Herpes simplex virus vector-mediated expression of interleukin-10 reduces below-level central neuropathic pain after spinal cord injury.

Background. Neuroimmune activation in the spinal dorsal horn plays an important role in the pathogenesis of chronic pain after peripheral nerve injury. Objective. The aim of this study was to examine the role of neuroimmune activation in below-level neuropathic pain after traumatic spinal cord injury (SCI). Methods. Right hemilateral SCI was created in male Sprague–Dawley rats by controlled blunt impact through a T12 laminectomy. Pain-related behaviors were assessed using both evoked reflex responses and an operant conflict-avoidance test. Neuroimmune activation was blocked by the anti-inflammatory cytokine interleukin-10 (IL-10) delivered by a nonreplicating herpes simplex virus (HSV)–based gene transfer vector (vIL10). Markers of neuroimmune activation were assessed using immunohistochemistry and Western blot. Results. One week after SCI, injured animals demonstrated mechanical allodynia, thermal hyperalgesia, and mechanical hyperalgesia in the hind limbs below the level of injury. Animals inoculated wi...