Chen Yiyao Catherine, Louis Naveen Eugene Louis Richard, Huang Angela, Sun Allan, Dupuy Alexander, Moldovan Laura, Pelaia Tiana, Ren Jianfang, Cohen Taylor S, Gilbert Sarah C, Tran Huyen, Peter Karlheinz, McFadyen James D, Ju Lining Arnold
School of Biomedical Engineering, The University of Sydney, Darlington, NSW, Australia.
Atherothrombosis and Vascular Biology, Baker Heart and Diabetes Institute, Melbourne, VIC, Australia.
Blood. 2025 Jul 24;146(4):496-503. doi: 10.1182/blood.2024027675.
Rare thrombotic events associated with ChAdOx1 nCoV-19 (ChAdOx1) vaccination have raised concerns; however, the underlying mechanisms remain elusive. Here, we report a novel biophysical mechanism by which ChAdOx1 directly interacts with platelets under arterial shear conditions, potentially contributing to postvaccination arterial thrombosis. Using microfluidic post assays, we demonstrate that ChAdOx1 induces shear-dependent platelet aggregation, distinct from conventional von Willebrand factor-mediated adhesion. This interaction is mediated by platelet integrin αIIbβ3 and requires biomechanical activation, explaining the absence of significant binding under static conditions. Molecular dynamics simulations and docking studies reveal preferential binding of ChAdOx1's penton arginine-glycine-aspartic acid (RGD) motif to the activated conformation of αIIbβ3. Inhibiting integrin αIIbβ3 completely abolishes ChAdOx1-induced platelet aggregation, whereas blocking glycoprotein (GP) Ib has minimal effect, confirming a mechanism that bypasses the conventional GPIb-dependent platelet adhesion pathway. Mutagenesis of the RGD motif to AAA eliminates platelet binding, verifying the specificity of this interaction. These findings provide a potential explanation for the association between ChAdOx1 vaccination and arterial thrombotic events, distinct from vaccine-induced immune thrombotic thrombocytopenia. Our results highlight the importance of considering biomechanical factors in vaccine-related thrombotic complications and suggest that shear-dependent integrin activation may be another determinant in the pathogenesis of these rare adverse events.
与ChAdOx1 nCoV-19（ChAdOx1）疫苗接种相关的罕见血栓形成事件引发了人们的关注；然而，其潜在机制仍不清楚。在此，我们报告了一种新的生物物理机制，通过该机制ChAdOx1在动脉剪切条件下直接与血小板相互作用，这可能导致疫苗接种后动脉血栓形成。使用微流控后分析，我们证明ChAdOx1诱导剪切依赖性血小板聚集，这与传统的血管性血友病因子介导的黏附不同。这种相互作用由血小板整合素αIIbβ3介导，并且需要生物力学激活，这解释了在静态条件下不存在显著结合的原因。分子动力学模拟和对接研究揭示了ChAdOx1的五聚体精氨酸-甘氨酸-天冬氨酸（RGD）基序与αIIbβ3的活化构象的优先结合。抑制整合素αIIbβ3完全消除了ChAdOx1诱导的血小板聚集，而阻断糖蛋白（GP）Ib的影响最小，证实了一种绕过传统的GPIb依赖性血小板黏附途径的机制。将RGD基序突变为AAA消除了血小板结合，验证了这种相互作用的特异性。这些发现为ChAdOx1疫苗接种与动脉血栓形成事件之间的关联提供了一种潜在解释，这与疫苗诱导的免疫性血栓性血小板减少症不同。我们的结果强调了在疫苗相关血栓形成并发症中考虑生物力学因素的重要性，并表明剪切依赖性整合素激活可能是这些罕见不良事件发病机制中的另一个决定因素。
