Metabolic interactions between drugs and renal tubulointerstitial cells: role in nephrotoxicity

Modulatory Effect of Dietary Inclusion of Aegle marmelos Fruits against Cisplatin - Induced Hepatotoxicity In Wistar Rats

INTRODUCTION AND AIM

Aegle marmelos is an important traditional herbal medicine used in India. The dietary inclusion of the plant has never exposed earlier for its hepatoprotective activity. This study aimed to investigate the modulator efficacy of dietary inclusion of Aegle marmelos against Cisplatin - induced hepatotoxicity in Wistar albino rats.

MATERIAL AND METHODS

Animals were divided into five different groups; Group I was given basal diets only, Group II was fed basal diets with Aegle marmelos in 4% concentration, while Group III was fed basal diets co-administered with Cisplatin. Group IV and V were administered diets containing 2 and 4% Aegle marmelos respectively, for 27 days prior to Cisplatin administration. Cisplatin was administered to the rats for 3 days leads to a reduction in the activities of the antioxidant enzymes like lipid peroxidation (LPO) and endogenous antioxidant systems such as reduced superoxide dismutase (SOD), glutathione (GSH) and catalase in liver homogenate caused to produce the impairment of hepatic functions.

RESULTS

The administration of fruit part of Aegle marmelos to Wistar rats showed a significant fall in the elevated Lipid peroxidation, superoxide dismutase, glutathione and catalase concentration, moreover, it diminished the increased serum level of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), acid phosphatase (ACP) and bilirubin.

CONCLUSIONS

We can conclude that the hepatoprotective activity of Aegle marmelos was due to its antioxidant effect as evidenced by increasing activity of antioxidant enzymes with enhanced hepatic function and significantly changed the physiological parameters.

Characterization of Acetaminophen Toxicity in Human Kidney HK-2 Cells

Acetaminophen (APAP) overdose causes liver injury, but in some cases it is associated also with renal impairment. While several studies exist in relation to acetaminophen nephrotoxicity, no reports have been published describing intracellular changes related to APAP nephrotoxicity in vitro. Because proximal tubular cells are considered to constitute a secondary site of drug-induced injury after hepatocytes, our study's aim was to estimate the toxicity in the human HK-2 cell line. We used a range of APAP concentrations (1-10 mM) to examine toxicity in the cells (1-48 h). We evaluated cell viability using the WST-1 and LDH tests. Cells impairment was also determined by monitoring ROS production, glutathione levels. We proved that HK-2 cells are able to metabolize acetaminophen. We observed moderate impairment of cells already after 1 h of treatment based on a finding of increased ROS production and decreased cell viability. After 24 h, the results showed significant cellular impairment at all tested concentrations except for 1 mM APAP, but no glutathione depletion was found. We conclude that HK-2 cells are susceptible to acetaminophen toxicity but, unlike hepatocytes, it might be not linked to glutathione depletion.

Effect of platelet activating factor antagonist treatment on gentamicin nephrotoxicity

To assess whether PAF could be involved in the gentamicin-induced nephrotoxicity, we have studied the effect of PAF antagonist BN-52021 on renal function in rats after gentamicin (GENTA) treatment. Experiments were completed in 21 Wistar rats divided into three groups: group GENTA was injected with gentamicin 100 mg kg⁻¹ body wt/day s.c. for 6 days. Group GENTA + BN received gentamicin and BN-52021 i.p. 5 mg kg⁻¹ body wt/day. A third group served as control. Rats were placed in meta-bolic cages and plasma creatinine and creatinine clearance were measured daily. GENTA group showed a progressive increase in plasma creatinine, a drop in creatinine clearance and an increase in urinary excretion of N-acetyl-β-D-glucosaminidase and alkaline phosphatase. GENTA + BN group showed a lesser change in plasma creatinine and a creatinine clearance, but no difference with GENTA group in urinary excretion of NAG and AP were observed. Histological examination revealed a massive cortical tubular necrosis in rats treated with gentamicin, whereas in BN-52021 injected animals tubular damage was markedly attenuated. The present results suggest a role for PAF in the gentamicininduced nephro-toxicity.

Resveratrol inhibits gentamicin-induced mesangial cell contraction

Gentamicin is an aminoglycoside antibiotic that is very effective in treating different gram negative infections, however, one of its main side effects is nephrotoxicity. Gentamicin-induced decreases in glomerular filtration rate could be mediated by mesangial cell contraction. Resveratrol, a natural hydroxystilbene, has been identified to be a potent antioxidant with many biological activities including protection against kidney diseases. As we have previously demonstrated that gentamicin induced a reduction of planar surface area of cultured rat mesangial cells, and that resveratrol has a protective effect on gentamicin-induced nephrotoxicity in vivo, the aim of this study was to investigate the effect of resveratrol on gentamicin-induced mesangial cell contraction. This study demonstrates that the contractile effect of gentamicin on mesangial cells can be prevented by incubation with resveratrol at an optimal dose of 10 microM, as it blunted the gentamicin-induced reduction in planar cell surface area and the number of contracted cells. Besides, the preincubation with 10(-5)M diphenylene iodinium (DPI), an inhibitor of the NADP(H) oxidase, also blunted gentamicin-induced cell contraction. This preventive effect was higher when cells were incubated with both substances together. These results strongly suggest that the protective effect resveratrol against gentamicin-induced reduction in renal function in vivo could be mediated by inhibiting gentamicin-induced mesangial cells contraction.

Acute renal failure: is nitric oxide the bad guy?

Nephrotoxicity is a major side effect in clinical practice, frequently leading to acute renal failure (ARF). Many physiological mechanisms have been implicated in drug-induced renal injury. Currently, nitric oxide (NO) is considered to be an important regulator of renal vascular tone and a modulator of glomerular function under both basal and physiopathological conditions. Historically, NO has been implicated in ARF and, after its discovery, several publications have suggested that changes in NO production could play an important role in the hemodynamic alterations observed in ARF. In this review, we evaluate the participation of NO in ARF and summarize many of the findings in this research area in an attempt to elucidate the role of NO in ARF.

Protective effect of trans-resveratrol on gentamicin-induced nephrotoxicity

Reactive oxygen species (ROS) have been involved in glomerular filtration rate (GFR) reduction observed after gentamicin treatment. trans-Resveratrol (TR), a natural hydroxystilbene, has been identified to be a potent inhibitor of ROS production. The aim of this work has been to study whether TR has a protective effect on gentamicin-induced nephrotoxicity in vivo and the effect of TR on lipid peroxidation and the oxidative stress induced by gentamicin. Animals that received a daily intraperitoneal injection of gentamicin (100 mg/kg body weight) showed lower GFR and renal blood flow (RBF) and higher urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG) than control rats. Rats receiving TR together with gentamicin showed higher GFR and RBF and lower NAG urinary excretion than rats receiving gentamicin alone. Moreover, renal lipid peroxidation increased in rats receiving gentamicin alone, and this increase was prevented by the administration of TR. The concentration in plasma of antioxidants was higher in the group that received TR with gentamicin than in the gentamicin and control groups. The activities of lactate dehydrogenase and alkaline phosphatase were higher in rats treated with gentamicin than in control rats and were reduced by the treatment with TR. This study demonstrates an improvement in renal function in response to the administration of TR in gentamicin-induced nephrotoxicity. At least a part of this effect of TR could be based on its antioxidant activity.

Renal transport of antibiotics and nephrotoxicity: a review

The renal excretion of a drug can essentially be divided schematically into three functional processes: glomerular filtration, tubular reabsorption and tubular secretion. When assessing nephrotoxicity, the tubular secretion system, which allows transport of the drug from the blood to the urine via the tubular cells, is particularly important. Historically, two distinct tubular secretion mechanisms have been described for drugs: one via organic cations and the other via organic anions. More recently, a third tubular secretion mechanism has been identified, mediated by P-glycoprotein. In the present review, a number of examples will be given relating to antibiotic-induced kidney damage determined via the tubular reabsorption mechanism (aminoglycosides, amphotericin B) and via the tubular secretion mechanism (cephalosporins, vancomycin), respectively. Drug transport within the tubular cells is the first fundamental stage in the onset of the nephrotoxic process. Knowledge of these concepts is important for the prevention of iatrogenic kidney damage, particularly in patients with underlying disease receiving concomitant treatment with several potentially nephrotoxic molecules.

Regenerative response in acute renal failure due to vitamin E deficiency and glutathione depletion in rats

In this study, we investigated some factors contributing to renal regeneration after acute renal failure (ARF) induced by vitamin E (VE) deficiency and glutathione (GSH) depletion. Acute renal failure was induced by feeding rats a vitamin E-deficient diet for 6 weeks and then injecting buthionine sulfoximine (BSO), a glutathione-depleting agent. The level of hepatocyte growth factor (HGF), a renotropic factor for regeneration in the kidney, showed a transient increase at 5 hr after the BSO treatment. Subsequently, renal ornithine decarboxylase (ODC) activity, a marker of G1 phase, and labeling index (LI) of proliferating cell nuclear antigen (PCNA), a marker of DNA synthesis (S phase), reached peaks at 10 and 53 hr after the injection, respectively. Thus, it appears that the increase in ornithine decarboxylase activity and subsequent elevation in proliferating cell nuclear antigen labeling index following the increase in the hepatocyte growth factor level in the kidneys are closely related to the renal regenerative response after acute renal failure.

L-Arginine inhibits vasopressin-stimulated mesangial cell Ca2+

L-Arginine (L-Arg) affects various parameters that modulate the progression of renal disease. These same factors [e.g., glomerular filtration rate, changes in mesangial cell (MC) tension, and production of NO] are all controlled at least in part by changes in MC intracellular Ca2+ concentration ([Ca2+]i). We therefore evaluated the effect of L-Arg on MC [Ca2+]i. We found that L-Arg inhibits the vasopressin-stimulated rise in MC [Ca2+]i both in rat and murine cell cultures. This effect does not appear to be due to metabolism of L-Arg to either NO or L-ornithine (L-Orn). Blocking the metabolism of L-Arg with Nomega-monomethyl-L-arginine, an NO synthase inhibitor, or with 20 mM L-valine (L-Val), an inhibitor of Orn formation, does not reverse the inhibition. However, other cationic amino acids, as well guanidine, the functional group of L-Arg, all inhibit the vasopressin-stimulated rise in [Ca2+]i, consistent with a structural basis for this effect. We conclude that 1) L-Arg inhibits vasopressin-stimulated murine and rat MC [Ca2+]i rise, 2) this inhibition is not mediated by metabolism of L-Arg to either NO or L-Orn, and 3) the effect of L-Arg is due to its cationic functional group, guanidine.

The repetitive activation of extracellular signal-regulated kinase is required for renal regeneration in rat

In this study, we investigated the activation of p42 extracellular signal-regulated kinase (ERK2) during renal regeneration after HgCl2-induced acute renal failure (ARF) in rat. ERK2 activation was observed at 5 and 29 hr after HgCl2 injection, respectively. The tyrosine phosphorylation of hepatocyte growth factor receptor (c-MET) occurred between 2.5 and 5 hr after the treatment. On the other hand, the phosphorylation of epidermal growth factor receptor (EGFR) was transiently observed at 29 hr after the injection. The peak of ornithine decarboxylase activity as a marker of G1 phase was at 10 hr, and subsequently the labeling index of proliferating cell nuclear antigen as a marker of S phase increased at 53 hr. These results indicate that the repetitive activation of ERK2 related to the phosphorylation of c-MET and EGFR is required for the renal regeneration in HgCl2-induced ARF of rat.

Xenobiotic metabolizing enzymes of the kidney

The kidney possesses most of the common xenobiotic metabolizing enzymes, and is thus able to make an important contribution to the body's metabolism of drugs and foreign compounds. An overview of the renal localization, catalytic activity, developmental regulation, induction, and sex and species differences for the key enzymes involved in phase I and phase II of xenobiotic metabolism is presented. In general, the catalytic activities of the various renal enzymes are lower than those of the liver, although there are exceptions, such as the enzymes involved in the processing of glutathione conjugates to their mercapturic acids. Xenobiotic metabolizing enzymes are not evenly distributed along the nephron; cytochromes P-450 and those enzymes involved in the conjugation of glutathione, glucuronic acid, or sulfate are primarily localized in the proximal tubules. However, some isozymes of cytochrome(s) P-450 and glutathione S-transferases are selectively localized in cells of the thick ascending limb and distal tubules, whereas prostaglandin H synthase is concentrated in the collecting ducts in the medulla. Thus, the proximal tubule, the principal site of xenobiotic biotransformation, is particularly susceptible to chemical insult, and the localization of prostaglandin synthase in the inner medulla and papilla may be a contributary factor to the toxicity produced by chemicals in this part of the nephron. Many of the enzymes discussed, in addition to metabolizing foreign compounds, have important endogenous functions in the kidney, such as the regulation of salt and water balance and the synthesis of vitamin D.

Gentamicin activates rat mesangial cells. A role for platelet activating factor

Gentamicin-induced decreases in glomerular filtration rate have been associated with a marked decline in the glomerular capillary ultrafiltration coefficient which could be mediated by mesangial cell contraction or release of vasoactive hormones. We studied the effect of gentamicin on mesangial cells proliferation, contraction and Ca2+ mobilization. Moreover, we attempted to assess a possible role of platelet activating factor (PAF) as a mediator of the observed effects of gentamicin on mesangial cells. Gentamicin induced a reduction of planar surface area of cultured rat mesangial cells that was blunted by the PAF-antagonist, BN-52021. Gentamicin induced an increase in [Ca2+]i that was inhibited by BN-52021. Gentamicin also stimulated [3H]thymidine incorporation into DNA, an effect that was also reduced by BN-52021, and by other two structurally different PAF receptor antagonists: alprazolam and BB-823. Gentamicin induced c-fos mRNA expression in quiescent mesangial cells. Gentamicin stimulated the synthesis and release of PAF in cultured rat mesangial cells. The present studies demonstrate that gentamicin activates mesangial cell function. These actions seem to be mediated, at least in part, by PAF synthesis and release.

Renal handling of drugs and amino acids after impairment of kidney or liver function--influences of maturity and protective treatment

Renal tubular cells are involved both in secretion and in reabsorption processes within the kidney. Normally, most xenobiotics are secreted into the urine at the basolateral membrane of the tubular cell, whereas amino acids are reabsorbed quantitatively at the luminal side. Under different pathological or experimental circumstances, these transport steps may be changed, e.g., they may be reduced by renal impairment (reduction of kidney mass, renal ischemia, administration of nephrotoxins) or they may be enhanced after stimulation of transport carriers. Furthermore, a distinct interrelationship exists between excretory functions of the kidney and the liver. That means liver injury can influence renal transport systems also (hepato-renal syndrome). In this review, the following aspects were included: based upon general information concerning different transport pathways for xenobiotics and amino acids within kidney cells and upon a brief characterization of methods for testing impairment of kidney function, the maturation of renal transport and its stimulation are described. Similarities and differences between the postnatal development of kidney function and the increase of renal transport capacity after suitable stimulatory treatment by, for example, various hormones or xenobiotics are reviewed. Especially, renal transport in acute renal failure is described for individuals of different ages. Depending upon the maturity of kidney function, age differences in susceptibility to kidney injury occur: if energy-requiring processes are involved in the transport of the respective substance, then adults, in general, are more susceptible to renal failure than young individuals, because in immature organisms, anaerobic energy production predominates within the kidney. On the other hand, adult animals can better compensate for the loss of renal tissue (partial nephrectomy). With respect to stimulation of renal transport capacity after repeated pretreatment with suitable substances, age differences also exist: most stimulatory schedules are more effective in young, developing individuals than in mature animals. Therefore, the consequences of the stimulation of renal transport can be different in animals of different ages and are discussed in detail. Furthermore, the extent of stimulation is different for the transporters located at the basolateral and at the luminal membranes: obviously the tubular secretion at the contraluminal membrane can be stimulated more effectively than reabsorption processes at the luminal side.

Changes associated with long-term oral administration of the penem antibiotic FCE 22891 to rats and monkeys with particular emphasis on the urinary tract and the urine

FCE 22891, a synthetic beta-lactam antibiotic of the penem class, was administered by gavage to Sprague-Dawley rats and cynomolgus monkeys for 26 wk (with and without a 6-wk recovery). Rats received the test material at doses of 0, 200, 500, and 1,250 mg/kg/day, and monkeys were given doses of 0, 100, 200, 400, and 600 mg/kg/day. At the end of the 26-wk treatment period, approximately two-thirds of the animals (both species) were sacrificed, and the remaining animals were held without treatment for a further 6 wk. A treatment-related mortality occurred in female monkeys receiving 600 mg/kg. There was a reduction in body weight gain in the high-dose groups of both species. Male rats were more affected than the females and, conversely, female monkeys were affected more than the males. At higher dose levels, both species exhibited an early, but transient, azotemia and oliguria with an increase in specific gravity and reduced pH. In rats, microscopic examination revealed treatment-related renal cortical tubular degenerative and regenerative changes with associated interstitial inflammation and fibrosis and diffuse urothelial hyperplasia in the urinary bladder. In general, female rats were less severely affected, and in both sexes there was a trend to recovery of most of these effects. In monkeys given 600 mg/kg of the test material, renal cortical tubular degeneration was seen only in those females that died in the first 5 wk of dosing. In other animals at this dose level, the renal lesions were determined to be reversible.

Gentamicin nephrotoxicity in rats is not modified by verapamil

To assess whether calcium could be involved in the gentamicin-induced nephrotoxicity, we have studied the effect of the calcium channel blocker verapamil on renal function in rats intoxicated by gentamicin. Male Wistar rats were divided in three groups. In group I (n = 7) they were injected with gentamicin 100 mg/kg body wt/day s.c. for 5 days. In group II (n = 6), they received gentamicin and verapamil s.c. 2 mg/rat/day. In group III rats served as control. Plasma creatinine and creatinine clearance were daily measured. Rats treated with gentamicin showed a progressive increase in plasma creatinine and a drop in creatinine clearance. No differences between rats treated with gentamicin and those with gentamicin plus verapamil were observed. The urinary flow decreased after treatment with gentamicin, this decrease being more marked in rats treated with verapamil. No differences in daily urinary sodium and potassium excretion were found between intoxicated rats treated or not with verapamil. The present results show that, in rats, verapamil has no protective effect against the nephrotoxicity of gentamicin.

Altered growth factor expression during toxic proximal tubular necrosis and regeneration

Growth factor expression was investigated during the regenerative response after toxic proximal tubular necrosis. Therefore, gentamicin was administered to rats to achieve an experimental model, characterized by the appearance of segment-specific proximal tubular necrosis, that is followed by a regenerative response leading to functional and morphological recovery in a limited time. Four days after the administration of the highest dose, serum creatinine rose to a mean value of 5.8 mg/dl and returned to normal values ten days after the treatment. The S1-S2 segment of the proximal tubules in the cortex became clearly affected by severe toxic necrosis one day after the treatment, while maximal necrosis was observed at days 2 to 4. Only minor injuries were noticed in the other renal compartments. The proliferative response started in the interstitial cells first. The major proliferative wave was localized in the convoluted part of the proximal tubules at days 6 to 8, although proliferation was also prominent among non-proximal tubular cells. A profound interstitial infiltration of leukocytes, including macrophages and T lymphocytes, was observed. Ten days after the treatment the functional and morphological recovery were completed. Slot blot hybridization revealed a decreased EGF and IGF-I mRNA expression from the start of the observation period. While IGF-I mRNA had regained its normal expression at day 10, EGF mRNA was still below control levels. The PDGF-B transcript became more abundant towards the end of our observation. No major changes in the expression of TGF-alpha, TGF-beta 1 and c-fos were detected. Renal EGF-immunoreactivity disappeared from the luminal plasma membrane of the distal tubular cells analogous to the results obtained at the messenger level. However, EGF-staining was lost in the cortex first, hence a topographical association between the loss of EGF-immunoreactivity in the distal tubules and the observed necrotic lesions in the proximal tubules was found. Immunoreactive EGF was never observed in proximal tubular cells from normal, injured or regenerating rat kidneys. We conclude that in this experimental rat model, EGF and IGF-I mRNA expression is decreased during the regenerative response upon severe toxic tubular necrosis. No evidence for a participation of EGF or IGF-I of renal origin in the recovery of the kidney is found.

Effect of gentamicin treatment on glutamine and lactate metabolism by the renal cortex of the rat

The present study was performed to measure the uptake of main renal cortical fuel substrates (glutamine and lactate) and the release of the main renal cortical products (ammonia and glucose) by cortical slices from gentamicin-treated rats. Experiments were done in 2 groups of female Wistar rats (250 g): In gentamicin group (n = 13), rats were injected s.c. with gentamicin-sulphate 100 mg/Kg body wt/day for 5 days. Control rats (n = 13) received isotonic saline. After anesthesia and blood sampling, renal cortical slices were obtained and incubated with L-glutamine and/or lactate at 1 or 5 mM concentration, containing L-glutamate and/or pyruvate at 0.1 or 0.5 mM. Creatinine clearance was reduced to a 50% in gentamicin-treated rats. In addition these animals showed a sharp increase in urinary excretion of N-acetyl-beta-D-glucosaminidase and alkaline phosphatase. Light microscopy examination revealed extensive cell necrosis and tubular obstruction of the proximal tubules in kidneys of rats injected with gentamicin. The renal cortical gentamicin concentration of rats injected with gentamicin was 310 +/- 43 mu/g, whereas it was undetectable in control rats. Cortical slices from gentamicin-treated rats, compared to control ones, showed a reduced production of ammonia and glucose, without differences in glutamine or lactate extraction. These alterations can be explained by both the increased rate of anabolic reactions to recover cell damage associated to renal failure, as well as by a direct effect of gentamicin on the rate of carboxylation reactions.

Drug-induced renal disease

OBJECTIVE

To review drug-induced renal disease with emphasis on current issues and practical problems with commonly used agents.

DATA SOURCES

English language literature search using MEDLINE, Index Medicus, textbook articles and relevant reviews.

STUDY SELECTION

Drugs in common use were reviewed in detail. Uncommonly used drugs or those with only a few reports of nephrotoxicity were excluded from this review.

DATA SYNTHESIS

The clinical patterns of nephrotoxicity include an episode of acute deterioration of renal function, chronic renal failure and proteinuria which may be severe enough to cause the nephrotic syndrome. Diagnosis is made by clinical suspicion, distinctive clinical patterns and usually improvement in renal function on drug withdrawal.

CONCLUSION

A high index of suspicion is necessary to detect drug-induced renal disease particularly with increasing availability of over-the-counter drugs. Drugs should always be suspected of causing renal disease where no alternative cause is obvious. When any doubt exists the agent in question should be withdrawn.