Abstract
Background Although thrombosis events are the leading complication of uremia, their 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.
Methods and Results Here, we established an in vitro co-incubation model of uremic RBC and EC as well
as a uremic rat model induced by adenine. Using flow cytometry, confocal microscopy,
and electron microscopy, we found increased erythrophagocytosis by EC accompanied
by increased reactive oxygen species, lipid peroxidation, and impairment of mitochondria,
indicating that ECs undergo ferroptosis. Further investigations showed increased proteins'
expression of heme oxygenase-1 and ferritin and labile iron pool accumulation in EC,
which could be suppressed by deferoxamine (DFO). The ferroptosis-negative regulators
glutathione peroxidase 4 and SLC7A11 were decreased in our erythrophagocytosis model
and could be enhanced by ferrostatin-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 ferroptosis. Next,
we found that 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.
Conclusion Our results indicate that erythrophagocytosis-triggered ferroptosis followed by phosphatidylserine
exposure of EC may play a key role in uremic thrombotic complications, which may be
a promising target to prevent thrombogenesis of uremia.
Keywords
erythrophagocytosis - ferroptosis - endothelial cell - thrombosis - uremia
