Mechanobiological Mechanism for Inflammaory Bone Loss

描述（由申请人提供）：目前的治疗药物，如双膦酸盐或合成代谢药物，并不总是有效地预防或治疗骨质疏松症和风湿性关节炎、牙周炎和种植体松动引起的炎症性骨质流失。因此，开发有效的治疗方法来保护骨骼存在障碍。在为期4年的父母资助奖励期间（2007-2011），我们在描述炎症性骨溶解背景下的NFATc1和pERK1/2等分子通路方面取得了重大进展。为了将我们的发现转化为临床前研究，我们筛选了几种候选药物，并确定PTH（1-34）是一种新型抗炎药。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，旨在揭示PTH（1-34）在炎症性破骨细胞发生和骨溶解的背景下的抗炎功能。脂多糖与骨感染和种植体相关的骨质流失有关。LPS已被广泛用于建立一种新的治疗理念。当PTH（1-34）局部递送时，我们观察到PTH（1-34）在体内出人意料地抑制了lps诱导的破骨细胞生成。随后的实验对这一现象进行了研究。我们观察到PTH（1-34）不通过破骨细胞前体抑制RANKL，但在成骨细胞中抑制促破骨细胞因子如MCSF。LPS诱导的ERK1/2磷酸化，一种常见的炎性骨溶解信号传感器，也通过LPS处理被抑制。我们优化了PTH（1-34）的剂量和给药方法。因此，我们提出了一种治疗上的创新假设，即局部给予低剂量PTH（1- 34）通过抑制成骨谱系细胞中破骨细胞因子的产生来抑制炎症性骨质流失。我们试图通过两个平行的目标来研究这一假设，并最终建立PTH的一种新的抗破骨细胞功能（1-34）。在Specific Aim 1中，我们将建立PTH（1-34）在体内骨溶解中的新型抗炎作用。我们将

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.