Elucidating the mechanism of macrophage death during infection with the AIDS-associated opportunistic pathogen Histoplasma capsulatum

阐明艾滋病相关机会病原体荚膜组织胞浆菌感染期间巨噬细胞死亡的机制

• 批准号: 10177850
• 负责人: Anita Sil
• 金额: $ 55.33万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-07-10 至 2022-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10177850
• 关键词: AIDS-Related Opportunistic Infections; Acquired Immunodeficiency Syndrome; Africa; Antifungal Agents; Antifungal Therapy; Apoptosis; Apoptotic; Calcium; Calcium-Binding Proteins; Cell Death; Cells; Cellular Stress; Central America; Cessation of life; Cytolysis; Cytosol; Data; Development; Disease; Elongation Factor; Event; Fractionation; Goals; HIV; HIV Infections; Histoplasma capsulatum; Homeostasis; Human; Image; Immune; Immune response; Immunocompromised Host; Immunomodulators; Immunoprecipitation; Individual; Infection; Inhalation; Innate Immune Response; Integration Host Factors; Knockout Mice; Light; Lung diseases; Mammals; Mass Spectrum Analysis; Microbe; Midwestern United States; Molecular; Morbidity - disease rate; Mus; Mycoses; Names; Pathogenesis; Pathogenicity; Pathway interactions; Patients; Phagocytosis; Phagosomes; Phosphorylation; Phosphotransferases; Predisposition; Process; Proliferating; Proteins; Proteomics; Publishing; Research; Resistance; Role; Signal Transduction; Site; Soil; Source; South America; Stress; Systemic disease; Therapeutic; Transcript; Translations; Virulence Factors; Work; biological adaptation to stress; cell mediated immune response; comorbidity; experimental study; fungus; improved; insight; macrophage; mortality; mouse model; novel; opportunistic pathogen; pathogen; pathogenic fungus; pathogenic microbe; response; ribosome profiling; small molecule inhibitor; transcription factor CHOP

Project Summary Histoplasma capsulatum (Hc) is an understudied fungal pathogen that causes fatal disease in immunocompromised individuals with AIDS. Our long-term research goal is to gain insight into the pathogenic mechanisms used by Hc to kill infected immune cells, ultimately resulting in improved understanding and treatment of Hc infections in HIV-infected individuals. Hc is a soil fungus that is endemic in the Midwestern United States, Central and South America, Africa, and other regions of the world. It is introduced into mammalian hosts by inhalation and is subsequently phagocytosed by macrophages. Unlike most microbes, Hc survives and replicates within the macrophage phagosome. Robust proliferation of Hc within the phagosome is followed by host-cell death, thus allowing live fungal cells to escape from the macrophage and undergo subsequent rounds of phagocytosis and intracellular proliferation. Individuals who lack a cell-mediated immune response are more likely to develop severe disseminated disease, and AIDS patients with Hc infection are subjected to prolonged, sometimes lifelong, anti-fungal therapy. We recently discovered that Hc utilizes the secreted effector Cbp1 to trigger an integrated stress response (ISR) in host macrophages, resulting in host cell death after intracellular fungal replication. The ISR is an intracellular signaling cascade that triggers phosphorylation of the α-subunit of the translation elongation factor eIF2 as well as induction of the pro-apoptotic transcription factor CHOP in response to a variety of stresses. We have shown that CHOP is required for host sensitivity to Hc infection in the mouse model of infection. These data are now in press at PLoS Pathogens. To our knowledge, these are the first data that implicate the ISR in the host response to fungal pathogens. However, we still have very little understanding of how Cbp1 induces the ISR. Here we propose to build on robust preliminary data to define the mechanism and consequences of Cbp1-dependent ISR induction during Hc infection. We will: (1) investigate the mechanism of how Cbp1 induces the ISR; (2) elucidate if Cbp1 acts alone during Hc infection to induce the ISR and/or host- cell death, or whether other Hc effectors are involved; and (3) determine the mechanism and role of eIF2α phosphorylation, the central signaling event that initiates the ISR, in response to Hc infection. These studies will explore new strategies used by eukaryotic pathogens to control the viability of macrophages, ultimately developing our understanding of general principles deployed by intracellular microbial pathogens to trigger cellular stress and cause disease. Given the susceptibility of AIDS patients to a variety of intracellular pathogens, the establishment of these general principles may be particular relevant in the context of developing therapeutic strategies (such as ISR inhibition) for AIDS-related opportunistic infections with Hc and other like pathogens.

项目概要 荚膜组织胞浆菌 (Hc) 是一种尚未得到充分研究的真菌病原体，可导致致命疾病 免疫功能低下的艾滋病患者。我们的长期研究目标是深入了解致病菌 Hc 用于杀死受感染免疫细胞的机制，最终提高了理解和 治疗 HIV 感染者的 Hc 感染。 Hc 是一种在中西部地区流行的土壤真菌 美国、中南美洲、非洲及世界其他地区。它被引入到 哺乳动物宿主通过吸入，随后被巨噬细胞吞噬。与大多数微生物不同，Hc 在巨噬细胞吞噬体内存活并复制。 Hc 在吞噬体内的强劲增殖是 随后宿主细胞死亡，从而使活真菌细胞逃离巨噬细胞并经历 随后几轮吞噬作用和细胞内增殖。缺乏细胞介导的免疫的个体 反应更容易发展为严重的播散性疾病，并且感染 Hc 的艾滋病患者 接受长期的、有时是终生的抗真菌治疗。 我们最近发现 Hc 利用分泌效应器 Cbp1 来触发整合应激 宿主巨噬细胞中的反应（ISR），导致细胞内真菌复制后宿主细胞死亡。情报监视与侦察 是一种细胞内信号级联，触发翻译延伸的 α 亚基磷酸化 因子 eIF2 以及促凋亡转录因子 CHOP 的诱导，以响应多种 压力。我们已经证明，在小鼠模型中，CHOP 是宿主对 Hc 感染的敏感性所必需的。 感染。这些数据现已在 PLoS Pathogens 上发表。据我们所知，这些是第一个数据 表明 ISR 与宿主对真菌病原体的反应有关。然而，我们对此仍然了解甚少 Cbp1 如何诱导 ISR。在这里，我们建议建立在可靠的初步数据的基础上来定义机制和 Hc 感染期间 Cbp1 依赖性 ISR 诱导的后果。我们将：（1）研究其机制 Cbp1 如何诱导 ISR； (2) 阐明 Cbp1 在 Hc 感染期间是否单独起作用以诱导 ISR 和/或宿主- 细胞死亡，或是否涉及其他 Hc 效应子； (3)确定eIF2α的机制和作用 磷酸化是响应 Hc 感染而启动 ISR 的中心信号传导事件。这些研究 将探索真核病原体用于控制巨噬细胞活力的新策略，最终 加深我们对细胞内微生物病原体触发的一般原理的理解 细胞应激并导致疾病。鉴于艾滋病患者对多种细胞内毒素的易感性 病原体，这些一般原则的建立可能在以下情况下特别相关： 制定针对 AIDS 相关机会性感染 Hc 和的治疗策略（例如 ISR 抑制） 其他如病原体。