Résumé
Hemolysis is a known risk factor for thrombosis resulting in critical limb ischemia and microcirculatory disturbance and organ failure. Intravasal hemolysis may lead to life-threatening complications due to uncontrolled thrombo-inflammation. Until now, conventional antithrombotic therapies failed to control development and progression of these thrombotic events. Thus, the pathophysiology of these thrombotic events needs to be investigated to unravel underlying pathways and thereby identify targets for novel treatment strategies.
Here we used classical experimental set-ups as well as high-end flow cytometry, metabolomics and lipidomic analysis to in-depth analyze the effects of hemin on platelet physiology and morphology.
Hemin does strongly and swiftly induce platelet activation and this process is modulated by the sGC-cGMP-cGKI signaling axis. cGMP modulation also reduced the pro-aggregatory potential of plasma derived from patients with hemolysis. Furthermore, hemin-induced platelet death evokes distinct platelet subpopulations. Typical cell death markers, such as ROS, were induced by hemin-stimulation and the platelet lipidome was specifically altered by high hemin concentration. Specifically, arachidonic acid derivates, such as PGE2, TXB2 or 12-HHT, were significantly increased. Balancing the cGMP levels by modulation of the sGC-cGMP-cGKI axis diminished the ferroptotic effect of hemin.
We found that cGMP modulates hemin-induced platelet activation and thrombus formation in vitro and cGMP effects hemin-mediated platelet death and changes in the platelet lipidome. Thus, it is tempting to speculate that modulating platelet cGMP levels may be a novel strategy to control thrombosis and critical limb ischemia in patients with hemolytic crisis.
Graphical presentation of the signaling pathways effected by hemin (red arrows) and modulated by NO/riociguat (blue arrows) and their involvement on platelet activation, degranulation and aggregation as well as hemin-mediated cell death. [Display omitted]
•cGMP modulates hemin-induced platelet activation and thrombus formation in vitro.•Hemin induces platelet death.•Free hemin causes changes in the platelet lipidome.•Hemin-induced platelet death and lipidome changes are inhibited by cGMP modulation.