Comparison of the course of biomarker changes and kidney injury in a rat model of drug-induced acute kidney injury.

OBJECTIVE: To aid in evaluating the performance of biomarkers, we measured kidney injury biomarkers in rat models of drug-induced acute kidney injury. METHODS AND RESULTS: Rats were treated with site-specific nephrotoxins, puromycin, gentamicin, cisplatin, or 2-bromoethylamine. Fifteen biomarkers (ß-2-microglobulin, calbindin, clusterin, cystatin-C, KIM-1, GST-α, GST-µ, NGAL, osteopontin, EGF, TIMP-1, VEGF, albumin, RPA-1, and urinary total protein) were examined in comparison with BUN, serum creatinine, and NAG. Some biomarkers, which were different depending in each nephrotoxin, showed ability to detect the prodromal stage of drug-induced kidney injury. Characteristic changing patterns of biomarkers were also found depending on the specific lesion site in the kidney. CONCLUSION: These data suggested that establishment of a suitable biomarker panel would facilitate detection of site-specific kidney injury with high sensitivity.

Meso scale discovery and luminex comparative analysis of calbindin D28K.

The sensitivity of different renal regions to xenobiotics requires the development of a multiplex immunoassay for the simultaneous analysis of kidney biomarkers. Calbindin D28K is a distal tubule-specific protein that can be detected in urine under pathological conditions. In this study, a pair of anti-calbindin D28K antibodies was used in an immunoassay for the detection of calbindin D28K expression in rat and human kidney and urine. Comparative analysis of the immunoassay was performed on the Meso Scale Development (MSD) and Luminex platforms. Analysis on both platforms detected calbindin D28K concentrations between 100 ng/mL and 100 pg/mL. Luminex detected 10-fold the amount of calbindin D28K in samples analyzed as compared to MSD, whereas calbindin D28K level in rat and human urine was below detection limit in both platforms. The application of the immunoassays described herein may be useful in toxicological and pathological studies of distal tubular damage in rats and human.

Significant elevation of urinary 28-kD calbindin-D and N-acetyl-beta-D-glucosaminidase levels in patients undergoing extracorporeal shock wave lithotripsy.

Calbindin-D, a vitamin D-dependent calcium binding protein with a molecular mass of 28 kD, is found predominantly in distal renal tubules and central nervous system tissues in man. We have developed a highly sensitive enzyme immunoassay for human 28-kD calbindin-D and demonstrated its advantages as a new marker for damage to distal renal tubules. Urinary N-acetyl-beta-D-glucosaminidase (NAG), a lysosomal enzyme of the proximal renal tubules, is another segment-specific indicator of renal damage. To clarify whether both proximal and distal renal tubules are similarly affected by extracorporeal shock wave lithotripsy (SWL) treatment, urinary 28-kD calbindin-D and NAG were measured before, then immediately, 2 and 24 hours after SWL in 17 renal lithiasis patients. Levels of urinary calbindin-D were markedly elevated immediately and 2 hours after SWL and then decreased. In sera, levels of calbindin-D also increased, closely correlated with the changes in urinary values. Levels of urinary NAG were also significantly elevated immediately after SWL and then decreased. The results indicate that damage to both proximal and distal renal tubules occurs simultaneously with SWL and that the two markers can be applied as sensitive indicators of such side effects and their alleviation with protective agents.

Urinary 28-kD calbindin-D as a new marker for damage to distal renal tubules caused by cisplatin-based chemotherapy.

Calbindin-D, a vitamin D-dependent calcium-binding protein of 28 kD, is found predominantly in the distal tubules of the kidney and central nervous system tissues in humans. To evaluate damage to the renal tubules caused by cisplatin-based chemotherapy, levels of urinary and serum calbindin-D were determined in patients treated with cisplatin- or carboplatin-based chemotherapies using a highly sensitive enzyme immunoassay system developed in our laboratory. Levels of urinary 28-kD calbindin-D were also determined in patients with benign and malignant urological diseases. The mean urinary calbindin-D level was 2.44 + or - 0.31 (mean + or - SE) ng/mg creatinine in 40 healthy subjects. Urinary calbindin-D levels were elevated (>10 ng/mg creatinine) in 2 of 33 patients (6%) with benign and 1 of 50 (2%) with malignant urological diseases. Urinary calbindin-D levels were significantly increased after cisplatin-based chemotherapy in 14 patients, with peaks (71.8 + or - 13.5 ng/mg creatinine) being found 8 days after administration of cisplatin, and then a gradual return to the baseline. On the other hand, 7 patients receiving carboplatin-based chemotherapy demonstrated no significant elevation (highest level 7.7 + or - 2.5 ng/mg creatinine). In 7 patients treated with cisplatin-based chemotherapy the serum calbindin-D level was also raised after treatment, with a good correlation to urinary values. These findings suggest that urinary and serum calbindin-D may be kidney-derived and that 28-kDa calbindin-D is a useful marker for damage to the distal renal tubules associated with cisplatin-based chemotherapy.