V ascular remodeling involves changes for the whole-vessel circumference and crucially determines lumen caliber 1 in physio(patho)logical situations, such as shear-stress responses, restenosis postangioplasty, 1-3 or native atherosclerosis. 1,4 Moreover, cellular mechanisms governing conductance vessel remodeling are likely shared by small-vessel remodeling, for example, in hypertension.5 Despite such relevance, mechanisms of vessel remodeling are not well known. The identification of endothelium 6 and nitric oxide 7 dependency of shear-induced remodeling raised possible mediator roles of redox processes, as indeed supported by many subsequent studies. 3,8 We showed previously that superoxide dismutase underactivity favors constrictive remodeling after injury (AI), whereas exogenous replenishment of SOD3(ecSOD) rescued bioactive nitric oxide from inducible NO synthase and normalized vessel caliber by counteracting constrictive remodeling rather than neointimal growth. 3 The randomized clinical trial Multivitamins and Probucol Study showed that the antioxidant probucol significantly prevented restenosis postballoon angioplasty, essentially by preventing constrictive remodeling rather than neointima formation.
9Such redox-responsiveness is in line with the importance of redox pathways in cytoskeletal dynamics 10 and extracellular matrix organization, 11 which are both crucially involved in vessel remodeling. However, molecular determinants of such redox signaling pathways remain unclear.Abstract-Whole-vessel remodeling critically determines lumen caliber in vascular (patho)physiology, and it is reportedly redox-dependent. We hypothesized that the cell-surface pool of the endoplasmic reticulum redox chaperone protein disulfide isomerase-A1 (peri/epicellular=pecPDI), which is known to support thrombosis, also regulates disease-associated vascular architecture. In human coronary atheromas, PDI expression inversely correlated with constrictive remodeling and plaque stability. In a rabbit iliac artery overdistension model, there was unusually high PDI upregulation (≈25-fold versus basal, 14 days postinjury), involving both intracellular and pecPDI. PecPDI neutralization with distinct anti-PDI antibodies did not enhance endoplasmic reticulum stress or apoptosis. In vivo pecPDI neutralization with PDI antibodycontaining perivascular gel from days 12 to 14 post injury promoted 25% decrease in the maximally dilated arteriographic vascular caliber. There was corresponding whole-vessel circumference loss using optical coherence tomography without change in neointima, which indicates constrictive remodeling. This was accompanied by decreased hydrogen peroxide generation. Constrictive remodeling was corroborated by marked changes in collagen organization, that is, switching from circumferential to radial fiber orientation and to a more rigid fiber type. The cytoskeleton architecture was also disrupted; there was a loss of stress fiber coherent organization and a switch from thin to medium thickness actin fibers, all leading to...