Pediatric multiple sclerosis (MS) is a chronic, life-long neurological condition associated with inflammation and degeneration in the brain and spinal cord. Fortunately, < 5% of people with MS have their onset in childhood years. However, studying these very-early-onset cases of MS offers key advantages. In particular, with fewer years lived, children have had a limited range of exposures, potentially enhancing our ability to identify what might cause MS. Further, as the actual timing of the biological MS onset is unknown, the possibility to study these children much closer to the real onset of disease is far greater than in the typical adult with MS. Whether MS (in children or adults) can be prevented is unknown and the available drugs are only modestly effective in modifying the disease course and are not without risk. Emerging evidence is providing insight into the gut microbiota's potential role in triggering and shaping neurological conditions such as MS. The limited number of studies in humans with MS and absence of prior work in pediatric MS motivated the following 3 fundamental questions, addressed in 2 cross-sectional and 1 longitudinal investigation in children with and without MS: 1) Does the gut microbiota composition differ between children with and without MS? 2) Is there an association between the gut microbiota and host immune markers in children with and without MS? 3) Is the gut microbiota associated with the future risk of a MS relapse?
Keywords: 16S rRNA; Case–control; Cross-sectional; Disease-modifying drugs; Longitudinal; Metagenomics; Microbiome; Microbiota; Multiple sclerosis; Pediatric; Relapse risk; Relapsing-remitting.