nitrogen levels. Treatment with GSH reduced neutrophil gelatinase associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1), specific renal injury markers. GSH also reduced the periodic acid–Schiff and picro sirius red staining intensity in kidney of I/R group. Western blot and real-time RT-qPCR analysis demonstrated that GSH decreased protein and mRNA expression levels of the inflammatory cytokines in I/R-induced ARF mice. Moreover, GSH inhibited protein and mRNA expression of inflammasome-related protein including NLRP3 (NOD-like receptor pyrin domain-containing protein 3, cryoprin), ASC (Apoptosis-associated speck-like protein containing a CARD), and caspase-1. These findings provided evidence that GSH ameliorates renal injury including metabolic dysfunction and inflammation via the inhibition of NLRP3-dependent inflammasome in I/R-induced ARF mice.

Plasma Neutrophil Gelatinase-Associated Lipocalin Is Useful for Predicting Mortality in Critically Ill Patients

Elevated neutrophil gelatinase-associated lipocalin (NGAL) occurs in a wide range of systemic diseases. This study examined the clinical utility of plasma NGAL to predict intensive care unit (ICU) and in-hospital mortality in critically ill patients. A total of 62 patients hospitalized in a mixed ICU were included; pNGAL, creatinine, and C-reactive protein (CRP) were assayed on four consecutive days (D1-D4) following ICU admission. APACHE II score (Acute Physiology and Chronic Health Evaluation) was calculated 24 h post-admission. ICU mortality reached 35% and in-hospital mortality was 39%. The median pNGAL at admission was 142.5 (65.6-298.3) ng/mL. pNGAL was significantly higher in non-survivors compared to survivors. The highest accuracy for ICU mortality prediction was achieved at the pNGAL cutoff of 93.91 ng/mL on D4 area under the curve (AUC) = 0.89; 95%CI 0.69-0.98 and for in-hospital mortality prediction was achieved at the pNGAL cutoff of 176.64 ng/mL on D3 (AUC = 0.86; 95%CI 0.69-0.96). The APACHE II score on ICU admission predicted ICU mortality with AUC = 0.89 (95%CI 0.79-0.96) and in-hospital mortality with AUC = 0.86 (95%CI 0.75-0.94). Although pNGAL on D1 poorly correlated with APACHE II (R = 0.3; p = 0.01), the combination of APACHE II and pNGAL on D1 predicted ICU mortality with AUC = 0.90 (95%CI 0.79-0.96) and in-hospital mortality with AUC = 0.95 (95%CI 0.78-0.99). Maximal CRP during study observation failed to predict ICU mortality (AUC = 0.62; 95%CI 0.49-0.74), but helped to predict in-hospital mortality (AUC = 0.67; 95%CI 0.54-0.79). Plasma NGAL with combination with the indices of critical illness is a useful biomarker for predicting mortality in heterogeneous population of ICU patients.

Role of urinary biomarkers for diagnosis and prognosis of kidney stone disease

PURPOSE OF REVIEW

Urinary biomarkers such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1) and N-acetyl-B-D-glucosamindase (NAG) are recognised as being useful for the detection of kidney tubular damage but their role in the diagnosis and prognosis of kidney stone disease (KSD) is still unknown. To clarify this, we performed a systematic review of literature in accordance with Cochrane methodology from inception to September 2020.

RECENT FINDINGS

Twelve studies were included and a variety of urinary biomarkers (KIM-1, NGAL, NAG, proteins/peptides, cytokines, CA19-9) were measured in a total of 998 patients with KSD. Despite some contradicting studies, majority of the biomarkers studied showed a significant rise in patients with KSD compared to healthy controls, with levels decreasing after their surgical management, noticed as early as 4 h postprocedure. There was limited evidence of correlation with stone burden and elevated levels were also associated with hydronephrosis and superimposed infections.

SUMMARY

Urinary biomarkers could be used in the diagnosis, prognosis and stone-treatment response in patients with KSD. However, as novel indicators, they may not be reliable as the sole diagnostic or prognostic tool for KSD as they are readily confounded by other causes of kidney injury. Further studies are needed to determine their ability to separate KSD from other causes of obstructive uropathy and acute renal injury.

Current concepts and advances in biomarkers of acute kidney injury

Despite advancements in standardizing the criteria for acute kidney injury (AKI), its definition remains based on changes in serum creatinine and urinary output that do not specifically represent tubular function or injury and that have significant limitations in the acute hospital setting. Much effort in nephrology has centered on identifying biomarkers of AKI to address these limitations. This review summarizes recent advances in our knowledge of biomarkers involved in pathophysiological processes during AKI and describes their potential clinical implications. Blood and urine biomarkers are released via various mechanisms during renal tubular injury. Urinary kidney injury molecule-1 (KIM-1), liver-type fatty acid binding protein (L-FABP), insulin-like growth factor-binding protein-7 (IGFBP-7), and tissue inhibitor of metalloprotease-2 (TIMP-2) are released from the proximal tubule while uromodulin (UMOD) is secreted from the loop of Henle and neutrophil gelatinase-associated lipocalin (NGAL) is released from the distal tubule. These biomarkers could therefore be used to localize specific segments of injured tubules. Biomarkers also have diverse roles in pathophysiological processes in AKI, including inflammation, repair, and fibrosis. Current evidence suggests that these biomarkers could be used to predict the transition to chronic kidney disease (CKD), decrease discard of AKI kidneys, differentiate between kidney dysfunction and injury, guide AKI management, and improve diagnosis of diseases such as acute interstitial nephritis (AIN). They could differentiate between disease phenotypes, facilitate the inclusion of a homogenous patient population in future trials of AKI, and shed light on therapeutic pathways to prevent the transition from AKI to CKD. However, a major limitation of current biomarker research in AKI is the lack of tissue correlation. The Kidney Precision Medicine Project, a large-scale national effort, is currently underway to construct a kidney tissue atlas and expand the use of biomarkers to assess nephron health. Numerous biomarkers are involved in distinct pathophysiological processes after kidney injury and have demonstrated potential to improve diagnosis and risk stratification as well as provide a prognosis for patients with AKI. Some biomarkers are ready for use in clinical trials of AKI and could guide management in various clinical settings. Further investigation of these biomarkers will provide insight that can be applied to develop novel therapeutic agents for AKI.

Cilomilast Ameliorates Renal Tubulointerstitial Fibrosis by Inhibiting the TGF-β1-Smad2/3 Signaling Pathway

Background: Renal tubulointerstitial fibrosis is the key pathological feature in chronic kidney diseases (CKDs) with no satisfactory therapies in clinic. Cilomilast is a second-generation, selective phosphodiesterase-4 inhibitor, but its role in renal tubulointerstitial fibrosis in CKD remains unclear.

Material and Methods: Cilomilast was applied to the mice with unilateral ureteric obstruction (UUO) and renal fibroblast cells (NRK-49F) stimulated by TGF-β1. Renal tubulointerstitial fibrosis and inflammation after UUO or TGF-β1 stimulation were examined by histology, Western blotting, real-time PCR and immunohistochemistry. KIM-1 and NGAL were detected to evaluate tubular injury in UUO mice.

Results:In vivo, immunohistochemistry and western blot data demonstrated that cilomilast treatment inhibited extracellular matrix deposition, profibrotic gene expression, and the inflammatory response. Furthermore, cilomilast prevented tubular injury in UUO mice, as manifested by reduced expression of KIM-1 and NGAL in the kidney. In vitro, cilomilast attenuated the activation of fibroblast cells stimulated by TGF-β1, as shown by the reduced expression of fibronectin, α-SMA, collagen I, and collagen III. Cilomilast also inhibited the activation of TGF-β1-Smad2/3 signaling in TGF-β1-treated fibroblast cells.

Conclusion: The findings of this study suggest that cilomilast is protective against renal tubulointerstitial fibrosis in CKD, possibly through the inhibition of TGF-β1-Smad2/3 signaling, indicating the translational potential of this drug in treating CKD.

Plasma Lipocalin-2 and Adiponectin are Affected by Obesity Rather Than Type 2 Diabetes Mellitus per se

PURPOSE

Changes in plasma adipocytokines and inflammatory markers in type 2 DM remain controversial as to whether they are due to obesity or directly associated with the diabetic state. Our objective was to study the effect of obesity and diabetes on plasma lipocalin-2 (LCN2), adiponectin, and interleukin-1β (IL-1β) by comparing their levels in non-diabetic obese subjects and non-obese type 2 DM patients, as well as determining the association of these adipocytokines with metabolic syndrome factors and diabetic parameters.

PATIENTS AND METHODS

In this study, 85 Yemeni male volunteers aged 30-60 years old were enrolled, 25 of whom were healthy subjects with BMI < 25 kg/m² served as control; 30 non-diabetic obese subjects (BMI ≥ 30 kg/m² and FBG < 6.1 mmol/l); and 30 non-obese type 2 DM patients (BMI < 25 kg/m² and FBG > 7 mmol/l).

RESULTS

Lipocalin-2 and adiponectin were significantly (p = 0.043 and p = 0.034) lower in non-diabetic obese subjects by 16.2% and 29.7% with respect to control group, with no effect in the non-obese type 2 DM patients. Moreover, LCN2 was significantly (p = 0.04) lower in the non-diabetic obese subjects by 15.8% as compared with the non-obese type 2 DM patients, with no significant difference in adiponectin levels. In contrast, serum IL-1β was significantly (p = 0.001 and p = 0.003) higher in both non-diabetic obese subjects and the non-obese type 2 DM patients by 76.5% and 67.7% as compared to control group. The significant decrease in both LCN2 and adiponectin and the significant increase in IL-1β in the non-diabetic obese subjects disappeared upon adjustment for waist circumference (WC). In contrast, the significant increase in IL-1β in the non-obese Type 2 DM patients was not affected upon adjustment for WC.

CONCLUSION

Plasma LCN2 and adiponectin were not affected by diabetes per se, suggesting that the observed changes in LCN2 and adiponectin in type 2 DM may be due to obesity rather than the diabetic state, whereas IL-1β levels were affected by both obesity and diabetes.

Incorporation of Urinary Neutrophil Gelatinase-Associated Lipocalin and Computed Tomography Quantification to Predict Acute Kidney Injury and In-Hospital Death in COVID-19 Patients

Background

The prevalence of acute kidney injury (AKI) in COVID-19 patients is high, with poor prognosis. Early identification of COVID-19 patients who are at risk for AKI and may develop critical illness and death is of great importance.

Objective

The aim of this study was to develop and validate a prognostic model of AKI and in-hospital death in patients with COVID-19, incorporating the new tubular injury biomarker urinary neutrophil gelatinase-associated lipocalin (u-NGAL) and artificial intelligence (AI)-based chest computed tomography (CT) analysis.

Methods

A single-center cohort of patients with COVID-19 from Wuhan Leishenshan Hospital were included in this study. Demographic characteristics, laboratory findings, and AI-assisted chest CT imaging variables identified on hospital admission were screened using least absolute shrinkage and selection operator (LASSO) and logistic regression to develop a model for predicting the AKI risk. The accuracy of the AKI prediction model was measured using the concordance index (C-index), and the internal validity of the model was assessed by bootstrap resampling. A multivariate Cox regression model and Kaplan-Meier curves were analyzed for survival analysis in COVID-19 patients.

Results

One hundred seventy-four patients were included. The median (±SD) age of the patients was 63.59 ± 13.79 years, and 83 (47.7%) were men.u-NGAL, serum creatinine, serum uric acid, and CT ground-glass opacity (GGO) volume were independent predictors of AKI, and all were selected in the nomogram. The prediction model was validated by internal bootstrapping resampling, showing results similar to those obtained from the original samples (i.e., 0.958; 95% CI 0.9097–0.9864). The C-index for predicting AKI was 0.955 (95% CI 0.916–0.995). Multivariate Cox proportional hazards regression confirmed that a high u-NGAL level, an increased GGO volume, and lymphopenia are strong predictors of a poor prognosis and a high risk of in-hospital death.

Conclusions

This model provides a useful individualized risk estimate of AKI in patients with COVID-19. Measurement of u-NGAL and AI-based chest CT quantification are worthy of application and may help clinicians to identify patients with a poor prognosis in COVID-19 at an early stage.

Assessing the health of the nephron in acute kidney injury: biomarkers of kidney function and injury

PURPOSE OF REVIEW

Serum creatinine and urine output continue to be the mainstays of diagnosis of acute kidney injury, though both of these measures have significant limitations, especially in acutely hospitalized patients. Biomarkers in both blood and urine have been studied extensively in the research setting and are on the verge of clinical practice to improve diagnosis of AKI.

RECENT FINDINGS

Blood and urine biomarkers can be localized to specific areas or functions within the nephron. Biomarkers can help to characterize glomerular or tubular function; glomerular, tubular, or interstitial injury; inflammation; or repair. Further, biomarkers can improve diagnosis of AKI in various clinical settings including acute interstitial nephritis, acute tubular injury, and hepatorenal syndrome, and cardiorenal syndrome.

SUMMARY

Biomarkers are becoming more prevalent in both research and getting close to clinical use. Both blood and urine biomarkers can help to localize impairment in nephron health by either location or function within the nephron and among various causes of AKI.

Variation in clinical usefulness of biomarkers of acute kidney injury in young children undergoing cardiac surgery

BACKGROUND

Acute kidney injury (AKI) is one of the most significant postoperative complications of pediatric cardiac surgery. Because serum creatinine has limitations as a diagnostic marker of AKI, new biomarkers including neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and interleukin-18 (IL-18) are being evaluated to overcome these limitations and detect AKI at an early stage after cardiac surgery.

PURPOSE

This study aimed to investigate the clinical usefulness of these biomarkers in young children.

METHODS

Thirty patients with congenital heart diseases who underwent cardiac surgery using cardiopulmonary bypass (CPB) were selected, and their urine and blood samples were collected at baseline and 6, 24, and 48 hours after surgery. Serum creatinine and blood urea nitrogen levels as well as NGAL, KIM-1, and IL-18 levels in urine samples were measured, and clinical parameters were evaluated.

RESULTS

Of the 30 patients, 12 developed AKI within 48 hours after cardiac surgery. In the AKI group, 8 of 12 (66.6%) met AKI criteria after 24 hours, and urine KIM-1/creatinine (Cr) level (with adjustment of urine creatinine) peaked at 24 hours with significant difference from baseline level. Additionally, urine KIM-1/Cr level in the AKI group was significantly higher than in the non-AKI group at 6 hours. However, urine NGAL/Cr and IL-18/Cr levels showed no specific trend with time for 48 hours after cardiac surgery.

CONCLUSION

It is suggested that urine KIM-1/Cr concentration could be considered a good biomarker for early AKI prediction after open cardiac surgery using CPB in young children with congenital heart diseases.

Neutrophil Gelatinase-Associated Lipocalin as an Early Diagnostic Biomarker of Acute Kidney Injury in Snake Bite

Background:

Snakebite envenomation is a major public health problem in the developing world, and the effects of viper envenomation on renal tissues leading to acute kidney injury (AKI) are well known. However, the usefulness of neutrophil gelatinase-associated lipocalin (NGAL) as a biomarker to detect AKI in viper envenomation cases were not studied much.

Aims and Objectives:

The present study was undertaken to find out plasma NGAL levels and assess its usefulness among the hospitalized Viperidae group of snakebite victims in predicting acute kidney injury.

Materials and Methods:

The plasma NGAL level was estimated within 6–8 h of all the 184 cases of viper bites along with other laboratory parameters.

Results:

It was elevated much before the elevation of serum creatinine levels, irrespective of the age, gender, and bite to hospital time. The sensitivity and specificity was 99.37 and 96.15, respectively. Elevated plasma NGAL levels in viper bite helped not only to detect AKI early but also assisted to plan for appropriate intervention.

Conclusion:

It is suggested to include estimation of plasma NGAL in the point of care testing, especially in emergency settings handling snakebite cases. However, more studies are recommended to find out its serial levels in snakebite cases following different kinds of snake envenomation with different clinical and laboratory manifestations in different age groups and gender belonging to different population so as to arrive at valid conclusions.

The role of neutrophils in the pathogenesis of atherosclerosis

Atherosclerosis (AS) is one of the causes of cardiovascular disease. The formation of atherosclerotic lesions of the arteries is a long process, and clinical symptoms appear already at the stage of atherosclerotic plaque (ASB), which prevents blood flow and can cause coronary heart disease, as well as acute coronary syndrome. The study of atherosclerosis mechanisms at the subclinical level is relevant. This article provides a summary of current data on the structure and functions of neutrophils (NF) in physiological processes. Particular attention is paid to the participation of neutrophils in the damage and formation of vascular endothelial dysfunction. Discusses several mechanisms of involvement of neutrophils in atherogenesis: the production of reactive oxygen species, which cause direct endothelial damage; the synthesis of cytokines that trigger the migration of leukocytes in inflammation; the formation of protein complexes with cholesterol, contributing to their deposition in the vessels, and neutrophil traps, triggering destructive-alterative reactions.

Comparison of urine neutrophil gelatinase-associated lipocalin and interleukin-18 in prediction of acute kidney injury in adults

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) and interleukin-18 (IL-18) were considered as the most promising biomarkers in prediction of acute kidney injury (AKI), but the priority of them remains unclear.

METHODS

Databases of PubMed, Elsevier, Cochrane library, and Web of science were searched until August 23, 2017 for studies investigated the diagnostic value of urine NGAL (uNGAL) and urine IL-18 (uIL-18) for AKI in adults. Statistical analysis and investigation of heterogeneity source were using RevMan5.3, MetaDiSc1.40, and Stata14.0.

RESULTS

A total of 7 studies were included involving 2315 patients from 7 countries in this article, of whom 443 (19.1%) developed AKI. The present meta-analysis demonstrated that uNGAL was more valuable compare with uIL-18 with effect size of 1.09 (95% CI 1.03-1.15, P = .004) in specificity, but not in sensitivity with effect size of 1.12 (95% CI 0.98-1.29, P = .104). Subgroup analysis presented that research design may be a foundation affecting the diagnostic accuracy of uNGAL and uIL-18 for AKI. No substantial publication bias was found.

CONCLUSIONS

uNGAL is more specific for prediction of AKI in adults as compared with uIL-18.

Urine neutrophil gelatinase-associated lipocalin predicts outcome and renal failure in open and endovascular thoracic abdominal aortic aneurysm surgery

Urine neutrophil gelatinase–associated lipocalin (uNGAL) has been evaluated as a biomarker for AKI detection and adverse outcome in open and endovascular thoracoabdominal aortic aneurysm surgery. This observational, retrospective study included 52 patients. UNGAL was measured peri-operatively (48 h) and correlated with AKI requiring dialysis, tracheotomy and adverse outcome. Mean patients’ age was 64.5 years. A total of 26.9% (n = 14) developed AKI, and 21.1% (n = 11) required dialysis, tracheotomy rate was 19.2% (n = 10) and in-hospital mortality rate was 7.6% (n = 4). uNGAL levels were related to AKI requiring dialysis at ICU (p = 0.0002), need for tracheotomy at baseline and admission on ICU (p = 0.0222, p = 0.0028, respectively), as well as adverse discharge modality (p = 0.0051, p = 0.0048, respectively). Diagnostic quality was good for uNGAL levels at admission to ICU regarding AKI requiring dialysis (sensitivity: 81.8% [48.2–97.7]; specificity: 87.8% [73.8–95.9]; area under the curve (AUC): 0.874 [0.752–0.949]). The diagnostic quality of uNGAL was favorable for the prediction of tracheotomy (sensitivity: 70.0% [34.8–93.3]; specificity: 83.3% [68.6–93.0]; AUC: 0.807 [0.674–0.903]) and adverse discharge (sensitivity: 77.8% [40.0–97.2]; specificity: 83.7% [69.3–93.2]; AUC: 0.817 [0.685–0.910]). uNGAL may be valuable as an post-operative predictor of AKI and adverse outcome after open and endovascular TAAA repair.

N-acetylcysteine decreases urinary level of neutrophil gelatinase-associated lipocalin in deceased-donor renal transplant recipients: a randomized clinical trial

CONTEXT

Acute kidney injury (AKI) is a common complication after kidney transplantation (KT), especially in recipients from deceased donors. Urinary neutrophil gelatinase-associated lipocalin (u-NGAL) is an early and sensitive marker of AKI after transplantation.

OBJECTIVES

We assessed the renoprotective effect of N-acetylcysteine (NAC) on u-NGAL levels as an early prognostic marker of graft function immediately after transplantation.

MATERIALS AND METHODS

A double-blind, randomized, placebo-controlled trial was conducted on 70 deceased-donor KT recipients ( www.irct.ir , trial registration number: IRCT2014090214693N4). Patients received 600 mg oral NAC or placebo twice daily from day 0 to 5 and urine samples were taken before, and on the first and fifth days after transplantation. U-NGAL and early graft function were compared between the two groups.

RESULTS

NAC significantly reduced u-NGAL levels compared to placebo (p value = 0.02), while improvement in early graft function with NAC did not reach statistical significance.

CONCLUSIONS

This study showed that NAC administration in deceased-donor KT recipients can reduce tubular kidney injury, evidenced by u-NGAL measurements. Improvement in early graft function needs a larger sample size to reach a statistical conclusion.

Salivary Neutrophil Gelatinase-Associated Lipocalin Sampling Feasibility in Acute Renal Colic

PURPOSE

Neutrophil gelatinase-associated lipocalin (NGAL) levels in the serum and urine are predictive biomarkers of acute kidney injury with correlation to complication and survival in major surgery. Salivary levels of NGAL during acute renal colic may reflect the degree of renal injury as it appears in different compartments encompassing body response in time perspective. Our aim is to evaluate and examine the feasibility and correlation of salivary NGAL with serum and urine levels in acute renal colic event.

MATERIALS AND METHODS

A prospective controlled study of all patients presenting to the emergency room with acute renal colic event diagnosed with single ureteral stone obstruction by noncontrast CT. Saliva, urine, and blood samples were collected in patients and a control group during the first morning of admission.

RESULTS

The study groups consisted of 44 patients and 13 controls, mean age 47 ± 15 years, body mass index 29 ± 6, mean stone size 6 ± 4 mm, mean creatinine levels 1.3 ± 0.7 mg/dL, mean white blood count 10,900 ± 3100 counts per field, and C-reactive protein 29 ± 55. Serum (190 ± 120 ng/mL vs 81 ± 24; p < 0.001) and predominantly salivary (474 ± 185 vs 328 ± 134 ng/mL; p < 0.05) NGAL levels were significantly elevated in patients compared with controls.

CONCLUSIONS

Salivary NGAL sampling is feasible during the acute phase of renal colic. High levels of salivary NGAL are observed in a single sampling during acute ureteral stone obstruction and may advance clinical decision-making.

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

Objectives:

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

Methods:

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

Results:

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

Conclusions:

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

Ischemic modified albumin increases in acute kidney injury

Purpose: Acute kidney injury (AKI) is a severe kidney disease carrying high morbidity and mortality. An ischemic process, at the cellular level, has been detected prior to the full-blown AKI. An elevated ischemic modified albumin (IMA) was also found to be increased fast at several minutes following an ischemic process in the body. In this connection, we have investigated, in advance, the changes of IMA concentrations in patients with possible AKI. Methods: IMA and other biochemical and haematological parameters were measured in sera of thirty nine patients with AKI and of thirty eight healthy controls. AKI is defined by an increase in serum creatinine by ≥ 0.3 mg/dl in 48 hours or an increase by ≥ 1.5-fold from a known or assumed baseline. The results in the two groups were compared. Results: IMA, creatinine, blood urea nitrogen, white blood cell, neutrophil, neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR) and mean platelet volume were found to be higher in patients with AKI than in healthy controls. In contrast, total protein, albumin, lymphocyte, and haemoglobin were lower in patients with AKI than in healthy controls. No significant difference was recorded in platelet counts between the two groups. Conclusion: Our results indicate that increased levels of NLR and PLR play a central role in a systemic inflammation in AKI. Monitoring serum IMA could be a useful tool in the assessment of AKI.

Myo-inositol Oxygenase as a Novel Marker in the Diagnosis of Acute Kidney Injury

Background

Due to the lack of diagnostic efficiency of serum creatinine in acute kidney injury (AKI), there is a pressing need to develop novel diagnostic markers. Therefore, in this study, we evaluated myo–inositol oxygenase (MIOX), neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C in terms of their applicability in the diagnosis of AKI.

Methods

We enrolled a total of 39 AKI patients and 38 healthy controls in the study. We compared the levels of serum MIOX, NGAL and cystatin C between the two groups.

Results

We found that the concentrations of serum creatinine, blood-urea nitrogen, MIOX and cystatin C were higher in the AKI group. According to the receiver operating characteristic analysis, the area under the curve (AUC) values were 0.694 (95% CI 0.579-0.794) for MIOX and 0.976 (95% CI; 0.912-0.997) for cystatin C. For MIOX, when the cut-off concentration was set to 77.3 pg/mL, the diagnostic sensitivity and specificity were found to be 53.8% (95% CI; 37.2-69.9) and 81.5 (95% CI; 65.7-92.3), respectively. For cystatin C, at the cut-off value of 14 mg/L, the diagnostic sensitivity and specificity were 94.8% (95% CI; 82.7-99.4) and 94.7 % (95% CI 82.3-99.4), respectively.

Conclusion

The measurement of serum MIOX and cystatin C levels is valuable for the diagnosis of AKI. Further research is needed for the evaluation of the potential use of MIOX as a kidney-specific enzyme in the early diagnosis of AKI.

Urinary Neutrophil Gelatinase-Associated Lipocalin as a Predictor of Acute Kidney Injury, Severe Kidney Injury, and the Need for Renal Replacement Therapy in the Intensive Care Unit

Background

Recent attempts were made to identify early indicators of acute kidney injury (AKI) in order to accelerate treatment and hopefully improve outcomes. This study aims to assess the value of urinary neutrophil gelatinase-associated lipocalin (uNGAL) as a predictor of AKI, severe AKI, and the need for renal replacement therapy (RRT).

Methods

We conducted a prospective study and included adults admitted to our intensive care unit (ICU) at King Abdulaziz University Hospital (KAUH), between May 2012 and June 2013, who had at least 1 major risk factor for AKI. They were followed up throughout their hospital stay to identify which potential characteristics predicted any of the above 3 outcomes. We collected information on patients’ age and gender, the Acute Physiology And Chronic Health Evaluation, version II (APACHE II) score, the Sepsis-Related Organ Failure Assessment (SOFA) score, serum creatinine and cystatin C levels, and uNGAL. We compared ICU patients who presented with any of the 3 outcomes with others who did not.

Results

We included 75 patients, and among those 21 developed AKI, 18 severe AKI, and 17 required RRT. Bivariate analysis revealed intergroup differences for almost all clinical variables (e.g., patients with AKI vs. patients without AKI); while multivariate analysis identified mean arterial pressure as the only predictor for AKI (p < 0.001) and the SOFA score (p = 0.04) as the only predictor for severe AKI. For RRT, day 1 maximum uNGAL was the stronger predictor (p < 0.001) when compared to admission diagnosis (p = 0.014). Day 1 and day 2 maximum uNGAL levels were good and excellent predictors for future RRT, but only fair to good predictors for AKI and severe AKI.

Conclusions

Maximum urine levels of uNGAL measured over the first and second 24 h of an ICU admission were highly accurate predictors of the future need for RRT, however less accurate at detecting early and severe AKI.

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.

Milk fat globule-epidermal growth factor-factor VIII attenuates sepsis-induced acute kidney injury

BACKGROUND

Acute kidney injury (AKI) is most commonly caused by sepsis in critically ill patients, and it is associated with high morbidity and mortality. The pathophysiology of sepsis-induced AKI is generally accepted to include direct inflammatory injury, endothelial cell dysfunction, and apoptosis. Milk fat globule-epidermal growth factor-factor VIII (MFG-E8) is a secretory glycoprotein with a known role in the enhancement of apoptotic cell clearance and regulation of inflammation. We hypothesize that administration of recombinant mouse MFG-E8 (rmMFG-E8) can protect mice from kidney injuries caused by sepsis.

METHODS

Sepsis was induced in 8-wk-old male C57BL/6 mice by cecal ligation and puncture (CLP). rmMFG-E8 or phosphate-buffered saline (vehicle) was injected intravenously at a dosage of 20 μg/kg body weight at time of CLP (n = 5-8 mice per group). After 20 h, serum and renal tissue were harvested for various analyses. The renal injury markers blood urea nitrogen (BUN) and creatinine were determined by enzymatic and chemical reactions, respectively. The gene expression analysis was carried out by real-time quantitative polymerase chain reaction.

RESULTS

At 20 h after CLP, serum levels of BUN and creatinine were both significantly increased in the vehicle group compared with the sham group, whereas the mice treated with rmMFG-E8 had a significant reduction in BUN and creatinine levels by 28% and 24.1%, respectively (BUN: 197.7 ± 23.6 versus 142.3 ± 20.7 mg/dL; creatinine: 0.83 ± 0.12 versus 0.63 ± 0.06 mg/dL; P < 0.05). Expressions of novel biomarkers of renal tissue injury neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 were also significantly downregulated by 58.2% and 95%, respectively, after treatment with rmMFG-E8. Proinflammatory cytokine interleukin-6 and tumor necrosis factor-α messenger RNA (mRNA) were significantly reduced by 50.8% and 50.3%, respectively, in rmMFG-E8-treated mice compared with vehicle-treated mice. The mRNA levels of the chemokines keratinocyte chemoattractant and macrophage inhibitory protein-2 were reduced by 85.1% and 78%, respectively, in mice treated with rmMFG-E8 compared with the vehicle mice. In addition, the expression of intercellular cell adhesion molecule-1 and platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31) mRNA was downregulated by 35.6% and 77.8%, respectively, in rmMFG-E8-treated mice compared with the vehicle animals (P < 0.05).

CONCLUSIONS

Treatment with rmMFG-E8 reduces renal tissue injury induced by sepsis through inhibiting the production of proinflammatory cytokines and chemokine, as well as through the activation of endothelial cells. Thus, MFG-E8 may have a therapeutic potential for treating AKI induced by sepsis.

Non-traumatic rhabdomyolysis: Background, laboratory features, and acute clinical management

Rhabdomyolysis is a relatively rare condition, but its clinical consequences are frequently dramatic in terms of both morbidity and mortality. Although no consensus has been reached so far about the precise definition of this condition, the term rhabdomyolysis describes a rapid breakdown of striated, or skeletal, muscle. It is hence characterized by the rupture and necrosis of muscle fibers, resulting in release of cell degradation products and intracellular elements within the bloodstream and extracellular space. Notably, the percentage of patients with rhabdomyolysis who develop acute kidney injury, the most dramatic consequence, varies from 13% to over 50% according to both the cause and the clinical and organizational setting where they are diagnosed. Despite direct muscle injury (i.e., traumatic rhabdomyolysis) remains the most common cause, additional causes, frequently overlapping, include hypoxic, physical, chemical or biological factors. The conventional triad of symptoms includes muscle pain, weakness and dark urine. The laboratory diagnosis is essentially based on the measurement of biomarkers of muscle injury, being creatine kinase (CK) the biochemical "gold standard" for diagnosis, and myoglobin the "gold standard" for prognostication, especially in patients with non-traumatic rhabdomyolysis. The essential clinical management in the emergency department is based on a targeted intervention to manage the underlying cause, combined with infusion of fluids and eventually sodium bicarbonate. We will present and discuss in this article the pathophysiological and clinical features of non-traumatic rhabdomyolysis, focusing specifically on Emergency Department (ED) management.

Plasma Neutrophil Gelatinase-Associated Lipocalin as a Marker for Prediction of 3-Month Graft Survival after Kidney Transplantation

BACKGROUND

Ischemic injury during organ transplantation increases the risk of acute and chronic rejections by promoting alloimmune responses. Measurement of neutrophil gelatinase-associated lipocalin (NGAL) immediately after kidney transplantation may be promising for early detection of ischemic injuries to allograft.

OBJECTIVE

This study assessed possible predictive values of plasma NGAL levels during first hours after kidney transplantation for graft loss within the first 3 months after transplantation.

METHODS

45 kidney transplant recipients were classified into those without graft loss or with graft loss during 3 months after transplantation. Plasma NGAL levels were measured before and at 2, 6, 12, 24 and 96 hours after transplantation. Serum creatinine concentration was assessed daily during hospitalization and at 1, 2, and 3 months post-transplantation.

RESULTS

Serum creatinine and plasma NGAL levels were consistently higher in patients with graft loss compared with those without graft loss. At 2, 24, and 96 hours after transplantation, plasma NGAL concentration was significantly higher in patients who developed allograft loss within 3 months post-transplantation. The cutoff point of plasma NGAL at 2, 24, and 96 hours after transplantation for prediction of graft loss was 304.5 ng/mL (sensitivity of 71.4%, and specificity of 73.7%), 207.8 ng/mL(sensitivity of 85.7%, and specificity of 60.5%), and 184 ng/mL (sensitivity of 85.7%, and specificity of 71.1%), respectively.

CONCLUSION

Plasma NGAL levels at 2, 24, and 96 hours after transplantation can predict 3-month graft loss with fair sensitivity and specificity.

The Usefulness of Determining Neutrophil Gelatinase-Associated Lipocalin Concentration Excreted in the Urine in the Evaluation of Cyclosporine A Nephrotoxicity in Children with Nephrotic Syndrome

Introduction. The use of cyclosporine (CsA) in the treatment of nephrotic syndrome (NS) contributed to a significant reduction in the amount of corticosteroids used in therapy and its cumulative side effects. One of the major drawbacks of CsA therapy is its nephrotoxicity. Prolonged CsA treatment protocols require sensitive, easily available, and simple to measure biomarkers of nephrotoxicity. NGAL is an antibacterial peptide, excreted by cells of renal tubules in response to their toxic or inflammatory damage. Aim of the Study. The aim of this study was to assess the suitability of the NGAL concentration in the urine as a potential biomarker of the CsA nephrotoxicity. Material and Methods. The study was performed on a group of 31 children with NS treated with CsA. The control group consisted of 23 children diagnosed with monosyptomatic enuresis. The relationship between NGAL excreted in urine and the time of CsA treatment, concentration of CsA in blood serum, and other biochemical parameters was assessed. Results. The study showed a statistically significant positive correlation between urine NGAL concentration and serum triglycerides concentration and no correlation between C0 CsA concentration and other observed parameters of NS. The duration of treatment had a statistically significant influence on the NGAL to creatinine ratio. Conclusions. NGAL cannot be used alone as a simple CsA nephrotoxicity marker during NS therapy. Statistically significant correlation between NGAL urine concentration and the time of CsA therapy indicates potential benefits of using this biomarker in the monitoring of nephrotoxicity in case of prolonged CsA therapy.

Improved safety and efficacy of 213Bi-DOTATATE-targeted alpha therapy of somatostatin receptor-expressing neuroendocrine tumors in mice pre-treated with L-lysine

Background

Targeted alpha therapy (TAT) offers advantages over current β-emitting conjugates for peptide receptor radionuclide therapy (PRRT) of neuroendocrine tumors. PRRT with ¹⁷⁷Lu-DOTATATE or ⁹⁰Y-DOTATOC has shown dose-limiting nephrotoxicity due to radiopeptide retention in the proximal tubules. Pharmacological protection can reduce renal uptake of radiopeptides, e.g., positively charged amino acids, to saturate in the proximal tubules, thereby enabling higher radioactivity to be safely administered. The aim of this preclinical study was to evaluate the therapeutic effect of ²¹³Bi-DOTATATE with and without renal protection using L-lysine in mice. Tumor uptake and kinetics as a function of injected mass of peptide (range 0.03–3 nmol) were investigated using ¹¹¹In-DOTATATE. These results allowed estimation of the mean radiation absorbed tumor dose for ²¹³Bi-DOTATATE. Pharmacokinetics and dosimetry of ²¹³Bi-DOTATATE was determined in mice, in combination with renal protection. A dose escalation study with ²¹³Bi-DOTATATE was performed to determine the maximum tolerated dose (MTD) with and without pre-administration of l-lysine as for renal protection. Neutrophil gelatinase-associated lipocalin (NGAL) served as renal biomarker to determine kidney injury.

Results

The maximum mean radiation absorbed tumor dose occurred at 0.03 nmol and the minimum at 3 nmol. Similar mean radiation absorbed tumor doses were determined for 0.1 and 0.3 nmol with a mean radiation absorbed dose of approximately 0.5 Gy/MBq ²¹³Bi-DOTATATE. The optimal mass of injected peptide was found to be 0.3 nmol. Tumor uptake was similar for ¹¹¹In-DOTATATE and ²¹³Bi-DOTATATE at 0.3 nmol peptide. Lysine reduced the renal uptake of ²¹³Bi-DOTATATE by 50% with no effect on the tumor uptake. The MTD was <13.0 ± 1.6 MBq in absence of l-lysine and 21.7 ± 1.9 MBq with l-lysine renal protection, both imparting an LD₅₀ mean renal radiation absorbed dose of 20 Gy. A correlation was found between the amount of injected radioactivity and NGAL levels.

Conclusions

The therapeutic potential of ²¹³Bi-DOTATATE was illustrated by significantly decreased tumor burden and improved overall survival. Renal protection with l-lysine immediately prior to TAT with ²¹³Bi-DOTATATE prolonged survival providing substantial evidence for pharmacological nephron blockade to mitigate nephrotoxicity.

Electronic supplementary material

The online version of this article (doi:10.1186/s13550-016-0240-5) contains supplementary material, which is available to authorized users.

The Kidney in Critical Cardiac Disease: Proceedings From the 10th International Conference of the Pediatric Cardiac Intensive Care Society

The field of cardiac intensive care continues to advance in tandem with congenital heart surgery. The focus of intensive care unit care has now shifted to that of morbidity reduction and eventual elimination. Acute kidney injury (AKI) after cardiac surgery is associated with adverse outcomes, including prolonged intensive care and hospital stays, diminished quality of life, and increased long-term mortality. Acute kidney injury occurs frequently, complicating the care of both postoperative patients and those with heart failure. Patients who become fluid overloaded and/or require dialysis are at high risk of mortality, but even minor degrees of AKI portend a significant increase in mortality and morbidity. Clinicians continue to seek methods of early diagnosis and risk stratification of AKI to prevent its adverse sequelae. Previous conventional wisdom that survivors of AKI fully recover renal function without subsequent consequences may be flawed.

Acute Kidney Injury and Cardiorenal Syndromes in Pediatric Cardiac Intensive Care

OBJECTIVES

The objectives of this review are to discuss the definition, diagnosis, and pathophysiology of acute kidney injury and its impact on immediate, short-, and long-term outcomes. In addition, the spectrum of cardiorenal syndromes will be reviewed including the pathophysiology on this interaction and its impact on outcomes.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSION

The field of cardiac intensive care continues to advance in tandem with congenital heart surgery. As mortality has become a rare occurrence, the focus of cardiac intensive care has shifted to that of morbidity reduction. Acute kidney injury adversely impact outcomes of patients following surgery for congenital heart disease as well as in those with heart failure (cardiorenal syndrome). Patients who become fluid overloaded and/or require dialysis are at a higher risk of mortality, but even minor degrees of acute kidney injury portend a significant increase in mortality and morbidity. Clinicians continue to seek methods of early diagnosis and risk stratification of acute kidney injury to prevent its adverse sequelae.

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.

Diagnosis and prognosis of neutrophil gelatinase-associated lipocalin for acute kidney injury with sepsis: a systematic review and meta-analysis

Background

Neutrophil gelatinase-associated lipocalin (NGAL) has been identified as an early biomarker for prediction of acute kidney injury (AKI). However, the utility of NGAL to predict the occurrence of AKI in septic patients remains controversial. We performed a systematic review and meta-analysis to evaluate the evidence on diagnosis of sepsis AKI and the prediction of other clinical outcomes.

Method

The MEDLINE, EMBASE, Cochrane Library, Wanfang, and CNKI databases were systematically searched up to August 19, 2015. Quality assessment was applied by using the Quality Assessment for Studies of Diagnostic Accuracy (QUADAS-2) tool. The diagnostic performance of NGAL for the prediction of AKI in sepsis was evaluated using pooled estimates of sensitivity, specificity, likelihood ratio, and diagnostic odds ratio (DOR), as well as summary receiver operating characteristic curves (SROC).

Results

Fifteen studies with a total of 1,478 patients were included in the meta-analysis. For plasma NGAL, the pooled sensitivity and specificity with corresponding 95 % confidence intervals (CI) were 0.83 (95 % CI: 0.77 − 0.88) and 0.57 (95 % CI: 0.54 − 0.61), respectively. The pooled positive likelihood ratio (PLR) was 3.10 (95 % CI: 1.57 − 6.11) and the pooled negative likelihood ratio (NLR) was 0.24 (95 % CI: 0.13 − 0.43). The pooled DOR was 14.72 (95 % CI: 6.55 − 33.10) using a random effects model. The area under the curve (AUC) for SROC to summarize diagnostic accuracy was 0.86. For urine NGAL, the pooled sensitivity, specificity, PLR, NLR, DOR, and AUC values were 0.80 (95 % CI: 0.77 − 0.83), 0.80 (95 % CI: 0.77 − 0.83), 4.42 (95 % CI: 2.84 − 6.89), 0.21 (95 % CI: 0.13 − 0.35), 24.20 (95 % CI: 9.92 − 59.05) and 0.90, respectively. Significant heterogeneity was explored as a potential source. There was no notable publication bias observed across the eligible studies. NGAL for prediction of renal replacement therapy (RRT) and mortality associated with AKI in septic patients were also evaluated.

Conclusion

To a certain extent, NGAL is not only an effective predictive factor for AKI in the process of sepsis, but also shows potential predictive value for RRT and mortality. However, future trials are needed to clarify this controversial issue.

Clinical Issues and Controversies in Heart Failure and Transplantation

Heart failure is a common problem among children admitted in the intensive care unit and is associated with significant morbidity and mortality. As such, the 2014 meeting of the Pediatric Cardiac Intensive Care Society included a session on Clinical Controversies in Heart Failure and Transplantation. This review contains the summaries of the podium presentations of this session and will cover some of the challenging aspects of caring for these patients including medical and mechanical support, fluid overload states, high-risk populations including those after heart transplantation, and end-of-life considerations.

NephroCheck data compared to serum creatinine in various clinical settings

BACKGROUND

Acute kidney injury is frequently observed at the intensive care unit, after surgery, and after toxic drug administration. A rise in serum creatinine and a fall in urine output are consequences of much earlier injury to the most sensitive part of tubular cells located at the proximal tubule. The aim of the present study was to investigate the course of two cell-cycle arrest urinary biomarkers compared to serum creatinine in four clinical settings: ischemic reperfusion injury, cardiac failure, severe acute kidney injury, and chemotherapy-induced kidney injury.

METHODS

A recently developed bedside test known as NephroCheck measures two urinary parameters: insulin-like growth factor binding protein 7 (IGFBP7) and tissue inhibitor of metalloproteinase-2 (TIMP-2). The test is based on a sandwich immunoassay technique. The final test output, labeled AKIRisk, is shown as a numeric result.

RESULTS

This report revealed that [IGFBP7] · [TIMP-2] in urine rise rapidly prior to any change in serum creatinine. A unique feature of all four clinical settings is that a rapid decline predicts the recovery of kidney function. Besides, a subclinical kidney injury might be detected by the test.

CONCLUSION

This bedside test detects biomarkers of renal injury. A rapid decline in AKIRisk was associated with the restoration of kidney function, whereas a prolonged high AKIRisk score was associated with end-stage renal disease. However, the dynamics seem to differ, depending on the cause and the extent of injury. Further studies will be needed to clarify the issue.