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Novel roles for articular cartilage vesicles in osteoarthritis

关节软骨囊泡在骨关节炎中的新作用

基本信息

批准号：
8597380
负责人：
Ann K Rosenthal
金额：
--
依托单位：
CLEMENT J. ZABLOCKI VA MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-10-01 至 2014-09-30
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Articular cartilage matrix vesicles (ACVs) are small membrane-bound extracellular organelles found in normal cartilage and chondrocyte cultures. To date, they have almost exclusively been described in reference to their role in pathologic matrix mineralization in articular cartilage. Yet, their presence in normal cartilage and roles for ACVs other than mineral formation remain unexplored. We recently demonstrated that ACVs contain functional RNA and are able to transfer labeled RNA and protein to naove chondrocytes. The addition of 1-10 5g/ml normal ACVs to normal chondrocyte monolayers increased markers characteristic of the hypertrophic chondrocytes seen in osteoarthritic (OA) cartilage. These exciting findings suggest that ACVs directly interact with chondrocytes and may participate in the cellular changes seen in OA. Preliminary data suggest an important role for proteoglycans in binding ACVs to pericellular matrix. We hypothesize that increased activity of proteoglycan-degrading enzymes in early OA promotes ACV "mobility" and fosters ACV-chondrocyte interactions in cartilage. However, the mechanisms through which ACVs bind to matrix components and the identity of the factors modulating matrix binding are unstudied. Similarly, little is known about the factors that mediate the cellular effects of ACVs. Exposure of normal articular chondrocytes to exogenous transglutaminase (Tgase) enzymes promotes chondrocyte hypertrophy in an integrin-dependent manner. As Tgases are present in high levels in ACVs, we hypothesize that Tgases in or on ACVs are responsible for inducing the hypertrophic phenotype in chondrocytes exposed to ACVs and that this effect is integrin-dependent. Using porcine ACV and chondrocytes, and replicating key experiments with ACVs from purchased human chondrocytes, we will investigate the following hypotheses: Specific aim 1: To investigate the hypothesis that ACVs bind to proteoglycans in matrix and ADAMTS4 and 5 release ACVs from cartilage matrix. Specific aim 2: To investigate the hypothesis that Tgases in ACVs are responsible for induction of the hypertrophic phenotype seen in chondrocytes after ACV exposure and that this is integrin-dependent. The ultimate goal of this work is to understand the role of ACVs in cartilage in the hope that manipulating the contents or availability of these organelles might contribute to the treatment of OA. PUBLIC HEALTH RELEVANCE: Narrative: Osteoarthritis is the most common form of arthritis in adults and affects 40 million Americans. It is currently untreatable, and often results in significant loss of independence and increased medical costs for affected people. Risk factors for OA, including advanced age, prior trauma, and obesity are particularly prevalent in the US veteran population and OA is a leading source of disability in veterans. This proposal deals with the role of small extracellular vesicles, called articular cartilage vesicles (ACVs) in OA. ACVs carry RNA and protein that can be transferred to chondrocytes. Transfer of ACV contents to chondrocytes mimics changes seen in OA. Understanding the role of ACVs in cartilage and ultimately manipulating the contents of ACVs could lead to novel therapies for OA.

描述（由申请人提供）：关节软骨基质囊泡（ACV）是正常软骨和软骨细胞培养物中发现的小型膜结合细胞外细胞器。迄今为止，它们几乎完全是根据它们在关节软骨病理基质矿化中的作用来描述的。然而，它们在正常软骨中的存在以及除了矿物质形成之外对 ACV 的作用仍有待探索。我们最近证明，ACV 含有功能性 RNA，并且能够将标记的 RNA 和蛋白质转移到幼稚软骨细胞中。在正常软骨细胞单层中添加 1-10 个 5g/ml 正常 ACV 会增加骨关节炎 (OA) 软骨中肥大软骨细胞的特征标记。这些令人兴奋的发现表明，ACV 直接与软骨细胞相互作用，并可能参与 OA 中观察到的细胞变化。初步数据表明，蛋白多糖在 ACV 与细胞周基质的结合中发挥着重要作用。我们假设早期 OA 中蛋白多糖降解酶活性的增加促进了 ACV 的“流动性”并促进了 ACV 与软骨细胞在软骨中的相互作用。然而，ACV 与基质成分结合的机制以及调节基质结合的因素的身份尚未研究。同样，人们对调节 ACV 细胞效应的因素知之甚少。正常关节软骨细胞暴露于外源性转谷氨酰胺酶（Tgase）酶会以整合素依赖性方式促进软骨细胞肥大。由于 Tgases 在 ACV 中存在高水平，我们假设 ACV 中或上的 Tgases 负责诱导暴露于 ACV 的软骨细胞的肥大表型，并且这种效应是整合素依赖性的。使用猪 ACV 和软骨细胞，并使用购买的人软骨细胞中的 ACV 重复关键实验，我们将研究以下假设：具体目标 1：研究 ACV 与基质中的蛋白聚糖结合以及 ADAMTS4 和 5 从软骨基质中释放 ACV 的假设。具体目标 2：研究以下假设：ACV 中的 Tgases 负责诱导 ACV 暴露后软骨细胞中出现的肥大表型，并且这是整合素依赖性的。这项工作的最终目标是了解 ACV 在软骨中的作用，希望操纵这些细胞器的内容或可用性可能有助于 OA 的治疗。公共卫生相关性：叙述：骨关节炎是成人最常见的关节炎形式，影响着 4000 万美国人。目前该病无法治疗，并且常常导致受影响者严重丧失独立性并增加医疗费用。骨关节炎的危险因素，包括高龄、既往创伤和肥胖，在美国退伍军人群体中尤其普遍，骨关节炎是退伍军人残疾的主要原因。该提案涉及小细胞外囊泡（称为关节软骨囊泡 (ACV)）在 OA 中的作用。 ACV 携带可转移至软骨细胞的 RNA 和蛋白质。 ACV 内容物向软骨细胞的转移模拟了 OA 中观察到的变化。了解 ACV 在软骨中的作用并最终操纵 ACV 的内容可能会导致 OA 的新疗法。