Microbiomes and Pediatric onset multiple sclerosis (MS): A systematic review.

Background: Gut microbiomes play a role in developing and regulating autoimmune diseases such as multiple sclerosis (MS). We designed this systematic review to summarize the evidence of the effect of gut microbiota in developing pediatric-onset MS.

Methods: PubMed, Scopus, EMBASE, Web of Science, Google Scholar, references of the references and conference abstracts were comprehensively searched by two independent researchers. The search was done on January 1^st, 2023. Data regarding the total number of patients, the name of the first author, publication year, country of origin, mean age, duration of the disease, body mass index (BMI), type of MS, Expanded Disability Status Scale (EDSS), age at disease onset and stool composition were extracted.

Results: A literature search revealed 4237 published studies. After removing duplicates, we had 2045 records for evaluation. Twenty-three full texts were evaluated, and four case-control studies remained for systematic review. Three studies were conducted in the United States and one in the Netherlands. The number of participants in included studies ranged between 24 and 68. The mean age of patients at the time of study varied between 11.9 and 17.9 years, and the mean age at the onset of the disease ranged between 11.5 and 14.3 years. Most included patients were female. The results show that median richness (the number of unique taxa identified, which was provided by two studies) was higher in controls, and also Margalef index, which was reported by one study was higher in control group than the case group. The results of two studies also demonstrated that median evenness indexes (taxon distribution, Shannon, Simpson) were higher in control groups, as well as PD index (Faith's phylogenic diversity metric).

Conclusion: The result of this systematic review (including four studies) showed disruption of the microbiota-immune balance in pediatric-onset MS cases.