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

J Neuroinflammation. 2014 May 21:11:92. doi: 10.1186/1742-2094-11-92.

Abstract

Background: 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.

Methods: 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).

Results: 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.

Conclusions: 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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Anti-Inflammatory Agents / therapeutic use*
  • Cells, Cultured
  • Chronic Disease
  • Constriction, Pathologic / complications
  • Cytokines / genetics
  • Cytokines / metabolism
  • Dexamethasone / therapeutic use
  • Disease Models, Animal
  • Genetic Therapy*
  • Interleukin-10 / biosynthesis
  • Interleukin-10 / therapeutic use*
  • Male
  • Mannose / therapeutic use*
  • Mice
  • Microphthalmos / drug therapy
  • Microphthalmos / metabolism
  • Neuralgia / etiology
  • Neuralgia / therapy*
  • Nitric Oxide / metabolism
  • Pain Threshold / physiology*
  • Rats
  • Rats, Sprague-Dawley
  • Spinal Cord / metabolism
  • Spinal Cord / physiology

Substances

  • Anti-Inflammatory Agents
  • Cytokines
  • Interleukin-10
  • Nitric Oxide
  • Dexamethasone
  • Mannose