Protective autoimmunity: Interferon-γ enables microglia to remove glutamate without evoking inflammatory mediators

I. Shaked, D. Tchoresh, R. Gersner, G. Meiri, S. Mordechai, X. Xiao, R. P. Hart, Michal Schwartz

Research output: Contribution to journalArticlepeer-review

183 Scopus citations

Abstract

Glutamate in excessive amounts is a major contributor to neuronal degeneration, and its removal is attributed mainly to astrocytes. Traumatic injury to the central nervous system (CNS) is often accompanied by disappearance of astrocytes from the lesion site and failure of the remaining cells to withstand the ensuing toxicity. Microglia that repopulate the lesion site are the usual suspects for causing redox imbalance and inflammation and thus further exacerbating the neurotoxicity. However, our group recently demonstrated that early post-injury activation of microglia as antigen-presenting cells correlates with an ability to withstand injurious conditions. Moreover, we found that T cells reactive to CNS-specific self-antigens protected neurons against glutamate toxicity. Here, we show that antigen-specific autoimmune T cells, by tailoring the microglial phenotype, can increase the ability of microglia-enriched cultures to remove glutamate. This T-cell-mediated effect could not be achieved by the potent microglia-activating agent lipopolysaccharide (LPS), but was dose-dependently reproduced by the Th1 cytokine interferon (IFN)-γ and significantly reduced by neutralizing anti-IFN-γ antibodies. Under the same conditions, IFN-γ had no effect on cultured astrocytes. Up-regulation of glutamate uptake induced by IFN-γ activation was not accompanied by the acute inflammatory response seen in LPS-activated cultures. These findings suggest that T cells or their cytokines can cause microglia to adopt a phenotype that facilitates rather than impairs glutamate clearance, possibly contributing to restoration of homeostasis.

Original languageEnglish
Pages (from-to)997-1009
Number of pages13
JournalJournal of Neurochemistry
Volume92
Issue number5
DOIs
StatePublished - 1 Mar 2005
Externally publishedYes

Keywords

  • Central nervous system degeneration
  • Central nervous system inflammation
  • Glutamate toxicity
  • Neuroprotection
  • Protective autoimmunity

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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