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

莱姆病的大多数症状是由于宿主对生物体疏螺旋体的免疫反应 即使没有抗生素治疗，也会随着时间的推移而消退。在其自然宿主中， 尽管该生物体持续存在，但仍然可以看到感染。在人类和近亲繁殖的小鼠（ 发展对生物体的免疫反应），炎症被认为是由先天免疫缺陷的受体启动的。 免疫系统在体外，识别B的先天性病原体感应受体丧失。如toll- Like receptor 2（TLR 2）导致炎症反应降低。然而，动物体内研究 缺乏这些受体或它们的衔接分子并不表现出减少炎症，并且在许多情况下， 显示炎症增加。最近，在人类中，tlr 1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细胞因子与细胞因子受体表达增加有关。 炎症和症状。这表明，在最初的刺激后，这些先天免疫的主要作用是， 分子的作用是抑制炎症。体外研究和体内研究之间的一个主要区别是 体外实验通常通过测量几分钟到几小时的反应来进行 在接触到有机体后。我们有证据表明，更长时间的体外暴露会导致 对B刺激的先天免疫“耐受性”的发展。伯格多费里。 在本提案中，我们将研究tlr 1 - 1805 GG 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。1805 GG SNP导致定位到细胞的丢失。 细胞表面，但不影响受体的活性。因此，在目标1中，我们将首先确定 SNP对特异性、定位依赖性信号通路和下游细胞因子的影响 应答我们之前已经证明TLR 1/TLR 2配体Pam 3CSK 4可以启动来自两个细胞的信号传导， 细胞内和细胞表面位置，尽管每个位置的信号不同。很可能是tlr 1- 1805 GG SNP继续在内体上发信号。我们也会追踪受体和配体的运动 tlr 1缺失与tlr 1 - 1805 GG SNP的比较。在目标2中，我们将评估tlr 1 - 1805 GG SNP在 导致对B的先天免疫耐受性丧失。burgdorferi。我们将专注于 了解其对巨噬细胞极化，细胞死亡和葡萄糖代谢的作用。最后在 目的3、利用等基因B。我们将确定是否启动耐药性的伯氏分离株的作用， 在调节巨噬细胞重编程和耐受性丧失中生物体的特定组分。 我们相信B。Burgdorferi感染，其中存在长期感染，且几乎没有证据表明 随着时间的推移，炎症，是一个很好的模型，以了解免疫系统如何控制反应， 侵入性细菌对健康的威胁小于持续清除感染的努力-本质上 通过先天性免疫耐受的发展使生物体成为入侵性的“寄生虫”。

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.