Irish Centre for Vascular Biology, School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland, Dublin, Ireland.
Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada.
J Thromb Haemost. 2024 Oct;22(10):2752-2760. doi: 10.1016/j.jtha.2024.06.023. Epub 2024 Jul 10.
von Willebrand factor (VWF)-R1205H variant (Vicenza) results in markedly enhanced VWF clearance in humans that has been shown to be largely macrophage-mediated. However, the biological mechanisms underlying this enhanced clearance remain poorly understood.
This study aimed to investigate the roles of (i) specific VWF domains and (ii) different macrophage receptors in regulating enhanced VWF-R1205H clearance.
In vivo clearance of full-length and truncated wild-type (WT)-VWF and VWF with R1205 substitutions was investigated in VWF mice. Plate-binding assays were employed to characterize VWF binding to purified scavenger receptor class A member 1 (SR-AI), low-density lipoprotein receptor-related protein-1 (LRP1) cluster II or cluster IV receptors, and macrophage galactose-type lectin.
In full-length VWF missing the A1 domain, introduction of R1205H led to significantly enhanced clearance in VWF mice compared with WT-VWF missing the A1 domain. Importantly, R1205H in a truncated VWF-D'D3 fragment also triggered increased clearance compared with WT-VWF-D'D3. Additional in vivo studies demonstrated that VWF-R1205K (which preserves the positive charge at 1205) exhibited normal clearance, whereas VWF-R1205E (which results in loss of the positive charge) caused significantly enhanced clearance, pinpointing the importance of the positive charge at VWF-R1205. In vitro plate-binding studies confirmed increased VWF-R1205H interaction with SR-AI compared with WT-VWF. Furthermore, significantly enhanced VWF-R1205H binding to LRP1 cluster IV (P < .001) and less marked enhanced binding to LRP1 cluster II (P = .034) was observed. In contrast, VWF-R1205H and WT-VWF demonstrated no difference in binding affinity to macrophage galactose-type lectin.
Disruption of the positive charge at amino acid R1205 causes conformational changes in the VWF-D'D3 domains and triggers enhanced LRP1-mediated and SR-AI-mediated clearance.
血管性血友病因子（VWF）-R1205H 变异体（Vicenza）导致人类 VWF 的清除率显著增加，而这种清除率主要是由巨噬细胞介导的。然而，这种增强的清除作用背后的生物学机制仍知之甚少。
本研究旨在探讨（i）VWF 特定结构域和（ii）不同巨噬细胞受体在调节增强的 VWF-R1205H 清除中的作用。
在 VWF 小鼠中研究全长和截断野生型（WT）-VWF 以及具有 R1205 取代的 VWF 的体内清除率。采用平板结合实验研究 VWF 与纯化的清道夫受体 A 成员 1（SR-AI）、低密度脂蛋白受体相关蛋白 1（LRP1）簇 II 或簇 IV 受体以及巨噬细胞半乳糖型凝集素的结合。
在缺少 A1 结构域的全长 VWF 中，与缺少 A1 结构域的 WT-VWF 相比，引入 R1205H 导致清除率显著增加。重要的是，在截断的 VWF-D'D3 片段中引入 R1205H 也会导致清除率增加。进一步的体内研究表明，VWF-R1205K（保留 1205 位的正电荷）表现出正常的清除率，而 VWF-R1205E（导致正电荷丧失）导致清除率显著增加，这表明 VWF-R1205 的正电荷非常重要。体外平板结合研究证实，与 WT-VWF 相比，VWF-R1205H 与 SR-AI 的相互作用增强。此外，还观察到 VWF-R1205H 与 LRP1 簇 IV 的结合显著增强（P<.001），与 LRP1 簇 II 的结合增强幅度较小（P=.034）。相比之下，VWF-R1205H 和 WT-VWF 与巨噬细胞半乳糖型凝集素的结合亲和力没有差异。
在氨基酸 R1205 处破坏正电荷会导致 VWF-D'D3 结构域构象发生变化，并触发增强的 LRP1 介导和 SR-AI 介导的清除。
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