Advertisement

Transforming Growth Factor-beta Signaling Mediates Endothelial-to-mesenchymal Transition during Arteriovenous Fistula Remodeling in the Chronic Kidney Disease Environment

Open AccessPublished:June 10, 2022DOI:https://doi.org/10.1016/j.jvssci.2022.05.009

      Objectives

      Arteriovenous fistulae (AVF) are the optimal conduit for hemodialysis access in patients with end-stage chronic kidney disease (CKD); however, AVF have high rates of failure due to aggressive neointimal hyperplasia. Neointimal hyperplasia in the CKD environment is characterized by endothelial-to-mesenchymal transition. We hypothesized that endothelial transforming growth factor (TGF)-β signaling promotes endothelial-to-mesenchymal transition to cause AVF failure.

      Methods

      Aortocaval AVF were created in C57BL/6J mice, with control mice having sham procedures. Three weeks before AVF, CKD was created via 5/6 nephrectomy (Nx); five groups were tested, including sham, sham+5/6Nx, AVF+0/6Nx, AVF+3/6Nx, and AVF+5/6Nx. Endothelial cell (EC)-and smooth muscle cell (SMC)-specific TGFβRI II knockout (KO) mice were treated with tamoxifen 2 weeks before AVF; ultrasound examination was used to determine AVF diameter and patency at postoperative days 7, 14, and 21. AVF were harvested at days 7 or 21 and examined with histology, Immunofluorescence and Western blot.

      Results

      There was no difference between mice treated with 0/6Nx or 3/6Nx regarding AVF diameter, AVF wall thickness, or accumulation of extracellular matrix components fibronectin, collagen 1, and collagen 3; however, AVF diameter was significantly decreased in mice treated with 5/6Nx compared with 0/6Nx or 3/6Nx, whereas there was increased AVF wall thickness as well as immunoreactivity of fibronectin (P = .031), collagen 1 (P = .022), collagen 3 (P = .005), and TGF-β1 (P = .022), compared with 0/6Nx. ECs in the AVF of mice treated with 5/6Nx had significantly increased immunoreactivity of the mesenchymal markers notch3 (P < .0001), vimentin (P < .0001), and FSP-1 (P = .02) compared with 0/6Nx. However, blocking TGFβ signaling using either EC-KO or SMC-KO mice had significantly decreased immunoreactivity of mesenchymal markers and wall thickness (P < .0001), consistent with reduced endothelial-to-mesenchymal transition and an increased diameter (P = .035). Interestingly, the AVF wall thickness in EC-KO mice was thinner than in SMC-KO mice.

      Conclusions

      Both EC- and SMC-specific TGF-β signaling promote endothelial-to-mesenchymal transition and wall thickening during venous remodeling in the CKD environment. These data suggest that the TGF-β signaling pathway may be a potential therapeutic target to prevent AVF failure.