In vivo inflammatory challenge to elucidate the role of the toll-like receptor 4 pathway in depression

体内炎症挑战阐明 Toll 样受体 4 通路在抑郁症中的作用

• 批准号: 10448689
• 负责人: Leandra Kali Figueroa-Hall
• 金额: $ 10万
• 依托单位: LAUREATE INSTITUTE FOR BRAIN RESEARCH
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-04-01 至 2024-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10448689
• 关键词: Acids; Acute; Astrocytes; Behavioral; Blood; Blood - brain barrier anatomy; Brain; C-reactive protein; Chronic stress; Clinical Data; Clinical Research; Clinical assessments; Data; Depressed mood; Detection; Disease; Double-Blind Method; Endotoxemia; Exposure to; Flow Cytometry; Hour; IL8 gene; Immune; Immune response; Immune signaling; Immune system; Immunoassay; Immunologics; Impairment; Individual; Inflammation; Inflammatory; Inflammatory Response; Infusion procedures; Interleukin-1; Interleukin-6; Investigation; Lead; Leaky Gut; Ligands; Lipopolysaccharides; Major Depressive Disorder; Mediating; Medicine; Mental Depression; Messenger RNA; MicroRNAs; Microglia; Molecular; Moods; Participant; Pathogenesis; Pathway interactions; Pattern; Peripheral; Phase; Physiological; Placebos; Plasma; Play; Production; Proteins; Psychiatry; RNA; Randomized; Recording of previous events; Regulation; Research Personnel; Risk; Role; Saline; Sampling; Serum; Severities; Signal Transduction; Stress; Suggestion; TLR4 gene; TNF gene; Techniques; Time; Training; Visit; cytokine; depressive symptoms; detection platform; evidence base; extracellular vesicles; immunoregulation; in vivo; lymphotoxin beta; microbial; new therapeutic target; next generation sequencing; novel; pathogen; placebo controlled study; preclinical study; primary outcome; response; safety assessment; transcriptome sequencing

Project Summary Approximately 1/3 of individuals with major depressive disorder (MDD) display inflammation that is believed to play a causal role in the disorder, but the precise mechanisms are not understood. Experimental endotoxemia studies in healthy individuals have shown behavioral, immunological, and physiological changes leading to a transient depressive-like state that resolves 4-5 hours after administration of lipopolysaccharide (LPS). While informative, these studies cannot reveal putative, aberrant inflammatory and regulatory mechanisms in MDD. Hence, a mechanistic approach is required to pinpoint which immunoregulatory mechanisms are defective in MDD. This proposal will leverage an experimental medicine study involving acute administration of LPS or saline to individuals with MDD and healthy controls (HC) to identify depression-relevant changes in the TLR4 pathway and its regulation by microribonucleic acids (miRNAs) in both the blood and the brain. The central hypothesis is that TLR4 signaling is sensitized in MDD by a history of exposure to exogenous (e.g. pathogens, LPS from leaky gut) and/or endogenous (e.g. chronic stress) ligands, and thus, TLR4-mediated inflammatory and regulatory mechanisms are impaired in MDD subjects compared to HC. TLR4 detects pathogen- and damage-associated molecular patterns (PAMPs and DAMPs) for production of inflammatory cytokines, such as interleukin 6 (IL-6) and tumor necrosis factor (TNF), which are elevated in some individuals with MDD. Whilst PAMPs, like LPS play a role in the pathogenesis of MDD, stress-associated production of DAMPs may also activate TLR4. Despite the theoretical importance of the TLR4 pathway, the evidence base is currently small, the extant clinical data are cross-sectionally derived, and TLR4 downstream signaling has not been assessed despite aberrant expression of TLR4-responsive miRNAs in MDD. These miRNAs can be isolated from extracellular vesicles (EVs) that cross the blood brain barrier, thus, isolating EVs of glial origin will provide a readout of CNS-associated TLR4 regulation in MDD. Our preliminary data suggest that the inflammatory cytokines, IL-6 and TNF, as well as TLR4 are increased in MDD compared to HC in response to LPS. The K99 phase will identify peripheral and central TLR4-mediated immune signaling mechanisms in MDD with the use of high-sensitivity, immunoassay detection to identify changes in cytokine expression and TLR4 pathway proteins and support the PI’s training in flow cytometry, miRNA extraction, astrocyte-enriched EV (AEEV) isolation, and RNA-seq. The R00 phase will identify peripheral and central TLR4-mediated regulatory mechanisms in MDD with the use of Next Generation Sequencing to identify miRNAs dysregulated in MDD and will provide support for transition to an independent investigator specializing in CNS-dependent TLR4- inflammatory mechanisms in depression. The ability to delineate TLR4-mediated peripheral and CNS immunoregulatory responses with cutting edge techniques, still novel to the field of psychiatry, will move us one step closer to understanding the mechanisms underlying inflammation-associated depression.

项目摘要 大约三分之一的重度抑郁症（MDD）患者表现出炎症，据信炎症是导致抑郁症的原因之一。 在疾病中起着因果作用，但确切的机制尚不清楚。实验性内毒素血症 对健康个体的研究表明，行为、免疫和生理变化导致 暂时性抑郁样状态，在给予脂多糖（LPS）后4-5小时消退。而 这些研究不能揭示MDD中假定的异常炎症和调节机制。 因此，需要一种机制方法来确定哪些免疫调节机制是有缺陷的， MDD。该提案将利用涉及急性施用LPS或LPS的实验医学研究。 生理盐水与MDD和健康对照（HC）的个人，以确定抑郁症相关的变化TLR 4 在血液和大脑中，微核糖核酸（miRNAs）可以调节这一途径。中央 假设是MDD中TLR 4信号传导因接触外源性（例如病原体， 来自漏肠的LPS）和/或内源性（例如慢性应激）配体，并且因此，TLR 4介导的炎性 与HC相比，MDD受试者的调节机制受损。TLR 4检测病原体， 损伤相关分子模式（PAMP和DAMP），用于产生炎性细胞因子，如 白细胞介素6（IL-6）和肿瘤坏死因子（TNF），在一些MDD患者中升高。虽然 PAMPs和LPS一样在MDD的发病机制中起作用，应激相关的DAMPs的产生也可能 激活TLR 4。尽管TLR 4通路在理论上很重要，但目前的证据基础很小， 现有的临床数据是横断面的，TLR 4下游信号还没有被评估 尽管MDD中TLR 4应答性miRNA的表达异常。这些miRNAs可以从 细胞外囊泡（EV）穿过血脑屏障，因此，分离神经胶质来源的EV将提供 MDD中CNS相关TLR 4调节的读数。我们的初步数据表明， 与HC相比，MDD中细胞因子IL-6和TNF以及TLR 4响应于LPS而增加。K99 阶段将确定外周和中枢TLR 4介导的免疫信号传导机制在MDD中的使用 高灵敏度的免疫检测，以确定细胞因子表达和TLR 4通路的变化 蛋白质，并支持PI在流式细胞术，miRNA提取，星形胶质细胞富集EV（AEEV） 分离和RNA-seq. R 00阶段将鉴定外周和中枢TLR 4介导的调节性细胞因子。 使用下一代测序技术鉴定MDD中失调的miRNAs 并将为过渡到专门从事CNS依赖性TLR 4的独立研究者提供支持， 抑郁症的炎症机制描述TLR 4介导的外周和CNS的能力 免疫调节反应与尖端技术，仍然新颖的精神病学领域，将推动我们 更接近了解炎症相关抑郁症的机制。