Alterations of the gut mycobiome in patients with MS

The mycobiome is the fungal component of the gut microbiome and is implicated in several autoimmune diseases. However, its role in MS has not been studied. We performed ITS sequencing and characterized the gut mycobiome in people with MS (pwMS) and healthy controls at baseline and after six months.The mycobiome had significantly higher alpha diversity and inter-subject variation in pwMS than controls. Saccharomyces and Aspergillus were over-represented in pwMS. Saccharomyces was positively correlated with circulating basophils and negatively correlated with regulatory B cells, while Aspergillus was positively correlated with activated CD16+ dendritic cells in pwMS. Different mycobiome profiles, defined as mycotypes, were associated with different bacterial microbiome and immune cell subsets in the blood. Initial treatment with dimethyl fumarate, a common immunomodulatory therapy which also has fungicidal activity, did not cause uniform gut mycobiome changes across all pwMS.