Urine KIM-1 as a Potential Biomarker of Acute Renal Injury After Circulatory Collapse in Children

Modified EBP-bFGF targeting endogenous renal extracellular matrix protects against renal ischemia-reperfusion injury in rats

Acute kidney injury (AKI) is a life-threatening disease primarily caused by renal ischemia-reperfusion (I/R) injury, which can result in renal failure. Currently, growth factor therapy is considered a promising and effective approach for AKI treatment. Basic fibroblast growth factor (bFGF), an angiogenic factor with potent activity, efficiently stimulates angiogenesis and facilitates regeneration of renal tissue. However, the unrestricted diffusion of bFGF restricts its clinical application in AKI treatment. Therefore, developing a novel sustained released system for bFGF could enhance its potential in treating AKI. In this study, we genetically engineered a multifunctional recombinant protein by fusing bFGF with a specific peptide (EBP). EBP-bFGF effectively binds to the extracellular matrix in the injured kidney, enabling slow release of bFGF in AKI. Furthermore, following orthotopic injection into I/R rats' ischemic kidneys, EBP-bFGF exhibited stable retention within the tissue. Additionally, EBP-bFGF suppressed apoptosis of renal cells, reduced renal fibrosis, and facilitated recovery of renal function. These findings suggest that EBP-bFGF delivery system represents a promising strategy for treating AKI.

Pre-clinical evaluation of biomarkers for the early detection of nephrotoxicity following alpha-particle radioligand therapy

PURPOSE

Cancer treatment with alpha-emitter-based radioligand therapies (α-RLTs) demonstrates promising tumor responses. Radiolabeled peptides are filtered through glomeruli, followed by potential reabsorption of a fraction by proximal tubules, which may cause acute kidney injury (AKI) and chronic kidney disease (CKD). Because tubular cells are considered the primary site of radiopeptides' renal reabsorption and potential injury, the current use of kidney biomarkers of glomerular functional loss limits the evaluation of possible nephrotoxicity and its early detection. This study aimed to investigate whether urinary secretion of tubular injury biomarkers could be used as an additional non-invasive sensitive diagnostic tool to identify unrecognizable tubular damage and risk of long-term α-RLT nephrotoxicity.

METHODS

A bifunctional cyclic peptide, melanocortin 1 ligand (MC1L), labeled with [203Pb]Pb-MC1L, was used for [212Pb]Pb-MC1L biodistribution and absorbed dose measurements in CD-1 Elite mice. Mice were treated with [212Pb]Pb-MC1L in a dose-escalation study up to levels of radioactivity intended to induce kidney injury. The approach enabled prospective kidney functional and injury biomarker evaluation and late kidney histological analysis to validate these biomarkers.

RESULTS

Biodistribution analysis identified [212Pb]Pb-MC1L reabsorption in kidneys with a dose deposition of 2.8, 8.9, and 20 Gy for 0.9, 3.0, and 6.7 MBq injected [212Pb]Pb-MC1L doses, respectively. As expected, mice receiving 6.7 MBq had significant weight loss and CKD evidence based on serum creatinine, cystatin C, and kidney histological alterations 28 weeks after treatment. A dose-dependent urinary neutrophil gelatinase-associated lipocalin (NGAL, tubular injury biomarker) urinary excretion the day after [212Pb]Pb-MC1L treatment highly correlated with the severity of late tubulointerstitial injury and histological findings.

CONCLUSION

Urine NGAL secretion could be a potential early diagnostic tool to identify unrecognized tubular damage and predict long-term α-RLT-related nephrotoxicity.

Exploring the Utility of Urinary Creatinine Adjustment for KIM-1, NGAL, and Cystatin C for the Assessment of Kidney Function: Insights from the C-KidnEES Cohort

Normalization of urinary biomarkers of kidney injury is a common practice in clinical and research settings to account for variations in urine concentration, and urinary creatinine is often used as a reference. However, to date, there is no consensus on the adjustment of urinary biomarkers with creatinine, and both absolute and creatinine-adjusted biomarker levels are adopted for making interpretations of kidney health. Hence, the present study aimed to investigate the associations of urinary creatinine with three widely used kidney injury biomarkers, KIM-1, NGAL, and cystatin C, to validate the applicability of urinary creatinine as a reference for normalization. A cross-sectional study was performed with 2100 students, 10-18 years of age in the Children's Kidney Environmental Exposure Study (C-KidnEES) cohort established in Sri Lanka. As identified in linear regression analyses, normalization of urinary KIM-1, NGAL, and Cys-C to urinary creatinine did not result in significant under-adjustment or over-adjustment to the absolute urinary concentrations, giving no specific rationale for creatinine adjustment. Hence, absolute urinary concentrations of the above biomarkers can be adopted for the characterization of subclinical kidney injury in adolescents in community studies where early morning urine sampling is practiced. However, for spot urine samples, consideration of both absolute and creatinine-adjusted biomarker levels would be a better approach.

Pre-clinical Evaluation of Biomarkers for Early Detection of Nephrotoxicity Following Alpha-particle Radioligand Therapy

Purpose

Cancer treatment with alpha-emitter-based radioligand therapies (α-RLTs) demonstrates promising tumor responses. Radiolabeled peptides are filtered through glomeruli, followed by potential reabsorption of a fraction by proximal tubules, which may cause acute kidney injury (AKI) and chronic kidney disease (CKD). Because tubular cells are considered the primary site of radiopeptides' renal reabsorption and potential injury, the current use of kidney biomarkers of glomerular functional loss limits the evaluation of possible nephrotoxicity and its early detection. This study aimed to investigate whether urinary secretion of tubular injury biomarkers could be used as additional non-invasive sensitive diagnostic tool to identify unrecognizable tubular damage and risk of long-term α-RLTs nephrotoxicity.

Methods

A bifunctional cyclic peptide, melanocortin ligand-1(MC1L), labeled with [ 203 Pb]Pb-MC1L, was used for [ 212 Pb]Pb-MC1L biodistribution and absorbed dose measurements in CD-1 Elite mice. Mice were treated with [ 212 Pb]Pb-MC1L in a dose escalation study up to levels of radioactivity intended to induce kidney injury. The approach enabled prospective kidney functional and injury biomarker evaluation and late kidney histological analysis to validate these biomarkers.

Results

Biodistribution analysis identified [ 212 Pb]Pb-MC1L reabsorption in kidneys with a dose deposition of 2.8, 8.9, and 20 Gy for 0.9, 3.0, and 6.7 MBq injected [ 212 Pb]Pb-MC1L doses, respectively. As expected, mice receiving 6.7 MBq had significant weight loss and CKD evidence based on serum creatinine, cystatin C, and kidney histological alterations 28 weeks after treatment. A dose-dependent urinary Neutrophil gelatinase-associated lipocalin (NGAL, tubular injury biomarker) urinary excretion the day after [ 212 Pb]Pb-MC1L treatment highly correlated with the severity of late tubulointerstitial injury and histological findings.

Conclusion

urine NGAL secretion could be a potential early diagnostic tool to identify unrecognized tubular damage and predict long-term α-RLT-related nephrotoxicity.

Absence of significant association of trace elements in nails with urinary KIM-1 biomarker among residents of Addis Ababa in Upper Awash Basin, Ethiopia: a cross-sectional study

The Akaki River in the Upper Awash Basin, which flows through Addis Ababa, the capital city of Ethiopia, has been highly polluted by sewage from factories and residential areas. A population-based cross-sectional study was used to assess the association between trace elements and kidney injury from residents living in polluted areas downstream (Akaki-Kality) versus upstream (Gullele) in Sub-Cities of Addis Ababa. A total of 95 individuals (53 from Akaki-Kality and 42 from Gullele) were included in the study. Kidney injury molecule 1 (KIM-1), lead, arsenic, cadmium, cobalt, lead, manganese, zinc, iron, copper, chromium and nickel were evaluated in residents' urine and nail samples. A large proportion (74%) of the sample population contained KIM-1, including 81% residents in Akaki-Kality and 64% residents in Gullele. KIM-1 was, however, not significantly different (p = 0.05) between the two Sub-Cities, with median of 0.224 ng/mL in Akaki-Kality and 0.152 ng/mL in Gullele. Most of the analyzed elements, except Pb, As, Cd and Co, were found in all of the nail samples, with median (µg/g) in the range of 442‒714 Fe, 97.0‒246 Zn, 11.6‒24.1 Mn, 4.49‒5.85 Cu, 1.46‒1.66 Cr and 1.22‒1.41 Ni. The high incidence of KIM-1 indicates a potential for long term renal tubular damage among residents of the Sub-Cities. The concentrations of the elements in nails were, however, not significantly associated (p = 0.05) with the corresponding levels of KIM-1 in urine. Hence, the observed KIM-1 might be related to exposure to toxic substances or factors other than those included in this study.

Urinary NGAL, IGFBP-7, and TIMP-2: novel biomarkers to predict contrast medium-induced acute kidney injury in children

Background

Serum creatinine (SCr) is unreliable in detecting acute changes in kidney function. Early recognition of contrast-induced acute kidney injury (CI-AKI) can provide better opportunities for preventive interventions. Therefore, the purpose of this study is to examine the value of the combined detection of urinary neutrophil gelatinase-associated lipocalin (NGAL), insulin-like growth factor binding protein-7 (IGFBP-7), and tissue inhibitor of metalloproteinase-2 (TIMP-2) in the early diagnosis of children with CI-AKI.

Methods

A prospective, single-center clinical trial was performed and included 172 children aged 0–18 years. The dynamic changes of urinary NGAL, IGFBP-7, and TIMP-2 levels in children with intravascular injection of contrast medium were investigated to determine whether they can diagnose CI-AKI early.

Results

CI-AKI occurred in 20 of 137 enrolled patients, and the incidence was 14.59%. In the CI-AKI group, urinary levels of NGAL, IGFBP-7, TIMP-2, and [IGFBP-7]*[TIMP-2] were significantly increased 2 h after angiography and remained at high levels at 6 h. Using a cutoff value of 36.274 ng/mL, the specificity was 70.0%, and the sensitivity was 68.4% for the prediction of CI-AKI, which was excellent for urinary NGAL. When both urinary IGFBP-7 and TIMP-2 were used together, urinary [IGFBP-7]*[TIMP-2] at 0.417(ng/mL)²/1000 was regarded as the cutoff value. The specificity was 80.0%, and the sensitivity was 81.2%.

Conclusions

NGAL, IGFBP-7, and TIMP-2 concentrations in the urine of children after receiving injections of contrast medium increased faster than SCr and had good clinical value for the early diagnosis of CI-AKI in children. The combination of IGFBP-7 and TIMP-2 was better than either analyte alone.

miR-181c, a potential mediator for acute kidney injury in a burn rat model with following sepsis

BACKGROUND

The miRNA profile is changed after burn or sepsis and is involved in regulating inflammatory reactions. However, the function and molecular mechanism of miRNAs in regulating burn sepsis-induced acute kidney injury (AKI) are still unclear.

METHODS

In this study, animal and cell sepsis models were established after burned rats were injected with lipopolysaccharide (LPS) or NRK-52E cells treated with LPS, respectively. Cytokine expression, inflammatory cell infiltration, serum creatinine (Scr) and kidney injury molecule-1 (KIM-1) levels were analysed after the indicated treatments.

RESULTS

Burn sepsis increased the expression of inflammatory factors (TNF-α and IL-1β) and chemokines (MIP-1α, MIP-2 and MCP-1). Moreover, burn sepsis promoted macrophage and neutrophil infiltration into the kidney and upregulated the levels of Scr and KIM-1 in the kidney and urine. Ectopic expression of miR-181c significantly reduced LPS-induced TLR4 protein expression, suppressed KIM-1 mRNA levels and subsequently inhibited the activation of inflammatory genes (TNF-α and IL-1β) and chemokine genes (MIP-1α, MIP-2 and MCP-1).

CONCLUSIONS

Our results demonstrated that miR-181c could suppress TLR4 expression, reduce inflammatory factor and chemokine secretion, mitigate inflammatory cell infiltration into the kidney and downregulate KIM-1 expression, which might ultimately attenuate burn sepsis-induced AKI.

Advances in the study of subclinical AKI biomarkers

Acute kidney injury (AKI) is a prevalent and serious illness in all clinical departments, with a high morbidity and death rate, particularly in intensive care units, where prevention and treatment are crucial. As a result, active prevention, early detection, and timely intervention for acute kidney injury are critical. The current diagnostic criteria for acute kidney injury are an increase in serum creatinine concentration and/or a decrease in urine output, although creatinine and urine output merely reflect changes in kidney function, and AKI suggests injury or damage, but not necessarily dysfunction. The human kidney plays a crucial functional reserve role, and dysfunction is only visible when more than half of the renal mass is impaired. Tubular damage markers can be used to detect AKI before filtration function is lost, and new biomarkers have shown a new subset of AKI patients known as “subclinical AKI.” Furthermore, creatinine and urine volume are only marginally effective for detecting subclinical AKI. As a result, the search for new biomarkers not only identifies deterioration of renal function but also allows for the early detection of structural kidney damage. Several biomarkers have been identified and validated. This study discusses some of the most promising novel biomarkers of AKI, including CysC, NGAL, KIM-1, lL-18, L-FABP, IGFBP7, TIMP-2, Clusterin, and Penkid. We examine their performance in the diagnosis of subclinical AKI, limitations, and future clinical practice directions.

uNGAL Predictive Value for Serum Creatinine Decrease in Critically Ill Children

Acute kidney injury (AKI) occurs frequently in critically ill children, having an incidence of up to 26.9% and is associated with high morbidity and mortality in pediatric intensive care units (PICU). Currently, the decrease in the glomerular filtration rate is calculated using the serum creatinine levels. Nevertheless, there may be a 48 h delay between the renal injury and measurable increase in creatinine. Urinary neutrophil gelatinase-associated lipocalin (uNGAL) has been validated in relation to cardiopulmonary bypass in children, being able to detect AKI before the functional change proven by the rise in serum creatinine. Our aim was to study the utility of using uNGAL in the management of critical pediatric patients admitted to our hospital in a six month period, more specifically, its capacity to predict AKI development, alone and in the association with the renal angina index (RAI). Twenty-eight critically ill children aged from 1 day to 15 years have been included. We found that an increase in uNGAL in day 1 of admission in the PICU was significantly correlated with a decrease in creatinine clearance but not anymore in day 3. However, in our sample uNGAL did not show a significant predictability for AKI development nor the supplementary incorporation of RAI into the prediction model. Therefore, apart from cardiac surgery, the efficacy and utility or uNGAL in the management of critically ill children is still questionable. For the best prediction, we will need to incorporate not only the RAI or other PICU scores, but other biomarkers such as KIM-1, urinary cystatin, and IL 18 in larger samples.

Value of urine IL-8, NGAL and KIM-1 for the early diagnosis of acute kidney injury in patients with ureteroscopic lithotripsy related urosepsis

PURPOSE

To investigate the clinical value of urine interleukin-18 (IL-8), neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) for the early diagnosis of acute kidney injury (AKI) in patients with ureteroscopic lithotripsy (URL) related urosepsis.

METHODS

A retrospective study was carried out in 157 patients with urosepsis after URL. The patients were divided into AKI group and non-AKI group according to the Kidigo guideline and urine IL-8, NGAL and KIM-1 levels were detected by enzyme-linked immunosorbent assay at 0, 4, 12, 24 and 48 h after the surgery. Receiver operating characteristic curve (ROC) was used to evaluate the diagnostic value of these three biomarkers for postoperative AKI.

RESULTS

The level of urine IL-8, NGAL and KIM-1 in AKI group was significantly higher than that in non-AKI group at 4, 12, 24 and 48 h (p < 0.01). The ROC analysis showed the combined detection of urine IL-8, NGAL and KIM-1 at 12 h had a larger area under curve (AUC) than a single marker (0.997, 95% CI: 0.991-0.998), and the sensitivity and specificity were 98.2% and 96.7%, respectively. Pearson correlation analysis showed that the levels of urine NGAL at 4, 12, 24 and 48 h in AKI patients were positively correlated with the levels of urine KIM-1 and IL-18 (p < 0.01).

CONCLUSION

AKI could be quickly recognized by the elevated level of urine IL-8, NGAL and KIM-1 in patients with URL-related urosepsis. Combined detection of the three urine biomarkers at 12 h after surgery had a better diagnostic performance, which may be an important reference for the early diagnosis of AKI.

Effect of a 3% gelatin solution on urinary KIM-1 levels in patients after thyroidectomy: a preliminary randomized controlled trial

Optimal fluid therapy significantly affects the maintenance of proper tissue perfusion and, consequently, kidney function. An adverse effect of colloids on kidney function is related to the incidence of postoperative kidney failure. The study aimed to assess the effect of a 3% gelatin solution on kidney function based on the urinary kidney injury molecule-1 (uKIM-1) level. This study used a parallel design and enrolled 64 adult patients with a mean age of 52.5 ± 13.1 years, all of whom underwent a thyroidectomy procedure under general anesthesia. Patients were randomly assigned to three comparison groups, each receiving a different dose of 3% gelatin solution during the thyroidectomy procedure. The patients from study groups A (n = 21) and B (n = 21) received a 3% gelatin solution at a dose of 30 ml/kg and 15 ml/kg body weight, respectively, during the first hour of the procedure. The patients from the control group C (n = 22) received an isotonic multi-electrolyte solution. Serum creatinine levels were determined, and urine samples were collected to determine levels of uKIM-1 before, 2 h, and 24 h after surgery. The patients' demographic data, type and volume of fluid and hemodynamic status during the surgery were collected from relevant anesthesia protocols and were included in the study data. There were no statistically significant changes between groups in hemodynamic parameters such as systolic and diastolic blood pressure, heart rate, and oxygen saturation values. A statistically significant increase in uKIM-1 level was noted in patients receiving the 3% gelatin solution regardless of the dose. A statistically significant difference in uKIM-1 level was observed between groups A, B, and C measured 24 h after surgery, with the highest uKIM-1 level in group A. Measurement of uKIM-1 level could be an early and sensitive biomarker of kidney injury. Kidney toxicity of a 3% gelatin solution, evaluated based on the level of uKIM-1 in urine, correlates with transfused fluid volume. This study was retrospectively registered in the ISRCTN clinical trials registry (ISRCTN73266049, 08/04/2021: https://www.isrctn.com/ISRCTN73266049 ).

Sepsis-Pathophysiology and Therapeutic Concepts

Sepsis is a life-threatening condition and a global disease burden. Today, the heterogeneous syndrome is defined as severe organ dysfunction caused by a dysregulated host response to infection, with renewed emphasis on immune pathophysiology. Despite all efforts of experimental and clinical research during the last three decades, the ability to positively influence course and outcome of the syndrome remains limited. Evidence-based therapy still consists of basic causal and supportive measures, while adjuvant interventions such as blood purification or targeted immunotherapy largely remain without proof of effectiveness so far. With this review, we aim to provide an overview of sepsis immune pathophysiology, to update the choice of therapeutic approaches targeting different immunological mechanisms in the course of sepsis and septic shock, and to call for a paradigm shift from the pathogen to the host response as a potentially more promising angle.

Curcumin plays a protective role against septic acute kidney injury by regulating the TLR9 signaling pathway

Background

This study aims to evaluate the inhibitory effect of curcumin (Cur) on the progression of septic acute kidney injury (SAKI), in order to improve the survival rate in this patient population.

Methods

Acute kidney injury (AKI) was induced by cecal ligation perforation (CLP) in Sprague-Dawley (SD) rats. Using this AKI animal model, the survival rate of the rats was evaluated at different time points after Cur treatment to explore whether Cur can improve survival in an animal model of AKI. The expression levels of inflammatory factors (NF-κB, TNF-α, and IL-10), organ injury markers [urea nitrogen (UN), creatinine (Cr), alanine aminotransferase (ALT), aspartate aminotransferase (AST), amylase, creatine kinase (CK), and lactate dehydrogenase (LDH)], and disease progression markers [neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and cystatin-C (CysC)] were determined using an enzyme-linked immunosorbent assay (ELISA).

Results

The serum levels of UN, Cr, NF-κB, ALT, AST, amylase, CK, LDH, inflammatory factors TNF-α and IL-10, and markers of early diagnosis of SAKI (NGAL, CysC, KIM-1) were significantly lower in the curcumin group than those in the placebo group (P<0.05). In addition, serum levels of TLR9 and its downstream molecules MyD88, IRF5, and IRF7 in the curcumin group were significantly lower than those in the placebo group (P<0.05). The application of TLR9-specific inhibitors to experimental rats led to similar results as those obtained in the curcumin group, whose detection indexes were significantly lower than those in the placebo treatment group (P<0.05).

Conclusions

Given the excellent performance of Cur in anti-tumor, anti-oxidation, anti-inflammatory, and other clinical trials, it is very likely to be further developed as a potential drug for the clinical treatment of AKI.

SGLT2 inhibitor empagliflozin monotherapy alleviates renal oxidative stress in albino Wistar diabetic rats after myocardial infarction induction

Acute kidney injury (AKI) is a sudden insult of the kidney that happens within a short period of time, which is associated with poor prognosis in diabetic patients with myocardial infarction (MI). Subclinical AKI is a condition in which tubular damage biomarkers [Neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1(KIM-1)] are positive even in the absence of elevated serum creatinine. Recent studies reported that SGLT-2 inhibitors could protect against subclinical AKI in diabetic patients by elevating the level of β-Hydroxybutyric acid (βOHB). This study aims to examine the reno-protective potential of empagliflozin (EMPA) against MI associated AKI in diabetic rats. Eighty Albino Wistar rats were divided into: (1) nondiabetic sham group (CS), (2) nondiabetic + myocardial infarction group (CM), (3) diabetic + myocardial infarction group (DM) and (4) diabetic + myocardial infarction + empagliflozin group (DME). At the end of the experiment, blood samples and kidneys were collected for biochemical analysis, histopathological, and immunohistochemical studies. After induction of myocardial infarction, there was a significant decrease in serum creatinine and NGAL levels in DME. After EMPA administration, mesangial matrix index and glomerular area were lowered in DME if compared to DM group. As a marker for tubular injury, we used anti-NGAL and anti-KIM-1 immunohistochemistry. Strong positive reaction was noticed in DM group if compared to DME group which showed weak positive reaction. Levels of renal mRNAs [NGAL; KIM-1; Nox-2,4; TLR-2,4; MyD88; TNF- α and IL-1 β, 18] in DME group were reduced significantly compared to DM group. In conclusion, empagliflozin can protect against subclinical acute kidney injury in diabetic albino Wistar rats after myocardial infarction induction, which could improve the clinical outcome of SGLT-2 inhibitors in diabetic patients.

Acute Kidney Injury in Pediatric Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a common complication of type 1 and 2 diabetes and often presents during adolescence and young adulthood. Given the growing incidence of both type 1 and type 2 diabetes in children and adolescents, DKD represents a significant public health problem. Acute kidney injury (AKI) in youth with diabetes is strongly associated with risk of DKD development. This review will summarize the epidemiology and pathophysiology of AKI in children with diabetes, the relationship between AKI and DKD, and the potential therapeutic interventions. Finally, we will appraise the impact of the recent COVID-19 infection pandemic on AKI in children with diabetes.

Role of urinary NGAL and KIM-1 as biomarkers of early kidney injury in obese prepubertal children

Objectives Childhood obesity is an important cause of end-stage renal disease. To date, available markers do not characterize kidney changes, especially in the early stages. kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) are already detected before the onset of proteinuria or alterations of glomerular filtration rate and thus might represent biomarkers that directly reflect kidney injury. Methods We characterize kidney injury in a group of 40 obese-prepubertal children compared to 29-healthy age- and gender matched-peers. Anthropometric measurements and body composition were determined. Fasting blood samples were collected for measurement of insulin, glucose, lipid profile, transaminases, cystatin C and creatinine. Urine samples were collected to assess urinary NGAL, KIM-1 and urinary isoprostanes. Kidney length was measured with ultrasound evaluation. Differences between the two groups were evaluated by Mann-Whitney U test, and Spearman correlation analysis was used to explore relationship between variables. Results Triglycerides, alanine transaminase (ALT), glucose, insulin, homeostasis model assessment insulin resistance, triglycerides/high-density lipoprotein (HDL)-cholesterol ratio and cystatin C values were significantly higher in obese children than normal weight peers. Creatinine values were normal and similar between the two groups, while isoprostanes were higher in obese. Obese children had larger kidney sizes, indicating organ hypertrophy. NGAL and KIM-1 were increased in obese children compared to controls. A significant association between NGAL and KIM-1 with adiposity indices, insulin status and markers of oxidative stress postulated a possible effect of obesity in inducing kidney abnormalities. KIM-1 and NGAL are directly related respectively to cystatin C and isoprostanes, supporting the ability of these biomarkers in reflecting early kidney damages in obese subjects. Conclusions These findings suggest that obese subjects exhibit a certain degree of renal damage before kidney function loss.

Novel biomarkers of acute kidney injury in children: an update on recent findings

PURPOSE OF REVIEW

The clinical diagnosis of acute kidney injury (AKI) relies largely on changes in serum creatinine; a delayed biomarker. Research in children has been focused on developing novel AKI biomarkers, which can improve the prediction, early detection and diagnosis of kidney injury, as well as our understanding of AKI pathophysiology. In this review, we describe recently published studies on urine or blood biomarkers of AKI. The mechanistic relevance of neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1, interleukin (IL)-18, liver-type fatty acid binding protein, tissue inhibitor of metalloproteinase (TIMP)-2/insulin-like growth factor-binding protein (IGFBP)-7, uromodulin, as well as other inflammatory biomarkers are discussed in the context of AKI pathophysiology, as well as their performance predicting or diagnosing AKI.

RECENT FINDINGS

Biomarkers of tubular injury, cell cycle arrest and inflammation are presented in this review. NGAL continues to be the most frequently studied biomarker and continues to have good performance in a variety of clinical settings, most notably after cardiopulmonary bypass. We also found promising results with less studied biomarkers for the prediction of AKI in children, including TIMP2, IGFBP7, uromodulin, tumor necrosis factor-α and IL-8.

SUMMARY

Identifying new AKI biomarkers is a priority in pediatric nephrology research because of the morbidity associated with AKI, as well as the lack of therapies for AKI. Recent research suggests that novel AKI biomarkers have the potential to predict the development of AKI and diagnose AKI earlier than changes in serum creatinine. The diverse causes of AKI, the different settings where patients develop AKI and the changing biomarker reference ranges throughout childhood remain challenges in biomarker development.