Identification of Gut Microbiota and Metabolites Signature in Patients With Irritable Bowel Syndrome

Abstract

Background and Aims: Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder. However, the underlying mechanism of IBS is not fully understood. The aim of this study was to investigate potential mechanism and novel biomarkers of IBS through evaluation of the metabolomic and microbiologic profile.Methods: Fecal samples were collected from 15 irritable bowel syndrome patients and 15 healthy controls. By using gas chromatography coupled to time-of-flight mass spectrometry (GC-TOFMS) and 16S rDNA amplicon sequencing, fecal metabolites and microbiota of healthy controls and the IBS patients were measured.Results: IBS patients had a significantly differential metabolite profile as compared to healthy controls, and 4 clusters with 31 metabolites, including a group of amino acids and fatty acids, were significantly up-regulated as compared to the healthy controls. In addition, 19 microbes were significantly up-regulated, and 12 microbes were down-regulated in the IBS group, when compared with the healthy controls. Some clusters of fecal metabolites or microorganisms were significantly correlated with the severity of IBS symptoms, such as the frequency of abdominal pain/discomfort and the number of bowel movements. Correlation of the metabolite levels with abundances of microbial genera showed some statistically significant metabolite-microbe associations. Four differentially abundant amino acids clustered together were positively correlated with some microbes, including Lachnospira, Clostridium, and so on.Conclusion: The finding of this study puts a global perspective on metabolomics and microbiota profiling in IBS patients and provides a theoretical basis for future research on pathophysiology of IBS.

Microbial and metabolomic profiles in correlation with depression and anxiety co-morbidities in diarrhoea-predominant IBS patients

“…From the perspective of bacterial taxonomic alterations, most high-throughput data showed a decreased abundance of phyla Firmicutes and increased Bacteroidetes in IBS microbes in agreement with our results [21,24]. Vast studies demonstrated that Bifidobacterium and Lactobacillus were less abundant in IBS-D, whereas Clostridium, Escherichia coli and Enterobacter were often increased [19,20,[24][25][26]. Faecalibacterium (or F. prausnitzii) abundance in IBS increased in some studies [27], but constant or decreased in others [24].…”

“…Our current study compared the faecal microbiota from IBS-D and healthy groups. Simpson index demonstrated decreased faecal biodiversity, whereas Ace and Chao indices showed higher microbial richness in IBS-D group, supported by human and animal researches [17][18][19]. Analysis of similarity (ANOSIM), PCoA and hierarchical clustering analysis based on Bray-Curtis distance showed no significant difference of β-diversity between groups.…”

“…[26,45]. In contrast, non-targeted metabolomics approaches under development collected more detailed and global metabolic profiling data concerning metabolic homeostasis and aberrance [14,19,46,47]. Growing data had demonstrated that metabolism was disturbed in IBS of animal model [48] or patients [14], whereas detected metabolites were in divergence among studies.…”

Characteristics of fecal metabolic profiles in patients with irritable bowel syndrome with predominant diarrhea investigated using 1H‐NMR coupled with multivariate statistical analysis

“…Previous studies have shown that patients with IBS‐D have comparatively higher levels of free serum tryptophan than those in HC . Phenylalanine was identified as a major fecal metabolite in IBS, and phenylalanine metabolism was the most relevant pathway influenced by IBS . Phenylalanine is liphophilic and aromatic amino acid which influence membrane diffusion and transportation .…”

Irritable bowel syndrome - risk factors, pathogenesis and treatment options

“…Results showed IBS patients had a significantly differential metabolite profile as compared to healthy controls. Some clusters of fecal metabolites or microorganisms were significantly correlated with the severity of IBS symptoms, such as the frequency of abdominal pain/discomfort and the number of bowel movements [42]. Central nervous system signals are transmitted to the gut by neuroendocrine neurotransmitters (serotonin, corticotropin-releasing hormone, cholecystokinin, and somatostatin) which are produced in the gut by immune and enterochromaffin cells to alter microbiota behavior [43].…”