Mol Pharm. 2020 Feb 3;17(2):507-516. doi: 10.1021/acs.molpharmaceut.9b00939. Epub 2019 Dec 30.
Targeted strategies to deliver and retain drugs to kidneys are needed to improve drug accumulation and efficacy in a myriad of kidney diseases. These drug delivery systems show potential for improving the therapeutic windows of drugs acting in the kidney. Biodistribution of antibody-based therapeutics in vivo is governed by several factors including binding affinity, size, and valency. Investigations of how the biophysical and biochemical properties of biologics enable them to overcome biological barriers and reach kidneys are therefore of interest. Although renal accumulation of antibody fragments in cancer diagnostics and treatment has been observed, reports on effective delivery of antibody fragments to the kidneys remain scarce. Previously, we demonstrated that targeting plasmalemma vesicle-associated protein (PV1), a caveolae-associated protein, can promote accumulation of antibodies in both the lungs and the kidneys. Here, by fine-tuning the binding affinity of an antibody toward PV1, we observe that the anti-PV1 antibody with reduced binding affinity lost the capability for kidney targeting while retaining the lung targeting activity, suggesting that binding affinity is a critical factor for kidney targeting of the anti-PV1 antibody. We next use the antibody fragment F(ab') targeting PV1 to assess the dual effects of rapid kidney filtration and PV1 targeting on kidney-selective targeting. Ex vivo fluorescence imaging results demonstrated that after rapidly accumulating in kidneys at 4 h, PV1-targeted F(ab') was continually retained in the kidney at 24 h, whereas the isotype control F(ab') underwent urinary elimination with significantly reduced signaling in the kidney. Confocal imaging studies confirmed the localization of PV1-targeted F(ab') in the kidney. In addition, the monovalent antibody fragment (Fab-C4) lost the capability for kidney homing, indicating that the binding avidity of anti-PV1 F(ab') is important for kidney targeting. Our findings suggest that PV1-targeted F(ab') might be useful as a drug carrier for renal targeting and highlight the importance of affinity optimization for tissue targeting antibodies.
需要针对肾脏的靶向药物递送和保留策略，以提高多种肾脏疾病中的药物积累和疗效。这些药物递送系统显示出改善在肾脏中起作用的药物治疗窗口的潜力。抗体类药物在体内的生物分布受多种因素影响，包括结合亲和力、大小和价态。因此，研究生物物理和生化特性如何使生物制剂能够克服生物屏障并到达肾脏是很有意义的。尽管已经观察到抗体片段在癌症诊断和治疗中的肾脏积累，但关于有效将抗体片段递送到肾脏的报道仍然很少。以前，我们证明了靶向质膜小泡相关蛋白（PV1），一种小窝相关蛋白，可以促进抗体在肺部和肾脏中的积累。在这里，通过微调抗体对 PV1 的结合亲和力，我们观察到结合亲和力降低的抗 PV1 抗体失去了肾脏靶向的能力，而保留了肺部靶向的活性，这表明结合亲和力是抗 PV1 抗体肾脏靶向的关键因素。接下来，我们使用靶向 PV1 的抗体片段 F(ab')来评估快速肾脏滤过和 PV1 靶向对肾脏选择性靶向的双重影响。离体荧光成像结果表明，在 4 小时内迅速在肾脏中积累后，靶向 PV1 的 F(ab')在 24 小时内持续保留在肾脏中，而同种型对照 F(ab')则通过尿液消除，肾脏中的信号显著减少。共聚焦成像研究证实了靶向 PV1 的 F(ab')在肾脏中的定位。此外，单价抗体片段（Fab-C4）失去了肾脏归巢的能力，表明抗 PV1 F(ab')的结合亲和力对于肾脏靶向很重要。我们的研究结果表明，靶向 PV1 的 F(ab')可能是一种用于肾脏靶向的药物载体，并强调了亲和力优化对于组织靶向抗体的重要性。
