Mucosal Thrombin Alters Gut Microbiota Biofilms Structure And Promote Dispersion Of Bacteria With Aggressive Behavior
Bibliographic record
Abstract
Alterations of gut microbiota have been implicated in a broad variety of intestinal diseases. The mechanisms whereby this may occur remains elusive. Gut mucosal microbiota is naturally organized as a polymicrobial biofilm, separated from the intestinal epithelium by a sterile mucus layer. We recently discovered that intestinal epithelium releases active thrombin, which plays a key role in segregation of intestinal biofilms from host tissue. Furthermore, we detected an upregulation of active thrombin in inflamed human patients and in models of colitis. Objectives Our study objective was to determine whether exposure to high thrombin, such as this occurring during inflammation, will alter commensal microbiota biofilms and promote the dispersion of bacteria predisposed to damage the intestinal epithelium. Methods Microbiota extracted from healthy human colon biopsies were seeded into the Calgary Biofilm Device and polystyrene coupons to develop, a multispecies anaerobic biofilm. Biofilms were exposed to various concentrations of thrombin (10 to 1000 Unit/ml). Dispersed bacteria released from thrombin‐treated biofilms were collected and their composition was assessed by 16S sequencing. These bacteria were apically exposed to human epithelial monolayers on transwells (Caco2 and HT29MTX). Adhesion (90 minutes), invasion (gentamicin assay, 3 hours) and translocation (4 hours) to basolateral side was quantified by plating on agar. Transwells were processed for fluorescent in situ hybridization for bacteria staining and phalloidin antibody for host cell cytoskeleton. Motility phenotype of biofilmdispersed bacteria was assessed on soft agarose gels (swarming and swimming). Mice (B6) were treated intracolonically with thrombin (5U per day for 10 days) or boiled thrombin (similar dose). Rats (Wistar) were treated with TNBS to induce colitis, and were treated for 3 days intracolonically with dabigatran (thrombin inhibitor, 1 μg/kg) or vehicle. Results Biofilm‐dispersed bacteria from thrombin‐treated biofilms attached more importantly to the epithelial monolayers compared to untreated biofilm. 3D reconstruction images confirmed such thrombin‐induced phenotype. Thrombin alters swarming and swimming motility in soft agarose gel. 16S analysis further precise the specific composition of biofilm‐dispersed bacteria after thrombin exposure. In mice, intrarectal administration of thrombin caused alterations of gut microbiota biofilms structure (16S sequencing) and organization ( in situ imaging of gut microbiota). During colitis in rats, local inhibition of thrombin activity prevented gut microbiota biofilms alterations associated with colitis (in situ imaging of gut microbiota and 16S analysis). Conclusions These data suggest that high concentration of thrombin released at gut mucosal surface during inflammation alters gut biofilm organization and modifies the phenotype of biofilm‐dispersed bacteria, which were able to invade and cross the epithelial barrier, thus increasing their likelihood to trigger inflammatory flares.
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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 | 0.001 |
| 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".