A brief elevation of serum amyloid A is suffi cient to increase atherosclerosis

Serum amyloid A (SAA) has a number of proatherogenic effects including induction of vascular proteoglycans. Chronically elevated SAA was recently shown to increase atherosclerosis in mice. The purpose of this study was to determine whether a brief increase in SAA similarly increased atherosclerosis in a murine model. The recombination activating gene 1-defi cient ( rag1 ) × apolipoprotein E-defi cient ( apoe ) and apoe male mice were injected, multiple times or just once respectively, with an adenoviral vector encoding human SAA1 (ad-SAA); the injected mice and controls were maintained on chow for 12-16 weeks. Mice receiving multiple injections of ad-SAA, in which SAA elevation was sustained, had increased atherosclerosis compared with controls. Strikingly, mice receiving only a single injection of ad-SAA, in which SAA was only briefl y elevated, also had increased atherosclerosis compared with controls. Using in vitro studies, we demonstrate that SAA treatment leads to increased LDL retention, and that prevention of transforming growth factor beta (TGF-) signaling prevents SAA-induced increases in LDL retention and SAAinduced increases in vascular biglycan content. We propose that SAA increases atherosclerosis development via induction of TGF-, increased vascular biglycan content, and increased LDL retention. These data suggest that even short-term infl ammation with concomitant increase in SAA may increase the risk of developing CVD.