Vadivel K, Kumar Y, Ogueli G I, Ponnuraj S M, Wongkongkathep P, Loo J A, Bajaj M S, Bajaj S P
Department of Orthopaedic Surgery, University of California, Los Angeles, CA, USA.
Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA.
J Thromb Haemost. 2016 Dec;14(12):2509-2523. doi: 10.1111/jth.13538. Epub 2016 Nov 19.
Essentials Current antifibrinolytics - aminocaproic acid and tranexamic acid-can cause seizures or renal injury. KD1 -K , aprotinin and tranexamic acid were tested in a modified mouse tail-amputation model. S2'-subsite variations between human and mouse factor XIa result in vastly different inhibition profiles. KD1 -K reduces blood loss and D-dimer levels in mouse with unobserved seizures or renal injury.
Background Using tissue factor pathway inhibitor (TFPI)-2 Kunitz domain1 (KD1), we obtained a bifunctional antifibrinolytic molecule (KD1 -K ) with C-terminal lysine (kringle domain binding) and P2'-residue arginine (improved specificity towards plasmin). KD1 -K strongly inhibited human plasmin (hPm), with no inhibition of human kallikrein (hKLK) or factor XIa (hXIa). Furthermore, KD1 -K reduced blood loss comparable to aprotinin in a mouse liver-laceration model of organ hemorrhage. However, effectiveness of these antifibrinolytic agents in a model of hemorrhage mimicking extremity trauma and their inhibition efficiencies for mouse enzymes (mPm, mKLK or mXIa) remain to be determined. Objective To determine potential differences in inhibition constants of various antifibrinolytic agents against mouse and human enzymes and test their effectiveness in a modified mouse tail-amputation hemorrhage model. Methods/Results Unexpectedly, mXIa was inhibited with ~ 17-fold increased affinity by aprotinin (K ~ 20 nm) and with measurable affinity for KD1 -K (K ~ 3 μm); in contrast, KD1 -V inhibited hXIa or mXIa with similar affinity. Compared with hPm, mPm had ~ 3-fold reduced affinity, whereas species specificity for hKLK and mKLK was comparable for each inhibitor. S2'-subsite variations largely accounted for the observed differences. KD1 -K and aprotinin were more effective than KD1 -V or tranexamic acid in inhibiting tPA-induced mouse plasma clot lysis. Further, KD1 -K was more effective than KD1 -V and was comparable to aprotinin and tranexamic acid in reducing blood loss and D-dimer levels in the mouse tail-amputation model. Conclusions Inhibitor potencies differ between antifibrinolytic agents against human and mouse enzymes. KD1 -K is effective in reducing blood loss in a tail-amputation model that mimics extremity injury.
要点 当前的抗纤溶药物——氨基己酸和氨甲环酸——可导致癫痫发作或肾损伤。在改良的小鼠断尾模型中对KD1 -K、抑肽酶和氨甲环酸进行了测试。人源和鼠源因子XIa之间S2'-亚位点的差异导致了截然不同的抑制谱。KD1 -K可减少小鼠的失血和D-二聚体水平，且未观察到癫痫发作或肾损伤。
背景 使用组织因子途径抑制剂（TFPI）-2的Kunitz结构域1（KD1），我们获得了一种双功能抗纤溶分子（KD1 -K），其C端为赖氨酸（kringle结构域结合），P2'-残基为精氨酸（对纤溶酶的特异性提高）。KD1 -K强烈抑制人纤溶酶（hPm），但不抑制人激肽释放酶（hKLK）或因子XIa（hXIa）。此外，在器官出血的小鼠肝裂伤模型中，KD1 -K减少的失血量与抑肽酶相当。然而，这些抗纤溶药物在模拟肢体创伤的出血模型中的有效性及其对小鼠酶（mPm、mKLK或mXIa）的抑制效率仍有待确定。目的 确定各种抗纤溶药物对小鼠和人源酶抑制常数的潜在差异，并在改良的小鼠断尾出血模型中测试其有效性。方法/结果 出乎意料的是，抑肽酶对mXIa的抑制亲和力增加了约17倍（K约为20nm），对KD1 -K也有可测量的亲和力（K约为3μm）；相比之下，KD1 -V以相似的亲和力抑制hXIa或mXIa。与hPm相比，mPm的亲和力降低了约3倍，而每种抑制剂对hKLK和mKLK的物种特异性相当。S2'-亚位点的差异在很大程度上解释了观察到的差异。在抑制tPA诱导的小鼠血浆凝块溶解方面，KD1 -K和抑肽酶比KD1 -V或氨甲环酸更有效。此外，在小鼠断尾模型中，KD1 -K在减少失血量和D-二聚体水平方面比KD1 -V更有效，与抑肽酶和氨甲环酸相当。结论 抗纤溶药物对人源和鼠源酶的抑制效力不同。KD1 -K在模拟肢体损伤的断尾模型中能有效减少失血量。
