Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, UT 84112, USA.
The First Affiliated Hospital and The Oncological Institute, Hainan Medical University, Haikou City, Hainan Province 570102, China.
Theranostics. 2018 Jan 1;8(1):223-236. doi: 10.7150/thno.21691. eCollection 2018.
Albumin-binding carriers have been shown to target cytotoxic T lymphocyte (CTL) vaccines to lymph nodes (LNs) and improve the efficacy of the vaccines. However, it was not clear whether the improved efficacy is solely due to the LN targeting, which prompted this study. First, we generated a fusion protein consisting of an albumin-binding domain (ABD) and an immune-tolerant elastin-like polypeptide (iTEP). Then, we examined the binding between this fusion protein, termed ABD-iTEP, and mouse serum albumin (MSA). Next, we evaluated the accumulation of ABD-iTEP in LNs and dendritic cells (DCs) in the LNs. We also analyzed antigen presentation and T cell activation of vaccines that were delivered by ABD-iTEP and investigated possible underlying mechanisms of the presentation and activation results. Last, we measured CTL responses induced by ABD-iTEP-delivered vaccines . ABD-iTEP bound with MSA strongly with an affinity of 1.41 nM. This albumin-binding carrier, ABD-iTEP, accumulated in LNs 3-fold more than iTEP, a control carrier that did not bind with albumin. ABD-iTEP also resulted in 4-fold more accumulation in DCs in the LNs than iTEP. Most importantly, ABD-iTEP drastically enhanced the antigen presentation of its vaccine payloads and the T cell activation induced by its payloads. The enhancement was dependent on the formation of the complex between MSA and ABD-iTEP. Meanwhile, the MSA/ABD-iTEP complex was found to have increased stability in acidic subcellular compartments and increased cytosolic accumulation in DCs, which might explain the enhanced vaccine presentation resulting from the complex. Finally, when ABD-iTEP was used to deliver CTL vaccines derived from both self- and non-self-antigens, it boosted the vaccine-induced responses by 2-fold in either case. ABD-iTEP not only targets vaccines to LNs but also promotes the presentation of the vaccines by DCs. Albumin-binding carriers have more than one mechanism to boost the efficacy of CTL vaccines.
白蛋白结合载体已被证明可将细胞毒性 T 淋巴细胞 (CTL) 疫苗靶向淋巴结 (LN)，并提高疫苗的疗效。然而，尚不清楚这种疗效的提高是否仅仅是由于 LN 靶向，这促使我们进行了这项研究。首先，我们生成了一种由白蛋白结合域 (ABD) 和免疫耐受弹性蛋白样多肽 (iTEP) 组成的融合蛋白。然后，我们检查了这种融合蛋白（称为 ABD-iTEP）与小鼠血清白蛋白 (MSA) 之间的结合。接下来，我们评估了 ABD-iTEP 在 LN 中的积累以及 LN 中的树突状细胞 (DC)。我们还分析了通过 ABD-iTEP 传递的疫苗的抗原呈递和 T 细胞激活，并研究了呈递和激活结果的潜在机制。最后，我们测量了 ABD-iTEP 传递的疫苗诱导的 CTL 反应。ABD-iTEP 与 MSA 强烈结合，亲和力为 1.41 nM。与不与白蛋白结合的对照载体 iTEP 相比，这种白蛋白结合载体 ABD-iTEP 在 LN 中的积累增加了 3 倍。ABD-iTEP 在 LN 中的 DC 中也积累了 4 倍以上。最重要的是，ABD-iTEP 大大增强了其疫苗有效载荷的抗原呈递和其有效载荷诱导的 T 细胞激活。这种增强依赖于 MSA 和 ABD-iTEP 之间形成的复合物。同时，发现 MSA/ABD-iTEP 复合物在酸性亚细胞区室中具有更高的稳定性，并在 DC 中增加了胞质内积累，这可能解释了复合物导致的疫苗呈递增强。最后，当 ABD-iTEP 用于递送源自自身和非自身抗原的 CTL 疫苗时，它在这两种情况下都将疫苗诱导的反应提高了 2 倍。ABD-iTEP 不仅将疫苗靶向 LN，还促进了 DC 中的疫苗呈递。白蛋白结合载体具有多种机制来提高 CTL 疫苗的疗效。
