Characterization and Antiatherogenic Potential of P3R99 Monoclonal Antibody Against Sulfated Glycosaminoglycans: Physicochemical and Functional Insights

Abstract

Atherosclerosis is initiated by the retention of ApoB-containing lipoproteins in the arterial wall, mediated by glycosaminoglycan chains of proteoglycans. At the Center for Molecular Immunology, we are developing the P3R99 monoclonal antibody (mAb) to target this process. This study characterizes new P3R99 mAb variants expressed in CHO-K1 and HEK-293 cell lines. We compared these variants with the parental mAb from NS0 cells using SDS-PAGE, size exclusion and cation exchange chromatography, dynamic light scattering, peptide mapping, far-UV circular dichroism, and PNGase F deglycosylation. All variants exhibited a molecular size of ~150 kDa, ~99% purity, and similar average particle sizes (12.5-13.7 nm). They displayed a high β-sheet content (>40%) and basic amino acids on the surface, with minor differences in peptide maps compared to the parental mAb. Notable differences were found in the content of acidic and basic species and glycosylation profiles. NS0-derived P3R99 had lower G0F content (10.39%), higher G1F (38.29%) and G2F (30.44%) levels, with more terminal galactose (83.07%) and sialylation (15.33%). In contrast, CHO-K1 and HEK-293 variants showed similar glycosylation patterns. Despite these differences, the antigen and atherosclerotic lesion recognition properties of the mAb were unaffected in vitro. Biodistribution studies in Sprague Dawley rats (1 mg, IV, n=3) revealed preferential accumulation of the new P3R99 variants in aortas and reduced LDL arterial retention (1 mg, IP). Passive administration of the mAbs (2 mg every three days, three IV doses, n=6-7) in a Lipofundin 20%-induced atherosclerosis NZW rabbit model also demonstrated preferential accumulation in aortas and reduced atherosclerosis, with 60% of treated rabbits not developing lesions. These results suggest that the P3R99 mAb derived from CHO-K1 and HEK-293 cells retains its antiatherogenic properties despite structural differences from the NS0-derived mAb associated with the different expression systems.