Modulation of TNF release by choline requires alpha7 subunit nicotinic acetylcholine receptor-mediated signaling

Mol Med. 2008 Sep-Oct;14(9-10):567-74. doi: 10.2119/2008-00079.Parrish.

Abstract

The alpha7 subunit-containing nicotinic acetylcholine receptor (alpha7nAChR) is an essential component in the vagus nerve-based cholinergic anti-inflammatory pathway that regulates the levels of TNF, high mobility group box 1 (HMGB1), and other cytokines during inflammation. Choline is an essential nutrient, a cell membrane constituent, a precursor in the biosynthesis of acetylcholine, and a selective natural alpha7nAChR agonist. Here, we studied the anti-inflammatory potential of choline in murine endotoxemia and sepsis, and the role of the alpha7nAChR in mediating the suppressive effect of choline on TNF release. Choline (0.1-50 mM) dose-dependently suppressed TNF release from endotoxin-activated RAW macrophage-like cells, and this effect was associated with significant inhibition of NF-kappaB activation. Choline (50 mg/kg, intraperitoneally [i.p.]) treatment prior to endotoxin administration in mice significantly reduced systemic TNF levels. In contrast to its TNF suppressive effect in wild type mice, choline (50 mg/kg, i.p.) failed to inhibit systemic TNF levels in alpha7nAChR knockout mice during endotoxemia. Choline also failed to suppress TNF release from endotoxin-activated peritoneal macrophages isolated from alpha7nAChR knockout mice. Choline treatment prior to endotoxin resulted in a significantly improved survival rate as compared with saline-treated endotoxemic controls. Choline also suppressed HMGB1 release in vitro and in vivo, and choline treatment initiated 24 h after cecal ligation and puncture (CLP)-induced polymicrobial sepsis significantly improved survival in mice. In addition, choline suppressed TNF release from endotoxin-activated human whole blood and macrophages. Collectively, these data characterize the anti-inflammatory efficacy of choline and demonstrate that the modulation of TNF release by choline requires alpha7nAChR-mediated signaling.

Publication types

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

MeSH terms

  • Animals
  • Anti-Inflammatory Agents / pharmacology*
  • Cell Line
  • Cells, Cultured
  • Choline / pharmacology*
  • Choline / physiology*
  • Endotoxemia / drug therapy
  • Endotoxemia / immunology
  • Endotoxemia / metabolism
  • Endotoxemia / mortality
  • Endotoxins / immunology
  • Female
  • Gene Expression Regulation
  • HMGB1 Protein / metabolism
  • Humans
  • Macrophages / drug effects
  • Macrophages / immunology
  • Macrophages / metabolism*
  • Macrophages, Peritoneal / immunology
  • Macrophages, Peritoneal / metabolism
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Receptors, Nicotinic / genetics
  • Receptors, Nicotinic / metabolism*
  • Sepsis / drug therapy
  • Sepsis / immunology
  • Sepsis / metabolism
  • Sepsis / mortality
  • Signal Transduction*
  • Tumor Necrosis Factor-alpha / metabolism*
  • alpha7 Nicotinic Acetylcholine Receptor

Substances

  • Anti-Inflammatory Agents
  • Chrna7 protein, human
  • Chrna7 protein, mouse
  • Endotoxins
  • HMGB1 Protein
  • Receptors, Nicotinic
  • Tumor Necrosis Factor-alpha
  • alpha7 Nicotinic Acetylcholine Receptor
  • Choline