Mechanobiological Mechanism for Inflammaory Bone Loss

描述(申请人提供)：目前的治疗方法，如双磷酸盐或合成代谢药，并不总是有效地预防或治疗类风湿性关节炎、牙周炎和种植体松动引起的骨质疏松症和炎症性骨丢失。因此，开发有效的治疗方法来保存骨骼是一个障碍。在为期4年的父母资助获奖期间(2007-2011年)，我们在描述炎症骨溶解的分子通路方面取得了重大进展，如NFATc1和pERK1/2。为了将我们的发现转化到临床前领域，我们筛选了几种候选药物，并确定PTH(1-34)是一种新的抗炎药。现在，我们正在为我们的A1竞争性更新提案设定一个新的方向，试图解开甲状旁腺素(1-34)在炎性破骨细胞生成和骨溶解背景下的一种未知的抗炎功能。脂多糖与骨感染和种植体相关的骨丢失有关。脂多糖已被广泛用于建立一种新的治疗概念。当局部注射PTH(1-34)时，我们观察到PTH(1-34)在体内意外地抑制了脂多糖诱导的破骨细胞的生成。随后的实验被用来研究这一现象。我们观察到PTH(1-34)不是通过破骨细胞前体抑制RANKL，而是抑制成骨细胞中的前破骨细胞因子，如MCSF。LPS诱导的ERK1/2的磷酸化也被抑制。ERK1/2是一种常见的炎性骨溶解信号转导。我们为拟议的实验优化了甲状旁腺素(1-34)的剂量和给药方法。因此，我们提出了一个治疗创新假说，即局部应用小剂量甲状旁腺素(1-34)通过抑制成骨细胞中破骨细胞因子的产生来抑制炎症性骨丢失。我们试图通过两个平行的目标来研究这一假说，并最终建立一种新的甲状旁腺素(1-34)的抗破骨细胞功能。在特定的目标1，我们将建立一个新的抗炎作用的甲状旁腺素(1-34)的背景下，在体内的骨溶解。我们会 确定局部应用低剂量甲状旁腺素(1-34)水凝胶是否能防止临床相关刺激(如RANKL、脂多糖和髋关节模拟器产生的COCR磨损颗粒)引起的炎性骨溶解。破骨细胞生成将通过组织蛋白酶K光信号和破骨细胞计数来测量。动态骨组织形态计量学将使我们能够检查骨转换。在特定的目标2中，我们将确定PTH(1-34)在成骨细胞中显示抗炎作用的机制。我们将研究PERK/细胞因子表达与两条不同的PTH信号通路(Gs/腺苷环化酶/cAMP和GQ/11-磷脂酶C)之间的功能相互作用。我们将使用特定途径的类似物、体内的溶骨作用和体外巨噬细胞-成骨细胞共培养模型，进一步阐明每条途径的功能重要性。综上所述，我们将为基于水凝胶的低剂量甲状旁腺素在炎症骨溶解背景下的抗炎作用提供新的治疗和机制方面的见解，用于药物开发。

DESCRIPTION (provided by applicant): Current therapeutics such as bisphosphonates or anabolic agents do not always effectively prevent or treat osteoporosis and inflammatory bone loss in rheumatoid arthritis, periodontitis, and implant loosening. Therefore, there is a barrier t developing effective therapeutics to preserve bone. During the 4-year parent grant award period (2007-2011), we made significant progress in delineating molecular pathways such as NFATc1 and pERK1/2 in the context of inflammatory osteolysis. In order to translate our findings into a preclinical arena, we screened several drug candidates and identified PTH(1-34) as a novel anti-inflammatory agent. Now, we are setting a new direction for our A1 competitive renewal proposal that seeks to unravel, an as yet unknown, anti-inflammatory function of PTH(1-34) in the context of inflammatory osteoclastogenesis and osteolysis. LPS has been implicated in bone infection and implant-related bone loss. LPS has been commonly used to establish a new therapeutic concept. When PTH(1-34) was delivered topically, we observed that PTH(1-34) surprisingly inhibited LPS-induced osteoclastogenesis in vivo. Subsequent experiments were conducted to investigate this phenomenon. We observed that PTH(1-34) was not inhibiting RANKL through osteoclast precursors, but was inhibiting pro-osteoclastogenic cytokines like MCSF in osteoblast cells. LPS induced phosphorylation of ERK1/2, a common inflammatory osteolysis signal transducer, was also inhibited via LPS treatment. We have optimized PTH(1-34) doses and delivery methods for the proposed experiments. Therefore, we developed a therapeutically innovative hypothesis that regionally administered low-dose PTH(1- 34) inhibits inflammatory bone loss by suppressing osteoclastogenic cytokine production in osteogenic lineage cells. We seek to investigate this hypothesis through two parallel Aims and ultimately, establish a novel anti- osteoclastogenic function of PTH(1-34). In Specific Aim 1, we will establish a novel anti-inflammatory role of PTH(1-34) in the context of osteolysis in vivo. We will determine whether regionally applied low-dose PTH(1-34) in a hydrogel prevents inflammatory osteolysis in response to clinically relevant stimuli such as RANKL, LPS and hip joint simulator generated CoCr wear particles. Osteoclastogenesis will be measured by cathepsin K optical signals and by counting osteoclast numbers. Dynamic bone histomorphometry will enable us to examine bone turnover. In Specific Aim 2, we will define the mechanism by which PTH(1-34) exhibits an anti- inflammatory effect in osteoblasts. We will examine the functional interactions between pERK/cytokine expression and two diverging PTH signaling pathways (Gs/adenylate cyclase/cAMP and Gq/11-phospholipase C). We will further delineate the functional importance of each pathway using pathway-specific analogs, our in vivo osteolysis and in vitro macrophage-osteoprogenitor co-culture models. In summary, we will provide novel therapeutic and mechanistic insights into specific anti-inflammatory function of hydrogel-based delivery of low- dose PTH in the setting of inflammatory osteolysis for drug development.