578. Suppression of Inflammation Following Intramuscular Administration of Pseudotyped AAV-TNFR:Fc Vectors in a Rat Model of Arthritis

Abstract

TNF-|[alpha]| antagonists such as anti-TNF-|[alpha]| monoclonal antibodies or soluble tumor necrosis factor receptor have proven to be useful therapeutics for the treatment of autoimmune inflammatory diseases including rheumatoid and psoriatic arthritis. In the current study, we employed a monoarticular arthritis model in rats that allowed us to evaluate the long-term effect of TNFR:Fc expression on recurrence of joint inflammation. Monoarticular arthritis was initiated by injection of a small dose of peptidoglycan-polysaccharide polymers (PG-APS) isolated from cell walls of group A streptocci into the hind ankle joint. This resulted in a flare of inflammation that resolved within five days. Intramuscular administration of AAV-TNFR:Fc vectors performed on day seven. To assess the long-term effect of TNFR:Fc expressions on suppression of arthritis in this model, animals were evaluated for four rounds of remission and reactivation of joint inflammation. Reactivation of joint inflammation was induced by intravenous injection of PG-APS. Animals that were treated with vehicle, 109, 5x109 DRP of AAV2/1-TNFR:Fc or 1012 DRP of AAV2-TNFR:Fc developed a significant flare of inflammation in their ankle joints. In these animals, levels of TNFR:Fc protein in the circulation were below 0.75 |[mu]|g/mL. In contrast, when animals were treated with 1010, 1011or 1012 DRP of AAV2/1-TNFR:Fc, levels of TNFR:Fc protein in the circulation were 1.27|[ndash]|8.35 |[mu]|g/mL, 6.8|[ndash]|27.4 |[mu]|g/mL and 19.6|[ndash]|61 |[mu]|g/mL, respectively. The inflammatory response in these animals, as measured by joint volume, was completely suppressed. To increase the transduction efficiency of AAV2/2- TNFR:Fc following administration of 1012 DRP, we employed treatment with proteosome inhibitor that has been shown to enhance AAV transduction. In these animals, levels of TNFR:Fc protein in the circulation increased up to 3.65 |[mu]|g/mL, and led to significant decrease in joint inflammation.