Phlpp phosphatases in osteoarthritis

摘要 骨关节炎（OA）是一种慢性疼痛性疾病，也是世界各地残疾的主要原因。OA是 其特征在于关节软骨退化和其他关节病变，包括半月板和韧带 损伤、滑膜炎、骨刺和关节疼痛。目前批准的治疗方法都不能改变疾病 通过减缓关节软骨退化或修复关节组织损伤来改善关节炎的进展。我们确认了菲利普的身份 磷酸酶作为软骨再生和关节疼痛的可修饰靶点。Phlpp 1和Phlpp 2是 在人OA软骨中异常表达。Phlpp 1敲除（KO）小鼠免受软骨损伤 退化和疼痛相关的行为（异常性疼痛和活动减少）手术后，不稳定的 内侧半月板（DMM），但Phlpp 1在仅表达聚集蛋白聚糖（Agc）的小鼠中条件性缺失 细胞（Phlpp 1 CKOAgc）仅被保护免于软骨降解，而不降低移动性。这些结果 表明Phlpp 1在软骨细胞中内在作用，以及Phlpp 1/2在其它组织或细胞中的作用 在铰接关节内。有趣的是，Phlpp 1和Phlpp 2的小分子抑制剂进一步减缓软骨 在Phlpp 1 CKOAgc小鼠中降解并增加移动性。Phlpp 1/2抑制剂也刺激软骨细胞 增殖和基质的产生，并阻止神经突生长和感觉神经元基因的表达， 体外和体内。总之，这些数据表明，体内多种细胞类型/组织中的Phlpp 1/2活性 关节连接关节有助于OA发病机制，Phlpp 2可能通过以下方式促进OA表型： 补偿软骨中Phlpp 1的缺乏和/或通过调节关节神经支配和疼痛相关的 行为。本项目的总体目标是确定Phlpp 1和Phlpp 2如何调节软骨数量 和质量（即硬度）以及Phlpp 1/2失活如何有助于损伤诱导的神经支配。具体 目的是：1）阐明Phlpp 1和Phlpp 2在关节损伤后关节软骨细胞中的作用，2） 确定Phlpp 1和Phlpp 2如何影响关节软骨的生物力学和结构特性， 损伤后和整个衰老过程中的其他关节组织，以及3）确定感觉神经元中Phlpp 1/2的活性 和OA相关的疼痛行为。这些研究将提供关于以下关系的新信息： 关节损伤、关节神经支配和疼痛。这种见解将使急需的疾病的发展- 治疗骨关节炎的药物

ABSTRACT Osteoarthritis (OA) is a chronically painful condition and a leading cause of disability around the world. OA is characterized by articular cartilage deterioration and other joint pathologies including meniscus and ligament damage, synovitis, bone spurs and joint pain. None of the currently approved treatments alter disease progression by slowing articular cartilage degradation or repairing damage to joint tissues. We identified Phlpp phosphatases as modifiable targets for cartilage regeneration and joint pain. Phlpp1 and Phlpp2 are abnormally expressed in human OA cartilage. Phlpp1 knockout (KO) mice are protected from cartilage degradation and pain-related behaviors (allodynia and reduced mobility) after surgery that destabilizes the medial meniscus (DMM), but mice where Phlpp1 is conditionally depleted in just aggrecan (Agc)-expressing cells (Phlpp1 CKOAgc) are only protected from cartilage degradation, not reduced mobility. These results indicate an intrinsic role for Phlpp1 in chondrocytes, as well as a role for Phlpp1/2 in other tissues or cells within articulating joints. Of interest, small molecule inhibitors of Phlpp1 and Phlpp2 further slow cartilage degradation in Phlpp1 CKOAgc mice and increase mobility. Phlpp1/2 inhibitors also stimulate chondrocyte proliferation and matrix production and prevent neurite outgrowth and expression of sensory neuron genes in vitro and in vivo. Together these data indicate that Phlpp1/2 activity in multiple cell types/tissues within articulating joints contributes to OA pathogenesis and that Phlpp2 may contribute to OA phenotypes by compensating for Phlpp1 deficiency in cartilage and/or by regulating joint innervation and pain-related behaviors. The overall goals of this project are to define how Phlpp1 and Phlpp2 modulate cartilage quantity and quality (i.e. stiffness) and how Phlpp1/2 inactivation contributes to injury-induced innervation. The specific aims are to: 1) Elucidate the roles of Phlpp1 and Phlpp2 in articular chondrocytes following a joint injury, 2) Determine how Phlpp1 and Phlpp2 affect biomechanical and structural properties of articular cartilage and other joint tissues after injury and throughout aging, and 3) Define activities of Phlpp1/2 in sensory neurons and OA-associated pain behaviors. These studies will provide new information about the relationship between joint damage, joint innervation and pain. Such insights will enable the development of much needed disease- modifying drugs for osteoarthritis.