Evaluation of the nephrotoxicity and safety of low-dose aristolochic acid, extending to the use of Xixin (Asurum), by determination of methylglyoxal and d-lactate.

ETHNOPHARMACOLOGICAL RELEVANCE: Most Aristolochiaceae plants are prohibited due to aristolochic acid nephropathy (AAN), except Xixin (Asarum spp.). Xixin contains trace amounts of aristolochic acid (AA) and is widely used in Traditional Chinese Medicine. Methylglyoxal and d-lactate are regarded as biomarkers for nephrotoxicity. AIM OF THE STUDY: The use of Xixin (Asarum spp.) is essential and controversial. This study aimed to evaluate tubulointerstitial injury and interstitial renal fibrosis by determining urinary methylglyoxal and d-lactate after withdrawal of low-dose AA in a chronic mouse model. MATERIALS AND METHODS: C3H/He mice in the AA group (n = 24/group) were given ad libitum access to distilled water containing 3 µg/mL AA (0.5 mg/kg/day) for 56 days and drinking water from days 57 to 84. The severity of tubulointerstitial injury and fibrosis were evaluated using the tubulointerstitial histological score (TIHS) and Masson's trichrome staining. Urinary and serum methylglyoxal were determined by high-performance liquid chromatography (HPLC); urinary d-lactate were determined by column-switching HPLC. RESULTS: After AA withdrawal, serum methylglyoxal in the AA group increased from day 56 (429.4 ± 48.3 µg/L) to 84 (600.2 ± 99.9 µg/L), and peaked on day 70 (878.3 ± 171.8 µg/L; p < 0.05); TIHS and fibrosis exhibited similar patterns. Urinary methylglyoxal was high on day 56 (3.522 ± 1.061 µg), declined by day 70 (1.583 ± 0.437 µg) and increased by day 84 (2.390 ± 0.130 µg). Moreover, urinary d-lactate was elevated on day 56 (82.10 ± 18.80 µg) and higher from day 70 (201.10 ± 90.82 µg) to 84 (193.28 ± 61.32 µg). CONCLUSIONS: Methylglyoxal is induced after AA-induced tubulointerstitial injury, so methylglyoxal excretion and metabolism may be a detoxification and repair strategy. A low cumulative AA dose is the key factor that limits tubulointerstitial injury and helps to repair. Thus, AA-containing herbs, especially Xixin, should be used at low doses for short durations (less than one month).

Utilizing methylglyoxal and D-lactate in urine to evaluate saikosaponin C treatment in mice with accelerated nephrotoxic serum nephritis.

The relationship between methylglyoxal (MGO) and D-lactate during saikosaponin C (SSC) treatment of mice with accelerated nephrotoxic serum (NTS) nephritis was investigated. NTS nephritis was induced by administration of anti-basement membrane antibodies to C57BL/6 mice and three dosages of SSC were administered for 14 days. Proteinuria, blood urea nitrogen, serum creatinine, renal histology, urinary MGO and d-lactate changes were examined. Compared to the NTS control group, the middle dosage (10 mg/kg/day) of SSC significantly alleviated the development of nephritis based on urine protein measurements (34.40 ± 6.85 vs. 17.33 ± 4.79 mg/day, p<0.05). Pathological observation of the glomerular basement membrane (GBM) revealed monocyte infiltration, hypertrophy, and crescents were alleviated, and injury scoring also showed improved efficacy for the middle dose of SSC during nephritis (7.92 ± 1.37 vs. 3.50 ± 1.14, p<0.05). Moreover, the significant decreases in urinary levels of MGO (24.71 ± 3.46 vs. 16.72 ± 2.36 µg/mg, p<0.05) and D-lactate (0.31 ± 0.04 vs. 0.23 ± 0.02 µmol/mg, p<0.05) were consistent with the biochemical and pathological examinations. This study demonstrates that MGO and D-lactate may reflect the extent of damage and the efficacy of SSC in NTS nephritis; further studies are required to enable clinical application.

Determination of temporal changes in serum and urinary lactate and 3-hydroxybutyrate enantiomers in mice with nephrotoxic serum nephritis by multi-dimensional HPLC.

Nephrotoxic serum (NTS) nephritis occurs in three stages: inflammation, early kidney damage, and severe kidney damage. We quantified the temporal changes in the enantiomers of lactate (LA) and 3-hydroxybutyrate (3HB) in serum and urine during the progression of autoimmune kidney damage in mice with NTS nephritis. Two-dimensional and three-dimensional HPLC were used to quantify the enantiomers. The serum and urinary levels of LA and 3HB enantiomers significantly changed during the progression of NTS nephritis. Specifically, d-LA was significantly higher in the serum (131.8 ±â€¯30.6, 123.7 ±â€¯27.2, 109.3 ±â€¯15.6 vs. 51.2 ±â€¯7.5 µM; p < 0.05) and urine (222.2 ± 34.8, 197.4 ± 53.9, 214.8 ± 68.9 vs. 100.8 ± 37.7 µmol/g creatinine; p < 0.05) of the week 0 (W0), week 1 (W1), and week 2 (W2) groups than the normal group. The l-3HB/d-3HB ratio was significantly lower in the W0, W1, and W2 groups than the normal group in serum (0.0362 ±â€¯0.0082, 0.0346 ±â€¯0.0065, 0.0323 ±â€¯0.0033 vs. 0.0602 ±â€¯0.0214; p < 0.05) and urine (0.0591 ± 0.0304, 0.1524 ± 0.0365, 0.1232 ± 0.1066 vs. 0.3273 ± 0.1394; p < 0.05). The changes in serum and urinary d-LA and l-3HB/d-3HB ratios were stable before severe kidney damage. In conclusion, we successfully determined the levels of LA and 3HB enantiomers in NTS nephritis by HPLC. Serum and urinary d-LA contents and l-3HB/d-3HB ratios may have potential as biomarkers of early autoimmune kidney injury.