Microglia at brain stab wounds express connexin 43 and in vitro form functional gap junctions after treatment with interferon-γ and tumor necrosis factor-α

Eliseo A. Eugenín, Dominik Eckardt, Martin Theis, Klaus Willecke, Michael V.L. Bennett, Juan C. Sáez

Research output: Contribution to journalArticlepeer-review

188 Scopus citations

Abstract

Gap junctional communication between microglia was investigated at rat brain stab wounds and in primary cultures of rat and mouse cells. Under resting conditions, rat microglia (FITC-isolectin-B4-reactive cells) were sparsely distributed in the neocortex, and most (95%) were not immunoreactive for Cx43, a gap junction protein subunit. At brain stab wounds, microglia progressively accumulated over several days and formed aggregates that frequently showed Cx43 immunoreactivity at interfaces between cells. In primary culture, microglia showed low levels of Cx43 determined by Western blotting, diffuse intracellular Cx43 immunoreactivity, and a low incidence of dye coupling. Treatment with the immunostimulant bacterial lipopolysaccharide (LPS) or the cytokines interferon-γ (INF-γ) or tumor necrosis factor-α (TNF-α) one at a time did not increase the incidence of dye coupling. However, microglia treated with INF-γ, plus LPS showed a dramatic increase in dye coupling that was prevented by coapplication of an anti-TNF-α antibody, suggesting the release and autocrine action of TNF-α. Treatment with INF-γ, plus TNF-α also greatly increased the incidence of dye coupling and the Cx43 levels with translocation of Cx43 to cell-cell contacts. The cytokine-induced dye coupling was reversibly inhibited by 18α-glycyrrhetinic acid, a gap junction blocker. Cultured mouse microglia also expressed Cx43 and developed dye coupling upon treatment with cytokines, but microglia from homozygous Cx43-deficient mice did not develop significant dye coupling after treatment with either INF-γ, plus LPS or INF-γ plus TNF-α. This report demonstrates that microglia can communicate with each other through gap junctions that are induced by inflammatory cytokines, a process that may be important in the elaboration of the inflammatory response.

Original languageEnglish (US)
Pages (from-to)4190-4195
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume98
Issue number7
DOIs
StatePublished - Mar 27 2001

Keywords

  • Connexin
  • Cytokines
  • Dye coupling
  • Inflammation
  • Macrophage

ASJC Scopus subject areas

  • General

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