Activation of innate immune responses by a polyphosphazene adjuvant in pigs

佐剂是增强对疫苗的免疫反应的物质。到目前为止，佐剂已经用于数十亿剂动物疫苗。尽管它们被广泛使用，但人们对佐剂的工作原理知之甚少。这促使一位著名科学家说：“佐剂是免疫学家肮脏的小秘密”。对佐剂如何发挥作用缺乏详细了解，这是在疫苗中合理使用佐剂的障碍。此外，了解佐剂是如何发挥作用的，将减轻人们对其安全性的一些看法。*现有证据表明，大多数佐剂，如果不是所有佐剂，都是通过刺激天然免疫发挥作用的，而天然免疫反过来又指导抗原特异性免疫(获得性免疫)的发展。许多研究人员已经证明，佐剂影响先天免疫的各个方面，包括：某些化学介质(细胞因子和趋化因子)的产生，免疫细胞的募集和促进抗原向引流淋巴结的运输。**我们广泛发表了一种新型佐剂poly[di(sodiumcarboxylatoethylphenoxy)phosphazene](PCEP)的强大活性，它是一种合成的可生物降解的水溶性聚磷腈聚合物。我们已经证明，PCEP显著提高了对各种实验细菌和病毒疫苗的免疫反应。这些早期的研究大多是在小鼠身上进行的，但我们最近证明PCEP是一种很有前途的猪用佐剂，我们目前正在另外两个项目中探索PCEP在改进猪流感病毒(SIV)疫苗方面的潜力(见正在进行的研究支持)。然而，目前还没有关于PCEP在猪身上如何发挥作用的信息，这是合理使用它的障碍。由于大多数佐剂通过刺激天然免疫发挥作用，我们推断，研究PCEP如何激活天然免疫将提供关于这种佐剂如何在猪身上发挥作用的有价值的信息。在这方面，我们建议进行以下研究：1)评估PCEP在注射部位诱导的免疫反应基因的调节；2)调查PCEP对局部和全身细胞因子和趋化因子浓度的影响；3)识别在注射部位和引流淋巴结中招募的免疫细胞；4)研究PCEP在体外对免疫细胞的激活；以及5)评估是否需要在注射部位保留“抗原-佐剂复合体”(库形成)来实现PCEP的佐剂活性。**了解佐剂的工作原理将为合理使用和安全性提供有价值的信息。拟议工作的成果将是对这一目标的重大贡献。此外，拟议的研究将为动物疫苗中使用的其他佐剂进行类似的研究奠定基础。

Adjuvants are substances which enhance immune responses to vaccines. To date, adjuvants have been used in billions of doses of vaccines for animals. Despite their extensive use, very little is known about how adjuvants work. This prompted one famous scientist to state that "adjuvants are the immunologist's dirty little secret". The lack of detailed understanding of how adjuvants work is a barrier to their rational use in vaccines. Furthermore, knowing how adjuvants work would alleviate some of the perceptions regarding their safety. **Available evidence suggests that most adjuvants, if not all, act by stimulating innate immunity which in turn directs the development of antigen-specific immunity (adaptive immunity). Numerous investigators have demonstrated that adjuvants influence various aspects of innate immunity including; the production of certain chemical mediators (cytokines and chemokines), recruitment of immune cells and the promotion of antigen transport to draining lymph nodes. **We have published extensively on the strong activity of a novel adjuvant, poly[di(sodiumcarboxylatoethylphenoxy)phosphazene] (PCEP), which is a synthetic biodegradable and water-soluble polyphosphazene polymer. We have shown that PCEP dramatically increases immune responses to a variety of experimental bacterial and viral vaccines. Most of these earlier studies were done in mice, but we have recently demonstrated that PCEP is a promising adjuvant in pigs, and we are currently exploring the potential of PCEP in improving swine influenza virus (SIV) vaccines for pigs in two other projects (see ongoing research support). However, no information is available on how PCEP works in pigs, which is a barrier to its rational use. Since most adjuvants act by stimulating innate immunity, we reasoned that investigating how PCEP activates innate immunity will provide valuable information on how this adjuvant works in pigs. In this regard, we propose to perform the following studies; 1): Assess the regulation of immune response genes induced by PCEP at the injection site, 2) Investigate the effect of PCEP on local and systemic cytokine and chemokine concentrations, 3)Identify the immune cells recruited at the injection site and in the draining lymph node, 4) Investigate activation of immune cells by PCEP in vitro, and 5) Assess whether retention of "antigen-adjuvant complex" (depot formation) at the injection site is required for adjuvant activity of PCEP.**Understanding how adjuvants work will provide valuable information on their rational use and also on their safety. Results from the proposed work will be a significant contribution to this end. In addition, the proposed studies will lay groundwork for similar studies with other adjuvants used in animal vaccines.