2022 Volume 6 Issue 1 Pages 36-44
Chronic kidney disease (CKD) is a common disorder and cause of death in cats. In the classification proposed by the International Renal Interest Society (IRIS), stage 1 and 2 CKD are difficult to diagnose accurately using markers, in comparison with normal controls. We recently described a simple and highly reproducible tandem mass tag labelling method for identifying potential disease-marker candidates among low-abundance urine proteins. In the current study, urine samples were obtained from 90 normal control cats as the control group and from 50 cats with CKD (stage 1). To identify new urine biomarkers for CKD, two pool urine samples (normal controls and CKD stage 1 cats) were differentially labelled with TMT, subjected to analysis using SDS-PAGE, digested with trypsin and subjected to analysis using LC-MS/MS. Kidney injury molecule-1 (KIM-1) was identified as a protein with higher levels in cats with CKD (stage 1). An ELISA of urine KIM-1 showed within-run (3.2–4.5%) and between-day (3.4–4.8%) reproducibility. Urine KIM-1 levels measured with this assay were significantly greater in CKD (stage 1) cats than in normal cats (63.7±10.7 vs. 35.7±9.7 μg/g Cre, p<0.001). These results indicate that KIM-1 may be useful as a complementary marker with p-Cre and BUN for detection of CKD (stage 1) in cats.
