p38 MAP kinase inhibition ameliorates cisplatin nephrotoxicity in mice

Cisplatin is an important chemotherapeutic agent but can cause acute renal injury. Part of this acute renal injury is mediated through tumor necrosis factor-alpha (TNF-alpha). The pathway through which cisplatin mediates the production of TNF-alpha and injury is not known. Cisplatin activates p38 MAPK and induces apoptosis in cancer cells. p38 MAPK activation leads to increased production of TNF-alpha in ischemic injury and in macrophages. However, little is known concerning the role of p38 MAPK in cisplatin-induced renal injury. Therefore, we examined the effect of cisplatin on p38 MAPK activity and the role of p38 MAPK in mediating cisplatin-induced TNF-alpha production and renal injury. In vitro, cisplatin caused a dose-dependent activation of p38 MAPK in proximal tubule cells. Inhibition of p38 MAPK activation led to inhibition of TNF-alpha production. In vivo, mice treated with a single dose of cisplatin (20 mg/kg body wt) developed severe renal dysfunction at 72 h [blood urea nitrogen (BUN): 154 +/- 34 mg/dl, creatinine: 1.4 +/- 0.4 mg/dl], which was accompanied by an increase in kidney p38 MAPK activity and an increase in infiltrating leukocytes. However, animals treated with the p38 MAPK inhibitor SKF-86002 along with cisplatin showed less renal dysfunction (BUN: 55 +/- 14 mg/dl, creatinine: 0.3 +/- 0.02 mg/dl, P < 0.05), less severe histological damage, and fewer leukocytes compared with cisplatin+vehicle-treated animals. Serum levels of TNF-alpha, sTNFRI, and sTNFRII also increased significantly in cisplatin-treated mice compared with SKF-86002-treated mice (P < 0.05). Kidney mRNA levels of TNF-alpha were significantly increased in cisplatin-treated mice compared with either SKF-86002- or saline-treated animals. The hydroxyl radical scavenger DMTU (100 mg.kg body wt(-1).day(-1)) prevented the activation of p38 MAPK by cisplatin both in vitro and in vivo. DMTU also completely prevented cisplatin-induced renal injury (BUN: 140 +/- 27 vs. 22 +/- 2 mg/dl, P < 0.005) and the increase in serum TNF-alpha (33 +/- 7 vs. 4 +/- 2 pg/ml, P < 0.005) and kidney TNF-alpha mRNA in vivo. We conclude that hydroxyl radicals, either directly or indirectly, activate p38 MAPK and that p38 MAPK plays an important role in mediating cisplatin-induced acute renal injury and inflammation, perhaps through production of TNF-alpha.

Mobilization of bone marrow cells by G-CSF rescues mice from cisplatin-induced renal failure, and M-CSF enhances the effects of G-CSF

Cisplatin, which is a broadly used anticancer drug, is widely known to induce acute renal failure as a result of renal tubular injury. This article examines whether G-CSF and/or M-CSF rescues mice from renal failure induced by cisplatin. BALB/c mice received intraperitoneal injections with or without G-CSF and/or M-CSF for 5 d (from day -5 to day -1). The day after the last injection of G-CSF and/or M-CSF (day 0), the mice received an intraperitoneal injection of cisplatin. When pretreated with G-CSF or G-CSF + M-CSF, the mice showed longer survival and lower serum creatinine and blood urea nitrogen levels than mice that had been received injections of M-CSF or saline. Histologically, pretreatment with G-CSF or G-CSF + M-CSF attenuated the damage to renal tubules induced by cisplatin. BALB/c mice that had received a transplant of bone marrow cells of enhanced green fluorescent protein (EGFP)-transgenic mice ([EGFP-->BALB/c] mice) were treated with or without G-CSF and/or M-CSF, followed by injection of cisplatin as well as above. [EGFP-->BALB/c] mice that were treated with G-CSF or G-CSF + M-CSF showed a significantly higher number of EGFP(+) tubular epithelial cells in the kidney than mice that were treated with only M-CSF or saline. These results suggest that bone marrow cells mobilized by G-CSF accelerate the improvement in renal functions and prevent the renal tubular injury induced by cisplatin and that M-CSF enhances the effects of G-CSF.

Nephrotoxicity of platinum complexes is related to basolateral organic cation transport

BACKGROUND

Cisplatin and its analogs oxaliplatin and carboplatin are widely used antitumor drugs. Nephrotoxicity is a common and relevant adverse effect that occurs especially in cisplatin therapy. Cellular and molecular mechanisms of cisplatin-induced nephrotoxicity are not completely understood. The nephrotoxicity of platinum complexes was evaluated by a new in vitro system that utilizes the high Trans Epithelial Electrical Resistance (TEER) of the C7 clone of the MDCK (Madin-Darby canine kidney) cells. By means of this assay system we addressed the question whether the side of application of renal epithelia influences platinum complex toxicity.

METHODS

C7 cells were grown in membrane filter cups, and the apical or basolateral membranes were exposed to 100-micromol/L cis-, oxali-, or carboplatin. TEER and caspase-3 activity were determined. Cimetidine was used as an inhibitor of organic cation transporters (OCTs). C7 cell lysates were analyzed for OCT-1 and -2 by Western blot analysis.

RESULTS

TEER dropped by 89.5 +/- 9.3% (mean +/- SEM; N= 6) within 24 hours after addition of cisplatin to the basolateral side of C7 cells, while caspase activity increased up to 840.6 +/- 17.4% (mean +/- SEM; N= 6) compared to control cells. Exposure of the apical membrane to cisplatin reduced TEER by only 13.4 +/- 8.7% (mean +/- SEM; N= 6), and increased caspase-3 activity up to 213.9 +/- 7.6% (mean +/- SEM; N= 6). Oxaliplatin and carboplatin reduced TEER to a lesser extent than cisplatin. Oxaliplatin lowered TEER stronger than carboplatin. In general, basolateral application led to higher caspase activities and lower TEERs. The OCT-inhibitor cimetidine inhibited the TEER decrease induced by platinum complexes. Immunoblotting confirmed the presence of OCT-2 in C7 cells.

CONCLUSION

Toxic effects of platinum complexes on renal epithelia depend on the platinum complex used and the site of application. We conclude that cell polarity and basolateral transport mechanisms are essential in nephrotoxicity of platinum drugs.

Polymorphism of host response genes: Implications in the pathogenesis and treatment of acute renal failure

Acute inflammatory disorders are the result of an interaction between genetic and environmental factors, and are often characterized by an imbalance between pro- and anti-inflammatory host immune responses. Over the past decade, polymorphisms of host response genes have been explored as genetic risk and prognostic markers in the course and severity of acute inflammatory disorders. Increasing evidence supports an important role for inflammatory mechanisms in the pathogenesis of acute renal failure (ARF) following both ischemic and nephrotoxic injury. The use of genetic epidemiology may become a useful tool to identify patients with an altered susceptibility to developing hospital-acquired ARF, and stratify those who may benefit from preventive therapies that modulate host immune responses in a favorable way. This review summarizes the existing experimental and clinical studies supporting the role of inflammation in ARF and critically appraises studies that have examined polymorphism of immune response genes as potential determinants of susceptibility to and severity of acute inflammatory disorders. Conclusions are drawn on the application of genetic epidemiology to the field of ARF and the rationale for further research on the role of genetic markers in ARF.

Lack of the growth factor midkine enhances survival against cisplatin-induced renal damage

Although cisplatin acts directly on proximal tubule epithelial cells and causes cell death, little is known regarding the biological significance of its secondary effects, such as inflammation. The growth factor midkine is highly expressed in the proximal tubule and exerts ambivalent activities as to cisplatin nephrotoxicity, ie, anti-apoptotic and chemotactic ones. Here we report that midkine-deficient mice show a significantly higher survival rate than wild-type mice. The levels of blood urea nitrogen and tubular degeneration and apoptosis were higher in wild-type mice despite the anti-apoptotic activity of midkine. We found that recruitment of neutrophils was more enhanced in wild-type mice, this being consistent with the chemotactic activity of midkine. Midkine expression in wild-type mice persisted for 24 hours, and then dramatically decreased. Preadministration of midkine anti-sense oligodeoxyribonucleotide to wild-type mice suppressed midkine expression, and consequently neutrophil infiltration. It is of note that neutrophil infiltration, apoptosis, and elevation of blood urea nitrogen became conspicuous sequentially, namely 1, 2, and 3 days after cisplatin administration, respectively. These findings suggest that early molecular events involving midkine induce inflammatory response and their circuits eventually enhance the death of the proximal tubule epithelial cells. The results indicate the crucial role of inflammation in cisplatin-induced renal damage, and provide a candidate molecular target for its prevention.

Linking JNK signaling to NF-kappaB: a key to survival

In addition to marshalling immune and inflammatory responses, transcription factors of the NF-kappaB family control cell survival. This control is crucial to a wide range of biological processes, including B and T lymphopoiesis, adaptive immunity, oncogenesis and cancer chemoresistance. During an inflammatory response, NF-kappaB activation antagonizes apoptosis induced by tumor necrosis factor (TNF)-alpha, a protective activity that involves suppression of the Jun N-terminal kinase (JNK) cascade. This suppression can involve upregulation of the Gadd45-family member Gadd45beta/Myd118, which associates with the JNK kinase MKK7/JNKK2 and blocks its catalytic activity. Upregulation of XIAP, A20 and blockers of reactive oxygen species (ROS) appear to be important additional means by which NF-kappaB blunts JNK signaling. These recent findings might open up entirely new avenues for therapeutic intervention in chronic inflammatory diseases and certain cancers; indeed, the Gadd45beta-MKK7 interaction might be a key target for such intervention.

N-acetylcysteine reduces contrast-associated nephropathy but not clinical events during long-term follow-up

BACKGROUND

Contrast-associated nephropathy (CAN) is associated with increased morbidity and mortality following percutaneous coronary intervention (PCI). N-acetylcysteine (NAC) has been shown to reduce the risk of nephropathy; however, the impact of NAC on long-term clinical outcomes has not been assessed.

METHODS

This randomized, double-blind, placebo-controlled trial enrolled 180 patients with moderate renal dysfunction undergoing PCI or coronary angiography with a high likelihood of ad hoc PCI; 171 patients completed the clinical follow-up. Patients received oral NAC (2000 mg/dose, n = 95) or placebo (n = 85) twice a day for 3 doses if randomized the night prior to the procedure, and 2 doses if randomized the day of the procedure. The primary end point was the incidence of a > or =25% increase in serum creatinine level 48 to 72 hours after PCI. Secondary end points were the inhospital incidence of death, nonfatal myocardial infarction, or urgent dialysis, and the 9-month incidence of death, nonfatal myocardial infarction, need for dialysis, or repeat hospitalization for cardiac reasons.

RESULTS

CAN occurred in 9.6% of patients assigned to NAC and 22.2% of patients assigned to placebo (P =.04); 1 patient receiving NAC required urgent dialysis. The inhospital composite end point occurred in 7 (7.4%) NAC-treated and 3 (3.5%) placebo-treated patients, P = NS. At 9 months, the composite end point occurred in 23 (24.2%) NAC-treated patients and 18 (21.2%) placebo-treated, P = NS.

CONCLUSION

Although high-dose NAC prevented periprocedural CAN, this benefit did not translate into a decrease in adverse outcomes over 9 months. Further studies to determine the clinical utility of this drug are required.

Inflammatory cytokines in acute renal failure

A growing body of evidence indicates that inflammatory mechanisms contribute to toxin-induced acute renal failure as well as ischemia/reperfusion injury. A role for tumor necrosis factor-alpha (TNF-alpha) in mediating the inflammatory injury in cisplatin-induced acute renal failure has recently been established. Cisplatin induces the expression of TNF-alpha and TNF receptor subtype 2 (TNFR2) within the kidney. Genetic deletion of either TNF-alpha or TNFR2 substantially reduces cisplatin-induced renal failure and also necrosis and apoptosis within the kidney. Studies will be required to determine if pharmacologic inhibition of TNF-alpha might reduce cisplatin-induced renal failure in humans.

Polymorphism of immunomodulatory cytokine genes: implications in acute renal failure

Experimental studies have incriminated cytokines and other immunoregulatory molecules as important mediators of tissue injury in acute renal failure (ARF). The relative importance of genetic factors, e.g. polymorphisms involving cytokine genes, in influencing susceptibility to and severity of ARF is unknown. This review summarizes the existing experimental and clinical studies supporting the role of inflammation in ARF, and critically examines human studies that have examined polymorphism of two critical cytokine genes, tumor necrosis factor-alpha and interleukin-10, as potential determinants of susceptibility to and severity of acute infectious and inflammatory diseases. Conclusions are drawn on the application of genetic epidemiology to the field of ARF and the rationale for further research on the role of genetic markers in ARF.

Identification of neutrophil gelatinase-associated lipocalin as a novel early urinary biomarker for ischemic renal injury

Acute renal failure (ARF) secondary to ischemic injury remains a common and potentially devastating problem. A transcriptome-wide interrogation strategy was used to identify renal genes that are induced very early after renal ischemia, whose protein products might serve as novel biomarkers for ARF. Seven genes that are upregulated >10-fold were identified, one of which (Cyr61) has recently been reported to be induced after renal ischemia. Unexpectedly, the induction of the other six transcripts was novel to the ARF field. In this study, one of these previously unrecognized genes was further characterized, namely neutrophil gelatinase-associated lipocalin (NGAL), because it is a small secreted polypeptide that is protease resistant and consequently might be readily detected in the urine. The marked upregulation of NGAL mRNA and protein levels in the early postischemic mouse kidney was confirmed. NGAL protein expression was detected predominantly in proliferating cell nuclear antigen-positive proximal tubule cells, in a punctate cytoplasmic distribution that co-localized with markers of late endosomes. NGAL was easily detected in the urine in the very first urine output after ischemia in both mouse and rat models of ARF. The appearance of NGAL in the urine was related to the dose and duration of renal ischemia and preceded the appearance of other urinary markers such as N-acetyl-beta-D-glucosaminidase and beta2-microglobulin. The origin of NGAL from tubule cells was confirmed in cultured human proximal tubule cells subjected to in vitro ischemic injury, where NGAL mRNA was rapidly induced in the cells and NGAL protein was readily detectable in the culture medium within 1 h of mild ATP depletion. NGAL was also easily detectable in the urine of mice with cisplatin-induced nephrotoxicity, again preceding the appearance of N-acetyl-beta-D-glucosaminidase and beta2-microglobulin. The results indicate that NGAL may represent an early, sensitive, noninvasive urinary biomarker for ischemic and nephrotoxic renal injury.

Megalin mediates renal uptake of heavy metal metallothionein complexes

Although several heavy metal toxins are delivered to the kidney on the carrier protein metallothionein (MT), uncertainty as to how MT enters proximal tubular cells limits treatment strategies. Prompted by reports that MT-I interferes with renal uptake of the megalin ligand β2-microglobulin in conscious rats, we tested the hypothesis that megalin binds MT and mediates its uptake. Three lines of evidence suggest that binding of MT to megalin is critical in renal proximal tubular uptake of MT-bound heavy metals. First, MT binds megalin, but not cubilin, in direct surface plasmon resonance studies. Binding of MT occurs at a single site with a Kd∼10−4and, as with other megalin ligands, depends on divalent cations. Second, antisera and various known megalin ligands inhibit the uptake of fluorescently labeled MT in model cell systems. Anti-megalin antisera, but not control sera, displace >90% bound MT from rat renal brush-border membranes. Megalin ligands including β2-microglobulin and also recombinant MT fragments compete for uptake by megalin-expressing rat yolk sac BN-16 cells. Third, megalin and fluorescently labeled MT colocalize in BN-16 cells, as shown by fluorescent microscopic techniques. Follow-up surface plasmon resonance and flow cytometry studies using overlapping MT peptides and recombinant MT fragments identify the hinge SCKKSCC region of MT as a critical site for megalin binding. These findings suggest that disruption of the SCKKSCC motif can inhibit proximal tubular MT uptake and thereby eliminate much of the renal accumulation and toxicity of heavy metals such as cadmium, gold, copper, and cisplatinum.

Role of p53 in cisplatin-induced tubular cell apoptosis: dependence on p53 transcriptional activity

Tubular damage by cisplatin leads to acute renal failure, which limits its use in cancer therapy. In tubular cells, a primary target for cisplatin is presumably the genomic DNA. However, the pathway relaying the signals of DNA damage to tubular cell death is unclear. In response to DNA damage, the tumor suppressor gene p53 is induced and is implicated in subsequent DNA repair and cell death by apoptosis. The current study was designed to examine the role of p53 in cisplatin-induced apoptosis in cultured rat kidney proximal tubular cells. Cisplatin at 20 microM induced apoptosis in approximately 70% of cells, which was partially suppressed by carbobenzoxy-Val-Ala-Asp-fluoromethyl ketone (VAD), a general caspase inhibitor. Of interest, cisplatin-induced apoptosis was also suppressed by pifithrin-alpha, a pharmacological inhibitor of p53. Cisplatin-induced caspase activation was completely inhibited by VAD, but only partially by pifithrin-alpha. Early during cisplatin treatment, p53 was phosphorylated and upregulated. The p53 activation was blocked by pifithrin-alpha, but not by VAD. Bcl-2 expression abolished cisplatin-induced apoptosis without blocking p53 phosphorylation or induction. The results suggest that p53 activation might be an early signal for apoptosis during cisplatin treatment. To further determine the role of p53, tubular cells were stably transfected with a dominant-negative mutant of p53 with diminished transcriptional activity. Expression of the mutant attenuated cisplatin-induced apoptosis and caspase activation. In conclusion, the results support an important role for p53 in cisplatin-induced apoptosis in renal tubular cells. p53 May regulate apoptosis through the transcription of apoptotic genes.

Ethyl pyruvate decreases sepsis-induced acute renal failure and multiple organ damage in aged mice

BACKGROUND

Sepsis is a common cause of acute renal failure (ARF). The incidence of sepsis increases dramatically after 50 years of age; however, most ARF studies are performed in young mice.

METHODS

We performed two common sepsis models, lipopolysaccharide (LPS) administration and cecal ligation puncture (CLP) in aged mice. We developed a fully treated CLP model in aged mice by treating mice with fluid resuscitation and antibiotics.

RESULTS

LPS induced renal injury in aged but not young mice. However, volume resuscitation starting within 6 hours decreased renal injury. We then used this fluid resuscitation scheme, along with antibiotics, to develop a fully treated CLP model in aged mice. Mice subjected to CLP developed functional and histologic ARF and multiple organ damage. Treatment with ethyl pyruvate, even when started 12 hours after surgery, decreased serum creatinine, tubular damage, and multiple organ injury at 24 hours. Ethyl pyruvate decreased plasma tumor necrosis factor-alpha (TNF-alpha), and kidney mRNA for TNF alpha, tissue factor, and plasminogen activator inhibitor-1 (PAI-1), and increased mRNA for urokinase-like plasminogen activator.

CONCLUSION

CLP in aged mice causes functional and histologic changes consistent with human ARF. A single dose of ethyl pyruvate inhibits renal and multiple organ damage, and is still effective when given 12 hours after surgery.

Neutrophil gelatinase-associated lipocalin: a novel early urinary biomarker for cisplatin nephrotoxicity

BACKGROUND

Cisplatin is one of the most widely used chemotherapeutic agents, but the risk of nephrotoxicity frequently hinders the use of higher doses to maximize its antineoplastic effects. The lack of early biomarkers has impaired our ability to initiate potential therapeutic or preventive interventions in cisplatin nephrotoxicity in a timely manner. In this study, we have explored the expression and urinary excretion of neutrophil gelatinase-associated lipocalin (NGAL) in a mouse model of cisplatin-induced nephrotoxic injury.

METHODS

Mice were subjected to intraperitoneal injections of 20 mg/kg (high dose) or 5 mg/kg (low dose) cisplatin. The expression of NGAL was measured in the kidney and urine by Western analysis and immunofluorescence, and compared to changes in serum creatinine and urinary N-acetyl-beta-D-glucosaminidase (NAG).

RESULTS

Cisplatin resulted in tubule cell necrosis and apoptosis following the high dose, but not the low dose. By Western analysis, NGAL protein was rapidly induced in the kidney within 3 h of high-dose cisplatin. By immunofluorescence, NGAL was induced predominantly in proximal tubule cells in a punctate cytoplasmic distribution, reminiscent of a secreted protein. NGAL was easily detected in the urine by Western analysis within 3 h of cisplatin administration in a dose- and duration-dependent manner. By comparison, changes in urinary NAG or serum creatinine were not evident until 96 h after cisplatin. Using defined concentrations of purified recombinant NGAL, urinary NGAL excretion following cisplatin administration was quantified to be in the 20-80 ng/ml range.

CONCLUSION

The results indicate that NGAL represents an early and quantitative urinary biomarker for cisplatin nephrotoxicity.

The story so far: Molecular regulation of the heme oxygenase-1 gene in renal injury

Heme oxygenases (HOs) catalyze the rate-limiting step in heme degradation, resulting in the formation of iron, carbon monoxide, and biliverdin, the latter of which is subsequently converted to bilirubin by biliverdin reductase. Recent attention has focused on the biological effects of product(s) of this enzymatic reaction, which have important antioxidant, anti-inflammatory, and cytoprotective functions. Two major isoforms of the HO enzyme have been described: an inducible isoform, HO-1, and a constitutively expressed isoform, HO-2. A third isoform, HO-3, closely related to HO-2, has also been described. Several stimuli implicated in the pathogenesis of renal injury, such as heme, nitric oxide, growth factors, angiotensin II, cytokines, and nephrotoxins, induce HO-1. Induction of HO-1 occurs as an adaptive and beneficial response to these stimuli, as demonstrated by studies in renal and non-renal disease states. This review will focus on the molecular regulation of the HO-1 gene in renal injury and will highlight the interspecies differences, predominantly between the rodent and human HO-1 genes.

Molecular response to cytotoxic injury: role of inflammation, MAP kinases, and endoplasmic reticulum stress response

Nephrotoxicants have varied direct and indirect effects on the vasculature, tubules, and interstitium of the kidney. In most cases the molecular components of the toxic insult are poorly understood. In this review some common themes of injury, repair, and adaptive protective responses that represent characteristic responses of the cells and kidney tissue that transcend the specifics of a particular toxin are presented. Particular attention is paid to the vascular and inflammatory aspects of nephrotoxicity as well as the activation of the MAP kinase families and the endoplasmic reticulum stress response by the tubular epithelial cell.

Role of caspases in renal tubular epithelial cell injury

The regulation of cell death has been investigated in a number of clinical disorders including renal ischemic and toxic acute renal failure. Caspases play a crucial role in the execution or final phase of cell death by cleaving and inactivating various structural and functional intracellular proteins that are essential for cell survival and proliferation. Evidence is now emerging to implicate the caspase pathway in a variety of renal diseases including the pathogenesis of acute renal failure. Among the 14 known members of the caspase family thus far identified several executioner caspases including caspases-3, -6, and -7 and the proinflammatory caspase including caspase-1 may participate in the final degradation of intracellular proteins. The activation of these caspases is regulated by the receptor- and mitochondrial-mediated cell signaling pathways as well as by the endoplasmic reticulum stress response. While the role of some caspases in renal injury is emerging, the roles of various proinflammatory and other executioner caspases remain to be determined. Although many pro- and anti-apoptotic molecules that act upstream of caspase activation have been identified, their regulation is yet to be determined in the pathogenesis of renal injury. A precise description of caspase-mediated cell death pathway and regulation of caspase activation is, therefore, critical to the understanding of the mechanism of renal injury and to the development of therapeutic targets that prevent renal diseases and preserve renal function.

Cisplatin nephrotoxicity

Cisplatin remains a major antineoplastic drug for the treatment of solid tumors. Its chief dose-limiting side effect is nephrotoxicity, which evolves slowly and predictably after initial and repeated exposure. The kidney accumulates cisplatin to a higher degree than other organs perhaps via mediated transport. Functionally, reduced renal perfusion and a concentrating defect characterize its nephrotoxicity, whereas morphologically necrosis of the terminal portion of the proximal tubule and apoptosis predominantly in the distal nephron characterize its effects on cell fate. Among the earliest reactions of the kidney to cisplatin is the activation of the MAPK cascade and molecular responses typical of the stress response. Repression of genes characteristic of the mature phenotype of the kidney, especially those serving transport function of the kidney, is also prominent. Metabolic responses, cell cycle events and the inflammatory cascade seem to be important determinants of the degree of renal failure induced by cisplatin. Manipulation of these responses may be exploited to reduce its toxicity clinically.

Pentoxifylline suppresses renal tumour necrosis factor-alpha and ameliorates experimental crescentic glomerulonephritis in rats

BACKGROUND

Crescentic glomerulonephritis is a rapidly progressive form of glomerulonephritis, but treatment remains non-specific. The methylxanthine derivative pentoxifylline (PTX) is a clinically available phosphodiesterase inhibitor with anti-inflammatory and immunoregulatory activities. This study examined whether PTX has beneficial effects in a rat model of anti-glomerular basement membrane (GBM) crescentic glomerulonephritis.

METHODS

Experimental crescentic glomerulonephritis was induced in Wistar rats by intravenous injection of rabbit anti-rat GBM serum and treated with either vehicle (phosphate-buffered saline) or PTX (0.1 g/kg/day) intravenously on a daily basis. Groups of six animals were euthanized at days 3, 7, 14 or 28 after induction of disease. Effects of PTX on renal function, histology and expression of cytokines, chemokines and adhesion molecules were determined.

RESULTS

Compared with the vehicle-treated nephritic rats, PTX treatment beginning at the start of the nephritis significantly suppressed mRNA expression of tumour necrosis factor (TNF)-alpha, but not interleukin-1 beta, throughout the course of nephritis. Moreover, PTX decreased renal mRNAs for intercellular adhesion molecule-1 (ICAM-1), monocyte chemoattractant protein-1 (MCP-1), regulated on activation, normal T-cell expressed and secreted (RANTES) and osteopontin (OPN) at all time points examined. These effects were associated with a significant inhibition of macrophage and T-cell infiltration, a reduction of 24-h urinary protein excretion (50-75%, P<0.05), an improvement of histological damage including glomerular crescent formation (60-70%, P<0.01) and a decrease of cortical mRNAs for type I (alpha 1) collagen and fibronectin. The efficacy of PTX could also be seen, though to a lesser extent, in rats with established nephritis.

CONCLUSIONS

PTX is an effective anti-inflammatory and immunomodulatory agent capable of suppressing rat crescentic glomerulonephritis. Inhibition of renal TNF-alpha, ICAM-1, RANTES, MCP-1 and OPN expression may be a mechanism whereby PTX suppresses progressive renal injury in rat crescentic glomerulonephritis.

Salicylate reduces cisplatin nephrotoxicity by inhibition of tumor necrosis factor-α

BACKGROUND

Salicylate was recently shown to provide protection against cisplatin nephrotoxicity in rats. We have demonstrated that enhanced tumor necrosis factor-alpha (TNF-alpha) production mediates, in part, cisplatin nephrotoxicity. The purpose of this study was to determine if the protective effects of salicylate were mediated through inhibition of TNF-alpha in vivo and to explore the mechanism of inhibition in vitro.

METHODS

The effects of treatment with cisplatin alone and in combination with sodium salicylate in mice on renal function, histology, and gene expression were determined. The effects of cisplatin and salicylate on TNF-alpha expression, nuclear factor kappa B (NF-kappa B) activity, and apoptosis were determined in vitro using cultured murine proximal tubule cells.

RESULTS

Salicylate significantly reduced both the functional and histologic evidence of cisplatin renal injury. Cisplatin increased the renal expression of TNF-alpha, monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule (ICAM)-1, heme oxygenase-1, TNF receptor 1 (TNFR1), and TNF receptor 2 (TNFR2). Treatment with sodium salicylate blunted the increase in TNF-alpha mRNA and also reduced serum TNF-alpha protein levels. Salicylate had little protective effect when administered with cisplatin to TNF-alpha-deficient mice. Cisplatin increased the degradation of I kappa B (I kappa B) in a time-dependent manner and also increased nuclear NF-kappa B binding activity. Salicylate inhibited I kappa B degradation and NF-kappa B binding activity in the presence of cisplatin. In addition, salicylate inhibited the cisplatin induced TNF-alpha mRNA increase in mouse proximal tubule epithelial (TKPT) cells.

CONCLUSION

These results indicate that salicylate acts via inhibition of TNF-alpha production to reduce cisplatin nephrotoxicity. The inhibition of TNF-alpha production may be mediated via stabilization of I kappa B.

Optimal Administration Schedule of Cisplatin for Bladder Tumor With Minimal Induction of Metallothionein

PURPOSE

The metal binding protein metallothionein (MT) confers drug resistance when MT is induced in tumor tissues. Cisplatin is known to induce MT synthesis in tumor tissues, which may lead to drug resistance. We examined whether a difference in the administration schedule of cisplatin affect the efficiency of MT induction.

MATERIALS AND METHODS

Balb/c nude mice were inoculated with NMB-1 human bladder tumor tissues and injected with cisplatin (total dose of 64 micromol/kg) in a single injection or fractioned daily injections. Tumor MT concentration was determined 24 hours after the last injection of cisplatin by mercury binding assay. The effect of pretreatment with ZnCl2 on antitumor activity of cisplatin was examined in NMB-1 bearing mice.

RESULTS

Tumor MT levels increased significantly with the increase in the number of cisplatin injections. Pretreatment of NMB-1 bearing mice with ZnCl2 (200 micromol/kg x 2) caused the same level of MT induction (1.6-fold) as that of fractioned injections of cisplatin (4 x 16 micromol/kg). Pretreatment of NMB-1 bearing mice with ZnCl2 (200 micromol/kg x 2) depressed cisplatin antitumor activity by about 50%.

CONCLUSIONS

The induction of MT to a moderate extent (1.6-fold) in NMB-1 tumor inoculated in mice conferred cisplatin resistance. This level of MT induction can be achieved by fractioned daily injections of cisplatin but not by a single injection. Therefore, it is preferable to administer cisplatin as a single injection rather than as fractioned injections to achieve effective antitumor activity with minimum MT induction.

TNFR2-mediated apoptosis and necrosis in cisplatin-induced acute renal failure

Cisplatin produces acute renal failure in humans and mice. Previous studies have shown that cisplatin upregulates the expression of TNF-alpha in mouse kidney and that inhibition of either the release or action of TNF-alpha protects the kidney from cisplatin-induced nephrotoxicity. In this study, we examined the effect of cisplatin on the expression of TNF receptors TNFR1 and TNFR2 in the kidney and the role of each receptor in mediating cisplatin nephrotoxicity. Injection of cisplatin into C57BL/6 mice led to an upregulation of TNFR1 and TNFR2 mRNA levels in the kidney. The upregulation of TNFR2 but not TNFR1 was blunted in TNF-alpha-deficient mice, indicating ligand-dependent upregulation of TNFR2. To study the roles of each receptor, we administered cisplatin to TNFR1- or TNFR2-deficient mice. TNFR2-deficient mice developed less severe renal dysfunction and showed reduced necrosis and apoptosis and leukocyte infiltration into the kidney compared with either TNFR1-deficient or wild-type mice. Moreover, renal TNF-alpha expression, ICAM-1 expression, and serum TNF-alpha levels were lower in TNFR2-deficient mice compared with wild-type or TNFR1-deficient mice treated with cisplatin. These results indicate that TNFR2 participates in cisplatin-induced renal injury in mice and may play an important role in TNF-alpha-mediated inflammation in the kidney in response to cisplatin.

Tumour necrosis factor alpha: a potential target for the therapy of solid tumours

Tumour necrosis factor alpha (TNFalpha), named for its antitumour properties, was isolated almost 30 years ago. It is a vital member of the multifunctional TNF superfamily and has important roles in immunity and cellular remodelling as well as influencing apoptosis and cell survival. Its central role in inflammation has led to the development of TNFalpha antagonists as effective therapies for rheumatoid arthritis and inflammatory bowel disease. In this review, we discuss the evidence which has accumulated during the past decade that implicates TNFalpha in inflammatory pathways that increase tumorigenesis. There is convincing evidence that under specific conditions TNFalpha is a tumour promoter and helps to produce the toxic effects associated with conventional cancer therapy, such as the cytokine release syndrome and cisplatin-induced nephrotoxicity. Several trials have been set up to investigate the role of TNFalpha antagonists in cancer. It is hoped that these agents inhibit the neoplastic process either alone or in combination with other agents, and ameliorate the side effects of cancer therapy.

A novel free radical scavenger, edarabone, protects against cisplatin-induced acute renal damage in vitro and in vivo

Accumulating evidence suggests that enhanced peroxidative damage caused by reactive oxygen species (ROS) may contribute to the pathogenesis of cisplatin-induced acute renal failure. Nevertheless, little is known about the involvement of oxygen radicals in cisplatin nephropathy. In this study, we investigated the effects of a novel free radical scavenger, 3-methyl-1-phenyl-pyrazolin-5-one (MCI-186; edarabone), on murine proximal tubular cell (PTC) damage induced by exposure to cisplatin in vitro and on renal function in an in vivo model of cisplatin-induced acute renal failure. Edarabone inhibited cisplatin-induced (40 microM, 24 h) cytotoxicity in a concentration-dependent manner (10-5 to 10-3 M). Edarabone also attenuated cisplatin-induced mitochondrial transmembrane potential loss and ROS production of PTCs. In the in vivo study, male Wistar rats were cotreated with cisplatin (5 mg/kg, i.p.) and edarabone (1 or 5 mg/kg, i.v.). Effects of edarabone on the kidney were examined 5 days after treatment. Cisplatin resulted in renal dysfunction, renal tubular damage, mitochondrial damage (assayed by histochemical staining for respiratory chain complex IV), renal protein oxidation (examined by Western blot analysis using a specific antibody for carbonyl group-containing proteins), and tubular apoptosis (determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling staining). The above changes were attenuated by edarabone treatment. Thus, edarabone exhibited cytoprotective effects in PTCs and renoprotective effects against cisplatin. Our findings suggest that ROS, in particular hydroxyl radicals, are involved in cisplatin nephropathy and that edarabone may be potentially useful in protecting the kidneys and prevention of acute renal failure.