Adventitial delivery of dominant-negative p67phox attenuates neointimal hyperplasia of the rat carotid artery

Several essential components of NADPH oxidase, including p22(phox), gp91(phox) (nox2) and its homologs nox1 and nox4, p47(phox), p67(phox), and rac1, are present in the vasculature. We previously reported that p67(phox) is essential for adventitial fibroblast NADPH oxidase O-2(-) production. Thus we postulated that inhibition of adventitial p67(phox) activity would attenuate angioplasty-induced hyperplasia. To test this hypothesis, we treated the adventitia of carotid arteries with a control adenovirus (Ad-control), a virus expressing dominant-negative p67(phox) (Ad-p67dn), or a virus expressing a competitive peptide (gp91ds) targeting the p47(phox)- gp91(phox) interaction (Ad-gp91ds). Common carotid arteries (CCAs) from male Sprague-Dawley rats were transfected with Ad-control, Ad-p67dn, or Ad-gp91ds in pluronic gel. After 2 days, a 2-F ( Fogarty) catheter was used to injure CCAs in vivo. After 14 days, CCAs were perfusion-fixed and analyzed. In 13 experiments, digital morphometry suggested a reduction of neointimal hyperplasia with Ad-p67dn compared with Ad-control; however, the reduction did not reach statistical significance ( P = 0.058). In contrast, a significant reduction was achieved with Adgp91ds ( P = 0.006). No changes in medial area or remodeling were observed with either treatment. Moreover, adventitial fibroblast proliferation in vitro was inhibited by Ad-gp91ds but not by Ad-p67dn, despite confirmation that Ad-p67dn inhibits NADPH oxidase in fibroblasts. These data appear to suggest that a multicomponent vascular NADPH oxidase plays a role in neointimal hyperplasia. However, inhibition of p47(phox) may be more effective than inhibition of p67(phox) at attenuating neointimal growth.