Role of human innate immune mutations in loss of tolerance to Borrelia burgdorferi

人类先天免疫突变在伯氏疏螺旋体耐受性丧失中的作用

• 批准号: 10256713
• 负责人: Linden T Hu
• 金额: $ 59.05万
• 依托单位: TUFTS UNIVERSITY BOSTON
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-08 至 2025-08-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10256713
• 关键词: Affect; Amino Acids; Animals; Antibiotic Therapy; Arthritis; Bacteria; Belief; Biological Assay; Borrelia burgdorferi; Carditis; Cell Death; Cell Line; Cell surface; Cells; Clinical; Collaborations; Confocal Microscopy; Dangerousness; Data; Defect; Development; Disease; Exanthema; Exhibits; Exposure to; Failure; Fatigue; Genes; Health; Heterodimerization; Hour; Human; Human Genetics; Human Inbreeding; Immune; Immune Tolerance; Immune response; Immune system; Immunologic Receptors; In Vitro; Inbred Mouse; Infection; Inflammation; Inflammatory; Inflammatory Response; Innate Immune System; Isoleucine; Knock-out; Laboratories; Life; Ligands; Link; Lipoproteins; Location; Lyme Arthritis; Lyme Disease; Measures; Mediating; Meningitis; Metabolism; Modeling; Movement; Mutation; Natural Immunity; Neurocognitive; Organism; Pain; Pathway interactions; Patients; Process; Reaction; Reporting; Research Personnel; Risk; Role; Serine; Signal Pathway; Signal Transduction; Signaling Molecule; Single Nucleotide Polymorphism; Site; Stimulus; Symptoms; Syndrome; TLR1 gene; TLR2 gene; Testing; Time; Ursidae Family; Vector-transmitted infectious disease; acute infection; cell type; cytokine; experimental study; flu; glucose metabolism; immune clearance; in vivo; individual patient; macrophage; mouse model; mutant; pathogen; persistent symptom; polarized cell; receptor; receptor expression; response; trafficking; weapons

The majority of symptoms of Lyme disease are due to the host immune response to the organism, Borrelia burgdorferi, and resolve over time, even without antibiotic treatment. In its natural host, little or no reaction to infection can be seen despite the fact that the organism persists for life. In humans and inbred mice (which do develop immune responses to the organism), inflammation is thought to be initiated by receptors of the innate immune system. In vitro, loss of innate, pathogen-sensing receptors that recognize B. burgdorferi such as toll- like receptor 2 (TLR2) results in a decrease inflammatory response. However, in vivo studies of animals deficient in these receptors or their adaptor molecules do not show reduced inflammation and in many cases show increased inflammation. Recently, in humans, a single nucleotide polymorphism (SNP) in the tlr1 gene that results in loss of expression of the receptor on the cell surface was found to be associated with increased inflammation and symptoms. This suggests that after the initial stimulus, a major role for these innate immune molecules is in dampening inflammation. One major difference between in vitro studies and the in vivo infections is that the in vitro experiments are typically conducted by measuring responses minutes to hours after exposure to the organism. We have evidence that more prolonged exposures in vitro result in the development of innate immune “tolerance” to stimulation by B. burgdorferi. In this proposal, we will study the role of the tlr1-1805GG SNP in disrupting innate immune tolerance, thereby leading to excessive inflammatory responses. The 1805GG SNP results in a loss of localization to the cell surface but does not affect the activity of the receptor. Therefore, in Aim 1, we will first determine the effects of the SNP on specific, localization-dependent signaling pathways and downstream cytokine responses. We have previously shown that the TLR1/TLR2 ligand Pam3CSK4 can initiate signaling from both intracellular and cell surface locations although the signals are different in each location. It is likely that the tlr1- 1805GG SNP continues to signal endosomally. We will track movements of the receptors and ligands as well as compare a tlr1 deletion to the tlr1-1805GG SNP. In Aim 2, we will assess the role of the tlr1-1805GG SNP on macrophage reprogramming leading to loss of innate immune tolerance to B. burgdorferi. We will focus on understanding its effects on macrophage polarization, cell death and the role of glucose metabolism. Finally, in Aim 3, using isogenic B. burgdorferi isolates that do or do not initiate tolerance, we will identify the role of specific components of the organism in moderating macrophage reprograming and loss of tolerance. We believe that B. burgdorferi infection, where there is prolonged infection with minimal evidence of inflammation over time, is an excellent model to understand how the immune system can control responses to invasive bacteria that pose less threat to health than continued efforts to clear the infection—in essence making the organism an invasive “commensal” through the development of innate immune tolerance.

莱姆病的大多数症状是由于宿主对伯氏疏螺旋体的免疫反应造成的 即使没有抗生素治疗，伯氏杆菌也会随着时间的推移而消退。在其自然宿主中，很少或没有反应 尽管该生物体终生存在，但仍然可以看到感染。在人类和近交系小鼠中（这确实 对生物体产生免疫反应），炎症被认为是由先天性受体引发的 免疫系统。在体外，识别伯氏疏螺旋体的先天病原体感应受体（例如 toll- 样受体 2 (TLR2) 会导致炎症反应减少。然而，动物体内研究 缺乏这些受体或其衔接分子并不能减少炎症，并且在许多情况下 显示炎症增加。最近，在人类中，tlr1 基因中的单核苷酸多态性 (SNP) 导致细胞表面受体表达丧失的结果被发现与增加 炎症和症状。这表明在最初的刺激之后，这些先天免疫发挥了主要作用 分子具有抑制炎症的作用。体外研究与体内研究的一大区别 感染的原因是体外实验通常是通过测量几分钟到几小时的反应来进行的 接触有机体后。我们有证据表明，更长时间的体外暴露会导致 对伯氏疏螺旋体刺激的先天免疫“耐受性”的发展。 在本提案中，我们将研究 tlr1-1805GG SNP 在破坏先天免疫耐受中的作用， 从而导致过度的炎症反应。 1805GG SNP 导致定位丢失 但不影响细胞表面受体的活性。因此，在目标 1 中，我们首先要确定 SNP 对特定的、定位依赖性信号通路和下游细胞因子的影响 回应。我们之前已经证明 TLR1/TLR2 配体 Pam3CSK4 可以启动来自两者的信号传导 细胞内和细胞表面位置，尽管每个位置的信号不同。很可能 tlr1- 1805GG SNP 继续在内体发出信号。我们还将跟踪受体和配体的运动 将 tlr1 缺失与 tlr1-1805GG SNP 进行比较。在目标 2 中，我们将评估 tlr1-1805GG SNP 的作用 巨噬细胞重编程导致对伯氏疏螺旋体失去先天免疫耐受。我们将重点关注 了解其对巨噬细胞极化、细胞死亡的影响以及葡萄糖代谢的作用。最后，在 目标 3，使用能够或不引发耐受性的同基因伯氏疏螺旋体分离株，我们将确定 生物体的特定成分可调节巨噬细胞重编程和耐受性丧失。 我们认为，伯氏疏螺旋体感染存在长期感染，且证据极少。 随着时间的推移，炎症是了解免疫系统如何控制对炎症的反应的绝佳模型。 从本质上讲，与持续努力清除感染相比，入侵细菌对健康的威胁要小 通过先天免疫耐受的发展，使生物体成为侵入性“共生体”。