C-reactive protein causes downregulation of vascular angiotensin subtype 2 receptors and systolic hypertension in mice

Background - Chronic elevations in circulating C-reactive protein (CRP) are associated with a greater risk of hypertension. Whether elevations in CRP cause hypertension is unknown. Methods and Results - Chronic, conscious blood pressure ( BP) measurements were performed by radiotelemetry in wild-type CF1 control and CF1 transgenic mice expressing rabbit CRP (CF1-CRP) under the regulation of the phosphoenolpyruvate carboxykinase promoter. Compared with controls, CF1-CRP mice had hypertension that was predominantly systolic, and the severity of hypertension varied in parallel with changes in CRP levels modulated by dietary manipulation. Mice that were hemizygous for the transgene with CRP levels of 9 mu g/mL were also hypertensive, indicating that modest elevations in CRP are sufficient to alter BP. CRP transgenic mice had exaggerated BP elevation in response to angiotensin II and a reduction in vascular angiotensin receptor subtype 2 (AT(2)) expression. In contrast, the decline in BP with angiotensin receptor subtype 1 (AT(1)) antagonism and vascular AT(1) abundance were unaltered, which indicates a selective effect of CRP on AT(2). Ex vivo experiments further showed that the CRP-induced decrease in AT(2) is a direct effect on the vascular wall, not requiring systemic responses, and that it is reversed by an NO donor, which indicates a role for NO deficiency in the process. In parallel, the chronic inhibition of NO synthase in wild-type mice attenuated vascular AT(2) expression without affecting AT(1). Conclusions - These findings provide direct evidence for CRP-induced hypertension, and they further identify a novel underlying mechanism involving downregulation of AT(2) related to NO deficiency.