Cyclic adenosine monophosphate response-element binding protein activation by mitogen-activated protein kinase-activated protein kinase 3 and four-and-a-half LIM domains 5 plays a key role for vein graft intimal hyperplasia

Objective: Intimal hyperplasia (IH) is the main cause of vein graft stenosis or failure after bypass surgery. Basic investigations are proceeding in an animal model of mechanically desquamated arteries, and numerous molecules for potential IH treatments have been identified; however, neither insights into the mechanism of IH nor substantially effective treatments for its suppression have been developed. The goals of the present study are to use human vein graft samples to identify therapeutic target genes that control IH and to investigate the therapeutic efficacy of these candidate molecules in animal models. Methods: Using microarray analysis of human vein graft samples, we identified two previously unrecognized IH-related genes, mitogen-activated protein kinase-activated protein kinase 3 (MAPKAPK3) and four-and-a-half LIM domains 5 (FHL5). Results: Transfer of either candidate gene resulted in significantly elevated vascular smooth muscle cell (VSMC) proliferation and migration. Interestingly, cotransfection of both genes increased VSMC proliferation in an additive manner. These genes activated cyclic adenosine monophosphate response-element (CRE) binding protein (CREB), but their mechanisms of activation were different. MAPKAPK3 phosphorylated CREB, but FHL5 bound directly to CREB. A CREB dominant-negative protein, KCREB, which blocks its ability to bind CRE, repressed VSMC proliferation and migration. In a wire-injury mouse model, gene transfer of KCREB plasmid significantly repressed IH. In this vessel tissue, CRE-activated gene expression was repressed. Furthermore, we confirmed the changes in MAPKAPK3 and FHL5 expression using vein graft samples from eight patients. Conclusions: We successively identified two previously unrecognized IH activators, MAPKAPK3 and FHL5, using human vein graft samples. Gene transfer of KCREB repressed IH in an animal model. Inhibition of CREB function is a promising gene therapy strategy for IH. (J Vasc Surg 2013;57:182-93.) Clinical Relevance: Intimal hyperplasia (IH) is the cause of vein graft stenosis or failure after bypass surgery. However, no therapeutic targets for the treatment of IH have been identified. We identified two previously unrecognized IH-inducing molecules, mitogen-activated protein kinase-activated protein kinase 3 (MAPKAPK3) and four-and-a-half LIM domains 5 (FHL5), using gene expression profiling of human vein graft samples and demonstrated that MAPKAPK3 and FHL5 can activate cyclic adenosine monophosphate response-element binding protein (CREB) and a promising strategy for treating IH via gene transfer of KREB, a dominant-negative variant. Our study began with one patient, and we confirmed our findings on MAPKAPK3 and FHL5 expression using vein samples from eight other patients. We believe that these results will lead to new clinical approaches to IH.