T CELLS AND PTH INDUCED BONE LOSS

T 细胞和 PTH 诱导的骨丢失

• 批准号: 7883442
• 负责人: ROBERTO PACIFICI
• 金额: $ 31.91万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-24 至 2012-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7883442
• 关键词: Binding; Bone Diseases; Bone Marrow; Cell Count; Cells; End stage renal failure; Fracture; Goals; Hyperparathyroidism; Interleukin-1; Investigation; Lead; Mediating; Membrane; Mus; Osteoclasts; Osteoporosis; Phenotype; Production; Public Health; Risk Factors; Role; Signal Transduction; Stromal Cells; T-Lymphocyte; T-Lymphocyte Subsets; TNF gene; TNFSF11 gene; TNFSF5 gene; bone; bone loss; bone turnover; cytokine; in vitro Model; in vivo; insight; new therapeutic target; prevent; receptor; response

DESCRIPTION (provided by applicant): Primary hyperparathyroidism (PHP) is a common cause of accelerated bone loss and osteoporosis. In spite of extensive investigation the mechanism of the bone catabolic action of PTH has not been not been completely elucidated. PHP is also an important cause of increased bone turnover, which is an independent risk factor for fractures. Studies in 4 in vivo and 5 in vitro models suggest that T cells provide survival, proliferative and pro-osteoclastogenic signals to bone marrow (BM) stromal cells (SCs) through the membrane-bound costimulatory molecule CD40L. As a result, T cell deficient mice are protected against PTH induced bone loss. This is due to the fact that BM SCs derived from T cell deficient mice are fewer in number, produce lower amounts of osteoclastogenic cytokines, and lack the capacity to support PTH induced osteoclast (OC) formation. The capacity of T cells to upregulate both the number and the osteoclastogenic activity of SCs is abolished by silencing of the PTH receptor PPR in T cells. We thus hypothesize that PTH directly stimulates T cells to promote SC osteoclastogenic activity by signaling through the PTH receptor PPR, and that T cells regulate SC number and activity through CD40L. The goal of this application is to determine the mechanism by which T cells mediate the bone catabolic activity of PTH. In Specific Aim 1 we will determine the phenotype of the T lymphocytes which are regulated by PTH, and mediate PTH induced bone loss. This will be accomplished by evaluating the effect of continuous PTH treatment in mice lacking specific T cell subsets. In Aim 2 we will determine the role of direct PPR signaling in T cells in PTH induced OC formation and bone loss. This will be accomplished by utilizing T cells from conditional KO mice which lack the PTH receptor in T cells. We will also determine if PPR signaling in T cells stimulate OC formation by generating T cell signals which upregulate the osteoclastogenic activity of SCs, and if PPR signaling in T cells increases their production of RANKL, TNF and IL-1, and their expression of CD40L. In Aim 3 we will determine if the capacity to regulate SC osteoclastogenic activity in a spontaneous fashion (as opposed to in response to PTH stimulation) and if in vivo silencing of CD40L prevent the increase in SC osteoclastogenic activity, OC formation and bone loss induced by PTH. The discovery of new mechanisms of action of PTH is relevant to public health as it may lead to the identification of novel therapeutic targets for PHP, osteoporosis and the bone disease associated with end stage renal disease. Our studies may also provide insights on strategies for augmenting the anabolic activity of intermittent PTH treatment. One such strategy could be that of antagonizing T cell production of osteoclastogenic factors.

描述（由申请人提供）：原发性甲状旁腺功能亢进（PHP）是加速骨质流失和骨质疏松症的常见原因。尽管进行了广泛的研究，但尚未完全阐明PTH骨分解代谢作用的机制。 PHP也是增加骨骼更新的重要原因，这是骨折的独立危险因素。在4个体内和5个体外模型中进行的研究表明，T细胞通过膜结合的共刺激分子CD40L向骨髓（BM）基质细胞（SC）提供生存，增殖和促层型碎屑信号。结果，T细胞缺乏小鼠受到PTH诱导的骨质流失的保护。这是由于以下事实：源自T细胞缺乏小鼠的BM SC的数量较少，产生较低量的破骨细胞源性细胞因子，并且缺乏支持PTH诱导的破骨细胞（OC）形成的能力。 T细胞在T细胞中的PTH受体PPR沉默消除了T细胞上调SC的数量和破骨构成活性的能力。因此，我们假设PTH直接刺激T细胞通过通过PTH受体PPR信号传导来促进SC破骨细胞生成活性，并且T细胞通过CD40L调节SC数量和活性。该应用的目的是确定T细胞介导PTH骨分解代谢活性的机制。在特定目标1中，我们将确定受PTH调节的T淋巴细胞的表型，并介导PTH诱导的骨质流失。这将通过评估缺乏特定T细胞亚群的小鼠的连续PTH治疗的影响来实现。在AIM 2中，我们将确定直接PPR信号在T细胞中PTH诱导的OC形成和骨质流失中的作用。这将通过利用来自T细胞中缺乏PTH受体的条件KO小鼠的T细胞来实现。我们还将确定T细胞中的PPR信号是否通过产生上调SCS的破骨细胞生成活性的T细胞信号来刺激OC的形成，以及T细胞中的PPR信号是否会增加其RANKL，TNF和IL-1的产生，以及CD40L的表达。在AIM 3中，我们将确定以自发的方式调节SC破骨细胞生成活性的能力（而不是响应PTH刺激），以及CD40L的体内沉默是否可以阻止SC骨化层析活性的增加，OC形成和PTH诱导的OC形成和骨骼损失。发现新的PTH作用机理与公共卫生有关，因为它可能导致鉴定出针对PHP，骨质疏松症的新型治疗靶标和与终阶段肾脏疾病有关的骨骼疾病。我们的研究还可以提供有关增强间歇性PTH治疗合成代谢活性的策略的见解。一种这样的策略可能是拮抗骨细胞生成因子的T细胞产生。