The impact of p53 on aristolochic acid I-induced nephrotoxicity and DNA damage in vivo and in vitro.

Exposure to aristolochic acid (AA) is associated with human nephropathy and urothelial cancer. The tumour suppressor TP53 is a critical gene in carcinogenesis and frequently mutated in AA-induced urothelial tumours. We investigated the impact of p53 on AAI-induced nephrotoxicity and DNA damage in vivo by treating Trp53(+/+), Trp53(+/-) and Trp53(-/-) mice with 3.5 mg/kg body weight (bw) AAI daily for 2 or 6 days. Renal histopathology showed a gradient of intensity in proximal tubular injury from Trp53(+/+) to Trp53(-/-) mice, especially after 6 days. The observed renal injury was supported by nuclear magnetic resonance (NMR)-based metabonomic measurements, where a consistent Trp53 genotype-dependent trend was observed for urinary metabolites that indicate aminoaciduria (i.e. alanine), lactic aciduria (i.e. lactate) and glycosuria (i.e. glucose). However, Trp53 genotype had no impact on AAI-DNA adduct levels, as measured by 32P-postlabelling, in either target (kidney and bladder) or non-target (liver) tissues, indicating that the underlying mechanisms of p53-related AAI-induced nephrotoxicity cannot be explained by differences in AAI genotoxicity. Performing gas chromatography-mass spectrometry (GC-MS) on kidney tissues showed metabolic pathways affected by AAI treatment, but again Trp53 status did not clearly impact on such metabolic profiles. We also cultured primary mouse embryonic fibroblasts (MEFs) derived from Trp53(+/+), Trp53(+/-) and Trp53(-/-) mice and exposed them to AAI in vitro (50 µM for up to 48 h). We found that Trp53 genotype impacted on the expression of NAD(P)H:quinone oxidoreductase (Nqo1), a key enzyme involved in AAI bioactivation. Nqo1 induction was highest in Trp53(+/+) MEFs and lowest in Trp53(-/-) MEFs; and it correlated with AAI-DNA adduct formation, with lowest adduct levels being observed in AAI-exposed Trp53(-/-) MEFs. Overall, our results clearly demonstrate that p53 status impacts on AAI-induced renal injury, but the underlying mechanism(s) involved remain to be further explored. Despite the impact of p53 on AAI bioactivation and DNA damage in vitro, such effects were not observed in vivo.

Balkan Endemic Nephropathy and the Causative Role of Aristolochic Acid.

Balkan endemic nephropathy is a chronic tubulointerstitial disease with insidious onset, slowly progressing to end-stage renal disease and frequently associated with urothelial carcinoma of the upper urinary tract (UTUC). It was described in South-East Europe at the Balkan peninsula in rural areas around tributaries of the Danube River. After decades of intensive investigation, the causative factor was identified as the environmental phytotoxin aristolochic acid (AA) contained in Aristolochia clematitis, a common plant growing in wheat fields that was ingested through home-baked bread. AA initially was involved in the outbreak of cases of rapidly progressive renal fibrosis reported in Belgium after intake of root extracts of Aristolochia fangchi imported from China. A high prevalence of UTUC was found in these patients. The common molecular link between Balkan and Belgian nephropathy cases was the detection of aristolactam-DNA adducts in renal tissue and UTUC. These adducts are not only biomarkers of prior exposure to AA, but they also trigger urothelial malignancy by inducing specific mutations (A:T to T:A transversion) in critical genes of carcinogenesis, including the tumor-suppressor TP53. Such mutational signatures are found in other cases worldwide, particularly in Taiwan, highlighting the general public health issue of AA exposure by traditional phytotherapies.

Early detection of acute cisplatin nephrotoxicity: interest of urinary monitoring of proximal tubular biomarkers.

BACKGROUND: Renal toxicity induced by cisplatin (CisPt) is a clinical issue in patients with or without chronic kidney disease (CKD). Proximal tubular injury can result in acute kidney injury (AKI), which may compromise the course of chemotherapy and the prognosis. The purpose of this study was to investigate the time course of urinary markers of acute tubulotoxicity and to assess the usefulness of such monitoring in a routine clinical setting. METHODS: This work is an open prospective pilot study carried out among 23 patients receiving a platinum-based chemotherapy. Individual comorbidities, plasma parameters of kidney function (urea, creatinine) and estimated glomerular filtration rate were registered. Urinary excretion of leucine aminopeptidase, neutrophil gelatinase-associated lipocalin, cystatin C, liver fatty acid-binding protein and interleukin-18 were monitored during successive chemotherapy cycles. Episodes of AKI were identified according to KDIGO (Kidney Disease Improving Global Outcomes) 2012 guidelines. RESULTS: A total of 28 patients were recruited; among them 23 agreed to be part of the study, of whom 18 received CisPt and 5 carbo- or oxaliplatin. Of the 18 CisPt patients, 12 had a preexisting CKD. Sixteen AKI episodes were observed in 13 patients receiving CisPt with a pejorative evolution in seven cases (partial recovery of the renal function); a transient but dramatic increase in urinary biomarkers was observed 3 h after chemotherapy initiation, whereas plasma creatinine rise appeared 72 h after the end of CisPt treatment. Identified precipitating factors included: dehydration due to lack of fluid intake or diuretic use, exposure to high CisPt doses, regular use of nonsteroidal anti-inflammatory drugs and/or iodinated contrast agents and sepsis. CONCLUSION: Even if numerous precipitating factors could be avoided, the monitoring of urinary markers seemed helpful for the early detection of subclinical AKI induced during CisPt chemotherapy.

Severe myoglobinuric acute kidney injury in a kidney recipient: rapid recovery after hemodialysis with the super high-flux membrane Theralite®â€©.

Myoglobinuric acute kidney injury (AKI) is a severe condition requiring early therapeutic strategies. Early recognition and treatment are crucial to reduce morbidity and mortality rate. Here, we report a kidney recipient with severe rhabdomyolysis and AKI secondary to parvovirus B19 infection. Initiation of hemodialysis with the super high-flux filter Theralite® (Gambro, cut-off 45 kDa, 2.1 m2) resulted in the clearance of myoglobin from 61 to 71% after 3 hours. Elimination rates of IL-6 and ß2-microglobulin were ~ 30 - 64% and 55 - 71% after 3 hours, respectively. Renal graft function rapidly recovered. The place of this effective but expensive procedure still needs to be defined and validated in high-risk patients.
.

Bacillus Calmette-Guerin therapy in non-muscle-invasive bladder carcinoma after renal transplantation for end-stage aristolochic acid nephropathy.

Intravesical instillation of bacillus Calmette-Guerin (BCG) is the treatment of choice for non-muscle-invasive bladder cancer (NMIBC) of high grade and/or carcinoma in situ. This study evaluated the feasibility, efficacy, and tolerance of BCG instillations in eight kidney recipients for end-stage aristolochic acid nephropathy (AAN), a condition at high risk of urothelial carcinoma, and diagnosed for NMIBC. Five of them had relapsed after mitomycin C treatment. Tolerance to BCG was evaluated clinically and regular follow-up with fluorescence cystoscopy was performed along with renal graft function monitoring. Immunosuppression doses were adjusted and prophylactic anti-tuberculous treatment given to reduce risks of graft rejection and infection. After a mean follow-up period of 50 months, seven of the eight patients are free of relapse and kidney graft function remained unchanged. Tolerance was good, except for one episode of fever and one early discontinuation because of subjective discomfort. No systemic tuberculous infection was observed. This is the first clinical observation of successful BCG therapy for NMIBC in patients given transplant for end-stage AAN. Under standardized conditions, immunotherapy based on intravesical BCG is feasible, effective, and well tolerated in renal transplantation.

Exceptionally long-term persistence of DNA adducts formed by carcinogenic aristolochic acid I in renal tissue from patients with aristolochic acid nephropathy.

Aristolochic acid (AA) causes aristolochic acid nephropathy (AAN), first described in women in Belgium accidently prescribed Aristolochia fangchi in a slimming treatment, and also Balkan endemic nephropathy (BEN), through probable dietary contamination with Aristolochia clematitis seeds. Both nephropathies have a high risk of urothelial cancer, with AA being the causative agent. In tissues of AAN and BEN patients, a distinct DNA adduct, 7-(deoxyadenosin-N6-yl)-aristolactam I (dA-AAI), has been detected. DNA adducts can be removed through DNA repair, they can result in mutations through erroneous DNA replication or they can cause cell death. The dA-AAI adduct induces AT to TA transversions in the tumor-suppressor TP53 gene in experimental systems, matching TP53 mutations observed in urothelial tumors from AAN cancer cases. Using thin-layer chromatography 32P-postlabeling and mass spectrometric analysis we report the detection of dA-AAI in renal DNA from 11 Belgian AAN patients over 20 years after exposure to AA had ceased. Our results showed that dA-AAI is an established biomarker of AA exposure, and that this biomarker can be demonstrated to be persistent decades after a distinct AA exposure. Further, the persistence of dA-AAI adducts appears to be a critical determinant for the AA mutational fingerprint frequently found in oncogenes and tumor suppressor genes recently identified by whole genome sequencing of AA-associated urothelial tumors. The potential for exposure to AA worldwide is high; the unprecedented long-term persistence of dA-AAI provides a useful long-term biomarker of exposure and attests to the role of AA in human urothelial malignancy.

The epidemiology, diagnosis, and management of aristolochic acid nephropathy: a narrative review.

It has been 20 years since the first description of a rapidly progressive renal disease that is associated with the consumption of Chinese herbs containing aristolochic acid (AA) and is now termed aristolochic acid nephropathy (AAN). Recent data have shown that AA is also the primary causative agent in Balkan endemic nephropathy and associated urothelial cancer. Aristolochic acid nephropathy is associated with a high long-term risk for renal failure and urothelial cancer, and the potential worldwide population exposure is enormous. This evidence-based review of the diagnostic approach to and management of AAN draws on the authors' experience with the largest and longest-studied combined cohort of patients with this condition. It is hoped that a better understanding of the importance of this underrecognized and severe condition will improve epidemiologic, preventive, and therapeutic strategies to reduce the global burden of this disease.

Sarcoma-like pyogenic granuloma of the thumb and respiratory restrictive syndrome in a non-compliant hemodialysis patient.

Pyogenic granuloma is a benign vascular tumor of the skin or mucosae usually observed after irritative processes. We report the case of a non-compliant hemodialysis patient with severe hyperparathyroidism who rapidly developed growing pyogenic granuloma of the distal part of the left thumb. This tumor mimicked sarcoma and caused recurrent bleeding during hemodialysis sessions. Hand radiograph revealed an osteolytic lesion compatible with a brown tumor. Among other brown tumors, several of those found in the ribs were responsible of a severe respiratory restrictive deficit. This report highlights the difficulty to choose the adequate treatment of severe hyperparathyroidism, and discusses the benefit/risk balance of performing parathyroidectomy.

Probenecid prevents acute tubular necrosis in a mouse model of aristolochic acid nephropathy.

Experimental aristolochic acid nephropathy is characterized by early tubulointerstitial injury followed by fibrosis, reproducing chronic lesions seen in humans. In vitro, probenecid inhibits aristolochic acid entry through organic anion transporters, reduces specific aristolochic acid-DNA adduct formation, and preserves cellular viability. To test this in vivo, we used a mouse model of aristolochic acid nephropathy displaying severe tubulointerstitial injuries consisting of proximal tubular epithelial cell necrosis associated to transient acute kidney injury followed by mononuclear cell infiltration, tubular atrophy, and interstitial fibrosis. Treatment with probenecid prevented increased plasma creatinine and tubulointerstitial injuries, and reduced both the extent and the severity of ultrastructural lesions induced by aristolochic acid, such as the loss of brush border, mitochondrial edema, and the disappearance of mitochondrial crests. Further, the number of proliferating cell nuclear antigen-positive cells and total aristolochic acid-DNA adducts were significantly reduced in mice receiving aristolochic acid plus probenecid compared with mice treated with aristolochic acid alone. Thus, we establish the nephroprotective effect of probenecid, an inhibitor of organic acid transporters, in vivo toward acute proximal tubular epithelial cell toxicity in a mouse model of aristolochic acid nephropathy.

Azathioprine as successful maintenance therapy in IgG4-related tubulointerstitial nephritis.

A 65-year-old man presented with a progressive increase in plasma creatinine (PCr). Two years before, diffusion-weighted magnetic resonance imaging had revealed a relapse of immunoglobulin G4 (IgG4)-related autoimmune pancreatitis (AIP) associated with sclerosing cholangitis. Bilateral hypointense renal cortical nodules were also described. Kidney biopsy showed patchy disappearance of tubules, sparse interstitial fibrosis and IgG4+ plasma cells (>30 per high power field) leading to the diagnosis of IgG4-related tubulointerstitial nephritis (TIN). Despite methylprednisolone, PCr and serum IgG4 levels remained elevated. Starting azathioprine (AZA) normalized IgG4 levels, which elicited corticosteroid withdrawal after 17 months. One year later, renal function remains stable. Our clinical observation underlines the importance of biological and radiological long-term follow-up of patients with previous AIP in order to early detect IgG4-related renal involvement. Corticosteroids are the first choice, but in the case of adverse effects or partial remission, AZA could be a useful and safe alternative therapy.

Gene expression changes induced by the human carcinogen aristolochic acid I in renal and hepatic tissue of mice.

Aristolochic acid (AA) is the causative agent of urothelial tumors associated with AA nephropathy and is also implicated in the development of Balkan endemic nephropathy-associated urothelial tumors. These tumors contain AA-characteristic TP53 mutations. We examined gene expression changes in Hupki (human TP53 knock-in) mice after treatment with aristolochic acid I (AAI) by gavage (5 mg/kg body weight). After 3, 12 and 21 days of treatment gene expression profiles were investigated using Agilent Whole Mouse 44K Genome Oligo Array. Expression profiles were significantly altered by AAI treatment in both target (kidney) and nontarget (liver) tissue. Renal pathology and DNA adduct analysis confirmed kidney as the target tissue of AAI-induced toxicity. Gene ontology for functional analysis revealed that processes related to apoptosis, cell cycle, stress response, immune system, inflammatory response and kidney development were altered in kidney. Canonical pathway analysis indicated Nfκb, aryl hydrocarbon receptor, Tp53 and cell cycle signaling as the most important pathways modulated in kidney. Expression of Nfκb1 and other Nfκb-target genes was confirmed by quantitative real-time PCR (qRT-PCR) and was consistent with the induction of Nfκb1 protein. Myc oncogene, frequently overexpressed in urothelial tumors, was upregulated by AAI on the microarrays and confirmed by qRT-PCR and protein induction. Collectively we found that microarray gene expression analysis is a useful tool to define tissue-specific responses in AAI-induced toxicity. Several genes identified such as TP53, Rb1, Mdm2, Cdkn2a and Myc are frequently affected in human urothelial cancer, and may be valuable prognostic markers in future clinical studies.

Revisiting nephrogenic systemic fibrosis in 6 kidney transplant recipients: a single-center experience.

BACKGROUND: Nephrogenic systemic fibrosis (NSF) is a fibrotic disorder occurring in patients with renal dysfunction. Exposure to gadolinium (Gd)-based contrast agents (GBCAs) during renal impairment is associated with development of NSF. METHODS: A cross-referenced search of kidney transplantation and radiology databases at a single institution revealed the prevalence of NSF in the transplant population. Clinical records and skin biopsy specimens from 6 patients with kidney transplant given a diagnosis of NSF were reviewed to identify contributing factors. RESULTS: Between January 1999 and December 2006, NSF was diagnosed in 6 of 705 patients with kidney transplant (0.9%). Renal function was impaired in all patients. Of 33 patients with kidney transplant exposed to GBCAs, 5 (15.2%) developed NSF. Disease onset ranged from 7 days to 11 months after exposure to GBCAs. All 5 patients exposed to GBCAs who developed NSF were also treated with a beta-blocker and clinical improvement was observed with discontinuation. The sixth case NSF appeared unrelated to Gd, without a known exposure, and testing of tissue via mass spectrometry revealed no Gd. Symptoms of NSF in this patient disappeared after administration of darbepoetin was switched from subcutaneous to intravenous injection. One patient with NSF who manifested the highest Gd level in tissue died 22 months after disease onset. LIMITATIONS: The study represents the retrospective experience of only a single center. CONCLUSIONS: NSF can develop in kidney transplant recipients with altered graft function. In these patients, exposure to GBCAs appears associated with development of NSF. The role of beta-blockers in the course of the disease merits further investigation.

Nephrotic syndrome and renal failure as an unusual presentation of solid tumour.

Glomerular diseases may occur as primary manifestation of cancer, especially in patients older than 60 years. Among glomerulopathies, membranous nephropathy is preferentially associated with respiratory and gastrointestinal tract adenocarcinomas, whereas minimal change disease is most often seen in haematological malignancies. Though breast cancer is one of the most frequent malignancies in women, paraneoplastic glomerular disease is rarely observed. We describe the case of a 79-year-old female patient who presented with nephrotic syndrome and renal failure. Breast cancer was found. Pathological studies of kidney and breast biopsy revealed a minimal change disease and an infiltrating ductal carcinoma, respectively.

Aristolochic acid nephropathy: a worldwide problem.

Aristolochic acid nephropathy (AAN), a progressive renal interstitial fibrosis frequently associated with urothelial malignancies, was initially reported in a Belgian cohort of more than 100 patients after the intake of slimming pills containing a Chinese herb, Aristolochia fangchi. Although botanicals known or suspected to contain aristolochic acid (AA) were no longer permitted in many countries, several AAN cases were regularly observed all around the world. The incidence of AAN is probably much higher than initially thought, especially in Asia and the Balkans. In Asian countries, where traditional medicines are very popular, the complexity of the pharmacopoeia represents a high risk for AAN because of the frequent substitution of the botanical products by AA-containing herbs. In the Balkan regions, the exposure to AA found in flour obtained from wheat contaminated with seeds of Aristolochia clematitis could be responsible for the so-called Balkan-endemic nephropathy. Finally, despite the Food and Drug Administration's warnings concerning the safety of botanical remedies containing AA, these herbs are still sold via the Internet.

Patterns of interstitial inflammation during the evolution of renal injury in experimental aristolochic acid nephropathy.

BACKGROUND: Interstitial inflammation is a prominent feature associated with the severity of renal injury and progressive kidney failure. We utilized an animal model of aristolochic acid (AA)-induced nephropathy (AAN) to assess patterns of infiltration and inflammation during the evolution of tubulointerstitial damage and to relate them to the development of fibrosis. METHODS: Male Wistar rats receiving sc daily AA or vehicle were sacrificed between Days 1 and 35. Infiltrating mononuclear cells were characterized by immunohistochemistry. The kidney infiltrating T lymphocytes were phenotyped by flow cytometry. Urinary levels of Th-1/ Th-2 cytokines, of monocyte chemoattractant protein-1 and of active transforming growth factor-beta (TGF-beta) were measured. Tissue expression of phosphorylated smad 2/3 protein was used to examine the TGF-beta signalling pathway. RESULTS: In AA rats, monocytes/macrophages and T lymphocytes predominantly infiltrated areas of necrotic proximal tubular cells. The coexpressions of ED1 and/or Ki-67/MHCII by infiltrating cells reflected monocyte/macrophage proliferation and their activation, respectively. The accumulation of cytotoxic T lymphocytes was attested by severe signs of CD8+ cell tubulitis. The CD8/E-cadherin costaining confirmed intrarenal homing of CD8+CD103+ cells. Urinary levels of proinflammatory cytokines and of active TGF-beta significantly increased at Days 10 and 35. An early and persistent nuclear overexpression of phosphorylated smad 2/3 protein was detected in tubular and interstitial compartments. CONCLUSION: An early and massive interstitial inflammation characterized by activated monocytes/macrophages and cytotoxic CD8+CD103+ T lymphocytes is demonstrated for the first time during the progression of experimental AAN. The involvement in an interstitial fibrosis onset of active TGF-beta is highly suggested, at least via the psmad 2/3 intracellular signalling pathway.

Aristolochic acid mutagenesis: molecular clues to the aetiology of Balkan endemic nephropathy-associated urothelial cancer.

Balkan endemic nephropathy (BEN) is found in certain rural areas of the Balkans and affects at least 25,000 inhabitants. Of the many hypotheses on BEN, the Aristolochia hypothesis has recently gained ground substantiated by the investigations on aristolochic acid nephropathy (AAN). On both clinical and morphological grounds, AAN is very similar to BEN. That exposure to aristolochic acid (AA) of individuals living in endemic areas through consumption of bread made with flour contaminated with seeds of Aristolochia clematitis is responsible for BEN is an old hypothesis, but one which is fully consistent with the unique epidemiologic features of BEN. Here, we propose an approach to investigate AA-induced mutagenesis in BEN that can provide molecular clues to the aetiology of its associated urothelial cancer. The molecular mechanism of AA-induced carcinogenesis demonstrates a strong association between DNA adduct formation, mutation pattern and tumour development. A clear link between urothelial tumours, p53 mutations and AA exposure should emerge as more tumour DNA from BEN patients from different endemic areas becomes available for mutation analysis. We predict that the observed p53 mutation spectrum will be dominated by AT --> TA transversion mutations as has already been demonstrated in the human p53 gene of immortalized cells after exposure to AAI and urothelial tumours from BEN patients in Croatia. Moreover, the detection of AA-specific DNA adducts in renal tissue of a number of BEN patients and individuals living in areas endemic for BEN in Croatia provides new evidence that chronic exposure to AA is a risk factor for BEN and its associated cancer.