Improvement of spinal non-viral IL-10 gene delivery by D-mannose as a transgene adjuvant to control chronic neuropathic pain

• Published in: Journal of neuroinflammation Vol. 11; no. 1; p. 92
• Main Authors: Dengler, Ellen C, Alberti, Lauren A, Bowman, Brandi N, Kerwin, Audra A, Wilkerson, Jenny L, Moezzi, Daniel R, Limanovich, Eugene, Wallace, James A, Milligan, Erin D
• Format: Journal Article
• Language: English
• Published: England BioMed Central 21-05-2014; BioMed Central Ltd
• Subjects: Addictive behaviors; Animals; Anti-Inflammatory Agents - therapeutic use; Behavior; Cell culture; Cells, Cultured; Chronic Disease; Colleges & universities; Constriction, Pathologic - complications; Cytokines; Cytokines - genetics; Cytokines - metabolism; Deoxyribonucleic acid; Dexamethasone - therapeutic use; Disease Models, Animal; DNA; Genes; Genetic Therapy; Genotype & phenotype; Health sciences; Interleukin-10 - biosynthesis; Interleukin-10 - therapeutic use; Kinases; Male; Mannose - therapeutic use; Medicine; Mice; Microphthalmos - drug therapy; Microphthalmos - metabolism; Nervous system; Neuralgia - etiology; Neuralgia - therapy; Neurosciences; Nitric oxide; Nitric Oxide - metabolism; Pain Threshold - physiology; Proteins; Rats; Rats, Sprague-Dawley; Spinal Cord - metabolism; Spinal Cord - physiology; Substance abuse treatment; Variance analysis
• ISSN: 1742-2094; 1742-2094
• DOI: 10.1186/1742-2094-11-92

Peri-spinal subarachnoid (intrathecal; i.t.) injection of non-viral naked plasmid DNA encoding the anti-inflammatory cytokine, IL-10 (pDNA-IL-10) suppresses chronic neuropathic pain in animal models. However, two sequential i.t. pDNA injections are required within a discrete 5 to 72-hour period for prolonged efficacy. Previous reports identified phagocytic immune cells present in the peri-spinal milieu surrounding the i.t injection site that may play a role in transgene uptake resulting in subsequent IL-10 transgene expression.
In the present study, we aimed to examine whether factors known to induce pro-phagocytic anti-inflammatory properties of immune cells improve i.t. IL-10 transgene uptake using reduced naked pDNA-IL-10 doses previously determined ineffective. Both the synthetic glucocorticoid, dexamethasone, and the hexose sugar, D-mannose, were factors examined that could optimize i.t. pDNA-IL-10 uptake leading to enduring suppression of neuropathic pain as assessed by light touch sensitivity of the rat hindpaw (allodynia).
Compared to dexamethasone, i.t. mannose pretreatment significantly and dose-dependently prolonged pDNA-IL-10 pain suppressive effects, reduced spinal IL-1β and enhanced spinal and dorsal root ganglia IL-10 immunoreactivity. Macrophages exposed to D-mannose revealed reduced proinflammatory TNF-α, IL-1β, and nitric oxide, and increased IL-10 protein release, while IL-4 revealed no improvement in transgene uptake. Separately, D-mannose dramatically increased pDNA-derived IL-10 protein release in culture supernatants. Lastly, a single i.t. co-injection of mannose with a 25-fold lower pDNA-IL-10 dose produced prolonged pain suppression in neuropathic rats.
Peri-spinal treatment with D-mannose may optimize naked pDNA-IL-10 transgene uptake for suppression of allodynia, and is a novel approach to tune spinal immune cells toward pro-phagocytic phenotype for improved non-viral gene therapy.