Kuo Yu-Ju, Chung Ching-Hu, Chen Chun-Chao, Liu Ju-Chi, Chiou Kuan-Rau, Sheu Joen-Rong, Chuang Woei-Jer, Huang Tur-Fu
Division of Cardiology, Department of Internal Medicine, Shuang Ho Hospital, Taipei Medical University, Taipei 23561, Taiwan.
Department of Medicine, Mackay Medical College, New Taipei City 252, Taiwan.
Int J Mol Sci. 2025 May 9;26(10):4530. doi: 10.3390/ijms26104530.
Current αIIbβ3 antagonists are potent antithrombotic agents, their clinical use is limited by the risk of life-threatening bleeding. Emerging evidence has highlighted key mechanistic differences between thrombosis and hemostasis, opening avenues for safer antithrombotic strategies. Targeting integrin αIIbβ3 outside-in signaling has been proposed to mitigate bleeding risk; however, the short half-life of peptide-based therapeutics remains a major challenge. In this study, we developed an optimized αIIbβ3 antagonist, KGDRR-a recombinant mutant protein derived from snake venom disintegrin, incorporating an Arg55 residue within the KGD loop-through systematic structure-activity relationship (SAR) analysis. Molecular docking revealed a critical cation-π interaction between Arg55 of KGDRR and Tyr122 of the β3 subunit, stabilizing integrin αIIbβ3 in an unliganded-closed conformation. Functionally, KGDRR selectively inhibited thrombus propagation by blocking ligand binding and downstream Gα13-mediated outside-in signaling while preserving initial thrombus core formation, which is a limitation of current αIIbβ3 inhibitors. Unlike conventional antagonists, KGDRR maintained αIIbβ3 in an unliganded-closed conformation without inducing the integrin activation and conformational change that lead to immune-mediated platelet clearance and thrombocytopenia. In animal models, KGDRR effectively suppressed thrombus growth without causing thrombocytopenia or prolonging bleeding time. Furthermore, intramuscular administration of KGDRR achieved a functional half-life 3.5 times longer than that of the clinically used antithrombotic eptifibatide at equivalent antithrombotic efficacy. In conclusion, KGDRR exhibits potent antithrombotic activity with a favorable safety profile and enhanced pharmacokinetic stability. These findings position KGDRR as a promising next generation αIIbβ3 antagonist with the potential to improve clinical outcomes in antithrombotic therapy.
目前的αIIbβ3拮抗剂是强效抗血栓药物，但其临床应用因存在危及生命的出血风险而受到限制。新出现的证据突出了血栓形成和止血之间关键的机制差异，为更安全的抗血栓策略开辟了道路。有人提出靶向整合素αIIbβ3的外向信号传导以降低出血风险；然而，基于肽的治疗药物半衰期短仍然是一个重大挑战。在本研究中，我们开发了一种优化的αIIbβ3拮抗剂KGDRR，它是一种源自蛇毒去整合素的重组突变蛋白，通过系统的构效关系（SAR）分析在KGD环内引入了一个Arg55残基。分子对接显示KGDRR的Arg55与β3亚基的Tyr122之间存在关键的阳离子-π相互作用，使整合素αIIbβ3稳定在未结合的封闭构象中。在功能上，KGDRR通过阻断配体结合和下游Gα13介导的外向信号传导选择性地抑制血栓扩展，同时保留初始血栓核心形成，而这是目前αIIbβ3抑制剂的一个局限性。与传统拮抗剂不同，KGDRR使αIIbβ3保持在未结合的封闭构象中，而不诱导整合素激活和构象变化，后者会导致免疫介导的血小板清除和血小板减少。在动物模型中，KGDRR有效抑制血栓生长，而不会导致血小板减少或延长出血时间。此外，在等效抗血栓疗效下，肌肉注射KGDRR的功能半衰期比临床使用的抗血栓药物依替巴肽长3.5倍。总之，KGDRR具有强效抗血栓活性，安全性良好，药代动力学稳定性增强。这些发现使KGDRR成为一种有前景的下一代αIIbβ3拮抗剂，有可能改善抗血栓治疗的临床结果。
