Knock-down of Nuclear Factor-kappa B expression by RNA interference inhibits Intimal Hyperplasia After Balloon Denudation Rat Arterial Injury

Purpose: Vascular injury and inflammation are associated with a number of cytokines which transduce signals through muItiple pathways to act as smooth muscle cell (SMC) mitogens. Activation of the nuclear factor-kappa B (NF-kB) transcription factor is essential for SMC proliferation and occurs in response to vascular injury in vivo. The purpose of this study was to determine whether knock-down of NF-kB expression mediated by RNAi using a lentiviral vector could inhibit the development of intimal hyperplasia and SMC proliferation. Methods: A rat iliac injury model was used to study the prevention of intimal hyperplasia (IH). Arteries were assayed at the 3rd & 7th day after injury and infection with shLentil.1/NF-B？？. This probe contains an NF-kB interfering target sequence, AACGATGTTGAGTACCAGTGT. SMCs infected with RNAi NF-kB were measured by immunostaining. The protein level of NF-kB was determined by Western blotting. Proliferation was measured by I/MR (intima to media ratio). Results: Infection with RNAi NF-kB significantly suppressed in vivo proliferation of SMCs & intimal thickening. Inhibition of proliferation was associated with decreased NF-kB levels. Conclusions: Suppression of NF-kB inhibited the development of intimal hyperplasia and SMC proliferation in vivo. Further vascular biology studies and delineation of the molecular mechanisms underlying intimal hyperplasia will help to identify additional targets for gene therapy as well as improving our current concepts. Also, as demonstrated here, RNAi could be a useful tool for inhibiting IH.