Microbiota modulation by teriflunomide therapy in people with multiple sclerosis: An observational case-control study.

Multiple sclerosis (MS) is a chronic immune-mediated and heterogeneous disease characterized by demyelination, axonal damage, and physical and cognitive impairment. Recent studies have highlighted alterations in the microbiota of people with MS (pwMS). However, the intricate nature of the disease and the wide range of treatments available make it challenging to identify specific microbial populations or functions associated with MS symptoms and disease progression. This study aimed to characterize the microbiota of pwMS treated with the oral drug teriflunomide (TF) and compare it with that of pwMS treated with beta interferons (IFNβ), pwMS treated with no previous disease modifying therapies (naïve), and healthy controls. Our findings demonstrate significant alterations in both the composition and function of the gut microbiota in pwMS that are further influenced by disease-modifying therapies. Specifically, oral treatment with TF had a notable impact on the gut microbiota of pwMS. Importantly, the dysregulated microbial environment within the gut was associated with symptoms commonly experienced by pwMS, including fatigue, anxiety, and depression.