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

BACKGROUND: 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. METHODS: Because glutamate aspartate transporter (GLAST)+ astroglia are enriched in the brain gray matter, we generated Cx43fl/fl;GLAST-CreERT2/+ mice that were brain gray matter astroglia-specific Cx43 conditional knockouts (Cx43 icKO). EAE was induced by immunization with myelin oligodendroglia glycoprotein (MOG) 35-55 peptide 10 days after tamoxifen injection. Cx43fl/fl mice were used as controls. RESULTS: 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. CONCLUSIONS: 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.

Oligodendroglial connexin 47 regulates neuroinflammation upon autoimmune demyelination in a novel mouse model of multiple sclerosis.

In multiple sclerosis plaques, oligodendroglial connexin (Cx) 47 constituting main gap junction channels with astroglial Cx43 is persistently lost. As mice with Cx47 single knockout exhibit no demyelination, the roles of Cx47 remain undefined. We aimed to clarify the effects of oligodendroglia-specific Cx47 inducible conditional knockout (icKO) on experimental autoimmune encephalomyelitis (EAE) induced by myelin oligodendrocyte glycoprotein peptide (MOG35-55) in PLP/CreERT;Cx47fl/fl mice at 14 d after tamoxifen injection. Cx47 icKO mice demonstrated exacerbation of acute and chronic relapsing EAE with more pronounced demyelination than Cx47 flox (fl)/fl littermates. CD3+ T cells more abundantly infiltrated the spinal cord in Cx47 icKO than in Cx47 fl/fl mice throughout the acute to chronic phases. CXCR3-CCR6+CD4+ and IL17+IFNγ-CD4+ helper T (Th) 17 cells isolated from spinal cord and brain tissues were significantly increased in Cx47 icKO mice compared with Cx47 fl/fl mice, while MOG35-55-specific proliferation and proinflammatory cytokine production of splenocytes were unaltered. Microarray analysis of isolated microglia revealed stronger microglial activation toward proinflammatory and injury-response phenotypes with increased expressions of chemokines that can attract Th17 cells, including Ccl2, Ccl3, Ccl4, Ccl7, and Ccl8, in Cx47 icKO mice compared with Cx47 fl/fl mice. In Cx47 icKO mice, NOS2+ and MHC class II+ microglia were more enriched immunohistochemically, and A1-specific astroglial gene expressions and astroglia immunostained for C3, a representative A1 astrocyte marker, were significantly increased at the acute phase, compared with Cx47 fl/fl mice. These findings suggest that oligodendroglia-specific Cx47 ablation induces severe inflammation upon autoimmune demyelination, underscoring a critical role for Cx47 in regulating neuroinflammation.

[Case of post-transfusion posterior reversible encephalopathy syndrome with cerebral hemorrhage that may be associated with fat-soluble vitamin deficiency].

A 36-year-old woman with a 4 year history of lower legs edema, hypermenorrhea and melena without medical treatment was admitted to our hospital. At 18 days before admission, anasarca and general fatigue appeared and she was admitted to another hospital. Her hemoglobin concentration was 1.4 g/dl and chest X-ray showed cardiomegaly. Heart failure with severe chronic anemia was diagnosed, and blood transfusion was performed. Her hemoglobin concentration increased to 10 g/dl and the anasarca disappeared. The day after discharge, she was referred to our hospital with generalized convulsion. We diagnosed posterior reversible encephalopathy syndrome (PRES) from the typical MRI imaging. We started treatment and her consciousness recovered steadily. At a week after admission, left hemiparesis appeared. Her brain imaging revealed multiple intracranial hemorrhages. In addition, her visual disturbance revealed vitamin A and vitamin K deficiency. PRES sometimes occur secondary to blood transfusion, but secondary brain hemorrhage is rare. Her fat-soluble vitamin deficiency, which resulted from a peculiar eating habit, may have contributed to the brain hemorrhage.

[Case of non-convulsive status epilepticus after influenza virus B infection].

A 24-year-old woman was referred to our hospital because of impaired consciousness after influenza virus B infection. Neurological examination revealed mild disturbance of consciousness without other neurological abnormalities. Laboratory tests showed elevated serum CRP, IL-6 and TNF-α levels. The level of IL-6 in the cerebrospinal fluid was also slightly elevated. Electroencephalography (EEG) disclosed almost continuous generalized spike and wave complexes and multiple spikes and wave complexes at 1.5-3 Hz. Brain MRI was normal. She was diagnosed as having influenza encephalopathy presenting non-convulsive status epilepticus (NCSE), and commenced methylprednisolone pulse therapy followed by prednisolone with gradual tapering. She was also treated with intravenous phenytoin and oral sodium valproate for NCSE. The next day, her consciousness level had improved. Although she became alert, epileptic discharges on EEG were still observed on the seventh hospital day, and levetiracetam was added. Then, her epileptic discharges almost completely disappeared on the twelfth hospital day. She was discharged without any neurological deficit. We consider this patient to be a case of transient NCSE due to influenza encephalopathy; alternatively, she may have epileptic traits and her NCSE may have been provoked by influenza virus infection.