CD1d/NKT-binding glycolipids in enhancing the immunogenicity of a malaria vaccine

描述（由申请人提供）：根除全球病原体，包括疟疾，取决于开发有效的疫苗。实现疫苗成功的关键策略之一是确定和开发一种基于新机制的佐剂。？-galactocylceramide (?-GalCer)是一种已被广泛研究的糖脂，已知通过结合CD1d分子和刺激免疫应答的重要亚群——不变性NKT （iNKT）细胞，显示出显著的生物活性，包括辅助作用。最近，我们发现了一本小说？-GalCer类似物，7DW8-5，在与候选疟疾疫苗联合肌内注射时，可强烈增强疟疾特异性保护性免疫反应水平。什么时候比较？-GalCer，它的亲本糖脂，我们发现7DW8-5的辅助作用明显更好。7DW8-5不仅对iNKT细胞和树突状细胞（dc）具有更强的刺激活性，而且与小鼠和人CD1d分子的结合亲和力比？-GalCer更高。令人惊讶的是，我们发现通过静脉注射，只有？- galcer，而不是7DW8-5，诱导了包括IFN-?在内的细胞因子的系统性产生。和IL-12，而两种糖脂在静脉给药后诱导相似水平的全身细胞因子产生。我们推测，由于7DW8-5与CD1d分子具有更高的结合亲和力和/或7DW8-5上调活化dc上CD1d的表达水平，7DW8-5保留在注射部位和引流淋巴结附近。因此，在Aim 1中，我们将首先确定7DW8-5是否确实在局部保留，如果是，如何阻止7DW8-5扩散并诱导全身细胞因子的产生。我们还怀疑其局部保留与7DW8-5发挥的优越佐剂作用直接相关，并假设7DW8-5诱导的DCs活化增加导致疫苗引发的适应性免疫反应更强。我们将在Aim 2中检验这一假设。最后，目前尚不清楚7DW8-5是否确实可以增强体液和CD4+ T细胞反应，以及这些反应是否有助于预防疟疾。因此，使用缺乏CD8+ T细胞和/或抗体的小鼠，我们将在Aim 3中确定这些问题。鉴于我们最近的研究表明，7DW8-5对一种基于腺病毒的非人类灵长类疟疾疫苗的细胞免疫原性具有显著的佐剂作用，并且由于7DW8-5将于2012年进入1期临床试验，因此拟议的研究对于7DW8-5不仅作为各种疫苗的佐剂，而且作为直接治疗剂的未来临床应用是必不可少的。

DESCRIPTION (provided by applicant): The eradication of global pathogens, including malaria, hinges upon the development of effective vaccines. One of the key strategies to realize successful vaccines is to identify and develop a new mechanism-based adjuvant. ?-galactocylceramide (?-GalCer), a glycolipid that has been extensively investigated, is known to display a significant biological activity, including an adjuvant effect, by binding CD1d molecules and stimulating invariant NKT (iNKT) cells, an important sub-population of the immune response. Recently, we identified a novel ?-GalCer analog, 7DW8-5, which can strongly enhance the level of malaria-specific protective immune response upon its intra-muscular (i.m.) co-administration with a candidate malaria vaccine. When compared to ?-GalCer, its parental glycolipid, we found the adjuvant effect of 7DW8-5 to be clearly superior. 7DW8-5 exhibited not only a stronger stimulatory activity towards iNKT cells and dendritic cells (DCs), but also a higher binding affinity to both mouse and human CD1d molecules than ?-GalCer. Very surprisingly, we discovered that when administered by i.m. injection, only ?-GalCer, but not 7DW8-5, induced a systemic production of cytokines including IFN-? and IL-12, whereas both glycolipids induced a similar level of systemic cytokine production upon their intravenous administration. We hypothesize that 7DW8-5 is retained locally at the i.m. injection site and nearby draining lymph nodes due its higher binding affinity to CD1d molecules and/or the up- regulation of CD1d expression level on activated DCs by 7DW8-5. In Aim 1, therefore, we will first determine whether 7DW8-5 is indeed retained locally and if so, how 7DW8-5 is prevented from spreading out and inducing systemic cytokine production. We also suspect that its local retention is directly related to the superior adjuvant effect exerted by 7DW8-5 and hypothesize that an increased activation of DCs induced by 7DW8-5 results in a stronger onset of the adaptive immune response elicited by vaccines. We will test this hypothesis in Aim 2. Finally, it is still unclear whether 7DW8-5 could indeed enhance humoral and CD4+ T cell responses and whether these responses could contribute to the protection against malaria. Therefore, using mice lacking CD8+ T cells and/or antibodies, we will determine these issues in Aim 3. In view of our recent studies showing that 7DW8-5 provides a significant adjuvant effect on the cellular immunogenicity of an adenovirus-based malaria vaccine in non-human primates, and because 7DW8-5 is advancing into a Phase 1 clinical trial in 2012, the proposed studies should be imperative for the future clinical applications of 7DW8-5 not only as an adjuvant for various vaccines, but also as a direct therapeutic agent. PUBLIC HEALTH RELEVANCE: Malaria continues to pose a grave threat to the global community and in particular to adults and children traveling to or living in tropical and subtropicl regions of the world. The purpose of this proposal is to study and understand how the efficacy of malaria vaccines gets enhanced by employing glycolipids as immuno- enhancing compounds or "adjuvants." The development of a suitable malaria vaccine/glycolipid adjuvant combination would have the potential to decrease the incidence of malaria and diminish the morbidity and mortality attributable to this pathogen.