A panel of urinary biomarkers to monitor reversibility of renal injury and a serum marker with improved potential to assess renal function

Grouping approaches based on structure alone are insufficient to conclude about toxicological properties-the example of monoamine-based chelates

Aminocarboxylic acid (monoamine-based) chelating agents such as GLDA, MGDA, NTA, and EDG are widely used in a variety of products and processes. In the European Union, based on the Green Deal and the Chemicals Strategy for Sustainability (CSS), there is an increasing tendency to speed up chemical hazard evaluation and to regulate chemicals by grouping substances based on molecular structure similarity. Recently, it was proposed to group polycarboxylic acid monoamines, hydroxy derivatives and their salts with monovalent cations, and to consider all group members as potential carcinogens based on the official CLP classification of one group member, viz. NTA, which is classified as suspected carcinogen Cat. 2. In this review, we show that a grouping approach for harmonized classification and labeling based on molecular structure alone, disregarding existing animal test data as well as current scientific and regulatory knowledge, would result in incorrect classification. Using such a simplistic, although considered pragmatic approach, classification of all group members upfront would not improve protection of human health. Instead, it could not only lead to unnecessary additional vertebrate animal testing but also to onerous and disproportionate restrictions being placed on the use of these valuable substances; some of these even being considered as green chemicals.

Vanin-1-Activated Chemiluminescent Probe: Help to Early Diagnosis of Acute Kidney Injury with High Signal-to-Noise Ratio through Urinalysis

Acute kidney injury (AKI) is a common medical condition with high morbidity and mortality. Although urinalysis provides a noninvasive and convenient diagnostic method for AKI at the molecular level, the low sensitivity of current chemical probes used in urinalysis hinders the time diagnosis of AKI. Herein, we achieved the sensitive and early diagnosis of AKI by the development of a chemiluminescent probe CL-Pa suitable for detection of urinary Vanin-1. Vanin-1 is considered as an early and sensitive biomarker for AKI, while few chemical probes have been applied to for its efficient detection. By virtue of the low autofluorescence interference during urine imaging in the chemiluminescence model, CL-Pa could realize the monitoring of the up-regulated urinary Vanin-1 with a high signal-to-noise ratio (∼588). Importantly, under the help of CL-Pa, the up-regulation of urinary Vanin-1 of cisplatin-induced AKI mice at 12 h post cisplatin injection was detected, which was much earlier than clinical biomarkers (sCr and BUN) and change of kidney histology (48 h post cisplatin injection). Furthermore, using this probe, the fluctuation of urinary Vanin-1 of mice with different degrees of AKI was monitored. This study demonstrated the ability of CL-Pa in sensitively detecting drug-induced AKI through urinalysis and suggested the great potential of CL-Pa for early diagnosis of AKI and evaluate the efficiency of anti-AKI drugs clinically.

The evolving role of investigative toxicology in the pharmaceutical industry

For decades, preclinical toxicology was essentially a descriptive discipline in which treatment-related effects were carefully reported and used as a basis to calculate safety margins for drug candidates. In recent years, however, technological advances have increasingly enabled researchers to gain insights into toxicity mechanisms, supporting greater understanding of species relevance and translatability to humans, prediction of safety events, mitigation of side effects and development of safety biomarkers. Consequently, investigative (or mechanistic) toxicology has been gaining momentum and is now a key capability in the pharmaceutical industry. Here, we provide an overview of the current status of the field using case studies and discuss the potential impact of ongoing technological developments, based on a survey of investigative toxicologists from 14 European-based medium-sized to large pharmaceutical companies.

Efficacy and safety of long-term postpartum antiviral therapy in hepatitis B virus-infected mothers receiving prophylactic tenofovir disoproxil fumarate treatment

OBJECTIVES

This study aimed to evaluate the efficacy and safety of long-term postpartum tenofovir disoproxil fumarate (TDF) therapy in hepatitis B virus (HBV)-infected mothers with high viral load.

METHODS

In this retrospective cohort study, HBV-infected mothers with HBV DNA>2 × 10 5  IU/mL who initiated TDF prophylaxis treatment during pregnancy were divided into TDF continuation and discontinuation groups according to whether they stopped TDF treatment within 3 months after birth or not. Virological and biochemical markers were collected before TDF treatment, antepartum and postpartum.

RESULTS

In 131 women followed for a median of 18 months postpartum, alanine aminotransferase (ALT) abnormality rate was significantly lower in TDF continuation group vs. discontinuation group (39.4% vs. 56.9%, P  = 0.045), and continuous TDF therapy in postpartum was independently associated with lower risk of ALT flares [OR = 0.308, 95% confidence interval (CI), 0.128-0.742; P  = 0.009]. Long-term postpartum TDF treatment can promote the decline of hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) levels, but the HBeAg seroconversion rate in two groups was not significant (15.5% vs. 11.7%, P  = 0.541). There were no statistical differences in bone metabolism markers between two groups ( P  > 0.05). Compared with the TDF discontinuation group, TDF continuation group had a significantly lower estimated glomerular filtration rate level and higher creatinine level in postpartum but within normal ranges ( P  < 0.05).

CONCLUSIONS

For pregnant women who received prophylactic TDF treatment, long-term TDF therapy continued in postpartum can reduce the risk of ALT flares and promote the rapid decline of HBeAg and HBsAg levels.

Suppression of lncRNA GAS6-AS2 alleviates sepsis-related acute kidney injury through regulating the miR-136-5p/OXSR1 axis in vitro and in vivo

Acute kidney injury (AKI) is a common complication of sepsis and increase morbidity and mortality. Long non-coding RNA (LncRNA) GAS6-AS2 was related to inflammation and apoptosis in different diseases by regulating miRNAs and downstream genes, but its role in AKI remains unclear. Thus, we speculated that GAS6-AS2 might function in sepsis-related AKI via regulating target genes. Here, LPS or CLP was used to establish in vitro or in vivo sepsis-related AKI model. The interactions between GAS6-AS2 and miR-136-5p, and miR-136-5p and OXSR1, were validated by luciferase reporter assay, RNA pull-down, or RIP assay. Cell apoptosis was determined by flow cytometry, Western blotting, or IHC. The kidney injury was evaluated by H&E staining. The expression of GAS6-AS2, miR-136-5p, and OXSR1 was determined by qRT-PCR or Western blotting. We found that GAS6-AS2 was up-regulated in LPS-treated HK2 cells and the CLP-induced rat model. In vitro, GAS6-AS2 knockdown decreased cleaved caspase-3 and bax expression and increased bcl-2 expression. The levels of TNF-α, IL-1β, and IL-6 were reduced by GAS6-AS2 down-regulation. GAS6-AS2 knockdown ameliorated oxidative stress in the cells, as indicated by the reduced ROS and MDA levels and the elevated SOD level. In vivo, GAS6-AS2 down-regulation decreased urinary NGAL and Kim-1 levels and serum sCr and BUN levels, and H&E proved that the kidney injury was alleviated. GAS6-AS2 knockdown also reduced apoptosis, inflammation, and oxidation induced by CLP in vivo. Mechanically, GAS6-AS2 sponged miR-136-5p which targeted OXSR1. Overall, lncRNA GAS6-AS2 knockdown has the potential to ameliorate sepsis-related AKI, and the mechanism is related to miR-136-5p/OXSR1 axis.

Megalin, a multi-ligand endocytic receptor, and its participation in renal function and diseases: A review

The endocytosis mechanism is a complicated system that is essential for cell signaling and survival. Megalin, a membrane-associated endocytic receptor, and its related proteins such as cubilin, the neonatal Fc receptor for IgG, and NaPi-IIa are important in receptors-mediated endocytosis. Physiologically, megalin uptakes plasma vitamins and proteins from primary urine, preventing their loss. It also facilitates tubular retrieval of solutes and endogenous components that may be involved in modulation and recovery from kidney injuries. Moreover, megalin is responsible for endocytosis of xenobiotics and drugs in renal tubules, increasing their half-life and/or their toxicity. Fluctuations in megalin expression and/or functionality due to changes in its regulatory mechanisms are associated with some sort of kidney injury. Also, it's an important component of several pathological conditions, including diabetic nephropathy and Dent disease. Thus, exploring the fundamental role of megalin in the kidney might help in the protection and/or treatment of multiple kidney-related diseases. Hence, this review aimed to explore the physiological roles of megalin in the kidney and their implications for kidney-related injuries.

Biomarker-Guided Individualization of Antibiotic Therapy

Treatment failure of antibiotic therapy due to insufficient efficacy or occurrence of toxicity is a major clinical challenge, and is expected to become even more urgent with the global rise of antibiotic resistance. Strategies to optimize treatment in individual patients are therefore of crucial importance. Currently, therapeutic drug monitoring plays an important role in optimizing antibiotic exposure to reduce treatment failure and toxicity. Biomarker-based strategies may be a powerful tool to further quantify and monitor antibiotic treatment response, and reduce variation in treatment response between patients. Host response biomarkers, such as CRP, procalcitonin, IL-6, and presepsin, could potentially carry significant information to be utilized for treatment individualization. To achieve this, the complex interactions among immune system, pathogen, drug, and biomarker need to be better understood and characterized. The purpose of this tutorial is to discuss the use and evidence of currently available biomarker-based approaches to inform antibiotic treatment. To this end, we also included a discussion on how treatment response biomarker data from preclinical, healthy volunteer, and patient-based studies can be further characterized using pharmacometric and system pharmacology based modeling approaches. As an illustrative example of how such modeling strategies can be used, we describe a case study in which we quantitatively characterize procalcitonin dynamics in relation to antibiotic treatments in patients with sepsis.

Proteome Analysis of Urinary Biomarkers in Acute Hypercoagulable State Rat Model

Thrombotic diseases are usually preceded by a hypercoagulable state in the body. This study aimed to screen potential urinary biomarkers for hypercoagulable state based on proteome analysis. Wistar rats were administered with the hemostatic agent etamsylate to establish hypercoagulable state. Urine samples were collected for proteome analysis. We found 20 proteins with levels more than 1.5-fold in difference between control rats and model rats. We searched human homologs of 20 rat proteins and identified 13 human proteins. Of the 13 human homologous proteins, nine were members of human core urinary proteome. Human homologous proteins of differential proteins were highly expressed in 31 human tissues, especially in the kidneys followed by digestive system and reproductive system. Surprisingly, we did not identify known coagulation factors as differential proteins in the urine of model rats. Hypercoagulable state of the body may not involve direct changes in coagulation factors but causes the changes upstream of the coagulation cascade system. Common differential urinary proteins between different hypercoagulable states suggest some common pathways in the formation of hypercoagulable states and may serve as potential biomarkers for the prevention and treatment of thrombotic diseases.

Exploration of zebrafish larvae as an alternative whole-animal model for nephrotoxicity testing

Due to an increasing demand for testing of new and existing chemicals and legal restrictions for the use of animals, there is a strong need for alternative approaches to assess systemic toxicity. Embryonic and larval zebrafish (Danio rerio) are increasingly recognized as a promising alternative whole-animal model that may be able to overcome limitations of cell-based in vitro assays and bridge the gap between high-throughput in vitro screening and low-throughput in vivo tests in animals. Despite the relatively simple anatomical structure of the zebrafish larval kidney (pronephros) - composed of only two nephrons - the pronephros shares major functions and cell types with mammalian nephrons. Glomerular filtration begins at 48 h post fertilization. The aim of the present study was to investigate if early zebrafish larvae might be a suitable model for nephrotoxicity testing. On day 3 post fertilization, larval zebrafish were treated with selected nephrotoxins (aristolochic acid, cadmium chloride, potassium bromate, ochratoxin A, gentamicin) for 48 h. Histological evaluation of zebrafish larvae exposed to model nephrotoxins revealed tubule injury as evidenced by dilated tubules with loss of the brush border, tubule cell necrosis and disorganization of the tubular epithelium. These changes were most severe after treatment with gentamicin, which also impaired pronephros function as evidenced by reduced clearance of FITC-dextran. Whole-mount in situ hybridization showing loss of cdh17 expression revealed site-specific injury to the proximal tubule segment. Analysis of genes previously identified as novel biomarkers of kidney injury in mammals showed upregulation of the kidney injury marker genes heme oxygenase 1 (hmox1), clusterin (clu), secreted phosphoprotein/osteopontin (spp1), connective tissue growth factor (ctgf) and kim-1 (havcr-1) in response to nephrotoxin treatment, although the response of individual genes varied across compounds. Consistent with the severity of lesions and impaired kidney function, the most prominent gene expression changes occurred in larvae exposed to gentamicin. Overall, our results suggest that larval zebrafish may be a suitable alternative model organism for nephrotoxicity screening, yet further improvements and integration with quantitative in vitro to in vivo extrapolation will be needed to predict human toxicity.

A Review of Specific Biomarkers of Chronic Renal Injury and Their Potential Application in Nonclinical Safety Assessment Studies

A host of novel renal biomarkers have been developed over the past few decades which have enhanced monitoring of renal disease and drug-induced kidney injury in both preclinical studies and in humans. Since chronic kidney disease (CKD) and acute kidney injury (AKI) share similar underlying mechanisms and the tubulointerstitial compartment has a functional role in the progression of CKD, urinary biomarkers of AKI may provide predictive information in chronic renal disease. Numerous studies have explored whether the recent AKI biomarkers could improve upon the standard clinical biomarkers, estimated glomerular filtration rate (eGFR), and urinary albumin to creatinine ratio, for predicting outcomes in CKD patients. This review is an introduction to alternative assays that can be utilized in chronic (>3 months duration) nonclinical safety studies to provide information on renal dysfunction and to demonstrate specific situations where these assays could be utilized in nonclinical drug development. Novel biomarkers such as symmetrical dimethyl arginine, dickkopf homolog 3, and cystatin C predict chronic renal injury in animals, act as surrogates for GFR, and may predict changes in GFR in patients over time, ultimately providing a bridge from preclinical to clinical renal monitoring.

Renoprotective effects of estrogen on acute kidney injury: the role of SIRT1

Acute kidney injury (AKI) is a common syndrome associated with high morbidity and mortality, despite progress in medical care. Many studies have shown that there are sex differences and different role of sex hormones particularly estrogens in kidney injury. In this regard, the incidence and rate of progression of kidney diseases are higher in men compared with women. These observations suggest that female sex hormone may be renoprotective. Silent information regulator 2 homolog 1 (SIRT1) is a histone deacetylase, which is implicated in multiple biologic processes in several organisms. In the kidneys, SIRT1 inhibits renal cell apoptosis, inflammation, and fibrosis. Studies have reported a link between SIRT1 and estrogen. In addition, SIRT1 regulates ERα expression and inhibition of SIRT1 activity suppresses ERα expression. This effect leads to inhibition of estrogen-responsive gene expression. In this text, we review the role of SIRT1 in mediating the protective effects of estrogen in the onset and progression of AKI.

Role of Olive leaves Zinc Oxide Nanoparticles in Alleviating The Molecular and Histological Changes of Kidney in Female Goats-Induced by Gentamicin (Part III)

This study aimed to investigate the protective influence of olive leave extract zinc oxide nanoparticles (OLEZnONPs) complex against gentamicin–induced kidney dysfunctions in goats. Twenty five adult female goats were randomly divided into five equal groups and treated as follows: control group (C) administered sterile distilled water (IM) for 10 days, group G administered 25 mg/kg BW gentamicin (IM) for 7 days, group Z administered 10 ìg/kg BW of OLEZnONPs (IP) for 3 days, group GTZ administered 25 mg/kg BW gentamicin (IM) for 7 days and then 10 ìg/kg BW of OLEZnONPs (IP) for 3 days, group GWZ administered 25 mg/kg BWs gentamicin (IM) and 10 ìg/kg BW of OLEZnONPs (IP) together for first 3 days and then followed by gentamicin only for 4 days. After seven days of the experiment, the gene expression of kidney injury molcule-1(KIM-1) and neutrophil gelatinase-association lipocalin (NGAL) gene expression of kidney tissue were measured. In addition, samples of kidney were obtained for histopathological examination. Gentamicin medication induced a marked elevation in kidney tissue KIM-1 and NGAL gene expression in G and GTZ groups compared to control and other groups. Intraperitoneal treatment of goats with OLEZnONPs did not significantly affect NGAL and KIM-1 gene expression in Z, GWZ, and control groups. Histologically, in contrast to control, gentamicin induced more extensive kidney damages such as necrotized glomeruli, atrophic glomeruli, and renal tubular epithelial necrosis, while it was found that these alterations in kidney tissues wereimproved in goats given OLEZnONPs with gentamicin compared to group G. In conclusion, our results demonstrate that OLEZnONPs reduce the deleterious effects of gentamicin with significantly decreasing of KIM-1 and NGAL gene expression and remodeling the histological changes of kidney in goats.

Biochemical and histomorphological findings in Swiss Wistar rats treated with potential boron-containing therapeutic - K2[B3O3F4OH]

BACKGROUND

Boron and boron containing compounds are known for their biological and protective roles being non-toxic and non-mutagenic in low concentrations. Male rats were exposed to halogenated boroxine (HB), dipotassium-trioxohydroxytetrafluorotriborate K₂[B₃O₃F₄OH], a potential new boron-containing therapeutic, aiming to determine concentrations with no adverse effects on selected serum biochemical parameters and histomorphological features.

METHODS

HB was prepared by reacting potassium hydrofluoride (KHF₂) with boric acid in molar ratios 2:3 at room temperature and its primary structure contains 4 fluorine atoms substituted in 6-membered ring. In concentrations of 10, 25, 35 and 45 mg/kg, HB was administered intraperitoneally as a single dose. Biochemical parameters were observed 24 and 96 h following the treatment. Effects of HB on biochemical blood parameters were also observed 24 h following continuous nine days application in concentrations of 10 mg/kg intraperitoneally and 50 mg/kg per os. Histomorphological observation of kidneys, liver, spleen, lungs and heart was performed for all treated animals.

RESULTS

Administration of single high dose of HB (35 mg/kg-45 mg/kg) effected high levels of urea and creatinine, which indicated renal injury that appeared to be temporary. Possible cause of concern is pancreatic injury indicated by elevated levels of serum amylase in the groups of animals that received the highest dosages of the substance. Histopathological examination of selected tissues revealed mild to moderate lesions in the kidneys and livers associated with administration of HB.

CONCLUSION

Observation of biochemical serum parameters or histopathology of examined tissues revealed no adverse effects of HB either after the administration of single dose lower than 35 mg/kg or following repeated administration at 10 mg/kg. These dosages should be further considered for potential therapeutic applications.

The Utility of Novel Urinary Biomarkers in Mice for Drug Development Studies

Novel urinary protein biomarkers have recently been identified and qualified in rats for the early detection of renal injury in drug development studies. However, there are few reports on the utility of these renal biomarkers in mice, another important and widely used preclinical animal species for drug development studies. The purpose of this study was to assess the value of these recently qualified biomarkers for the early detection of drug-induced kidney injury (DIKI) in different strains of mice using multiple assay panels. To this end, we evaluated biomarker response to kidney injury induced by several nephrotoxic agents including amphotericin B, compound X, and compound Y. Several of the biomarkers were shown to be sensitive to DIKI in mice. When measured, urinary albumin and neutrophil gelatinase-associated lipocalin were highly sensitive to renal tubular injury, regardless of the assay platforms, mouse strain, and nephrotoxic agents. Depending on the type of renal tubular injury, kidney injury molecule-1 was also highly sensitive, regardless of the assay platforms and mouse strain. Osteopontin and cystatin C were modestly to highly sensitive to renal tubular injury, but the assay type and/or the mouse strain should be considered before using these biomarkers. Calbindin D28 was highly sensitive to injury to the distal nephron in mice. To our knowledge, this is the first report that demonstrates the utility of novel urinary biomarkers evaluated across multiple assay platforms and nephrotoxicants in different mice strains with DIKI. These results will help drug developers make informed decisions when selecting urinary biomarkers for monitoring DIKI in mice for toxicology studies.

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.

Urinary Proteomics Identifying Novel Biomarkers for the Diagnosis of Adult-Onset Still's Disease

Adult-onset Still’s disease (AOSD) is a systemic, multigenic autoinflammatory disease, and the diagnosis of AOSD must rule out neoplasms, infections, and other autoimmune diseases. Development of a rapid and efficient but non-invasive diagnosis method is urgently needed for improving AOSD therapy. In this study, we first performed a urinary proteomic study using isobaric tags for relative and absolute quantification (iTRAQ) labeling combined with liquid chromatography–tandem mass spectrometry analysis in patients with AOSD and healthy control (HC) subjects. The urinary proteins were enriched in pathways of the innate immune system and neutrophil degranulation, and we identified that the α-1-acid glycoprotein 1 (LRG1), orosomucoid 1 (ORM1), and ORM2 proteins were highly expressed in patients with AOSD. The elevated urine levels of LRG1, ORM1, and ORM2 were further validated by enzyme-linked immunosorbent assay in active patients with AOSD, disease controls, and HC subjects. Receiver operating characteristic curves showed that the areas under the curve of LRG1, ORM1, and ORM2 were 0.700, 0.837, and 0.736, respectively (all p < 0.05). Furthermore, we found that the urine levels of LRG1, ORM1, and ORM2 were positively correlated with the systemic score and erythrocyte sedimentation rate and that the urine levels of LRG1 were positively correlated with interleukin 1β (IL-1β), IL-6, and IL-18 levels, whereas the urine levels of ORM1 were positively correlated with the IL-1β level. Together, our study identified novel urinary markers for non-invasive and simple screening of AOSD.

Slower Elimination of Tofacitinib in Acute Renal Failure Rat Models: Contribution of Hepatic Metabolism and Renal Excretion

Tofacitinib is a Jak inhibitor developed as a treatment for rheumatoid arthritis. Tofacitinib is metabolized mainly through hepatic CYP3A1/2, followed by CYP2C11. Rheumatoid arthritis tends to increase renal toxicity due to drugs used for long-term treatment. In this study, pharmacokinetic changes of tofacitinib were evaluated in rats with gentamicin (G-ARF) and cisplatin-induced acute renal failure (C-ARF). The time-averaged total body clearance (CL) of tofacitinib in G-ARF and C-ARF rats after 1-min intravenous infusion of 10 mg/kg was significantly decreased by 37.7 and 62.3%, respectively, compared to in control rats. This seems to be because the time-averaged renal clearance (CL_R) was significantly lower by 69.5 and 98.6%, respectively, due to decreased creatinine clearance (CL_CR). In addition, the time-averaged nonrenal clearance (CL_NR) was also significantly lower by 33.2 and 57.4%, respectively, due to reduction in the hepatic CYP3A1/2 and CYP2C11 subfamily in G-ARF and C-ARF rats. After oral administration of tofacitinib (20 mg/kg) to G-ARF and C-ARF rats, both CL_R and CL_NR were also significantly decreased. In conclusion, an increase in area under plasma concentration-time curves from time zero to time infinity (AUC) of tofacitinib in G-ARF and C-ARF rats was due to the significantly slower elimination of tofacitinib contributed by slower hepatic metabolism and urinary excretion of the drug.

Translational Safety Biomarkers of Kidney Injury

Acute kidney injury continues to be a common problem and there continues to be a medical need for sensitive translational biomarkers for clinical monitoring. The past decade has yielded unprecedented progress in fundamental research into novel kidney biomarker evaluation and the mechanistic understanding of kidney injury; as such, these novel biomarkers increasingly are being used in preclinical drug development and in early clinical trials of drug candidates on a case-by-case basis, as well as in medical and veterinary practice. With the recent successful clinical qualification of a subset of novel accessible biomarker candidates for use in early phase clinical trials, continued clinical evaluation may enable expanded regulatory qualification for more generalized clinical use. This review provides a comprehensive overview about the discovery and development of kidney safety biomarkers with a focus on current progress in nonclinical research, progress toward translation to the clinic, and perspectives on future opportunities.

Kidney-based in vitro models for drug-induced toxicity testing

The kidney is frequently involved in adverse effects caused by exposure to foreign compounds, including drugs. An early prediction of those effects is crucial for allowing novel, safe drugs entering the market. Yet, in current pharmacotherapy, drug-induced nephrotoxicity accounts for up to 25% of the reported serious adverse effects, of which one-third is attributed to antimicrobials use. Adverse drug effects can be due to direct toxicity, for instance as a result of kidney-specific determinants, or indirectly by, e.g., vascular effects or crystals deposition. Currently used in vitro assays do not adequately predict in vivo observed effects, predominantly due to an inadequate preservation of the organs' microenvironment in the models applied. The kidney is highly complex, composed of a filter unit and a tubular segment, together containing over 20 different cell types. The tubular epithelium is highly polarized, and the maintenance of this polarity is critical for optimal functioning and response to environmental signals. Cell polarity is dependent on communication between cells, which includes paracrine and autocrine signals, as well as biomechanic and chemotactic processes. These processes all influence kidney cell proliferation, migration, and differentiation. For drug disposition studies, this microenvironment is essential for prediction of toxic responses. This review provides an overview of drug-induced injuries to the kidney, details on relevant and translational biomarkers, and advances in 3D cultures of human renal cells, including organoids and kidney-on-a-chip platforms.

Molecular optical imaging probes for early diagnosis of drug-induced acute kidney injury

Drug-induced acute kidney injury (AKI) with a high morbidity and mortality is poorly diagnosed in hospitals and deficiently evaluated in drug discovery. Here, we report the development of molecular renal probes (MRPs) with high renal clearance efficiency for in vivo optical imaging of drug-induced AKI. MRPs specifically activate their near-infrared fluorescence or chemiluminescence signals towards the prodromal biomarkers of AKI including the superoxide anion, N-acetyl-β-D-glucosaminidase and caspase-3, enabling an example of longitudinal imaging of multiple molecular events in the kidneys of living mice. Importantly, they in situ report the sequential occurrence of oxidative stress, lysosomal damage and cellular apoptosis, which precedes clinical manifestation of AKI (decreased glomerular filtration). Such an active imaging mechanism allows MRPs to non-invasively detect the onset of cisplatin-induced AKI at least 36 h earlier than the existing imaging methods. MRPs can also act as exogenous tracers for optical urinalysis that outperforms typical clinical/preclinical assays, demonstrating their clinical promise for early diagnosis of AKI.

Influence of Storage Conditions and Preservatives on Metabolite Fingerprints in Urine

Human urine, which is rich in metabolites, provides valuable approaches for biomarker measurement. Maintaining the stability of metabolites in urine is critical for accurate and reliable research results and subsequent interpretation. In this study, the effect of storage temperature (4, 22, and 40 °C), storage time (24 and 48 h), and use of preservatives (boric acid (BA), thymol) and para-aminobenzoic acid (PABA) on urinary metabolites in the pooled urine samples from 20 participants was systematically investigated using large-scale targeted liquid chromatography tandem mass spectrometry (LC-MS/MS)-based metabolomics. Statistical analysis of 158 reliably detected metabolites showed that metabolites in urine with no preservative remained stable at 4 °C for 24 and 48 h as well as at 22 °C for 24 h, but significant metabolite differences were observed in urine stored at 22 °C for 48 h and at 40 °C. The mere addition of BA caused metabolite changes. Thymol was observed to be effective in maintaining metabolite stability in urine in all the conditions designed, most likely due to the inhibitory effect of thymol on urine microbiota. Our results provide valuable urine preservation guidance during sample storage, which is essential for obtaining reliable, accurate, and reproducible analytical results from urine samples.

Comparative Performance of Urinary Biomarkers for Vancomycin-Induced Kidney Injury According to Timeline of Injury

Urinary biomarkers are superior to serum creatinine for defining onset and extent of kidney injury. This study classifies the temporal predictive ability of biomarkers for vancomycin-induced kidney injury (VIKI) as defined by histopathologic damage. Male Sprague-Dawley rats (n = 125) were randomized to receive 150 to 400 mg/kg of body weight/day vancomycin via once or twice daily intraperitoneal injection over 1, 3, or 6 days. Urine was collected once during the 24 h prior to euthanasia or twice for rats treated for 6 days. Receiver operating characteristic (ROC) curves were employed to assess the urinary biomarker performances of kidney injury molecule 1 (KIM-1), clusterin, osteopontin (OPN), cystatin C, and neutrophil gelatinase-associated lipocalin (NGAL) to predict histopathologically defined VIKI (using a national standard pathological assessment scheme from hematoxylin and eosin stained kidneys). Urinary KIM-1, clusterin, and OPN outperformed cystatin C and NGAL with regard to sensitivity and specificity. For the earliest injury, urinary KIM-1 (area under the receiver operating characteristic curve [AUC], 0.662; P < 0.001) and clusterin (AUC, 0.706; P < 0.001) were the most sensitive for predicting even low-level histopathologic damage at 24 h compared to NGAL. KIM-1 and clusterin are the earliest and most sensitive predictors of VIKI. As injury progresses, KIM-1, clusterin, and OPN best define the extent of damage.

CXCL8(3-72) K11R/G31P protects against sepsis-induced acute kidney injury via NF-κB and JAK2/STAT3 pathway

Background

Acute kidney injury (AKI), which is mainly caused by sepsis, has high morbidity and mortality rates. CXCL8_(3–72) K11R/G31P (G31P) can exert therapeutic effect on inflammatory diseases and malignancies. We aimed to investigate the effect and mechanism of G31P on septic AKI.

Methods

An AKI mouse model was established, and kidney injury was assessed by histological analysis. The contents of serum creatinine (SCr) and blood urea nitrogen (BUN) were measured by commercial kits, whereas neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) were detected by enzyme-linked immunosorbent assay (ELISA) kits. The expressions of CXCL8 in serum and kidney tissues were determined using ELISA and immunohistochemical analysis, respectively. Apoptosis rate of renal tissue was detected by terminal deoxynucleotidyl transfer-mediated dUTP nick end labeling (TUNEL) analysis. The expressions of inflammatory cytokines were measured by quantitative real-time PCR and Western blot, respectively. The apoptosis-related proteins, JAK2, STAT3, NF-κB and IκB were determined by Western blot.

Results

G31P could reduce the levels of SCr, BUN, HGAL and KIM-1 and inhibit the renal tissue injury in AKI mice. G31P was also found to suppress the serum and nephric CXCL8 expressions and attenuated the apoptosis rate. The levels of inflammatory cytokines, pro-apoptotic proteins were decreased, while the anti-apoptotic proteins were increased by G31P in AKI mice. G31P also inhibited the activation of JAK2, STAT3 and NF-κB in AKI mice.

Conclusion

These results suggest that G31P could protect renal function and attenuate the septic AKI. Our findings provide a potential target for the treatment of AKI.

Clinical Efficacy of Spectral Computed Tomography for Evaluating Liver Function in Patients with Budd-Chiari Syndrome

RATIONALE AND OBJECTIVES

To analyze the clinical relevance of quantitative spectral parameters in evaluating the treatment of patients with Budd-Chiari syndrome (BCS) with different classes of liver function by comparing normalized iodine concentration (NIC) before and after BCS treatment.

MATERIALS AND METHODS

Angiographic data were obtained from 41 patients with confirmed BCS between December 2015 and March 2017. All patients underwent spectral computed tomography (CT) before and after BCS treatment; the average interval between scans was 2-4 months. Iodine concentration and NIC were measured and calculated during the portal venous phase in liver segments I-VIII. Clinical liver function parameters including prothrombin time (PT), albumin (ALB), total bilirubin (TBIL), aspartate aminotransferase, and alanineaminotransferase were recorded. Liver function was classified according to the Child-Pugh grading standard (before treatment). Liver NIC and liver function-related parameters before and after treatment were compared using the paired t-test; Pearson correlation analysiswas performed to analyze the aforementioned parameters among different liver function classes before BCS treatment. p < 0.05 was to be statistically considered significant.

RESULTS

PT and TBIL were negatively correlated with liver NIC (p < 0.05), whereas ALB and liver NIC exhibited a positive correlation (p < 0.05). Comparison of NIC before and after treatment revealed that NIC in liver segments I-VIII was higher after treatment. The p values for segments II-VIII were 0.041, 0.046, 0.041, 0.038, 0.039, 0.042, and 0.040, respectively; the differences were statistically significant (p < 0.05). The increase in NIC in liver segments I-VIII before and after treatment was more significant in patients with class C liver function than in their class B and A counterparts. Comparison of liver function-related parameters revealed that PT was shortened after treatment; ALB levels were increased; and TBIL, alanine aminotransferase, and aspartate aminotransferase levels were decreased.

CONCLUSION

NIC determined through spectral CT was beneficial for evaluating liver function in patients with BCS, and can provide imaging data for reexamination, prognostic evaluation, and follow-up of patients with BCS after treatment. Liver parenchyma NIC values in BCS patients with varying liver function may provide a degree of diagnostic value. Multi-locus and multi-parameter studies of spectral CT can help to further evaluate liver function and assess prognosis in patients with BCS.

Tenofovir disoproxil fumarate initiation and changes in urinary biomarker concentrations among HIV-infected men and women

OBJECTIVES

Urinary biomarkers of kidney injury may have potential to identify subclinical injury attributable to tenofovir disoproxil fumarate (TDF) toxicity.

DESIGN

This observational study included 198 HIV-infected participants from the Multicenter AIDS Cohort Study and the Women's Interagency HIV Study, who initiated TDF between 2009 and 2015 and had urine samples collected at baseline before and after TDF initiation.

METHODS

We used linear mixed-effects models controlling for urine creatinine and time on TDF to evaluate the effects of TDF initiation on changes in 14 urinary biomarkers.

RESULTS

Within 1 year after TDF initiation, concentrations of trefoil factor 3 [+78%; 95% confidence interval (CI) +38%, +129%), alpha-1 microglobulin (α1m) (+32%; 95% CI +13%, +55%), clusterin (+21%; 95% CI +6%, +38%), uromodulin (+19%; 95% CI +4%, +36%), and kidney injury molecule-1 (KIM-1) (+13%; 95% CI +1%, +26%) significantly increased, whereas interleukin-18 (IL-18) significantly decreased (-13%, 95% CI -7%, -25%). Subsequent to the first year of TDF use, biomarker concentrations stabilized, and these changes were not statistically significant. When stratifying by baseline viremia (HIV-1 RNA < vs. ≥80 copies/ml), concentration changes for most biomarkers during the first year of TDF use were greater among aviremic vs. viremic participants, with significant differences in α1m (+80 vs. +22%), KIM-1 (+43 vs. +10%), beta-2 microglobulin (+83 vs. -10%), YKL-40 (+33 vs. -5%), and IL-18 (+20 vs. -27%).

CONCLUSIONS

TDF initiation was associated with substantial changes in urinary biomarkers of kidney injury within the first year of use, particularly among aviremic participants. A urinary biomarker panel may be a clinically useful tool to detect and monitor the heterogeneous effects of TDF on the kidney.

Changes in novel gastrointestinal and renal injury markers in the blood plasma of sheep following increasing intravenous doses of tolfenamic acid

The administration of high doses of non-steroidal anti-inflammatory drugs (NSAID), such as tolfenamic acid (TA), has undesirable effects on different organs. Some novel biomarkers have been reported that can determine the gastrointestinal and renal injury caused by a high dose of NSAIDs or other toxic substances. This study was aimed at determining the changes in gastrointestinal (TFF2 and HYP), renal (NGAL and KIM-1) and cardiac (cTn-I, CK-MB) injury markers after the use of increasing intravenous doses of TA in sheep. TA was administered intravenously to groups of six sheep each, at the dose levels of 0 (Group 0, i.e., G0), 2 (G2), 4 (G4), 8 (G8) and 16 (G16) mg/kg. The concentrations of the studied biomarkers were measured at 3, 9, 18 and 36 h after administration of TA. The TFF2 and NGAL concentrations in G16 were found to be significantly higher (P < 0.05) than in the other groups except for G8 at different sampling times. HYP concentration in G16 was observed to be significantly (P < 0.05) lower than that in all other groups at 36 h. KIM-1 level in G16 was significantly (P < 0.05) higher than in all other groups at different sampling times. An increase in the renal markers, KIM-1 and NGAL, in G8 was observed before any change in plasma creatinine and urea. The cardiac marker cTn-I in G16 was significantly (P < 0.05) higher than in other groups at different sampling times. The results showed that the novel biomarkers (HYP, TFF2, NGAL, and KIM-1) can be used to determine gastric and renal injury in sheep.

Investigating the Value of Urine Volume, Creatinine, and Cystatin C for Urinary Biomarkers Normalization for Drug Development Studies

Novel urinary protein biomarkers have recently been identified and qualified in rats for the early detection of renal injury in drug development studies. However, there seems to be no standardized normalization method for analyzing these urinary biomarkers, as some users normalize with urinary creatinine (uCr), urine volume (uVol), or leave biomarker un-normalized. More recently, urinary cystatin C is also emerging as a urinary biomarker normalizer, given some of its characteristics as a glomerular filtration marker. The purpose of this study was to identify an optimal drug-induced kidney injury biomarker normalization method that can be adopted more uniformly in the field. To this end, we compared the variability of uVol, urinary cystatin C, and Cr in healthy rats; we evaluated the sensitivity of the renal biomarkers to renal injury after normalization with uVol, uCr, and cystatin C in rats with cisplatin-induced renal injury. We showed that, over time, uCr was less variable than urinary cystatin C and uVol. When the renal biomarkers were normalized with the 3 normalizing end points, the biomarkers showed (1) least variability following normalization with Cr in healthy animals and (2) poor sensitivity when normalized with urinary cystatin C in animals with renal injury. Overall, the results suggested that uCr is better than urinary cystatin C and uVol for normalizing renal biomarkers in rats under controlled preclinical conditions. To our knowledge, this is the first report that compared the variability of uVol, cystatin C, and Cr in the context of renal biomarkers' normalization.

Urinary proteome analysis of acute hypercoagulable state in rat model induced by ε-aminocaproic acid

The hypercoagulable state occurs in a group of prothrombotic disorders associated with an increased risk for thromboembolic events, but it is difficult to diagnose due to the lack of available biomarkers. This study aimed to investigate systematic changes of urinary proteome in acute hypercoagulable state induced by certain antifibrinolytics. To reduce the effects of both genetic and environmental factors on the urinary proteome, we used a rat model of acute hypercoagulable state induced by an antifibrinolytic agent ε-aminocaproic acid, resembling human hypercoagulable state. Urine samples were collected during acute hypercoagulable state for analysis by liquid chromatography-tandem mass spectrometry (LCMS/MS). Of 65 significantly changed proteins in acute hypercoagulable state, 38 proteins had human orthologs, and 18 proteins were identified as stable in normal human urine. None of the identified proteins have been found to be clotting factors, but 4 proteins are known to be involved in the regulation of blood coagulation factors. Two proteins were verified as the markers associated with acute hypercoagulable state by Western blot analysis. In addition, four common differential urinary proteins have been found in acute hypercoagulable state induced by another antifibrinolytics tranexamic acid. These four proteins are potential biomarkers for early diagnosis of hypercoagulable state to prevent the development of thrombotic diseases.

Gentamicin induced acute renal damage and its evaluation using urinary biomarkers in rats

•

Gentamicin induced dose dependent and temporal change in urinary biomarkers.

•

Histological changes were minimal to severe on Day 4 & 8 respectively at both doses.

•

Several fold increase in urinary biomarkers on Day 4 and 8 at both doses.

•

On Day 8, increase in urinary and serum markers and histological changes.

•

Clusterin is highly sensitive urinary biomarkers.

Consistent, sensitive biomarkers of acute kidney injury in animal models and humans have historically represented a poorly met need for investigators and clinicians. Detection of early kidney damage using urinary biomarkers is essential to assess the adversity in preclinical toxicology studies, which will help in reducing attrition of lead candidates in drug development. This study was undertaken to evaluate recently identified urinary biomarkers use in identifying acute kidney injury compared to traditional serum markers in experimentally induced nephrotoxicity in male Sprague Dawley (SD) rats. Gentamicin induced nephrotoxicity in Sprague Dawley rats is commonly detected using serum markers and histological evaluation of kidneys. Gentamicin, an aminoglycoside was administered at 30 and 100 mg/kg/day dose (subcutaneous) for seven consecutive days to induce nephrotoxicity. On day 4 and day 8 post treatment, serum and urine samples from these rats were analyzed for traditional serum/urine and novel urinary biomarkers and microscopic evaluation of kidneys.

On Day 4, no statistically significant change in serum BUN and creatinine level, but increase in urinary microalbumin (mALB) and urinary protein (UP) noticed in both doses of Gentamicin treated rats. On Day 8 significant increase in serum blood urea nitrogen (BUN), serum creatinine, UP and urinary mALB at 100 mg/kg/day, increase in total protein and decrease in albumin in 30 and 100 mg/kg/day and decrease in BUN and creatinine at 100 mg/kg of Gentamicin treated rats. The BUN and creatinine levels or fold change was comparable between control and 30 mg/kg of Gentamicin on Day 8, however, there was 5.6 and 3.4 fold change in BUN and Creatinine level noticed at 100 mg/kg/day of Gentamicin. On Day 4 and 8, significant increase in urinary levels of Clusterin was noted with animals administered both doses of Gentamicin. Similarly, significant increase in urinary levels of kidney injury molecule 1 (Kim-1), Cystatin C and neutrophil gelatinase-associated lipocalin (NGAL) were noticed with animals administered Gentamicin at 100 mg/kg/day on both Day 4 and 8. All these markers have shown dose-dependent change.

Histological changes seen on Day 4 and Day 8 were of minimal to mild and moderate to severe in nature at both doses, respectively. The results demonstrated the sensitiveness and accuracy of detecting acute renal damage with novel urinary biomarkers, and their use in diagnosing early kidney damage. This helps in adversity assessment in animal toxicology studies and advocating right treatment to patients who have early renal injury which otherwise can only be diagnosed by elevated levels of traditional biomarkers in blood only after >30% of kidneys is damaged.

Proteomics for Biomarker Identification and Clinical Application in Kidney Disease

Treatment effectiveness for kidney disease is limited by lack of accuracy, sensitivity, specificity of diagnostic, prognostic, and therapeutic biomarkers. The gold standard test renal biopsy along with serum creatinine and proteinuria is often necessary to establish a diagnosis, particularly in glomerular disease. Proteomics has become a powerful tool for novel biomarker discovery in kidney disease. Novel proteomics offer earlier and more accurate diagnosis of renal pathology than possible with traditional biomarkers such as serum creatinine and urine protein. In addition, proteomic biomarkers could also be useful to choose the most suitable therapeutic targets. This review focuses on the current status of proteomic biomarkers from animal models (5/6 nephrectomy, unilateral ureteral obstruction, and diabetic nephropathy) and human studies (chronic kidney disease, glomerular diseases, transplantation, dialysis, acute and drug-induced kidney injury) to assess relevant findings and clinical usefulness. Current issues and problems related to the discovery, validation, and clinical application of proteomic biomarkers are discussed. We also describe several proteomic strategies highlighting technologic advancements, specimen selection, data processing and analysis. This review might provide help in future proteomic studies to improve the diagnosis and management of kidney disease.

A Proposed Computed Tomography Contrast Agent Using Carboxybetaine Zwitterionic Tantalum Oxide Nanoparticles: Imaging, Biological, and Physicochemical Performance

OBJECTIVES

The aim of this study was to produce and evaluate a proposed computed tomography (CT) contrast agent based on carboxybetaine zwitterionic (CZ)-coated soluble tantalum oxide (TaO) nanoparticles (NPs). We chose tantalum to provide superior imaging performance compared with current iodine-based clinical CT contrast agents. We developed the CZ coating to provide biological and physical performance similar to that of current iodinated contrast agents. In addition, the aim of this study was to evaluate the imaging, biological, and physicochemical performance of this proposed contrast agent compared with clinically used iodinated agents.

MATERIALS AND METHODS

We evaluated CT imaging performance of our CZ-TaO NPs compared with that of an iodinated agent in live rats, imaged centrally located within a tissue-equivalent plastic phantom that simulated a large patient. To evaluate vascular contrast enhancement, we scanned the rats' great vessels at high temporal resolution during and after contrast agent injection. We performed several in vivo CZ-TaO NP studies in healthy rats to evaluate tolerability. These studies included injecting the agent at the anticipated clinical dose (ACD) and at 3 times and 6 times the ACD, followed by longitudinal hematology to assess impact to blood cells and organ function (from 4 hours to 1 week). Kidney histological analysis was performed 48 hours after injection at 3 times the ACD. We measured the elimination half-life of CZ-TaO NPs from blood, and we monitored acute kidney injury biomarkers with a kidney injury assay using urine collected from 4 hours to 1 week. We measured tantalum retention in individual organs and in the whole carcass 48 hours after injection at ACD. Carboxybetaine zwitterionic TaO NPs were synthesized and analyzed in detail. We used multidimensional nuclear magnetic resonance to determine surface functionality of the NPs. We measured NP size and solution properties (osmolality and viscosity) of the agent over a range of tantalum concentrations, including the high concentrations required for standard clinical CT imaging.

RESULTS

Computed tomography imaging studies demonstrated image contrast improvement of approximately 40% to 50% using CZ-TaO NPs compared with an iodinated agent injected at the same mass concentration. Blood and organ analyses showed no adverse effects after injection in healthy naive rats at 3 times the ACD. Retention of tantalum at 48 hours after injection was less than 2% of the injected dose in the whole carcass, which very closely matched the reported retention of existing commercial iodine-based contrast agents. Urine analysis of sensitive markers for acute kidney injury showed no responses at 1 week after injection at 3 times the ACD; however, a moderate response in the neutrophil gelatinase-associated lipocalin biomarker was measured at 24 and 48 hours. Compared with other TaO NPs reported in the literature, CZ-TaO NPs had relatively low osmolality and viscosity at concentrations greater than 200 mg Ta/mL and were similar in these physical properties to dimeric iodine-based contrast agents.

CONCLUSIONS

We found that a CZ-TaO NP-based contrast agent is potentially viable for general-purpose clinical CT imaging. Our results suggest that such an agent can be formulated with clinically viable physicochemical properties, can be biologically safe and cleared rapidly in urine, and can provide substantially improved image contrast at CT compared with current iodinated agents.

Salt Selection Matters: Differential Renal Toxicity With MDV1634.Maleate Versus MDV1634.2HCl

Salt forms of pharmaceutical compounds can have unique pharmacokinetic and toxicity properties. MDV1634 was evaluated for neurology indication and also demonstrated blood pressure (BP)-lowering effects in nonclinical studies. During the chemistry manufacturing campaign, 2 salt forms, dihydrochloride (2HCl) and maleate (MAL), which improved chemical stability and water solubility of the free base were identified. MDV1634.MAL showed better chemical attributes and was evaluated in toxicology studies for further development. A 28-day oral toxicity study in dogs with MDV1634.MAL demonstrated partially reversible renal toxicity. Although MAL salt is generally regarded as safe, renal toxicity is sometimes observed in rats and dogs. To evaluate contribution of each salt form to renal toxicity and BP lowering, an additional 28-day study was conducted with MDV1634.2HCL and MDV1634.MAL, which included toxicokinetics, continuous BP measurement in a subset of dogs, and sensitive urinary biomarker evaluation for temporal monitorability and reversibility of potential renal findings. In the repeat study, both salt forms showed similar exposures during the dosing period, but renal tubular toxicity was observed only with MDV1634.MAL and not with MDV1634.2HCl. The renal findings with MDV1634.MAL included early urinary biomarker changes (increase in albumin, clusterin, β2 microglobulin, and neutrophil gelatinase-associated lipocalin); elevations in serum blood urea nitrogen and creatinine; and microscopic findings of partially reversible tubular basophilia, single cell necrosis, pigmentation, and mineralization. The renal findings in contrast to the BP findings were MAL-specific and considered not related to MDV1634, thereby under scoring the importance of salt forms in pharmaceutical development.

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.

Sex differences in renal transcriptome and programmed hypertension in offspring exposed to prenatal dexamethasone

Glucocorticoids, predominantly dexamethasone (DEX), are widely used to reduce the risk of prematurity-related chronic lung disease. However, prenatal DEX treatment links to adverse effects in later life, including hypertension. Given that sex differences exist in the blood pressure (BP) control, and that renal transcriptome is sex-specific, thus we intended to elucidate whether prenatal DEX-induced programmed hypertension is in a sex-specific manner and identify candidate genes and pathways using the whole-genome RNA next-generation sequencing (NGS) approach. Offspring were assigned to 4 groups (n=7-8/group): male control (MC), female control (FC), male DEX (MD), and female DEX (FD). Dexamethasone (0.1mg/kg body weight) or vehicle was intraperitoneally administered to pregnant SD rats from gestational day 16-22, to construct a DEX model. Rats were killed at 16weeks of age. Prenatal DEX induced sex-specific increase in BPs in male but not female adult offspring. Prenatal DEX elicited renal programming in a sex-specific fashion as demonstrated by 8 and 18 DEGs in male and female offspring, respectively. Among them, two genes, Hbb and Hba-a2, were shared. The resistance of female offspring to prenatal DEX-induced programmed hypertension is related to a lower Agt expression. Prenatal DEX induced programmed hypertension in adult male but not female offspring, which was related to renal programming affecting sex-biased genes and the RAS. Early identification of sex-specific underlying mechanisms could provide novel deprogramming strategy to reach maximal optimization in both sexes.

Evaluation of Vancomycin Exposures Associated with Elevations in Novel Urinary Biomarkers of Acute Kidney Injury in Vancomycin-Treated Rats

Vancomycin has been associated with acute kidney injury (AKI). However, the pharmacokinetic/toxicodynamic relationship for AKI is not well defined. Allometrically scaled vancomycin exposures were used to assess the relationship between vancomycin exposure and AKI. Male Sprague-Dawley rats received clinical-grade vancomycin in normal saline (NS) as intraperitoneal (i.p.) injections for 24- to 72-h durations with doses ranging 0 to 200 mg/kg of body weight divided once or twice daily. Urine was collected over the protocol's final 24 h. Renal histopathology was qualitatively scored. Urinary biomarkers (e.g., cystatin C, clusterin, kidney injury molecule 1 [KIM-1], osteopontin, lipocalin 2/neutrophil gelatinase-associated lipocalin 2) were assayed using a Luminex xMAP system. Plasma vancomycin concentrations were assayed by high-performance liquid chromatography with UV detection. A three-compartment vancomycin pharmacokinetic model was fit to the data with the Pmetrics package for R. The exposure-response in the first 24 h was evaluated using Spearman's nonparametric correlation coefficient (rs) values for the area under the concentration-time curve during the first 24 h (AUC0-24), the maximum concentration in plasma during the first 24 h (Cmax0-24 ), and the lowest (minimum) concentration in plasma after the dose closest to 24 h (Cmin0-24 ). A total of 52 rats received vancomycin (n = 42) or NS (n = 10). The strongest exposure-response correlations were observed between AUC0-24 and Cmax0-24 and urinary AKI biomarkers. Exposure-response correlations (rs values) for AUC0-24, Cmax0-24 , and Cmin0-24 were 0.37, 0.39, and 0.22, respectively, for clusterin; 0.42, 0.45, and 0.26, respectively, for KIM-1; and 0.52, 0.55, and 0.42, respectively, for osteopontin. However, no differences in histopathological scores were observed. Optimal sampling times after administration of the i.p. dose were 0.25, 0.75, 2.75, and 8 h for the once-daily dosing schemes and 0.25, 1.25, 14.5, and 17.25 h for the twice-daily dosing schemes. Our observations suggest that AUC0-24 or Cmax0-24 correlates with increases in urinary AKI biomarkers.

Identification of urinary microRNA biomarkers for detection of gentamicin-induced acute kidney injury in rats

MicroRNAs (miRNAs) have been recently recognized as promising non-invasive biomarkers for detecting the organ injuries. To further understand the sensibility and reliability of miRNA measurements in urine sample for predicting drug-induced early nephrotoxicity, a global urinary miRNA expression analysis was performed in the rodent models with gentamicin-induced acute kidney injury (AKI). Male Wistar rats were daily administrated with gentamicin (0, 60, and 120 mg/kg) for up to 10 days by intraperitoneal injection, and the miRNA profiling of animal urine samples were subsequently analyzed using TaqMan(®) Array Rodent miRNA Cards. The results showed that four miRNAs (mmu-miR-138-5p, mmu-miR-1971, mmu-miR-218-1-3p, and rno-miR-489) were continuously increased in urine samples since day 4 after administration with gentamicin, which was not reflected by the standard markers such as serum creatinine (Cr) and urea nitrogen (BUN). Furthermore, other nine urinary miRNAs were increased in both 60 and 120 mg/kg groups on day 8. Receiver operator characteristics analysis demonstrated that the performance of these miRNAs with time- or dose-dependent increases were comparable to standard biomarkers (i.e. serum Cr and BUN), suggesting that the urinary miRNA panel can be used as potential biomarkers for the detection of gentamicin-induced AKI in rats. Moreover, the computer prediction analysis showed that these differentially expressed miRNAs were potentially targeted to many genes, which were mainly associated with the regulation of metabolic process and signaling. These data will improve the understanding and prediction of toxicology processes induced by nephrotoxicants.

Pharmacokinetic profile that reduces nephrotoxicity of gentamicin in a perfused kidney-on-a-chip

Nephrotoxicity is often underestimated because renal clearance in animals is higher compared to in humans. This paper aims to illustrate the potential to fill in such pharmacokinetic gaps between animals and humans using a microfluidic kidney model. As an initial demonstration, we compare nephrotoxicity of a drug, administered at the same total dosage, but using different pharmacokinetic regimens. Kidney epithelial cell, cultured under physiological shear stress conditions, are exposed to gentamicin using regimens that mimic the pharmacokinetics of bolus injection or continuous infusion in humans. The perfusion culture utilized is important both for controlling drug exposure and for providing cells with physiological shear stress (1.0 dyn cm(-2)). Compared to static cultures, perfusion culture improves epithelial barrier function. We tested two drug treatment regimens that give the same gentamycin dose over a 24 h period. In one regimen, we mimicked drug clearance profiles for human bolus injection by starting cell exposure at 19.2 mM of gentamicin and reducing the dosage level by half every 2 h over a 24 h period. In the other regimen, we continuously infused gentamicin (3 mM for 24 h). Although junctional protein immunoreactivity was decreased with both regimens, ZO-1 and occludin fluorescence decreased less with the bolus injection mimicking regimen. The bolus injection mimicking regimen also led to less cytotoxicity and allowed the epithelium to maintain low permeability, while continuous infusion led to an increase in cytotoxicity and permeability. These data show that gentamicin disrupts cell-cell junctions, increases membrane permeability, and decreases cell viability particularly with prolonged low-level exposure. Importantly a bolus injection mimicking regimen alleviates much of the nephrotoxicity compared to the continuous infused regimen. In addition to potential relevance to clinical gentamicin administration regimens, the results are important in demonstrating the general potential of using microfluidic cell culture models for pharmacokinetics and toxicity studies.

A porphyrin-PEG polymer with rapid renal clearance

Tetracarboxylic porphyrins and polyethylene glycol (PEG) diamines were crosslinked in conditions that gave rise to a water-soluble porphyrin polyamide. Using PEG linkers 2 kDa or larger prevented fluorescence self-quenching. This networked porphyrin mesh was retained during dialysis with membranes with a 100 kDa pore size, yet passed through the membrane when centrifugal filtration was applied. Following intravenous administration, the porphyrin mesh, but not the free porphyrin, was rapidly cleared via renal excretion. The process could be monitored by fluorescence analysis of collected urine, with minimal background due to the large Stokes shift of the porphyrin (230 nm separating excitation and emission peaks). In a rhabdomyolysis mouse model of renal failure, porphyrin mesh urinary clearance was significantly impaired. This led to slower accumulation in the bladder, which could be visualized non-invasively via fluorescence imaging. Without further modification, the porphyrin mesh was chelated with (64)Cu for dynamic whole body positron emission tomography imaging of renal clearance. Together, these data show that small porphyrin-PEG polymers can serve as effective multimodal markers of renal function.

Hand-assisted Laparoscopic Donor Nephrectomy and Cytokine Changes

BACKGROUND

Laparoscopic living-donor nephrectomy (LDN) exerts systemic effects causing transaminitis and increased urinary neutrophil gelatinase-associated lipocalm (NGAL) excretion. Hand-assisted laparoscopic donor nephrectomy, which tends to be shorter with less pneumoperitoneum, may be hypothesized to produce less systemic stimulation than total laparoscopic LDN.

METHODS

Serial urine and serum samples were collected from 15 patients undergoing HALDN. Samples were analyzed for NGAL and kidney injury molecule 1 (KIM-1) levels preoperatively and 24 hours post-surgery. Data relating to alanine aminotransferase, creatinine, and estimated glomerular filtration rate was also analyzed in 48 live donors preoperatively and at 24 hours and 48 hours post-surgery and compared to published data on LDN.

RESULTS

Expected changes to creatinine and estimated glomerular filtration rates were observed in the donors. Compared to the preoperative levels, alanine aminotransferase levels showed a significant decrease at 24 hours (P = .004) and were not significantly different from baseline levels at 48 hours (P = .08). Serum KIM-1 and NGAL levels remained unchanged (P = .89 and P = .14, respectively) at 24 hours after donation. Similarly, urinary levels of KIM-1 and NGAL were not statistically significantly different after donation. Mean operating time for this cohort was 1 hour, 36 minutes.

CONCLUSIONS

In contrast to other published data, our cohort did not exhibit changes to liver function tests or biomarker changes after donor nephrectomy. This could be because of the lower operative time (96 minutes vs. 216 minutes) or because of the intermittent release of the pneumoperitoneum in the hand-assisted method which may exert less of a systemic inflammatory response.

Comparison of changes in urinary and blood levels of biomarkers associated with proximal tubular injury in rat models

To investigate useful biomarkers associated with proximal tubular injury, we assessed changes in levels of a focused set of biomarkers in urine and blood. Male rats administered a single dose or four doses of gentamicin (GM, 240 mg/kg/day) or a single dose of cisplatin (CDDP, 5 mg/kg) were euthanized on days 2 (the day after initial dosing) 5, or 12. At each time point, histopathological examination of the kidney and immunohistochemistry for biomarkers, kidney injury molecule-1 (Kim-1), lipocalin (NGAL), clusterin (CLU), cystatin C (CysC) and β2-microglobulin (β2M) were performed. Biomarker levels were measured in urine and blood. In both treatment groups, degenerated/necrotic proximal tubules and regenerated tubules were mainly observed on days 5 and 12, respectively. At the same time as these tubular injuries, urinary Kim-1, CysC and β2M levels were increased. Moreover, urinary levels of CysC and β2M in GM-treated animals and Kim-1 in CDDP-treated animals increased (on day 2) prior to tubular injury on day 5. This was considered to reflect the characteristics of drug toxicity. Although almost all of the biomarkers in blood were not sufficiently sensitive to detect proximal tubular injury, urinary and plasma β2M levels simultaneously increased. Therefore, in addition to urinary Kim-1, CysC and β2M levels, plasma β2M levels were also considered useful for detecting proximal tubular injury.

Use of urinary renal biomarkers to evaluate the nephrotoxic effects of melamine or cyanuric acid in non-pregnant and pregnant rats

Although traditional assessments of renal damage detect loss of kidney function, urinary renal biomarkers are proposed to indicate early changes in renal integrity. The recent adulteration of infant formula and other milk-based foods with melamine revealed a link between melamine ingestion and nephropathy. Thus, the effects of melamine and related analogs (e.g., cyanuric acid) should be assessed in other potentially sensitive groups. We evaluated whether urinary Kim-1, clusterin, and osteopontin could detect the effects of high doses of melamine or cyanuric acid in pregnant and non-pregnant female rats gavaged with 1000 mg/kg bw/day for 10 days. We demonstrate that these biomarkers can differentiate the severity of effects induced by melamine or cyanuric acid. All melamine-treated animals experienced adverse effects; however, pregnant rats were most sensitive as indicated by increased SCr, BUN, and kidney weights, decreased body weight, and presence of renal crystals. These effects coincided with elevated urinary biomarker levels as early as day 2 of exposure. One cyanuric acid-treated rat displayed effects similar to melamine, including increased urinary biomarker levels. This work illustrates that these biomarkers can detect early effects of melamine or cyanuric acid crystal-induced nephropathy and further supports the use of urinary protein immunoassays as a powerful, non-invasive method to assess nephrotoxicity.

Characterization of renal biomarkers for use in clinical trials: effect of preanalytical processing and qualification using samples from subjects with diabetes

BACKGROUND

Identifying the potential for drug-induced kidney injury is essential for the successful research and development of new drugs. Newer and more sensitive preclinical drug-induced kidney injury biomarkers are now qualified for use in rat toxicology studies, but biomarkers for clinical studies are still undergoing qualification. The current studies investigated biomarkers in healthy volunteer (HV) urine samples with and without the addition of stabilizer as well as in urine from patients with normoalbuminuric diabetes mellitus (P-DM).

METHODS

Urine samples from 20 male HV with stabilizer, 69 male HV without stabilizer, and 95 male DM without stabilizer (39 type 1 and 56 type 2) were analyzed for the following bio-markers using multiplex assays: α-1-microglobulin (A1M), β-2-microglobulin, calbindin, clusterin, connective tissue growth factor (CTGF), creatinine, cystatin-C, glutathione S-transferase α (GSTα), kidney injury marker-1 (KIM-1), microalbumin, neutrophil gelatinase-associated lipocalin, osteopontin, Tamm-Horsfall urinary glycoprotein (THP), tissue inhibitor of metalloproteinase 1, trefoil factor 3 (TFF3), and vascular endothelial growth factor.

RESULTS

CTGF and GSTα assays on nonstabilized urine were deemed nonoptimal (>50% of values below assay lower limits of quantification). "Expected values" were determined for HV with stabilizer, HV without stabilizer, and P-DM without stabilizer. There was a statistically significant difference between HV with stabilizer compared to HV without stabilizer for A1M, CTGF, GSTα, and THP. DM urine samples differed from HV (without stabilizer) for A1M CTGF, GSTα, KIM-1, microalbumin, osteopontin, and TFF3. A1M also correctly identified HV and DM with an accuracy of 89.0%.

SUMMARY

These studies: 1) determined that nonstabilized urine can be used for assays under qualification; and 2) documented that A1M, CTGF, GSTα, KIM-1, microalbumin, osteopontin, and TFF3 were significantly increased in urine from P-DM. In addition, the 89.0% accuracy of A1M in distinguishing P-DM from HV may allow this biomarker to be used to monitor efficacy of potential renal protective agents.

Comparison of changes in urinary and blood levels of biomarkers associated with proximal tubular injury in rat models

To investigate useful biomarkers associated with proximal tubular injury, we assessed changes in levels of a focused set of biomarkers in urine and blood. Male rats administered a single dose or four doses of gentamicin (GM, 240 mg/kg/day) or a single dose of cisplatin (CDDP, 5 mg/kg) were euthanized on days 2 (the day after initial dosing) 5, or 12. At each time point, histopathological examination of the kidney and immunohistochemistry for biomarkers, kidney injury molecule-1 (Kim-1), lipocalin (NGAL), clusterin (CLU), cystatin C (CysC) and β2-microglobulin (β2M) were performed. Biomarker levels were measured in urine and blood. In both treatment groups, degenerated/necrotic proximal tubules and regenerated tubules were mainly observed on days 5 and 12, respectively. At the same time as these tubular injuries, urinary Kim-1, CysC and β2M levels were increased. Moreover, urinary levels of CysC and β2M in GM-treated animals and Kim-1 in CDDP-treated animals increased (on day 2) prior to tubular injury on day 5. This was considered to reflect the characteristics of drug toxicity. Although almost all of the biomarkers in blood were not sufficiently sensitive to detect proximal tubular injury, urinary and plasma β2M levels simultaneously increased. Therefore, in addition to urinary Kim-1, CysC and β2M levels, plasma β2M levels were also considered useful for detecting proximal tubular injury.

Evaluation of biomarkers for in vitro prediction of drug-induced nephrotoxicity: comparison of HK-2, immortalized human proximal tubule epithelial, and primary cultures of human proximal tubular cells

There has been intensive effort to identify in vivo biomarkers that can be used to monitor drug-induced kidney damage and identify injury before significant impairment occurs. Kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and human macrophage colony stimulating factor (M-CSF) have been validated as urinary and plasma clinical biomarkers predictive of acute and chronic kidney injury and disease. Similar validation of a high throughput in vitro assay predictive of nephrotoxicity could potentially be implemented early in drug discovery lead optimization to reduce attrition at later stages of drug development. To assess these known in vivo biomarkers for their potential for in vitro screening of drug-induced nephrotoxicity, we selected a panel of nephrotoxic agents and examined their effects on the overexpression of nephrotoxicity biomarkers in immortalized (HK-2) and primary (commercially available and freshly in-house produced) human renal proximal tubule epithelial cells. Traditional cytotoxicity was contrasted with expression levels of KIM-1, NGAL, and M-CSF assessed using ELISA and real-time quantitative reverse transcription PCR. Traditional cytotoxicity assays and biomarker assays using HK-2 cells were both unsuitable for prediction of nephrotoxicity. However, increases in protein levels of KIM-1 and NGAL in primary cells were well correlated with dose levels of known nephrotoxic compounds, with limited correlation seen in M-CSF protein and mRNA levels. These results suggest that profiling compounds against primary cells with monitoring of biomarker protein levels may have potential as in vitro predictive assays of drug-induced nephrotoxicity.

COMPARISON OF LOSARTAN AND LISINOPRIL EFFECTIVENESS FOR GLOMERULAR AND TUBULAR MARKERS OF RENAL DYSFUNCTION IN CHRONIC HEART FAILURE

Aim. To compare the losartan and lisinopril influence on glomerular and tubular markers rates of renal dysfunction in I-III functional class (FC) chronic heart failure (CHF). Material and methods. Totally 92 patients studied with I-III FC CHF. First group (I) consisted of 47 patients taking losartan as addition to standard treatment for 6 months; second group (II) — 45 patients took lisinopril. All patients underwent glomerular filtration rate estimation (MDRD GFR) and enzymes levels in urine: alanine transaminase (ALT), aspartat transaminase (AST), alkaline phosphanase (AP). Results. The results showed that GFR <60 ml/min in I and II groups was found in 18 (38,3%) and 17 (37,8%) patients, resp. Baseline data analysis of urine enzymes that characterize functional condition of renal tubules, showed that in GFR <60 ml/min patients there is significant (p<0,05) increase of ALT, AST, AP in urine: for I group patients by 45,2%, 31,8%, 78,2%, resp., and for II group — 43,6%, 33,5%, 73,9%, resp., comparing to the patients with GFR >60 ml/min. Six month treatment with inclusion of losartan and lisinopril led to decrease of enzymes levels in urine to increase of GFR comparing to baseline. Conclusion. GFR and the level of fermenturia are the early predictors of tubular epitelium in kidneys, and can be treated as early predictors of renal dysfunction in CHF. Six month treatment with losartan and lisinopril increases GFR and significantly decreases fermenturia, hence improving the condition of tubular epithelium and showin nephroprotective effect.