A43 β-DEFENSINS AS MARKERS OF INTESTINAL DYSBIOSIS: THE NATURE OF CHANGES IN β-DEFENSINS IS DEPENDENT ON THE PROCESS UNDERLYING THE INDUCTION OF DYSBIOSIS
Bibliographic record
Abstract
Abstract Background Dysbiosis may be defined as a change in the microbial composition or function that results in altered host function. Defensins are antimicrobial peptides, are part of innate immunity, and are important in host defense and maintaining homeostasis. Dysbiosis is a putative mechanism underlying the expression of many functional GI disorders like Irritable Bowel Syndrome (IBS) for which no biomarkers exist. Previous studies have revealed increased β-defensin (β-Def) levels in IBS patients, most likely due to changes in the microbiota. Aims We examined the hypotheses that: 1) Changes in β-Def are dependent on the manner in which dysbiosis is induced, and that 2) the direction of the change in β-Def depends on how dysbiosis was induced. Methods We used 4 models of experimentally induced dysbiosis to determine changes in fecal β-Def and to characterize the microbiota composition before and during the induction of dysbiosis. We used: 1) an antimicrobial cocktail (AC) in water; 2) a high-fat/ high-sugar diet (HFHSD); 3) a high salt diet (HSD) that we previously showed to induce a pro-inflammatory microbiota; and 4) mild restraint stress (MRS). All studies were performed in C57/BL6 mice except studies using MRS that were performed in NIH Swiss mice. In the AC or dietary studies, we employed a one-week intervention preceded by one-week baseline and recovery periods. In MRS studies, mice comparisons were made between a control and a stressed group. Stool samples were collected every 24 hours and were assayed for fecal β-Def levels analysis by an ELISA and microbial composition by 16S gene profiling. Results Exposure to AC or dietary change, but not MRS, resulted in significant decreases in fecal β-Def. Additionally, bacterial composition and diversity profiles were different in all mice except MRS mice (control vs. MRS males: p=0.414; control vs. MRS females: p=0.96). In contrast, mice exposed to the HSD revealed a significant increase in β-Def during treatment compared to baseline in both males (p=0.025) and females (p= 0.0019). The AC mice showed the largest changes and significant correlations between changes in β-Def levels and bacterial diversity (males: p=0.013, r=0.6; females: p=0.007, r=0.6) and richness (males: p=0.0008, r=0.70; females: p=0.003, r=0.62). However, no significant correlations were found between specific bacteria and β-Def levels in the HFHSD group. Conclusions We conclude that directional changes in fecal β-Def levels are dependent on the manner in which dysbiosis is induced. The use of β-Def as a biomarker requires comparisons with baseline levels obtained during remission in order to identify dysbiosis presence in microbiota-associated chronic GI conditions like IBS. Such an approach will identify patient subgroups that may benefit from microbiota-directed therapies. Funding Agencies CIHR
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".