Abstract 466: Therapeutic Immunization with an Antiglycosaminoglycan Antibody Reduces Atherosclerotic Lesion Progression in Apolipoprotein E-Deficient Mice

Abstract

Subendothelial retention of apoB-containing lipoproteins by interaction with glycosaminoglycan-side chains of proteoglycans is considered the key initiating step of atherogenesis. Previously, we characterized the antiatherogenic properties of the chimeric mAb chP3R99, which binds sulfated GAG, inhibits LDL-chondroitin sulfate (CS) association, and abrogates LDL oxidation in vitro and in vivo. In preventive settings, rabbits and mice immunized with this mAb showed reduced atherosclerotic lesions, related with the induction of anti-chondroitin sulfate (CS) antibodies. Now we focus in define the immunization schedule which can induce in apolipoprotein E-deficient (apoE-/-) the highest anti-CS antibody response and the greater reduction of atherosclerotic lesion progression. ApoE - / - mice (6-8 wk. old) fed a chow diet received four s.c. injections of 50 or 200 μg of chP3R99 mAb. Autologous antichondroitin sulfate (CS) antibody response was evaluated in sera by ELISA. Mice who were immunized with 200 μg generated a significant higher response against CS than the ones that received 50 μg. Then, to evaluate the association of the induction of a higher anti-CS response in the atherosclerotic lesion progression, apoE-/- mice fed with a high-fat high-cholesterol diet from 4 to 18 wk. of age, received 6 doses of 50, 100 or 200 μg of the mAb starting when 5% of the aortic area was covered by lesions. Animals were sacrificed and aortas isolated to determine the presence of lesions by histologic studies. Mean aortic lesion areas of 50 and 100 μg chP3R99-treated mice were significant reduced by ~40% in comparison with mice treated with an isotype-matched control mAb. In contrast, 62% reduction in total lesion area was observed in mice treated with 200 μg of chP3R99. Again, there was an association between the level of anti-CS antibody response and the reduction of atherosclerotic lesion progression. In conclusion, this study demonstrated the dose dependence of the anti-CS antibody response and its relationship with the arresting of the atherosclerotic progression induced by chP3R99 mAb immunization. Our results also supports the potential use of this antiglycosaminoglycan antibody-based immunotherapy as a novel approach to target advanced atherosclerosis