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

描述（由申请人提供）：在补充和替代医学（CAM）中使用葡聚糖在传统的亚洲医学中已经流行了几个世纪。然而，由于缺乏对其确切作用机制的了解，它们在西医中对恶性肿瘤的临床应用经历了摇摆不定的成功。我们之前已经证明，低分子量可溶性酵母葡聚糖能够结合补体受体3（CR 3，CD 11b/CD 18）的凝集素位点，并引发CR 3+效应细胞对iC 3b调理的肿瘤细胞的细胞毒性。本文介绍的工作表明，颗粒状酵母葡聚糖比可溶性葡聚糖具有更多独特的特性。本研究的目的是阐明颗粒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，颗粒状的葡聚糖（而非可溶性葡聚糖）可刺激巨噬细胞和树突细胞（DC）的活化和促炎细胞因子的产生。此外，口服颗粒葡聚糖刺激DC，捕获凋亡肿瘤细胞进行活化和成熟，导致抗肿瘤CD 4和CD 8 T细胞应答增强。引人注目的是，口服颗粒葡聚糖治疗改变了肿瘤微环境对Th 1的反应。颗粒状的葡聚糖也被证明通过替代途径激活补体系统，导致C5 a沉积在肿瘤上。这些初步数据为目前的研究提供了坚实的基础。 目的1将剖析哪些信号通路可能对颗粒葡聚糖介导的DC活化和细胞因子释放至关重要。Toll样受体途径MyD-88和TRIF缺陷小鼠、CR 3缺陷小鼠和dectin-1途径dectin-1和CARD 9缺陷小鼠将用于解决该问题。此外，将在体外和体内检查颗粒酵母葡聚糖刺激的DC存在下的T细胞分化（Th 1、Th 2和Th 17）。目标2将检验颗粒葡聚糖调节肿瘤微环境中存在的抑制性细胞从而促进Th 1应答的假设。将检查骨髓源性抑制细胞（MDSC）的功能、调节性T细胞（Treg）和Th 17细胞之间的动态相互作用、MDSC和肿瘤浸润巨噬细胞之间的串扰。用替代抗原卵清蛋白和肿瘤相关抗原MUC 1转染的刘易斯肺癌将被用作解决这些问题的模型系统。目标3将检验颗粒葡聚糖刺激补体激活可能部分有助于增强抗肿瘤T细胞应答的假设。此外，将确定对C3 a和/或C5 a及其受体C3 aR和C5 aR作为抗肿瘤T细胞应答的调节剂的需求。进一步了解颗粒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：本研究将阐明颗粒酵母葡聚糖在肿瘤免疫治疗中的细胞和分子作用机制。本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.