Clinical use of biomarkers for toxicant-induced acute kidney injury

Efficacy of stem cell-based therapies for colistin-induced nephrotoxicity

The increase in infections with multidrug resistant bacteria has forced to return to the use of colistin, antibiotic with known nephrotoxicity. Mesenchymal stem cells (MSCs) are being extensively investigated for their potential in regenerative medicine. This study aimed to investigate the possible protective mechanisms of the MSCs against kidney injury induced by colistin. Forty adult female albino rats were randomly classified into 4 equal groups; the control group, the MSC-treated group (a single dose of 1 ×10⁶ /ml MSCs through the tail vein), the colistin-treated group (36 mg/kg/day colistin was given for 7 days), and the both colistin and MSC group (36 mg/kg/day colistin and 1 ×10⁶ /ml MSCs). Main outcome measures were histopathological alterations, kidney malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and immunohistological autophagy evaluation. MSC repressed the progression of colistin-induced kidney injury as evidenced by the improvement of histopathological alterations and the substantial increase MDA, and decrease SOD and CAT in serum levels. Moreover, MSC resulted in a profound reduction in oxidative stress as manifested by decreased MDA and increased SOD in serum. Notably, MSC suppressed colistin-induced autophagy; it reduced renal levels of Beclin-1, P62 and LC3A/B. Furthermore, MSC decreased renal levels of eNOS. Lastly, MSC efficiently decreased expression of the TUNEL positive cell number. MSC confers protection against colistin-induced kidney injury by alleviating oxidative stress, nitric oxide synthase besides modulating reducing autophagy and apoptosis.

Circulating heart failure biomarkers beyond natriuretic peptides: review from the Biomarker Study Group of the Heart Failure Association (HFA), European Society of Cardiology (ESC)

New biomarkers are being evaluated for their ability to advance the management of patients with heart failure. Despite a large pool of interesting candidate biomarkers, besides natriuretic peptides virtually none have succeeded in being applied into the clinical setting. In this review, we examine the most promising emerging candidates for clinical assessment and management of patients with heart failure. We discuss high-sensitivity cardiac troponins (Tn), procalcitonin, novel kidney markers, soluble suppression of tumorigenicity 2 (sST2), galectin-3, growth differentiation factor-15 (GDF-15), cluster of differentiation 146 (CD146), neprilysin, adrenomedullin (ADM), and also discuss proteomics and genetic-based risk scores. We focused on guidance and assistance with daily clinical care decision-making. For each biomarker, analytical considerations are discussed, as well as performance regarding diagnosis and prognosis. Furthermore, we discuss potential implementation in clinical algorithms and in ongoing clinical trials.

Nephroprotective Effect of Mesenchymal Stem Cell-Based Therapy of Kidney Disease Induced by Toxicants

BACKGROUND

Renal damage caused by drug toxicity is becoming increasingly common in the clinic. Preventing and treating kidney damage caused by drug toxicity are essential to maintain patient health and reduce the social and economic burden. In this study, we performed a meta-analysis to assess the nephroprotective effect of mesenchymal stem cells (MSCs) in the treatment of kidney disease induced by toxicants.

METHODS

The Cochrane Library, Embase, ISI Web of Science, and PubMed databases were searched up to December 31, 2019, to identify studies and extract data to assess the efficacy of MSCs treatment of kidney disease induced by toxicants using Cochrane Review Manager Version 5.3. A total of 27 studies were eligible and selected for this meta-analysis.

RESULTS

The results showed that a difference in serum creatinine levels between the MSC treatment group and control group was observed for 2, 4, 5, 6-8, 10-15, 28-30, and ≥42 days (2 days: WMD = -0.88, 95% CI: -1.34, -0.42, P = 0.0002; 4 days: WMD = -0.74, 95% CI: -0.95, -0.54, P < 0.00001; 5 days: WMD = -0.46, 95% CI: -0.67, -0.25, P < 0.0001; 6-8 days: WMD = -0.55, 95% CI: -0.84, -0.26, P = 0.0002; 10-15 days: WMD = -0.37, 95% CI: -0.53, -0.20, P < 0.0001; 28-30 days: WMD = -0.53, 95% CI: -1.04, -0.02, P = 0.04; ≥42 days: WMD = -0.22, 95% CI: -0.39, -0.06, P = 0.007). Furthermore, a difference in blood urea nitrogen levels between the MSC treatment group and control group was observed for 2-3, 4-5, 6-8, and ≥28 days. The results also indicate that MSC treatment alleviated inflammatory cells, necrotic tubules, regenerative tubules, and renal interstitial fibrosis in kidney disease induced by toxicants.

CONCLUSION

MSCs may be a promising therapeutic agent for kidney disease induced by toxicants.

Drug management in acute kidney disease - Report of the Acute Disease Quality Initiative XVI meeting

AIMS

To summarize and extend the main conclusions and recommendations relevant to drug management during acute kidney disease (AKD) as agreed at the 16^th Acute Disease Quality Initiative (ADQI) consensus conference.

METHODS

Using a modified Delphi method to achieve consensus, experts attending the 16^th ADQI consensus conference reviewed and appraised the existing literature on drug management during AKD and identified recommendations for clinical practice and future research. The group focussed on drugs with one of the following characteristics: (i) predominant renal excretion; (ii) nephrotoxicity; (iii) potential to alter glomerular function; and (iv) presence of metabolites that are modified in AKD and may affect other organs.

RESULTS

We recommend that medication reconciliation should occur at admission and discharge, at AKD diagnosis and change in AKD phase, and when the patient's condition changes. Strategies to avoid adverse drug reactions in AKD should seek to minimize adverse events from overdosing and nephrotoxicity and therapeutic failure from under-dosing or incorrect drug selection. Medication regimen assessment or introduction of medications during the AKD period should consider the nephrotoxic potential, altered renal and nonrenal elimination, the effects of toxic metabolites and drug interactions and altered pharmacodynamics in AKD. A dynamic monitoring plan including repeated serial assessment of clinical features, utilization of renal diagnostic tests and therapeutic drug monitoring should be used to guide medication regimen assessment.

CONCLUSIONS

Drug management during different phases of AKD requires an individualized approach and frequent re-assessment. More research is needed to avoid drug associated harm and therapeutic failure.

Dexamethasone Modifies Cystatin C-Based Diagnosis of Acute Kidney Injury During Cisplatin-Based Chemotherapy

BACKGROUND/AIMS

Plasma cystatin C (pCysC) may be superior to serum creatinine (sCr) as a surrogate of GFR. However, the performance of pCysC for diagnosing acute kidney injury (AKI) after cisplatin-based chemotherapy is potentially affected by accompanying corticosteroid anti-emetic therapy and hydration.

METHODS

In a prospective observational study pCysC, sCr, urinary kidney injury molecule-1 (KIM-1), and urinary clusterin were measured over 2 weeks in 27 patients given first-cycle chemotherapy. The same variables were measured over 2 weeks in Sprague-Dawley rats given a single intraperitoneal injection of dexamethasone, cisplatin, or both, and in controls.

RESULTS

In patients, pCysC increases were greater than sCr 41% vs. 16%, mean paired difference 25% (95% CI: 16-34%)], relative increases were ≥ 50% in 9 patients (35%) for pCysC compared with 2 (8%) for sCr (p = 0.04) and increases in sCr were accompanied by increased KIM-1 and clusterin excretion, but increases in pCysC alone were not. In rats, dexamethasone administration produced dose-dependent increases in pCysC (and augmented cisplatin-induced increases in pCysC), but did not augment histological injury, increases in sCr, or KIM-1 and clusterin excretion.

CONCLUSIONS

In the presence of dexamethasone, elevation of pCysC does not reliably diagnose AKI after cisplatin-based chemotherapy.

Effects of atorvastatin on biomarkers of acute kidney injury in amikacin recipients: A pilot, randomized, placebo-controlled, clinical trial

BACKGROUND

The most common clinical indication of aminoglycosides (AG) is the treatment of serious Gram-negative infections. The aim of this study was to evaluate plausible effects of atorvastatin on the biomarkers of acute kidney injury (AKI) in patients receiving amikacin.

MATERIALS AND METHODS

In this double-blinded randomized clinical trial, fifty patients (25 in each group) receiving amikacin (15 mg/kg/day) were randomly assigned to either atorvastatin (40 mg/day) or placebo (40 mg/day) groups for 7 days. Blood urea nitrogen (BUN), serum creatinine (SCr), and urinary neutrophil gelatinase-associated lipocalin (NGAL) levels were measured at days 0, 1, and 7 of amikacin treatment.

RESULTS

During the study period, 4 (8%) patients including two patients in each atorvastatin and placebo group experienced AKI. Urine NGAL/urine Cr did not change significantly between and within placebo and atorvastatin groups during the study period. Similarly, the mean changes in SCr, BUN, and urine NGAL/urine Cr values did not differ significantly between and within patients with and without AKI.

CONCLUSION

Our data suggested that the changing pattern of urine NGAL/urine Cr ratio did not differ significantly between the atorvastatin and placebo groups during the early phase of amikacin treatment.

Dynamic prediction of the need for renal replacement therapy in intensive care unit patients using a simple and robust model

We aimed at identifying a model that dynamically predicts future need for renal replacement therapy (RRT) in intensive care unit (ICU) patients and can easily be implemented for online monitoring at the bedside. 7290 interdisciplinary ICU admissions were investigated. Patients with <3 days of stay or RRT in the first 2 days were excluded. 1624 of the remaining 2625 patients had a normal serum creatinine at admission. Every second of these 1624 patients was used for model calibration whereas the other half and, in addition, the 1001 patients with elevated serum creatinine were exclusively used for validation. Discriminant analysis was used to determine and validate a combination of clinical parameters that predicts the need for RRT 72 h ahead. Based on the calibration sample, stepwise discriminant analysis selected the serum values of (1) current urea, (2) current lactate, (3) the ratio of current and admission serum creatinine, and (4) the mean urine output of the previous 24 h. In the validation datasets, the model reached areas under the receiver operating characteristic curve of 0.866 and 0.833 in patients with normal and elevated serum creatinine at admission, respectively. Moreover, the model's predictive value extended to at least 5 days prior to initiation of RRT and exceeded that of the RIFLE classification at all investigated prediction intervals. We identified a robust model that dynamically predicts the future need for RRT successfully. This tool may help improve timing of therapy and prognosis in ICU patients.

Biomarkers in Acute Heart Failure - Cardiac And Kidney

Natriuretic peptides (NP) are well-validated aids in the diagnosis of acute decompensated heart failure (ADHF). In acute presentations, both brain natriuretic peptide (BNP) and N-terminal of the prohormone brain natriuretic peptide (NT-proBNP) offer high sensitivity (>90 %) and negative predictive values (>95 %) for ruling out ADHF at thresholds of 100 and 300 pg/ml, respectively. Plasma NP rise with age. For added rule-in performance age-adjusted thresholds (450 pg/ml for under 50 years, 900 pg/ml for 50-75 years and 1,800 pg/ml for those >75 years) can be applied to NT-proBNP results. Test performance (specificity and accuracy but not sensitivity) is clearly reduced by renal dysfunction and atrial fibrillation. Obesity offsets the threshold downwards (to ~50 pg/ml for BNP), but overall discrimination is preserved. Reliable markers for impending acute kidney injury in ADHF constitute an unmet need, with candidates, such as kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin, failing to perform sufficiently well, and new possibilities, including the cell cycle markers insulin growth factor binding protein 7 and tissue inhibitor of metalloproteinases type 2, remain the subject of research.

Biomarkers of drug-induced acute kidney injury in the adult

INTRODUCTION

This article addresses general biomarkers of drug-induced acute kidney injury (AKI) and their application in development and progression of AKI in the adult. It also highlights some clinical benefits, but also uncertainties, of biomarker use.

AREAS COVERED

Drug-induced AKI is traditionally diagnosed by monitoring serum creatinine (SCr), blood urea nitrogen and albuminuria. The sensitivity of these measures is, however, limited to well-established AKI. Application of selected biomarkers for early diagnosis of drug-induced AKI may inform on progression of AKI and alert clinicians to adopt renoprotective strategies at the earliest times. Novel biomarkers, accepted for early detection of drug-induced AKI (kidney injury molecule-1, neutrophil gelatinase-associated lipocalin and N-acetyl-β-d-glucosaminidase), may be useful additions in panels of biomarkers. Clinical biomarkers of cell cycle arrest, tissue inhibitor of metalloproteinase-2 and insulin-like growth factor binding protein 7 show promise but need further validation in clinical trials.

EXPERT OPINION

Traditional parameters, such as SCr, provide some guidance for functional decline in drug-induced AKI but early, more sensitive, affordable, clinically acceptable, biomarkers of kidney dysfunction are needed. Basic biological understanding of AKI will improve with high-throughput methodologies such as proteomics and metabolomics, and this should lead to identification and usage of novel biomarkers. Ultimately, a combination of biomarkers indicating kidney dysfunction and damage is likely to be required.

Renal tubular damage may contribute more to acute hyperglycemia induced kidney injury in non-diabetic conscious rats

AIMS

Growing evidences suggest that acute hyperglycemia is strongly related to kidney injury. Our study aimed to investigate the effects of acute hyperglycemia on kidney glomerular and tubular impairment in non-diabetic conscious rats.

METHODS

Non-diabetic conscious rats were randomly subjected to 6h of saline (control group) or high glucose (acute hyperglycemia group) infusion. Blood glucose was maintained at 16.0-18.0 mmol/L in acute hyperglycemia group. Renal structure and function alterations, systemic/renal inflammation and oxidative stress markers were assessed, and apoptosis markers of renal inherent cells were evaluated.

RESULTS

Acute hyperglycemia caused significant injury to structure of glomerular filtration barrier, tubular epithelial cells and peritubular vascular endothelial cells. It increased urinary microalbumin (68.01 ± 27.09 μg/24h vs 33.81 ± 13.81 μg/24h , P=0.014), β2-microglobulin, Cystatin C, urinary and serous neutrophil gelatinase-associated lipocalin levels (P < 0.05). Acute hyperglycemia decreased megalin and cubilin expression, activated systemic and renal oxidative stress as well as inflammation and promoted renal inherent cell apoptosis.

CONCLUSIONS

Acute hyperglycemia causes significant injury to kidney function and structure. Compared with damages of glomerular filtration barrier, renal tubular injury may contribute more to acute hyperglycemia induced proteinuria. Activation of inflammation especially renal inflammation, oxidative stress and enhanced apoptosis may be the underlying mechanisms.

Role of biomarkers of nephrotoxic acute kidney injury in deliberate poisoning and envenomation in less developed countries

Acute kidney injury (AKI) has diverse causes and is associated with increased mortality and morbidity. In less developed countries (LDC), nephrotoxic AKI (ToxAKI) is common and mainly due to deliberate ingestion of nephrotoxic pesticides, toxic plants or to snake envenomation. ToxAKI shares some pathophysiological pathways with the much more intensively studied ischaemic AKI, but in contrast to ischaemic AKI, most victims are young, previously healthy adults. Diagnosis of AKI is currently based on a rise in serum creatinine. However this may delay diagnosis because of the kinetics of creatinine. Baseline creatinine values are also rarely available in LDC. Novel renal injury biomarkers offer a way forward because they usually increase more rapidly in AKI and are normally regarded as absent or very low in concentration, thereby reducing the need for a baseline estimate. This should increase sensitivity and speed of diagnosis. Specificity should also be increased for urine biomarkers since many originate from the renal tubular epithelium. Earlier diagnosis of ToxAKI should allow earlier initiation of appropriate therapy. However, translation of novel biomarkers of ToxAKI into clinical practice requires better understanding of non-renal factors in poisoning that alter biomarkers and the influence of dose of nephrotoxin on biomarker performance. Further issues are establishing LDC population-based normal ranges and assessing sampling and analytical parameters for low resource settings. The potential role of renal biomarkers in exploring ToxAKI aetiologies for chronic kidney disease of unknown origin (CKDu) is a high research priority in LDC. Therefore, developing more sensitive biomarkers for early diagnosis of nephrotoxicity is a critical step to making progress against AKI and CKDu in the developing world.

Kinetic Estimation of GFR Improves Prediction of Dialysis and Recovery after Kidney Transplantation

BACKGROUND

The early prediction of delayed graft function (DGF) would facilitate patient management after kidney transplantation.

METHODS

In a single-centre retrospective analysis, we investigated kinetic estimated GFR under non-steady-state conditions, KeGFR, in prediction of DGF. KeGFR(sCr) was calculated at 4h, 8h and 12h in 56 recipients of deceased donor kidneys from initial serum creatinine (sCr) concentrations, estimated creatinine production rate, volume of distribution, and the difference between consecutive sCr values. The utility of KeGFR(sCr) for DGF prediction was compared with, sCr, plasma cystatin C (pCysC), and KeGFR(pCysC) similarly derived from pCysC concentrations.

RESULTS

At 4h, the KeGFR(sCr) area under the receiver operator characteristic curve (AUC) for DGF prediction was 0.69 (95% CI: 0.56-0.83), while sCr was not useful (AUC 0.56, (CI: 0.41-0.72). Integrated discrimination improvement analysis showed that the KeGFR(sCr) improved a validated clinical prediction model at 4h, 8h, and 12h, increasing the AUC from 0.68 (0.52-0.83) to 0.88 (0.78-0.99) at 12h (p = 0.01). KeGFR(pCysC) also improved DGF prediction. In contrast, sCr provided no improvement at any time point.

CONCLUSIONS

Calculation of KeGFR from sCr facilitates early prediction of DGF within 4 hours of renal transplantation.

Clusterin in kidney transplantation: novel biomarkers versus serum creatinine for early prediction of delayed graft function

BACKGROUND AND OBJECTIVES

Current methods for rapid detection of delayed graft function (DGF) after kidney transplantation are unreliable. Urinary clusterin is a biomarker of kidney injury but its utility for prediction of graft dysfunction is unknown.

METHODS

In a single-center, prospective cohort study of renal transplant recipients (N=81), urinary clusterin was measured serially between 4 hr and 7 days after transplantation. The utility of clusterin for prediction of DGF (hemodialysis within 7 days of transplantation) was compared with urinary interleukin (IL)-18, neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1, serum creatinine, and clinical variables.

RESULTS

At 4 hr after reperfusion, anuria was highly specific, but of low sensitivity for detection of DGF. At 4 hr, receiver operating characteristic analysis suggested that urinary clusterin, IL-18, kidney injury molecule-1, and NGAL concentration were predictive of DGF. After adjusting for preoperative clinical variables and anuria, clusterin and IL-18 independently enhanced the clinical model for prediction of DGF. Kidney injury molecule-1 only modestly improved the prediction of DGF, whereas NGAL, serum creatinine, and the creatinine reduction ratio did not improve on the clinical model. At 12 hr, the creatinine reduction ratio independently predicted DGF.

CONCLUSION

Both urinary clusterin and IL-18 are useful biomarkers and may allow triaging of patients with DGF within 4 hr of transplantation. Relative performance of biomarkers for prediction of graft function is time-dependant. Early and frequent measurements of serum creatinine and calculation of the creatinine reduction ratio also predict DGF within 12 hr of reperfusion.

Biomarkers of calcineurin inhibitor nephrotoxicity in transplantation

Over 35 years of use has demonstrated the revolutionary therapeutic benefits of calcineurin inhibitors (CNI) in not only preventing transplant rejection, but also the renal and nonrenal toxicity of CNI. Acute reversible and insidious irreversible forms of CNI nephrotoxicity have been identified, with ischemia from an imbalance between vasoconstrictors and vasodilators playing an important role. The ongoing search to define toxicity pathways has been enriched by ‘Omics’ studies. Changes in proteins including those involved in activation of pro-inflammatory responses, oxidative stress, ER stress and the unfolded protein response have been identified, and these may serve as biomarkers of toxicity. However, the current standard of CNI toxicity, histology, lacks specificity, which creates challenges for biomarker validation. This review focuses on progress in nephrotoxic pathway identification of CNI and biomarker validation.

Drug-induced nephrotoxicity: clinical impact and preclinical in vitro models

The kidney is a major target for drug-induced toxicity. Drug-induced nephrotoxicity remains a major problem in the clinical setting, where the use of nephrotoxic drugs is often unavoidable. This leads frequently to acute kidney injury, and current problems are discussed. One strategy to avoid such problems would be the development of drugs with decreased nephrotoxic potential. However, the prediction of nephrotoxicity during preclinical drug development is difficult and nephrotoxicity is typically detected only late. Also, the nephrotoxic potential of newly approved drugs is often underestimated. Regulatory approved or validated in vitro models for the prediction of nephrotoxicity are currently not available. Here, we will review current approaches on the development of such models. This includes a discussion of three-dimensional and microfluidic models and recently developed stem cell based approaches. Most in vitro models have been tested with a limited number of compounds and are of unclear predictivity. However, some studies have tested larger numbers of compounds and the predictivity of the respective in vitro model had been determined. The results showed that high predictivity can be obtained by using primary or stem cell derived human renal cells in combination with appropriate end points.