Peripheral interleukin-4 ameliorates inflammatory macrophage-dependent neuropathic pain

Pain. 2015 Apr;156(4):684-693. doi: 10.1097/j.pain.0000000000000097.

Abstract

There is increasing evidence that inflammatory (M1-polarized) macrophages drive the nonresolving neuroinflammation that causes neuropathic pain after nerve injury. As interleukin-4 (IL-4) promotes the suppressive (M2-polarized) state in macrophages, we examined whether exploiting an IL-4-mediated pathway could ameliorate M1 macrophage-dependent neuropathic pain. The mRNA and protein expression of IL-4 receptor α chain (IL-4Rα) were upregulated in accumulating F4/80 macrophages in injured sciatic nerve (SCN). In mouse macrophage cell line J774A.1, IL-4 downregulated the mRNA expression of M1 macrophage-specific molecules (IL-1β, CC chemokine ligand 3, and CD86) normally provoked by lipopolysaccharide, while increasing the mRNA expression of M2 macrophage-specific molecules (arginase-1, IL-10, and CD206) through a STAT6-mediated pathway. In ex vivo SCN culture, M1 molecules were highly expressed in the injured SCN on day 7 after partial SCN ligation (PSL) but were decreased by IL-4 treatment. In contrast, M2 molecules were upregulated by IL-4. IL-4 also increased phosphorylated STAT6 (pSTAT6) expression and shifted IL-1β M1 macrophages toward a CD206 M2 phenotype. Perineural administration of IL-4 in mice subject to PSL ameliorated development and maintenance of tactile allodynia and thermal hyperalgesia. These effects of IL-4 were based on that IL-4 treatment increased the proportions of pSTAT6 and CD206 macrophages in injured SCN on day 14 after PSL. We found that neuropathic pain can be ameliorated by IL-4 treatment, which exerts its therapeutic effect on accumulating macrophages through a STAT6-dependent pathway. A shift in macrophage phenotype from the inflammatory to the suppressive phenotype, driven by IL-4R signaling, may have benefits in the treatment of neuropathic pain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antirheumatic Agents / pharmacology
  • Antirheumatic Agents / therapeutic use*
  • Cell Polarity / drug effects
  • Cells, Cultured
  • Cytokines / metabolism
  • Disease Models, Animal
  • Gene Expression Regulation / drug effects
  • Humans
  • Hyperalgesia / physiopathology*
  • Inflammation* / drug therapy
  • Inflammation* / etiology
  • Inflammation* / pathology
  • Interleukin-4 / therapeutic use*
  • Lipopolysaccharides / pharmacology
  • Macrophages / drug effects*
  • Macrophages / metabolism
  • Male
  • Mice
  • Mice, Inbred ICR
  • Pain Measurement
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism
  • STAT6 Transcription Factor / metabolism
  • Sciatica / complications*
  • Sciatica / pathology
  • Signal Transduction / drug effects
  • Up-Regulation / drug effects

Substances

  • Antirheumatic Agents
  • Cytokines
  • Il4ra protein, mouse
  • Lipopolysaccharides
  • Receptors, Cell Surface
  • STAT6 Transcription Factor
  • Interleukin-4