INTRODUCTION:
Vascular remodeling orchestrates a complex network of signaling pathways responsible for pathological changes in many vascular diseases such as atherosclerosis. We investigated the role of endoplasmic reticulum chaperone Protein Disulfide Isomerase (PDI) and the extracellular PDI (ecPDI) pool in vascular caliber and architecture during vascular repair and remodeling after injury (AI).
METHODS AND RESULTS:
After rabbit iliac artery balloon injury, PDI is markedly increased at mRNA and protein levels (25-fold vs. basal 14 days AI), with increase in both intracellular and ecPDI. Silencing PDI by siRNA in vitro induced ER stress markers upregulation and apoptosis (assessed by TUNEL assay). PDI knockdown also upregulated proliferation marker PCNA and decreased differentiation marker calponin-C. Furthermore, ecPDI inhibition prevents injury-increased hydrogen peroxide generation and decreases arterial nitrate (NO3-) level. EcPDI neutralization in vivo with PDIAb-containing perivascular gel from days 12-14AI promoted 25% decrease in vascular caliber at arteriography and similar decreases in total vessel circumference at optical coherence tomography, without changing neointima, indicating increased constrictive remodeling. EcPDI neutralization promoted striking changes in collagen, with switch from circumferential to radial fiber orientation towards a more rigid fiber type. Collagen type I and III were decreased after ecPDI inhibition in arteries 14 days AI. Cytoskeleton architecture was also disrupted, with loss of stress fiber coherent organization and switch from thin to medium-thickness actin fibers. In human coronary atheromas, PDI expression inversely correlated with constrictive remodeling. There was decreased PDI expression in media and intima from plaques exhibiting constrictive remodeling and, conversely, enhanced PDI expression in media of plaques depicting outward remodeling.
CONCLUSIONS:
Thus, PDI is highly upregulated after injury and reshapes matrix and cytoskeleton architecture to support an anticonstrictive remodeling effect. Such findings suggest an important role for PDI in lumen maintenance during vascular remodeling.
Defective folding and stable association with protein disulfide isomerase/prolyl hydroxylase of type I procollagen with a deletion in the pro alpha 2(I) chain that preserves the Gly-X-Y repeat pattern.
