Thromb Haemost
DOI: 10.1055/a-1497-9573
Original Article

Iron-driven alterations on red blood cell-derived microvesicles amplify coagulation during hemolysis via the intrinsic tenase complex

HMVs increase thrombin generation via the intrinsic tenase complex
Laura Delvasto
1  Sanquin Research, Amsterdam, Netherlands (Ringgold ID: RIN159217)
Dorina Roem
1  Sanquin Research, Amsterdam, Netherlands (Ringgold ID: RIN159217)
Kamran Bakhtiari
2  Plasma Proteins, Sanquin Research, Amsterdam, Netherlands
Gerard J. van Mierlo
1  Sanquin Research, Amsterdam, Netherlands (Ringgold ID: RIN159217)
Joost Meijers
3  Sanquin Bloedvoorziening, Amsterdam, Netherlands (Ringgold ID: RIN1193)
4  Sanquin Research, Amsterdam, Netherlands (Ringgold ID: RIN159217)
5  Department of Pediatric Immunology, Rheumatology and Infectious Diseases, Amsterdam UMC Locatie AMC, Amsterdam, Netherlands (Ringgold ID: RIN26066)
Sacha S. Zeerleder
6  Department of Immunopathology, Sanquin-AMC Landsteiner Laboratory, Amsterdam, Netherlands
7  Department of Hematology, Academic Medical Center, Amsterdam, Netherlands
› Author Affiliations

Hemolytic disorders characterized by complement-mediated intravascular hemolysis, such as autoimmune hemolytic anemia and paroxysmal nocturnal hemoglobinuria, are often complicated by life-threatening thromboembolic complications. Severe hemolytic episodes result in the release of red blood cell (RBC)-derived pro-inflammatory and oxidatively reactive mediators (e.g. extracellular hemoglobin, heme and iron) into plasma. Here, we studied the role of these hemolytic mediators in coagulation activation by measuring FXa and thrombin generation in the presence of RBC lysates. Our results show that hemolytic microvesicles (HMVs) formed during hemolysis stimulate thrombin generation through a mechanism involving FVIII and FIX, the so-called intrinsic tenase complex. Iron scavenging during hemolysis using deferoxamine decreased the ability of the HMVs to enhance thrombin generation. Furthermore, the addition of ferric chloride (FeCl3) to plasma propagated thrombin generation in a FVIII and FIX-dependent manner suggesting that iron positively affects blood coagulation. Phosphatidylserine (PS) blockade using lactadherin and iron chelation using deferoxamine reduced intrinsic tenase activity in a purified system containing HMVs as source of phospholipids confirming that both PS and iron ions contribute to the procoagulant effect of the HMVs. Finally, the effects of FeCl3 and HMVs decreased in the presence of ascorbate and glutathione indicating that oxidative stress plays a role in hypercoagulability. Overall, our results provide evidence for the contribution of iron ions derived from hemolytic RBCs to thrombin generation. These findings add to our understanding of the pathogenesis of thrombosis in hemolytic diseases.

Publication History

Received: 04 November 2020

Accepted after revision: 26 April 2021

Publication Date:
03 May 2021 (online)

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