Utility of AAV Serotypes for Gene Delivery in Treatment of Chronic Joint Disease

描述（由申请人提供）：骨关节炎（OA）是一种无法治愈的慢性衰弱性疾病。有强有力的证据表明，白细胞介素-1 （IL-1）在骨性关节炎中充当软骨丢失、疼痛和炎症的关节内介质。其天然抑制剂IL-1受体拮抗剂（IL-1Ra）有望成为一种有效的治疗方法，但临床应用受到难以达到和维持关节内有效浓度的阻碍。我们致力于开发将IL-1Ra cDNA传递到关节包膜组织细胞的技术，使这些组织成为持续升高IL-1Ra产生的内源性位点。这种基于基因的方法消除了重复应用重组蛋白的需要，同时提供了最大浓度的基因产物，特别是在疾病部位。在小动物模型中，直接关节内注射某些重组病毒载体可以提供治疗性转基因的表达，其水平足以阻止关节炎。使用免疫相容的载体和cdna，外源性转基因可以在填充荚膜组织的细胞中无限表达。腺相关病毒（AAV）提供了许多优势，有利于其作为治疗关节炎的基因传递载体。双链（自互补[sc]）载体和替代衣壳血清型的发展克服了以往的不足，因此AAV可以被现实地视为人类OA应用的候选物。本研究将验证一种假设，即通过scAAV介导的IL-1Ra cDNA局部递送到OA关节将提供持续的治疗益处。马为研究关节疾病的关节内基因转移提供了一个独特的系统。他们的关节大小与人类的膝盖成正比，他们很容易患上OA。在具体目标1和2中，我们将通过在马关节中进行药代动力学研究，表征同源马IL-1Ra (eqIL-1Ra) cDNA传递后的生物分布和转基因表达模式，来确定scAAV作为人体关节基因传递系统的用途。从这部分研究中获得的经验教训将用于Specific Aim 3，以评估scAAV介导的eqIL-1Ra递送抑制马OA骨软骨碎裂模型病理的能力。通过在适当的规模和相关的疾病背景下以这种方式研究scAAV-IL-1Ra基因治疗的疗效，将出现其治疗能力的明确代表。如果成功，这些研究将提供必要的药代动力学、安全性和有效性数据，以支持人体试验的实施。

DESCRIPTION (provided by applicant): Osteoarthritis (OA) is chronic, debilitating condition for which there is no cure. There is strong evidence that interleukin-1 (IL-1) serves as an intra-articular mediator of cartilage loss, pain and inflammation in OA. Its natural inhibitor, the IL-1 receptor antagonist (IL-1Ra), holds promise as an effective treatment, but clinical application is hindered by difficulty achieving and maintaining effective concentrations intra-articularly. We have worked to develop technologies for delivering the cDNA for IL-1Ra to cells in the capsular tissues of joints, such that these tissues become endogenous sites of sustained, elevated IL-1Ra production. This gene-based approach removes the need for repeated application of the recombinant protein while providing the greatest concentration of the gene product specifically at the site of disease. Direct intra- articular injection of certain recombinant viral vectors can provide expression of therapeutic transgenes at levels sufficient to halt arthritis in small animal models. With the use of immunologically compatible vectors and cDNAs, exogenous transgenes can be expressed indefinitely in cells that populate the capsular tissues. Adeno-associated virus (AAV) offers many advantages that favor its use as a gene delivery vehicle for treatment of arthritis. The development of double-stranded (self-complementary [sc]) vectors and alternate capsid serotypes overcomes previous deficiencies such that AAV can be realistically considered as a candidate for human application in OA. The present study will test the hypothesis that scAAV- mediated delivery of the cDNA for IL-1Ra locally to joints with OA will provide sustained therapeutic benefit. Horses provide a unique system in which to study intra-articular gene transfer for joint disease. Their joints are proportional in size to human knees, and they are vulnerable to the onset of OA. In Specific Aims 1 and 2 we will work to determine the utility of scAAV as a gene delivery system to joints of human scale by performing pharmacokinetic studies in equine joints, characterizing biodistribution and transgenic expression patterns following delivery of the cDNA for the homologous equine IL-1Ra (eqIL-1Ra). Lessons learned from this part of the study will be used in Specific Aim 3 to evaluate the capacity of scAAV- mediated delivery of eqIL-1Ra to inhibit the pathologies of an osteochondral fragmentation model of OA in horses. By studying the efficacy of scAAV-IL-1Ra gene therapy in this manner- on an appropriate scale and in a relevant disease context- a clear representation of its therapeutic capacity will emerge. If successful these studies will provide the necessary pharmacokinetic, safety and efficacy data to support the implementation of human trials. PUBLIC HEALTH RELEVANCE: This study is designed to explore the usefulness of a local gene therapy for osteoarthritis. It involves the injection into the joint of recombinant viral vectors containing genes, whose products protect the cartilage from degeneration. To examine the usefulness of this procedure on a human scale, we will perform safety and efficacy studies in the forelimb joints of horses. These joints are proportional in size to human knees, and they naturally develop osteoarthritis. Information from these studies will be used to support clinical trials in humans.