Dong Shuyun, Subramanian Sundharraman, Parent Kristin N, Chen Mingnan
Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, UT 84112, USA.
Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.
J Control Release. 2020 Dec 10;328:653-664. doi: 10.1016/j.jconrel.2020.09.033. Epub 2020 Sep 19.
Vaccines that induce cytotoxic T lymphocyte (CTL)-mediated immune responses constitute an important class of medical tools to fend off diseases like infections and malignancy. Epitope peptides, as a format of CTL vaccines, are being tested preclinically and clinically. To elicit CTL responses, epitope vaccines go through an epitope presentation pathway in dendritic cells (DCs) that has multiple bottleneck steps and hence is inefficient. Here, we report the development of a strategy to overcome one of these barriers, phagolysosomal escape in DCs. First, we furnished a previously established carrier-an immune-tolerant elastin-like polypeptide nanoparticle (iTEP NP)-with the peptides that are derived from the DNA polymerase of herpes simplex virus 1 (Pol peptides). Pol peptides were reported to facilitate phagolysosomal escape. In this study, while we found that Pol peptides promoted the CTL epitope presentation; we also discovered Pol peptides disrupted the formation of the iTEP NP. Thus, we engineered a series of new iTEPs and identified several iTEPs that could accommodate Pol peptides and maintain their NP structure at the same time. We next optimized one of these NPs so that its stability is responsive to its redox environment. This environment-responsive NP further strengthened the CTL epitope presentation and CTL responses. Lastly, we revealed how this NP and Pol peptides utilized biological cues of phagolysosomes to realize phagolysosomal escape and epitope release. In summary, we developed iTEP NP carriers with a new phagolysosomal escape function. These carriers, with their priorly incorporated functions, resolve three bottleneck issues in the CTL epitope presentation pathway: vaccine uptake, phagolysosomal escape, and epitope release.
诱导细胞毒性T淋巴细胞（CTL）介导的免疫反应的疫苗是抵御感染和恶性肿瘤等疾病的一类重要医疗工具。表位肽作为CTL疫苗的一种形式，正在进行临床前和临床测试。为了引发CTL反应，表位疫苗在树突状细胞（DC）中经历表位呈递途径，该途径有多个瓶颈步骤，因此效率低下。在此，我们报告了一种克服这些障碍之一——DC中吞噬溶酶体逃逸的策略的开发。首先，我们为先前建立的载体——一种免疫耐受的弹性蛋白样多肽纳米颗粒（iTEP NP）——配备了源自单纯疱疹病毒1型DNA聚合酶的肽（Pol肽）。据报道，Pol肽有助于吞噬溶酶体逃逸。在本研究中，我们发现Pol肽促进了CTL表位呈递；同时我们也发现Pol肽破坏了iTEP NP的形成。因此，我们设计了一系列新的iTEP，并鉴定出几种能够容纳Pol肽并同时保持其NP结构的iTEP。接下来，我们优化了其中一种NP，使其稳定性对其氧化还原环境有响应。这种环境响应性NP进一步增强了CTL表位呈递和CTL反应。最后，我们揭示了这种NP和Pol肽如何利用吞噬溶酶体的生物学线索来实现吞噬溶酶体逃逸和表位释放。总之，我们开发了具有新的吞噬溶酶体逃逸功能的iTEP NP载体。这些载体凭借其先前整合的功能，解决了CTL表位呈递途径中的三个瓶颈问题：疫苗摄取、吞噬、吞噬溶酶体逃逸和表位释放。
