The role of Iex-1 in the pathogenesis of venous neointimal hyperplasia associated with hemodialysis arteriovenous fistula

PLoS One. 2014 Jul 18;9(7):e102542. doi: 10.1371/journal.pone.0102542. eCollection 2014.


Arteriovenous fistulas (AVFs) used for hemodialysis fail because of venous neointimal hyperplasia (VNH). There are 1,500,000 patients that have end stage renal disease worldwide and the majority requires hemodialysis. In the present study, the role of the intermediate early response gene X-1 (IEX-1), also known as IER-3 in the pathogenesis of VNH was evaluated. In human samples removed from failed AVF, there was a significant increase in IEX-1 expression localized to the adventitia. In Iex-1-/- mice and wild type (WT) controls, chronic kidney disease was induced and an AVF placed 28 days later by connecting the carotid artery to jugular vein. The outflow vein was removed three days following the creation of the AVF and gene expression analysis demonstrated a significant decrease in vascular endothelial growth factor-A (Vegf-A) and monocyte chemoattractant protein-1 (Mcp-1) gene expression in Iex-1-/- mice when compared to WT mice (P<0.05). At 28 days after AVF placement, histomorphometric and immune-histochemical analyses of the outflow vein demonstrated a significant decrease in neointimal hyperplasia with an increase in average lumen vessel area associated with a decrease in fibroblast, myofibroblast, and Ly6C staining. There was a decrease in proliferation (Ki-67) and an increase in the TUNEL staining in Iex-1 KO mice compared to WT. In addition, there was a decrease in Vegf-A, Mcp-1, and matrix metalloproteiniase-9 (Mmp-9) staining. Iex-1 expression was reduced in vivo and in vitro using nanoparticles coated with calcitriol, an inhibitor of Iex-1 that demonstrated that Iex-1 reduction results in decrease in Vegf-A. In aggregate, these results indicate that the absence of IEX-1 gene results in reduced VNH accompanied with a decrease in proliferation, reduced fibroblast, myofibroblast, and Ly6C staining accompanied with increased apoptosis mediated through a reduction in Vegf-A/Mcp-1 axis and Mmp-9. Adventitial delivery of nanoparticles coated with calcitriol reduced Iex-1 and VNH.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Apoptosis Regulatory Proteins / analysis
  • Apoptosis Regulatory Proteins / physiology*
  • Arteriovenous Shunt, Surgical / adverse effects*
  • Calcitriol / administration & dosage
  • Calcitriol / pharmacology
  • Calcitriol / therapeutic use
  • Chemokine CCL2 / biosynthesis
  • Chemokine CCL2 / genetics
  • Fibroblasts / pathology
  • Humans
  • Hydrogels
  • Hyperplasia
  • Immediate-Early Proteins / deficiency*
  • Immediate-Early Proteins / physiology
  • Kidney Failure, Chronic / therapy
  • Lactic Acid
  • Male
  • Matrix Metalloproteinase 9 / biosynthesis
  • Matrix Metalloproteinase 9 / genetics
  • Membrane Proteins / analysis
  • Membrane Proteins / physiology*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Myofibroblasts / pathology
  • Nanoparticles
  • Polyglycolic Acid
  • Polylactic Acid-Polyglycolic Acid Copolymer
  • Renal Dialysis*
  • Tunica Intima / metabolism
  • Tunica Intima / pathology*
  • Vascular Endothelial Growth Factor A / biosynthesis
  • Vascular Endothelial Growth Factor A / genetics
  • Veins / pathology*


  • Apoptosis Regulatory Proteins
  • Ccl2 protein, mouse
  • Chemokine CCL2
  • Hydrogels
  • IER3 protein, human
  • IEX-1 protein, mouse
  • Immediate-Early Proteins
  • Membrane Proteins
  • Vascular Endothelial Growth Factor A
  • vascular endothelial growth factor A, mouse
  • Polylactic Acid-Polyglycolic Acid Copolymer
  • Polyglycolic Acid
  • Lactic Acid
  • Matrix Metalloproteinase 9
  • Calcitriol