Christensen Sarah Christine, Hudecz Diána, Jensen Allan, Christensen Søren, Nielsen Morten Schallburg
Department of Biomedicine, Aarhus University, Høegh-Guldbergsgade 10, Building 1116, 8000, Aarhus C, Denmark.
Department of Biotherapeutic Discovery, H. Lundbeck A/S, Copenhagen, Denmark.
Mol Neurobiol. 2021 Sep;58(9):4392-4403. doi: 10.1007/s12035-021-02421-x. Epub 2021 May 20.
The blood-brain barrier (BBB) poses challenges for delivering antibody-based therapeutics to the brain and is a main obstacle for the successful application of biotherapeutics for the treatment of brain disorders. As only a small fraction of monoclonal antibodies (mAbs) is penetrating the BBB, high doses of therapeutics are required to elicit a pharmacological effect. This limitation has evoked research to improve transport across the BBB through receptor-mediated transcytosis, and several receptors have been explored for mediating this process. A recently suggested candidate is the brain endothelial cells (BECs) expressed basigin. Here, we explore the transcytosis capacity of different basigin mAbs targeting distinct epitopes using the porcine in vitro BBB models and provide data showing the intracellular vesicle sorting of these basigin mAbs in porcine BECs. Our data suggest that basigin mAbs avoid the lysosomal degradation pathway and are internalized to vesicles used by recycling receptors. Engagement of basigin mAbs with basigin led to the translocation of the mAbs across the tight BECs into the astrocytes in our in vitro BBB co-culture model. Although mAbs with higher binding affinity to basigin showed a greater astrocyte internalization, based on our experiments, it is not clear whether the transcytosis is affinity- or epitope-dependent or a combination of both. Overall, this study provides information about the intra- and intercellular fate of basigin mAbs in BECs, which are valuable for the future design of basigin-mediated drug delivery platforms.
血脑屏障（BBB）给将基于抗体的治疗药物递送至大脑带来了挑战，并且是生物治疗药物成功应用于脑部疾病治疗的主要障碍。由于只有一小部分单克隆抗体（mAb）能够穿透血脑屏障，因此需要高剂量的治疗药物才能产生药理作用。这一限制引发了通过受体介导的转胞吞作用来改善血脑屏障转运的研究，并且已经探索了几种受体来介导这一过程。最近提出的一个候选受体是脑内皮细胞（BEC）表达的基底膜蛋白。在此，我们使用猪体外血脑屏障模型探索了靶向不同表位的不同基底膜蛋白单克隆抗体的转胞吞能力，并提供了数据表明这些基底膜蛋白单克隆抗体在猪脑内皮细胞中的细胞内囊泡分选情况。我们的数据表明，基底膜蛋白单克隆抗体避免了溶酶体降解途径，并被内化到回收受体使用的囊泡中。在我们的体外血脑屏障共培养模型中，基底膜蛋白单克隆抗体与基底膜蛋白的结合导致单克隆抗体穿过紧密连接的脑内皮细胞转运到星形胶质细胞中。尽管与基底膜蛋白具有更高结合亲和力的单克隆抗体显示出更大的星形胶质细胞内化，但根据我们的实验，尚不清楚转胞吞作用是亲和力依赖性还是表位依赖性，亦或是两者的结合。总体而言，本研究提供了有关基底膜蛋白单克隆抗体在脑内皮细胞内和细胞间命运的信息，这对于未来设计基底膜蛋白介导的药物递送平台具有重要价值。
