Stimulation of alpha 7 cholinergic receptors inhibits lipopolysaccharide-induced neutrophil recruitment by a tumor necrosis factor alpha-independent mechanism

Shock. 2007 Apr;27(4):443-7. doi: 10.1097/01.shk.0000245016.78493.bb.

Abstract

The cholinergic nervous system controls inflammation by inhibiting the release of proinflammatory cytokines such as tumor necrosis factor (TNF) alpha from lipopolysaccharide (LPS)-stimulated macrophages. The key endogenous mediator of this so-called cholinergic anti-inflammatory pathway is acetylcholine, the principal neurotransmitter of the vagus nerve, which specifically interacts with alpha7 cholinergic receptors expressed by macrophages and other cell types to inhibit TNF-alpha production. We here investigated the capacity of the selective alpha7 cholinergic receptor agonist 3-(2,4-dimethoxybenzylidene) anabaseine (GTS-21) to inhibit LPS-induced inflammatory responses in mice in vivo. To this end, mice received an intraperitoneal injection of LPS (from Escherichia coli, 200 microg) preceded by GTS-21 (4 mg/kg) or vehicle. GTS-21 strongly inhibited LPS-induced TNF-alpha release into the peritoneal cavity and the circulation. In addition, GTS-21 attenuated the influx of neutrophils into peritoneal fluid upon administration of LPS. This inhibitory effect on neutrophil recruitment by GTS-21 was independent of its effect on TNF-alpha release, considering that etanercept, a potent TNF-alpha-blocking protein containing the extracellular domain of the p75 TNF-alpha receptor, did not influence LPS-induced neutrophil influx either in the presence or in the absence of GTS-21 treatment. GTS-21 did not reduce the local secretion of macrophage inflammatory protein 2 and keratinocyte-derived cytokine, suggesting that altered concentrations of these neutrophil-attracting chemokines did not contribute to GTS-21-induced inhibition of neutrophil migration. These data identify a novel anti-inflammatory effect of chemical alpha7 cholinergic receptor stimulation that is independent from its capacity to inhibit TNF-alpha production.

MeSH terms

  • Animals
  • Benzylidene Compounds / pharmacology
  • Cell Migration Inhibition*
  • Cytokines / metabolism
  • Female
  • Lipopolysaccharides / antagonists & inhibitors*
  • Lipopolysaccharides / pharmacology
  • Mice
  • Mice, Inbred C57BL
  • Neutrophil Infiltration / immunology*
  • Nicotinic Agonists / pharmacology
  • Pyridines / pharmacology
  • Receptors, Nicotinic / metabolism*
  • Receptors, Nicotinic / physiology
  • Tumor Necrosis Factor-alpha / physiology*
  • alpha7 Nicotinic Acetylcholine Receptor

Substances

  • Benzylidene Compounds
  • Chrna7 protein, mouse
  • Cytokines
  • Lipopolysaccharides
  • Nicotinic Agonists
  • Pyridines
  • Receptors, Nicotinic
  • Tumor Necrosis Factor-alpha
  • alpha7 Nicotinic Acetylcholine Receptor
  • 3-(2,4-dimethoxybenzylidene)anabaseine