High mobility group box 1/Toll-like receptor danger signaling increases brain neuroimmune activation in alcohol dependence

Biol Psychiatry. 2013 Apr 1;73(7):602-12. doi: 10.1016/j.biopsych.2012.09.030. Epub 2012 Dec 1.


Background: Innate immune gene expression is regulated in part through high mobility group box 1 (HMGB1), an endogenous proinflammatory cytokine, that activates multiple members of the interleukin-1/Toll-like receptor (TLR) family associated with danger signaling. We investigated expression of HMGB1, TLR2, TLR3, and TLR4 in chronic ethanol-treated mouse brain, postmortem human alcoholic brain, and rat brain slice culture to test the hypothesis that neuroimmune activation in alcoholic brain involves ethanol activation of HMGB1/TLR danger signaling.

Methods: Protein levels were assessed using Western blot, enzyme-linked immunosorbent assay, and immunohistochemical immunoreactivity (+IR), and messenger RNA (mRNA) levels were measured by real time polymerase chain reaction in ethanol-treated mice (5 g/kg/day, intragastric, 10 days + 24 hours), rat brain slice culture, and postmortem human alcoholic brain.

Results: Ethanol treatment of mice increased brain mRNA and +IR protein expression of HMGB1, TLR2, TLR3, and TLR4. Postmortem human alcoholic brain also showed increased HMGB1, TLR2, TLR3, and TLR4 +IR cells that correlated with lifetime alcohol consumption, as well as each other. Ethanol treatment of brain slice culture released HMGB1 into the media and induced the proinflammatory cytokine, interleukin-1 beta (IL-1β). Neutralizing antibodies to HMGB1 and small inhibitory mRNA to HMGB1 or TLR4 blunted ethanol induction of IL-1β.

Conclusions: Ethanol-induced HMGB1/TLR signaling contributes to induction of the proinflammatory cytokine, IL-1β. Increased expression of HMGB1, TLR2, TLR3, and TLR4 in alcoholic brain and in mice treated with ethanol suggests that chronic alcohol-induced brain neuroimmune activation occurs through HMGB1/TLR signaling.

Publication types

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

MeSH terms

  • Adult
  • Alcoholism / metabolism*
  • Animals
  • Brain / drug effects
  • Brain / metabolism*
  • Case-Control Studies
  • Ethanol / pharmacology
  • Gene Expression / drug effects
  • HMGB1 Protein / metabolism*
  • Humans
  • Interleukin-1beta / metabolism
  • Male
  • Mice
  • Middle Aged
  • Rats
  • Signal Transduction / drug effects
  • Toll-Like Receptor 2 / metabolism*
  • Toll-Like Receptor 3 / metabolism*
  • Toll-Like Receptor 4 / metabolism*


  • HMGB1 Protein
  • Interleukin-1beta
  • Toll-Like Receptor 2
  • Toll-Like Receptor 3
  • Toll-Like Receptor 4
  • Ethanol