YBX1/PPIB axis promotes post-maturation arteriovenous fistula stenosis via enhancing endothelial to mesenchymal transition.

Arteriovenous fistulas (AVFs) exhibit a high incidence of stenosis after maturation, which is a major cause of access failure in hemodialysis patients. However, its cellular heterogeneity and molecular mechanisms are not well clarified. For patients with post-maturation AVF stenosis (AVFS), we applied single-cell RNA sequencing on AVFS and matched non-stenotic vessels, followed by differential expression and pathway analyses to identify candidate cell types, genes and potential functional changes. Upstream transcription factors of the candidate genes were predicted using AnimalTFDB. The predicted molecular pathway was validated in vitro using HUVECs. Dual-luciferase assays tested transcription factor-gene interactions; qRT-PCR and Western blotting measured expression levels; immunofluorescence staining detected α-SMA; and wound healing assays assessed cell migration. Eight vascular cell types were identified, with endothelial cells showing the greatest proportional increase in AVFS. Differential expression analysis highlighted PPIB as the candidate gene, and enrichment analyses implicated endothelial-to-mesenchymal transition (EndMT). PPIB could promotes EndMT, as indicated by decreased VE-cadherin/CD31, increased α-SMA, and enhanced migration. Upstream transcription factor prediction identified YBX1 as a direct transcriptional regulator of PPIB, and dual-luciferase assays confirmed their interaction. YBX1 overexpression elevated PPIB levels and accelerated EndMT, whereas PPIB knockdown reversed these effects. This study reveals a novel YBX1–PPIB regulatory axis driving EndMT in endothelial cells, thereby contributing to post-maturation AVFS pathogenesis. These findings provide mechanistic insights and suggest potential therapeutic targets for preventing post-maturation AVFS.