Th1 cells downregulate connexin 43 gap junctions in astrocytes via microglial activation

Mitsuru Watanabe, Katsuhisa Masaki, Ryo Yamasaki, Jun Kawanokuchi, Hideyuki Takeuchi, Takuya Matsushita, Akio Suzumura, Jun Ichi Kira

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Abstract

We previously reported early and extensive loss of astrocytic connexin 43 (Cx43) in acute demyelinating lesions of multiple sclerosis (MS) patients. Because it is widely accepted that autoimmune T cells initiate MS lesions, we hypothesized that infiltrating T cells affect Cx43 expression in astrocytes, which contributes to MS lesion formation. Primary mixed glial cell cultures were prepared from newborn mouse brains, and microglia were isolated by anti-CD11b antibody-conjugated magnetic beads. Next, we prepared astrocyte-rich cultures and astrocyte/microglia-mixed cultures. Treatment of primary mixed glial cell cultures with interferon (IFN) γ, interleukin (IL)-4, or IL-17 showed that only IFNβ or IL-17 at high concentrations reduced Cx43 protein levels. Upon treatment of astrocyte-rich cultures and astrocyte/microglia-mixed cultures with IFNγ;, Cx43 mRNA/protein levels and the function of gap junctions were reduced only in astrocyte/microglia-mixed cultures. IFNγ-treated microglia-conditioned media and IL-1β, which was markedly increased in IFNγ-treated microglia-conditioned media, reduced Cx43 protein levels in astrocyte-rich cultures. Finally, we confirmed that Th1 cell-conditioned medium decreased Cx43 protein levels in mixed glial cell cultures. These findings suggest that Th1 cell-derived IFNγ activates microglia to release IL-1β that reduces Cx43 gap junctions in astrocytes. Thus, Th1-dominant inflammatory states disrupt astrocytic intercellular communication and may exacerbate MS.

Original languageEnglish
Article number38387
JournalScientific reports
Volume6
DOIs
Publication statusPublished - Dec 8 2016

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