Abstract 361: Oxidized Phospholipids Are Proinflammatory and Proatherogenic

Oxidized phospholipids (OxPL) are ubiquitously generated during inflammation, and found on apoptotic cells, OxLDL, and Lp(a). They facilitate uptake of OxLDL by macrophages (Mac) and mediate cellular inflammatory responses. The E06 natural IgM binds to the PC of OxPL, neutralizing biological effects and inhibiting OxLDL uptake by Mac. To determine the role of OxPL in atherogenesis, we generated transgenic mice expressing a single chain variant (scFv) of E06 in Ldlr background (E06-Tg). E06-scFv was secreted into plasma, bound to OxLDL and had sufficient titer to inhibit OxLDL uptake into Mac. E06-Tg or Ldlr mice were fed 1% Chol diet for 4, 7 or 12 months (n=12-15 mice/group). Plasma Chol was ~ 1600 mg/dL in all mice. Atherosclerosis decreased in E06-Tg mice: En face lesions decreased 57%, 34% and 28%, and aortic root lesions decreased 55%, 41% and 26% at 4, 7 and 12-months, respectively. OxLDL uptake by Macs was decreased: Thus, in E06-Tg mice, the uptake by peritoneal Mac of fluorescently-labeled OxLDL injected ip was decreased ~ 50%, as was peritoneal Mac Chol content. As Macs secrete E06-scFv, we performed BMT from E06-Tg donors into irradiated Ldlr recipients (n=10-12): This also decreased lesions 31% compared to BMT from control donors, even though plasma titers of E06-scFv were ~10% of Tg mice. Overexpression of E06-scFv was anti-inflammatory: Thus, in E06-Tg mice, both peritoneal and aortic wall resident macrophages exhibited decreased inflammatory gene expression, and phenotypic switches from M1 to M2 analyzed by RNAseq and FACS. Further, in E06-Tg mice, plasma SAA levels were reduced 32%, and hepatic steatosis was also decreased (-50% in both TG and Chol), as was hepatic inflammatory gene expression. Finally, E06-scFv attenuated both a progressive increase in aortic valve gradient (via echocardiography) and calcification in aged Ldlr mice. The E06-scFv lacks functional effects of an intact antibody other than the ability to “neutralize” OxPL. Thus, these data demonstrate that OxPL are profoundly proatherogenic and proinflammatory, which E06 counteracts in vivo . Neutralizing OxPL may therefore reduce the progression of atherosclerosis and cardiovascular events and more generally, represents a novel strategy to safely attenuate inflammation.