Fecal Microbiota and SCFA signatures are not consistently related to Symptom Severity in Irritable Bowel Syndrome: A longitudinal study
Objectives: To assess longitudinal dynamics of fecal microbiota and short chain fatty acids (SCFAs) in different Irritable Bowel Syndrome (IBS) severity groups, and study the association with stool pattern, diet, depression, anxiety and quality of life (QoL).Methods: A longitudinal study was performed, including n=91 IBS patients and n=28 matched controls. All participants collected fecal samples and completed validated questionnaires regarding IBS severity, stool pattern, depression, anxiety and IBS-QoL at two timepoints with four weeks in-between. Diet was assessed at the first timepoint. Fecal microbiota composition was determined by sequencing the V4 region of the 16S ribosomal RNA gene, whereas SCFAs were analyzed by High-Performance Liquid Chromatography. Data was stratified for IBS severity (no, mild, moderate and severe symptoms).Results: Over time, 36% of IBS patients changed in severity groups, and 53% changed in predominant stool pattern. Microbiota alpha and beta diversity, and SCFAs did not consistently differ between IBS severity groups, nor between IBS and controls. Relative abundances of Bifidobacterium, Terrisporobacter and Turicibacter consistently differed between IBS and controls, but not between IBS severity groups. Large dynamics over time were observed in the proportion of explained variation of microbiota composition by questionnaire data, such as symptom severity and predominant stool pattern. Conclusions: Fecal microbiota and SCFA signatures were not consistently associated with IBS severity over time, indicating the importance of repeated sampling in IBS research. Remarkably, relative abundances of Bifidobacterium, Terrisporobacter and Turicibacter were consistently different between IBS and controls, indicating an interesting direction for future research.