bluuebunny/crossref_metadata_2025 huggingface dataset:
A24 INCREASE IN OXIDATIVE STRESS AS MEASURED BY SERUM CYSTEINE-BASED REDOX SENSING, IS ASSOCIATED WITH FUTURE RISK OF CROHN’S DISEASE.
Authors: Mu K , Dang C , Xue M , Shao J , Lee S , LI Q , Griffiths A , Steinhart A , Dieleman L , Aumais G , Panaccione R , Turpin W , Croitoru K
Published: February 2025

Background

Crohn’s disease (CD) is a gastrointestinal disorder characterized by chronic inflammation. While increased oxidative stress is observed in established CD patients, it remains unknown whether a shift in redox status is present before the diagnosis of CD and whether it is correlated with changes in immune response and microbial composition. Our hypothesis is that oxidative stress plays a role in the development of CD, and it could be detected before the diagnosis of CD.

Aims

We aimed to assess the association between the serum redox state-related indicators, specifically cysteine (reduced form) and cysteine sulfinic acid (oxidized form), quantified by mass spectrometry, with future risk of CD and if this is further correlated with markers of systemic inflammation and alterations in gut microbiota composition.

Methods

In the Genetic Environment Microbial Project, a cohort of first-degree relatives (FDRs) of CD patients was prospectively followed. Among them, we identified subjects who later developed CD, defined as pre-CD (n=69), and matched them at a 1:4 ratio with FDRs who remained disease-free (n=276). Conditional logistic regression assessed the association with future CD. Partial Spearman regression evaluated correlation with systemic inflammation, as indicated by c-reactive protein (CRP), and with changes in gut microbiota composition (determined by fecal 16S rRNA sequencing).

Results

Elevated cysteine was negatively associated with the likelihood of developing CD (Est = -1.18; p = 0.02) and negatively correlated with CRP levels (coeff = -1.04; p = 0.028). In contrast, cysteine sulfinic acid was positively associated with CD (Est = 1.15; p = 0.0004) and positively correlated with CRP levels (coeff = 1.11; p = 0.001). Specifically, their association with CD is independent of CRP levels. Three microbial risk taxa, which we previously reported to be associated with the future development of CD, were significantly correlated with cysteine sulfinic acid (p = 0.05).

Conclusions

This study is the first to report that when redox status shifts towards oxidative stress, as indicated by the level of cysteine and cysteine sulfinic acid, the likelihood of CD increases. Furthermore, these markers also correlate with early pre-clinical inflammation, as indicated by CRP levels as well as gut microbiota composition, indicating a change of gut microbiota composition when the redox status shifts towards oxidative stress.

Funding Agencies:
A25 INVESTIGATING THE ROLE OF TOLL-INTERACTING PROTEIN DURING CITROBACTER RODENTIUM INFECTION
Authors: Forneris P , Hannawayya R , Cirone K , Cobo E
Published: February 2025

Background

Diarrheal diseases are a threat to human health, being the second leading cause of death in children. Diarrheic enterocolitis can be caused by attaching/effacing (A/E) pathogens like enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC). Citrobacter rodentium (CR), a mouse A/E pathogen, mimics EPEC and EHEC infections, causing goblet cell depletion, crypt hyperplasia, and leukocyte infiltration. Autophagy, a critical immune pathway linked to goblet cell mucus secretion, is involved in the defence against CR. Toll-interacting protein (Tollip) is an intracellular mediator of autophagy and immunity, but its role in A/E infections remains elusive. This study aims to test the hypothesis that Tollip plays a protective role in CR infection.

Aims

- Assess CR infection kinetics in WT and Tollip-/- mice.

- Assess colitis in CR-infected WT and Tollip-/- mice.

Methods

Bacterial load was assessed by fecal colony forming unit (CFU) count in CR-infected WT and Tollip-/- mice. Histological damage was evaluated by scoring epithelial damage, leukocyte infiltration and crypt hyperplasia in H&E-stained distal colon sections. Apoptotic cells were identified by TUNEL. Acid and neutral mucin production was evaluated by Alcian-PAS staining. Glycosylation patterns were determined by immunofluorescence with lectins specific to sialic acid- and fucose-bound mucins.

Results

Tollip -/- and WT mice showed similar infection kinetics during the establishment and expansion phases (2-6 days post-infection (dpi)) and steady-state (7-14 dpi), with a peak of bacterial counts at 10 dpi. WT mice cleared CR by day 15, but Tollip-/- still shed bacteria by 17 dpi. The colitis grade was similar between WT and Tollip-/- mice, with marked epithelial damage at 8 dpi and increased leukocyte infiltration at 17 dpi. Scarce apoptotic cells (<4 per field) were detected in WT and Tollip-/- mice during infection. Tollip-/- showed a thinner colonic mucin barrier and less mucin-filled goblet cells at 17 dpi compared to WT mice. CR-infected Tollip-/- mice showed altered mucin glycosylation patterns, with lower fucosylated mucins in the upper crypt and lumen and increased sialic acid-bound mucins in the luminal barrier and lower crypt. The mucin barrier, goblet cells, and mucin glycosylation were similar in uninfected Tollip-/- and WT mice.

Conclusions

This study demonstrates a new protective role for Tollip, particularly during the resolution phase, as a lack of Tollip delayed the clearance of CR. This phenotype could be explained by deficiencies in the mucin layer observed in Tollip-/- mice, evidenced by lower mucin production and anomalies in mucin glycosylation. By enhancing our understanding of host-pathogen interactions during enteric infections, this research serves as a step in the development of new treatments and prevention strategies.

Funding Agencies

None
A27 THE IMPACT OF MICROBIAL-DERIVED METABOLITES ON TYPE III INTERFERON SIGNALING IN INTESTINAL EPITHELIAL CELLS
Authors: Olumade T , Lantin C , Fedorova Y , Nelson R , Ogungbola O , Fedorova O , Bording-Jorgensen M , Armstrong H , Santer D
Published: February 2025

Background

Interferons (IFNs) are key cytokines that protect mucosal barriers. There are three types – types I, II and III. Unlike types I and II, which are pro-inflammatory, type III interferons (IFN-λs) are highly expressed in the gut and exert beneficial effects such as mucosal healing and dampening inflammation in mouse colitis models. Gut microbes can directly induce IFN-λ expression and prior studies have shown that microbial-derived metabolites can upregulate IFN-λ activity in the lungs. However, much less is known about the role of gut microbial-derived metabolites in the regulation of IFN-λ activity in the gut.

Aims

We hypothesized that specific gut microbial-derived metabolites upregulate IFN-λ activity in human gut epithelial cells.

Methods

Caco-2 cells were pre-treated for 2 hours with anaerobic whole microbe secretions (1-10% v/v) and microbial-derived metabolites, including short-chain fatty acids (SCFAs; acetate, butyrate, and propionate), a metabolic intermediate (succinate), and a tryptophan metabolite (kynurenine). Next, cells were treated with or without IFN-λ3 (20-50ng/ml) for 22 hours (n=3 biological repeats). IFN-stimulated genes (ISGs; MX1 and IFIT1) were quantified by RT-qPCR. IFN-λR1 levels were quantified by flow cytometry.

Results

Out of microbe secretions added from four gut microbes thus far, secretions from one pathobiont inhibited IFN-λ activity. All SCFAs tested had a concentration-dependent inhibitory effect on IFN-λ3 induction of ISGs (MX1 and IFIT1; p<0.05). Succinate and kynurenine did not affect ISG induction by IFN-λ3 at any concentration tested. Only specific metabolites affected surface IFN-λR1 levels on Caco-2 cells.

Conclusions

Our findings demonstrate that specific microbial-derived metabolites can regulate intestinal IFN-λ immune responses. Contrary to our hypothesis, some metabolites can downregulate IFN-λ activity. Knowledge from this study provides fundamental knowledge about IFN-λ regulation in the human gut with implications for how to promote optimal IFN-λ activity to promote gut health, such as in inflammatory bowel diseases.

Funding Agencies

Children’s Hospital Research Institute of Manitoba, University of Manitoba
A29 A NOVEL INTERACTIVE COMPLEX BETWEEN TP53, SIRT1 AND HNF4A2 IN INTESTINAL EPITHELIAL CELLS
Authors: Herrera Pulido J A , Jones C , Boudreau F
Published: February 2025

NOT PUBLISHED AT THE AUTHOR’S REQUEST

Funding Agencies:
A31 IS AN ORAL SODIUM SULFATE SOLUTION MORE EFFECTIVE FOR PATIENTS WITH PRIOR CHALLENGING COLONOSCOPY PREPARATION? - A PROSPECTIVE CASE SERIES
Authors: Khan A , Rai M , McKay J , Mohanna R , Hookey L
Published: February 2025

Background

A considerable proportion of patients encounter difficulties with existing bowel cleansing regimens for colonoscopy resulting in suboptimal bowel visualization. This impacts patients, endoscopists, those on the waiting list, and the endoscopy unit overall.

Aims

Oral Sulfate Solution (OSS) has been proven to be efficacious in many situations and therefore this study aims to explore its benefit in patients who had challenging preparations during their previous colonoscopy.

Methods

This prospective case series was conducted at Kingston Health Sciences Centre. Patients scheduled for outpatient colonoscopy were considered for enrolment if previous colonoscopy reports indicated criteria of suboptimal preparation. Participants were allowed a light breakfast the day before the colonoscopy and consumed the first dose of OSS in a split dose fashion. The primary outcome was adequacy of bowel preparation using the Boston Bowel Preparation Scale (BBPS), defined as an overall score greater than 6, with each segment scoring at least 2. Secondary outcome measures included time to cecum, volume suctioned, and tolerability rating.

Results

A total of 120 patients with colonoscopies that were deemed as challenging to prepare were included in this study. Inclusion criteria for 109 of these patients was documentation of extensive washing and suctioning for adequate view of the colon, 5 had poor or fair preparation with images revealing obvious debris and 6 either vomited or consumed 80% or less of the preparation. Participants mean age was 67 years (SD=7.151), 66 (55%) were male and 24 (20%) had diabetes. The average BBPS score was 7 (SD=1.757) and 88% of the patients had adequate preparation. Participants’ prior colonoscopy preparations were primarily polyethylene glycol (52.5%) and a picosulfate based agent with bisacodyl (40.8%). Mean time to cecum was 7 minutes and 29 seconds (SD= 4 minutes and 29 seconds). The mean total volume suctioned was 1048.78mls (SD= 708.621). Tolerability data demonstrated 107 (89.2%) participants cumulatively rated OSS overall as tolerable, easy or very easy to use. Nausea was reported by 46 participants (38.3%), while vomiting occurred in 10 (8.3%). Abdominal distension or bloating was noted by 34 participants (28.3%), and 51(42.5%) experienced abdominal cramping, discomfort, or pain.

Conclusions

OSS showed a reduction to 12% inadequate bowel preparation. This is very encouraging given this group of patients had challenging preparation in the past. Its combination of effect, ease of use, and tolerability could deem it superior to traditional choice in these patients and can be used as a standard low volume preparation.

Funding Agencies

Pendopharm
A39 IMPACT OF AN ENDOSCOPIC OPTICAL DIAGNOSIS COURSE ON GASTROINTESTINAL NEOPLASM CHARACTERIZATION SKILLS AMONG TRAINEE ENDOSCOPISTS
Authors: Tran W , Gimpaya N , Khan R , Walsh C , Hookey L , Rai M , Grover S , Bechara R
Published: February 2025

Background

Real-time endoscopic optical diagnosis involves detailed visualization of the digestive mucosal and microvascular pattern, allowing for prediction of histology. This is advantageous as it can guide endoscopic resection decisions, surgical referrals and provide cost savings to histopathology. There is, however, no standardized or widely implemented curriculum for endoscopists or trainees to learn optical diagnosis skills.

Aims

To evaluate the impact of a course for the optical diagnosis of esophageal squamous cell carcinoma (ESCC), early gastric cancer (EGC), Barrett’s esophagus (BE), and colorectal polyps

Methods

19 gastroenterology trainees were invited to the 2-day course in Kingston, Canada. Number of procedures previously performed was recorded. The impact of the course on lesion diagnosis accuracy was evaluated using a pre-test, immediate post-test, and delayed post-test administered 6 weeks after the course. A repeated measures ANOVA was performed to compare the mean score (%) between the three tests.

Results

13 trainees completed all the tests (Table 1). Mean score % values for the overall tests and test scores for esophageal, gastric, and colon lesions were summarized on Table 1. The repeated measures ANOVA determined that the mean score % had a statistically significant difference between the three tests (F (2,24)=5.63, P=0.01). Pairwise comparisons revealed that there was a statistically significant increase in mean scores between pre- and post-tests (13.86 (95% confidence interval (CI) of 4.36 to 23.33), p<0.01) with no significant difference between post and delayed post-tests (8.46 (95% CI of -0.12 to 17.04), p>0.05) (Figure 1). The mean correct % from the delayed post-test was higher than the pre-test but there was no statistical significance (5.39 (95% CI of -3.72 to 14.49), p>0.05).

Conclusions

This novel optical diagnosis course improved trainee accuracy in diagnosing ESCC, EGC, BE and colorectal polyps. Learning retention was evident, with no significant score difference between immediate and delayed post-tests. This study was limited by the low sample size and low number of test items. Further investigation is required to validate the course for international trainees and explore its clinical transferability.

Demography and Mean Score %

Figure 1. Mean score %. (*) denotes p<0.05.

Funding Agencies

None
A41 OUTCOMES FROM ESOPHAGEAL STENT PLACEMENT FOR REFRACTORY BENIGN ESOPHAGEAL STRICTURES
Authors: Yau M , Donnellan F , Byrne M F , Gan S , Trasolini R
Published: February 2025

Background

A benign esophageal stricture (BES) is an esophageal narrowing that causes dysphagia in the absence of inflammation. First-line treatment for BES is esophageal bougie or balloon dilation. Esophageal stent placement is a treatment option for refractory benign esophageal strictures (RBES) but comes with significant complication risks.

Aims

We aim to assess complications following esophageal stent placement for RBES and whether there are differences in migration rates depending on the stent length, stent width, and presence of clip or suture fixation.

Methods

This is a retrospective cohort study of adult patients with RBES who were treated with esophageal stent placement at the Vancouver General Hospital, Vancouver, Canada between Jan. 1st, 2016 and Aug. 20th, 2024. We excluded patients with malignant esophageal strictures and esophageal leakages. Data was manually extracted via patient chart review.

Results

12 patients received a total of 32 esophageal stents for RBES. 50.0% of patients had peptic strictures. 33.3% of patients had anastomotic strictures post-esophagectomy. Other causes included Barrett’s esophagus and brachytherapy. Patients received on average 7 dilations before their first stent placement. Average stent indwell time was 157 days. All stents were fully covered and metal. The average number of stents placed was 3. The average number of adverse events was 4. 87.5% of stents led to adverse events. 53.1% (17 of 32 stents) of stents migrated. 12.5% (4 of 32 stents) of stents caused granulation tissue. Stent ingrowth occurred in 6.25% of stents placed (2 of 32 stents). Other adverse events included gastrointestinal bleed, ulcers, food obstruction, dysphagia, odynophagia, chest pain, and abdominal pain. 33.3% of patients required hospitalization from adverse events. No deaths or critical care stays occurred from adverse events. 25.0% of stents were fixed with clips, padlock clips, or sutures. Risk of migration did not statistically differ between fixation and no fixation (50.0% vs 54.2%, p>0.05). Short (less than 12cm) and wide stents (greater than 18mm) were less likely to migrate as compared to long and narrow stents (52.0% vs 57.1%, p<0.05; 42.9% vs 62.5%, p<0.05; respectively).

Conclusions

Esophageal stent placement is an appropriate treatment for RBES. Although adverse events occurred in most stents placed, most were mild and manageable with appropriate counselling and intervention. No adverse events occurred leading to death or critical care stay. Guidelines from the European Society of Gastrointestinal Endoscopy recommend a maximum indwell time of 12 weeks, but in select circumstances longer indwell times are possible.

Funding Agencies:
A43 TOPICAL HEMOSTATIC AGENTS: A POTENTIAL BREAKTHROUGH IN MALIGNANCY-RELATED GI BLEEDING? A SYSTEMATIC REVIEW AND META-ANALYSIS OF RANDOMIZED CONTROLLED TRIALS
Authors: Minhas G S , Bukhari A , Yuan Y , Leontiadis G , Laine L , Barkun A , Tse F
Published: February 2025

Background

Malignancy-related gastrointestinal bleeding (GIB) has been challenging to treat with conventional endoscopic techniques. Topical hemostatic agents (THAs), which do not cause mucosal injury and can be applied over large surface areas, may offer a promising solution in cancer-related GIB.

Aims

To assess the effectiveness and safety of THAs in malignancy-related GIB compared to conventional endoscopic techniques.

Methods

We conducted a systematic review using MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials until March 2024. RCTs that compared THA vs conventional endoscopic techniques in malignant GIB were included. Two authors conducted study selection, data extraction and quality assessment independently. The primary outcome was 30-day further bleeding. Further bleeding is a composite outcome of failure to achieve immediate hemostasis and rebleeding. Secondary outcomes included failure to achieve immediate hemostasis, 6-month mortality, 30-day rebleeding, blood transfusions needed, length of hospitalization, and adverse events. RevMan 5.4 was used to calculate pooled risk ratios (RR) with 95% confidence intervals (CI, random effects model). Heterogeneity was assessed by Chi 2 (P<0.15) and I 2 tests (>25%). We assessed the certainty of evidence (CoE) for each outcome using the GRADE approach.

Results

Results: We identified 5100 citations and 4 RCTs with 122 patients were included in the analysis. There was no significant difference between THA and conventional endoscopic methods with respect to 30-day further bleeding through THAs reduce the risk of immediate hemostatic failure. There was no significant difference noted in 30-day rebleeding. THAs did not significantly impact 6-month mortality or blood transfusions. THAs were found to increase the average length of hospitalization by 4.28 days.

Conclusions

TC-325 appears superior to conventional endoscopic techniques in achieving immediate hemostasis for malignancy-related

GIB. It may reduce further bleeding over 30 days as well, but the evidence is very uncertain and further research is needed to assess bleeding risk over this period and beyond. TC-325 did not appear to reduce 6-month mortality.

Table 1. Summary of Findings

Forest plot of further bleeding

Funding Agencies:
A44 ENDOSCOPISTS PERFORMING ADVANCED UPPER GI ENDOSCOPY ARE AT HIGHER RISK OF FACIAL BACTERIAL CONTAMINATION
Authors: Baeg M , Ko S
Published: February 2025

Background

Gastrointestinal (GI) endoscopy has been recognized as putting endoscopists at risk for bacterial exposure. However, whether longer, more advanced procedures such as endoscopic submucosal dissection (ESD) or endoscopic retrograde cholagiopancreatography (ERCP) confer greater risk has not been investigated.

Aims

This study aimed to investigate the degree of exposure on endoscopists who performed ESD or ERCP and find out if longer time or procedure type are risk factors for exposure.

Methods

This was a prospective study examining the facemasks of endoscopists who performed ESD or ERCP at a university hospital, with 40 procedures planned for each procedure. The face shield was swabbed in a standardized way before and at the end of the procedure. Swabs were also taken from face shields placed 2 meters away on the endoscopy suite wall, patient recovery room wall, and after direct contamination by the endoscope immediately after the procedure. The swabs were cultured for 48 hours, and growth was reported as no growth or by number of colony-forming units (CFUs). The groups were compared for +CFU rate. Risk of contamination was analyzed by procedure time and type.

Results

55 ESDs and ERCPS were performed during the study dates. It was decided to terminate the study early, due to the COVID-19 situation, as facemasks were deemed too important to be used for walls. Excluding one facemask group in which the endoscopist’s facemask was exposed before the procedure, 54 groups of masks were analyzed. There were 33 ESDs and 21 ERCPS performed, with 26 upper GI and 7 lower GI ESDs. A cut-off of 30 CFUs were determined as indication of definite exposure. Interestingly, none of the 7 lower GI ESDs resulted in any exposure, so it was decided to analyze only the 47 orally inserted procedures. There were 9 positive exposures, 6 ESDs (23.1%) and 3 ERCPs (14.3%). Mean procedure time was 30.3 ± 15.2 minutes. Procedure time (Odds ratio 1.014, 0.968-1.061, P=0.564) and type (ERCP compared to ESD, OR 0.556, 0.121-2.553, P=0.556) were not positive risk factors for contamination. The most commonly cultured pathogens were Staphylococcus, Streptococcus, Bacillus, and Moraxella species.

Conclusions

This study confirmed that advanced procedures such as upper GI ESDs and ERCPs have a high risk of facial exposure. Facemasks and other protective equipment should be used during GI endoscopy.

Basic Characteristics of Endoscopy

ESD - endoscopic submucosal dissection, ERCP - endoscopic retrograde cholangiopancreatography

Funding Agencies

None
A49 PROSPECTIVE PAIRED COMPARISON STUDY OF 2 FRANSEEN-TIP EUS FNB NEEDLES, FLEXIBLE VS STIFF SHEATH
Authors: Borahmah F , Motomura D , Trasolini R
Published: February 2025

Background

Variety of needle tips and suction techniques have been trialled to optimize diagnostic yield in EUS-FNB for comprehensive histopathological analysis with some studies suggesting improved performance with franseen tip needle

Aims

Obtain an objective comparison of diagnostic yield between 2 different 22g franseen-tip needles; novel flexible sheath (FS) franseen tip needle and traditional stiff sheath (SS) needle

Methods

Sample of patients presenting for outpatient elective EUS-FNB were selected.

Underwent EUS-FNB using both a SS and FS FNB needle during same procedure.

Equal number of passes was obtained with each needle by same endoscopist with random order of sampling, with a planned number of 2 passes per needle; not obtained for one lesion due to difficulty with puncture.

Obtained specimens were sent to pathology; quality of sampling was assessed by the pathologist and cellularity was recorded as a percentage.

In procedures where one needle was unable to puncture or an acellular specimen was obtained a score of 0 was given.

Paired 2 tailed t-test was performed for comparison of mean cellularity. Hazard ratio was calculated for risk of obtaining a non-diagnostic sample

Results

SS mean cellularity 45.7% SD 25.7

FS mean cellularity 72.9% SD 17.0

Difference in mean cellularity 27.2% two-tailed p-value=.08

Hazard ratio of obtaining a non-diagnostic sample with SS: HR 5 p=0.28

No statistically significant difference in results but a numerical trend is noted.

Analysis demonstrates variability in cellularity of specimens obtained with each needle type; 6/8 specimens showed higher cellularity with FS needle while only 1/8 showed higher cellularity with SS.

In 2 cases, both similar lesion types in different patients, non-diagnostic specimens were obtained by SS. One patient due to inability to puncture and in a second due to inadequate cellularity

Conclusions

Results may suggest presence of tissue characteristics or lesion-specific factors that influenced the sampling efficacy.

Findings can provide potential insight into optimizing selection of biopsy needle designs and is a novel look at an uncommonly analyzed aspect of FNB needle design, namely sheath stiffness.

Several limitations of this study, primarily the small sample size

Further research with larger cohorts is needed to compare the diagnostic yields of needle types.

Despite preliminary nature of these results, this study contributes real world paired comparison data

Funding Agencies:
A53 NOVEL PROTEASE–HISTAMINE INTERACTIONS POTENTIATE PAIN SIGNALING EVOKED BY FECAL SUPERNATANTS FROM IBS PATIENTS
Authors: Jimenez Vargas N , Gilmour D A , Sokrat B , Bennett A S , Lomax A E , Reed D E , Bunnett N W , Vanner S J
Published: February 2025

Background

Proteases and histamine, originating from intestinal tissue and/or the microbiota, have each been implicated in the severe pain symptoms reported by patients with irritable bowel syndrome (IBS). However, the effects of their combined signaling and the mechanisms involved have not been studied.

Aims

To determine whether histamine and trypsin synergistically enhance colonic nociceptive signaling and, if so, to study the mechanisms involved.

Methods

Fecal supernatants (FS) were obtained from IBS patients with low and high pain scores. Responses to luminal application of FS, histamine and protease (trypsin) and antagonists (H1R-pyrilamine, PAR2-GB83) were studied using ex vivo mouse colonic afferent nerve recordings. In mechanistic studies, excitability of isolated mouse dorsal root ganglia (DRG) neurons was measured using patch clamp recordings of rheobase after combined or sequential application of agonists. To study endosomal signaling, neurons were incubated with clathrin inhibitor, pitstop2, before agonists. Using HEK cells, recruitment of mGαq to PAR2 and H1R at the plasma membrane (CAAX) or early endosome (Rab5) was measured using bioluminescence resonance energy transfer (BRET) in response to sequential application of increasing doses of trypsin and histamine.

Results

In colonic afferent nerve recordings, FS from IBS patients with high pain scores increased mechanosensitivity (50%; p <0.001) and this was blocked by either a PAR2 and H1R antagonist, whereas FS from those with low pain scores had no effect. Trypsin and histamine at subthreshold concentrations (30 μM) alone had no effect. However, their co-application increased afferent mechanosensitivity (46%; p <0.001); similar effects were observed in patch clamp recordings from DRG neurons (rheobase decreased 33%; p <0.05). To study the mechanism of this synergistic interaction, DRG neurons were recorded after a sequential incubation with histamine and proteases. Incubation first with histamine had no effect (p=0.55) on the subsequent trypsin-mediated PAR2 excitability but incubation first with trypsin amplified the histamine response by 42 % (p<0.01). This PAR2-mediated action was blocked by inhibitors of endosomal signaling. In keeping with these findings, BRET studies revealed that incubation first with trypsin promoted mGαq recruitment to the plasma membrane and early endosomes, whereas histamine did not.

Conclusions

Conclusion: FS from IBS patients with high pain scores caused exaggerated pain signaling from the mouse colon and was mediated by the synergistic action of histamine and proteases. Mechanistic studies revealed a novel pathway where trypsin-mediated PAR2 endosomal signaling amplified histamine-evoked pain signaling. These findings could inform future studies of IBS therapies and biomarkers.

Funding Agencies

CIHR
A55 CHRONIC STRESS IMPAIRS THE INTESTINAL CRYPTAL STEM CELL CYCLE AND PANETH CELL PROLIFERATION
Authors: BAI X
Published: February 2025

Background

The small intestine’s epithelial barrier is essential for intestinal homeostasis and host defense. It consists of epithelial cells constantly renewed by crypt stem cells and their progeny, which have different functions in the gut. Chronic stress can impair the barrier by modulating the gut-brain axis, which involves the hypothalamic-pituitary-adrenal (HPA) axis, the vagus nerve, and the immune system. Chronic stress can also alter the gut microbiota, further influencing the barrier and immune system.

Aims

The present study examines how chronic stress affects the crypt stem cell niche and function in the small intestine.

Methods

Restraint stress was applied to 6-8 weeks-old mice in a plastic container for 1 hour daily for 7 days. The dark/light transition box test evaluated stress-induced behavior change. The Ussing chamber technique was used to assess the paracellular permeability of the small intestine. RNA was extracted from the mucosa and submucosa layers of the small intestine, after removing the muscle layer, and RNA sequencing analysis was performed. Immunofluorescence analysis was also performed on the small intestinal tissues to detect the expression of various markers. To assess the in vivo effect of cortisol, dexamethasone (a synthetic steroid activating the same receptors as cortisol), or metyrapone (an 11β-hydroxylation blocker to inhibit cortisol production), was applied. To assess the possible involvement of microbiota, antibiotics were applied before and during the restraint stress.

Results

We found that restraint stress-induced anxiety-like behavior, increased small intestinal epithelial permeability and reduced villus and crypt length in mice. RNA sequencing analysis revealed that restraint stress downregulated the markers of Paneth cells and stem cells in the small intestinal mucosa. Immunofluorescence analysis confirmed that restraint stress reduced the expression of stem cell marker Olfm-4 and proliferation markers Ki-67 and p-H3 in the small intestinal crypts. 16s rRNA analysis showed increased Streptococcus and decreased Bifidobacterium in stressed mice fecal samples. Ablation of gut microbiota by antibiotics attenuated the stress-induced downregulation of stem cell markers but did not affect the Paneth cell markers. Dexamethasone, a synthetic glucocorticoid, mimicked the effects of restraint stress on crypt stem cells and Paneth cells, while metyrapone, a steroid synthesis inhibitor, attenuated both.

Conclusions

Chronic stress induces anxiety, gut microbiota alteration, and barrier dysfunction. The change in epithelial villi and crypts in the small intestine is in a microbiota-dependent manner. These findings show how chronic stress impacts intestinal epithelial renewal and differentiation, which may affect intestinal health and disease.

Funding Agencies

JSPS KAKENHI
A59 IMPACT OF ISOVALERATE SUPPLEMENTATION ON MURINE ANTIBODY RESPONSES DURING ENTERIC HELMINTH INFECTION
Authors: Norton N J , Lane J M , FitzPatrick R D , Gatti D M , Jensen E L , Reynolds L A
Published: February 2025

Background

Parasitic worm (helminth) infections significantly contribute to human morbidity, with nearly one fifth of the global population chronically infected. Our lab has shown that levels of the short chain fatty acid isovalerate are increased during a murine intestinal helminth infection and that isovalerate supplementation increases helminth fecundity, implying increased worm fitness.

Aims

Our research aims to elucidate the potential immunomodulatory impact of isovalerate during enteric helminth infection.

Methods

Using the small intestinal-colonizing mouse roundworm, Heligmosomoides polygyrus (Hp), to model enteric helminth infections, we examined the influence of isovalerate supplementation in the drinking water on total and Hp antigen-specific antibody responses during primary (1o) & secondary (2o) Hp infections in both sexes of C57BL/6J mice. Circulating and mucosal antibody responses were analyzed using enzyme-linked immunosorbent assays and the impact of isovalerate supplementation on lymphocyte populations was assessed in the gut-draining lymph nodes, the spleen, and Peyer’s Patches using flow cytometry.

Results

Data from one experimental repeat shows a trending reduction in total systemic and total mucosal IgA concentrations in 1oHp infected mice that were supplemented with isovalerate, compared to mice on control drinking water. In mice supplemented with isovalerate in the 2oHp infection model, one experimental repeat shows that isovalerate supplementation does not impact susceptibility to challenge infection or elicit changes to circulating or mucosal antibody levels.

Conclusions

Preliminary data suggest that isovalerate supplementation may impact total systemic and mucosal antibody concentrations during a 1oHp infection. Ongoing work includes solidifying our preliminary findings with experimental repeats. Future work will assess the impact of isovalerate supplementation on B cell development and antibody concentrations at steady state as well as during infection and elucidate the signalling mechanisms of isovalerate in vivo and in vitro. Furthering our understanding of how isovalerate affects the antibody response during a helminth infection may reveal novel immunomodulatory mechanisms in the intestine and may be applicable to other gut-restricted diseases.

Funding Agencies

CIHRTRIANGLE
A61 GLOBAL INCIDENCE OF APPENDICITIS: A POPULATION-BASED STUDY OF THE ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT
Authors: Buie E , Coward S , Buie M J , King J A , Wilson L M , Quan M , Gimon T , Kaplan G G
Published: February 2025

Background

The global incidence of appendicitis in 2019 was estimated at 228 per 100,000 person-years. However, temporal trends of appendicitis rates vary between early industrialized and newly industrialized regions.

Aims

To analyze annual appendectomy rates in regions of the Organisation for Economic Co-operation and Development (OECD) in the 21st century.

Methods

We conducted an observational population-based cohort study using data from 34 OECD regions from 2000–2023. OECD data provides country-level annual hospitalization rates for appendectomy per 100,000 person-years. We used Poisson regression to calculate Average Annual Percentage Change (AAPC) in appendectomy rates, with associated 95% confidence intervals (CI) for each region. CIs crossing 0% were defined as stable.

Results

We observed geographic variation in appendectomy incidence rates, with rates ranging from 56.8 per 100,000 in Portugal (2023) to 165.6 per 100,000 in Switzerland (2022) (Table 1). Appendectomy rates significantly decreased in 22 regions and significantly increased in 10 regions, with AAPCs ranging from −4.25% (95%CI: −4.28, −4.22) in Italy to 1.46% (95%CI: 1.23, 1.68) in Norway (Table 1). AAPCs in Iceland were stable, and Latvia had insufficient data for time trend analysis.

Conclusions

In the 21st century, time trends of appendectomy rates across OECD regions displayed variation, with the majority decreasing. Geographic variability in rates and trends over time may be due to factors such as differential access to improved diagnostic imaging and non-surgical treatments.

Table 1. The Average Annual Percentage Change (AAPC) in appendectomy for the 34 regions of the OECD dataset with the corresponding year ranges for each region, confidence intervals, and associated average incidence per 100,000 person-years. All region AAPCs are significantly increasing or decreasing except Iceland and Latvia.

Funding Agencies

None
A63 FIRST REPORTED PEDIATRIC CASES OF SEWER WORKER’S DISEASE
Authors: Swatski M D , Issenman R M
Published: February 2025

Background

Sewer worker’s disease, often recognized as a workplace hazard for sewer workers, has never been described in pediatric subjects.

Aims

We report a case series of two siblings who developed chronic nasopharyngeal discharge, sore throat, diarrhea and irritability secondary to airborne supersaturation of E. Coli from an improperly vented household septic tank.

Methods

Case Series- Retrospective Chart and Literature Review

Results

The affected subjects were a six year old boy and his three year old sister. The boy presented with chronic diarrhea. The girl presented with six to eight watery stools per day and nocturnal stooling. Parents reported that both children also had a chronic purulent nasal discharge and complained of sore throats. Her parents also endorsed anorexia along with increased fussiness. Both siblings had been treated with metronidazole for Giardia Lamblia five years earlier. Repeat examination of stool for ova & parasites was negative. CBC and D-xylose were normal. Both children underwent upper GI endoscopy. Biopsy was normal in one and diffuse duodenal inflammation was noted in the second child. A heavy growth of E. Coli was cultured from the nares of both children.

The children both slept in a basement bedroom. Their father had installed a toilet in the basement 18 months prior to their presentation. The babysitter and the patient’s grandmother both developed similar symptoms after spending prolonged periods of time in the bedroom. Their symptoms resolved when they were away from the house. The mother recalled “a sewer” smell that had been present in the basement since her husband had installed a basement toilet. Professional inspection noted that the absence of a ”stack” to properly vent the toilet which was directly connected to the home septic tank. This left the basement air supersaturated with E. Coli. All the children’s symptoms resolved after the basement toilet was removed and the related drain sealed.

It is presumed that the growth of E. Coli as well as exposure to sewer gas was responsible for their ENT and GI symptoms. Lundholm, M. et al. describe how sewer worker’s symptoms including skin disorders and diarrhea were directly related to the concentration of airborne gram-negative bacilli.

As these children’s symptoms were directly related to exposure to an improperly vented sewage system and immediately resolved following corrective action, the most likely explanation was supersaturation. This should prompt Pediatricians to take a broader environmental history, particularly when multiple patients develop symptoms which are similar in character and time of onset.

References

Lundholm, M., & Rylander, R. (1983). Work related symptoms among sewage workers. Occupational and Environmental Medicine, 40(3), 325-329.

Conclusions

When confronted with a cluster of common symptoms in uncommon places, physicians should consider the possibility of environmental diseases.

Funding Agencies

None
A71 SUBGROUP ANALYSIS OF CANADIAN PARTICIPANTS IN PUNCH CD3-OLS: A PHASE 3 OPEN-LABEL CLINICALSTUDY TO EVALUATE THE SAFETY AND EFFICACY OF FECAL MICROBIOTA, LIVE-JSLM, IN ADULTS WITH RECURRENT CLOSTRIDIOIDES DIFFICILE INFECTION
Authors: Steiner T S , Louie T , Kao D , Smyth D , Guthmueller B , Jason T , Elliott S N , Srivastava S , Lee C
Published: February 2025

Background

Fecal microbiota, live-jslm (RBL) is the first United States (US) Food and Drug Administration-approved, single-dose, microbiota-based live biotherapeutic product to prevent recurrent Clostridioides difficile infection (rCDI) in adults following standard-of-care (SOC) antibiotics. In a prospective phase 3, open-label study (PUNCH CD3-OLS; NCT03931941) conducted in the US and Canada, RBL demonstrated a 73.8% treatment success rate at 8 weeks and a 91.0% sustained clinical response rate through 6 months.

Aims

To evaluate the safety and efficacy of RBL in Canadian participants in PUNCH CD3-OLS.

Methods

PUNCH CD3-OLS participants were aged ≥18 years with documented rCDI and confirmed use of SOC antibiotics. Participants with comorbidities including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and immunocompromising conditions due to disease and/or medications were permitted to enroll. A single dose of RBL was rectally administered within 24–72h of SOC antibiotic completion. The primary endpoint was the number of participants with RBL- or administration-related treatment-emergent adverse events (TEAEs). Secondary endpoints included treatment success at 8 weeks and sustained clinical response at 6 months after RBL administration.

Results

Of the 697 participants who received RBL, 117 were Canadian. Participants in Canada were mostly White (91.5%) and female (70.1%) with a mean (SD) age of 61.3 years (17.38). Twenty participants (17.1%) were hospitalized for their qualifying episode. Participants’ medical histories included IBD (unspecified, [1.7%, n=2]; Crohn’s disease, [6.0%, n=7]; ulcerative colitis, [5.1%, n=6]), IBS (6.8%, n=8), and mild-to-moderate immunocompromising conditions (7.7 %, n=9). TEAEs through 8 weeks after RBL administration were reported by 59.8% of participants; most were gastrointestinal (48.7%, n=57) and mild-to-moderate in severity. Serious TEAEs were reported by 5.1% of participants within 8 weeks of RBL administration. At 8 weeks, 75.2% of participants (88/117) had treatment success; of those, 90.9% (80/88) had a sustained clinical response at 6 months. Demographics, safety, and efficacy outcomes were similar for participants in the US.

Conclusions

RBL was safe and efficacious for preventing rCDI among Canadian participants from PUNCH CD3-OLS, the largest study of a live microbiota-based therapy conducted to date.

Funding Agencies

NRCFerring Pharmaceuticals
A73 MICROBIAL CONTRIBUTION TO THE RISK OF FUTURE CROHN’S DISEASE: STRATIFICATION BY SUBCLINICAL INFLAMMATION LEVELS MEASURED BY FECAL CALPROTECTIN
Authors: LI Q , Turpin W , Olivera Sendra P , Xue M , Griffiths A , Panaccione R , Dieleman L , Steinhart A , Jacobson K , Lee S , Croitoru K
Published: February 2025

Background

Crohn’s disease (CD) prevalence is rising globally, but its pathogenesis remains unclear. Our group found specific microbes predict future CD risk in healthy first-degree relatives (FDR), whereas high fecal calprotectin (FCP) level (>100ug/g) was also significantly associated with a 6-fold higher risk of CD onset. However, the influence of FCP on how microbial communities contribute to CD risk remains unknown. Understanding microbial interactions with gut inflammation may offer insights into CD onset.

Aims

This study investigates how microbial composition and function contribute to CD risk in healthy in association with their baseline FCP levels.

Methods

Healthy FDRs from the CCC-GEM Project were followed for CD onset. Using baseline stool samples, microbial compositions were analyzed with 16S rRNA sequencing and functional predictions with PICRUSt2. Cox PH models assessed relationships between microbiome composition, functional pathways, and CD risk stratified by high or low levels of subclinical inflammation, defined by FCP with a cut-off of 100 ug/g (FCP>100 and FCP<100, respectively). q<0.1 was considered statistically significant.

Results

We followed 3430 FDRs for a median of 7.7 years, among which 76 developed CD. In the subgroup with FCP>100 a higher abundance of Ruminococcus torques group, an undefined Ruminococcus genus, and Romboutsia were significantly associated with an increased risk of CD. In contrast, Oscillospiraceae family was consistently associated with a lower CD risk in both FCP>100 and FCP<100 subgroups.

Microbial functional pathways analysis revealed that peptidoglycan-N-acetylmuramic acid deacetylase, 4’-phosphopantetheinyl transferase, and iron(III) transport system ATP-binding protein were consistently associated with a decreased risk of CD in both FCP>100 and FCP<100 subgroups. However, pathways including Flagellar motor switch protein FliN and Carboxynorspermidine decarboxylase were associated with increased risk of CD, but only in the FCP>100 subgroup. In contrast, geranylgeranyl diphosphate synthase and heat shock protein HspR were associated with increased CD risk in the FCP<100 subgroup.

Conclusions

The microbial contribution to CD risk in healthy FDRs may vary depending on baseline FCP levels. Specific taxa and functional pathways were identified as contributors to CD risk in FDRs in the presence or absence of intestinal inflammation. Notably, the Oscillospiraceae family was consistently associated with a decreased risk of CD, highlighting its potential as a therapeutic target in the pre-clinical phase of CD.

Funding Agencies

None
A74 IMPACT OF INDOLE-3-PROPIONIC ACID ON BACTERIAL INVASION POTENTIAL OF KLEBSIELLA STRAINS ISOLATED FROM PEDIATRIC ULCERATIVE COLITIS PATIENTS
Authors: Arjomand Fard N , Aujla H , Stuart L , Cheng C C , Elhenawy W , Perry T , Wine E
Published: February 2025

Background

Indole-3-propionic acid (IPA), a tryptophan metabolite produced by microbes, has demonstrated beneficial effects, including reversing dysbiosis, balancing bacterial populations, and reducing inflammation. However, the mechanisms behind these effects and their impact on pathogenic microbes remain unclear. This study aimed to evaluate the effects of IPA on bacterial invasion in vitro, using potential pathobionts (Klebsiella variicola and Klebsiella quasipneumoniae) isolated from non-inflamed sections of the colon in pediatric ulcerative colitis (UC) patients.

Aims

We hypothesized that IPA could reduce virulence traits, promoting a more homeostatic environment, which could lower inflammation in pediatric UC patients.

Methods

Caco-2 cells (colonic epithelial cell line) were infected with Klebsiella strains, with or without 0.5 mM IPA. Bacterial invasion was assessed via gentamicin protection assay, and qPCR measured Interleukin-8, IL-10, and TNF-α expression in infected cells. Transepithelial electrical resistance (TEER) assay evaluated barrier integrity, and qPCR analyzed the expression of bacterial virulence genes, including entB (siderophores), manC (capsule), and hcp1 (type VI secretion) in IPA-treated and untreated cultures. Additionally, siderophore production was quantified using a Chrome-Azurol Sulfonate (CAS) assay, and Anthony’s stain visualized the bacterial capsule.

Results

IPA-treated Caco-2 cells showed significantly reduced bacterial invasion, with further reductions when bacteria were also exposed to IPA. qPCR revealed a significant decrease in IL-8 expression in IPA-treated cells during infection. IL-10 levels decreased non-significantly, and TNF-α expression showed variable results. A trend toward improved tight junction integrity was observed in the TEER assay with IPA treatment, although no significant differences were detected. IPA treatment increased the expression of entB, manC, and hcp1 genes, except for K. variicola, where manC expression remained unchanged. IPA significantly reduced the capsule thickness of K. variicola and resulted in a significant reduction in K. quasipneumoniae siderophore production.

Conclusions

IPA reduces bacterial invasion and modulates immune responses in Caco-2 cells infected with Klebsiella pathobiont strains. It decreases the virulence of K. quasipneumoniae by targeting siderophore production and diminishes the virulence of K. variicola by reducing capsule formation, suggesting its potential as an anti-virulence agent against these pathobionts. These findings highlight IPA’s potential as an immunomodulatory agent for managing IBD. However, further research is needed into other Klebsiella virulence pathways and host-microbiota interactions.

Funding Agencies

CIHRWCHRI