The Role of B Cells and B Cell Toll-like Receptors in Periodontal Disease

描述(由申请人提供)：牙周病(PD)的发病机制的特点是对口腔菌群的慢性免疫反应升高。多种免疫细胞类型在帕金森病中发挥作用，淋巴细胞在疾病进展中相对较晚地渗入感染部位。在帕金森病最严重的患者中，牙龈病变中的大多数细胞是B细胞。提示B细胞在帕金森病发病过程中相对较晚起主导作用。然而，B细胞在帕金森病中的作用在体内还没有得到严格的证实。我们最近证实帕金森病患者的B细胞可以结构性地分泌细胞因子，同时在人牙周病变和帕金森病患者血液中发现Toll样受体(TLR)2和TLR4阳性的B细胞比例升高。功能分析表明，B细胞TLR2和TLR4的激活通常会导致促炎和破骨细胞因子的产生。此外，TLR4配体减少TLR2介导的IL-10的产生，IL-10是一种重要的抗炎细胞因子。在PD患者中发现TLR阳性的B细胞百分比升高，这些B细胞对TLR配体的总体促炎反应，以及B细胞在PD皮损中的普遍存在，表明B细胞TLRs通过调节炎症从而导致骨丢失在PD中发挥重要作用。由于口腔菌群提供了无数的TLR配体，我们的初步数据预测，B细胞TLR在体内通过激活细胞因子直接促进炎症。尽管对人类B细胞TLR功能的更多研究可能在机制和临床上具有重要意义，但这一系列研究的下一个关键步骤是明确证明B细胞和B细胞TLRs在帕金森病中发挥作用。我们假设B细胞TLRs促进炎症和骨丢失，从而加重帕金森病。我们将在经口灌胃的帕金森病小鼠模型中测试这一假说，以确定1.B细胞的缺失；2.仅在B细胞上表达TLR2或TLR4如何影响帕金森病的发病。这些研究将明确地证明B细胞在帕金森病中的作用，以显著扩大对粘膜炎症性疾病中基本B细胞生物学的理解。 公共卫生相关性：牙周病(PD)是一种常见的感染，与包括心血管疾病在内的严重并发症有关。需要新的帕金森病治疗方法来补充目前在许多患者中疗效有限的方案。虽然免疫系统在帕金森病中起着重要作用，但B细胞这一免疫细胞类型的重要性却鲜为人知。来自帕金森病患者的新证据表明，B细胞在帕金森病中发挥着重要作用，但人类受试者的研究本质上不能明确地将B细胞与疾病发病机制联系起来。该项目建议使用模型生物来测试B细胞及其表面受体在帕金森病中的作用，长期目标是寻找治疗帕金森病的新方法。

DESCRIPTION (provided by applicant): Periodontal disease (PD) pathogenesis is characterized by a chronically elevated immune response to the oral flora. Multiple immune cell types play roles in PD, with lymphocytes infiltrating the site of infection relatively late in disease progression. In patients with the most severe PD, the majority of cells in the gingival lesions are B cells. These findings suggest that B cells play a dominant role relatively late in PD pathogenesis. However, the function of B cells in PD has not been rigorously established in vivo. Our recent demonstration that B cells from PD patients constitutively secrete cytokines was accompanied by the discovery of an elevated percentage of Toll-like receptor (TLR) 2 and TLR4-positive B cells in human periodontal lesions and PD patient blood. Functional analyses demonstrate that B cell TLR2 and TLR4 activation generally results in production of pro- inflammatory and osteoclastogenic cytokines. Additionally, TLR4 ligand decreases TLR2-mediated production of IL-10, an important anti-inflammatory cytokine. The discoveries of an elevated percentage of TLR-positive B cells in PD patients, the overall pro-inflammatory responses of these B cells to TLR ligands, and the prevalence of B cells in PD lesions indicate that B cell TLRs play important roles in PD by regulating inflammation thus bone loss. Because the oral flora provides innumerable TLR ligands, our preliminary data predict that B cell TLRs promote inflammation directly through cytokine activation in vivo. Although additional studies on human B cell TLR function are likely to be mechanistically and clinically important, the next critical step in this line of investigation is to unequivocally demonstrate B cells and B cell TLRs play a role in PD. We hypothesize that B cell TLRs promote inflammation and bone loss thus exacerbate PD. We will test this hypothesis in the oral gavage mouse model of PD to determine how 1. absence of B cells; and 2. TLR2 or TLR4 expression only on B cells affect PD pathogenesis. These studies will unequivocally demonstrate roles of B cells in PD to significantly expand the understanding of basic B cell biology in mucosal inflammatory diseases. PUBLIC HEALTH RELEVANCE: Periodontal Disease (PD) is a common infection linked to serious complications including cardiovascular disease. Novel PD treatments are needed to supplement current regimens, which have limited effectiveness in many patients. Although the immune system plays an important role in PD, the importance of one immune cell type, B cells, is poorly understood. New evidence from PD patients suggests that B cells play important roles in PD, but human subjects research, by its nature, cannot definitively link B cells to disease pathogenesis. The project proposes to test the role of B cells and their surface receptors in PD using model organisms with a long-term goal of identifying new treatments for PD.