C-reactive protein is an atheroprotective molecule

The co-localization of plasma C-reactive protein (CRP) and atherogenic low-density lipoprotein (LDL) at the atherosclerotic lesions raises the possibility of a role of CRP in the disease process. In vitro, in its native pentameric structural form, CRP does not bind to oxidized LDL. However, in its non-native pentameric structural form, CRP is capable of binding to oxidized LDL. It has been proposed that CRP changes its structure at sites of inflammation to gain the oxidized LDL-binding activity. In vivo, native CRP is neither pro-atherosclerotic nor atheroprotective in animal models of atherosclerosis. We assumed that native CRP shows no effect because inflammatory microenvironment in the arterial wall in animal models of atherosclerosis is not appropriate and, therefore, the structure of CRP remains unchanged. Accordingly, we hypothesized that a CRP mutant, generated by site-directed mutagenesis, capable of binding to oxidized LDL without the requirement of any further structural change should show an effect on the disease. In the current study, we evaluated the impact of such a CRP mutant on the development of atherosclerosis employing LDL receptor knockout mouse model of atherosclerosis. We found that there was a two-week delay in the development of atherosclerotic lesions in the aortic root of mice treated with mutant CRP compared to mice that did not receive CRP. The development of atherosclerotic lesions in the whole aorta was also reduced; there was 30% reduction in the size of lesions in mice treated with mutant CRP. Overall, the data indicate that CRP is indeed an atheroprotective molecule