The specific objective of this proposal is to explore how PCSK9 derails CD8+ T cell activation and to unveil the molecular mechanisms related to immunometabolic cellular reprogramming occurring during CD8+ T cell activation that are affected by PCSK9. To pursue this objective, the research plan proposes to explore whether PCSK9 manipulation reflects into impaired CD8+ T cell activation in vitro and in vivo. Via liver genetic editing of potential targets of PCSK9 (including the LDL-R and CD36) as well as the use of CD8+ T cell tracing in experimental models lacking PCSK9 globally or selective in the liver we plan to specifically separate the impact of PCSK9 deficiency on hypercholesterolemia with that on T cell immunometabolic reprogramming during activation. In addition, to improve the translational potential of the project, changes in CD8+ T cell profile will be tested in an experimental model with human adaptive immune system co-expressing a human gain of function PCSK9 protein isoform.
This proposal is structured in 4 workpackages directed at:
1) Profile the immunometabolic signature of T lymphocytes and of the other CD45+ cells in the bone marrow, in the circulation and in the lymphoid organs of experimental models lacking PCSK9 (globally in the liver or in bone marrow cells).
2) Evaluate how the modification in the immunometabolic signature related to PCSK9 deficiency are reflected into functional changes in CD8+ T cell.
3) Explore how the alteration of LDL-R or of CD36 expression in immune cells or in the liver impact the immunometabolic role of PCSK9 in CD8+ T cell related responses.
4) Translate the immunometabolic role of PCSK9 in humans by exploring human CD8+ cell activation in humanized animal models expressing a gain of function human isoform of PCSK9 (D374Y) and in subjects with a loss of function mutation of PCSK9 (R46L) compared to age and sex matched controls.