Chinese herb nephropathy is not a (dex)fenfluramine nephropathy but a serotonin nephropathy

Ochratoxin A and aristolochic acid involvement in nephropathies and associated urothelial tract tumours

This review addresses the unresolved aetiology of several nephropathies and associated upper tract tumours diagnosed all over the world, but especially in the Balkan regions. Studies conducted over the last 35 years point to mycotoxins, mainly ochratoxin A (OTA) as the main culprit. Recent theories however have implicated aristolochic acids (AA). The aim of this review is to put forward arguments in favour of the mycotoxin theory and to show the incoherence of the AA theory. It discusses the differences between the epidemiology of Balkan endemic nephropathy (BEN) and aristolochic acid nephropathy (AAN); OTA and AA carcinogenicity; clinical and pathological effects induced by OTA and AA; sources of OTA contamination (food, air, drinking water); OTA- and AA-DNA adduct formation; the role of genetic polymorphisms; and the risk for young children.

Aristolochic acid and 'Chinese herbs nephropathy': a review of the evidence to date

Chinese herbs nephropathy (CHN) is a rapidly progressive interstitial nephropathy reported after the introduction of Chinese herbs in a slimming regimen followed by young Belgian women. It is characterised by early, severe anaemia, mild tubular proteinuria and initially normal arterial blood pressure in half of the patients. Renal histology shows unusual extensive, virtually hypocellular cortical interstitial fibrosis associated with tubular atrophy and global sclerosis of glomeruli decreasing from the outer to the inner cortex. Urothelial malignancy of the upper urinary tract develops subsequently in almost half of the patients. Suspicion that the disease was due to the recent introduction of Chinese herbs in the slimming regimen was reinforced by identification in the slimming pills of the nephrotoxic and carcinogenic aristolochic acid (AA) extracted from species of Aristolochia. This hypothesis was substantiated by the identification of premutagenic AA-DNA adducts in the kidney and ureteric tissues of CHN patients. Finally, induction of the clinical features (interstitial fibrosis and upper urothelial malignancy) typical of CHN in rodents given AA alone removed any doubt on the causal role of this phytotoxin in CHN, now better called aristolochic acid nephropathy (AAN). AAN is not restricted to the Belgian cases. Similar cases have been observed throughout the world, but AA is sometimes incriminated on the basis of the known content of AA in the herbs. The possibility remains that in some individuals in whom AA has not been demonstrated, other phytotoxins might be implicated. Biological and morphological features of AAN are strikingly similar to those reported in another fibrosing interstitial nephropathy of still unknown aetiology, Balkan endemic nephropathy (BEN). Interestingly, AA was incriminated as the cause of BEN many years ago, a hypothesis yet to be fully explored. The intake of AA and the presence of tissular AA-DNA adducts in patients with an unequivocal diagnosis of BEN remains to be demonstrated. The tragic phenomenon of CHN, recognised only 10 years ago, has been at the root of significant research and progress both in nephrology and oncology. It has provided a fascinating opportunity to understand the link between a fibrosing interstitial nephropathy and urothelial carcinoma. It allows the categorisation of interstitial nephritis on the basis of histological findings, of initiating toxic substances and of associated clinical features. Finally, it has led to the withdrawal in several countries of a previously unsuspected carcinogenic and nephrotoxic substance.

Effects of dexfenfluramine on aristolochic acid nephrotoxicity in a rat model for Chinese-herb nephropathy

Chinese-herb nephropathy (CHN) is a progressive renal interstitial fibrosis initially reported after concomitant intake of an anorexigen, (dex)fenfluramine, and a Chinese herb ( Aristolochia fangchi) containing nephrotoxic and carcinogenic aristolochic acid (AA). We thus tested the possible enhancing effect of the active enantiomer dexfenfluramine (DXF) on AA nephrotoxicity in a rat model for CHN. Groups of 12 salt-depleted male Wistar rats received daily subcutaneous injections of 7 mg/kg body weight DXF (DXF group), 7 mg/kg body weight AA (AA group), a combination of the same doses of AA and DXF (AA+DXF group), or vehicle (control group) for up to 35 days. Six animals per group were killed on day 10 and the remaining six on day 35. Renal function was evaluated by determining serum creatinine and urinary leucine aminopeptidase activity. Histological evaluation of kidney samples was performed and tubulointerstitial injuries were semiquantified. The DXF group did not differ from controls for any parameter. Similarly elevated serum creatinine levels, decreased leucine aminopeptidase enzymuria, and renal lesions were observed in the AA and the AA+DXF groups after both 10 and 35 days. The formation of specific AA-DNA adducts in liver and renal tissue samples was assessed by the (32)P-postlabelling method. Specific AA-DNA adduct levels were significantly increased in kidney tissues from AA+DXF rats compared with AA rats. These functional and histological data suggest that DXF does not enhance AA nephrotoxicity in a rat model for CHN. Further investigations are needed to clarify the mechanism by which DXF may enhance AA-DNA adduct formation.

Urothelial carcinoma associated with the use of a Chinese herb (Aristolochia fangchi)

BACKGROUND

Chinese-herb nephropathy is a progressive form of renal fibrosis that develops in some patients who take weight-reducing pills containing Chinese herbs. Because of a manufacturing error, one of the herbs in these pills (Stephania tetrandra) was inadvertently replaced by Aristolochia fangchi, which is nephrotoxic and carcinogenic.

METHODS

The diagnosis of a neoplastic lesion in the native urinary tract of a renal-transplant recipient who had Chinese-herb nephropathy prompted us to propose regular cystoscopic examinations and the prophylactic removal of the native kidneys and ureters in all our patients with end-stage Chinese-herb nephropathy who were being treated with either transplantation or dialysis. Surgical specimens were examined histologically and analyzed for the presence of DNA adducts formed by aristolochic acid. All prescriptions written for Chinese-herb weight-reducing compounds during the period of exposure (1990 to 1992) in these patients were obtained, and the cumulative doses were calculated.

RESULTS

Among 39 patients who agreed to undergo prophylactic surgery, there were 18 cases of urothelial carcinoma (prevalence, 46 percent; 95 percent confidence interval, 29 to 62 percent): 17 cases of carcinoma of the ureter, renal pelvis, or both and 1 papillary bladder tumor. Nineteen of the remaining patients had mild-to-moderate urothelial dysplasia, and two had normal urothelium. All tissue samples analyzed contained aristolochic acid-related DNA adducts. The cumulative dose of aristolochia was a significant risk factor for urothelial carcinoma, with total doses of more than 200 g associated with a higher risk of urothelial carcinoma.

CONCLUSIONS

The prevalence of urothelial carcinoma among patients with end-stage Chinese-herb nephropathy (caused by aristolochia species) is a high.

Rapidly progressive fibrosing interstitial nephritis associated with Chinese herbal drugs

Rapidly progressive fibrosing interstitial nephritis after a slimming regimen containing aristolochic acid has been identified as Chinese herbs nephropathy (CHNP). From 1995 to 1998, we observed 12 Chinese people from different areas of Taiwan who underwent renal biopsy for unexplained renal failure. Medical history gave no clue to the causes of impaired renal function except for the ingestion of traditional Chinese herbs. Although these patients ingested herbal drugs from various sources for different purposes, their renal biopsy samples showed amazingly similar histological findings, with extensive hypocellular interstitial fibrosis and atrophy and loss of tubules in all cases. Glomeruli were apparently intact. They also had similar clinical features, such as normal or mildly elevated blood pressure, early and severe anemia, low-grade proteinuria, glycosuria, and insignificant urinary sediments. Renal function deteriorated rapidly in most patients despite discontinuation of the herbal medicines. Seven patients underwent dialysis, and the remainder experienced slowly progressive renal failure. Bladder carcinoma was found in one patient. Morphologically and clinically, the nephropathy in our patients was similar to CHNP, reported in Belgium. Because of the complexity and unknown types of herbs used in different clinical situations, unidentified phytotoxins other than aristolochic acid might be responsible for this unique disease entity. We conclude that the relation of this nephropathy to the consumption of Chinese herbs is striking. Using uncontrolled herbal remedies carries a high risk for developing interstitial renal fibrosis and urothelial malignancy.