Autoantibodies recognizing native MOG are closely associated with active demyelination but not with neuroinflammation in chronic EAE

It is important to find biomarkers for autoimmune inflammation and demyelination in the CNS to monitor disease status in patients with multiple sclerosis (MS). For this purpose, we determined the titers of antibodies (Ab) reacting with native myelin oligodendrocyte glycoprotein (MOG)‐expressing cells to evaluate the disease activity of chronic experimental autoimmune encephalomyelitis (EAE) in rats and the relationship between anti‐MOGcme (cell membrane‐expressed MOG), Ab titers and clinical and pathological parameters were evaluated. Consequently, we found that elevation of anti‐MOGcme Ab titers was associated with clinical severity, except for some cases in very late stages and with severe and widespread demyelination but with dominant inflammation. In contrast, antibodies detected by standard ELISA using recombinant MOG were elevated in both symptomatic and asymptomatic rats and were not associated with parameters such as inflammation and demyelination. Longitudinal examination of anti‐MOGcme Ab titers in individual rats revealed that Ab titers accurately reflect disease activity. Furthermore, anti‐MOGcme Ab titer was not elevated in acute EAE without demyelination. These findings suggest that autoantibodies reacting with native and glycosylated MOG play an important role in the progression of demyelinating diseases and could be biomarkers for monitoring the status of patients with MS.