| Contribution of platelet dysfunction to bleeding in Ehlers Danlos syndrome Mariia Kumskova. |
Abstract
Contribution of platelet dysfunction to bleeding in Ehlers Danlos syndrome
Mariia Kumskova, Gagan D. Flora, Manasa K. Nayak, Madankumar Ghatge, Ivan Budnik, Rakesh B. Patel, Aditi Jain, Janice Staber Steven R. Lentz, Anil K. Chauhan
Introduction: People with Ehlers–Danlos syndrome (EDS) exhibit an increased susceptibility to bleeding complications. Despite the long-recognized association between EDS and bleeding predisposition, we still lack a definitive understanding of the underlying mechanisms contributing to bleeding diathesis in people with EDS. This study aims to characterize the platelet function in a cohort of people with EDS and a murine EDS model.
Methods: We recruited a cohort of people with different types of EDS, including classical, classical-like, hypermobile, and vascular. All people with EDS were matched with healthy controls by age and gender. All participants were included in accordance with the University of Iowa Institutional Review Board-approved protocol. The bleeding tendency in all study participants was assessed using the International Society of Thrombosis and Haemostasis bleeding assessment tool (ISTH-BAT). We employed COL5A1+/− mice as a murine model of the classical type of EDS. The function of human and mouse platelets was evaluated using standardized agonist-induced in vitro assays.
Results: The mean ISTH-BAT score was 0.1 in healthy controls and 9.2 in people with EDS (P < 0.001). An abnormal ISTH-BAT score was observed in 33 out of 53 (62%) people with EDS and 0 of 53 healthy controls (P < 0.001). Evaluation of platelets from people with EDS demonstrated reduced aggregation and αIIbβ3 activation (with normal αIIbβ3 surface expression) in response to stimulation with collagen, collagen-related peptide (CRP), and thrombin receptor activator peptide-6 (TRAP), compared to healthy controls. Evaluation of collagen receptor expression on the surface of resting platelets showed a mild deficiency of GPVI in people with EDS compared to healthy controls (P < 0.001), while the integrin α2 levels were similar in both groups (P = 0.152). Analysis of GPVI downstream signaling revealed defects in LAT (Y220), Syk (Y525/526), PLCγ2 (Y1217), and talin (S425) phosphorylation in people with EDS (P < 0.05 vs. healthy controls), suggesting a defect in platelet inside-out signaling. Secretion of dense and α-granules as well as phosphatidylserine surface exposure upon dual activation with CRP and TRAP-6 were comparable between people with EDS and healthy subjects. In accordance with human EDS platelets, COL5A1+/− mice demonstrated a bleeding tendency characterized by prolonged tail-bleeding time in both sexes (P < 0.05 vs. wild-type control). Platelet function testing showed that COL5A1+/− mouse platelets recapitulated the abnormalities detected in people with EDS platelets.
Conclusions: Our data affirm the observation that people with EDS exhibit an increased risk of hemorrhagic complications. EDS platelets exhibit reduced baseline GPVI expression associated with decreased agonist-induced platelet aggregation, αIIbβ3 activation, and impaired signaling.
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