The Role of Pathogenic Microbes and Commensal Bacteria in Irritable Bowel Syndrome
Bibliographic record
Abstract
BACKGROUND: Irritable bowel syndrome (IBS) reflects several pathogenetic entities including a subgroup with low-grade colonic inflammation. We propose that pathogenic bacteria act as triggers and that disturbances of commensal bacteria maintain low-grade inflammation, that in turn leads to dysfunction in the gut or brain. METHODS: Studies were performed in mice under specific pathogen-free conditions. Visceral pain was assessed by the visceromotor response and motility was assessed by in vivo fluoroscopy and in vitro by muscle contractility. Brain chemistry was assessed by in situ hybridization and behavior by standard tests. The microbiota was monitored using 16s-based RT-PCR and DGGE. RESULTS: Mice transiently infected with the nematode Trichinella spiralis exhibited changes in motility and in visceral perception that persisted for up to 6 weeks post-infection. This was accompanied by alterations in the microbiota and an upregulation of cyclooxygenase-2 which could be reversed by treatment with anti-inflammatory agents or selected probiotics. To investigate the contribution of the microbiota, we treated mice with oral antibiotics and monitored visceral perception and behavior. Antibiotic therapy produced substantial changes in the microbiota, a small increment in inflammatory activity and an increase in substance P or pain perception. Oral, but not systemic antibiotic treatment, produced changes in brain chemistry and an increase in anxiety-like behavior. CONCLUSION: These studies provide proof of concept that pathogenic microbes can induce persistent gut dysfunction and that changes in microbial composition of the gut can maintain gut dysfunction as well as induce behavioral changes reminiscent of the psychiatric comorbidity that occurs in up to 60% of irritable bowel syndrome patients.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".