Deciphering a novel lipid-based mechanism of innate immune modulation

破译一种新型的基于脂质的先天免疫调节机制

基本信息

批准号：
10726010
负责人：
Roarke Alexander Kamber
金额：
$ 24.23万
依托单位：
UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
依托单位国家：
美国
项目类别：
财政年份：
2023
资助国家：
美国
起止时间：
2023-05-23 至 2025-04-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10726010
关键词：
ANXA2 gene Animals Antibodies Antifungal Agents Biological Blood Circulation Bone Marrow CRISPR screen Candida albicans Cell surface Cells Clustered Regularly Interspaced Short Palindromic Repeats Coculture Techniques Data Dendritic Cells Dendritic cell activation Disease Disseminated candidiasis Dyes Exhibits Exposure to Fatty Acids Foundations Fungal Components Genes Genomic DNA Host Defense Hour Human Hydrolysis IL17 gene Immune Immune response Immunity Immunosuppression In Vitro Incubated Infection Integration Host Factors Interleukin-1 beta Interleukin-6 Invaded Kidney Knock-out Knockout Mice Libraries Lipase Lipids Macrophage Mediating Messenger RNA Microbe Modeling Molecular Morphogenesis Mucocutaneous Candidiasis Mus Mycoses Natural Immunity Nonesterified Fatty Acids Organ Palmitic Acids Pathogenesis Production Proteins Role Sepsis Signal Pathway Signal Transduction Solid Sorting Source Stains Systemic infection T-Lymphocyte TLR2 gene TLR4 gene Testing Tissues Virulence Work Yeasts cell preparation cell type cytokine experimental study genetic approach genome-wide gut microbiota high risk immune activation immunoregulation innate immune mechanisms insight interleukin-23 mouse model mutant new therapeutic target novel pathogen pathogenic bacteria pathogenic fungus pathogenic virus prevent response

项目摘要

Our understanding of antifungal immunity remains relatively limited, and examples of fungal mechanisms to modulate these responses are even rarer. C. albicans is a ubiquitous fungal component of mammalian gut microbiota as well as the most common cause of fungal infections in humans. We identified the lip2-/- virulence mutant in a screen of ~1500 C. albicans mutants in a mouse model of systemic infection (Basso et al., Cell Host and Microbe, in press). Whereas a lip2-/- strain exhibits normal virulence attributes during the first 6 hours of infection, including dissemination through the bloodstream, solid organ invasion, and yeast-to-hypha morphogenesis, its titers progressively decline at subsequent timepoints, and the host typically survives. Immune profiling of infected kidneys (the primary target organ in this infection model) revealed significant increases in levels of IL-17 mRNA and protein in organs infected with lip2-/- compared to wild-type C. albicans (WT). Strikingly, the virulence of lip2-/- was fully restored when infections were performed in Il17af-/- animals that fail to produce IL-17. These results suggested that 1) IL-17 is required for a potent antifungal response during systemic candidiasis and 2) Lip2 somehow opposes this response. We identified renal 𝛄δ T cells as a major source of IL- 17 in lip2-/--infected kidneys and renal dendritic cells as a major source of IL-23 (a cytokine known to stimulate IL-17 production by 𝛄δ T cells). Further, under in vitro conditions, we observed that lip2-/- (but not WT C. albicans) activates IL-23 expression by co-cultured bone marrow-derived dendritic cells (BMDCs). Using BMDCs prepared from Tlr2-/-, Tlr4-/-, Tlr2/Tlr4-/-, and Clec7a-/- animals, we further showed that TLR2 and/or TLR4 but not Dectin-1 are required for this response. Remarkably, immune activation was blocked when the coculture experiment is performed in the presence of 0.1 𝛍M palmitic acid, a hydrolysis product of Lip2. The data support a model in which WT C. albicans secretes Lip2 in solid organs, thereby raising local concentrations of palmitic acid, which suppresses TLR2- and TLR4-dependent activation of tissue-resident DCs and, thereby, a downstream IL-17- dependent antifungal immune response. Beyond unveiling a novel fungal virulence mechanism, this work unveils a role for IL-17 during systemic fungal infection, in addition to its previously well-documented role in defense against mucocutaneous candidiasis. To understanding this novel lipid-mediated modulation of the innate response to C. albicans, we will use a forward genetic approach to identify factors required for modulation of the innate responses to C. albicans by free fatty acids produced by its lipase activity. These exploratory, high-risk studies will provide insights lipid-mediated immunosuppression, a novel mechanism of fungal pathogenesis and immune modulation.

我们对抗真菌免疫的理解仍然相对有限，真菌机制的例子调节这些响应甚至更罕见。白色念珠菌是哺乳动物肠道无处不在的真菌成分微生物群以及人类真菌感染的最常见原因。我们确定了lip2 - / - 病毒性在〜1500 C的筛网中的突变体在全身感染的小鼠模型中的白色唱片突变体和微生物，印刷中）。 lip2 - / - 菌株在最初6小时内表现出正常的病毒属性感染，包括通过血液传播，固体器官入侵和酵母到河口形态发生，其滴度在随后的时间点上逐渐下降，宿主通常可以生存。免疫受感染儿童的分析（此感染模型中的主要目标器官）显示出显着增加与野生型白色念珠菌（WT）相比，感染LIP2 - / - 的器官中IL-17 mRNA和蛋白质水平。令人惊讶的是，当在IL17AF - / - 未能进行感染进行感染时，LIP2 - / - 的病毒已完全恢复产生IL-17。这些结果表明1）在系统性期间具有潜在的抗真菌反应需要IL-17 念珠菌病和2）LIP2以某种方式反对这种反应。我们将肾𝛄δT细胞确定为IL-的主要来源 17在LIP2 - / - 被感染的肾脏和肾脏树突状细胞作为IL-23的主要来源（已知刺激的细胞因子 𝛄δT细胞产生IL-17）。此外，在体外条件下，我们观察到lip2 - / - （但不是WT C.白色念珠菌）通过共培养的骨髓衍生的树突状细胞（BMDC）激活IL-23的表达。使用准备的BMDC 来自TLR2 - / - ，TLR4 - / - ，TLR2/TLR4 - / - 和CLEC7A - / - 动物，我们进一步表明TLR2和/或TLR4但没有Dectin-1 值得注意的是，当共培养实验是在0.1 𝛍M棕榈酸的存在下进行，这是LIP2的水解产物。数据支持模型白色念珠菌在固体器官中的lip2 wt，从而增加了局部浓度的棕榈酸，其中抑制组织居民DC的TLR2-和TLR4依赖性激活，从而抑制下游IL-17-- 依赖性抗真菌免疫反应。除了揭开一种新型的真菌病毒机制，这项工作揭幕了 IL-17在系统性真菌感染过程中的作用，除了其先前有据可查的防御作用抗粘膜念珠菌病。了解这种新颖的脂质介导的先天调节对白色念珠菌的反应，我们将使用一种前瞻性遗传方法来确定调制所需的因素由其脂肪酶活性产生的游离脂肪酸对白色念珠菌的天生反应。这些探索性高风险研究将提供见解脂质介导的免疫抑制，一种新颖的真菌发病机理和免疫调节。