Ethanol-Induced TLR4/NLRP3 Neuroinflammatory Response in Microglial Cells Promotes Leukocyte Infiltration Across the BBB

Neurochem Res. 2016 Feb;41(1-2):193-209. doi: 10.1007/s11064-015-1760-5. Epub 2015 Nov 11.


We reported that the ethanol-induced innate immune response by activating TLR4 signaling triggers gliosis and neuroinflammation. Ethanol also activates other immune receptors, such as NOD-like-receptors, and specifically NLRP3-inflammasome in astroglial cells, to stimulate caspase-1 cleavage and IL-1β and IL-18 cytokines production. Yet, whether microglia NLRs are also sensitive to the ethanol effects that contribute to neuroinflammation is uncertain. Using cerebral cortexes of the chronic alcohol-fed WT and TLR4(-/-) mice, we demonstrated that chronic ethanol treatment enhanced TLR4 mediated-NLRP3/Caspase-1 complex activation, and up-regulated pro-inflammatory cytokines and chemokines levels. Ethanol-induced NLRP3-inflammasome activation and mitochondria-ROS generation were also observed in cultured microglial cells. The up-regulation of CD45(high)/CD11b(+) cell populations and matrix metalloproteinase-9 levels was also noted in the cortexes of the ethanol-treated WT mice. Notably, elimination of the TLR4 function abolished most ethanol-induced neuroinflammatory effects. Thus, our results demonstrate that ethanol triggers TLR4-mediated NLRP3-inflammasome activation in glial cells, and suggest that microglia stimulation may compromise the permeability of blood-brain barrier events to contribute to ethanol-induced neuroinflammation and brain damage.

Keywords: Alcohol; BBB; Leukocyte infiltration; Matrix metalloproteinase; Microglia; TLR4.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blood-Brain Barrier*
  • Carrier Proteins / physiology*
  • Central Nervous System / cytology
  • Central Nervous System / drug effects
  • Ethanol / toxicity*
  • Female
  • Leukocytes / cytology*
  • Mice
  • Mice, Inbred C57BL
  • Microglia / cytology
  • Microglia / drug effects*
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • Toll-Like Receptor 4 / physiology*


  • Carrier Proteins
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • Nlrp3 protein, mouse
  • Tlr4 protein, mouse
  • Toll-Like Receptor 4
  • Ethanol