We have previously reported that nuclear factor of activated T cells (NFATs) play an important role in the regulation of vascular smooth muscle cell migration and proliferation by receptor tyrosine kinase and G proteincoupled receptor agonists, platelet-derived growth factor-BB and thrombin, respectively. To understand the role of NFATs in vascular disease, we have now studied the involvement of these transcription factors in neointima formation in a rat carotid artery balloon injury model. The levels of NFATc1 in injured right common carotid arteries were increased at 72 h, 1 week, and 2 weeks after balloon injury compared with its levels in uninjured left common carotid arteries. Intraperitoneal injection of cyclosporine A (CsA), a pharmacological inhibitor of the calcineurin-NFAT activation pathway, suppressed balloon injury-induced neointima formation by 40%. Similarly, adenoviral-mediated expression of GFPVIVIT, a competent peptide inhibitor of the calcineurin-NFAT activation pathway, in injured arteries also reduced neointima formation by about 40%. Furthermore, CsA and GFPVIVIT attenuated balloon injury-induced neointimal smooth muscle cell proliferation as determined by bromodeoxyuridine staining. Platelet-derived growth factor-BB induced the expression of COX-2 in cultured VSMC in a time-and NFAT-dependent manner. COX-2 expression was also increased in the right common carotid artery in a time-dependent manner after balloon injury as compared with its levels in uninjured left common carotid artery and both CsA and GFPVIVIT negated this response. Together these results for the first time demonstrate that NFATs play a critical role in neointima formation via induction of expression of COX-2.

Expression of atheroprotective genes in the blood vessel wall is potentially an effective means of preventing or reversing atherosclerosis. Development of this approach has been hampered by lack of a suitable gene-transfer vector. We used a helper-dependent adenoviral (HDAd) vector to test whether expression of apolipoprotein A-I (apoA-I) in the artery wall could retard the development of atherosclerosis in hyperlipidemic rabbits. Carotid arteries were infused with an HDAd expressing rabbit apoA-I or a "null" HDAd and harvested 2 and 4 weeks later. ApoA-I mRNA and protein were detected only in HDAdApoAI arteries. Lesion size, lipid and macrophage content, and adhesion molecule expression were similar in both groups at 2 weeks. Between 2 and 4 weeks, most of these measures of atherosclerosis increased in HDAdNull arteries, but were stable or decreased in HDAdApoAI arteries (P ≤ 0.04 for all end points in 4-week HDAdApoAI versus HDAdNull arteries). A longer-term study in chow-fed rabbits revealed persistence of HDAd vector DNA and apoA-I expression for ≥48 weeks, with stable vector DNA content and apoA-I expression from 4 to 48 weeks. Expression of apoA-I in arterial endothelium significantly retards atherosclerosis. HDAd provides prolonged, stable expression of a therapeutic transgene in the artery wall.

In addition to their role in cytokine gene regulation in T cells, nuclear factors of activated T cells (NFATs) have been shown to be involved in cardiac development and hypertrophy. We have reported previously that NFATs play an important role in the regulation of vascular smooth muscle cell (VSMC) proliferation by receptor tyrosine kinase (RTK) and G protein-coupled receptor (GPCR) agonists, platelet-derived growth factor-BB (PDGF-BB) and thrombin, respectively. To understand the role of NFATs in vascular disease and development, we have now studied the role of these transcriptional factors in VSMC motility. PDGF-BB and thrombin induced VSMC motility in a dose-dependent manner.

The success of gene therapy hinges on achievement of adequate transgene expression. To ensure high transgene expression, many gene-therapy vectors include highly active virus-derived transcriptional elements. Other vectors include tissue-specific eukaryotic transcriptional elements, intended to limit transgene expression to specific cell types, avoid toxicity, and prevent immune responses. Unfortunately, tissue specificity is often accompanied by lower transgene expression. Here we use eukaryotic (murine) transcriptional elements and a virus-derived posttranscriptional element to build cassettes designed to express a potentially therapeutic gene (interleukin-10) in large vessel endothelial cells (EC) at levels as high as obtained with the CMV immediate-early promoter, while retaining EC-specificity. The cassettes were tested by incorporation into helper-dependent adenoviral vectors, and transduction into bovine aortic EC in vitro and rabbit carotid EC in vivo. The murine endothelin-1 promoter showed EC-specificity, but expressed only 3% as much IL-10 mRNA as CMV. Inclusion of precisely 4 copies of an EC-specific enhancer and a posttranscriptional regulatory element increased IL-10 expression to a level at or above the CMV promoter in vivo, while retaining—and possibly enhancing—EC specificity, as measured in vitro. The cassette reported here will likely be useful for maximizing transgene expression in large vessel EC, while minimizing systemic effects.