Toll-like receptors 2, -3 and -4 prime microglia but not astrocytes across central nervous system regions for ATP-dependent interleukin-1β release

Sci Rep. 2014 Oct 29;4:6824. doi: 10.1038/srep06824.

Abstract

Interleukin-1β (IL-1β) is a crucial mediator in the pathogenesis of inflammatory diseases at the periphery and in the central nervous system (CNS). Produced as an unprocessed and inactive pro-form which accumulates intracellularly, release of the processed cytokine is strongly promoted by ATP acting at the purinergic P2X7 receptor (P2X7R) in cells primed with lipopolysaccharide (LPS), a Toll-like receptor (TLR) 4 ligand. Microglia are central to the inflammatory process and a major source of IL-1β when activated. Here we show that purified (>99%) microglia cultured from rat cortex, spinal cord and cerebellum respond robustly to ATP-dependent IL-1β release, upon priming with a number of TLR isoform ligands (zymosan and Pam3CSK4 for TLR2, poly(I:C) for TLR3). Cytokine release was prevented by a P2X7R antagonist and inhibitors of stress-activated protein kinases. Enriched astrocytes (≤ 5% microglia) from these CNS regions displayed responses qualitatively similar to microglia but became unresponsive upon eradication of residual microglia with the lysosomotropic agent Leu-Leu-OMe. Activation of multiple TLR isoforms in nervous system pathology, coupled with elevated extracellular ATP levels and subsequent P2X7R activation may represent an important route for microglia-derived IL-1β. This phenomenon may have important consequences for neuroinflammation and its position to the common pathology of CNS diseases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetamides / pharmacology
  • Adenosine Triphosphate / metabolism*
  • Animals
  • Astrocytes / drug effects
  • Astrocytes / metabolism*
  • Central Nervous System / drug effects
  • Central Nervous System / metabolism
  • Cerebellum / metabolism
  • Cerebral Cortex / metabolism
  • Interleukin-1beta / metabolism*
  • Ligands
  • Microglia / drug effects
  • Microglia / metabolism*
  • Quinolines / pharmacology
  • Rats
  • Signal Transduction
  • Spinal Cord / metabolism
  • Stress, Physiological
  • Toll-Like Receptor 2 / agonists
  • Toll-Like Receptor 2 / metabolism*
  • Toll-Like Receptor 3 / agonists
  • Toll-Like Receptor 3 / metabolism*
  • Toll-Like Receptor 4 / agonists
  • Toll-Like Receptor 4 / metabolism*

Substances

  • (N-(1-(((cyanoimino)(5-quinolinylamino) methyl) amino)-2,2-dimethylpropyl)-2-(3,4-dimethoxyphenyl)acetamide)
  • Acetamides
  • Interleukin-1beta
  • Ligands
  • Quinolines
  • Toll-Like Receptor 2
  • Toll-Like Receptor 3
  • Toll-Like Receptor 4
  • Adenosine Triphosphate