Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris Cité, F-75005 Paris, France.
Pharmaceutics Development Platform, Sanofi R&D, 94250 Gentilly, France.
Langmuir. 2022 May 10;38(18):5682-5691. doi: 10.1021/acs.langmuir.2c00269. Epub 2022 Apr 22.
Cell-penetrating peptides enter cells via diverse mechanisms, such as endocytosis, active transport, or direct translocation. For the design of orally delivered cell-penetrating peptides, it is crucial to know the contribution of these different mechanisms. In particular, the ability of a peptide to translocate through a lipid bilayer remains a key parameter for the delivery of cargos. However, existing approaches used to assess translocation often provide discrepant results probably because they have different sensitivities to the distinct translocation mechanisms. Here, we focus on the passive permeation of a range of hydrophobic cyclic peptides inspired by somatostatin, a somatotropin release-inhibiting factor. Using droplet interface bilayers (DIB), we assess the passive membrane permeability of these peptides and study the impact of the peptide cyclization and backbone methylation on translocation rates. Cyclization systematically improved the permeability of the tested peptides while methylation did not. By studying the interaction of the peptides with the DIB interfaces, we found membrane insertion and peptide intrinsic diffusion to be two independent factors of permeability. Compared to the industrial gold standard Caco-2 and parallel artificial membrane permeability assay (PAMPA) models, DIBs provide intermediate membrane permeability values, closer to Caco-2. Even for conditions where Caco-2 and PAMPA are discrepant, the DIB approach also gives results closer to Caco-2. Thereupon, DIBs represent a robust alternative to the PAMPA approach for predicting the permeability of peptides, even if the latter present extremely small structural differences.
细胞穿透肽通过多种机制进入细胞，如内吞作用、主动运输或直接转位。对于设计口服递送的细胞穿透肽，了解这些不同机制的贡献至关重要。特别是，肽穿过脂质双层的能力仍然是递送货物的关键参数。然而，用于评估转位的现有方法通常提供不一致的结果，可能是因为它们对不同的转位机制的敏感性不同。在这里，我们专注于一系列受生长抑素启发的疏水性环状肽的被动渗透，生长抑素是一种生长激素释放抑制因子。使用液滴界面双层 (DIB)，我们评估了这些肽的被动膜渗透性，并研究了肽环化和主链甲基化对转位速率的影响。环化系统地提高了测试肽的渗透性，而甲基化没有。通过研究肽与 DIB 界面的相互作用，我们发现膜插入和肽固有扩散是渗透性的两个独立因素。与工业黄金标准 Caco-2 和平行人工膜渗透性测定 (PAMPA) 模型相比，DIB 提供了更接近 Caco-2 的中间膜渗透性值。即使在 Caco-2 和 PAMPA 存在差异的情况下，DIB 方法也能更接近 Caco-2 得到结果。因此，DIB 代表了 PAMPA 方法的一种稳健替代方法，可用于预测肽的渗透性，即使后者具有极小的结构差异。
