Psychological stress, intestinal microbiome and Irritable Bowel Syndrome

Objective:

Irritable Bowel Syndrome (IBS) is associated with alterations along the brain-gut-microbiota axis. Previous studies have suggested a parallel segregation of microbial features with psychological burden in IBS. The study aimed at examining microbial correlates of psychological distress, anxiety and depression.

Design:

16 s rRNA faecal microbial analyses (hypervariable regions V1 – 2 amplified from total DNA, paired end, Illumina MiSeq) in 48 IBS patients (Rome-III criteria, mean age 42 years, 35 female subjects, 25 diarrhoea-dominant, 5 constipation-dominant and 18 alternating-type IBS). Assessment of psychological and clinical variables with validated questionnaires. Microbial analysis via QIIME, taxonomic analysis by correlation and between subgroups defined by thresholds in psychological variables.

Results:

Thirty-one patients (65%) showed psychological distress, twenty-two (31%) anxiety, and ten depression (21%). Microbial beta diversity was significantly associated with distress (FDR_p = 0.045) and depression (FDR_p = 0.034). Depression correlated inversely with Lachnospiraceae family (rho =-0.58, FDR_p = 0.018), anxiety with genus Anaerotruncus (rho = 0.65, FDR_p = 0.001), and IBS severity with genera Ruminococcus (rho = 0.62, FDR_p = 0.005) and Coprococcus (rho = 0.59, FDR_p = 0.013). Patients exceeding thresholds of distress, stress perception and depression showed significantly higher abundances of Proteobacteria (phylum to family level, LDA 2.2 – 2.5). Patients with anxiety were characterized by higher abundances in Bacteroidetes members (families Bacteroidaceae LDA = 3.0, Rikenellaceae LDA = 2.8).

Conclusion:

Psychological variables had a high discriminative value for gut microbial composition, underscoring the role of brain-gut-microbiota interaction in IBS.

Supported by Austrian Society of Gastroenterology and Hepatology (ÖGGH) and funds of the Oesterreichische Nationalbank, Fund project number: 16506.