Drug-induced Renal Toxicity Research Articles

Burden and Factors Associated with Renal Dysfunction among People Living with HIV in Dar es Salaam, Tanzania

Renal diseases pose a significant burden of morbidity and mortality, particularly among People Living with HIV (PLHIV). The risks are further compounded by drug-induced renal toxicity, and the growing burden of hypertension, diabetes, and Hepatitis C infections. This study assessed the magnitude and factors associated with renal dysfunction among PLHIV attending clinics in Dar es Salaam, Tanzania. A hospital-based cross-sectional study was conducted between January and March 2022 among 331 PLHIV recruited through a multistage sampling. Renal disease was determined through urine analysis and clinical, demographic, and disease-specific data were collected using a structured questionnaire. The analysis, performed in SPSS version 25, involved descriptive analysis, univariate, and multivariable logistic regression to determine the magnitude and predictors of renal dysfunction among PLHIV. Renal dysfunction was observed in 37 (11.1%) participants. Patients with advanced age were 3.89 times more likely to have renal dysfunction (95% CI: 1.56 – 9.72, p = 0.004) compared to lower age groups. No statistically significant association was found between renal dysfunction and sex, duration from diagnosis of HIV and on ART, ART-based regimen, HIV viral load, hypertension, or diabetes mellitus. More than one in ten PLHIV in Dar es Salaam, Tanzania, presented with signs of renal dysfunctions, which was more significant among patients aged 55 and older. Routine screening for renal diseases among PLHIV, especially for patients with advanced age is essential to prevent and control for progression to renal failure.

Targeted design of a recombinant tracer for SPECT renal imaging.

Rationale: A robust radiopharmaceutical has high uptake in the target and low retention in non-target tissues. However, traditional tracers for renal imaging that chemically chelate 99mTc are excreted through the renal route with transient resident time in the kidney. Following a rational design approach, we constructed a protein-based radiotracer, designated PBT-Fc, to sequentially bind tubular neonatal Fc-receptor and subsequently proximal tubular basement membrane for its targeted sequestration in kidney parenchyma. In this process, the tracer participates in physiologic glomerular filtration and tubular reabsorption while escaping lysosomal catabolism and urinary clearance.Methods: To specifically target renal receptors in navigating the urinary passage in the kidney, we produced a recombinant fusion protein with two separate functional parts: a polybasic PBT segment derived from human Vascular Endothelial Growth Factor and Fc segment of IgG1. The chimeric fusion of PBT-Fc was labeled with radionuclide 99mTc and tested in rodent models of kidney diseases. Planar scintigraphy and single-photon emission computerized tomography (SPECT) were performed to evaluate renal-specificity of the tracer.Results: When injected in mouse and rat, following a brief 10 - 15 min dynamic redistribution phase in circulation, ~ 95% of the [99mTc]-PBT-Fc signal was concentrated in the kidney and lasted for hours without urinary loss or surrounding tissue activities. Long-lasting tracer signals in the kidney cortex in conjunction with SPECT greatly augmented the image quality in detecting pathological lesions in a variety of disease models, including ischemic acute kidney injury, drug-induced renal toxicity, and chronic kidney disease from renin-angiotensin system (RAS) overactivation.Conclusion: Exclusive renal retention of the recombinant radiotracer greatly facilitated static-phase signal acquisition by SPECT and achieved submillimeter spatial resolution of kidney alternations in glomerular and tubular disease models.

A Review on Drug-Induced Nephrotoxicity: Pathophysiological Mechanisms, Drug Classes, Clinical Management, and Recent Advances in Mathematical Modeling and Simulation Approaches.

A variety of marketed drugs belonging to various therapeutic classes are known to cause nephrotoxicity. Nephrotoxicity can manifest itself in several forms depending on the specific site involved as well as the underlying pathophysiological mechanisms. As they often coexist with other pathophysiological conditions, the steps that can be taken to treat them are often limited. Thus, drug-induced nephrotoxicity remains a major clinical challenge. Prior knowledge of risk factors associated with special patient populations and specific classes of drugs, combined with early diagnosis, therapeutic drug monitoring with dose adjustments, as well as timely prospective treatments are essential to prevent and manage them better. Most incident drug-induced renal toxicity is reversible only if diagnosed at an early stage and treated promptly. Hence, diagnosis at an early stage is the need of the hour to counter it. Significant recent advances in the identification of novel early biomarkers of nephrotoxicity are not beyond limitations. In such a scenario, mathematical modeling and simulation (M&S) approaches may help to better understand and predict toxicities in a clinical setting. This review summarizes pathophysiological mechanisms of drug-induced nephrotoxicity, classes of nephrotoxic drugs, management, prevention, and diagnosis in clinics. Finally, it also highlights some of the recent advancements in mathematical M&S approaches that could be used to better understand and predict drug-induced nephrotoxicity.

Drug-induced renal disorder-A Mini Review

Drug-induced kidney disorder/disease (DKID) is an origin of kidney disease followed by acute renal failure. Drug-induced renal toxicity is more common in infants and young children in certain clinical circumstances where underlying renal dysfunction and cardiovascular diseases. Sometimes, administered drugs may cause acute renal injury, intra-renal obstruction, interstitial nephritis, nephrotic syndrome, and acid-base and fluid electrolytes disorders in patients. Certain drugs may cause alterations in intra-glomerular hemodynamics, inflammatory changes in renal tubular cells, leading to acute kidney injury (AKI), interstitial tubule disease, and renal scarring. Common risk factors include; pre-existing renal dysfunction, volume-depleted state, old age, and use of nephrotoxic drugs. Therefore, the prevention from the disease includes the knowledge about the nephrotoxicity, assessing considering the patient-related, kidney-related, and drug-related factors while prescribing medicines, using of alternative drugs, which are non-nephrotoxic, assessing the baseline of renal function before starting the treatment, monitor the renal function during the treatment and avoid the nephrotoxic drug combinations and withdrawing the offending drugs due to toxicity. The ADRs of the prescribed/ administered are identified at the earliest to prevent the development of the last-stage renal disorder. This review discusses the risk factors associated with drug-induced renal disease, estimation of renal function, mechanism of drug-induced nephrotoxicity, and certain drugs that cause nephrotoxicity.

Proximal Tubular Vacuolization and Hypersensitivity to Drug-Induced Nephrotoxicity in Male Mice With Decreased Expression of the NADPH-Cytochrome P450 Reductase.

The effect of variations in the expression of cytochrome P450 reductase (CPR or POR) is determined in mice with decreased POR expression to identify potential vulnerabilities in people with low POR expression. There is an age-dependent appearance of increasing vacuolization in the proximal tubules of the renal cortex in 4- to 9-month-old male (but not female) Cpr-low (CL) mice. These mice have low POR expression in all cells of the body and upregulation of lysosome-associated membrane protein 1 expression in the renal cortex. Vacuolization is also seen in extrahepatic CL and extrarenal CL male mice, but not in mice with tissue-specific Por deletion in liver, intestinal epithelium, or kidney. The occurrence of vacuolization is accompanied by increases in serum blood-urea-nitrogen levels. Male CL mice are hypersensitive to cisplatin- and gentamicin-induced renal toxicity at 3 months of age, before proximal tubular (PT) vacuoles are detectable. At doses that do not cause renal toxicity in wild-type mice, both drugs cause substantial increases in serum blood-urea-nitrogen levels and PT vacuolization in male but not female CL mice. The hypersensitivity to drug-induced renal toxicity is accompanied by increases in circulating drug levels. These novel findings demonstrate deficiency of renal function in mice with globally reduced POR expression and suggest that low POR expression may be a risk factor for drug-induced nephrotoxicity in humans.

The protective effects of saffron stigma alcoholic extract against vincristine sulfate drug-induced renal toxicity in rat

Introduction: Vincristine (VCR) is potential anti-cancer drug that is highly toxic for renal tissue. This study aimed to evaluate the protective effect of alcoholic extract of saffron stigma against vincristine renal toxicity in male rats. Methods: A total number of 50 rats were randomly divided into 10 groups. Different doses of VCR (0.25, 0.5 and 0.75mg/kg) and saffron (0.5 and 1mg/kg) were used to treat vincristine-induced renal toxicity in rats. Serum level of renal biomarkers, creatinine (Cr), uric acid and blood urea nitrogen (BUN) were measured using specific kits at the end of the experimental period. Serum total antioxidant capacity (TAC) and malondialdehyde (MDA) values were measured using Ferric reducing antioxidant of power (FRAP) and Thiobarbituric acid reaction (TBAR) methods, respectively. Results: Administration of VCR to the experimental rats caused severe renal injury with significant increase in the levels of creatinine (Cr), uric acid and blood urea nitrogen (BUN). VCR administration (at concentration of 0.75mg/kg) also significantly increased the mean level of MDA (0.51±0.021 nmol/ml; p<0.001), while TAC value was declined significantly (243.17±16.24 μmol/l; p<0.001). These effects were dose-dependently. Treatment with saffron extract decreased the level of Cr, BUN, and MDA values in VCR-exposed rats with a significant enhancement in serum TAC content. This effect was notable for rats that received 1mg/kg plant extract. Conclusion: Administration of saffron, especially at higher concentration, can reduce VCR-induced renal toxicity, total antioxidant depletion and lipid peroxidation, possibly due to its antioxidative properties.

Fluid shear stress stimulates MATE2-K expression via Nrf2 pathway activation

Accurate prediction of drug-induced renal toxicity is necessary for development of safer drugs for patients. Cellular assay systems that recapitulate physiologically relevant microenvironments have been proposed for correct estimation of drug responses in the human body. However, establishment of such assay systems for accurate prediction of renal toxicity is challenging because of the lack of readily available in vitro assay systems. In this study, we investigated the cellular response to fluid shear stress, which is a characteristic of the environment in the kidney proximal tubules, using microfluidic devices. The global gene expression profiles of human primary proximal tubule cells under the fluidic conditions revealed upregulation of MATE2-K and activation of Nrf2 signaling in response to fluid shear stress. Network and cell biological analysis additionally showed that expression of MATE2-K is regulated by Nrf2 signaling. These results strongly suggest that fluid shear stress is involved in the expression and maintenance of function of tissue-specific drug transporters in the proximal tubule, where the cells are exposed to continuous shear stress by primary urine. Furthermore, the microfluidic culture of human proximal tubules was demonstrated to be a useful system to analyze the regulatory mechanisms of gene expression in physiologically relevant cell conditions.

Nephron segment specific microRNA biomarkers of pre-clinical drug-induced renal toxicity: Opportunities and challenges

Drug-induced nephrotoxicity is a common drug development complication for pharmaceutical companies. Sensitive, specific, translatable and non-invasive biomarkers of renal toxicity are urgently needed to diagnose nephron segment specific injury. The currently available gold standard biomarkers for nephrotoxicity are not kidney-specific, lack sensitivity for early detection, and are not suitable for renal damage localization (glomerular vs tubulointerstitial injury). MicroRNAs (miRNAs) are increasingly gaining momentum as promising biomarkers of various organ toxicities, including drug induced renal injury. This is mostly due to their stability in easily accessible biofluids, ease of developing nucleic acids detection compared to protein detection assays, as well as their interspecies translatability. Increasing concordance of miRNA findings by standardizing methodology most suitable for their detection and quantitation, as well as characterization of their expression pattern in a cell type specific manner, will accelerate progress toward validation of these miRNAs as biomarkers in pre-clinical, and clinical settings. This review aims to highlight the current pre-clinical findings surrounding miRNAs as biomarkers in two important segments of the nephron, the glomerulus and tubules.

A SILAC-Based Approach Elicits the Proteomic Responses to Vancomycin-Associated Nephrotoxicity in Human Proximal Tubule Epithelial HK-2 Cells.

Vancomycin, a widely used antibiotic, often induces nephrotoxicity, however, the molecular targets and underlying mechanisms of this side effect remain unclear. The present study aimed to examine molecular interactome and analyze the signaling pathways related to the vancomycin-induced nephrotoxicity in human proximal tubule epithelial HK-2 cells using the stable isotope labeling by amino acids in cell culture (SILAC) approach. The quantitative proteomic study revealed that there were at least 492 proteins interacting with vancomycin and there were 290 signaling pathways and cellular functions potentially regulated by vancomycin in HK-2 cells. These proteins and pathways played a critical role in the regulation of cell cycle, apoptosis, autophagy, EMT, and ROS generation. These findings suggest that vancomycin-induced proteomic responses in HK-2 cells involvefunctional proteins and pathways that regulate cell cycle, apoptosis, autophagy, and redox homeostasis. This is the first systemic study revealed the networks of signaling pathways and proteomic responses to vancomycin treatment in HK-2 cells, and the data may be used to discriminate the molecular and clinical subtypes and to identify new targets and biomarkers for vancomycin-induced nephrotoxic effect. Further studies are warranted to explore the potential of quantitative proteomic analysis in the identification of new targets and biomarkers for drug-induced renal toxicity.

Statins Against Drug-Induced Nephrotoxicity

Drug-induced nephrotoxicity (DIN) accounts for up to 60% of hospital acquired acute kidney injury with considerable morbidity and mortality. Several efforts have been made to reduce drug-induced nephrotoxicity; however, DIN remains a matter of concern. Statins with their antioxidant, anti-inflammatory and anti-apoptotic effects may have the potential to protect kidney against DIN. The present review evaluated all of the available in vitro and in vivo studies that examined the use of statins as renoprotective agents against nephrotoxic drugs. Materials for this review were obtained by searching Medline, PubMed, Scopus, Cochrane central register of controlled trials, and Cochrane database of systematic reviews. Key words used as search terms included "statin", "3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, "HMG-CoA reductase inhibitors", "nephroprotective", "renoprotective", "drug-induced renal diseases", "drug-induced nephrotoxicity", "drug-induced renal toxicity", "drug-induced nephropathy", "drug-induced renal side effects", and "contrast-induced nephropathy". This search was performed without time limitation. Only English language articles were included in this review. This review concluded that chronic statin user may be less prone to contrast-induced nephropathy (CIN) compared with statin non-users. Short-term high dose statin administration may also reduce the incidence of CIN in statin naïve patients. This renoprotective effect of statins against CIN is seen in low risk patients with normal kidney function or mild kidney dysfunction, but probably not in patients with moderate to severe renal dysfunction. Based on available animal data, statins may protect kidney against gentamicin-, cisplatin- and cyclosporine-induced nephrotoxicity, however, theses animal results have not yet been confirmed by human data. This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.

Renoprotective effect of grape seed extract against oxidative stress induced by gentamicin and hypercholesterolemia in rats

AbstractRationale: Kidneys are dynamic organs and represent one of the major systems maintaining the body homeostasis; they are affected by many chemicals and drugs. Grape seed extract (GSE) has been targeted to prevent drug-induced renal toxicity. Objectives: This study investigates the possible renoprotective effect of GSE against oxidative stress, renal impairment, and hypercholesterolemia (HC) induced by gentamicin (GM) and cholesterol-enriched diet. Seventy adult male Wistar rats (160 ± 10 g) were divided into seven groups: (1) served as control, (2) GSE, (3) GM, (4) GSE + GM, (5) hypercholesterolemic (HC) group, (6) GM + HC group, and (7) GM + HC + GSE. Kidney functions, inflammatory mediators, cytokines, lipid profile, nitric oxide (NO), cyclic guanosine monophosphate (cGMP), and oxidative and antioxidative stress parameters were assessed in all groups. Main findings: GM induced renal dysfunction, which was exacerbated by the presence of HC as confirmed by laboratory determinations. Administration ...

A review of the potential protective effects of pentoxifylline against drug-induced nephrotoxicity

Drug-induced nephrotoxicity is one of the most common side effects of medications and accounts for about 20 % of hospital admissions for acute kidney injury (AKI). Some possible pharmacologic mechanisms of pentoxifylline (PTX) that suggest it as a candidate to ameliorate AKI include interaction at the level of the adenosine receptors, increase in erythrocyte deformability, stimulation of vasodilatory prostaglandins production and prevention of vascular congestion, and suppression of tumor necrosis factor alpha (TNF-α) and apoptosis. This manuscript reviews all clinical and animal studies on the use of PTX as a renoprotective agent against a number of nephrotoxic drugs. Data were collected by searching MEDLINE, PubMed, Scopus, Cochrane central register of controlled trials, and Cochrane database systematic reviews. Key words used as search terms were pentoxifylline, nephroprotective, renoprotective, drug-induced renal diseases, drug-induced nephrotoxicity, drug-induced renal toxicity, and drug-induced nephropathy. This search was performed without time limitation. Most greatest number of studies and human clinical trials on the renoprotective effect of PTX against drug-induced nephrotoxicity involves cyclosporine (Cyc). It seems that despite encouraging results from animal studies, there is insufficient evidence to support the renoprotective effect of PTX against Cyc-induced nephrotoxicity in humans. Although some available animal studies show protective effects of PTX against renal toxicity of some antimicrobial and cytotoxic agents, designing clinical trials to approve these nephroprotective effects requires prior confirmation of no reducing antimicrobial or antitumor action of these medications by PTX.

Renoprotective Effect of Grape Seed Extract against Oxidative Stress Induced by Gentamicin and Hypercholesterolemia in Rats

Rationale: Kidneys are dynamic organs and represent one of the major systems maintaining the body homeostasis; they are affected by many chemicals and drugs. Grape seed extract (GSE) has been targeted to prevent drug-induced renal toxicity. Objectives: This study investigates the possible renoprotective effect of GSE against oxidative stress, renal impairment, and hypercholesterolemia (HC) induced by gentamicin (GM) and cholesterol-enriched diet. Seventy adult male Wistar rats (160 ± 10 g) were divided into seven groups: (1) served as control, (2) GSE, (3) GM, (4) GSE + GM, (5) hypercholesterolemic (HC) group, (6) GM + HC group, and (7) GM + HC + GSE. Kidney functions, inflammatory mediators, cytokines, lipid profile, nitric oxide (NO), cyclic guanosine monophosphate (cGMP), and oxidative and antioxidative stress parameters were assessed in all groups. Main findings: GM induced renal dysfunction, which was exacerbated by the presence of HC as confirmed by laboratory determinations. Administration of GSE attenuated the renal toxicity evidenced in significant reduction in elevated kidney function, inflammatory cytokines as well as lipid profile, NO, cGMP, enzymatic, and nonenzymatic antioxidants. Conclusion: Administration of GSE simultaneously with GM attenuated oxidative stress, diminished renal toxicity, and improved lipid profile induced by GM and HC.

Antiviral agents for treatment of herpes simplex virus infection in neonates

Herpes simplex virus (HSV) is a rare but serious neonatal pathogen. Prior to the availability of antiviral drugs the mortality associated with all but localised neonatal infection was high, with 85% of infants with disseminated HSV infection and 50% of infants with encephalitis dying by one year of age. The morbidity in the survivors of multiorgan infection was also high, with up to 50% experiencing long-term neurological sequelae. To determine the effect of antiviral agents in the treatment of neonatal HSV infections on mortality, progression of disease and neurodevelopmental sequelae at approximately one year. The secondary objective was to assess the effect of antiviral agents on major complications associated with the use of these agents including nephrotoxicity and bone marrow suppression. Trials were identified by searching the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 4, 2008), MEDLINE (1996 - Nov 2008), EMBASE (1982 - Nov 2008) and reference lists of published trials. Randomised and quasi-randomised controlled trials of antiviral therapy in infants less than one month of age with virologically proven HSV infection were included. Data were extracted and the analyses performed independently by two review authors. Studies were analysed for methodological quality using the criteria of the Cochrane Neonatal Review Group. All data were analysed using RevMan 5.1. When possible, meta-analysis was performed to calculate typical relative risk, typical risk difference, along with their 95% confidence intervals (CI). Two eligible studies of a total of 273 infants were included. Both studies were randomized controlled trials. One study treated 63 infants with vidarabine or placebo (Whitley 1980) and the other study treated 210 infants with aciclovir or vidarabine (Whitley 1991).In the study comparing vidarabine with placebo (Whitley 1980), infants with all forms of neonatal HSV disease were included [disseminated disease, central nervous system (CNS) disease alone, and skin, eye and mouth (SEM) disease].There was no significant reduction in the risk of mortality when analyzed as an entire group; however, mortality was significantly reduced when data from infants with CNS disease or disseminated disease were combined. There was no difference in the rate of neurological abnormalities in survivors at one year when analyzed as an entire group or by disease category.There was no difference between aciclovir and vidarabine (Whitley 1991) in preventing mortality from neonatal HSV disease, in preventing disease progression, in reducing the incidence of neurological abnormality at one year, or in the incidence of drug-induced renal or bone marrow toxicity. In infants with SEM disease, there was no significant difference in neurological outcome with aciclovir compared vidarabine treatment. Both drugs were well tolerated in the newborn period. There is insufficient trial evidence to evaluate the effects of antiviral agents with controls or with each other. The rarity of the condition makes effectively powered clinical trials difficult to perform. The efficacy of newer antiviral agents with better bioavailability (e.g. valaciclovir, valganciclovir) for the treatment of neonatal disease needs to be evaluated in randomised trials. The efficacy of oral formulations need to be evaluated as they may be useful for infants with skin, eye or mouth HSV disease or in the treatment of infants with recurrences after the neonatal period.

Toxicité rénale des médicaments

Drug-induced renal dysfunction is frequent in clinical practice. Outcomes may be severe, with increased morbidity and mortality. Kidneys are particularly vulnerable to drug toxicity, especially since they are highly vascularized, thus receiving about 25% of cardiac output. Furthermore, interstitial accumulation of toxic agents in papilla and the medulla often occurs due to the existence of a corticomedullary osmotic gradient. Moreover, the key role played by the renal tubule in the reabsorption processes of a number of endogenous and exogenous substances further increases the exposure of the kidney to high concentrations of potentially toxic agents, both in the tubular lumen and cells. As a result, drugs may be toxic to all of the four structures of the kidney: glomerulus, tubule, interstitium, and blood vessels. This chapter reviews the main mechanisms of drug-induced renal toxicity and then focuses on the nephrotoxicity of anti-infectious drugs: antibacterial drugs, antifungal agents, antimalariae, and antiviral drugs. NSAID and anticancer drugs renal toxicity are detailed elsewhere in this textbook. Methods used to prevent drug-induced nephrotoxicity, when known, are detailed. Risk factors are also listed, such as high-risk populations, identification and elimination of risk factors, and drug dosage adjustment in patients with baseline abnormal renal function.

Age‐Related Differences in Cisplatin‐Induced Renal Toxicity in Rats

A multi‐age rat model was developed and utilized to examine potential age‐dependent differences in drug‐induced renal toxicity caused by cisplatin. Male Sprague‐Dawley rats (10‐, 25‐, 40‐, and 80‐days‐old) were dosed with 0, 1, 3 and 6 mg/kg i.p. cisplatin (cip). The high dose of cip (6 mg/kg) caused: decreased body weight (all ages); decreased kidney weight/body weight (80‐days‐old); moderate to severe renal lesions (tubular necrosis and apoptosis) (all ages except 25‐days‐old); significantly increased serum BUN and creatinine levels (80‐ and 40‐days‐old). This dose also caused increases in the urinary level of the renal biomarkers: kidney injury molecule‐1 (Kim‐1), renal papillary antigen‐1 (RPA‐1) and N‐acetyl‐beta‐D‐glucosaminidase (NAG) in 40‐ (72 hrs) and 80‐ (48 and 72 hrs) day‐old rats; increases only in NAG and RPA‐1 occurred in 25‐day‐old rats (72 hrs). Significant increases in the gene expression levels of 4 nephrotoxicity biomarkers (Kim‐1, Spp1, Lcn2, Clu) were detected in the kidneys from all age groups (except for 25‐days‐old) treated with 6 mg/kg cip. In addition, similar gene expression levels were observed in 40‐ and 80‐day‐old rats given 3 mg/kg cip. Glucosuria and hydroxyprolinuria were detected on day 2 and 3 in 40‐ and 80‐day‐old rats. These findings indicate that certain biomarkers can help identify these age‐related differences in susceptibility.

Diagnosis of drug-induced renal tubular toxicity using global gene expression profiles

Toxicogenomics can measure the expression of thousands of genes to identify changes associated with drug induced toxicities. It is expected that toxicogenomics can be an alternative or complementary approach in preclinical drug safety evaluation to identify or predict drug induced toxicities. One of the major concerns in applying toxicogenomics to diagnose or predict drug induced organ toxicity, is how generalizable the statistical classification model is when derived from small datasets? Here we presented that a diagnosis of kidney proximal tubule toxicity, measured by pathology, can successfully be achieved even with a study design of limited number of training studies or samples. We selected a total of ten kidney toxicants, designed the in life study with multiple dose and multiple time points to cover samples at doses and time points with or without concurrent toxicity. We employed SVM (Support Vector Machine) as the classification algorithm for the toxicogenomic diagnosis of kidney proximal tubule toxicity. Instead of applying cross validation methods, we used an independent testing set by dividing the studies or samples into independent training and testing sets to evaluate the diagnostic performance. We achieved a Sn (sensitivity) = 88% and a Sp (specificity) = 91%. The diagnosis performance underscores the potential application of toxicogenomics in a preclinical lead optimization process of drugs entering into development.

Cisplatin, Gentamicin, and p-Aminophenol Induce Markers of Endoplasmic Reticulum Stress in the Rat Kidneys

In vitro evidence of the involvement of the endoplasmic reticulum (ER) during drug-induced renal toxicity is accumulating. ER stress and ER-mediated cell death markers have been reported after exposure of renal cells to model toxicants and nephrotoxic drugs in various in vitro models, but in vivo experiments with clinically relevant nephrotoxic compounds are lacking. In order to determine the relevance of the in vitro findings, markers of ER stress (XBP1 messenger RNA processing and protein expression; GRP78 and GRP94 upregulation) and ER-mediated cell death (caspase-12 and calpain activation) were examined in kidney tissue of rats exposed to nephrotoxic doses of cisplatin (CIS), gentamicin (GEN), and p-aminophenol (PAP), a nephrotoxic metabolite of acetaminophen. XBP1 signaling was observed with all three drugs and was associated with increased expression of GRP94 and GRP78 in GEN- and PAP-treated animals, but surprisingly not after CIS exposure. m-Calpain expression was increased after 7 days of CIS treatment, whereas it was decreased in PAP-treated rats. Caspase-12 cleavage products were increased after CIS, GEN, and PAP administration. The results of this study demonstrate that three clinically relevant nephrotoxic drugs are all associated with changes in markers of ER stress and ER-mediated cell death in vivo. Further investigation is warranted to determine the role of the ER, the calpain system, and caspase-12 in drug-induced renal cell death.

Effect of endoplasmic reticulum stress preconditioning on cytotoxicity of clinically relevant nephrotoxins in renal cell lines

The cytoprotection of LLC-PK1 cells afforded by endoplasmic reticulum (ER) stress preconditioning suggests that the ER plays an important role during drug-induced renal toxicity. However, in vitro studies have been largely limited to LLC-PK1 cells and model toxins. Therefore, we tested the hypothesis that cytoprotection following ER stress preconditioning is a common property of renal cell lines (LLC-PK1 (pig), NRK-52E (rat), HEK293 (human), MDCK (dog)) and extends to clinically relevant nephrotoxins. ER stress inducers (tunicamycin, thapsigargin and oxidized dithiothreitol (DTTox)) resulted in a dose-dependent increase in GRP78 and GRP94 stress protein expression, but the magnitude of induction was cell line- and inducer-dependent. Toxicity of the model toxins iodoacetamide and tert-butylhydroperoxide was modified by preconditioning. DTTox was effective in decreasing the toxicity in all cell lines, but protection was variable with tunicamycin and thapsigargin. Toxicity of clinically relevant drugs (cisplatin, gentamicin, glyoxylate, cyclosporine A, p-aminophenol) was significantly decreased in cells preconditioned by tunicamycin or DTTox. These results demonstrate that ER stress preconditioning offers cytoprotection against clinically relevant nephrotoxins in renal cell lines from multiple species, although there were qualitative and quantitative differences between the cell lines. These results support the hypothesis that ER is involved in drug-induced renal toxicity.

A Gene Expression Signature that Predicts the Future Onset of Drug-Induced Renal Tubular Toxicity

One application of genomics in drug safety assessment is the identification of biomarkers to predict compound toxicity before it is detected using traditional approaches, such as histopathology. However, many genomic approaches have failed to demonstrate superiority to traditional methods, have not been appropriately validated on external samples, or have been derived using small data sets, thus raising concerns of their general applicability. Using kidney gene expression profiles from male SD rats treated with 64 nephrotoxic or non-nephrotoxic compound treatments, a gene signature consisting of only 35 genes was derived to predict the future development of renal tubular degeneration weeks before it appears histologically following short-term test compound administration. By comparison, histopathology or clinical chemistry fails to predict the future development of tubular degeneration, thus demonstrating the enhanced sensitivity of gene expression relative to traditional approaches. In addition, the performance of the signature was validated on 21 independent compound treatments structurally distinct from the training set. The signature correctly predicted the ability of test compounds to induce tubular degeneration 76% of the time, far better than traditional approaches. This study demonstrates that genomic data can be more sensitive than traditional methods for the early prediction of compound-induced pathology in the kidney.