High cerebrospinal fluid levels of interleukin-10 attained by AAV in dogs

Intrathecal ( IT) gene transfer using adeno-associated virus ( AAV) may be clinically promising as a treatment for chronic pain if it can produce sufficiently high levels of a transgene product in the cerebrospinal fluid ( CSF). Although this strategy was developed in rodents, no studies investigating CSF levels of an analgesic or antiallodynic protein delivered by IT AAV have been performed in large animals. Interleukin-10 ( IL-10) is an antiallodynic cytokine for which target therapeutic levels have been established in rats. The present study tested IT AAV8 encoding either human IL-10 ( hIL-10) or enhanced green fluorescent protein ( EGFP) in a dog model of IT drug delivery. AAV8/hIL-10 at a dose of 3.5 x 10(12) genome copies induced high hIL-10 levels in the CSF, exceeding the target concentration previously found to be antiallodynic in rodents by 41000-fold. AAV8/EGFP targeted the primary sensory and motor neurons and the meninges. hIL-10, a xenogeneic protein in dogs, induced anti-hIL-10 antibodies detectable in the CSF and serum of dogs. The high hIL-10 levels demonstrate the efficacy of AAV for delivery of secreted transgenes into the IT space of large animals, suggesting a strong case for further development toward clinical testing.