Pathogenic and Diagnostic Implications of MicroRNAs in Lyme Disease.

莱姆病关节炎（LA）是伯氏疏螺旋体感染的一种常见的晚期表现，通常在适当的抗生素治疗后消退。然而，在一些患者中，口服和静脉注射抗生素治疗2-3个月后，螺旋体明显死亡，关节炎持续数月或数年，称为抗生素难治性LA。这些患者的关节以滑膜过度炎症和增生为特征。MicroRNAs （miRNAs）是炎症和增殖等多种生物过程的重要调节因子，miRNA功能缺陷的小鼠对伯氏疏螺旋体感染和更严重的莱姆病关节炎的免疫反应显著改变。然而，mirna在人类LA中的作用尚未得到证实。为了确定miRNA如何调节人类LA，进行了无偏筛选，以测量抗生素难治性LA患者滑膜液（SF）和滑膜组织中的miRNA表达。感染性LA（静脉抗生素治疗前）、RA（一种典型的慢性关节炎症）或骨关节炎（OA，一种轻度炎症性关节疾病）患者作为对照组。LA和RA患者的滑膜组织和SF中含有炎性miRNA特征，包括miR- 146a和miR-155。在抗生素难治性LA患者中，这种炎症性miRNA特征与炎症标志物升高和疾病持续时间延长相关。除了炎症特征外，抗生素难治性LA和RA患者还具有明显的增殖性miRNA特征，包括miR-142和miR-223。相比之下，感染性LA（口服或静脉抗生素治疗前）或OA患者缺乏这种增生性特征。利用滑膜病变中主要的常驻细胞成纤维细胞进行的体外研究表明，从LA患者SF中分离的miRNAs可转移到成纤维细胞样滑膜细胞中，这表明miRNAs可能在LA发病过程中作为常驻细胞基因表达的旁分泌调节因子。基于这些初步结果，我们提出抗生素治疗后，抗生素反应性LA患者可适当下调炎症并修复受损组织，从而导致关节炎的消退。相比之下，抗生素难治性LA患者在明显的螺旋体杀死后无法恢复体内平衡，并且对感染的免疫反应开始发展为不受控制的滑膜炎症和增殖。在这些患者中，炎症性mirna的积累表明不能下调免疫反应，而增殖性mirna的积累表明不能适当调节增殖和组织修复。本研究旨在确定mirna在人类LA发病机制中调节滑膜炎症和增殖的作用，并探索mirna作为感染诱导的慢性炎症患者的新生物标志物和治疗靶点的潜力。

Lyme arthritis (LA), a common late manifestation of infection with Borrelia burgdorferi, usually resolves after appropriate antibiotic therapy. However, in some patients arthritis persist for months or years following apparent spirochetal killing by 2-3 months of oral and IV antibiotic therapy, termed antibiotic-refractory LA. Joints in these patients are characterized by excessive synovial inflammation and proliferation. MicroRNAs (miRNAs) are important regulators of various biological processes such as inflammation and proliferation, and mice with defects in miRNA function have significantly altered immune responses to B. burgdorferi infection and more severe Lyme arthritis. However, the role of miRNAs has not yet been examined in human LA. To determine how miRNAs modulate human LA, an unbiased screen was performed to measure miRNA expression in synovial fluid (SF) and synovial tissue from antibiotic-refractory LA patients. Patients with infectious LA (before IV antibiotic therapy), RA (a prototypic chronic joint inflammatory disease), or osteoarthritis (OA, a minimally inflammatory joint disease) were used as comparison groups. Synovial tissue and SF from patients with LA and RA, but not OA, contained an inflammatory miRNA signature, including miR- 146a and miR-155. In patients with antibiotic-refractory LA, this inflammatory miRNA signature correlated with elevated inflammatory markers and longer disease duration. In addition to an inflammatory signature, antibiotic-refractory LA and RA patients had a distinct proliferative miRNA signature, including miR-142 and miR-223. In contrast, infectious LA (prior to oral or IV antibiotic therapy) or OA patients lacked this proliferative signature. In vitro studies using fibroblasts, the predominant resident cell in the synovial lesion, demonstrated that miRNAs isolated from SF of LA patients are transferred to fibroblast-like synoviocytes, suggesting miRNAs may act as paracrine regulators of gene expression in resident cells during LA pathogenesis. Based on these preliminary results, it is proposed that after antibiotic therapy, patients with antibiotic- responsive LA appropriately down-regulate inflammation and repair damaged tissue, leading to resolution of arthritis. In contrast, patients with antibiotic-refractory LA fail to restore homeostasis following apparent spirochetal killing, and what starts as an immune response to infection develops into uncontrolled synovial inflammation and proliferation. In these patients, accumulation of inflammatory miRNAs indicates a failure to down-modulate immune responses, and accumulation of proliferative miRNAs indicates a failure to appropriately regulate proliferation and tissue repair. This proposal aims to determine the roles of miRNAs in regulating synovial inflammation and proliferation in human LA pathogenesis, and to explore the potential of miRNAs as novel biomarkers and therapeutic targets for patients with infection-induced chronic inflammation.