AUTHOR=Sato Fumitaka , Nakamura Yumina , Katsuki Aoshi , Khadka Sundar , Ahmad Ijaz , Omura Seiichi , Martinez Nicholas E. , Tsunoda Ikuo 

TITLE=Curdlan, a Microbial β-Glucan, Has Contrasting Effects on Autoimmune and Viral Models of Multiple Sclerosis

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=Volume 12 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2022.805302

DOI=10.3389/fcimb.2022.805302

ISSN=2235-2988

ABSTRACT=Multiple sclerosis (MS) is an immune-mediated disease characterized by inflammatory demyelination and axonal degeneration in the central nervous system (CNS).  Bacterial and fungal infections have been associated with the development of MS; there are several microbial candidate components that are commonly present in several microbes and potentially contribute to MS pathogenesis.  Among such candidates, curdlan is a microbial 1,3--glucan that can stimulate dendritic cells, and enhances T helper (Th) 17 responses.  We determined whether curdlan administration could affect two animal models for MS: an autoimmune model, experimental autoimmune encephalomyelitis (EAE), and a viral model, Theiler’s murine encephalomyelitis virus (TMEV)-induced demyelinating disease (TMEV-IDD).  We induced relapsing-remitting EAE by sensitizing SJL/J mice with myelin proteolipid protein (PLP)139-151 peptide and found that curdlan treatment prior to PLP sensitization converted the clinical course of EAE into hyperacute EAE, in which the mice developed a primary progressive motor paralysis and died in 2 weeks.  Curdlan-treated EAE mice had massive infiltration of T cells and neutrophils in the CNS with higher levels of Th17 and Th1 responses, compared with the control EAE mice.  On the other hand, in TMEV-IDD, we found that curdlan treatment reduced the clinical scores and axonal degeneration without changes in inflammation or virus persistence in the CNS.  In summary, although curdlan administration exacerbated the autoimmune MS model by enhanced inflammatory demyelination, it suppressed the viral MS model with reduced axonal degeneration.  Therefore, microbial infections may play contrasting roles in MS depending on its etiology: autoimmunity versus viral infection.