Mechanisms of action of adjuvants in pigs

佐剂是增强对疫苗的免疫反应的物质。迄今为止，佐剂已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。一位著名的免疫学家曾经说过：“佐剂是免疫学家肮脏的小秘密”。对佐剂如何起作用缺乏详细的了解是其在疫苗中合理使用的障碍。此外，了解佐剂的工作原理将减轻人们对其安全性的一些看法。 有一个共识，大多数佐剂通过刺激先天免疫而起作用，这反过来又指导抗原特异性免疫的发展。有大量证据支持佐剂影响先天免疫的各个方面，包括：化学介质（细胞因子和趋化因子）的产生，免疫细胞的募集和抗原转运到引流淋巴结的促进。我们已经发表了大量关于新型佐剂PCEP的强活性的文章，PCEP是一种合成的可生物降解的聚磷腈聚合物。我们已经表明，PCEP显着增加对各种实验性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中进行的，但我们最近已经证明PCEP是一种有前途的猪佐剂。我们在其他项目中探索了PCEP在改进猪流感病毒疫苗方面的潜力。在我们过去几年的工作之前，没有关于PCEP如何在猪中起作用的信息。由于大多数佐剂通过刺激先天免疫起作用，因此我们推断，研究PCEP如何激活先天免疫将为这种佐剂如何在猪中起作用提供有价值的信息。在过去的几年中，我们已经从猪的体内研究中获得了证据，表明PCEP诱导免疫基因表达的改变，化学介质（细胞因子和趋化因子）的产生和细胞募集到注射部位。我们现在将在这些研究的基础上进一步阐明PCEP是如何通过继续体内研究来发挥作用的，并开始体外研究，以深入了解佐剂如何与靶细胞相互作用。我们建议进行以下研究：1）鉴定通过PCEP募集到注射部位的免疫细胞，2）确定抗原是否在疫苗中贡献佐剂活性，3）比较通过PCEP注射ID与IM注射募集的免疫细胞，4）确定储库的形成是否是PCEP的佐剂活性所需的，5）研究体外通过PCEP激活免疫细胞，6）研究PCEP诱导的猪细胞磷酸化信号转导。了解佐剂的工作原理将为合理使用及其安全性提供有价值的信息。拟议工作的成果将为此作出重大贡献。此外，拟议的研究将为动物疫苗中使用的其他佐剂的类似研究奠定基础。

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, little is known about how adjuvants work. A famous immunologist once stated 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 perceptions regarding their safety.  There is a consensus that most adjuvants act by stimulating innate immunity which in turn directs the development of antigen-specific immunity. There is plenty of evidence to support that adjuvants influence various aspects of innate immunity including; the production of 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 PCEP, which is a synthetic biodegradable 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. We have explored the potential of PCEP in improving swine influenza virus (SIV) vaccines for pigs in other projects. Prior to our work of the past few years, no information was available on how PCEP works in pigs. 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 the past several years we have obtained evidence from in vivo studies in pigs indicating that PCEP induces alterations in expression of immune genes, production of chemical mediators (cytokines and chemokines) and cell recruitment to the site of injection. We will now build on these studies to further elucidate how PCEP works by continuing in vivo studies and start on in vitro studies to provide insight into how the adjuvant interacts with the target cells. We propose the following studies; 1) Identify immune cells recruit to injection site by PCEP, 2) Determine whether antigen contributes adjuvant activity in a vaccine, 3) Compare immune cells recruited by PCEP injected ID versus IM injection, 4) Determine whether formation of a depot is required for adjuvant activity of PCEP, 5) Investigate activation of immune cells by PCEP in vitro, and 6) Study PCEP-induced phosphorylation signalling in porcine cells in vitro. 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.