Principal Investigator: Alan Nixon

DESCRIPTION (provided by applicant): 

Joint trauma and subsequent osteoarthritis (OA) remain significant injuries in racehorses and the aging human population.  The consequences of articular impact trauma extend beyond the precipitation of OA to include predisposition to fracture breakdown.  There are no treatments that markedly alter the progression of OA, and symptomatic relief through medical therapy provides only transitory improvement in function. Development of more prolonged and even joint stabilizing therapies have emerged from regenerative medicine. The broad objectives of this proposal are to test a dual effector approach for control of joint disease. Our previous Zweig Study (2016) allowed us to clone and develop vectorized lubricin (PRG4), a vitally important joint medication - the “new” HA, and interlukin-1 receptor antagonist (IL-1Ra aka IRAP), a competitive receptor inhibitor for interleukin-1 (the messenger of destruction in joint disease). We then tested each alone and in combination to determine how each component influenced cytokine and lubricin abundance. The current proposal develops and evaluates a single AAV vector carrying both transgenes. We expect this will initiate an additive or synergistic approach to OA control, by stimulating joint repair with enhanced lubricin formation and limiting degradation through concurrent IL-1Ra synthesis.  We hypothesize that the concurrent expression of lubricin and IL-1Ra will have a more profound effect on limiting arthritis than either construct used alone.  We have previously determined the biophysical organization of lubricin on articular cartilage, the partnering role of the galectins, and the levels and location of lubricin in joint trauma and osteoarthritis. These studies indicate that lubricin protects articular cartilage from fibrillation by functioning as a boundary lubricant and is further concentrated in the damaged surface layer of cartilage in an effort to protect from deeper fibrillation.  We seek to enhance this lubricin layer through gene induced synthesis, and to limit further cartilage malacia by limiting the principal degradative cytokine, interleukin-1.  Data in rodent models supports the use of lubricin gene delivery as an intra-articular therapy for the prevention and treatment of post-traumatic OA. However, evidence to support the use of lubricin in a larger translational model is lacking, and no information is available on using a combination of lubricin and IL-1Ra.  Both aspects are appealing in controlling OA.  This proposal will test the hypothesis by two specific aims. Specific Aim 1. Develop a combinatorial AAV gene construct co-expressing lubricin and IL-1Ra. Aim 2. Evaluate the OA attenuating effects of gene enhanced lubricin synthesis, with and without IL-1Ra synthesis, after intraarticular injection of the coding genes.  The equine carpal fragmentation model will be used. Unlike many other in vivo models, no instability is created, and the model induces progressive OA without severe lameness.  This in vivo study will determine the efficacy of intra-articular dual axis lubricin and IL-1Ra therapy in a large animal model of OA. This may be the next generation biological approach to control equine joint disease. It is a non-pharmaceutical product that holds promise of a sustained-action regenerative approach to limit the symptoms and progression of joint trauma and OA.