Serum amyloid P component therapeutically attenuates atherosclerosis in mice via its effects on macrophages

Background: A hallmark of atherosclerosis is the formation of macrophage-derived foam cells. Serum amyloid P component (SAP), a member of the pentraxin family of proteins, is known to affect macrophage activation. However, the role of SAP in atherosclerosis is still unclear. Methods: Apolipoprotein E-deficient (Apoe(-/-)) mice fed a high-fat diet were given intraperitoneal injections of SAP (6 mg/kg) every other day for a total of 2 weeks to characterize atherosclerosis development. Results: We showed that intraperitoneal injection of SAP attenuated atherosclerosis in Apoe(-/-) mice. Immunostaining of aortic roots indicated that SAP was up-taken by the lesion area. In SAP-treated mice, serum paraoxonase1 (PON1) activity was increased whereas high-density lipoprotein inflammatory index (HII) was reduced. The cholesterol efflux rate in macrophages was elevated along with the expression of cholesterol efflux proteins. Through bioinformatics analysis followed by experimental validation, we found that proline/serine-rich coiled-coil protein 1 (Psrc1) was an important downstream effector of SAP in macrophages. Conclusions: Our findings reveal an anti-atherosclerotic role of SAP and extend the current knowledge regarding this molecule as a marker for atherosclerosis.