The NLR-inflammasome as mediator of Alum's adjuvanticity

描述(申请人提供)：明矾是唯一被批准在人类疫苗接种中常规使用的佐剂，尽管其佐剂的基础仍然知之甚少。我们最近证实，明胶可激活caspase-1，并诱导分泌成熟的白介素12(IL-12)和IL-18。我们的初步结果还表明，Caspase-1的激活和明胶对IL-12分泌的刺激依赖于ASC蛋白，这是一种被几个节点样受体(NLR)使用的接头分子，这表明该家族的成员可能介导了明矾的免疫刺激作用。NLR是一种模式识别受体，识别位于细胞质中的微生物产物。几个NLR是称为炎症体的多蛋白复合体的一部分，该复合体还包含接头ASC和caspase-1，这是处理和分泌IL-12和IL-18所需的蛋白酶。大量研究证明了IL-12和IL-18的佐剂活性，特别是它们促进Th2分化的能力。明胶对Th1反应的诱导作用较差，但对Th2反应的支持作用较强，提示明矾的佐剂作用可能与其诱导IL-12和IL-18分泌的能力有关。IL-12和IL-18在明胶佐剂中的作用已被分析过，但结果相互矛盾或不确定。鉴于我们最近的结果，有必要重新审查这一问题。目前的拨款提案将从分子水平上阐明明胶的作用机制，具体目的如下：1.验证NLR家族成员通过明胶介导caspase-1激活和IL-12/IL-18分泌的假设：2.验证半胱氨酸天冬氨酸酶-1激活和IL-12/IL-18的释放介导明胶佐剂活性的假说。在工业化国家和发展中国家，疫苗接种仍然是抗击传染病的最有希望的战略。明矾是唯一被批准在人类疫苗接种中常规使用的佐剂，尽管其免疫刺激活性的基础仍然知之甚少。这项拨款提案中描述的研究将增加我们对明矾作用机制的了解。更深入地了解决定佐剂免疫刺激特性的机制是合理设计更复杂疫苗的先决条件。

DESCRIPTION (provided by applicant): Alum is the only adjuvant approved for routine use in human vaccination although the basis for its adjuvanticity remains poorly understood. We have recently demonstrated that Alum activates caspase-1 and induces secretion of mature Interleukin-12 (IL-12) and IL-18. Our preliminary results also show that caspase-1 activation and stimulation of IL-12 secretion by Alum is dependent on the protein ASC, an adaptor molecule used by several Nod-Like receptors (NLR), suggesting that members of this family may mediate Alum's immunostimulatory effects. NLR are pattern recognition receptors that recognize microbial products situated in the cytoplasm. Several NLR are part of a multiproteins complex called inflammasome that also contains the adaptor ASC and caspase-1, the protease required for processing and secretion of IL-12 and IL-18. Numerous studies documented the adjuvant activities of IL-12 and IL-18 and in particular their ability to encourage Th2 differentiation. Alum is notoriously a poor inducer of Th1 responses while it successfully sustains Th2 responses suggesting that Alum's adjuvanticity may be related to its ability to induce IL-12 and IL-18 secretion. The involvement of IL-12 and IL-18 in Alum adjuvanticity has been previously analyzed but with contradictory or inconclusive results. In light of our recent results a re-examination of this issue is needed. The present grant proposal will elucidate at the molecular level the mechanism of action of Alum by addressing the following specific aims: 1. Test the hypothesis that members of the NLR family mediate caspase-1 activation and IL-12/IL-18 secretion by Alum: 2. Test the hypothesis that caspase-1 activation and release of IL-12/IL-18 mediate the adjuvant activity of Alum. Vaccination remains the most promising strategy to fight infectious diseases in both industrialized and developing countries. Alum is the only adjuvant approved for routine use in human vaccination although the basis for its immunostimulatory activity remains poorly understood. The studies described in this grant proposal will increase our understanding of the mechanism of action of Alum. A deeper understanding of the mechanisms that determine the immunostimulatory properties of adjuvants is a prerequisite for the rational design of more sophisticated vaccines.