Ferroptosis of Endothelial Cells Triggered by Erythrophagocytosis Contribute to Thrombogenesis in Uremia

Although thrombosis event is the leading complication of uremia, its mechanism is largely unknown. The interaction between endothelial cells (ECs) and red blood cells (RBCs) in uremic solutes and its prothrombotic role need to be investigated. Here, we established an in vitro co-incubation model of uremic RBC and EC as well as a uremic rat model induced by adenine. We found increased erythrophagocytosis by EC accompanied with increased reactive oxygen species (ROS), lipid peroxidation and impairment of mitochondrial using flow cytometry, confocal microscopy, and electron microscopy, indicating EC undergo ferroptosis. Further investigations showed increased proteins expression of heme oxygenase-1 (HO-1) and ferritin (FTN) and labile iron pool (LIP) accumulation in EC, which could be suppressed by deferoxamine (DFO). The negative regulators of ferroptosis GPX4 and SLC7A11 were decreased in our erythrophagocytosis model and could be enhanced by ferrostatin-1 (Fer-1) or DFO. In vivo, we observed that vascular EC phagocytosed RBC and underwent ferroptosis in the kidney of the uremic rat, which could be inhibited by blocking the phagocytic pathway or inhibiting of ferroptosis. Next, we found the high tendency of thrombus formation was accompanied by erythrophagocytosis-induced ferroptosis in vitro and in vivo. Importantly, we further revealed that upregulated TMEM16F expression mediated phosphatidylserine externalization on ferroptotic EC, which contributed to a uremia-associated hypercoagulable state. Our results indicate that erythrophagocytosis triggered ferroptosis and followed phosphatidylserine exposure of EC may play a key role in uremic thrombotic complication, which may be a promising target to prevent thrombogenesis of uremia.