Impact of multiple antigenic epitopes from ApoB100, hHSP60 and Chlamydophila pneumoniae on atherosclerotic lesion development in Apob(tm2Sgy)Ldlr(tm1Her)J mice

Aims: To assess whether immunizing Apob(tm2Sgy)Ldlr(tm1Her)J mice simultaneously with different atherosclerosis-related epitopes engineered in a single recombinant protein is effective in reducing atherosclerotic lesions.

Methods and results: Antigenic epitopes were incorporated into a dendroaspin scaffold: AHC (ApoB100 peptide + hHSP60 peptide [hHSP60(153-163)] + putative epitope derived from Chlamydophila pneumoniae [Cpn]) and AHHC (AHC + hHSP60(303-312)); and were compared with construct A (ApoB peptide), construct H (hHSP60(153-163)), and construct AH (ApoB100 peptide + hHSP60(153-163)). Immunization with 2 multiple-antigenic epitope constructs elicited high levels of antibodies against each epitope in Apob(tm2Sgy)Ldlr(tm1Her)J mice (apart from hHSP60(153-163), which induced a low antibody response). Histological analyses demonstrated that the mice immunized with AHHC and AHC showed significant reductions in the size of atherosclerostic lesions compared with controls (63.8% and 63.2%; P < 0.001, respectively), and significantly greater reductions in lesions size compared with those after immunization with construct A (24.9%; P < 0.01), H (26.8%; P < 0.05), and AH (42.9%; P < 0.001). Moreover, combination of 2 short Cpn peptides along with ApoB and hHSP60 peptides had an additive effect on reducing the lesion without Cpn infection. Reduction in plaque size correlated with cellular infiltration and cytokine/chemokine secretion in serum or by stimulated spleen cells as well as specific cellular immune responses when compared with controls.

Conclusions: Immunization of mice with a single construct containing multiple epitopes derived from ApoB100, hHSP60 and Cpn was more effective in reducing early atherosclerotic lesions through the induction of a specific Treg-cell response than was the construct containing either mono- or bi-epitopes. This approach offers attractive opportunities for the design of protein-based, multivalent vaccines against atherosclerosis.