Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, UT 84112, USA.
Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
Biomaterials. 2018 Nov;182:92-103. doi: 10.1016/j.biomaterials.2018.08.008. Epub 2018 Aug 6.
Dendritic cell (DC)-based cytotoxic T lymphocyte (CTL) epitope vaccines are effective to induce CTL responses but require complex ex vivo DC preparation and epitope-loading. To take advantage of DC-based epitope vaccines without involving the ex vivo procedures, we aimed to develop carriers to directly load CTL epitopes onto DCs in vivo. Here, we first engineered a carrier consisting of a hydrophilic polypeptide, immune-tolerant elastin-like polypeptide (iTEP) and a substrate peptide of matrix metalloproteinases-9 (sMMP). The iTEP was able to solubilize CTL epitopes. CTL epitopes were connected to the carrier, iTEP-sMMP, through sMMP so that the epitopes can be cleaved from the carrier by MMP-9. iTEP-sMMP was found to release its epitope payloads in the DC culture media, which contained MMP-9 released from DCs. iTEP-sMMP allowed for the direct loading of CTL epitopes onto the surface MHC class I complexes of DCs. Importantly, iTEP-sMMP resulted in greater epitope presentation by DCs both in vitro and in vivo than a control carrier that cannot directly load epitopes. iTEP-sMMP also induced 2-fold stronger immune responses than the control carrier. To further enhance the direct epitope-loading strategy, we furnished iTEP-sMMP with an albumin-binding domain (ABD) and found the new carrier, ABD-iTEP-sMMP, had greater lymph node (LN) accumulation than iTEP-sMMP. ABD-iTEP-sMMP also resulted in greater immune responses than iTEP-sMMP by 1.5-fold. Importantly, ABD-iTEP-sMMP-delivered CTL epitope vaccine induced stronger immune responses than free CTL epitope vaccine. Taken together, these carriers utilized two physiological features of DCs to realize direct epitope-loading in vivo: the accumulation of DCs in LNs and MMP-9 released from DCs. These carriers are a potential substitute for DC-based CTL epitope vaccines.
树突状细胞（DC）基细胞毒性 T 淋巴细胞（CTL）表位疫苗可有效诱导 CTL 应答，但需要复杂的体外 DC 制备和表位加载。为了在不涉及体外程序的情况下利用基于 DC 的表位疫苗，我们旨在开发载体，以便将 CTL 表位直接加载到体内的 DC 上。在这里，我们首先设计了一种载体，该载体由亲水性多肽、免疫耐受弹性蛋白样多肽（iTEP）和基质金属蛋白酶-9（MMP-9）的底物肽组成。iTEP 能够溶解 CTL 表位。CTL 表位通过 MMP-9 连接到载体 iTEP-sMMP 上，以使表位可以从 MMP-9 从 DC 释放的载体上切割下来。发现 iTEP-sMMP 在含有从 DC 释放的 MMP-9 的 DC 培养基中释放其表位有效载荷。iTEP-sMMP 允许将 CTL 表位直接加载到 DC 表面 MHC Ⅰ类复合物上。重要的是，与不能直接加载表位的对照载体相比，iTEP-sMMP 在体外和体内都导致 DC 呈递更多的表位。iTEP-sMMP 还诱导了比对照载体强 2 倍的免疫应答。为了进一步增强直接表位加载策略，我们用白蛋白结合结构域（ABD）为 iTEP-sMMP 配备了一个白蛋白结合结构域（ABD），并发现新载体 ABD-iTEP-sMMP 在淋巴结（LN）中的积累比 iTEP-sMMP 多。ABD-iTEP-sMMP 还通过 1.5 倍使免疫应答大于 iTEP-sMMP。重要的是，ABD-iTEP-sMMP 递送的 CTL 表位疫苗比游离 CTL 表位疫苗诱导更强的免疫应答。总之，这些载体利用了 DC 的两个生理特征来实现体内的直接表位加载：DC 在 LN 中的积累和从 DC 释放的 MMP-9。这些载体是基于 DC 的 CTL 表位疫苗的潜在替代品。
