Urinary netrin-1 is an early predictive biomarker of acute kidney injury after cardiac surgery

Transient renal tubular injury among children and adolescents during diabetic ketoacidosis: severity, renal perfusion, and urinary netrin- 1 interplay

Acute kidney injury (AKI) has been reported during diabetic ketoacidosis (DKA). Evidence regarding tubulopathy is less established, with its pathophysiology, risk determinants, and short-term outcome to be unraveled. Hence, this study aimed to assess renal tubular functions during DKA, its short-term outcome, and its relation with urinary Netrin-1, DKA severity, and renal perfusion indices. Forty children and adolescents (20 with moderate and 20 with severe DKA) were assessed for urine output (UOP), blood pressure, blood glucose, HbA1c, and urinary Netrin-1, with calculation of serum osmolality and estimated glomerular filtration rate (eGFR). Renal pulsatility and resistivity indices were assessed by renal duplex. Reevaluation was done on days 3 and 14. Sixteen children and adolescents had tubular proteinuria during DKA (40%). Their mean urine output (UOP) during DKA was 14.03 cc/kg/h, and their mean urinary Netrin-1 was 836.9 ng/ml. A significant improvement was observed in the UOP, protein/creatinine ratio, urinary netrin, and serum osmolality after the resolution of DKA accompanied by a significant decrease in renal resistivity and pulsatility indices (p < 0.05). A significant positive correlation was found between tubular proteinuria during DKA and urinary Netrin-1, renal pulsatility, and resistivity indices (p < 0.05). Multivariate regression analysis revealed that serum PH and urinary Netrin-1 were the most significant independent variables associated with tubular proteinuria among children and adolescents during DKA.

CONCLUSION

Transient renal tubulopathy occurs during DKA manifested by tubular proteinuria, polyuria, and hypokalemia; that is correlated with DKA severity, renal perfusion indices, and urinary Netrin-1 and reversible by day 14 post-DKA. Netrin-1 could serve as a potential therapeutic target for DKA-associated tubulopathy.

WHAT IS KNOWN

• Diabetic ketoacidosis (DKA) is a severe acute complication of diabetes mellitus, with negative effect on multiple body organs. • Studies increasingly suggest acute kidney injury during DKA, however, data about renal tubular injury during DKA, it's pathophysiology, risk determinants and short term outcomes are still unclear.

WHAT IS NEW

• Transient renal tubulopathy was reported in 40 % the studied children and adolescents during DKA manifested by proteinuria, polyurea, and hypokalemia. • This tubulopathy that was correlated with DKA severity, renal perfusion indices and urinary Netrin-1 and totally reversible by day 14 post DKA.

Perioperative Acute Kidney Injury: Diagnosis, Prediction, Prevention, and Treatment

In this review, the authors define acute kidney injury in the perioperative setting, describe the epidemiologic burden, discuss procedure-specific risk factors, detail principles of management, and highlight areas of ongoing controversy and research.

Renal dysfunction in surgical patients

PURPOSE OF REVIEW

To provide an overview of the current diagnostic criteria for acute kidney injury (AKI) including their limitations and to discuss prevention and treatment approaches in the perioperative setting.

RECENT FINDINGS

AKI is common in the perioperative period and is associated with worse short- and long-term outcomes. Current definitions of AKI have several limitations and lead to delayed recognition of kidney dysfunction which is why novel diagnostic approaches by using renal biomarkers may be helpful. In general, prevention of the development and progression of AKI is vital as a causal treatment for AKI is currently not available. Optimization of kidney perfusion and avoidance of nephrotoxic drugs reduce the occurrence of AKI in surgical patients. Angiotensin II as a new vasopressor, the use of remote ischemic preconditioning, and amino acids may be approaches with a positive effect on the kidneys.

SUMMARY

Evidence suggests that the implementation of supportive measures in patients at high risk for AKI might reduce the occurrence of AKI. Novel biomarkers can help allocating resources by detecting patients at high risk for AKI.

The usefulness of urinary netrin-1 determination as an early marker of acute kidney injury in children after cardiac surgery

Introduction

Netrin-1 (NTN-1) is an anti-inflammatory protein secreted by proximal tubule epithelial cells in reaction to hypoxic or toxic injury. We determined the utility of urinary NTN-1 as an early marker for detecting acute kidney injury (AKI) in patients after cardiac surgery.

Material and methods

Our study included 40 children at age 1-36 months and 20 healthy controls. We measured serum creatinine and urinary NTN-1 in patients who underwent cardiac surgery with cardiopulmonary bypass (CPB).

Results

Urinary NTN-1 was higher in the study group than in the control group. The detection rate of urinary NTN-1 was higher before surgery than 6 and 24 h after (55%, 27.5%, and 32.5%, respectively). We found no correlations between NTN-1 at any point and ΔeGFR, decline in eGFR, or AKI after 48 h. The initial NTN-1/creatinine ratio negatively correlated with ΔGFR (r = -0.36, p = 0.031), NTN-1/creatinine ratio after 24 h did not correlate with aortic clamping time, CPB time, ΔGFR. In our study, AKI occurred in 12.5% of patients and none required renal replacement therapy (RRT). The occurrence of AKI correlated with CPB time (r = 0.35, p = 0.027) and aortic clamping time (r = 0.44, p = 0.005). NTN-1 concentration and NTN-1/creatinine ratio in the AKI group were not significantly higher preoperatively and 24 h post-surgery than in patients without AKI.

Conclusions

The role of urinary NTN-1 in children after cardiac surgery as an early marker of AKI was not confirmed. No factors affecting the NTN-1/creatinine ratio were found in the study group. Patients who have longer CPB time and aortic clamping time belong to the high-risk group of AKI after surgery.

Cardiac Surgery-Associated Acute Kidney Injury

AKI is a common and serious complication of cardiac surgery that has a significant impact on patient morbidity and mortality. The Kidney Disease Improving Global Outcomes definition of AKI is widely used to classify and identify AKI associated with cardiac surgery (cardiac surgery-associated AKI [CSA-AKI]) on the basis of changes in serum creatinine and/or urine output. There are various preoperative, intraoperative, and postoperative risk factors for the development of CSA-AKI which should be recognized and addressed as early as possible to expedite its diagnosis, reduce its occurrence, and prevent or ameliorate its devastating complications. Crucial issues are the inaccuracy of serum creatinine as a surrogate parameter of kidney function in the perioperative setting of cardiothoracic surgery and the necessity to discover more representative markers of the pathophysiology of AKI. However, except for the tissue inhibitor of metalloproteinase-2 and insulin-like growth factor binding protein 7 ratio, other diagnostic biomarkers with an acceptable sensitivity and specificity are still lacking. This article provides a comprehensive review of various aspects of CSA-AKI, including pathogenesis, risk factors, diagnosis, biomarkers, classification, prevention, and treatment management.

Urinary L-FABP as an Early Biomarker for Pediatric Acute Kidney Injury Following Cardiac Surgery with Cardiopulmonary Bypass: A Systematic Review and Meta-Analysis

Acute kidney injury (AKI) following surgery with cardiopulmonary bypass (CPB-AKI) is common in pediatrics. Urinary liver-type fatty acid binding protein (uL-FABP) increases in some kidney diseases and may indicate CPB-AKI earlier than current methods. The aim of this systematic review with meta-analysis was to evaluate the potential role of uL-FABP in the early diagnosis and prediction of CPB-AKI. Databases Pubmed/MEDLINE, Scopus, and Web of Science were searched on 12 November 2023, using the MeSH terms "Children", "CPB", "L-FABP", and "Acute Kidney Injury". Included papers were revised. AUC values from similar studies were pooled by meta-analysis, performed using random- and fixed-effect models, with p < 0.05. Of 508 studies assessed, nine were included, comprising 1658 children, of whom 561 (33.8%) developed CPB-AKI. Significantly higher uL-FABP levels in AKI versus non-AKI patients first manifested at baseline to 6 h post-CPB. At 6 h, uL-FABP correlated with CPB duration (r = 0.498, p = 0.036), postoperative serum creatinine (r = 0.567, p < 0.010), and length of hospital stay (r = 0.722, p < 0.0001). Importantly, uL-FABP at baseline (AUC = 0.77, 95% CI: 0.64-0.89, n = 365), 2 h (AUC = 0.71, 95% CI: 0.52-0.90, n = 509), and 6 h (AUC = 0.76, 95% CI: 0.72-0.80, n = 509) diagnosed CPB-AKI earlier. Hence, higher uL-FABP levels associate with worse clinical parameters and may diagnose and predict CPB-AKI earlier.

Insights from the neural guidance factor Netrin-1 into neurodegeneration and other diseases

Netrin-1 was initially discovered as a neuronal growth cue for axonal guidance, and its functions have later been identified in inflammation, tumorigenesis, neurodegeneration, and other disorders. We have recently found its alterations in the brains with Alzheimer's disease, which might provide important clues to the mechanisms of some unique pathologies. To provide better understanding of this promising molecule, we here summarize research progresses in genetics, pathology, biochemistry, cell biology and other studies of Netrin-1 about its mechanistic roles and biomarker potentials with an emphasis on clinical neurodegenerative disorders in order to expand understanding of this promising molecular player in human diseases.

CXCL10 is a prognostic marker for pancreatic adenocarcinoma and tumor microenvironment remodeling

BACKGROUND

The tumor microenvironment (TME) plays a crucial role in the progression of pancreatic adenocarcinoma (PAAD). However, challenges remain regarding the role played by TME associated genes in the prognosis of PAAD.

METHODS

The scores of tumor infiltrating immune cells (TICs), the immune and stroma scores of 182 PAAD patients in the Cancer Genome Atlas (TCGA) database were determined using CIBERSORT and ESTIMATE calculations. The final genes were identified by protein-protein interaction (PPI) networks and univariate Cox regression of differentially expressed genes. Finally, the correlation between gene expression and TCGA and clinical characteristics of patients in local hospital database was discussed. Gene set enrichment analysis (GSEA), the association between CXCL10 expression and TICs components were conducted.

RESULTS

In TCGA database and local hospital data, CXCL10 expression was correlated with the survival rate and TNM classification of patients with PAAD. Immune-related activities were enriched in the CXCL10 high expression group, while metabolic pathways were enriched in the CXCL10 low expression group. The expression of CXCL10 correlated with the proportion of TICs. CXCL10 expression was correlated with the proportion of TICs.

CONCLUSION

CXCL10 is a potential prognostic marker for PAAD and provide additional insights into the treatment of PAAD based on TME transformation. However, more independent experimentation with the CXCL10 is need.

Biomarker-Based Prediction of Survival and Recovery of Kidney Function in Acute Kidney Injury

BACKGROUND

Acute kidney injury (AKI) affects increasing numbers of hospitalized patients; the prognosis remains poor. The diagnosis is still based on the 2012 published KDIGO criteria. Numerous new AKI biomarkers have been identified in recent years; they either reflect impaired excretory function or structural damage. The majority of markers are useful for AKI recognition under certain circumstances. Fewer data are available on the role of biomarkers in the prediction of in-hospital survival and renal recovery post-AKI. The current article is intended to provide information about these two aspects.

SUMMARY

The following databases were screened: PubMed, Web of Science, Cochrane Library, Scopus. The period lasted from 2000 until 2022. The following terms were applied: "AKI" AND "biomarker" AND "survival" OR "mortality" OR "recovery of kidney function" OR "renal recovery" OR "kidney recovery". The following terms were used for additional literature search: "TIMP-2" AND "IGFBP7" and "RNA biomarker" AND "hematology". Regarding mortality, exclusively those studies were selected that addressed the in-hospital mortality. Nine (9) studies were identified that evaluated biomarker-based prediction of in-hospital mortality and/or of recovery of kidney function (ROKF). A homogenous definition of ROKF is however missing yet. Currently, some biomarkers, measured early during the course of the disease, are associated with increased mortality risk and/or with a higher chance of renal recovery.

KEY MESSAGES

The literature provides only a few biomarker-related studies that address the issues of mortality and recovery. The definition of ROKF needs to be homogenized.

Netrin-1 Overexpression Induces Polycystic Kidney Disease: A Novel Mechanism Contributing to Cystogenesis in Autosomal Dominant Polycystic Kidney Disease

Despite recent advances in understanding the pathogenesis of polycystic kidney disease (PKD), the underlying molecular mechanisms involved in cystogenesis are not fully understood. This study describes a novel pathway involved in cyst formation. Transgenic mice overexpressing netrin-1 in proximal tubular cells showed increased production and urinary excretion of netrin-1. Although no cysts were detectable immediately after birth, numerous small cysts were evident by the age of 4 weeks, and disease was accelerated along with age. Surprisingly, cyst formation in the kidney was restricted to male mice, with 80% penetrance. However, ovariectomy induced kidney cyst growth in netrin-1-overexpressing female mice. Cyst development in males was associated with albuminuria and polyuria and increased cAMP excretion in netrin-1 transgenic mice. Netrin-1 overexpression significantly increased extracellular signal-regulated kinase and focal adhesion kinase phosphorylation and vimentin expression. Interestingly, p53 expression was increased but in an inactive form. Furthermore, netrin-1 expression was increased in cystic epithelia and urine of various rodent models of PKD. siRNA-mediated suppression of netrin-1 significantly reduced cyst growth and improved kidney function in netrin-1 transgenic mice and in two genetic animal models of PKD. Together, these data demonstrate that netrin-1 up-regulation induced cyst formation in autosomal dominant PKD.

[Netrin-1, a novel antitumoral target]

Netrin-1, a secreted molecule that was first described for its role in guidance during embryogenesis, was then brought to light for its overexpression in a large number of aggressive cancers. Netrin-1 is a ligand of "dependence receptors". In adults, the interaction between Netrine-1 and these receptors triggers the survival, proliferation, and migration of different cell types. This will confer better survival properties to tumor cells, making them more prone to form aggressive tumors. A recently developed novel therapy aims at inhibiting the binding of Netrin-1 to these receptors in order to trigger cell death by apoptosis. This article presents a review of the functional characteristics of the Netrin-1 molecule, and the potential effects of a novel targeted therapy against Netrin-1 that could lead to very promising results in combination with conventional anti-cancer treatments.

New Biomarkers in Early Diagnosis of Acute Kidney Injury in Children

Acute Kidney Injury (AKI) is a common condition with a high risk of mortality and morbidity, so, early diagnosis and management of AKI is very important in clinical practice. Despite significant progress in the management of AKI, it still carries high morbidity and mortality. BUN and serum creatinine are not very sensitive nor specific for the diagnosis of AKI because they are affected by many renal and non-renal factors that are independent of kidney injury or kidney function and change significantly only after significant kidney injury and with a substantial time delay. Detection of biomarkers of AKI made predominantly by the injured kidney tissue are essential for the early diagnosis of AKI. An ideal biomarker should be one that could be easily measured, with no interference with other biologic variables, and be able to clarify early phases of kidney damage. The most common biomarkers studied are Neutrophil Gelatinase-Associated Lipocalin (NGAL), Interleukin-18 (IL-18), Kidney Injury Molecule-1 (KIM-1), Cystatin-C, L type Fatty Acid-Binding Protein (L-FABP), N-Acetyl-β-D Glucosaminidase (NAG), netrin-1, vanin-1, and Monocyte Chemoattractant Protein-1 (MCP-1) and calprotectin.

Netrin-1: A Modulator of Macrophage Driven Acute and Chronic Inflammation

Netrins belong to the family of laminin-like secreted proteins, which guide axonal migration and neuronal growth in the developing central nervous system. Over the last 20 years, it has been established that netrin-1 acts as a chemoattractive or chemorepulsive cue in diverse biological processes far beyond neuronal development. Netrin-1 has been shown to play a central role in cell adhesion, cell migration, proliferation, and cell survival in neuronal and non-neuronal tissue. In this context, netrin-1 was found to orchestrate organogenesis, angiogenesis, tumorigenesis, and inflammation. In inflammation, as in neuronal development, netrin-1 plays a dichotomous role directing the migration of leukocytes, especially monocytes in the inflamed tissue. Monocyte-derived macrophages have long been known for a similar dual role in inflammation. In response to pathogen-induced acute injury, monocytes are rapidly recruited to damaged tissue as the first line of immune defense to phagocyte pathogens, present antigens to initiate the adaptive immune response, and promote wound healing in the resolution phase. On the other hand, dysregulated macrophages with impaired phagocytosis and egress capacity accumulate in chronic inflammation sites and foster the maintenance-and even the progression-of chronic inflammation. In this review article, we will highlight the dichotomous roles of netrin-1 and its impact on acute and chronic inflammation.

PMN-derived netrin-1 attenuates cardiac ischemia-reperfusion injury via myeloid ADORA2B signaling

Previous studies implicated the neuronal guidance molecule netrin-1 in attenuating myocardial ischemia-reperfusion injury. However, the tissue-specific sources and receptor signaling events remain elusive. Neutrophils are among the first cells responding to an ischemic insult and can be associated with tissue injury or rescue. We found netrin-1 levels were elevated in the blood of patients with myocardial infarction, as well as in mice exposed to myocardial ischemia-reperfusion. Selectively increased infarct sizes and troponin levels were found in Ntn1loxP/loxP Lyz2 Cre+ mice, but not in mice with conditional netrin-1 deletion in other tissue compartments. In vivo studies using neutrophil depletion identified neutrophils as the main source for elevated blood netrin-1 during myocardial injury. Finally, pharmacologic studies using treatment with recombinant netrin-1 revealed a functional role for purinergic signaling events through the myeloid adenosine A2b receptor in mediating netrin-1-elicited cardioprotection. These findings suggest an autocrine signaling loop with a functional role for neutrophil-derived netrin-1 in attenuating myocardial ischemia-reperfusion injury through myeloid adenosine A2b signaling.

Diagnostic efficacy of serum and urinary netrin-1 in the early detection of diabetic nephropathy

This study aimed to assess the diagnostic value of serum and urinary netrin-1 in patients with type 2 diabetes mellitus (T2DM) at different stages of diabetic nephropathy (DN) and to compare its efficacy of estimation in serum with that in the urine. This study was carried out on 135 patients with T2DM and 45 healthy subjects. The patients with diabetes were divided according to urinary albumin creatinine ratio (UACR) into: T2DM with normoalbuminuria, incipient DN with microalbuminuria, and overt DN with macroalbuminuria groups. Serum and urinary levels of netrin-1 were measured by ELISA. The mean levels of serum and urinary netrin-1 were significantly higher in the microalbuminuric and macroalbuminuric patients with DN than those in the normoalbuminuric patients with T2DM, with the highest values detected in macroalbuminuric patients with DN. Urinary netrin-1 level was significantly higher in the normoalbuminuric T2DM group than control group, whereas no significant difference existed regarding serum netrin-1 level. In T2DM groups, the urinary and serum netrin-1 correlated with each other and were independently related to fasting blood glucose, UACR, and estimated glomerular filtration rate. Receiver operating characteristic curve analysis showed that the area under the curve of urinary netrin-1 was 0.916 which is significantly higher than that of serum netrin-1 (0.812) for the detection of incipient DN and reached 0.938 on coestimation of both urinary and serum netrin-1. In conclusion, netrin-1 is a potential diagnostic marker for early detection of DN with its estimation in urine has higher accuracy than that of serum.

Netrin-1 and clusterin: Innovative potential diagnostic biomarkers for early renal damage in β-thalassemia major children

BACKGROUND

Children with β-thalassemia major (β-TM) suffer from tubular dysfunction even before the onset of any renal impairment symptoms and/or clinical signs. Therefore, identifying innovative biomarkers allowing early renal damage detection has focused attention.

AIM

This study aims to preliminary assess Netrin-1(NTN-1) and clusterin (CLU) in β-TM children and explore their possible roles as surrogate noninvasive biomarkers of renal tubular dysfunction.

SUBJECTS AND METHODS

In this study, 40 β-TM children and 30 healthy children were enrolled. Routine serum and urinary biochemical variables were determined. Urinary NTN-1 and CLU levels were measured using ELISA and their mRNA expression in PBMCs were assayed using real-time PCR. Serum TNF-α, MDA levels and GST activity were measured.

RESULTS

Urinary NTN-1 and CLU concentrations and mRNA relative expression levels in PBMCs were significantly increased in β-TM children relative to controls. Oxidative stress and inflammatory markers revealed significant elevation in β-TM children compared to controls. The change in these parameters correlated significantly with other renal parameters. ROC curves analysis showed that urinary NTN-1 and CLU levels are of promising diagnostic performance.

CONCLUSION

Our results suggest that NTN-1 and CLU are qualified as new noninvasive biomarker panels for early detection of renal injury in β-TM children. Moreover, urinary NTN-1 is recommended as a precise one during the clinical practices.

Is Urinary Netrin-1 a Good Marker of Tubular Damage in Preterm Newborns?

There is a lack of a good marker for early kidney injury in premature newborns. In recent publications, netrin-1 seems to be a promising biomarker of kidney damage in different pathological states. The study aimed to measure the urinary level of netrin-1 depending on gestational age. A prospective study involved 88 newborns (I-60 premature newborns, II-28 healthy term newborns). Additionally, premature babies were divided for 2 groups: IA-28 babies born between 30–34 weeks of gestation and IB-32 born at 35–36 weeks. The median urinary concentration of netrin-1 was: IA-(median, Q1–Q3) 63.65 (56.57–79.92) pg/dL, IB-61.90 (58.84–67.17) pg/dL, and II-60.37 (53.77–68.75) pg/dL, respectively. However urinary netrin-1 normalized by urinary concentration of creatinine were IA-547.9 (360.2–687.5) ng/mg cr., IB-163.64 (119.15–295.96) ng/mg cr., and II-81.37 (56.84–138.58) ng/mg cr., respectively and differ significantly between the examined groups (p = 0.00). The netrin-1/creatinine ratio is increased in premature babies. Further studies examining the potential factors influencing kidney function are necessary to confirm its potential value in the diagnosis of subclinical kidney damage in premature newborns.

Urinary netrin-1 concentration in healthy full-term newborns

INTRODUCTION

Monitoring of renal function in acute kidney injury in the pediatric population is complicated by the lack of age-related reference values of new biomarkers. Urinary netrin-1 is a new marker to demonstrate early kidney damage. Netrin-1 has a molecular mass of 72 kDa. It is therefore unlikely that it is filtered by the glomerulus under normal conditions. However, netrin-1 is highly induced after acute and chronic kidney injury and excreted in urine in humans. The aim of the study was to determine the normal concentrations of urinary netrin-1 in healthy full-term newborns.

MATERIAL AND METHODS

The study included 88 healthy full-term neonates (51 boys and 37 girls) born from normal, uncomplicated pregnancies. The concentration of netrin-1 was determined in urine obtained on the first or second day of life with a commercially available ELISA kit.

RESULTS

The urinary concentration of netrin-1 in newborns was independent of gender and time of urine collection. We found a negative correlation between both the urinary netrin-1 concentration and urinary netrin-1 concentration after normalization for urinary creatinine and the birth weight.

CONCLUSIONS

This is the first study showing the urinary netrin-1 concentration in healthy full-term newborns. Future investigation is needed to confirm its potential role as a marker of kidney function in this age group.

Kidney Diseases: The Age of Molecular Markers

Kidney diseases are conditions that increase the morbidity and mortality of those afflicted. Diagnosis of these conditions is based on parameters such as the glomerular filtration rate (GFR), measurement of serum and urinary creatinine levels and equations derived from these measurements (Wasung, Chawla, Madero. Clin Chim Acta 438:350-357, 2015). However, serum creatinine as a marker for measuring renal dysfunction has its limitations since it is altered in several other physiological situations, such as in patients with muscle loss, after intense physical exercise or in people on a high protein diet (Riley, Powers, Welch. Res Q Exerc Sport 52(3):339-347, 1981; Juraschek, Appel, Anderson, Miller. Am J Kidney Dis 61(4):547-554, 2013). Besides the fact that serum creatinine is a marker that indicates glomerular damage, it is necessary the discovery of new biomarkers that reflect not only glomerular damage but also tubular impairment. Recent advances in Molecular Biology have led to the generation or identification of new biomarkers for kidney diseases such as: Acute Kidney Failure (AKI), chronic kidney disease (CKD), nephritis or nephrotic syndrome. There are recent markers that have been used to aid in diagnosis and have been shown to be more sensitive and specific than classical markers, such as neutrophil gelatinase associated lipocalin (NGAL) or kidney injury molecule-1 (KIM-1) (Wasung, Chawla, Madero. Clin Chim Acta 438:350-357, 2015; George, Gounden. Adv Clin Chem 88:91-119, 2019; Han, Bailly, Abichandani, Thadhani, Bonventre. Kidney Int 62(1):237-244, 2002; Fontanilla, Han. Expert Opin Med Diagn 5(2):161-173, 2011). However, early diagnostic biomarkers are still necessary to assist the intervention and monitor of the progression of these conditions.

Recommendations on Acute Kidney Injury Biomarkers From the Acute Disease Quality Initiative Consensus Conference: A Consensus Statement

IMPORTANCE

In the last decade, new biomarkers for acute kidney injury (AKI) have been identified and studied in clinical trials. Guidance is needed regarding how best to incorporate them into clinical practice.

OBJECTIVE

To develop recommendations on AKI biomarkers based on existing data and expert consensus for practicing clinicians and researchers.

EVIDENCE REVIEW

At the 23rd Acute Disease Quality Initiative meeting, a meeting of 23 international experts in critical care, nephrology, and related specialties, the panel focused on 4 broad areas, as follows: (1) AKI risk assessment; (2) AKI prediction and prevention; (3) AKI diagnosis, etiology, and management; and (4) AKI progression and kidney recovery. A literature search revealed more than 65 000 articles published between 1965 and May 2019. In a modified Delphi process, recommendations and consensus statements were developed based on existing data, with 90% agreement among panel members required for final adoption. Recommendations were graded using the Grading of Recommendations, Assessment, Development and Evaluations system.

FINDINGS

The panel developed 11 consensus statements for biomarker use and 14 research recommendations. The key suggestions were that a combination of damage and functional biomarkers, along with clinical information, be used to identify high-risk patient groups, improve the diagnostic accuracy of AKI, improve processes of care, and assist the management of AKI.

CONCLUSIONS AND RELEVANCE

Current evidence from clinical studies supports the use of new biomarkers in prevention and management of AKI. Substantial gaps in knowledge remain, and more research is necessary.

Urine hepcidin, netrin-1, neutrophil gelatinase-associated lipocalin and C-C motif chemokine ligand 2 levels in multicystic dysplastic kidney

Introduction:

Glomerular hyperfiltration may lead to proteinuria and chronic kidney disease in unilateral multicystic dysplastic kidney (MCDK). We aimed to investigate the urine neutrophil-gelatinase-associated lipocalin (NGAL), netrin-1, hepcidin, and C-C motif chemokine ligand-2 (MCP-1/CCL-2) levels in patients with MCDK.

Methods:

Thirty-two patients and 25 controls were included. The urine hepcidin, netrin-1, NGAL, and MCP-1/CCL-2 levels were determined by ELISA.

Results:

The patients had higher serum creatinine (Cr) levels, urine albumin, and netrin-1/ Cr ratio with lower GFR. There were positive correlations between urine protein/Cr, MCP-1/CCL-2/Cr, and netrin-1 with NGAL (r = 0.397, p = 0.031; r = 0.437, p = 0.041, r = 0.323, p = 0.042, respectively). Urine netrin-1/Cr was positively correlated with MCP-1/ CCL-2/Cr (r = 0.356, p = 0.045). There were positive associations between the presence of proteinuria and netrin-1/ Cr, MCP-1/CCL-2/Cr, and NGAL/Cr [Odds ratio (OR): 1.423, p = 0.037, OR: 1.553, p = 0.033, OR: 2.112, p = 0.027, respectively)]. ROC curve analysis showed that netrin-1/Cr, MCP-1/CCL-2/Cr, and NGAL/Cr had high predictive values for determining proteinuria p = 0.027, p = 0.041, p = 0.035, respectively). Urine hepcidin/ Cr was negatively correlated with tubular phosphorus reabsorption and was positively correlated with urine NGAL/Cr (r = -0.418, p = 0.019; r = 0.682, p = 0.000; respectively).

Conclusions:

MCP-1/CCL-2 may play a role in the development of proteinuria in MCDK. Netrin-1 may be a protective factor against proteinuria-induced renal injury. Urine hepcidin/Cr may reflect proximal tubule damage in MCDK. Urine NGAL/Cr may be a predictor of tubule damage by proteinuria.

High Serum Netrin-1 and IL-1β in Elderly Females with ACS: Worse Prognosis in 2-years Follow-up

Fundamento

Vários marcadores têm sido avaliados quanto a um potencial impacto nas decisões clínicas ou na predição de mortalidade na síndrome coronariana aguda (SCA), incluindo Netrina-1 e IL-1β.

Objetivo

Examinamos o valor prognóstico de Netrina-1 e IL-1β em pacientes com SCA (2 anos de acompanhamento).

Métodos

Avaliamos Netrina-1, IL-1β e outros fatores de risco em amostras de soro de 803 pacientes. Curvas de Kaplan-Meier e regressão de Cox foram usadas para análise de óbito por todas as causas, óbito por doenças cardiovasculares (DCV) e desfecho combinado de infarto agudo do miocárdio (IAM) fatal ou novo IAM não fatal, considerando p < 0,05.

Resultados

Houve 115 óbitos por todas as causas, 78 óbitos por DCV e 67 eventos no desfecho combinado. Níveis de Netrina-1 acima da mediana (> 44,8 pg/mL) foram associados a pior prognóstico (óbito por todas as causas e por DCV) em mulheres idosas, mesmo após o ajuste do modelo (HR: 2,08, p = 0,038 e HR: 2,68, p = 0,036). Níveis de IL-1β acima da mediana (> 13,4 pg/mL) em mulheres idosas foram associados a risco aumentado para todos os desfechos após o ajuste (todas as causas - HR: 2,03, p = 0,031; DCV - HR: 3,01, p = 0,013; desfecho combinado - HR: 3,05, p = 0,029). Para homens, não foram observadas associações entre Netrina-1 ou IL-1β e os desfechos.

Conclusão

Níveis séricos elevados de Netrina-1 e IL-1β mostraram associação significativa com pior prognóstico em idosas do sexo feminino. Eles podem ser úteis como indicadores prognósticos em SCA. (Arq Bras Cardiol. 2020; 114(3):507-514)

Netrin-1 works with UNC5B to regulate angiogenesis in diabetic kidney disease

Netrin-1, an axon guidance factor, and its receptor UNC5B play important roles in axonal development and angiogenesis. This study examined netrin-1 and UNC5B expression in kidneys with diabetic kidney disease (DKD) and investigated their roles in angiogenesis. Netrin-1 and UNC5B were upregulated in streptozotocininduced DKD Wistar rats, and their expression was compared with that in healthy controls. However, exogenous netrin-1 in UNC5B-depleted human renal glomerular endothelial cells (HRGECs) inhibited cell migration and tubulogenesis. This effect was likely associated with SRC pathway deactivation. Netrin-1 treatment also eliminated the pro-angiogenic effects of exogenous VEGF-165 on UNC5B-silenced HRGECs. These results indicate that UNC5B antagonizes netrin-1 and that UNC5B upregulation contributes partly to enhancing angiogenesis in DKD. Therefore, introducing exogenous netrin-1 and depleting endogenous UNC5B are potential strategies for reducing the incidence of early angiogenesis and mitigating kidney injury in DKD.

Evaluation of the relationship between short-term glycemic control and netrin-1, a urinary proximal tubular injury marker in children with type 1 diabetes

Background Diabetic nephropathy (DN) is a significant cause of morbidity and mortality in young adults with type 1 diabetes (T1D). Microalbuminuria (MA) is generally considered as the earliest manifestation of DN. However, it has been shown that MA may be temporary and not reflect permanent renal failure. For this reason, sensitive markers are needed for the detection of kidney damage in the early period. Urinary tubular injury markers increase in the early period of diabetes. These tubular markers are rather indicators of acute renal damage. The objective of this study was to measure the urinary netrin-1 level, a marker of tubular injury in children with normoalbuminuric (NA) T1D, and to determine its relationship with short-term fluctuations in blood glucose using fructosamine levels. Methods Netrin-1 levels in spot urine samples from 82 children with T1D (median age 13.6 years) without MA or hypertension and from 59 healthy controls (median age 11.3 years) with a similar distribution of age and body mass index (BMI) were compared. The relationship of the netrin-1 levels with diabetes parameters such as fructosamine, hemoglobin A1c (HbA1c) or duration of diabetes was investigated. Results Urinary netrin-1 level was found to be higher in patients with T1D than in healthy controls (590 [interquartile range (IQR) = 811] pg/mg-creatinine [pg/mg-cr] and 396 [IQR = 742] pg/mg-cr, respectively) (p = 0.03). Urinary netrin-1 was found to correlate with HbA1c (p = 0.007, r = 0.320) and fructosamine (p = 0.04, r = 0.310) but not with average HbA1c in the last year (p = 0.14, r = -0.19), duration of diabetes (p = 0.83, r = 0.02) or other diabetes indices. Conclusions These results support the idea that tubular damage occurs early in the course of diabetes. However, the fact that netrin-1 is related to fructosamine and HbA1c but not to the duration of diabetes or average HbA1c in the last year may suggest that the tubular damage markers are affected by short-term fluctuations in blood glucose.

Urinary and Serum Biomarkers for Prediction of Acute Kidney Injury in Patients Undergoing Liver Transplantation

Acute kidney injury (AKI) is a frequent and serious complication of orthotopic liver transplantation (OLT), with a significant impact on mortality, graft survival, and chronic kidney disease. Currently, the diagnosis of AKI is based on changes in serum creatinine, which is a late marker, usually rising when there is already significant damage to the renal parenchyma. During the last 2 decades, various biomarkers have been studied in many clinical situations, mostly after cardiac surgery, in drug-induced AKI, or in sepsis. The present article summarizes the data on those biomarkers that have been evaluated for the prediction of AKI in patients undergoing OLT.

Netrin-1 alleviates subarachnoid haemorrhage-induced brain injury via the PPARγ/NF-KB signalling pathway

Netrin‐1 (NTN‐1) is a novel drug to alleviate early brain injury following subarachnoid haemorrhage (SAH). However the molecular mechanism of NTN‐1‐mediated protection against early brain injury following SAH remains largely elusive. This study aims to evaluate the effects and mechanisms of NTN‐1 in protecting SAH‐induced early brain injury. The endovascular perforation SAH model was constructed using male C57BL/6J mice, and recombinant NTN‐1 was administrated intravenously. Mortality rates, SAH grade, brain water content, neurological score and neuronal apoptosis were evaluated. The expression of PPARγ, Bcl‐2, Bax and nuclear factor‐kappa B (NF‐κB) were detected by Western blot. Small interfering RNA specific to NTN‐1 receptor, UNC5B, and a selective PPARγ antagonist, bisphenol A diglycidyl ether (BADGE), were applied in combination with NTN‐1. The results suggested that NTN‐1 improved the neurological deficits, reduced the brain water content and alleviated neuronal apoptosis. In addition, NTN‐1 enhanced PPARγ and Bcl‐2 expression and decreased the levels of Bax and NF‐κB. However, the neuroprotection of NTN‐1 was abolished by UNC5B and BADGE. In conclusion, our results demonstrated that NTN‐1 attenuates early brain injury following SAH via the UNC5B PPARγ/NF‐κB signalling pathway.

Biomarkers of Sepsis-Induced Acute Kidney Injury

Sepsis, an infection-induced systemic disease, leads to pathological, physiological, and biochemical abnormalities in the body. Organ dysfunction is caused by a dysregulated host response to infection during sepsis which is a major contributing factor to acute kidney injury (AKI) and the mortality rate for sepsis doubles due to coincidence of AKI. Sepsis-induced AKI is strongly associated with increased mortality and other adverse outcomes. More timely diagnosis would allow for earlier intervention and could improve patient outcomes. Sepsis-induced AKI is characterized by a distinct pathophysiology compared with other diseases and may also have unique patterns of plasma and urinary biomarkers. This concise review summarizes properties and perspectives of the biomarkers for their individual clinical utilization.

Relationship Between Circulating Netrin-1 Concentration, Impaired Fasting Glucose, and Newly Diagnosed Type 2 Diabetes

Background: The protein netrin-1 has demonstrated anti-inflammatory, tissue regeneration, and immune modulation properties. Although inflammation is a major contributing factor in the development of insulin resistance and type 2 diabetes, little is known about a possible relationship between serum netrin-1 and type 2 diabetes. Therefore, we investigated the association between circulating levels of netrin-1 and glycometabolic parameters predictive of type 2 diabetes. Methods: Serum samples were collected from 41 normal controls, 85 subjects with impaired fasting glucose (IFG), and 92 subjects with newly diagnosed type 2 diabetes. Clinical and laboratory parameters were assessed and netrin-1 levels were measured by commercial enzyme-linked immunosorbent assay. Spearman correlation analyses and multivariable-adjusted regression analyses were conducted to examine the relationship between serum netrin-1 levels and glycometabolic parameters. Results: Serum netrin-1 levels in subjects with type 2 diabetes or IFG were significantly higher compared to normal controls (441.0, 436.6, and 275.9 pg/mL, respectively; P for trend < 0.001). Serum netrin-1 levels were significantly positively correlated with fasting glucose, HbA_1c, and insulin resistance index (all Ps < 0.01). Serum netrin-1 levels were independently associated with IFG or type 2 diabetes (standardized β = 0.405, P < 0.001) after adjusting for covariates and potential confounders. In addition, the receiver operating characteristic (ROC) analysis showed that serum netrin-1 levels could identify the presence of IFG and type 2 diabetes with the area under the ROC curve (AUC) of 0.784 (P < 0.001). Conclusions: Our results suggest that elevated serum netrin-1 levels are significantly associated with the presence of IFG and type 2 diabetes.

Serum netrin-1 in relation to gadolinium-enhanced magnetic resonance imaging in early multiple sclerosis

Background

Netrin-1, a secreted laminin-related protein, is known to regulate not only axonal guidance and neuronal cell migration, but also blood–brain barrier integrity and inflammation. Two preliminary studies reported altered serum netrin-1 levels in multiple sclerosis; however, associations with longitudinal clinical and magnetic resonance imaging activity have not been investigated.

Objectives

We aimed to assess serum netrin-1 in multiple sclerosis and controls with respect to disease activity and its temporal dynamics.

Methods

Serum netrin-1 was assessed by enzyme-linked immunosorbent assay in 79 patients with clinically isolated syndrome or multiple sclerosis, and 30 non-inflammatory neurological disease controls. In patients, serum samples were collected immediately prior to gadolinium-enhanced 3 T magnetic resonance imaging at two time points (initial contrast-enhancing gadolinium+ n = 47, non-enhancing gadolinium– n = 32; reference gadolinium– n = 70; median time-lag 1.4, interquartile range 1.0–2.3 years).

Results

Serum netrin-1 levels were similar in clinically isolated syndrome, multiple sclerosis and controls, and gadolinium+ and gadolinium– patients. Among gadolinium+ patients, serum netrin-1 was decreased in clinically active (n = 8) vs non-active patients (n = 39; p = 0.041). Serum netrin-1 showed no temporal dynamics in multiple sclerosis and was unrelated to clinical data.

Conclusions

Serum netrin-1 levels show no multiple sclerosis specific changes and are not sensitive for detection of subclinical disease activity. Netrin-1 changes during relapses may deserve further examination.

Urinary Netrin-1: A New Biomarker for the Early Diagnosis of Renal Damage in Obese Children

OBJECTIVE

Urinary netrin-1 is a new marker to demonstrate early tubular damage. The aim of this study was to determine whether urinary netrin-1 is increased in obese children.

METHODS

A total of 68 normoalbuminuric and normotensive obese patients and 65 controls were included in the study. Urine samples were collected for assessment of urinary phosphorus, sodium, potassium, creatinine, albumin, and netrin-1. Blood samples were collected for measurements of fasting glucose, insulin, lipid, phosphorus, sodium, potassium, and creatinine levels. Homeostatic model assessment insulin resistance index was calculated.

RESULTS

Gender and age were similar between obese and control groups (12.01±3.03 vs. 11.7±3.2 years, p=0.568 and 33 vs. 35 girls, p=0.543, respectively). Obese patients had significantly higher netrin-1 excretion than the controls (841.68±673.17 vs. 228.94±137.25 pg/mg creatinine, p=0.000). Urinary netrin-1 level was significantly higher in obese subjects with insulin resistance compared to those without insulin resistance (1142±1181 vs. 604.9±589.91 pg/mg creatinine, p=0.001).

CONCLUSION

In normotensive and normoalbuminuric obese children, urinary netrin-1 level can increase before onset of albuminuria. Urinary netrin-1 excretion appears to be affected predominantly by insulin resistance and hyperinsulinemia. Urinary netrin-1 may be a new biomarker for determining early tubular injury in obese children.

Evaluation of Netrin-1 Levels and Albuminuria in Patients With Diabetes

BACKGROUND

Netrin-1 is a diagnostic biomarker that has been identified recently for chronic renal failure (CRF) in animal experiments. Netrin-1 levels in urine have been shown to have increased significantly at the acute kidney damage. Human studies on the relation between the CRF and plasma netrin-1 levels have not been found in the literature. This study aimed to investigate whether plasma netrin-1 levels increased in the early stages of the CRF in diabetic patients.

METHODS

Plasma samples from healthy volunteers and diabetic patients with and without microalbuminuria were collected after receiving consent. Netrin-1 in plasma was quantified by enzyme-linked immunosorbent assay and the data were analyzed to determine whether plasma netrin-1 correlates significantly with disease progression.

RESULT

Plasma netrin-1 level in microalbuminuric diabetic patients was significantly higher than in normoalbuminuric diabetic patients and the control group. However, no significant difference between normoalbuminuric patients and control group was determined. Plasma netrin-1 level was significantly associated with albuminuria and estimated glomerular filtration rate, independently of age and sex.

CONCLUSION

This study supports that plasma netrin-1 level increases significantly when glomerular damage occurs in diabetic nephropathy.

Urinary markers of acute kidney injury in newborns with perinatal asphyxia (.)

BACKGROUND

Acute kidney injury (AKI) affects up to 60% of severely asphyxiated neonates. The diagnosis of AKI can be and is further challenged by a lack of good biomarkers. We studied the role of novel markers for AKI, neutrophil gelatinase-associated lipocalin (NGAL), interleukin-8 (IL-18), Netrin-1 (NTN-1), and sodium hydrogen exchanger isoform 3 (NHE3) on development and early diagnosis of AKI in newborns with perinatal asphyxia (PA).

METHODS

Forty-one newborns with a diagnosis of PA (15 with AKI and 26 without AKI) and 20 healthy matched controls were involved to the study. Urinary samples were obtained on postnatal days 1 and 4 for patients with PA and on postnatal day 1 for the control subjects. AKI was defined using a serum creatinine-based modification of the acute kidney injury network criteria.

RESULTS

The levels of NGAL, NTN-1, NHE3, and IL-18 on the first postnatal day urine samples were higher in patients compared to controls (p < 0.001, p <0.001, p  <0.02, p  <0.001, respectively). In patients with AKI, the levels of NGAL and IL-18 were higher when compared to patients without AKI (p = 0.002, p  <0.001, respectively). The levels of NTN-1 and NHE3 were similar in both groups. For the samples obtained on postnatal day 4, only NGAL levels were significantly higher in patients with AKI (p = 0.004) compared to those without AKI.

CONCLUSION

To our knowledge, this is the largest study, which evaluated the utility of urinary biomarkers in the diagnosis of AKI in newborns with PA. First day, urine NGAL and IL-18 levels have an important diagnostic power in such patients.

Novel biomarkers for early diagnosis of acute kidney injury after cardiac surgery in adults

Acute kidney injury after cardiac surgery with cardiopulmonary bypass is a common and serious complication and it is associated with increased morbidity and mortality. Diagnosis of acute kidney injury is based on the serum creatinine levels which rise several hours to days after the initial injury. Thus, novel biomarkers that will enable faster diagnosis are needed in clinical practice. There are numerous urine and serum proteins that indicate kidney injury and are under extensive research. Despite promising basic research results and assembled data, which indicate superiority of some biomarkers to creatinine, we are still awaiting clinical application.

Human Urine Proteomics: Analytical Techniques and Clinical Applications in Renal Diseases

Urine has been in the center of attention among scientists of clinical proteomics in the past decade, because it is valuable source of proteins and peptides with a relative stable composition and easy to collect in large and repeated quantities with a noninvasive procedure. In this review, we discuss technical aspects of urinary proteomics in detail, including sample preparation, proteomic technologies, and their advantage and disadvantages. Several recent experiments are presented which applied urinary proteome for biomarker discovery in renal diseases including diabetic nephropathy, immunoglobulin A (IgA) nephropathy, focal segmental glomerulosclerosis, lupus nephritis, membranous nephropathy, and acute kidney injury. In addition, several available databases in urinary proteomics are also briefly introduced.

Netrin-1 as a novel therapeutic target in cardiovascular disease: to activate or inhibit?

Netrins are a family of laminin-like proteins, which were initially identified for their role in embryonic axonal guidance. Over recent years, it has become apparent that netrin-1 may additionally be involved in the underlying pathology of several multisystem diseases, making it an attractive potential therapeutic target. It is involved in postnatal angiogenesis, particularly in the context of an ischaemic insult, although there are conflicting reports as to whether netrin-1 acts in a pro- or anti-angiogenic capacity. In atherosclerosis, opposing effects have similarly been reported on plaque progression, due to the ability of netrin-1 to inhibit both macrophage egress from and monocyte ingress into lesions. Netrin-1 has also been shown to exert a cardioprotective action in the context of ischaemia-reperfusion injury following myocardial infarction. Moreover, urinary netrin-1 levels rise in response to acute kidney injury and at a faster rate than traditional markers of renal impairment, highlighting a potential clinical role for netrin-1 as a biomarker of renal function. The increased urinary excretion of netrin-1 during kidney disease is paralleled by a down-regulation of its plasma levels, with potential implications at a systemic level. In summary, the role of netrin-1 in cardiovascular disease is an emerging area of research requiring further in-depth study to elucidate its mechanism of action and potential as a therapeutic target, especially in view of its seemingly contradictory actions in certain physiological pathways which serve to highlight its manifold and often opposite effects in numerous physiological and pathophysiological processes.

MicroRNA-150 deletion in mice protects kidney from myocardial infarction-induced acute kidney injury

Despite greater understanding of acute kidney injury (AKI) in animal models, many of the preclinical studies are not translatable. Most of the data were derived from a bilateral renal pedicle clamping model with warm ischemia. However, ischemic injury of the kidney in humans is distinctly different and does not involve clamping of renal vessel. Permanent ligation of the left anterior descending coronary artery model was used to test the role of microRNA (miR)-150 in AKI. Myocardial infarction in this model causes AKI which is similar to human cardiac bypass surgery. Moreover, the time course of serum creatinine and biomarker elevation were also similar to human ischemic injury. Deletion of miR-150 suppressed AKI which was associated with suppression of inflammation and interstitial cell apoptosis. Immunofluorescence staining with endothelial marker and marker of apoptosis suggested that dying cells are mostly endothelial cells with minimal epithelial cell apoptosis in this model. Interestingly, deletion of miR-150 also suppressed interstitial fibrosis. Consistent with protection, miR-150 deletion causes induction of its target gene insulin-like growth factor-1 receptor (IGF-1R) and overexpression of miR-150 in endothelial cells downregulated IGF-1R, suggesting miR-150 may mediate its detrimental effects through suppression of IGF-1R pathways.

Diagnosis of infection in critical care

Sepsis is the primary cause of death in the intensive care unit. The prevention of sepsis complications requires an early and accurate diagnosis as well as the appropriate mon itoring. A deep knowledge of the immunologic basis of sepsis is essential to better understand the scope of incorporating a new marker into clinical practice. Besides revising this theoretical aspect, the current available tools for bacterial iden tification have been briefly reviewed as well as a variety of new markers showing either well-recognized or potential usefulness for diagnosis and prognosis of infections in crit ically ill patients. Particular conditions such as community acquired pneumonia, pedi atric sepsis, or liver transplantation, among others, have been separately treated, since the optimal approaches and markers might be different in these special cases.

Netrin-1 and semaphorin 3A predict the development of acute kidney injury in liver transplant patients

Acute kidney injury (AKI) is a serious complication after liver transplantation. Currently there are no validated biomarkers available for early diagnosis of AKI. The current study was carried out to determine the usefulness of the recently identified biomarkers netrin-1 and semaphorin 3A in predicting AKI in liver transplant patients. A total of 63 patients’ samples were collected and analyzed. AKI was detected at 48 hours after liver transplantation using serum creatinine as a marker. In contrast, urine netrin-1 (897.8±112.4 pg/mg creatinine), semaphorin 3A (847.9±93.3 pg/mg creatinine) and NGAL (2172.2±378.1 ng/mg creatinine) levels were increased significantly and peaked at 2 hours after liver transplantation but were no longer significantly elevated at 6 hours after transplantation. The predictive power of netrin-1, as demonstrated by the area under the receiver-operating characteristic curve for diagnosis of AKI at 2, 6, and 24 hours after liver transplantation was 0.66, 0.57 and 0.59, respectively. The area under the curve for diagnosis of AKI was 0.63 and 0.65 for semaphorin 3A and NGAL at 2 hr respectively. Combined analysis of two or more biomarkers for simultaneous occurrence in urine did not improve the AUC for the prediction of AKI whereas the AUC was improved significantly (0.732) only when at least 1 of the 3 biomarkers in urine was positive for predicting AKI. Adjusting for BMI, all three biomarkers at 2 hours remained independent predictors of AKI with an odds ratio of 1.003 (95% confidence interval: 1.000 to 1.006; P = 0.0364). These studies demonstrate that semaphorin 3A and netrin-1 can be useful early diagnostic biomarkers of AKI after liver transplantation.

Urinary semaphorin 3A correlates with diabetic proteinuria and mediates diabetic nephropathy and associated inflammation in mice

Semaphorin 3A (sema3A) was recently identified as an early diagnostic biomarker of acute kidney injury. However, its role as a biomarker and/or mediator of chronic kidney disease (CKD) related to diabetic nephropathy is unknown. We examined the expression of sema3A in diabetic animal models and in humans and tested whether sema3A plays a pathogenic role in the development of diabetic nephropathy. The expression of sema3A was localized to podocytes and epithelial cells in distal tubules and collecting ducts in control animals, and its expression was increased following the induction of diabetes. Quantification of sema3A urinary excretion in three different diabetic mouse models showed that excretion was increased as early as 2 weeks after the induction of diabetes and increased over time, in conjunction with the development of nephropathy. Consistent with the mouse data, increased sema3A urinary excretion was detected in diabetic patients with albuminuria, particularly in those with macroalbuminuria. Genetic ablation of sema3A or pharmacological inhibition with a novel sema3A inhibitory peptide was protected against diabetes-induced albuminuria, kidney fibrosis, inflammation, oxidative stress, and renal dysfunction. We conclude that sema3A is both a biomarker and a mediator of diabetic kidney disease and could be a promising therapeutic target in diabetic nephropathy. Key messages Diabetes induced sema3A excretion in urine. Increased semaphorin 3A was associated with severity of albuminuria. Seme3A-mediated diabetes induced glomerulosclerosis. Peptide-based inhibition of semaphorin3A suppressed diabetic nephropathy.

Acute kidney injury in the neonate

Critically ill neonates are at risk for acute kidney injury (AKI). AKI has been associated with increased risk of morbidity and mortality in adult and pediatric patients, and increasing evidence suggests a similar association in the neonatal population. This article describes the current AKI definitions (including their limitations), work on novel biomarkers to define AKI, diagnosis and management strategies, long-term outcomes after AKI, and future directions for much-needed research in this important area.

Urinary netrin-1 and KIM-1 as early biomarkers for septic acute kidney injury

BACKGROUND

Acute kidney injury (AKI) during sepsis is associated with poor outcome. However, diagnosis of AKI with serum creatinine (SCr) level change is neither highly sensitive nor specific. Therefore, identification of novel biomarkers for early diagnosis of AKI is desirable.

AIMS

To evaluate the capacity of combining urinary netrin-1 and human kidney injury molecule type 1 (KIM-1) in the early diagnosis of septic AKI.

METHODS

We prospectively recruited 150 septic patients from Jun 2011 to Jun 2013 at Zhejiang Provincial People's Hospital, China. SCr, urinary netrin-1, and KIM-1 levels were recorded at 0, 1, 3, 6, 24, and 48 h of ICU admission and compared between AKI and non-AKI patients. In addition, we investigated the prognostic value of netrin-1 and KIM-1 between non-survivors and survivors in septic AKI patients.

RESULTS

SCr levels started to show elevation after 24 h of ICU admission. However, netrin-1 levels increased significantly as early as 1 h, peaked at 3-6 h and remained elevated up to 48 h of ICU admission in septic AKI patients. KIM-1 increased significantly by 6 h, peaked at 24 h and remained significantly elevated until 48 h of ICU admission. Furthermore, we observed significant higher urinary KIM-1 levels at 24 h and 48 h in non-survivors compared to survivors in AKI patients.

CONCLUSIONS

Our results suggest that both netrin-1 and KIM-1 are clinically useful as early biomarkers in the diagnosis of septic AKI. In addition, persistent elevation of urinary KIM-1 level may be associated with poor prognosis.

Age-related differences in kidney injury biomarkers induced by cisplatin

Acute kidney injury (AKI) occurs in a half of cisplatin (CDDP)-treated patients. Traditional biomarkers including blood urea nitrogen (BUN) and serum creatinine (SCr) are still used for detection of CDDP-induced AKI, but these biomarkers are not specific or sensitive. The aim of this study was to identify the specific and sensitive biomarkers against CDDP-induced renal injury between young (3-week-old) and old (20-week-old) rats. All animals were intraperitoneally injected once with CDDP (6 mg/kg). After 3 days, all animals were sacrificed and serum, urine, and kidney tissues were collected. Urinary and serum biomarkers as well as histological changes were measured. CDDP-induced proximal tubular damage was apparent from histopathological examination, being more severe in 3-week-old rats accompanied by increased number of TUNEL-positive apoptotic cells. This was associated with elevated urinary kidney injury molecule-1 (KIM-1), glutathione-S-transferase alpha (GST-α), vascular endothelial growth factor (VEGF), and tissue inhibitor of metalloproteinases-1 (TIMP-1). In contrast, the levels of neutrophil gelatinase-associated lipocalin (NGAL) and osteopontin were significantly increased in 20-week-old rats after CDDP treatment. These results indicate that the use of age-specific urinary biomarkers is necessary to diagnosis of CDDP-induced AKI. Especially, urinary KIM-1, GST-α, TIMP-1, and VEGF levels may help in the early diagnosis of young patients with CDDP-induced AKI.

Netrin-1, a urinary proximal tubular injury marker, is elevated early in the time course of human diabetes

BACKGROUND

Netrin-1 was recently identified as an early diagnostic biomarker of chronic kidney disease (CKD) in an experimental animal model. However, its usefulness for early diagnosis of CKD in humans is unknown. The current study evaluated whether netrin-1 is increased in urine from human diabetic patients.

METHODS

Spot urine samples from healthy volunteers, diabetes without microalbuminuria, diabetes with microalbuminuria and diabetes with macroalbuminuria were collected after receiving consent. Netrin-1 in urine was quantified by enzyme-linked immunosorbent assay and the data analyzed to determine whether urinary netrin-1 significantly correlates with disease progression.

RESULTS

Urinary netrin-1 levels were significantly increased in normoalbuminuric diabetic patients compared to healthy controls, and still further elevated in patients with microalbuminuria and overt nephropathy. Urinary netrin-1 was significantly associated with albuminuria and estimated glomerular filtration rate, independently of age and sex.

CONCLUSION

Netrin-1 is detectable in urine from diabetic patients and may serve as a useful early diagnostic biomarker predicting the development of CKD in diabetes.