Mechanisms of Immune Modulation Mediated by Yeast-derived Particulate Beta-Glucan

描述(申请人提供)：葡聚糖在补充和替代医学(CAM)中的使用在亚洲传统医学中盛行了几个世纪。然而，由于对它们的确切作用机制缺乏了解，它们在西医治疗恶性肿瘤的临床应用中取得了摇摆不定的成功。我们先前已经证明，低分子量的可溶性酵母葡聚糖能够与补体受体3(CR3，CD11b/CD18)的凝集素结合，并启动补体受体3(CR3，CD11b/CD18)的CR3+效应细胞对iC3b调理肿瘤细胞的细胞毒作用。研究结果表明，颗粒状酵母葡聚糖比可溶性葡聚糖具有更多独特的性质。本研究的目的是阐明颗粒状葡聚糖在肿瘤免疫治疗中的细胞和分子作用机制。 初步研究表明，颗粒葡聚糖而不是可溶性葡聚糖刺激巨噬细胞和树突状细胞(DC)激活和产生促炎细胞因子。此外，口服颗粒葡聚糖刺激DC，捕获凋亡的肿瘤细胞进行激活和成熟，导致增强的抗肿瘤CD4和CD8T细胞反应。值得注意的是，口服颗粒葡聚糖治疗改变了肿瘤微环境对Th1的反应。颗粒-葡聚糖也被证明通过另一种途径激活补体系统，导致C5a在肿瘤上沉积。这些初步数据为当前的研究提供了有力的基础。 目的1将剖析哪个信号通路(S)可能在颗粒-葡聚糖介导的DC激活和细胞因子释放中起关键作用。Toll样受体途径myd-88和TRIF缺陷小鼠，CR3缺陷小鼠，以及Dectin-1途径Dectin-1和CARD9缺陷小鼠将被用来解决这个问题。此外，还将在体外和体内检测在颗粒酵母刺激的DC存在下的T细胞分化(Th1、Th2和Th17)。目的2验证颗粒葡聚糖调节存在于肿瘤微环境中的抑制性细胞从而促进Th1反应的假设。将检测髓系抑制细胞(MDSCs)的功能，调节性T细胞(Treg)和Th17细胞之间的动态相互作用，MDSCs和肿瘤浸润性巨噬细胞之间的相互作用。我们将使用转导替代抗原卵蛋白和肿瘤相关抗原MUC1的Lewis肺癌作为模型系统来解决这些问题。目的3将验证颗粒葡聚糖刺激的补体激活可能部分有助于增强抗肿瘤T细胞反应的假设。此外，还将确定C3a和/或C5a及其受体C3aR和C5aR作为抗肿瘤T细胞反应调节剂的需求。进一步了解颗粒状葡聚糖的这些作用机制将对设计有效的临床应用具有重要价值。 公共卫生相关性：这项研究将阐明颗粒状酵母葡聚糖在肿瘤免疫治疗中的细胞和分子作用机制。这项研究中产生的数据将允许合理设计可用于临床试验的免疫治疗方案。

DESCRIPTION (provided by applicant): The use of ¿-glucans in complementary and alternative medicine (CAM) has prevailed for centuries in traditional Asian medicine. However, their clinical use against malignancies in Western medicine has experienced an oscillating success due to a lack of understanding in their exact mechanisms of action. We have previously demonstrated that soluble yeast ¿-glucan of low molecular weight is capable of binding to the lectin site of complement receptor 3 (CR3, CD11b/CD18) and priming CR3+ effector cells for cytotoxicity of iC3b-opsonized tumor cells. The work presented here shows that particulate yeast ¿-glucan has more unique features than soluble ¿-glucan. The objective of the proposed study is to elucidate the cellular and molecular mechanisms of action for particulate ¿-glucan in tumor immunotherapy. Preliminary studies demonstrated that particulate ¿-glucan, not soluble ¿-glucan, stimulated macrophages and dendritic cells (DCs) for activation and proinflammatory cytokine production. Furthermore, orally administered particulate ¿-glucan stimulated DCs that captured apoptotic tumor cells for activation and maturation, leading to the enhanced anti-tumor CD4 and CD8 T cell responses. Strikingly, oral particulate ¿-glucan treatment altered the tumor microenvironment toward Th1 response. Particulate ¿-glucan was also shown to activate the complement system via an alternative pathway, leading to C5a deposition on tumors. These preliminary data provide a strong basis for the current study. Aim 1 will dissect which signaling pathway(s) may be critical for particulate ¿-glucan-mediated DC activation and cytokine release. Toll-like receptor pathway MyD-88- and TRIF-deficient mice, CR3-deficient mice, and dectin-1 pathway dectin-1- and CARD9-deficient mice will be used to address this issue. In addition, T cell differentiation (Th1, Th2, and Th17) in the presence of particulate yeast ¿-glucan stimulated DCs will be examined both in vitro and in vivo. Aim 2 will test the hypothesis that particulate ¿-glucan modulates suppressive cells existing in the tumor microenvironment thereby promoting Th1 response. The function of myeloid-derived suppressive cells (MDSCs), dynamic interaction between regulatory T cells (Treg) and Th17 cells, cross-talk between MDSCs and tumor-infiltrating macrophages will be examined. Lewis lung carcinoma transfected with surrogate antigen ovalbumin and tumor-associated antigen MUC1 will be used as the model systems to address those issues. Aim 3 will test the hypothesis that particulate ¿-glucan stimulated complement activation may be partially contributed to the enhanced anti-tumor T cell responses. Furthermore, the requirement for C3a and/or C5a and their receptors, C3aR and C5aR, as modulators of anti-tumor T cell responses will be determined. Further knowledge of the mechanisms involved in these effects of particulate ¿-glucan will be of great value in the design of effective clinical applications. Public Health Relevance: This study will elucidate the cellular and molecular mechanisms of action of particulate yeast ¿-glucan in tumor immunotherapy. The data generated in this study will allow for the rational design of immunotherapeutic protocols usable in clinical trials.