A7 THE ROLE OF PROTEASE-ACTIVATED RECEPTOR-2 IN GIARDIA INDUCED DISRUPTIONS OF THE INTESTINAL MUCUS LAYER
Bibliographic record
Abstract
Disruptions of the intestinal mucus barrier have been implicated in a variety of intestinal disorders. The mechanisms behind these disruptions remain unclear. We recently demonstrated that the enteric parasitic pathogen Giardia duodenalis alters the mucus layers of the small and large intestines at least in part via Giardia cysteine proteases. We hypothesized that goblet cell function and mucus disruptions are modulated by activation of protease activated receptor 2 (PAR2), which is highly expressed through the gastrointestinal tract, and is known to regulate mucus production in the airway and stomach. We aimed to determine whether Giardia’s cysteine proteases cleave and activate PAR2 on intestinal goblet cells, leading to modulation of their mucus producing activity. The human colonic epithelial cell line LS174T was used for in vitro mucus studies. The presence of functional PAR1 or PAR2 was assessed with calcium signaling assays using the specific activating peptides TFLLRN or 2fLIGRLO, respectively. MUC2 mucin gene expression was assessed through quantitative PCR (qPCR) in LS174T incubated with either Giardia trophozoites or activating peptides, and with pre-treatment of cells with the PAR2 antagonist p2Pal-218S pepducin. qPCR was also used to measure changes in PAR2 gene expression in response to Giardia. Wild type and PAR2 deficient mice were infected with Giardia trophozoites. The thickness of the mucus layer was measured by fluorescently staining mucus with fluorescein-coupled WGA, and expression of Muc2 and Muc5ac genes were determined using qPCR. LS174T express functional and responsive PAR2, but little or no PAR1. Treatment of cells with 2fLIGRLO (PAR2 agonist), but not TFLLRN (PAR1 agonist), increased MUC2 gene expression. Incubation of cells with Giardia trophozoites also increased MUC2 mRNA production, and this increase was abolished by pre-treatment of cells with a PAR2 antagonist. Giardia decreased PAR2 mRNA in LS174T. Giardia infection increased the expression of Muc2 and Muc5ac in the colon, and increased Muc5ac expression in the jejunum of wild-type mice compared to uninfected controls. In PAR2-/- mice, Giardia infection reduced the expression of Muc5ac, but not Muc2 in the jejunum, but did not affect gene expression in the colon. Giardia infection caused a thinning of the mucus layer in wild-type mice. In contrast, the infection induced a thickening of the mucus layer in PAR2-/- mice. Using a model of Giardia infection, the findings demonstrate that PAR2 plays a significant role in mucin gene regulation and function in mice and in a human colonic goblet cell line. CCCNSERC
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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 | 0.001 |
| 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 | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".