Abstract
Background
Proprotein convertase subtilisin/kexin 9 (PCSK9) promotes hypercholesterolemia through reducing protein level of liver low-density lipoprotein (LDL) receptor (LDLR). Currently, PCSK9 inhibition is known as an efficient lipid-lowering approach.
Purpose
Here, we constructed a liposomal anti-PCSK9 vaccine, and evaluated its therapeutic effects on dyslipidemia and atherosclerosis in atherosclerotic mice.
Methods
Liposomal anti-PCSK9 vaccine was prepared viaattaching immunogenic peptide, termed Immunogenic Fused PCSK9-Tetanus (IFPT), on the surface of nanoliposome carriers by using DSPE-PEG-Maleimide lipid (L-IFPT). The L-IFPT formulation was adsorbed to Alum adjuvant (L-IFPTA+) and administrated subcutaneously four times with a bi-weekly interval in hypercholesterolemic C57BL/6 mice. Plasma levels of anti-PCSK9 antibody, plasma concentration of PCSK9 protein, effect of anti-PCSK9 antibody on PCSK9-LDLR interaction, protein levels of liver LDLR, lipid profile, as well as atherosclerotic lesion size and severity were measured in the vaccinated hypercholesterolemic mice. To determine immune safety, Inflammatory response was measured by evaluating IFN-γ and IL-10 producing splenic cells using ELISpot assay.
Results
L-IFPTA+vaccine promoted the high IgG antibody response against PCSK9 peptide in the hypercholesterolemic mice. L-IFPTA+-induced antibodies targeted plasma PCSK9 and thereby decreased plasma consecration of PCSK9, which was associated with the reduced PCSK9-LDLR interaction and the increased liver levels of LDLR protein. Inhibitory effect of L-IFPTA+vaccine was accompanied with a significant reduction of plasma levels of total cholesterol (TC), LDL-C, and VLDL-C. Interestingly, L-IFPTA+vaccine could considerably reduce atherosclerotic lesion size and intima to media thicknessin hypercholesterolemic mice. Long-term evaluation of hypercholesterolemic vaccinated mice showed that L-IFPTA+vaccine was able to promote a long-lasting anti-PCSK9 antibody titration, which was paralleled by a significant reduction of LDL-C over 16 weeks post prime immunization (Figure). Splenocytes isolated from vaccinated mice indicated the reduced IFN-γ producing cells and the elevated IL-10 producing cells, suggesting immune safety of liposomal anti-PCSK9 vaccine.
Figure 1
Conclusions
L-IFPTA+vaccine induced efficient anti-PCSK9 antibodies which could exert long-term therapeutic effect on hypercholesterolemia and atherosclerosis in mice, revealing a feasible vaccine-based approach for managing hypercholesterolemia and cardiovascular disease.
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