Loss of Dact2 alleviates cisplatin-induced nephrotoxicity through regulation of the Igfl-MAPK pathway axis

Wnt signaling is a principal pathway regulating the essential activities of cell proliferation. Here, we investigated the effect of Wnt/β-catenin signaling on in vivo drug-induced renal injury through the deletion of Dact2, a Wnt antagonist, and deciphered the underlying mechanism. Wild-type (WT) and Dact2 knockout (KO) mice were administered a single intraperitoneal injection of cisplatin to induce renal injury. The injury was alleviated in Dact2 KO mice, which showed lower levels of blood urea nitrogen and creatinine. RNA sequencing revealed 194 differentially expressed genes (DEGs) between WT and Dact2 KO mouse kidney before cisplatin treatment. Among them, higher levels of Igf1, one of the Wnt target genes responsible for "Positive regulation of cell proliferation" in KO mice, were confirmed along with the induction of Ki67 expression. In RNA-seq analysis comparing WT and Dact2 KO mice after cisplatin treatment, genes related to "Apoptosis" and "Activation of mitogen-activated protein kinase (MAPK) activity" were among the downregulated DEGs in KO mice. These results were corroborated in western blotting of proteins related to apoptosis and proapoptotic MAPK pathway; the expression of which was found to be lower in cisplatin-treated KO mice. Importantly, β-catenin was found to directly bind to and regulate the transcription of Igf1, leading to the alleviation of cisplatin-induced cytotoxicity by the Wnt agonist, CHIR-99021. In addition, Igf1 knockdown accelerated cisplatin-induced cytotoxicity, accompanied by the MAPK upregulation. Our findings suggest that Dact2 knockout could protect cisplatin-induced nephrotoxicity by inhibiting apoptosis, possibly through the regulation of the Igf1-MAPK axis associated with Wnt/β-catenin signaling.

Contemporary Biomarkers for Renal Transplantation: A Narrative Overview

Renal transplantation (RT) is the preferred treatment for end-stage renal disease. However, clinical challenges persist, i.e., early detection of graft dysfunction, timely identification of rejection episodes, personalization of immunosuppressive therapy, and prediction of long-term graft survival. Biomarkers have emerged as valuable tools to address these challenges and revolutionize RT patient care. Our review synthesizes the existing scientific literature to highlight promising biomarkers, their biological characteristics, and their potential roles in enhancing clinical decision-making and patient outcomes. Emerging non-invasive biomarkers seemingly provide valuable insights into the immunopathology of nephron injury and allograft rejection. Moreover, we analyzed biomarkers with intra-nephron specificities, i.e., glomerular vs. tubular (proximal vs. distal), which can localize an injury in different nephron areas. Additionally, this paper provides a comprehensive analysis of the potential clinical applications of biomarkers in the prediction, detection, differential diagnosis and assessment of post-RT non-surgical allograft complications. Lastly, we focus on the pursuit of immune tolerance biomarkers, which aims to reclassify transplant recipients based on immune risk thresholds, guide personalized immunosuppression strategies, and ultimately identify patients for whom immunosuppression may safely be reduced. Further research, validation, standardization, and prospective studies are necessary to fully harness the clinical utility of RT biomarkers and guide the development of targeted therapies.

Expression of ER stress markers (GRP78 and PERK) in experimental nephrotoxicity induced by cisplatin and gentamicin: roles of inflammatory response and oxidative stress

This study aimed to establish the relationship between two endoplasmic reticulum (ER) stress proteins, glucose-regulated protein 78 (GRP78/BiP) and PKR-like endoplasmic reticulum kinase (PERK), and oxidative stress markers in cisplatin (CIS)-induced and gentamicin (GEN)-induced nephrotoxicity.The study consisted of five groups: control (saline solution only), CIS D2 (2.5 mg/kg for 2 days), CIS D7 (2.5 mg/kg for 7 days), GEN D2 (160 mg/kg for 2 days), and GEN D7 (160 mg/kg for 7 days). All rats were sacrificed 24 h after the last injection for standard clinical chemistry, and ultrastructural and histological evaluation of the kidney.CIS and GEN increased blood urea nitrogen (BUN) and serum creatinine (Cr) levels, as well as total oxidant status (TOS), while decreasing total antioxidant status (TAS) level in CIS D7 and GEN D7 groups. Histopathological and ultrastructural findings were also consistent with renal tubular damage. In addition, expression of markers of renal inflammation (tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β)) and ER stress markers (GRP78 and PERK) was significantly increased in the kidney tissue of rats treated with CIS and GEN for 7 days.These findings suggest that CIS and GEN administration for 7 days aggravates nephrotoxicity through the enhancement of oxidative stress, inflammation, and ER stress-related markers. As a result, the recommended course of action is to utilize CIS and GEN as an immediate but brief induction therapy, stopping after 3 days and switching to other drugs instead.

Urine stabilization and normalization strategies favor unbiased analysis of urinary EV content

Urine features an ideal source of non-invasive diagnostic markers. Some intrinsic and methodological issues still pose barriers to its full potential as liquid biopsy substrate. Unlike blood, urine concentration varies with nutrition, hydration and environmental factors. Urine is enriched with EVs from urinary-genital tract, while its conservation, purification and normalization can introduce bias in analysis of EV subsets in inter-and intra-individual comparisons. The present study evaluated the methods that decrease such biases such as appropriate and feasible urine storage, optimal single-step EV purification method for recovery of proteins and RNAs from small urine volumes and a normalization method for quantitative analysis of urine EV RNAs. Ultracentrifugation, chemical precipitation and immuno-affinity were used to isolate EVs from healthy donors' urine that was stored frozen or at room temperature for up to 6 months. Multiple urine biochemical and EV parameters, including particle count and protein content, were compared across urine samples. To this purpose nanoparticle tracking analysis (NTA) and protein assessment by BCA, ELISA and WB assays were performed. These measurements were correlated with relative abundances of selected EV mRNAs and miRNAs assessed by RT-PCR and ranked for the ability to reflect and correct for EV content variations in longitudinal urine samples. All purification methods enabled recovery and downstream analysis of EVs from as few as 1 ml of urine. Our findings highlight long term stability of EV RNAs upon urine storage at RT as well as excellent correlation of EV content in urine with some routinely measured biochemical features, such as total urine protein and albumin, but not creatinine most conventionally used for urine normalization. Comparative evaluation of mRNA and miRNAs in EV isolates revealed specific RNAs, in particular RNY4 and small miRNA panel, levels of which well reflected the inter-sample EV variation and therefore useful as possible post-analytical normalizers of EV RNA content. We describe some realistic urine processing and normalization solutions for unbiased readout of EV biomarker studies and routine clinical sampling and diagnostics providing the input for design of larger validation studies employing urine EVs as biomarkers for particular conditions and diseases.

Research-Relevant Clinical Pathology Resources: Emphasis on Mice, Rats, Rabbits, Dogs, Minipigs, and Non-Human Primates

Clinical pathology testing for investigative or biomedical research and for preclinical toxicity and safety assessment in laboratory animals is a distinct specialty requiring an understanding of species specific and other influential variables on results and interpretation. This review of clinical pathology principles and testing recommendations in laboratory animal species aims to provide a useful resource for researchers, veterinary specialists, toxicologists, and clinical or anatomic pathologists.

Cisplatin Mouse Models: Treatment, Toxicity and Translatability

Cisplatin is one of the most widely used chemotherapeutic drugs in the treatment of a wide range of pediatric and adult malignances. However, it has various side effects which limit its use. Cisplatin mouse models are widely used in studies investigating cisplatin therapeutic and toxic effects. However, despite numerous promising results, no significant improvement in treatment outcome has been achieved in humans. There are many drawbacks in the currently used cisplatin protocols in mice. In the paper, the most characterized cisplatin protocols are summarized together with weaknesses that need to be improved in future studies, including hydration and supportive care. As demonstrated, mice respond to cisplatin treatment in similar ways to humans. The paper thus aims to illustrate the complexity of cisplatin side effects (nephrotoxicity, gastrointestinal toxicity, neurotoxicity, ototoxicity and myelotoxicity) and the interconnectedness and interdependence of pathomechanisms among tissues and organs in a dose- and time-dependent manner. The paper offers knowledge that can help design future studies more efficiently and interpret study outcomes more critically. If we want to understand molecular mechanisms and find therapeutic agents that would have a potential benefit in clinics, we need to change our approach and start to treat animals as patients and not as tools.

MiR-3168, miR-6125, and miR-4718 as potential predictors of cisplatin-induced nephrotoxicity in patients with head and neck cancer

Background

No biomarker is available for identifying cancer patients at risk of developing nephrotoxicity when treated with cisplatin.

Methods

We performed microRNA (miRNA) sequencing using plasma collected 5 days after cisplatin treatment (D5) from twelve patients with head and neck cancer with and without nephrotoxicity (grade ≥ 2 increased serum creatinine). The most differentially expressed miRNAs between the two groups were selected for quantification at baseline and D5 in a larger cohort of patients. The association between miRNAs and nephrotoxicity was evaluated by calculating the odds ratio (OR) from univariate logistic regression. Receiver operating characteristic curves (ROC) were used to estimate the area under the curve (AUC), sensitivity, and specificity.

Results

MiR-3168 (p = 1.98 × 10^− 8), miR-4718 (p = 4.24 × 10^− 5), and miR-6125 (p = 6.60 × 10^− 5) were the most differentially expressed miRNAs and were further quantified in 43, 48, and 53 patients, respectively. The baseline expression of miR-3168 (p = 0.0456, OR = 1.03, 95% CI: 1.00–1.06) and miR-4718 (p = 0.0388, OR = 1.56, 95% CI: 1.03–2.46) were associated with an increased risk of nephrotoxicity, whereas miR-6125 showed a trend (p = 0.0618, OR = 1.73, 95% CI: 0.98–3.29). MiR-4718 showed the highest AUC (0.77, 95% CI: 0.61–0.93) with sensitivity of 66.76 and specificity of 79.49.

Conclusions

We have provided evidence of baseline plasmatic expression of miR-3168, miR-6125, and miR-4718 as potential predictors of cisplatin-induced nephrotoxicity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08317-2.

Comparisons of segment-specific toxicity of platinum-based agents and cadmium using S1, S2, and S3 cells derived from mouse kidney proximal tubules

Renal toxicants such as cisplatin and cadmium cause segment-specific damages in kidney proximal tubules. Recently, we established an in vitro experimental system for evaluating segment-specific toxicity and transport of chemicals using immortalized S1, S2, and S3 cells derived from the S1, S2, and S3 regions of mouse kidney proximal tubules. In the present study, we examined the toxicity and accumulation of cisplatin, carboplatin, oxaliplatin, and cadmium in S1, S2, and S3 cells. We found that not only cisplatin but also carboplatin and oxaliplatin exhibited higher lethal toxicity in S3 cells than in S1 and S2 cells. At sublethal doses, cisplatin showed delayed induction of Kim-1 and clusterin on days 3 and 6, which may reflect the latent renal toxicity of cisplatin in vivo. The high sensitivities of S3 cells to the platinum-based agents were not due to the high accumulation of Pt in S3 cells. Exposure to cadmium resulted in similar toxicity among these cells, suggesting that S3 cells were not sensitive to any renal toxicants. Thus, the utilization of S1, S2, and S3 cells may provide a useful tool for the in vitro evaluation of the proximal tubule segment-specific toxicity of chemicals.

Spatial evaluation of long-term metabolic changes induced by cisplatin nephrotoxicity

Cisplatin is a widely used chemotherapeutic agent. However, it is causing nephrotoxic side effects including a reduced glomerular filtration rate and acute kidney injury. Although kidneys can recover to an extent from the treatment, long-term damage is possible. While a lot of research is focusing on short-term effects, little is known about adverse metabolic effects in the process of recovery. In this study, male Han Wistar rats were dosed with a single intraperitoneal injection of 3 mg/kg cisplatin. Urine and kidney samples were harvested 3, 8 and 26 days after administration. Tubular injury was demonstrated through urinary biomarkers. Complementing this, mass spectrometry imaging gives insight on molecular alterations on a spatial level, thus making it well suited to analyze short- and long-term disturbances. Various metabolic pathways seem to be affected, as changes in a wide range of metabolites were observed between treated and control animals. Besides previously reported early changes in kidney metabolism, unprecedented long-term effects were detected including deviation in nucleotides, antioxidants, and phospholipids.

Predicting the Need for a Tier II Ototoxicity Study From Early Renal Function Data

History has established that many drugs, such as the antibiotics, chemotherapies, and loop diuretics, are capable of inducing both nephrotoxicity and ototoxicity. The exact mechanisms by which cellular damage occurs remain to be fully elucidated. Monitoring the indices of renal function conducted in the Food and Drug Administration's prescribed set of early investigational new drug (IND)-enabling studies may be the first signs of ototoxicity properties of the new drug candidate. In developing improved and efficacious new molecular entities, it is critically necessary to understand the cellular and molecular mechanisms underlying the potential ototoxic effects as early in the drug development program as possible. Elucidation of these mechanisms will facilitate the development of safe and effective clinical approaches for the prevention and amelioration of drug-induced ototoxicity prior to the first dose in man. Biomarkers for nephrotoxicity in early tier I or tier II nonclinical IND-enabling studies should raise an inquiry as to the need to conduct a full auditory function assay early in the game to clear the pipeline with a safer candidate that has a higher probability of continued therapeutic compliance once approved for distribution.

Role of epigenetic mechanisms in cisplatin-induced toxicity

Cisplatin (CDDP) is a highly effective antineoplastic agent, widely used in the treatment of various malignant tumors. However, its major problems are side effects associated to toxicity. Considerable inter-individual differences have been reported for CDDP-induced toxicity due to genetic and epigenetic factors. Genetic causes are well described; however, epigenetic modifications are not fully addressed. In the last few years, many evidences were found linking microRNA to the development of CDDP-mediated toxicity, particularly nephrotoxicity. In this review, we described how genetic and epigenetic modifications can be important determinants for the development of toxicity in patients treated with CDDP, and how these alterations may be interesting biomarkers for monitoring toxicity induced by CDDP. Considering the validation in different studies, we suggest that miR-34a, -146b, -378a, -192, and -193 represent an attractive study group to evaluate potential biomarkers to detect CDDP-related nephrotoxicity.

Brief Overview: Assessment of Compound-induced Acute Kidney Injury Using Animal Models, Biomarkers, and In Vitro Platforms

The inability to unequivocally predict translatable drug-induced kidney injury in nonclinical studies during pharmacological development is evidenced by drug attrition in human clinical trials. Eight urinary proteins have been qualified as renal safety biomarkers for limited context of use in nonclinical drug development studies in rats. Formal qualification of human renal safety biomarkers is pending the submission of data from prospective clinical trials and analyses of biomarker performance to the Food and Drug Administration and European Medicines Agency by the Foundation for the National Institutes of Health and Predictive Safety Testing Consortium's Nephrotoxicity Working Group. In vitro kidney platforms may be leveraged to investigate the potential risk of compound-induced acute kidney injury and/or dysfunction. The early assessment of drug-related kidney safety profiles using biomarker-level changes in animal models and in vitro platforms could significantly reduce renal safety-related drug attrition; yet, there are no well-validated in vitro systems to enable comprehensive investigations of compound-induced nephrotoxicity. Thus, histopathology remains the gold standard for diagnosing nephron-specific damage. Traditional and emerging biomarker panels should be combined with histopathology and/or cytopathology to enable early identification of compound-induced kidney injury.

Cisplatin-Induced Rodent Model of Kidney Injury: Characteristics and Challenges

Cisplatin is an antitumor drug used in the treatment of a wide variety of malignancies. However, its primary dose-limiting side effect is kidney injury, which is a major clinical concern. To help understand mechanisms involved in the development of kidney injury, cisplatin rodent model has been developed. Given the complex pathogenesis of kidney injury, which involves both local events in the kidney and interconnected and interdependent systemic effects in the body, cisplatin rodent model is indispensable in the investigation of underlying mechanisms and potential treatment strategies of both acute and chronic kidney injury. Cisplatin rodent model is well appreciated and widely used model due to its simplicity. It has many similarities to human cisplatin nephrotoxicity, which are mentioned in the paper. In spite of its simplicity and wide applicability, there are also traps that need to be taken into account when using cisplatin model. The present paper is aimed at giving a concise insight into the complex characteristics of cisplatin rodent model and heterogeneity of cisplatin dosage regimens as well as outlining factors that can severely influence the outcome of the model and the study. Challenges for future research are also mentioned.

Urinary protein biomarkers of kidney injury in patients receiving cisplatin chemotherapy

Despite recent progress in the development of novel approaches to treat cancer, traditional antineoplastic drugs, such as cisplatin, remain a mainstay of regimens targeting solid tumors. Use of cisplatin is limited by acute kidney injury, which occurs in approximately 30% of patients. Current clinical measures, such as serum creatinine and estimated glomerular filtration rate, are inadequate in their ability to detect acute kidney injury, particularly when there is only a moderate degree of injury. Thus, there is an urgent need for improved diagnostic biomarkers to predict nephrotoxicity. There is also interest by the U.S. Food and Drug Administration to validate and implement new biomarkers to identify clinical and subclinical acute kidney injury in patients during the drug approval process. This minireview provides an overview of the current literature regarding the utility of urinary proteins (albumin, beta-2-microglobulin, N-acetyl-D-glucosaminidase, kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, and cystatin C) as biomarkers for cisplatin-induced AKI. Many of the well-studied urinary proteins (KIM-1, NGAL, B2M, albumin) as well as emerging biomarkers (calbindin, monocyte chemotactic protein-1, and trefoil factor 3) display distinct patterns of time-dependent excretion after cisplatin administration. Implementation of these biomarker proteins in the oncology clinic has been hampered by a lack of validation studies. To address these issues, large head-to-head studies are needed to fully characterize time-dependent responses and establish accurate cutoff values and ranges, particularly in cancer patients. Impact statement There is growing interest in using urinary protein biomarkers to detect acute kidney injury in oncology patients prescribed the nephrotoxic anticancer drug cisplatin. We aim to synthesize and organize the existing literature on biomarkers examined clinically in patients receiving cisplatin-containing chemotherapy regimens. This minireview highlights several proteins (kidney injury molecule-1, beta-2-microglobulin, neutrophil gelatinase-associated lipocalin, calbindin, monocyte chemotactic protein-1, trefoil factor 3) with the greatest promise for detecting cisplatin-induced acute kidney injury in humans. A comprehensive review of the existing literature may aid in the design of larger studies needed to implement the clinical use of these urinary proteins as biomarkers of kidney injury.

Performance of urinary neutrophil gelatinase-associated lipocalin, clusterin, and cystatin C in predicting diabetic kidney disease and diabetic microalbuminuria: a consecutive cohort study

Background

Tubular biomarkers have been regarded as emerging and promising markers for early diagnosis of diabetic kidney disease (DKD). The study was to determine the diagnostic capabilities of tubular biomarkers (urinary neutrophil gelatinase-associated lipocalin [NGAL], clusterin, and cystatin C) for DKD and diabetic microalbuminuria, and whether or not the tubular biomarkers appear earlier than microalbuminuria.

Methods

In this consecutive cohort study, 146 type 2 diabetes mellitus (T2DM) patients with a disease duration of ≥6 years were enrolled. Thirty age- and gender-matched subjects without any systemic diseases were recruited as the control group. Urinary samples collected before treatment were tested for NGAL, clusterin, and cystatin C.

Results

The levels of biomarkers were higher in patients with DKD (p < 0.001); and positively correlated with the urinary albumin creatinine ratio (UACR; p < 0.001). With respect to the diagnosis of DKD, the areas under the receiver operating characteristic curve (AUCs) for urinary NGAL, clusterin, and cystatin C were 0.816 (95% confidence interval [CI], 0.741–0.891), 0.775 (95% CI: 0.694–0.857), and 0.803 (95% CI: 0.722–0.884), respectively. The levels of urinary NGAL and cystatin C in the normoalbuminuria group (UACR <30 mg /g•Cr) were elevated compared with the control group, unlike urinary clusterin. There was no statistical difference in the levels of the three biomarkers between groups with different levels of haemoglobin A_1C (HbA_1c). The diagnostic AUCs for urinary NGAL, clusterin, and cystatin C in patients with diabetic microalbuminuria were 0.841 (95% CI: 0.775–0.907), 0.783(95% CI: 0.710–0.856), and 0.805 (95% CI: 0.733–0.877), respectively.

Conclusions

Urinary NGAL, clusterin, and cystatin C may be promising biomarkers for diagnosing DKD and diabetic microalbuminuria. It is possible that urinary NGAL and cystatin C increase before the onset of microalbuminuria in T2DM patients.

The 6R's of drug induced nephrotoxicity

Drug induced kidney injury is a frequent adverse event which contributes to morbidity and increased healthcare utilization. Our current knowledge of drug induced kidney disease is limited due to varying definitions of kidney injury, incomplete assessment of concurrent risk factors and lack of long term outcome reporting. Electronic surveillance presents a powerful tool to identify susceptible populations, improve recognition of events and provide decision support on preventative strategies or early intervention in the case of injury. Research in the area of biomarkers for detecting kidney injury and genetic predisposition for this adverse event will enhance detection of injury, identify those susceptible to injury and likely mitigate risk. In this review we will present a 6R framework to identify and mange drug induced kidney injury – risk, recognition, response, renal support, rehabilitation and research.

Cisplatin nephrotoxicity in male beagle dogs: next-generation protein kidney safety biomarker tissue expression and related changes in urine

This 10-day (D) study was conducted to evaluate changes in traditional and newer kidney safety biomarker expression levels in dogs. Animals received cisplatin (CDDP, 0.75 mg per kg per day) or 0.9% Saline (vehicle) for 5 days. Serum/urine samples were collected at various time points. Cage-side observations included emesis (D1-2/D4-D5/D7-9), absence of stool (D5-9/D11), soft stool (D4-7/D12), excessive salivation (D1/D3/D5-6), decreased food consumption (D5-8), decreased activity (D7-8) and/or dehydration (D7). Animals were necropsied when serum creatinine (sCr) levels measured at ≥1.9 mg dL^-1, indicating significant loss of renal function; or at the end of the study (D11). When compared to controls, increases in BUN/sCr were detected on D3, D5 and/or D8. Increases in urinary total protein (Ur TP) were noted on D6. The moribund dog that was euthanized early on D7 showed insignificant increases in urinary osteopontin (Ur OPN), urinary neutrophil gelatinase-associated lipocalin (Ur NGAL), urinary clusterin (Ur CLU), sCr, serum cystatin C (sCYS C) and urinary cystatin C (Ur CYS C) on D5 when compared to controls. Insignificant increases in urinary albumin (Ur ALB) were observed from an animal that was euthanized on D7 and 1 : 2 surviving animals on D8 relative to baseline. From three dogs that were euthanized on D9, increases in Ur CLU, and/or sCYS C were noted on D8 relative to baseline. The two surviving dogs showed elevated Ur CLU and 1 : 2 surviving dogs showed elevated Ur CYS C. Decreased urinary kidney injury molecule 1 (Ur KIM-1) on D3/D5 was evident (versus baseline and controls). CDDP-induced cortico-medullary lesions were characterized as minimal to mild tubule degeneration/necrosis, dilatation, regeneration, cell alteration, intratubular casts, interstitial inflammation and vacuolization. Increased Ur OPN and Ur CLU correlated with enhanced OPN and CLU immunopositive staining in damaged cortical epithelium in the proximal tubules. Enhanced KIM-1 staining in damaged cortico-medullary tubular epithelium appeared in the absence of rises in Ur KIM-1. This study showed changes in kidney safety protein biomarkers associated with CDDP nephrotoxicity in dogs and possibly in humans.

A Comprehensive Review on the Genetic Regulation of Cisplatin-induced Nephrotoxicity

Cisplatin (CDDP) is a well-known antineoplastic drug which has been extensively utilized over the last decades in the treatment of numerous kinds of tumors. However, CDDP induces a wide range of toxicities in a dose-dependent manner, among which nephrotoxicity is of particular importance. Still, the mechanism of CDDP-induced renal damage is not completely understood; moreover, the knowledge about the role of microRNAs (miRNAs) in the nephrotoxic response is still unknown. miRNAs are known to interact with the representative members of a diverse range of regulatory pathways (including postnatal development, proliferation, inflammation and fibrosis) and pathological conditions, including kidney diseases: polycystic kidney diseases (PKDs), diabetic nephropathy (DN), kidney cancer, and drug-induced kidney injury. In this review, we shed light on the following important aspects: (i) information on genes/proteins and their interactions with previously known pathways engaged with CDDP-induced nephrotoxicity, (ii) information on newly discovered biomarkers, especially, miRNAs for detecting CDDP-induced nephrotoxicity and (iii) information to improve our understanding on CDDP. This information will not only help the researchers belonging to nephrotoxicity field, but also supply an indisputable help for oncologists to better understand and manage the side effects induced by CDDP during cancer treatment. Moreover, we provide up-to-date information about different in vivo and in vitro models that have been utilized over the last decades to study CDDP-induced renal injury. Taken together, this review offers a comprehensive network on genes, miRNAs, pathways and animal models which will serve as a useful resource to understand the molecular mechanism of CDDP-induced nephrotoxicity.

Pyruvate Kinase M2: A Novel Biomarker for the Early Detection of Acute Kidney Injury

The identification of biomarkers for the early detection of acute kidney injury (AKI) is clinically important. Acute kidney injury (AKI) in critically ill patients is closely associated with increased morbidity and mortality. Conventional biomarkers, such as serum creatinine (SCr) and blood urea nitrogen (BUN), are frequently used to diagnose AKI. However, these biomarkers increase only after significant structural damage has occurred. Recent efforts have focused on identification and validation of new noninvasive biomarkers for the early detection of AKI, prior to extensive structural damage. Furthermore, AKI biomarkers can provide valuable insight into the molecular mechanisms of this complex and heterogeneous disease. Our previous study suggested that pyruvate kinase M2 (PKM2), which is excreted in the urine, is a sensitive biomarker for nephrotoxicity. To appropriately and optimally utilize PKM2 as a biomarker for AKI requires its complete characterization. This review highlights the major studies that have addressed the diagnostic and prognostic predictive power of biomarkers for AKI and assesses the potential usage of PKM2 as an early biomarker for AKI. We summarize the current state of knowledge regarding the role of biomarkers and the molecular and cellular mechanisms of AKI. This review will elucidate the biological basis of specific biomarkers that will contribute to improving the early detection and diagnosis of AKI.

Aging increases the susceptibility of cisplatin-induced nephrotoxicity

Cisplatin (CDDP) nephrotoxicity is one of the most common side effects in cancer treatment, causing the disruption of chemotherapy. In this study, we analyzed the influence of nongenetic factors on CDDP-induced nephrotoxiciy using the data from 182 CDDP-treated and 52 carboplatin (CBP)-treated patients. The mean change of eGFR (100% to baseline) in CDDP-treated patients was -9.2%, which was significantly lower than that in the population with CBP therapy. By using the chi-squared test and multivariate logistic regression analysis, age (≥50 years) is found associated with CDDP-induced nephrotoxicity, with odds ratio (OR) of 9.167 and 11.771, respectively. Three- and 18-month-old mice were employed to study the age-dependent susceptibility of CDDP-induced nephrotoxicity. Biochemical parameters, histopathogical examination, and mRNA biomarkers indicated that old mice were subjected to more severe kidney injury. In addition, old mice accumulated more CDDP in kidney than young mice, and the protein level of CDDP efflux transporter, MATE1, in aged mice kidney was 35% of that in young mice. Moreover, inflammatory receptor TLR4 was higher in the kidney of old mice, indicating the alteration of inflammatory signaling in old mice. After CDDP administration, the induced alterations of TNF-α, ICAM-1, and TLR4 were more extensive in old mice. To summarize, aging increased the susceptibility of CDDP-induced renal function decline or nephrotoxicity.

ILSI Health and Environmental Sciences Institute (HESI), global leader in advancing translational science to create science-based solutions for a sustainable, healthier world

The Health and Environmental Sciences Institute (HESI) is a non-profit scientific research organization based in Washington, D.C., U.S.A. HESI was established in 1989 as a global branch of the International Life Sciences Institute (ILSI) to provide an international forum to advance the understanding of scientific issues related to human health, toxicology, risk assessment and the environment. For the last 25 years, HESI has been the global leader to advance application of new science and technologies in the areas of human health, toxicology, risk assessment and environment. The core principle of “tripartite approach” and the multi-sector operational model have successfully supported HESI’s scientific programs to create science-based solutions for a sustainable and healthier world. HESI’s achievements include the dataset to guide the selection of appropriate supporting assays for carcinogenicity testing, a new testing framework for agricultural chemicals with enhanced efficacy, predictivity, and reduced animal usage, novel biomarkers of nephrotoxicity which provide data on the location of timing of drug effects in the kidney allowing for enhanced drug development, etc.

Calcium oxalate calculi-induced clusterin expression in kidney

The aim of the study was to investigate clusterin expression in the kidney and evaluate the urine clusterin level in the kidney stone formers. (1) In vitro, we treated the Madin-Darby canine kidney (MDCK) cell line with different concentrations of calcium oxalate (CaOx), and then the clusterin protein expression in the cells was evaluated by Western blotting. (2) Kidney stone patients who received percutaneous nephrolithotomy were enrolled in our study. Urine samples were collected before surgery, the kidney punctured to obtain kidney tissue guided by ultrasound intraoperatively. Clusterin expression in the human kidney tissue was evaluated by immunochemistry. The urine clusterin level was determined by enzyme-linked immunosorbent assay. Non-kidney disease subjects were chosen as controls. In vitro, the clusterin expression was up-regulated in the MDCK cells induced by CaOx. The study included 49 patients and 41 non-kidney disease subjects. All calculi were composed of calcium oxalate monohydrate or calcium oxalate dihydrate and a few also contained protein or uric acid. Mean ± SD urine clusterin level was 17.47 ± 18.61 μg/ml in patients, and 3.31 ± 5.42 μg/ml in non-kidney disease subjects, respectively (p < 0.001). Immunohistochemistry revealed the clusterin was located in the cytoplasm of the renal distal and collecting tubular epithelial cells. Also the tissue clusterin expression increased significantly in the kidney stone formers compared to the control groups (p = 0.001). CaOx could induce clusterin expression in renal tubular cells, and increase clusterin levels in the kidney and urine from the kidney stone formers.

Sub-nephrotoxic cisplatin sensitizes rats to acute renal failure and increases urinary excretion of fumarylacetoacetase

Nephrotoxicity limits the therapeutic efficacy of the antineoplastic drug cisplatin. Due to dosage adjustment and appropriate monitoring, most therapeutic courses with cisplatin produce no or minimal kidney damage. However, we studied whether even sub-nephrotoxic dosage of cisplatin poses a potential risk for the kidneys by predisposing to acute kidney injury (AKI), specifically by lowering the toxicity threshold for a second nephrotoxin. With this purpose rats were treated with a single sub-nephrotoxic dosage of cisplatin (3mg/kg, i.p.) and after two days, with a sub-nephrotoxic regime of gentamicin (50mg/kg/day, during 6 days, i.p.). Control groups received only one of the drugs or the vehicle. Renal function and renal histology were monitored throughout the experiment. Cisplatin treatment did not cause any relevant functional or histological alterations in the kidneys. Rats treated with cisplatin and gentamicin, but not those under single treatments, developed an overt renal failure characterized by both renal dysfunction and massive tubular necrosis. In addition, the urinary excretion of fumarylacetoacetase was increased in cisplatin-treated animals at subtoxic doses, which might be exploited as a cisplatin-induced predisposition marker. In fact, the urinary level of fumarylacetoacetase prior to the second nephrotoxin correlated with the level of AKI triggered by gentamicin in predisposed animals.

Nonclinical Safety and Toxicology

Nonclinical safety pharmacology and toxicology testing of drug candidates assess the potential adverse effects caused by the drug in relation to its intended use in humans. Hazards related to a drug have to be identified and the potential risks at the intended exposure have to be evaluated in comparison to the potential benefit of the drug. Preclinical safety is thus an integral part of drug discovery and drug development. It still causes significant attrition during drug development.Therefore, there is a need for smart selection of drug candidates in drug discovery including screening of important safety endpoints. In the recent years,there was significant progress in computational and in vitro technology allowing in silico assessment as well as high-throughput screening of some endpoints at very early stages of discovery. Despite all this progress, in vivo evaluation of drug candidates is still an important part to safety testing. The chapter provides an overview on the most important areas of nonclinical safety screening during drug discovery of small molecules.

Impact of Pathologists and Evaluation Methods on Performance Assessment of the Kidney Injury Biomarker, Kim-1

Attempts to characterize and formally qualify biomarkers for regulatory purposes have raised questions about how histological and histopathological methods impact the evaluation of biomarker performance. A group of pathologists was asked to analyze digitized images prepared from rodent kidney injury experiments in studies designed to investigate sources of variability in histopathology evaluations. Study A maximized variability by using samples from diverse studies and providing minimal guidance, contextual information, or opportunities for pathologist interaction. Study B was designed to limit interpathologist variability by using more uniform image sets from different locations within the same kidneys and allowing pathologist selected interactions to discuss and identify the location and injury to be evaluated but without providing a lexicon or peer review. Results from this study suggest that differences between pathologists and across models of disease are the largest sources of variability in evaluations and that blind evaluations do not generally make a significant difference. Results of this study generally align with recommendations from both industry and the U.S. Food and Drug Administration and should inform future studies examining the effects of common lexicons and scoring criteria, peer review, and blind evaluations in the context of biomarker performance assessment.

Recent Successes in the Identification, Development, and Qualification of Translational Biomarkers

The development of novel safety or efficacy biomarkers has increasingly been used to improve safety monitoring and minimize attrition during drug development; however, for new biomarkers, the failure rate can equal or exceed that of new chemical entities. Drug-induced kidney injury is recognized to occur throughout the drug development process, with histopathology considered to be the gold standard for preclinical toxicologic screening. Renal biomarkers used clinically are primarily biomarkers of renal function and are considered insensitive for the detection of drug-induced kidney injury during first-in-man studies, particularly for compounds known to induce renal injury in preclinical species. Recent efforts by public–private partnerships have led to unprecedented success in the identification, development, and qualification of several new translatable biomarkers of kidney injury in the rat. To optimize the chance of success in current and future biomarker efforts in preclinical species and man, selection and development of biomarkers should emphasize biological considerations including marker variability and biology in both health and disease. The research to support the qualification of novel renal safety markers for routine use in the clinical setting is currently underway, and results from this work are greatly anticipated.

Effect of infliximab against cisplatin-induced nephrotoxicity

OBJECTIVES

To investigate whether infliximab (Ib), an inhibitor of tumor necrosis factor alpha (TNF-α), prevents cisplatin (Cis)-induced nephrotoxicity.

METHODS

The study was performed in the Department of Internal Medicine, Recep Tayyip Erdogan University, Rize, Turkey, between November 2012 and May 2013. Thirty male Wistar albino rats were divided into 3 groups, a control group, a Cis group, and a Cis+Ib group. The animals of the Cis group were injected with a single dose (7 mg/kg) of Cis intraperitoneally. The animals of the Cis+Ib group were injected with a single dose (7 mg/kg) of Ib 72 hours prior to Cis injection.

RESULTS

The TNF-α, interleukin-1 beta (IL-1b), nitric oxide (NO) and adenosine deaminase (ADA) levels of the Cis group were higher than both the control group TNF-α (p<0.001), IL-1α (p<0.001), NO (p<0.001) and ADA (p<0.001), and the Cis+Ib group TNF-α (p<0.001), IL-1b (p<0.001), NO (p<0.001), and ADA (p=0.003). Histopathological examination revealed extensive damage in the Cis group, while the damage in the Cis+Ib group was lower. While the carbonic anhydrase II (CA-II) level of the Cis group was lower than both groups, it was similar in the Cis+Ib and the control groups.

CONCLUSION

Infliximab acts against Cis-induced nephrotoxicity by a strong inhibition of TNF-α. Additionally, the combination of these 2 drugs does not obviously change the level of CA-II.

Usefulness of urinary kidney injury molecule-1 (Kim-1) as a biomarker for cisplatin-induced sub-chronic kidney injury

We explored biomarkers suitable for monitoring sub-chronic kidney injury using the three rat models of cisplatin (CDDP)-induced kidney injury, which were designed to extend the current knowledge beyond the sub-acute exposure period. In the pilot study, a single intravenous administration of 1.5 mg kg(-1) CDDP to rats was confirmed to result in no histopathological changes. Subsequently, CDDP was intravenously administered to rats at a dose of 1.5 mg kg(-1) for 4 days at 24-h intervals (Experimental model 1) and for up to 10 weeks at weekly intervals (Experimental models 2 and 3), and the changes in blood and urine components, such as recently recommended urinary biomarkers (Kim-1, clusterin and so on) and traditional blood biomarkers (blood urea nitrogen and serum creatinine), were examined together with the histopathological changes in renal tissues during the development of the kidney injury in each model. In these experimental models, a significant increase in urinary Kim-1 was observed prior to the histopathological changes in renal tissues, and these changes were retained after the adverse histopathological changes. Significant changes in all of the other urinary biomarkers examined occurred along with the histopathological changes. In addition, the increase in urinary Kim-1 after weekly treatment with CDDP for 4 weeks was reduced in a time-dependent manner after cessation of the drug. The present findings indicate that urinary Kim-1 is the most useful biomarker for CDDP-induced rat sub-chronic kidney injury among the biomarkers examined.

MicroRNA-34c-3p is an early predictive biomarker for doxorubicin-induced glomerular injury progression in male Sprague-Dawley rats

Increased microRNA-34c-3p appeared as a novel biomarker for doxorubicin nephrotoxicity in rats; alterations showed greater specificity than and comparable sensitivity to albuminuria for early prediction of glomerular injury.

Isolation of urinary exosomes for RNA biomarker discovery using a simple, fast, and highly scalable method

Urinary exosomes are nanovesicles (40-100 nm) of endocytic origin that are secreted into the urine when a multivesicular body fuses with the membrane of cells from all nephron segments. Interest in urinary exosomes intensified after the discovery that they contain not only protein and mRNA but also microRNA (miRNA) markers of renal dysfunction and structural injury. Currently, the most widely used protocol for the isolation of urinary exosomes is based on ultracentrifugation, a method that is time consuming, requires expensive equipment, and has low scalability, which limits its applicability in the clinical practice. In this chapter, a simple, fast, and highly scalable step-by-step method for isolation of urinary exosomes is described. This method starts with a 10-min centrifugation of 10 ml urine, then the supernatant is saved (SN1), and the pellet is treated with dithiothreitol and heat to release and recover those exosomes entrapped by polymeric Tamm-Horsfall protein. The treated pellet is then resuspended and centrifuged, and the supernatant obtained (SN2) is combined with the first supernatant, SN1. Next, 3.3 ml of ExoQuick-TC, a commercial exosome precipitation reagent, is added to the total supernatant (SN1 + SN2), mixed well, and saved for at least 12 h at 4 °C. Finally, a pellet of exosomes is obtained after a 30-min centrifugation of the supernatant/ExoQuick-TC mix. We previously compared this method with five others used to isolate urinary exosomes and found that this is the simplest, fastest, and most effective alternative to ultracentrifugation-based protocols if the goal of the study is RNA profiling. A method for isolation and quantification of miRNAs and mRNAs from urinary exosomes is also described here. In addition, we provide a step-by-step description of exosomal miRNA profiling using universal reverse transcription and SYBR qPCR.

Effect of stem cell therapy on adriamycin induced tubulointerstitial injury

BACKGROUND AND OBJECTIVES

It was postulated that adriamycin (ADR) induce renal tubulointerstitial injury. Clinicians are faced with a challenge in producing response in renal patients and slowing or halting the evolution towards kidney failure. The present study aimed at investigating the relation between the possible therapeutic effect of human mesenchymal stem cells (HMSCs), isolated from cord blood on tubular renal damage and their distribution by using ADR induced nephrotoxicity as a model in albino rat.

METHODS AND RESULTS

Thirty three male albino rats were divided into control group, ADR group where rats were given single intraperitoneal (IP) injection of 5 mg/kg adriamycin. The rats were sacrificed 10, 20 and 30 days following confirmation of tubular injury. In stem cell therapy group, rats were injected with HMSCs following confirmation of renal injury and sacrificed 10, 20 and 30 days after HMSCs therapy. Kidney sections were exposed to histological, histochemical, immunohistochemical, morphometric and serological studies. In response to SC therapy, vacuolated cytoplasm, dark nuclei, detached epithelial lining and desquamated nuclei were noticed in few collecting tubules (CT). 10, 20 and 30 days following therapy. The mean count of CT showing desquamated nuclei and mean value of serum creatinine revealed significant difference in ADR group. The mean area% of Prussian blue+ve cells and that of CD105 +ve cells measured in subgroup S1 denoted a significant increase compared to subgroups S2 and S3.

CONCLUSIONS

ADR induced tubulointerstitial damage that regressed in response to cord blood HMSC therapy.

Tissue regeneration and stem cell distribution in adriamycin induced glomerulopathy

BACKGROUND AND OBJECTIVES

Glomerulosclerosis develops secondary to various kidney diseases. It was postulated that adriamycin (ADR) induce chronic glomerulopathy. Treatment combinations for one year did not significantly modify renal function in resistant focal segmental glomerulosclerosis (FSGS). Recurrence of FSGS after renal transplantation impacts long-term graft survival and limits access to transplantation. The present study aimed at investigating the relation between the possible therapeutic effect of human mesenchymal stem cells (HMSCs), isolated from cord blood on glomerular damage and their distribution by using ADR induced nephrotoxicity as a model in albino rat.

METHODS AND RESULTS

Thirty three male albino rats were divided into control group, ADR group where rats were given single intraperitoneal (IP) injection of 5 mg/kg adriamycin. The rats were sacrificed 10, 20 and 30 days following confirmation of glomerular injury. In stem cell therapy group, rats were injected with HMSCs following confirmation of renal injury and sacrificed 10, 20 and 30 days after HMSCs therapy. Kidney sections were exposed to histological, histochemical, immunohistochemical, morphometric and serological studies. In response to SC therapy multiple Malpighian corpuscles (MC) appeared with patent Bowman's space (Bs) 10 and 20 days following therapy. One month following therapy no remarkable shrunken glomeruli were evident. Glomerular area and serum creatinine were significantly different in ADR group in comparison to control and SC therapy groups.

CONCLUSIONS

ADR induced glomerulosclerosis regressed in response to cord blood HMSC therapy. A reciprocal relation was recorded between the extent of renal regeneration and the distribution of undifferentiated mesenchymal stem cells.

Assessment Standards

Histopathology generally represents the reference standard for performance evaluation of nonclinical biomarkers used to inform regulatory decision making. This study uses drug-induced nephrotoxicity in rats to evaluate histopathology methods utilized in biomarker performance assessments. Male Sprague-Dawley rats received a single dose of cisplatin (0.5–5.0 mg/kg, intraperitoneally) to produce mild renal injury. Animals were euthanized 72 hr postdose and perfusion fixed. Kidneys were processed for histology and stereology procedures. Kidney injury molecule-1 (Kim-1) was measured in urine and in kidney tissue. Digital slide images were generated and analyzed by pathologists after collaborating on a training set of glass slides and digital images. Image analysis identified immunohistochemistry (IHC)-defined tubular injury. Stereology methods yielded estimations of proximal tubular cell number and volume. Statistical relationships among data sets were determined using correlation coefficients. Receiver operator characteristic (ROC) analyses determined the effect of method on biomarker assessment. Urinary Kim-1 was strongly correlated with digital image analysis and secondarily to histopathology evaluations. Stereology demonstrated weak or no correlation to pathology and urinary Kim-1. In ROC analyses, semiquantitative evaluations determined higher values for urinary Kim-1 performance than did IHC-based qualitative digital analyses. Semiquantitative evaluation as used in this study was most predictive of urinary Kim-1 values.

Neutrophil gelatinase-associated lipocalin, a sensitive urinary biomarker of acute kidney injury in dogs receiving gentamicin

A sensitive urinary biomarker for acute kidney injury (AKI) was investigated in beagle dogs with nephrotoxicity induced by gentamicin. Gentamicin sulphate at 25 or 50 mg/kg was injected (s.c.) for 9 days, and conventional urinalysis, ELISA assay of neutrophil gelatinase-associated lipocal (NGAL) in urine, blood chemistry, and pathological examinations were performed. The dog given gentamicin at 25 mg/kg only showed slight deposition of lysosomal granules in the proximal tubular epithelium of the kidneys without any other significant changes even though urinary NGAL was elevated on Day 10 (day of necropsy). In the dog receiving gentamicin at 50 mg/kg, increases in urinary NGAL were observed on Days 3 and 5, and absence of urination, marked increases in serum urea nitrogen and creatinine, enlargement and discoloration of the kidneys with marked necrosis, and swelling of proximal epithelium were observed. In conclusion, urinary NGAL is considered to be a candidate as a sensitive predictable biomarker of AKI in the gentamicin-induced nephrotoxicity model in dogs.

Prediction of clinically relevant safety signals of nephrotoxicity through plasma metabolite profiling

Addressing safety concerns such as drug-induced kidney injury (DIKI) early in the drug pharmaceutical development process ensures both patient safety and efficient clinical development. We describe a unique adjunct to standard safety assessment wherein the metabolite profile of treated animals is compared with the MetaMap Tox metabolomics database in order to predict the potential for a wide variety of adverse events, including DIKI. To examine this approach, a study of five compounds (phenytoin, cyclosporin A, doxorubicin, captopril, and lisinopril) was initiated by the Technology Evaluation Consortium under the auspices of the Drug Safety Executive Council (DSEC). The metabolite profiles for rats treated with these compounds matched established reference patterns in the MetaMap Tox metabolomics database indicative of each compound's well-described clinical toxicities. For example, the DIKI associated with cyclosporine A and doxorubicin was correctly predicted by metabolite profiling, while no evidence for DIKI was found for phenytoin, consistent with its clinical picture. In some cases the clinical toxicity (hepatotoxicity), not generally seen in animal studies, was detected with MetaMap Tox. Thus metabolite profiling coupled with the MetaMap Tox metabolomics database offers a unique and powerful approach for augmenting safety assessment and avoiding clinical adverse events such as DIKI.

Bioengineered 3D human kidney tissue, a platform for the determination of nephrotoxicity

The staggering cost of bringing a drug to market coupled with the extremely high failure rate of prospective compounds in early phase clinical trials due to unexpected human toxicity makes it imperative that more relevant human models be developed to better predict drug toxicity. Drug–induced nephrotoxicity remains especially difficult to predict in both pre-clinical and clinical settings and is often undetected until patient hospitalization. Current pre-clinical methods of determining renal toxicity include 2D cell cultures and animal models, both of which are incapable of fully recapitulating the in vivo human response to drugs, contributing to the high failure rate upon clinical trials. We have bioengineered a 3D kidney tissue model using immortalized human renal cortical epithelial cells with kidney functions similar to that found in vivo. These 3D tissues were compared to 2D cells in terms of both acute (3 days) and chronic (2 weeks) toxicity induced by Cisplatin, Gentamicin, and Doxorubicin using both traditional LDH secretion and the pre-clinical biomarkers Kim-1 and NGAL as assessments of toxicity. The 3D tissues were more sensitive to drug-induced toxicity and, unlike the 2D cells, were capable of being used to monitor chronic toxicity due to repeat dosing. The inclusion of this tissue model in drug testing prior to the initiation of phase I clinical trials would allow for better prediction of the nephrotoxic effects of new drugs.

Correlation of histopathology, urinary biomarkers, and gene expression responses following hexachloro-1:3-butadiene-induced acute nephrotoxicity in male Hanover Wistar rats: a 28-day time course study

Hexachloro-1:3-butadiene (HCBD) causes segment-specific injury to the proximal renal tubule. A time course study of traditional and more recently proposed urinary biomarkers was performed in male Hanover Wistar rats receiving a single intraperitoneal (ip) injection of 45 mg/kg HCBD. Animals were killed on days 1, 2, 3, 4, 5, 6, 7, 10, 14, and 28 postdosing and the temporal response of renal biomarkers was characterized using kidney histopathology, urinary and serum biochemistry, and gene expression. Histopathologic evidence of tubular degeneration was seen from day 1 until day 3 postdosing and correlated with increased urinary levels of α-glutathione S-transferase (α-GST), albumin, glucose, and kidney injury molecule-1 (KIM-1), and increased gene expression of KIM-1, NAD(P)H dehydrogenase, quinone 1, and heme oxygenase (decycling) 1. Histopathologic evidence of tubular regeneration was seen from day 2 postdosing and correlated with raised levels of urinary KIM-1 and osteopontin and increased gene expression of KIM-1 and annexin A7. Traditional renal biomarkers generally demonstrated low sensitivity. It is concluded that in rat proximal tubular injury, measurement of a range of renal biomarkers, in conjunction with gene expression analysis, provides an understanding of the extent of degenerative changes induced in the kidney and the process of regeneration.

Qualified kidney biomarkers and their potential significance in drug safety evaluation and prediction

The kidney is one of the major organs drug toxicity may target. Some renal safety biomarkers have been proposed to measure kidney injury and function accordingly. Despite the widespread use for diagnosis and monitoring of renal injury and function for decades, serum creatinine and blood urea nitrogen are nonspecific biomarkers with insensitive and delayed response in the clinical setting. There is an urgent need to identify and qualify novel kidney safety biomarkers that would be used to detect and predict drug-induced nephrotoxicity in preclinical toxicological studies, clinical trials and patient care in sequence. To do that, eight novel renal safety biomarkers have been well characterized and qualified for preclinical drug safety screening, and their clinical bridging validation is underway as well. Of them, some are used to detect or predict proximal tubular injury, and others are used to diagnose and monitor glomerular damage. Thus, measurement of a panel of kidney safety biomarkers in parallel would help maximally capture all potential safety signals for a more informative decision to be made in drug research and development as well as for optimal selection of the drug and its dose in clinical practice.