Laboratory for Pharmaceutical Biology, Faculty of Pharmaceutical Sciences, Katholieke Universiteit Leuven, Belgium.
Thromb Res. 2011 Jul;128(1):68-76. doi: 10.1016/j.thromres.2011.01.011. Epub 2011 Mar 9.
PAI-1 is the main physiological inhibitor of t-PA and u-PA. Elevated PAI-1 levels have been implicated in the pathogenesis of several thrombotic and non-thrombotic diseases. The effect of PAI-1 inhibition can be studied in mouse models, when appropriate immunological tools are available. The majority of the available monoclonal antibodies against PAI-1 have been raised against human PAI-1. Even though some of these antibodies cross-react with non-glycosylated PAI-1 from different species, these antibodies often do not cross-react sufficiently with glycosylated mouse PAI-1. Moreover, the antibodies that cross-react with glycosylated mouse PAI-1 often have decreased inhibitory properties in the presence of vitronectin. Our objective was the generation of a panel of monoclonal antibodies reacting with vitronectin-bound glycosylated mouse PAI-1.
Five monoclonal antibodies revealed binding to glycosylated mouse PAI-1 and exerted a strong (i.e., 58-80% inhibition of PAI-1 activity) inhibitory effect toward mouse PAI-1. Similar inhibitory effects were seen in the presence of a 33-fold molar excess of vitronectin. The PAI-1 inhibitory potential of the antibodies in vivo was demonstrated in a thromboembolism model, in which the evaluated antibodies significantly increased the percentage of mice with normal physical activity in comparison to mice treated with negative control antibody.
To the best of our knowledge this is the first panel of monoclonal antibodies that can inhibit mouse PAI-1 in the presence of vitronectin and that show a profibrinolytic effect in vivo. Therefore these antibodies provide excellent immunological tools to further investigate the role of PAI-1 in mouse models.
PAI-1 是 t-PA 和 u-PA 的主要生理抑制剂。PAI-1 水平升高与多种血栓性和非血栓性疾病的发病机制有关。当有适当的免疫工具可用时，可以在小鼠模型中研究 PAI-1 抑制的效果。大多数针对 PAI-1 的单克隆抗体都是针对人 PAI-1 产生的。尽管其中一些抗体与不同物种的非糖基化 PAI-1 发生交叉反应，但这些抗体通常与糖基化的小鼠 PAI-1 反应不足。此外，与糖基化的小鼠 PAI-1 发生交叉反应的抗体在存在 vitronectin 时抑制特性往往会降低。我们的目标是生成一组与 vitronectin 结合的糖基化小鼠 PAI-1 反应的单克隆抗体。
有 5 种单克隆抗体显示与糖基化的小鼠 PAI-1 结合，并对小鼠 PAI-1 产生强烈的抑制作用（即抑制 PAI-1 活性的 58%-80%）。在 vitronectin 存在 33 倍摩尔过量的情况下也观察到类似的抑制作用。在血栓栓塞模型中，体内抗体的 PAI-1 抑制潜力得到了证明，与用阴性对照抗体治疗的小鼠相比，评估的抗体显著增加了正常活动的小鼠百分比。
据我们所知，这是第一组能够在 vitronectin 存在的情况下抑制小鼠 PAI-1 并在体内显示出纤维蛋白溶解作用的单克隆抗体。因此，这些抗体为进一步研究 PAI-1 在小鼠模型中的作用提供了出色的免疫工具。
