Engineering chimeric PCSK9 for a vaccine against atherosclerosis

Area of Science:

• Immunology
• Cardiovascular Science
• Vaccine Development

Background:

• Cardiovascular diseases, particularly atherosclerosis, are a leading global cause of mortality.
• Lowering serum low-density lipoprotein cholesterol (LDL-C) is crucial for reducing cardiovascular risk.
• Targeting proprotein convertase 9 (PCSK9) is an effective strategy, with current methods including genome editing and monoclonal antibodies.

Purpose of the Study:

• To develop a novel vaccine strategy against PCSK9 to overcome challenges of immunogenicity and B cell tolerance.
• To create a chimeric PCSK9 vaccine that elicits a strong humoral immune response while minimizing T cell reactivity against self-antigens.
• To evaluate the long-term efficacy of this chimeric vaccine in an atherosclerosis mouse model.

Main Methods:

• Design and development of a chimeric PCSK9 construct maintaining surface epitopes but lacking natural T cell epitopes.
• Vaccination of mice with the chimeric PCSK9 construct.
• Assessment of humoral immunity (PCSK9-specific antibodies) and T cell reactivity.
• Evaluation of therapeutic effects in an established atherosclerosis mouse model, measuring circulating PCSK9, cholesterol levels, and atherosclerotic burden in the aorta.

Main Results:

• The chimeric PCSK9 vaccine successfully elicited PCSK9-specific antibodies, comparable to human vaccines, with reduced T cell reactivity.
• Vaccination led to sustained reduction in circulating PCSK9 and cholesterol levels for over 20 weeks in the atherosclerosis model.
• A significant decrease in atherosclerotic disease burden within the aorta was observed, demonstrating therapeutic improvement.

Conclusions:

• A rationally designed chimeric PCSK9 vaccine can overcome immune tolerance and generate a potent humoral immune response.
• This vaccine strategy offers a promising, long-lasting therapeutic approach for atherosclerosis by targeting endogenous PCSK9.
• The study provides proof-of-concept for designing vaccines against self-antigens for treating chronic diseases.