Immunohistochemical analysis of paraoxonases-1 and 3 in human atheromatous plaques.

Background The paraoxonase (PON) enzyme family comprising PON1, PON2 and PON3 are antioxidant enzymes that degrade bioactive oxidised lipids and are thus antiatherogenic. Materials and methods We investigated the localisation of the PON proteins during the development of atherosclerosis by immunohistochemical analysis. Results In normal aortas, PON1 and PON3 were localised to smooth muscle cells (SMC) and endothelial cells. PON3 staining was stronger than that of PON1. During atherosclerosis development, SMC staining for PON1 and PON3 was greatly reduced, while macrophage staining for both proteins increased with PON1 predominating. Macrophage staining for PON1 and PON3 was significantly and positively related to the amount of aortic inflammation (both P < 0·001). Conclusions Our data add support to the growing body of evidence for a cellular protective effect of PON1 and PON3 against the proinflammatory / proatherosclerotic effects of lipid peroxidation. [ABSTRACT FROM AUTHOR]