Regulation of Innate Immune System Sensing of C. albicans Infection

天然免疫系统对白色念珠菌感染感知的调节

• 批准号: 9262609
• 负责人: JIAN ZHANG
• 金额: $ 1.32万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9262609
• 关键词: Adverse effects; Antifungal Agents; Binding; Bone Marrow; C Type Lectin Receptors; CBLB gene; Candida; Candida albicans; Candidiasis; Cell Wall; Cell surface; Cells; Clinical; Data; Development; Diagnostic; Disseminated candidiasis; Dose; Drug resistance; Enzymes; Family; Family member; Homeostasis; Hospitals; Host Defense; Host Defense Mechanism; Hyphae; Immune; Immune system; Immunity; Immunocompetent; Immunocompromised Host; Impairment; In Vitro; Infection; Infectious Skin Diseases; Inflammatory; Inflammatory Response; Innate Immune Response; Innate Immune System; Lead; Life; LoxP-flanked allele; Lymphoma; Lysine; Mannans; Mediating; Molecular; Morbidity - disease rate; Mucous Membrane; Mus; Mutation; Mycoses; Patients; Pattern recognition receptor; Pharmaceutical Preparations; Phenotype; Play; Polyubiquitination; Preventive; Proteins; Recruitment Activity; Recycling; Regulation; Role; Sepsis; Signal Transduction; Site; Small Interfering RNA; Surface; T-Cell Activation; TLR2 gene; Testing; Therapeutic; Tyrosine Phosphorylation; Ubiquitination; Vagina; Wild Type Mouse; Yeasts; base; beta-Glucans; candidate identification; candidemia; cell type; combat; cytokine; dectin 1; fungus; immune resistance; in vivo; insight; macrophage; member; mortality; mouse dectin-2; oral infection; pathogen; protein B; public health relevance; response; therapeutic target; tool; ubiquitin ligase; ubiquitin-protein ligase

 DESCRIPTION (provided by applicant): Disseminated C. albicans infection in patients who have a weakened immune system is life-threatening. In hospitals 40% of bloodstream infections (candidemia) are caused by Candida spp. Despite the availability of several anti-fungal drugs, invasive candidiasis still has a high mortality rate ranging from 45 to 75%. The high morbidity and mortality associated with disseminated candidiasis are mainly due to the lack of early and accurate diagnostic tools, the limited anti-fungal drugs, and the emergence of drug resistance, thus highlighting the need to further understand host-pathogen interactions and the mechanisms of immune resistance to fungal spread, and to develop alternative immune-based strategies to combat candidemia. In normal hosts, C. albicans is controlled after activation of innate immune cells via cell surface pattern recognition receptors (PRRs) such as TLR2 and C-type lectin receptors (CLRs) that detect the infecting fungi. The CLRs Dectin-1 and Dectin-2/3 recognize C. albicans yeast cells and hyphae by binding to the surface β-glucans and α- mannans of the two fungal forms, respectively. Recognition of these molecules results in release of inflammatory cytokines from innate immune cells, which is critical for anti-fungal immunity. The mechanisms that control this CLR-mediated innate immune response to fungal infection are completely unknown. Our preliminary results showed that bone marrow-derived macrophages (BMDMs) from Cblb-/- mice infected with C. albicans yeast and hyphae produce more inflammatory cytokines than do BMDMs from wild type (WT) mice. This response involves signaling via Dectin-1, -2, and/or -3 but not via the TLRs. This finding suggests that Cbl-b acts through the Dectin CLRs but not the TLRs in macrophages. Consistent with this notion, BMDMs from Cblb-/- mice have impaired Dectin-1, -2, and -3 degradation upon interaction with C. albicans yeast and hyphae. In support of this finding, Dectin-1 undergoes poly-ubiquitination in macrophages upon infection with C. albicans yeasts, whereas this ubiquitination is abrogated in BMDMs lacking Cbl-b. Furthermore, Cblb-/- mice are protected from infection with a lethal dose of C. albicans. Based on these results, we hypothesize that during C. albicans infection, Cbl-b is recruited to Dectin CLRs, and this targets Dectins for ubiquitination which dampens CLR-mediated innate immune responses against fungi. To test this hypothesis, we propose to determine (1) whether and how Cbl-b regulates Dectin down-modulation via protein ubiquitination in vitro; and (2) whether Cbl-b dampens host effective responses against C. albicans mediated by the Dectin family of CLRs. Successful completion of this project will reveal a previously unknown host defense mechanism and provide molecular insight into the host defense machinery and ultimately facilitate the identification of candidate targets for appropriate modulation of anti-fungal responses and therapeutic options.

 描述（适用提供）：免疫系统弱化的患者中散布白色念珠菌感染正在威胁生命。在医院中，有40％的血液感染（念珠菌血症）是由念珠菌属引起的。尽管有几种抗真菌药物的可用性，但侵入性念珠菌病的死亡率仍为45％至75％。与传播的念珠菌病有关的高发病和死亡率主要是由于缺乏早期，准确的诊断工具，有限的抗真菌药物以及耐药性的出现，因此强调需要进一步理解宿主 - 病原体相互作用，以及对真实性免疫传播的免疫能力的机制，以及为真实性免疫差异而开发替代免疫策略，以及对替代策略进行替代的策略性综合型鉴定型鉴别。在正常宿主中，白色念珠菌在通过细胞表面模式识别受体（PRR）（例如TLR2和C型凝集素受体（CLR）（CLR）激活后，对白色念珠菌进行控制，这些受体检测到感染的真菌。 CLR Dectin-1和Dectin-2/3分别与两种真菌形式的表面β-葡聚糖和α-甘露群结合，识别白色念珠菌酵母细胞和菌丝。这些分子的识别导致先天免疫细胞释放炎性细胞因子，这对于抗真菌免疫至关重要。控制这种CLR介导的对真菌感染的先天免疫反应的机制是完全未知的。我们的初步结果表明，与野生型（WT）小鼠的BMDM相比，感染了白色念珠菌酵母和菌丝感染的CBLB - / - 小鼠的骨髓衍生的巨噬细胞（BMDM）。该响应涉及通过dectin -1，-2和/或-3信号传导，但不通过TLRS进行信号传导。这一发现表明，CBL-B通过dectin CLR作用，而不是巨噬细胞中的TLR。与此概念一致，与白色念珠菌酵母和菌丝相互作用后，来自CBLB - / - 小鼠的BMDM会损害dectin-1，-2和-3降解。为了支持这一发现，Dectin-1在用白色念珠菌酵母菌感染后在巨噬细胞中经历多泛素化，而这种泛素化在缺乏CBL-B的BMDM中被废除。此外，CBLB - / - 小鼠免受致命剂量C.白色念珠菌的感染。基于这些结果，我们假设在白色念珠菌感染期间，将CBL-B募集到dectin clrs中，这将靶向泛素化素，从而抑制CLR介导的对真菌的先天免疫反应。为了检验这一假设，我们建议确定（1）CBL-B是否在体外蛋白质泛素化来调节dectin降低调节； （2）CBL-B DAMM是否对CLR的Dectin家族介导的白色念珠菌有效反应。该项目的成功完成将揭示以前未知的宿主防御机制，并为宿主防御机制提供分子见解，并最终支持识别候选目标，以适当调节抗真菌反应和治疗方案。