Role of JAK2 in Innate Immunity

描述（由申请人提供）：牙龈卟啉单胞菌被认为是牙周病的主要病原体之一。评估宿主对牙龈卟啉单胞菌的炎症反应的研究已经证明，先天免疫受体TLR 2和TLR 4是参与识别LPS和从牙龈卟啉单胞菌分离的各种病原体相关分子模式的主要TLR。然而，如体外和体内研究所证实的，TLR 2已被证明是参与调节对牙龈卟啉单胞菌的全菌的先天免疫应答的主要TLR。研究表明，TLR 2的缺乏导致宿主炎症的消除或抑制，细菌清除的增强和骨丢失的减弱。因此，由牙龈卟啉单胞菌诱导的TLR 2介导的炎症反应似乎对于其加剧疾病过程的能力至关重要。由于TLR 2在介导对全细胞牙龈卟啉单胞菌的炎症反应中的主要重要性，我们专注于TLR 2激活的细胞内信号传导途径，并随后确定Janus激酶2（JAK 2）在控制先天性炎症反应中起着至关重要的作用。我们的具体假设是JAK 2是控制牙龈卟啉单胞菌刺激的先天免疫细胞介导的TLR 2炎症的中心激酶，因此在疾病过程中起着重要作用。这一假设基于：1）用牙龈卟啉单胞菌刺激先天免疫细胞[人牙龈上皮细胞（EC）、树突状细胞（DC）和巨噬细胞]导致JAK 2的TLR 2依赖性活化，并且JAK 2的抑制减弱炎症反应;（2）用牙龈卟啉单胞菌刺激先天免疫细胞导致活化的JAK 2与TLR 2的胞质结构域结合;（3）来自牙龈卟啉单胞菌刺激的细胞的TLR 2的免疫沉淀证明JAK成员JAK 2、JAK 3和TYK 2与TLR 2的缔合;（4）JAK 2的抑制导致牙龈卟啉单胞菌介导的TLR 2的酪氨酸磷酸化的丧失以及JAK 2、JAK 3和TYK 2向TLR 2的募集的丧失;（5）JAK 2的抑制导致NF-：B p65信号传导途径的消除的激活;（6）JAK 2在用牙龈卟啉单胞菌攻击的小鼠中被激活;和（7）JAK 2的体内抑制消除了用牙龈卟啉单胞菌攻击的小鼠中的宿主炎症反应。这些初步发现首次表征了JAK 2在调节TLR 2介导的先天免疫应答中的功能性细胞信号传导途径，包括JAK如何被激活并募集至TLR 2，并且已经鉴定了TLR 2激活/募集JAK至TLR 2的能力是涉及对牙龈卟啉单胞菌的炎症应答的基本过程。具体目标将定义JAK 2通路在调节宿主对牙龈卟啉单胞菌的炎症反应中发挥的功能作用，并通过确定JAK 2抑制如何影响小鼠模型中牙龈卟啉单胞菌诱导宿主炎症和骨丢失的能力来评估体内靶向JAK 2的重要性。 牙周炎是一种慢性炎症性疾病。宿主的免疫反应已被证明通过控制炎症反应在疾病过程中发挥重要作用。因此，定义和表征宿主如何控制炎症反应对于确定潜在的治疗干预至关重要。

DESCRIPTION (provided by applicant): Porphyromonas gingivalis is considered to be one of the major etiologic agents of periodontal diseases. Studies assessing the host inflammatory response to P. gingivalis have demonstrated that the innate immune receptors, TLR2 and TLR4, are the major TLRs involved in the recognition of both the LPS and various pathogen associated molecular patterns isolated from P. gingivalis. However, as demonstrated from both in vitro and in vivo studies, TLR2 has been documented to be the predominant TLR involved in regulating the innate immune response to the whole bacterium of P. gingivalis. Studies have shown that the absence of TLR2 results in abrogated or suppressed host inflammation, enhanced bacterial clearance, and attenuated bone loss. Thus, the TLR2-mediated inflammatory response induced by P. gingivalis appears to be critical for its ability to exacerbate the disease process. Due to the primary importance of TLR2 in mediating the inflammatory response to whole-cell P. gingivalis, we focused on the intracellular signaling pathways activated by TLR2 and have subsequently identified that the Janus Kinase 2 (JAK2) plays an essential role in controlling the innate inflammatory response. Our specific hypothesis is that JAK2 is a central kinase controlling TLR2- mediated inflammation by P. gingivalis-stimulated innate immune cells and thus plays an essential role in the disease process. This hypothesis is based on: 1) stimulation of innate immune cells [human gingival epithelial cells (EC), dendritic cells (DC), and macrophages] with P. gingivalis resulted in the TLR2-dependent activation of JAK2, and inhibition of JAK2 attenuated the inflammatory response; (2) stimulation of innate immune cells with P. gingivalis resulted in the association of activated JAK2 with the cytosolic domain of TLR2; (3) immunoprecipitation of TLR2 from P. gingivalis-stimulated cells demonstrated the association of JAK members JAK2, JAK3, and TYK2 with TLR2; (4) inhibition of JAK2 resulted in the loss of P. gingivalis-mediated tyrosine phosphorylation of TLR2 and loss of JAK2, JAK3, and TYK2 recruitment to TLR2; (5) inhibition of JAK2 resulted in the abrogated activation of the NF-:B p65 signaling pathway; (6) JAK2 was activated in mice challenged with P. gingivalis; and (7) in vivo inhibition of JAK2 abrogated the host inflammatory response in mice challenged with P. gingivalis. These preliminary findings are the first to characterize a functional cell- signaling pathway for JAK2 in regulating TLR2-mediated innate immune responses, including how JAKs are activated and recruited to TLR2, and have identified that the ability of TLR2 to activate/recruit JAKs to TLR2 is a fundamental process involved in the inflammatory response to P. gingivalis. The Specific Aims will define the functional role the JAK2 pathway plays in regulating the host inflammatory response to P. gingivalis, and assess the importance of targeting JAK2 in vivo by determining how JAK2 inhibition affects the ability of P. gingivalis to induce host inflammation and bone loss in a mouse model. PUBLIC HEALTH RELEVANCE: Periodontitis is a chronic inflammatory disease. The host's immune response has been shown to play a fundamental role in the disease process by controlling the inflammatory response. Thus, defining and characterizing the how the host controls the inflammatory response is critical for identifying potential therapeutic interventions.