Adjuvants' mechanisms

描述（由申请人提供）：基于蛋白质的受体配体相互作用被普遍认为是免疫激活的起始点。然而，它是否适用于实体结构的免疫识别是值得怀疑的。这个问题与疫苗设计特别相关，因为一些最著名的佐剂是固体晶体，如明矾和尿酸钠。抗原呈递细胞（APC）结合颗粒抗原是免疫激活的关键步骤。已经证明尿酸和明矾晶体是有效的佐剂，启动一个强大的适应性免疫反应。然而，其激活机制尚不清楚。使用原子力显微镜作为实时单细胞激活分析的工具，我们已经收集到尿酸和明矾晶体可以直接与细胞膜接触的证据，其力比基于蛋白质的细胞接触强得多。颗粒物质的结合激活树突状细胞中Syk激酶依赖的信号传导。这些观察结果提示了一种机制，即免疫细胞激活可以通过膜脂改变由固体结构触发，而不需要特定的细胞表面受体，以及晶体相关炎症和佐剂的可测试假设。在本提案中，我们扩展了研究结果，以研究所涉及的信号机制，特别是细胞表面脂质分选和下游信号转导之间的关联，晶体介导的免疫激活的关键步骤，以及该机制如何影响抗原递呈。这项工作的结果将影响疫苗的开发和我们对晶体相关疾病的理解。

DESCRIPTION (provided by applicant): Protein based receptor ligand interactions are universally regarded as the initiating point of immune activation. However, it is questionable if i is applicable to immune recognition of solid structures. This issue is particularly relevant in vaccine design as some of the best known adjuvants are solid crystals, such as alum and monosodium urate. Binding of particulate antigens by antigen presenting cells (APC) is a critical step in immune activation. It has been demonstrated that uric acid and alum crystals are potent adjuvants, initiating a robust adaptive immune response. However, the mechanisms of activation are unknown. Using atomic force microscopy as a tool for real time single cell activation analysis, we have collected evidence that uric acid and alum crystals can directly engage cellular membranes, with a force substantially stronger than protein based cellular contacts. Binding of particulate substances activates Syk kinase-dependent signaling in dendritic cells (DCs). These observations suggest a mechanism whereby immune cell activation can be triggered by solid structures via membrane lipid alteration without the requirement for specific cell surface receptors, and a testable hypothesis for crystal-associated inflammation and adjuvanticity. In this proposal, we extend the findings to study the signaling mechanisms involved, particularly the association between cell surface lipid sorting and downstream signal transduction, critical steps in crystal mediated immune activation, as well as how this mechanism affects antigen presentation. The outcome of this work will impact vaccine development and our understanding of crystal related diseases.