LAUSR

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 ± 30.6, 123.7 ± 27.2, 109.3 ± 15.6 vs. 51.2 ± 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 ± 0.0082, 0.0346 ± 0.0065, 0.0323 ± 0.0033 vs. 0.0602 ± 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.