Unraveling immune checkpoint inhibitors effects on atherosclerosis: mechanisms and preventive approaches

Abstract Background Immune checkpoint inhibitors (ICIs) represent a novel and rapidly evolving field in cancer treatment. Despite increasing reports of accelerated atherosclerosis and ICI-related atherosclerotic cardiovascular (CV) events in clinical studies and case reports, there is a notable lack of data concerning the underlying mechanisms, appropriate monitoring, and potential interventions. Objectives To explore the role of ICIs in triggering and/or accelerating the atherosclerotic process, with a specific focus on the involvement of CD8+ T-cells. Additionally, we aimed to evaluate and compare the potential beneficial effects of statins and Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) inhibitors on atherosclerosis under ICIs treatment. Methods Thirty 8-week-old C57BL mice were divided into six groups as follows: (1) Control, normal diet; (2) Control, atherogenic diet; (3) Atherogenic diet + anti PD-1; (4) Atherogenic diet + statins + anti-PD1; (5) Atherogenic diet + PCSK9-i + anti PD-1; (6) Atherogenic diet + PCSK9 inhibitors. At 16 weeks, the carotid arteries and heart were removed for histological examination, and serum was withdrawn for blood work and further analysis. Results Anti-PD1 treatment resulted in extensive lymphocytic infiltration of the carotid intima, primarily constituted of CD8+ T cells. This infiltration was significantly attenuated when statins or PCSK-9 inhibitors were used in conjunction with anti-PD1 treatment. Serum analysis for CD4+ and CD8+ T cells by ELISA revealed no difference in CD4+ abundance between the groups. However, plasma CD8+ T cells were significantly increased with anti-PD1 treatment, and furthermore, when PCSK9 inhibitors were used in combination; but not when statins were used. Conclusion The induction of CD8+ T cell infiltration in the arterial carotid walls by anti-PD-1 was prevented with the use of either statins or PCSK9 inhibitors. In the plasma, while statins reduced the hyper-expression of CD8+ T cells observed under PD-1 treatment, PCSK9 inhibitors enhanced this expression. This may provide a first indication of the potential benefit of PCSK9 inhibitor treatment for both preventing arterial inflammation and enhancing the desired anti-tumor immune response under ICIs treatment. Figure legend: 1A. A cross-section of the carotid artery after 16 weeks of treatment, stained with H&E. Magnification is X100. 1B. A cross-section of the carotid artery after 16 weeks of treatment, stained with anti-CD8 Ab. Magnification is X100. 1C. quantitative CD8+ T cells staining in the carotid arteries. 1D. quantitative results of ELISA for plasma CD8+ T cells.