HSV-mediated p55TNFSR reduces neuropathic pain induced by HIV gp120 in rats through CXCR4 activity

Human immunodeficiency virus (HIV)-related neuropathic pain is a debilitating chronic condition that is severe and unrelenting. Despite extensive research, the detailed neuropathological mechanisms remain unknown, which hinders our ability to develop effective treatments. In this study, we investigated the role of proinflammatory molecules, tumor necrosis factor-alpha (TNF alpha), CXCR4 and stromal-derived factor-1 alpha (SDF1 alpha), in the L4/5 dorsal root ganglia (DRG) and the spinal dorsal horn in HIV gp120 protein-mediated neuropathic pain. Our results showed that the application of HIV gp120 to the sciatic nerve induced upregulation of TNF alpha, CXCR4 and SDF1 alpha in both the DRG and the lumbar spinal dorsal horn. Non-replicating herpes simplex virus (HSV) vector encoding the p55INFSR gene and producing a TNF-soluble receptor (TNFSR) to block bioactivity of TNF alpha reversed mechanical allodynia. Intrathecal AMD3100 (CXCR4 antagonist) increased mechanical threshold. The HSV vectors expressing p55TNFSR reversed upregulation of TNF alpha, CXCR4 and SDF1a induced by gp120 in the DRG and the spinal dorsal horn. These studies suggest that proinflammatory TNF alpha to the CXCR4/SDF1 pathway has an important role in the HIV-related neuropathic pain state and that blocking the proinflammatory cytokines or chemokines is able to reduce neuropathic pain. This work provides a novel gene therapy proof-of-concept for HIV-associated neuropathic pain.