Erythroid lineage [Jak2.sup.V617F] expression promotes atherosclerosis through erythrophagocytosis and macrophage ferroptosis

Elevated hematocrit is associated with cardiovascular risk; however, the causality and mechanisms are unclear. The [JAK2.sup.V617F] ([JAK2.sup.VF]) mutation increases cardiovascular risk in myeloproliferative disorders and in clonal hematopoiesis. [JAK2.sup.VF] mice with elevated WBCs, platelets, and RBCs display accelerated atherosclerosis and macrophage erythrophagocytosis. To investigate whether selective erythroid [JAK2.sup.VF] expression promotes atherosclerosis, we developed hyperlipidemic erythropoietin receptor Cre mice that express [JAK2.sup.VF] in the erythroid lineage (VFEpoR mice). VFEpoR mice without elevated blood cell counts showed increased atherosclerotic plaque necrosis, erythrophagocytosis, and ferroptosis. Selective induction of erythrocytosis with low-dose erythropoietin further exacerbated atherosclerosis with prominent ferroptosis, lipid peroxidation, and endothelial damage. VFEpoR RBCs had reduced antioxidant defenses and increased lipid hydroperoxides. Phagocytosis of human or murine WT or [JAK2.sup.VF] RBCs by WT macrophages induced ferroptosis, which was prevented by the ferroptosis inhibitor liproxstatin-1. Liproxstatin-1 reversed increased atherosclerosis, lipid peroxidation, ferroptosis, and endothelial damage in VFEpoR mice and in [JAK2.sup.VF] chimeric mice simulating clonal hematopoiesis, but had no impact in controls. Erythroid lineage [JAK2.sup.VF] expression led to qualitative and quantitative defects in RBCs that exacerbated atherosclerosis. Phagocytosis of RBCs by plaque macrophages promoted ferroptosis, suggesting a therapeutic target for reducing RBC-mediated cardiovascular risk.
Introduction Elevated hematocrit is associated with increased atherothrombotic cardiovascular disease (ACD), the number one cause of death and disability in Western societies (1, 2). Observational studies have shown that human [...]