ScopeThe gut microbiome regulates various metabolic pathways in the host and its dysbiosis is involved in the pathogenesis of diverse diseases. One of the major factors triggering gut microbiome establishment is diet. This study aims to unravel interactions and changes between diet and gut microbiome over a period of 3 years.Methods and resultsThis study investigates the relation between diet and the microbiome of 75 individuals over a 3‐year time period. Shotgun metagenomic sequencing is performed to profile gut microbial composition and function. This study shows that there are significant changes in gut microbiome taxonomy and functional composition between two time points. Whereas microbial taxonomy is found to be highly individualized, overall microbial functions stay relatively stable. Moreover, in silico metabolic modeling of microbial communities indicates that changes in dietary intake of medium‐chain saturated fatty acids is accompanied by an altered utilization of amino acids by the gut microbiome.ConclusionThe study design allows us to validate functional stability within the gut microbiome of healthy subjects over a 3‐year period. However, enduring changes in nutrition such as increased alcohol consumption or decreased intake of vegetables come along with enhanced microbial functions that are associated with disease etiology.

To elucidate cross-sectional patterns and longitudinal changes of oral and stool microbiota in multiple sclerosis (MS) patients and the effect of B-cell depletion. We conducted an observational, longitudinal clinical cohort study analysing four timepoints over 12 months in 36 MS patients, of whom 22 initiated B-cell depleting therapy with ocrelizumab and a healthy control group. For microbiota analysis of the oral cavity and the gut, provided stool and oral swab samples underwent 16S rDNA sequencing and subsequent bioinformatic analyses. Oral microbiota-patterns exhibited a reduced alpha-diversity and unique differential microbiota changes compared to stool such as increased levels of Proteobacteria and decreased abundance of Actinobacteria. Following B-cell depletion, we observed increased alpha-diversity in the gut and the oral cavity as well as a long-term sustained reduction of pro-inflammatory Gram-negative bacteria (e.g., Escherichia/Shigella). MS patients have altered stool and oral microbiota diversity patterns compared to healthy controls, which are most pronounced in patients with higher disease activity and disability. Therapeutic B-cell depletion is associated with persisting regression of these changes. Whether these microbial changes are unspecific side-effects of B-cell depletion or indirectly modulate MS disease activity and progression is currently unknown and necessitates further investigations.

Objective: To elucidate cross-sectional patterns and longitudinal changes of oral and stool microbiota in multiple sclerosis (MS) patients and the effect of B-cell depletion.Methods: We conducted an observational, longitudinal clinical cohort study analysing four timepoints over 12 months in 36 MS patients, of whom 22 initiated B-cell depleting therapy with ocrelizumab and a healthy control group. For microbiota analysis of the oral cavity and the gut, provided stool and oral swab samples underwent 16S rDNA sequencing and subsequent bioinformatic analyses. Results: Oral microbiota-patterns exhibited a reduced alpha-diversity and unique differential microbiota changes compared to stool such as increased levels of Proteobacteria and decreased abundance of Actinobacteria. Following B-cell depletion, we observed increased alpha-diversity in the gut and the oral cavity as well as a long-term sustained reduction of pro-inflammatory Gram-negative bacteria (e.g., Escherichia/Shigella).Conclusion: MS patients have altered stool and oral microbiota diversity patterns compared to healthy controls, which are most pronounced in patients with higher disease activity and disability. Therapeutic B-cell depletion is associated with persisting regression of these changes. Whether these microbial changes are unspecific side-effects of B-cell depletion or indirectly modulate MS disease activity and progression is currently unknown and necessitates further investigations.