Plasma vitamin K-dependent protein C as early diagnostic marker of feline chronic kidney disease

抄録

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 control cats. We recently described a simple and highly reproducible tandem mass tag (TMT) labelling method for identifying potential disease-marker candidates among low-abundance plasma proteins. In the current study, plasma samples were obtained from 90 normal control cats and 50 cats with CKD (stage 1). To identify new plasma biomarkers for CKD, six plasma samples (three from normal control cats and three from CKD stage 1 cats) were extracted with SSA lectin magnetic beads, differentially labelled with TMTs, digested with trypsin and subjected to analysis using LC-MS/MS. Sialylated Vitamin K-dependent protein C was identified as a protein with lower levels in CKD stage 1 cats compared to normal control cats. An ELISA of plasma sialylated vitamin K-dependent protein C showed within-run (4.3–4.9%) and between-day (4.3–5.2%) reproducibility. Plasma sialylated vitamin K-dependent protein C levels measured with this assay were significantly greater in normal control cats than in CKD stage 1 cats (1.40±0.13 vs. 1.07±0.11 AU/mL, p<0.001). These results indicate that sialylated vitamin K-dependent protein C may be useful as a complementary marker with plasma creatinine, BUN and SDMA for detection of CKD stage 1 in cats.