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

• Published in: Scientific reports 2016-12, Vol.6 (1), p.38387-38387, Article 38387
• Main Authors: Watanabe, Mitsuru, Masaki, Katsuhisa, Yamasaki, Ryo, Kawanokuchi, Jun, Takeuchi, Hideyuki, Matsushita, Takuya, Suzumura, Akio, Kira, Jun-ichi
• Format: Article
• Language: English
• Subjects: 13/31; 14/19; 14/34; 631/250/371; 631/378/2596/1308; 64/60; 692/617/375/1411/1666; 82/80; Animals; Astrocytes; Astrocytes - metabolism; Astrocytes - pathology; CD11b antigen; Cell Communication - genetics; Cell Communication - immunology; Cell culture; Cell signaling; Connexin 43; Connexin 43 - genetics; Demyelination; Disease Models, Animal; Gap junctions; Gap Junctions - genetics; Gap Junctions - pathology; Gene Expression Regulation - drug effects; Humanities and Social Sciences; Humans; Inflammation; Interferon-gamma - genetics; Interferon-gamma - metabolism; Interleukin 17; Interleukin-17 - genetics; Interleukin-17 - immunology; Interleukin-17 - metabolism; Interleukin-1beta - genetics; Interleukin-1beta - metabolism; Interleukin-4 - immunology; Interleukin-4 - metabolism; Lesions; Lymphocytes T; Macrophage Activation - genetics; Macrophage Activation - immunology; Media; Mice; Microglia; Microglia - metabolism; mRNA; multidisciplinary; Multiple sclerosis; Multiple Sclerosis - genetics; Multiple Sclerosis - immunology; Multiple Sclerosis - physiopathology; Neuroglia - metabolism; Neuroglia - pathology; Proteins; Rodents; Science; Th1 Cells - drug effects; Th1 Cells - immunology; Th1 Cells - metabolism; γ-Interferon
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep38387

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 IFNγ 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.