Sickle red blood cell‐derived extracellular vesicles activate endothelial cells and enhance sickle red cell adhesion mediated by von Willebrand factor

Abstract

Endothelial activation and sickle red blood cell (RBC) adhesion are central to the pathogenesis of sickle cell disease (SCD). Quantitatively, RBC-derived extracellular vesicles (REVs) are more abundant from SS RBCs compared with healthy RBCs (AA RBCs). Sickle RBC-derived REVs (SS REVs) are known to promote endothelial cell (EC) activation through cell signalling and transcriptional regulation at longer terms. However, the SS REV-mediated short-term non-transcriptional response of EC is unclear. Here, we examined the impact of SS REVs on acute microvascular EC activation and RBC adhesion at 2 h. Compared with AA REVs, SS REVs promoted human pulmonary microvascular ECs (HPMEC) activation indicated by increased von Willebrand factor (VWF) expression. Under microfluidic conditions, we found abnormal SS RBC adhesion to HPMECs exposed to SS REVs. This enhanced SS RBC adhesion was reduced by haeme binding protein haemopexin or VWF cleaving protease ADAMTS13 to a level similar to HPMECs treated with AA REVs. Consistent with these observations, haemin-or SS REV-induced microvascular stasis in SS mice with implanted dorsal skin-fold chambers that was inhibited by ADAMTS13. The adhesion induced by SS REVs was variable and was higher with SS RBCs from patients with increased markers of haemolysis (lactate dehydrogenase and reticulocyte count) or a concomitant clinical diagnosis of deep vein thrombosis. Our results emphasise the critical contribution made by REVs to the pathophysiology of SCD by triggering acute microvascular EC activation and abnormal RBC adhesion. These findings may

The invisible string of coagulation, complement, iron, and inflammation in sickle cell disease

“…Treating HbSS mice with rADAMTS-13 attenuates anemia/hemolysis, inflammation, organ damage, and vascular stasis induced by TNFα, H/R, and heme. A key finding of these reports is that ADAMTS13 reduced stasis and organ damage even when given after the acute trigger [51 ▪▪ ,54 ▪ ], suggesting that ADAMTS-13 is a beneficial treatment for patients during an acute VOE and may provide protection against organ damage. A double-blind, placebo-controlled, phase I clinical trial, called rADAMST-13 in Sickle Cell Disease (RAISE), is enrolling adult SCD patients (NCT 03997760) and will investigate the effect of rADAMTS13 on disease severity markers.…”

“…These findings were confirmed by two additional models of acute stasis. Using endothelialized microfluidics devices, An et al [54 ▪ ] found that extracellular vesicles derived from sickle RBCs (SS-REVs) increased endothelial VWF levels and adhesion of human sickle RBCs to the endothelium, an effect that was reversed by ADAMTS-13. Treating HbSS mice with ADAMTS-13 after exposure to either heme or SS-REVs attenuated microvascular stasis in the DSFC model [54 ▪ ].…”

The ‘scintilla’ starting vaso‐occlusion in sickle cell disease

“…In this paper, An Ran et al 1 report on keystone findings in sickle cell disease (SCD) pathophysiology. The authors explored the adhesion processes caused by human sickle erythrocytes and human pulmonary endothelial cells (HPMEC) in vitro and in vivo .…”

Emerging functional microfluidic assays for the study of thromboinflammation in sickle cell disease

“…2a,b). We have focused on standardizing these microfluidic assays to measure abnormal blood cell adhesion in whole blood samples and have uncovered significant associations with clinical phenotypes and response to treatment in SCD [56,[64][65][66][67][68][69][70][71][72][73].…”