bluuebunny/crossref_metadata_2025_split huggingface dataset:
A41 IDENTIFICATION OF MICROBIAL LYSOPHOSPHATIDYLCHOLINE (LPC) AND LYSOPHOSPHATIDIC ACID (LPA) PRODUCERS AND THEIR EFFECTS ON THE HOST
Authors: Hall-Bruce M , Pujo J , De Palma G , Mohan V , Lu J , Collins S , Bercik P 
Published: February 2024

Abstract

Background
Gut microbiota plays a key role in shaping our immune system, producing a myriad of molecules with neuro- and immunomodulatory properties. Many of these bioactive molecules are generated by bacterial metabolism of common dietary components. We have recently found that fecal samples of patients with chronic abdominal pain contain high levels of inflammatory phospholipids, lysophosphatidylcholine (LPC) and its active metabolite lysophosphatidic acid (LPA). Both phospholipids have been previously linked to genesis and maintenance of chronic neuropathic pain. In addition, they appear to have pro-inflammatory properties.

Aims
To investigate whether gut bacteria can produce LPC and LPA from dietary precursor phosphatidylcholine (PC), and whether these phospholipids can induce inflammatory responses in the host.

Methods
Fecal samples from patients with chronic abdominal pain were analyzed for microbial profiles using 16S rRNA (Illumina) analysis, and abundance of individual bacteria was correlated with fecal LPC and LPA levels as measured by ELISA. To confirm ability to produce these lipids, identified bacteria were incubated with either phosphatidylcholine (PC) or LPC (the immediate precursors of LPC and LPA, respectively) and LPC and LPA levels measured using liquid chromatography-mass spectrometry. To investigate pro-inflammatory effect of LPC and LPA, mouse splenocytes were incubated with LPC and/or LPA in vitro, and tested for cytokine production.

Results
Higher abundance of several bacterial species was associated with higher fecal levels of LPC and LPA. Among them, a bacterium from family Oscillospiraceae was identified as the most likely producer of both LPA and LPC; its abundance also correlated with high pain scores. Culturing and incubating this bacterium with PC and LPC resulted in a significant production of LPC and LPA. Additionally, LPA, but not LPC, resulted in increased levels of IL-6 production by splenocytes in vitro compared to the PBS only control. Interestingly, LPA induced IL-6 secretion was inhibited in the presence of LPC.

Conclusions
We have identified several bacterial producers of LPC and LPA, among them a bacterium from family Oscillospiraceae, which was also associated with high abdominal pain scores. LPA, but not LPC, seems to induce proinflammatory responses in the host. Further experiments are needed to identify the specific mechanisms by which these bioactive phospholipids induce abdominal pain and immune responses in the host.

Funding Agencies
CIHRFarncombe Family Digestive Health Research Institute
A43 MECHANISMS OF UNIQUE COLONIZATION DYNAMICS AND IMMUNE RESPONSES TO MURIBACULACEAE
Authors: Popple S , Pepin D , Ghezzi H , Tropini C , Osborne L 
Published: February 2024

Abstract

Background
Commercially available probiotics have a limited ability to alter the gut microbiome and establish within a pre-existing microbial community. Increases in osmolality, a condition prevalent in intestinal diseases, depletes the highly abundant bacterial family Muribaculaceae (Mb) from the gut microbiome in a mouse model of short-term osmotic laxative use. Excitingly, despite microbial community re-equilibration in its absence, Mb supersedes other bacterial colonizers to its original abundance if reintroduced, suggesting unique colonization attributes and a potential privileged immune interaction.

Aims
We aimed to investigate whether and how Mb colonization affects intestinal innate and adaptive immune homeostasis, including the generation of Mb-specific antibodies.

Methods
To examine interactions between Mb and the immune system that allows for efficient colonization, we used the osmotic laxative polyethylene glycol (PEG) to clear Mb and then generated mice with complex microbiomes that either lack Mb completely (Mb naïve) or were introduced to 8 murine-derived Mb strains (Mb+). The same strains were then introduced to Mb naïve mice (primary exposure to the immune system). To model secondary exposure, Mb+ mice were treated with PEG, and Mb re-introduced 3 weeks later. Leukocytes from the small and large intestinal lamina propria and gut-draining mesenteric lymph nodes (mLNs) were profiled over 21 days to characterize colonization and recolonization dynamics.

Results
High-throughput 16SrRNA sequencing showed no significant difference between relative abundance of Mb isolates during colonization or recolonization, indicating that Mb is capable of establishing in mice that have never been colonized with it before, making up to 20% of the relative abundance. Broad immunophenotyping demonstrated robust CD11b-CD103+ dendritic cell and Germinal Centre B cell responses in the mLNs of mice seeing Mb for the first time, yet no subsequent plasmablast accumulation in the mLN or lamina propria. We also observed significantly increased type two innate lymphoid cells in the small intestine upon primary exposure to Mb. Recolonization elicited no detectable changes in the monitored populations.

Conclusions
The lack of immune reactivity upon reintroduction to Mb suggests Mb may evade immune detection upon repeat exposure and contribute to its robust colonization abilities. Determining mechanisms involved in Mb colonization and its impact on host immune responses could increase our understanding of colonization dynamics and highlights the potential of Mb as a model for microbiota reintroduction in therapeutic applications.

Funding Agencies
Weston Family Foundation
A52 THE LGR5 ACTIVITY MODULATES CELL METABOLISM TO FAVOR WOUND HEALING
Authors: Acosta Montalvo J A , Arguin G , Dagenais Bellefeuille S , Gendron F 
Published: February 2024

Abstract

Background
The stem cell marker leucine-rich G-protein-coupled receptor-5 (LGR5) acts as an R-spondin (RSPO) signal transducer, facilitating WNT signaling to support tissue development and renewal. In GI diseases, LGR5+intestinal stem cells play a critical role in wound healing, while its expression by cancer stem cells correlates with cancer progression and chemoresistance. Surprisingly, only a handful of studies have investigated the functional role of LGR5 as a receptor. Demonstrating LGR5 receptor function and identifying signaling determinants will be a significant breakthrough in understanding stem cell biology under normal and pathological conditions. The project hypothesis is that LGR5 scaffolds the assembly of signaling complexes that modulate cell metabolism to accommodate cell fate, growth, and migration.

Aims
The project aims to characterize the molecular determinants linking LGR5 to cell metabolism and wound healing.

Methods
As a working model, recombinant LGR5 and mutant constructs were expressed in HEK293 cells. Wound healing was determined using scratch and single-cell tracking assays to measure cell migration. Cellular metabolism was measured using Seahorse assays complemented by metabolomic studies.

Results
Proteomic analysis revealed a rich LGR5 protein interactome associated with amino acid, glucose, purine metabolism, scaffold proteins (e.g., 14-3-3), and GPCR signaling. Using Seahorse assays, we showed that oxygen consumption and glycolysis were increased in LGR5-expressing cells, while metabolic profiling revealed enrichment in metabolites associated with glutamate, purine, pyrimidine metabolism, pentose phosphate pathway, glycolysis, and TCA cycle, among others. Finally, LGR5 expression promoted wound healing and a single cell's migration distance.

Conclusions
The results describe for the first time a functional role of LGR5 as a receptor, but foremost as an effector modulating cell metabolism. The findings may pave the way for new therapeutics targeting the LGR5 interactome to restore tissue homeostasis in diseases such as inflammatory bowel disease or to block cell adaptation and dissemination in the context of cancer.

Funding Agencies
CCCNSERC
A58 UTILIZATION OF HYPOXIA-TOLERANT ORGANISMS AS A MODEL IN THE STUDY OF ISCHEMIC-REPERFUSION INJURY IN TRANSPLANT HEPATOLOGY
Authors: Hossein-Javaheri N , Buck L 
Published: February 2024

Abstract

Background
Ischemic-reperfusion injury (IRI) is a barrier to successful liver transplantation. This complex process is initiated by an episode of hypoxia and decreased adenosine triphosphate (ATP) production. Mammalian hepatocytes are susceptible to prolonged hypoxia and may experience irreversible damage with ATP depletion. Yet, facultative anaerobes have developed physiological hepatoprotective strategies to tolerate hypoxic stress. The painted turtle (Chrysemys picta belli) and the common goldfish (Carassius auratus) are able to survive under severe hypoxia for weeks to months.

Aims
Introducing hypoxia-tolerant organisms as a suitable animal model for studying IRI in transplant hepatology.

Methods
A comprehensive search of PubMed, OVID, CINAHL, and Cochrane databases up to May 2023 was conducted to identify all studies reporting experimental evidence and hepatoprotective pathways in hypoxia-tolerant organisms (HTOs). Each article was qualitatively assessed. The primary focus was on cell death, intracellular ion gradient, mitochondrial function, and reactive oxygen species (ROS) with hypoxia and IRI.

Results
HTOs have increased glycogen storage with a greater ATP yield from anaerobic metabolism (glycolysis). Approximately 15-30% of liver mass in HTOs is composed of glycogen which is massive compared to 5-6% in mammals. Turtle isolated hepatocytes can tolerate 10 hours of anoxia by reducing cellular metabolic demand by 90% through decreased protein synthesis and ion channel activity. Goldfish hepatocytes can tolerate 6 hours of anoxia via similar strategies. In mammals, mitochondria undergo depolarization, Ca2+ efflux, cellular swelling, and apoptosis with anoxia. Yet, a depolarized mitochondrial membrane potential is regulated to provide cellular protection in HTOs. The ability to preserve mitochondrial function and electrochemical gradients with oxygen lack is an important contributor to cellular survival. Even in mammalian hepatocytes, if the mitochondrial integrity is maintained, cells are better able to tolerate ischemic insults. Finally, formation of radicals with reperfusion leads to hepatocyte apoptosis and necrosis in the mammalian model. Meanwhile, regulated ROS levels in turtles and goldfish cells, prevent cell death and IRI.

Conclusions
IRI is of significant interest in transplant hepatology. Although extremely valuable, the traditional mammalian models are vulnerable to hypoxia. Meanwhile, HTOs have undergone years of adaptation with thousands of genes dedicated to hypoxia tolerance. Utilizing these organisms can provide a broader understanding of IRI and avoid irreversible tissue damage in transplant hepatology.

Funding Agencies
CIHR
A60 INVESTIGATING THE ROLE OF NUCLEOTIDE-BINDING OLIGOMERIZATION DOMAIN (NOD) PROTEINS DURING BACTERIAL INFECTIONS IN INTESTINAL EPITHELIAL CELLS
Authors: Nissan M , Girardin S E 
Published: February 2024

Abstract

Background
Inflammatory bowel disease (IBD) is a collection of conditions that result in the inflammation of the gastrointestinal tract causing diarrhea, abdominal pain, weight loss, nausea, and vomiting. With its prevalence a whopping 0.6% in Canada, there is a need to understand the targets of therapy for the disease. Crohn’s disease, which is one of the two main conditions implicated in IBD, is most often associated with polymorphisms in the NOD2 gene. NOD2 is integral to the innate immune system of mammals, and functions as a pattern recognition receptor within the cytosol of cells. It detects conserved bacterial peptidoglycans to elicit an anti-microbial response by activating the nuclear factor kappa B pathway. NOD proteins also tackle infections upon bacterial recognition by recruitment of autophagy proteins allowing for the degradation of invading bacteria. Given their roles in bacterial clearance, it is unsurprising that mice deficient for NOD1 or NOD2 show increased susceptibility to pathogens, which is also what is thought to occur with Crohn's disease patients.

Aims
Although NOD1 and NOD2 have been well characterized in immune cells, little research has been done to interrogate their role during bacterial dysbiosis in intestinal epithelial cells. This research aims to elucidate the global signaling landscape that these proteins modulate in intestinal epithelial cells post-infection. We hypothesize that NOD1 and NOD2 play a critical role in host defense against intracellular bacterial pathogens in intestinal epithelial cells.

Methods
Intestinal crypts were harvested from WT, Nlrc4-/-, and Nlrc4-/- Ripk2-/- C57BL/6 mice to generate primary ileal organoids. Organoids infected with Shigella flexneri were harvested for protein and RNA. Downstream western blot, qPCR, Immunohistochemistry, and CFU analyses were performed to ensure the efficacy of the infection.

Results
Upon Shigella flexneri infection, CFU counts were only able to be recorded in a non-pyroptotic background (Nlrc4-/-). When examining the organoids by Immunohistochemistry, Shigella was well visualized in the Nlrc4-/- enteroids and was absent in WT controls 4 hours post-infection. Additionally, an increase in pro-inflammatory and stress genes was seen only in Nlrc4-/- organoids compared to WT controls. Finally, Nlrc4-/- Ripk2-/- organoids experience higher bacterial loads by CFU analysis compared to Nlrc4-/-Ripk2+/+ organoids.

Conclusions
Our research has shown that NOD1 and NOD2 deficiencies in primary mouse epithelial cells have increased bacteria loads compared to WTs upon infections showcasing a novel epithelial-intrinsic role for NOD1 and NOD2. This new insight into an epithelium-intrinsic role may be a step towards understanding the mechanism behind NOD2-associated Crohn's disease pathogenesis.

Funding Agencies
CIHRCrohn's and Colitis Canada
A70 INABILITY TO AMBULATE FOLLOWING COLONOSCOPY: AN UNEXPECTED COMPLICATION
Authors: Balbaa A , Brackenridge E , Tarnopolsky M , Sherlock M 
Published: February 2024

Abstract

Background
The peroneal nerve innervates the lower extremities. Compression injury has been documented in the adult patients following the lithotomy position perioperatively, but has rarely been described in pediatric patients following colonoscopy.

Aims
To report a rare complication following colonoscopy and discuss possible aetiologies.

Methods
A chart review of a post-colonoscopy peroneal nerve injury in a pediatric patient was conducted along with a literature review.

Results
A 12 year old boy with ulcerative colitis underwent a colonoscopy for flare symptoms. He was in the left lateral decubitus position for 60 minutes. Immediately after the procedure, he experienced loss of sensation from the left knee to the plantar aspect of the foot, and left foot drop. He had no symptoms of weakness or paresthesia in the right lower extremity or the upper extremities. Prior to the procedure, he reported normal strength, function, and sensation of all extremities. He had no history of injury, joint inflammation or previous surgery affecting his left leg. He had no recent history of steroid use or systemic illness.
Two months post procedure he had some symptom improvement and could independently ambulate. He had normal range of motion, strength, and sensation in the upper extremities and right lower extremity. His left leg had 4/5 strength on dorsiflexion and decreased pinprick and light touch sensation. He had difficulty with heel-toe walking.
Reflexes were normal.
Left leg X-ray and spine MRI were normal. Electrodiagnostic evaluation supported a left common peroneal nerve injury, predominantly demyelinating in nature with minimal axonal contribution, likely secondary to compression around the fibular head during the time of the colonoscopy. He showed full recovery and returned to baseline by 7 months.

Conclusions
Peroneal nerve injury post colonoscopy is very rare. A study focusing on pediatric colonoscopy found that 3 of 746 patients experienced postoperative neuropathies in their lower extremities. Procedure times were between 70-120 minutes. Presentations and recovery periods were variable, lasting several days to 3 months.
The mechanisms of this injury are unclear and felt unlikely to be secondary to positioning alone. It is speculated that BMI, procedure length, frog leg position and position changes, as well as systemic inflammation may be contributory. Factors such as hypothermia, dehydration, hypotension, hypoxia, and electrolyte disturbances may further place patients at risk. Awareness of this rare event and potential modifiable risk factors is important.

Funding Agencies
None
A73 EVALUATING MENTAL HEALTH CONDITIONS IN YOUTH WITH INFLAMMATORY BOWEL DISEASE: A RETROSPECTIVE STUDY
Authors: Beaudoin K , Mewhinney E , Lo J , Halder S , Bortolin K , Dowhaniuk J , Issenman R , Pai N , Sherlock M , Zachos M , Grant C , Beattie K , Prowse K 
Published: February 2024

Abstract

Background
Adolescents with chronic disease are at increased risk of psychosocial and socio-emotional challenges. During and after the COVID-19 pandemic, an increased prevalence of mental health conditions was observed in youth with chronic conditions. It is essential to understand the prevalence of mental health conditions in youth with Inflammatory Bowel Disease (IBD) to better support, advocate, and treat mental health conditions within a pediatric healthcare setting.

Aims
We aimed to determine the number and proportion of patients with IBD at McMaster Children’s Hospital (MCH) whose medical charts have documentation of 1) a mental health condition (generalized anxiety disorder (GAD), social anxiety disorder (SAD), eating disorder, major depressive disorder (MDD), suicidal ideation, attention deficit disorder and other) and/or 2) medication(s) used to treat mental health conditions.

Methods
Patients 12-17 years old with IBD who were treated in the pediatric Gastroenterology Clinic at MCH and had at least one appointment since June 4, 2022 were eligible. Medical records were reviewed to identify documented mental health conditions and patients’ current medications. The prevalence was then determined.

Results
Of 114 patients (77 male) (mean (SD) age 15.1 (1.6) years old), 33 (29%, n=20 males) had ≥ 1 recorded mental health condition: GAD (n=27, 82%), SAD (n=1, 3%), eating disorders (n=4, 12%), MDD (n=9, 27%), suicide ideations (n=5, 15%), attention deficit disorder (n=9, 24%), and other mental health conditions (n=1, 3%). Among the 33 patients with documented mental health conditions, 19 (58%) patients were taking medications related to mental health (Table I).

Conclusions
Our results estimate a 29% prevalence of mental health conditions in youth with IBD at MCH. A lack of mental health resources and screening protocols within this setting could result in an underrepresentation of adolescents with IBD and mental health comorbidities. Future studies will focus on incorporating screening methods for mental health conditions within pediatric healthcare settings to determine current barriers and accessibility to mental health supports.

Table I. Medications in patients (n=33) with documented mental health condition

Note
Medications were prevalent in patients with ampersand:003E1 mental health diagnosis, thus frequency is lower than # of documented mental health diagnoses.
*Other mental health conditions: borderline personality disorder and bipolar disorder with depression.

Funding Agencies
None
A88 ADVERSE EVENTS ASSOCIATED WITH ENDOSCOPIC RETROGRADE CHOLANGIOPANCREATOGRAPHY: A SYSTEMATIC REVIEW AND META-ANALYSIS
Authors: Guo H , Bishay K , Meng Z , Ruan Y , Brenner D , Forbes N 
Published: February 2024

Abstract

Background
Endoscopic retrograde cholangiopancreatography (ERCP) is a widely utilized procedure for diagnosing and managing various biliary and pancreatic disorders. Despite its established effectiveness, ERCP is associated with a total adverse event (AE) rate exceeding 10%. However, existing literature lacks a comprehensive synthesis of incidence rates pertaining to specific or overall AEs following ERCP procedures.

Aims
We performed separate systematic reviews and meta-analyses of (1) data from randomized controlled trials (RCTs) and (2) data from observational studies to evaluate the incidence of AEs following ERCPs in adult patients.

Methods
Two separate systematic literature searches were conducted to identify ERCP AE rates in RCTs and observational studies published between 2000 and 2021, inclusive. Abstracts underwent independent assessment to identify studies for full-text review and subsequent data extraction. DerSimonian and Laird random effects meta-analyses were applied to determine pooled incidence rates of individual post-ERCP AEs, accompanied by 95% confidence intervals (CIs). The Newcastle-Ottawa Scale (NOS) and Risk of Bias 2 (ROB2) tool were used for quality assessment of observational studies and RCTs respectively.

Results
Our analysis incorporated 242 RCTs and 143 observational studies. Among RCTs, the pooled incidences of post-ERCP pancreatitis (PEP) in patients with native and non-native papillae were 6.9% (CI 6.2% to 7.6%) and 6.1% (CI 5.3% to 7.1%), respectively. In observational studies, the pooled PEP incidences were 5.0% (CI 4.0% to 6.1%) for patients with native papillae and 4.2% (CI 3.6% to 4.8%) for patients with non-native papillae. The incidences of bleeding for patients with native papillae were 1.6% (CI 1.3% to 2.0%) and 2.2% (CI 1.2% to 3.9%) in RCTs and observational studies, respectively. The incidences of perforation for patients with native papillae were 0.3% (CI 0.2% to 0.4%) in RCTs and 0.5% (CI 0.3% to 0.7%) in observational studies. The incidence of cholangitis was 1.4% (CI 1.1% to 1.9%) in RCTs and 1.1% (CI 0.7% to 1.7%) in observational studies.

Conclusions
This meta-analysis offers comprehensive insights into the incidence of ERCP-associated AEs from 2000 to 2021, both in idealized study settings where procedures are performed by experts, and in ‘real world’ settings. More precise estimates of ERCP-related AEs can help facilitate patient consent, manage appropriate patient expectations, and enhance peri-procedural care.

Funding Agencies
None