Brain gray matter astroglia-specific connexin 43 ablation attenuates spinal cord inflammatory demyelination

• Published in: Journal of neuroinflammation 2021-06, Vol.18 (1), p.126-126, Article 126
• Main Authors: Une, Hayato, Yamasaki, Ryo, Nagata, Satoshi, Yamaguchi, Hiroo, Nakamuta, Yuko, Indiasari, Ulfa Camelia, Cui, Yiwen, Shinoda, Koji, Masaki, Katsuhisa, Götz, Magdalena, Kira, Jun-Ichi
• Format: Article
• Language: English
• Subjects: Ablation; Ablation (Surgery); Animal models; Animals; Astrocytes; Astrocytes - metabolism; Astrocytes - pathology; Astroglia; Brain research; Care and treatment; CD45 antigen; Central nervous system diseases; Cerebellum; Cerebral cortex; Cerebrospinal fluid; Cerebrum; Chemokine; Chemokines; Chemokines - cerebrospinal fluid; Connexin 43; Connexin 43 - deficiency; Connexin 43 - genetics; Connexin 43 - metabolism; Cytokines; Cytokines - cerebrospinal fluid; Demyelinating Diseases - etiology; Demyelinating Diseases - physiopathology; Demyelination; Development and progression; Disease Models, Animal; DNA microarrays; Encephalomyelitis, Autoimmune, Experimental - genetics; Experimental allergic encephalomyelitis; Experimental autoimmune encephalomyelitis; Experiments; Gene Expression; Gray Matter - metabolism; Gray Matter - pathology; Health aspects; Immunization; Inflammation; Interleukin 10; Laboratories; Macrophages; Membrane proteins; Metabolism; Mice; Mice, Knockout; Microglia; Monocyte chemoattractant protein 1; Multiple sclerosis; Multiple Sclerosis - physiopathology; Myelin; Neuroinflammatory Diseases - etiology; Neuroinflammatory Diseases - genetics; Neuroinflammatory Diseases - physiopathology; Oligodendrocyte-myelin glycoprotein; Oligodendrocytes; Paralysis; Phenotypes; Spinal cord; Spinal Cord - immunology; Spinal Cord - pathology; Substantia grisea; Therapeutic targets; γ-Interferon
• ISSN: 1742-2094; 1742-2094
• DOI: 10.1186/s12974-021-02176-1

Brain astroglia are activated preceding the onset of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). We characterized the effects of brain astroglia on spinal cord inflammation, focusing on astroglial connexin (Cx)43, because we recently reported that Cx43 has a critical role in regulating neuroinflammation. Because glutamate aspartate transporter (GLAST) astroglia are enriched in the brain gray matter, we generated Cx43 ;GLAST-CreER mice that were brain gray matter astroglia-specific Cx43 conditional knockouts (Cx43 icKO). EAE was induced by immunization with myelin oligodendroglia glycoprotein (MOG) peptide 10 days after tamoxifen injection. Cx43 mice were used as controls. Acute and chronic EAE signs were significantly milder in Cx43 icKO mice than in controls whereas splenocyte MOG-specific responses were unaltered. Histologically, Cx43 icKO mice showed significantly less demyelination and fewer CD45 infiltrating immunocytes, including F4/80 macrophages, and Iba1 microglia in the spinal cord than controls. Microarray analysis of the whole cerebellum revealed marked upregulation of anti-inflammatory A2-specific astroglia gene sets in the pre-immunized phase and decreased proinflammatory A1-specific and pan-reactive astroglial gene expression in the onset phase in Cx43 icKO mice compared with controls. Astroglia expressing C3, a representative A1 marker, were significantly decreased in the cerebrum, cerebellum, and spinal cord of Cx43 icKO mice compared with controls in the peak phase. Isolated Cx43 icKO spinal microglia showed more anti-inflammatory and less proinflammatory gene expression than control microglia in the pre-immunized phase. In particular, microglial expression of Ccl2, Ccl5, Ccl7, and Ccl8 in the pre-immunized phase and of Cxcl9 at the peak phase was lower in Cx43 icKO than in controls. Spinal microglia circularity was significantly lower in Cx43 icKO than in controls in the peak phase. Significantly lower interleukin (IL)-6, interferon-γ, and IL-10 levels were present in cerebrospinal fluid from Cx43 icKO mice in the onset phase compared with controls. The ablation of Cx43 in brain gray matter astroglia attenuates EAE by promoting astroglia toward an anti-inflammatory phenotype and suppressing proinflammatory activation of spinal microglia partly through depressed cerebrospinal fluid proinflammatory cytokine/chemokine levels. Brain astroglial Cx43 might be a novel therapeutic target for MS.