C-reactive protein and asymmetric dimethylarginine: markers or mediators in cardiovascular disorders?

C-reactive protein (CRP) has received much attention as a cardiovascular risk factor and has been recommended to be used in screening to assist in predicting the occurrence of cardiovascular disorders. There are numerous association studies documenting changes in circulating CRP concentrations, there are, however, fewer studies providing evidence that CRP mediates the progression of cardiovascular pathologies. Elucidating the potential mechanisms for CRP has been confounded by recent reports that contaminants of CRP are partially responsible for observed effects. In this review the use of CRP as a tool to predict cardiovascular disorders will be discussed alongside a more recently described cardiovascular risk factor asymmetric dimethylarginine (ADMA). An endogenously occurring nitric oxide synthase inhibitor, ADMA, is formed by the action of protein arginine methyltransferases and subsequent proteolysis and it is metabolised in vivo by the dimethylarginine dimethylaminohydrolases (DDAH). The evidence available documenting the effects of CRP and ADMA, the regulatory mechanisms and the genetic influences, will be discussed in order to determine whether CRP and ADMA are mediators in the progression of cardiovascular disorders or merely useful biomarkers.