Active Immunization Using TRPM2 Peptide Vaccine Attenuates Atherosclerotic Progression in a Mouse Model of Atherosclerosis.

Background/Objective: Atherosclerosis is one of the leading causes of cardiovascular diseases and mortality around the world. One exciting strategy for atherosclerosis treatment is immunotherapy, especially active immunization. Active immunization relies on the delivery of antigens in a vaccine platform to introduce humoral and cellular immunity, alleviating atherosclerotic progression. Transient receptor potential channel isoform M2 (TRPM2) is an ROS-activated Ca(2+)-permeable ion channel that can promote atherosclerosis via stimulating vascular inflammation. In the present study, we developed a strategy of active immunization with the TRPM2 E3 domain peptide in a vaccine platform, aiming to induce the endogenous production of anti-TRPM2 blocking antibody in mice in vivo, consequently inhibiting TRPM2 channel activity to alleviate atherosclerotic progression. Methods: ApoE knockout mice were fed with a high cholesterol diet to develop atherosclerosis. The mice were injected with or without the E3 peptide vaccines, followed by analysis of atherosclerotic lesion by en face Oil Red O staining of the whole aorta and histologic analysis of thin tissue sections from aortic roots. Results: The results show that immunization with a pig TRPM2 E3 region-based peptide (P1) could effectively alleviate high cholesterol diet-induced atherosclerosis in ApoE knockout mice. We worked out the best vaccine formulation for the most effective atheroprotection, namely P1 at the dose of 67.5 µg per mouse (2.5 mg/kg body weight) with aluminum salts as adjuvant. Conclusions: The present study provides a novel target TRPM2 for peptide vaccine-based anti-atherosclerotic strategy and lays the foundation for future preclinical/clinical trials using TRPM2 E3 P1 vaccine for a potential therapeutic option against atherosclerosis.