Gray but not white matter astroglia-specific connexin 43 ablation ameliorates neuroinflammation [Agilent]

Objective: We previously reported that white matter connexin43 (Cx43) may related to the severity of the multiple sclerosis (MS), whereas the role of gray matter Cx43 in demyelinating disease is unknown. It was considered MS lesions were only exist in white matter, but recent studies revealed that demyelinating lesions are also exist in the cerebral cortex. This fact suggest the possibility that gray matter is somewhat related to the pathophysiology of MS. In this study, we aimed to clarify the role of gray matter Cx43 in a mouse model of MS (experimental autoimmune encephalomyelitis [EAE]). Methods: We developed Cx43F/F;Glutamate aspartate transporter (GLAST)-CreER(T2)KI/+ mice as gray matter specific Cx43 conditional knock-out (Cx43cKO) mice. We induced MOG-EAE 10 days after tamoxifen injection, and analyze its clinical course and pathology. We used Cx43F/F mice as controls. Results: EAE was significantly milder in gray matter astrocyte-specific Cx43cKO mice from acute phase to chronic phase, as compared with control mice. Pathology demonstrated less demyelinating lesions and infiltrating cells. Infiltrating immune cells did not express Cx43 in the active demyelinating lesions of the lumbar cord in both groups. The expression level of Cx43 was similar between these two groups in the spleen and the inguinal lymph nodes. Interpretation: Acute KO of gray matter specific Cx43 before induction of EAE reduce its aggressiveness. This finding may suggest the possibility that gray matter Cx43 modify the MS pathophysiology. We used connexin 43 inducible conditional knockout-mice to see the difference in disease severity of EAE with or without the white matter connexin 43. Cx43F_F means control mice brain sample without deletion of Cx43 expression. Cx43cKO means Cx43 depleted mice. 1 means pre-immunized, 2 means the onset phase of the disease, and 3 means the peak stage of the disease.