Tatematsu Kenji, Iijima Masumi, Yoshimoto Nobuo, Nakai Tadashi, Okajima Toshihide, Kuroda Shun'ichi
The Institute of Scientific and Industrial Research, Osaka University, Ibaraki 567-0047, Japan.
The Institute of Scientific and Industrial Research, Osaka University, Ibaraki 567-0047, Japan.
Acta Biomater. 2016 Apr 15;35:238-47. doi: 10.1016/j.actbio.2016.02.010. Epub 2016 Feb 10.
The bio-nanocapsule (BNC) is an approximately 30-nm particle comprising the hepatitis B virus (HBV) envelope L protein and a lipid bilayer. The L protein harbors the HBV-derived infection machinery; therefore, BNC can encapsulate payloads such as drugs, nucleic acids, and proteins and deliver them into human hepatocytes specifically in vitro and in vivo. To diversify the possible functions of BNC, we generated ZZ-BNC by replacing the domain indispensable for the human hepatotrophic property of BNC (N-terminal region of L protein) with the tandem form of the IgG Fc-binding Z domain of Staphylococcus aureus protein A. Thus, the ZZ-BNC is an active targeting-based drug delivery system (DDS) nanocarrier that depends on the specificity of the IgGs displayed. However, the Z domain limits the animal species and subtypes of IgGs that can be displayed on ZZ-BNC. In this study, we introduced into BNC an Ig κ light chain-binding B1 domain of Finegoldia magna protein L (protein-L B1 domain) and an Ig Fc-binding C2 domain of Streptococcus species protein G (protein-G C2 domain) to produce LG-BNC. The LL-BNC was constructed in a similar way using a tandem form of the protein-L B1 domain. Both LG-BNC and LL-BNC could display rat IgGs, mouse IgG1, human IgG3, and human IgM, all of which not binding to ZZ-BNC, and accumulate in target cells in an antibody specificity-dependent manner. Thus, these BNCs could display a broad spectrum of Igs, significantly improving the prospects for BNCs as active targeting-based DDS nanocarriers.
We previously reported that ZZ-BNC, bio-nanocapsule deploying the IgG-binding Z domain of protein A, could display cell-specific antibody in an oriented immobilization manner, and act as an active targeting-based DDS nanocarrier. Since the Z domain can only bind to limited types of Igs, we generated BNCs deploying other Ig-binding domains: LL-BNC harboring the tandem form of Ig-binding domain of protein L, and LG-BNC harboring the Ig binding domains of protein L and protein G sequentially. Both BNCs could display a broader spectrum of Igs than does the ZZ-BNC. When these BNCs displayed anti-CD11c IgG or anti-EGFR IgG, both of which cannot bind to Z domain, they could bind to and then enter their respective target cells.
生物纳米胶囊（BNC）是一种约30纳米的颗粒，由乙型肝炎病毒（HBV）包膜L蛋白和脂质双层组成。L蛋白携带源自HBV的感染机制；因此，BNC可以包裹药物、核酸和蛋白质等有效载荷，并在体外和体内将它们特异性地递送至人肝细胞。为了使BNC的可能功能多样化，我们通过用金黄色葡萄球菌蛋白A的IgG Fc结合Z结构域的串联形式替换BNC的人肝营养特性所必需的结构域（L蛋白的N端区域）来生成ZZ-BNC。因此，ZZ-BNC是一种基于主动靶向的药物递送系统（DDS）纳米载体，其依赖于所展示IgG的特异性。然而，Z结构域限制了可以展示在ZZ-BNC上的IgG的动物种类和亚型。在本研究中，我们将巨大芬戈尔德菌蛋白L的Igκ轻链结合B1结构域（蛋白-L B1结构域）和链球菌属蛋白G的Ig Fc结合C2结构域（蛋白-G C2结构域）引入BNC以产生LG-BNC。LL-BNC以类似的方式使用蛋白-L B1结构域的串联形式构建。LG-BNC和LL-BNC都可以展示大鼠IgG、小鼠IgG1、人IgG3和人IgM，所有这些都不与ZZ-BNC结合，并以抗体特异性依赖的方式在靶细胞中积累。因此，这些BNC可以展示广泛的IgG，显著改善了BNC作为基于主动靶向的DDS纳米载体的前景。
我们之前报道过，部署蛋白A的IgG结合Z结构域的生物纳米胶囊ZZ-BNC可以以定向固定的方式展示细胞特异性抗体，并作为基于主动靶向的DDS纳米载体。由于Z结构域只能结合有限类型的IgG，我们生成了部署其他Ig结合结构域的BNC：携带蛋白L的Ig结合结构域串联形式的LL-BNC，以及依次携带蛋白L和蛋白G的Ig结合结构域的LG-BNC。与ZZ-BNC相比，这两种BNC都可以展示更广泛的IgG。当这些BNC展示抗CD11c IgG或抗EGFR IgG时，这两种抗体都不能与Z结构域结合，它们可以结合并随后进入各自的靶细胞。
