Subcellular Mechanisms for Fungal Phagosome Maturation in Macrophages

描述(由申请人提供)：侵袭性真菌感染与高死亡率有关，通常超过90%，对免疫功能低下的患者造成不利影响，美国患者数量迅速增长。免疫调节疗法的出现和使用旨在治疗破坏性疾病，如自身免疫性炎症综合征(如类风湿性关节炎、克罗恩病、溃疡性结肠炎)，为患者提供了良好的疾病控制。实体和骨髓移植患者也受益于更强大的免疫抑制剂武器库，使更复杂的供受者器官匹配成为现实。不幸的是，这些生物和化疗药物没有特异性，会广泛抑制免疫，经常使患者容易受到严重的侵袭性真菌感染，包括念珠菌、曲霉菌和二相性生物，并代表着我们的医疗体系中日益增长的未得到满足的需求。真菌的清除过程始于天然免疫细胞对富含碳水化合物的真菌细胞壁的识别，随后是吞噬作用和吞噬溶酶体的形成。吞噬体成熟是一个动态的过程，是刺激持久适应性免疫的核心，但人们对此仍知之甚少。在这项申请中，候选人提议授予K08临床科学家指导研究职业发展奖，该奖项将解决真菌碳水化合物吞噬体成熟所需的一些关键的亚细胞分子机制及其对T细胞激活的影响。为了明确巨噬细胞的亚细胞机制，形成了一种由碳水化合物结合珠(FLP)组成的新型真菌样颗粒系统。用β-1，3-葡聚糖FLP分析纯化的巨噬细胞吞噬小体。数据表明，凝集素受体Dectin-1对β-1，3-葡聚糖FLP的表面识别控制着酸化和吞噬酶体的形成。候选人假设Dectin-1特定的信号将决定招募的吞噬体蛋白库的组成。具体地说，该提案旨在：1)确定Dectin-1信号在将Rab7b招募到真菌吞噬小体中的作用；2)描述NLRP3炎症体对吞噬小体成熟的贡献；3)确定Dectin-1信号在II类MHC抗原呈递和CD4+T细胞刺激中的作用。候选人已经完成了马萨诸塞州综合医院和布里格姆和妇女传染病项目的临床奖学金。作为他的博士论文工作的一部分，他在真菌免疫方面拥有研究经验，研究过抗隐球菌免疫，这与他提出的培训计划相吻合。这一职业发展资助概述了讲授和实用的板凳边研究培训，重点是真菌碳水化合物的免疫反应，提高了我们对宿主-真菌相互作用的理解，对于开发新的真菌疫苗策略至关重要，并为候选人提供必要的工具，以发展成为独立的生物医学研究员。

DESCRIPTION (provided by applicant): Invasive fungal infections are associated with high mortality rates often exceeding 90%, adversely affecting immunocompromised patients, a rapidly growing patient population in the United States. The advent and use of immune modulating therapeutics aimed at treating devastating diseases such as autoimmune inflammatory syndromes (e.g. rheumatoid arthritis, Crohn's, ulcerative colitis) has provided patients with excellent control of their disease. Solid and bone marrow transplant patients have also benefited from a more potent arsenal of immune suppressive agents making more complicated donor-recipient organ matches a real possibility. Unfortunately, these biologic and chemotherapeutic agents are not specific and act to suppress immunity broadly, often leaving patients susceptible to severe invasive fungal infections including Candida, Aspergillus and dimorphic organisms, and represents a growing unmet need in our healthcare system. The process of fungal elimination begins with innate immune cell recognition of the carbohydrate-rich fungal cell wall followed by phagocytosis and the formation of phagolysosomes. Phagosomal maturation is a dynamic process that is central to the stimulation of lasting adaptive immunity, yet remains poorly understood. In this application, the candidate proposes a K08 Mentored Clinical Scientist Research Career Development Award grant that will address some of the critical subcellular molecular mechanisms required for fungal carbohydrate phagosomal maturation and their influence on T cell activation. To define the subcellular mechanisms in macrophages, a novel fungal-like particle system composed of carbohydrate-conjugated beads (FLP) was formed. ¿-1,3-glucan FLP were used to analyze purified macrophage phagosomes. Data suggests that surface recognition of ¿ -1,3- glucan FLP by the lectin receptor, Dectin-1, controls acidification and phagolysosomal formation. The candidate hypothesizes that Dectin-1-specific signaling will dictate the composition of the recruited phagosomal protein repertoire. Specifically, the proposal aims will: 1) define the role Dectin-1 signaling in recruiting Rab7b to the fungal phagosome, 2) delineate the contribution of the NLRP3 inflammasome to phagosomal maturation, 3) determine the role of Dectin-1 signaling to class II MHC antigen presentation and CD4+ T cell stimulation. The candidate has completed a clinical fellowship in the combined Massachusetts General Hospital and Brigham and Women's Infectious Diseases Program. He has research experience in fungal immunity having studied anti-cryptococcal immunity, as part of his Ph.D. thesis work, which dovetails with his proposed training program. This career development grant outlines both didactic and practical bench- side research training focused on immune responses to fungal carbohydrates, improves our understanding of host-fungal interactions essential for the development of novel fungal vaccine strategies and provides the candidate with the necessary tools to develop into an independent biomedical investigator.