The Role of MAPK-Activated Protein Kinase 2 in Periodontal Disease

描述（由申请人提供）：大约50%的30岁及以上的美国人患有牙周病。随着牙周病的发展，炎症最终会导致不可逆转的骨质和牙齿流失。丝裂原活化蛋白激酶（MAPKs）在牙周病期间调节先天宿主炎症反应。丝裂原活化蛋白激酶活化蛋白激酶2 （MK2）是p38 MAPK的下游靶点，在侵袭性牙周病动物模型中调节巨噬细胞的炎症。巨噬细胞和破骨细胞都来源于单核细胞谱系，表达表面趋化因子受体，这对于从循环到感染周围部位的趋化至关重要。我们项目实验室之前的结果表明，A.放线菌comitans，一种侵袭性牙周病病原体，和A.放线菌comitans脂多糖（LPS）激活MK2。在A. actinomycetemcomitans lps驱动的大鼠模型中，MK2正调控炎症浸润和骨质流失。初步数据支持MK2在cd11bi -表达细胞上调节CXCR4细胞表面表达的作用，提示趋化因子受体表达的调节可能是MK2抑制下减少巨噬细胞浸润的重要机制。与MK2 +/+ (WT)相比，MK2 -/- CD11blo破骨细胞祖细胞（OCPs）中lps驱动的破骨细胞形成减少支持了MK2信号传导对病理性破骨细胞形成至关重要。在小鼠颅骨模型中，MK2信号传导对于a .放线菌诱导的骨质流失也至关重要。这些数据支持了我们的假设，即在宿主-病原体相互作用过程中，MK2信号是单核细胞趋化和随后分化为巨噬细胞和破骨细胞所必需的。为了解决这一假设，我们将使用骨髓移植来创建MK2嵌合动物，然后使用“气囊模型”来评估A.放线菌（A. actinomycetemcomitans）攻击下造血MK2信号在单核细胞趋化中的作用（Aim #1）。MK2信号在A.放线菌（A. actinomycetemcomitans）诱导的破骨细胞生成中与破骨细胞生成的主要转录因子NFATc1相关的机制将在体外使用ocp进行研究。小鼠颅骨骨丢失模型将用于证实MK2对于A.放线菌comitans驱动的体内破骨细胞生成至关重要（Aim #2）。这项拟议的研究将支持描述MK2信号传导对单核细胞迁移到局部牙周病感染部位并进一步分化为巨噬细胞和破骨细胞的影响。

DESCRIPTION (provided by applicant): Approximately 50% of Americans, age 30 and over, have periodontal disease. As periodontal disease progresses, inflammation can ultimately lead to irreversible bone and tooth loss. Mitogen-activated protein kinases (MAPKs) modulate the innate host inflammatory response during periodontal disease. Mitogen- activated protein kinase-activated protein kinase 2 (MK2), a downstream target of p38 MAPK, regulates inflammation in macrophages in aggressive periodontal disease animal models. Both macrophages and osteoclasts are derived from a monocyte lineage that expresses surface chemokine receptors critical for chemotaxis from circulation to peripheral sites of infection. Previous results from our project laboratory show that A. actinomycetemcomitans, an aggressive periodontal disease pathogen, and A. actinomycetemcomitans lipopolysaccharide (LPS) activate MK2. In an A. actinomycetemcomitans LPS-driven rat model, MK2 positively regulates inflammatory infiltration and bone loss. Preliminary data support a role for MK2 as a regulator of CXCR4 cell surface expression on CD11bhi-expressing cells, suggesting modulation of chemokine receptor expression may be an important mechanism of decreasing macrophage infiltrates under MK2 inhibition. MK2 signaling is critical for pathologic osteoclastogenesis, as supported by a decrease in LPS-driven osteoclast formation in Mk2-/- CD11blo osteoclast progenitor cells (OCPs) compared to Mk2+/+ (WT). In vivo, MK2 signaling was also critical for A. actinomycetemcomitans-induced bone loss in a murine calvarial model. These data support our hypothesis that MK2 signaling is required for monocyte chemotaxis and subsequent differentiation into macrophages and osteoclasts during host-pathogen interactions. To address the hypothesis, we will use bone marrow transplant to create MK2 chimeric animals followed by an "air pouch model" to assess the role of hematopoietic MK2 signaling in monocyte chemotaxis under A. actinomycetemcomitans challenge (Aim #1). The mechanism of MK2 signaling in A. actinomycetemcomitans- induced osteoclastogenesis with regards to NFATc1, the master transcription factor of osteoclastogenesis, will be studied in vitro using OCPs. The murine calvarial bone loss model will be used to confirm that MK2 is critical for A. actinomycetemcomitans driven osteoclastogenesis in vivo (Aim #2). This proposed research will support delineation of the impact of MK2 signaling on monocyte migration to the site of local periodontal disease infection and further differentiation into macrophages and osteoclasts.