Engineering chimeric PCSK9 for a vaccine against atherosclerosis

Cardiovascular diseases, especially atherosclerosis, are the major cause of death in the modern era. In most cases, amelioration is achieved by decreasing the concentration of LDL cholesterol in blood, using statins or monoclonal antibodies targeting PCSK9, which are highly efficient, but are costly and requires bimonthly administration. Vaccination against PCSK9 represents an attractive alternative with potentially long-lasting efficiency, but has to overcome the challenge of autoimmune reactivity against an endogenous protein to prevent healthy tissue damage. We developed an autologous chimeric vaccine against PCSK9, which triggers a B cell immune response to produce neutralizing antibodies but avoids induction of self antigen mediated T cell cytotoxicity. We demonstrated in atherosclerosis murine model that vaccination generated an adequate humoral immune response with the effect persistent over 24°weeks, observed in lower circulating PCSK9, lower cholesterol and reduced atherosclerotic disease burden in the aortas. This is a proof of concept study for a therapeutic amelioration of atherosclerosis, which also provides a perspective on the rational design of a vaccine against endogenous proteins. Overall design: 5 female 8-10 weeks old Apoe-/- mice (strain B6.129P2 Apoetm1Unc/J; Charles River) per experimental group were intramuscularly injected plasmid DNA (empty pCG1 vector and pCG1-chPCSK9-tox plasmid), complexed with jetPEI in vivo transfection reagent. Mice were injected 3 times with 2 weeks in-between injections. 24 weeks after beginning of the experiment animals were sacrificed and liver tissue was taken for homogenization and total RNA was extracted using TriPure Isolation Reagent (Roche) according to manufacturer's instructions. Collected RNA from animal tissue was pooled in 4 replicates and then sent for bulk RNA sequencing.