Mechanisms of action of adjuvants 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，但人们对佐剂是如何工作的知之甚少。一位著名的免疫学家曾说过：“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。*有一种共识，即大多数佐剂通过刺激天然免疫来发挥作用，天然免疫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，免疫细胞的募集和促进抗原向引流淋巴结的运输。我们已经广泛发表了一种新型助剂PCEP的强大活性，这是一种合成的可生物降解的聚磷腈聚合物。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，但我们最近证明了PCEP是一种很有前途的猪佐剂。我们已经在其他项目中探索了PCEP在改进猪流感病毒(SIV)疫苗方面的潜力。在我们过去几年的工作之前，没有关于PCEP如何在猪身上发挥作用的信息。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。在过去的几年里，我们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)的产生以及细胞在注射部位的募集。我们现在将在这些研究的基础上，通过继续体内研究来进一步阐明PCEP的工作原理，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PCEP招募到注射部位的免疫细胞，2)确定抗原是否有助于疫苗的佐剂活性，3)比较PCEP注射ID和IM招募的免疫细胞，4)确定PCEP佐剂活性是否需要形成一个库，5)体外研究PCEP对免疫细胞的激活，6)体外研究PCEP诱导的猪细胞磷酸化信号转导。了解佐剂是如何起作用的，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, 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.