The Reduction of Uromodulin, Complement Factor H, and Their Interaction Is Associated with Acute Kidney Injury to Chronic Kidney Disease Transition in a Four-Time Cisplatin-Injected Rat Model

Abstract

Uromodulin is recognized as a protective factor during AKI-to-CKD progression, but the mechanism remains unclear. We previously reported that uromodulin interacts with complement factor H (CFH) in vitro, and currently aimed to study the expression and interaction evolution of uromodulin and CFH during AKI-to-CKD transition. We successfully established a rat model of AKI-to-CKD transition induced by a four-time cisplatin treatment. The blood levels of BUN, SCR, KIM-1 and NGAL increased significantly during the acute injury phase and exhibited an uptrend in chronic progression. PAS staining showed the nephrotoxic effects of four-time cisplatin injection on renal tubules, and Sirius red highlighted the increasing collagen fiber. Protein and mRNA levels of uromodulin decreased while urine levels increased in acute renal injury on chronic background. An extremely diminished level of uromodulin correlated with severe renal fibrosis. RNA sequencing revealed an upregulation of the alternative pathway in the acute stage. Renal CFH gene expression showed an upward tendency, while blood CFH localized less, decreasing the abundance of CFH in kidney and following sustained C3 deposition. A co-IP assay detected the linkage between uromodulin and CFH. In the model of AKI-to-CKD transition, the levels of uromodulin and CFH decreased, which correlated with kidney dysfunction and fibrosis. The interaction between uromodulin and CFH might participate in AKI-to-CKD transition.