title: Humoral and cell-mediated immune response, and growth factor synthesis after direct intraarticular injection of rAAV2-IGF-I and rAAV5-IGF-I in the equine middle carpal joint.
abstract: Intraarticular (IA) administration of viral vectors expressing a therapeutic transgene is an attractive treatment modality for osteoarthritis (OA) as the joint can be treated as a contained unit. Humoral and cell-mediated immune responses in vivo can limit vector effectiveness. Transduction of articular tissues has been investigated; however, the immune response to IA vectors remains largely unknown. We hypothesized that IA rAAV2 and rAAV5 overexpressing insulin-like growth factor-I (IGF-I) would result in long-term IGF-I formation but would also induce neutralizing antibodies (NAb) and anti-capsid effector T cells. Twelve healthy horses were assigned to treatment (rAAV2 or rAAV5) or control (saline) groups. Middle carpal joints were injected with 5×10(11) vector genomes/joint. Synovial fluid was analyzed for changes in composition, NAb titers, immunoglobulin isotypes, proinflammatory cytokines, and IGF-I. Serum was analyzed for antibody titers and cytokines. A T cell restimulation assay was used to assess T cell responses. Injection of rAAV2- or rAAV5-IGF-I did not induce greater inflammation compared with saline. Synovial fluid IGF-I was significantly increased in both rAAV2- and rAAV5-IGF-I joints by day 14 and remained elevated until day 56; however, rAAV5 achieved the highest concentrations. A capsid-specific T cell response was not noted although all virus-treated horses had increased NAbs in serum and synovial fluid after treatment. Taken together, our data show that IA injection of rAAV2- or rAAV5-IGF-I does not incite a clinically detectable inflammatory or cell-mediated immune response and that IA gene therapy using minimally immunogenic vectors represents a clinically relevant tool for treating articular disorders including OA.
authors.affiliation: 1 Department of Clinical Sciences, Cornell University College of Veterinary Medicine , Ithaca, NY 14853.
authors.forename: Kyla
authors.initials: K
authors.lastname: Ortved
authors.forename: Bettina
authors.initials: B
authors.lastname: Wagner
authors.forename: Roberto
authors.initials: R
authors.lastname: Calcedo
authors.forename: James
authors.initials: J
authors.lastname: Wilson
authors.forename: Deanna
authors.initials: D
authors.lastname: Schaefer
authors.forename: Alan
authors.initials: A
authors.lastname: Nixon
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology; D050824:Carpal Joints / Q000276:immunology*; D000229:Dependovirus; D005822:Genetic Vectors / Q000008:administration & dosage / Q000494:pharmacology*; D006736:Horses; D007111:Immunity, Cellular / Q000187:drug effects*; D056724:Immunity, Humoral / Q000187:drug effects*; D007132:Immunoglobulin Isotypes / Q000276:immunology; D007270:Injections, Intra-Articular; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis*; D060888:Real-Time Polymerase Chain Reaction; D013056:Spectrophotometry, Ultraviolet; D018709:Statistics, Nonparametric; D013583:Synovial Membrane / Q000737:chemistry
chemical_list: D057134:Antibodies, Neutralizing; D007132:Immunoglobulin Isotypes; D036341:Intercellular Signaling Peptides and Proteins; D007334:Insulin-Like Growth Factor I