Overexpression of mutated IκBα inhibits vascular smooth muscle cell proliferation and intimal hyperplasia formation

Abstract Purpose Vascular injury and inflammation are associated with elaboration of a number of cytokines that signal through multiple pathways to act as smooth muscle cell (SMC) mitogens. Activation of the nuclear factor–kappa B (NF-κB) transcription factor is essential for SMC proliferation in vitro and is activated by vascular injury in vivo. Activation of NF-κB is controlled by several upstream regulators, including the inhibitors of kappa B (IκB). These proteins bind to and keep NF-κB inactivated. The purpose of this study was to determine whether adenoviral gene transfer of a mutated IκBα super-repressor (AdIκBα SR ) could inhibit development of intimal hyperplasia in vivo and to investigate how over-expression of this construct influences in vitro SMC proliferation and cell cycle regulatory proteins. Methods A rat carotid injury model was used to study prevention of intimal hyperplasia. Arteries were assayed 14 days after injury and infection with AdIκBαSR or adenoviral β-galactosidase (AdLacZ). Untreated SMC or SMC infected with AdLacZ or AdIκBαSR were stimulated with 10% fetal bovine serum, interleukin-1β, or tumor necrosis factor-α. Electrophoretic mobility shift assays were used to assay for NF-κB activation. Protein levels of IκBα and cyclin-dependent kinase inhibitors p21 Cip1/Waf1 and p27 Kip1 were determined with Western blot analysis. Proliferation was measured with 3 H-thymidine incorporation assays. Results AdIκBαSR inhibited the development of intimal hyperplasia by 49% ( P Cip1/Waf1 and p27 Kip1 protein levels. Conclusions Gene transfer of IκBα super-repressor inhibited development of intimal hyperplasia in vivo and SMC proliferation in vitro. The antiproliferative activity may be related to cell cycle arrest through upregulation of the cyclin-dependent kinase inhibitors p21 and p27. Overexpression of IκBα may be a future therapeutic option in treatment of vascular diseases.