C-Reactive Protein Downregulates Endothelial NO Synthase and Attenuates Reendothelialization In Vivo in Mice

Abstract

C-reactive protein (CRP) is an acute-phase reactant that is positively associated with cardiovascular disease risk and endothelial dysfunction. In cell culture, CRP decreases the expression of endothelial NO synthase (eNOS), which regulates diverse endothelial cell (EC) functions including migration. To determine whether CRP alters EC gene expression and phenotype in vivo, we studied CF1 transgenic mice expressing rabbit CRP (CF1-CRP) regulated by the phosphoenolpyruvate carboxykinase promoter such that levels could be altered by changing carbohydrate intake. Compared with CF1 controls with CRP of <1 microg/mL, carotid artery reendothelialization after perivascular electric injury was blunted in CF1-CRP mice, with CRP levels as low as 9 microg/mL. eNOS mRNA and enzyme abundance in carotid arteries was also blunted by CRP at 9 microg/mL in vivo, and ex vivo studies of isolated arteries showed that this occurs via direct action on the endothelium. The impaired reendothelialization with CRP was mimicked by NOS antagonism in CF1 mice; conversely, in cultured ECs CRP attenuation of migration was prevented by exogenous NO. Studies of EC transfected with human eNOS 5' flanking sequence fused to luciferase indicated that CRP decreases eNOS gene transcription. Both mutagenesis and electrophoretic mobility shift assays further revealed that CRP-responsive elements reside within the first 79 bp of the eNOS promoter. Thus, CRP downregulates eNOS and attenuates reendothelialization in vivo in mice, and this action of CRP on eNOS is mediated at the level of gene transcription.