Treating knee osteoarthritis by sPLA2 inhibitor-loaded micellar nanoparticles

摘要 膝关节骨关节炎（OA）是一种疼痛和使人衰弱的关节疾病，可导致关节疼痛、关节功能丧失和对日常生活质量的有害影响。尽管最近在药物开发方面取得了进展，但没有疾病修饰药物可用于延迟OA进展或逆转疾病。美国每年进行超过60万例膝关节置换术。许多临床前和临床研究表明，各种炎症介质参与了OA的发病机制。尽管炎症和OA之间存在很强的相关性，但一个主要的挑战是如何解决炎症状态，因为常见的抗炎药物已证明对减缓或逆转OA进展的效用有限。此外，快速关节清除和对无血管软骨组织的渗透性差进一步限制了许多有前途的OA药物的临床应用。因此，仍然迫切需要确定新的治疗靶点并开发用于OA患者的有效药物递送系统。分泌型磷脂酶A2（sPLA 2）酶特异性水解磷脂的sn-2酯键，释放游离脂肪酸和溶血磷脂。这些产物是许多慢性炎性疾病中众所周知的上游炎症介质。然而，很少有研究探讨sPLA 2在OA中的作用以及sPLA 2上调与OA进展之间的因果关系。我们最近的研究发现，sPLA 2水平在来自人类患者和OA动物模型的全层关节软骨中急剧增加。探索靶向sPLA 2通路的可能性（即通过sPLA 2抑制剂，sPLA 2 i）用于OA治疗并克服关节内小sPLA 2 i递送的挑战（即快速清除和软骨渗透差），我们工程化sPLA 2 i载硫醚酰胺-PC磷脂胶束纳米粒（硫醚酰胺-NPs），并提供了硫醚酰胺-NPs而不是游离sPLA 2 i可以有效减少关节炎症的第一个证据，减轻关节疼痛和预防小鼠OA模型中的OA进展。虽然这些数据是有希望的，但硫醚酰胺-PC不是临床批准的药物，并且具有相当差的IC 50（~2 μM）。本提案的总体目标是使用经临床测试且更有效的sPLA，i伐瑞拉迪（IC 50比硫醚酰胺-PC低约210倍）来构建sPLA 2响应性伐瑞拉迪-NP，并在临床相关动物模型中测试其疗效。我们相信，拟议的工作将导致临床可翻译的纳米技术，可以改变膝关节OA的护理标准。该提案的具体目的是1）合成和优化sPLA 2-应答伐瑞拉迪-NP; 2）评价伐瑞拉迪-NP在损伤诱导的小鼠OA模型中的疗效; 3）评价伐瑞拉迪-NP在豚鼠自发性OA模型中的疗效。

ABSTRACT Knee osteoarthritis (OA) is a painful and debilitating joint disease that can result in joint pain, loss of joint function, and deleterious effects on the quality of daily life. Despite recent advances in drug development, there is no disease-modifying drug available to delay OA progression or reverse the disease. Over 600,000 knee replacements are performed each year in the US. Many preclinical and clinical studies have revealed that various inflammatory mediators have been implicated in OA pathogenesis. Despite the strong association between inflammation and OA, a major challenge is how to resolve the inflammatory state since common anti-inflammatory drugs have demonstrated limited utility to slow or reverse OA progression. Moreover, rapid joint clearance and poor penetration into avascular cartilage tissues further limit the clinical application of many promising OA drugs. Therefore, there remains a critical need to identify new therapeutic targets and to develop effective drug delivery systems for OA patients. Secreted phospholipase A2 (sPLA2) enzyme specifically hydrolyzes the sn-2 ester bond of phospholipids, releasing free fatty acids and lysophospholipids. These products are well-known upstream inflammation mediators in many chronic inflammatory diseases. However, few studies have explored the role of sPLA2 in OA and the cause-effect relationship between sPLA2 upregulation and OA progression. Our recent studies found that sPLA2 level is drastically increased in full-thickness articular cartilage from both human patients and animal models of OA. To explore the potential of targeting sPLA2 pathway (i.e. by sPLA2 inhibitor, sPLA2i) for OA treatment and overcome the challenges of small sPLA2i delivery within joints (i.e. rapid clearance and poor cartilage penetration), we engineered sPLA2i (thioetheramide-PC)-loaded phospholipid micellar nanoparticles (thioetheramide-NPs) and provided the first evidence that thioetheramide-NPs, but not free sPLA2i, can effectively reduce joint inflammation, alleviate join pain and prevent OA progression in a mouse OA model. While these data are promising, thioetheramide-PC is not a clinically-approved drug and has a rather poor IC50 (~2 μM). The overall goal of this proposal is to use a clinically tested and more potent sPLA,i varespladib (~210-fold lower IC50 than thioetheramide-PC) to construct sPLA2-responsive varespladib-NPs and test their efficacy in clinically relevant animal models. We believe the proposed work will result in a clinically translatable nanotechnology that could alter the standard of care for knee OA. The specific aims for the proposal are 1) synthesize and optimize sPLA2-responsive varespladib-NPs; 2) evaluate the efficacy of varespladib-NPs in injury-induced mouse OA models; and 3) evaluate the efficacy of varespladib-NPs in the guinea pig model of spontaneous OA.