Stress-induced neuroinflammation is mediated by GSK3-dependent TLR4 signaling that promotes susceptibility to depression-like behavior

Yuyan Cheng, Marta Pardo, Rubia de Souza Armini, Ana Martinez, Hadley Mouhsine, Jean Francois Zagury, Richard S. Jope, Eleonore Beurel

Research output: Contribution to journalArticlepeer-review

68 Scopus citations

Abstract

Most psychiatric and neurological diseases are exacerbated by stress. Because this may partially result from stress-induced inflammation, we examined factors involved in this stress response. After a paradigm of inescapable foot shock stress that causes learned helplessness depression-like behavior, eighteen cytokines and chemokines increased in mouse hippocampus, peaking 6-12 h after stress. A 24 h prior pre-conditioning stress accelerated the rate of stress-induced hippocampal cytokine and chemokine increases, with most reaching peak levels after 1-3 h, often without altering the maximal levels. Toll-like receptor 4 (TLR4) was involved in this response because most stress-induced hippocampal cytokines and chemokines were attenuated in TLR4 knockout mice. Stress activated glycogen synthase kinase-3 (GSK3) in wild-type mouse hippocampus, but not in TLR4 knockout mice. Administration of the antidepressant fluoxetine or the GSK3 inhibitor TDZD-8 reduced the stress-induced increases of most hippocampal cytokines and chemokines. Stress increased hippocampal levels of the danger-associated molecular pattern (DAMP) protein high mobility group box 1 (HMGB1), activated the inflammatory transcription factor NF-κB, and the NLRP3 inflammasome. Knockdown of HMGB1 blocked the acceleration of cytokine and chemokine increases in the hippocampus caused by two successive stresses. Fluoxetine treatment blocked stress-induced up-regulation of HMGB1 and subsequent NF-κB activation, whereas TDZD-8 administration attenuated NF-κB activation downstream of HMGB1. To test if stress-induced cytokines and chemokines contribute to depression-like behavior, the learned helplessness model was assessed. Antagonism of TNFα modestly reduced susceptibility to learned helplessness induction, whereas TLR4 knockout mice were resistant to learned helplessness. Thus, stress-induces a broad inflammatory response in mouse hippocampus that involves TLR4, GSK3, and downstream inflammatory signaling, and these stress responses contribute to susceptibility to depression-like behavior in mice.

Original languageEnglish (US)
Pages (from-to)207-222
Number of pages16
JournalBrain, Behavior, and Immunity
Volume53
DOIs
StatePublished - Mar 1 2016

Keywords

  • Depression
  • Fluoxetine
  • Glycogen synthase kinase-3
  • Neuroinflammation
  • Stress
  • Toll-like receptor 4

ASJC Scopus subject areas

  • Immunology
  • Endocrine and Autonomic Systems
  • Behavioral Neuroscience

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