Chaperonin-Containing t-Complex Protein-1 Subunit β as a Possible Biomarker for the Phase of Glomerular Hyperfiltration of Diabetic Nephropathy

In cell model, we discovered the association between chaperonin-containing t-complex polypeptide 1 subunit β (TCP-1β) and early diabetic nephropathy (DN). In this study, we further explored the relationships between TCP-1β and type 2 diabetic mellitus (DM). To mimic the clinical hyperfiltration state, a type 2 DM mice model was established by feeding a high-fat diet in combination with treatment of streptozotocin and nicotinamide. Blood and urine were collected to determine creatinine clearance (C cr), and kidney tissues were harvested for evaluation of TCP-1β expression by immunohistochemistry and Western blot. Meanwhile, clinical subjects of healthy controls and type 2 DM were recruited to strengthen the evidence with urine TCP-1β. Results showed that C cr and the expression of TCP-1β in kidney were significantly higher one week after hyperglycemia development, suggesting that the hyperfiltration state was successfully established in the mice model. TCP-1β was expressed predominantly on renal tubules. By using the estimated glomerular filtration rate to index progression in clinical investigation, urine TCP-1β level was associated with the hyperfiltration phase in type 2 DM patients. Conclusively, we confirmed that TCP-1β is a possible biomarker for early nephropathy of type 2 DM, but further mechanistic study to elucidate its cause and pathway is needed.