Exploring novel mechanisms of hemostasis activation in sickle cell disease: focus on the PDPN:CLEC-2 pathway

Abstract

Hypercoagulability is a hallmark of sickle cell disease (SCD), and its pathophysiology is related to the concomitant activation of hemostasis and innate immunity, in a process known as immunothrombosis. The mechanisms involved include the generation of neutrophil extracellular traps (NETs), complement activation, and the expression of tissue factor on monocytes and extracellular vesicles (EVs). Recently, the podoplanin/CLEC-2 pathway has been highlighted as an important pathway in coagulation activation and thrombosis. Podoplanin (PDPN) is a membrane protein expressed on monocytes and its only ligand is CLEC-2, which is primarily found on platelets. Preliminary results from our study indicate that the PDPN/CLEC-2 pathway is activated in the context of SCD, showing elevated levels of PDPN and CLEC-2 in plasma and/or cellular samples. Additionally, our preliminary in vitro experiments suggested that coagulation is activated in plasma samples stimulated with recombinant PDPN. In addition, precise laboratory methods to explore hypercoagulability in SCD remain a challenge, since more sensitive tests to detect coagulation activation in this context are lacking. Therefore, the objective of this project is to explore the role of PDPN in the hypercoagulability state observed in SCD, by developing assays capable of detecting the putative contribution of PDPN to hemostasis activation. In addition, to correlate these results with more specific assays such as tissue factor-dependent procoagulant activity and thrombin generation. These data can contribute to a better characterization of hypercoagulability in SCD and its relationship with the PDPN/CLEC-2 pathway.