Paul P. Bertrand

Helicobacter pylori infection causes inflammation in the gastric mucosa, and this has been reported to disrupt the gastric microbiota. Serotonin (5-HT) is a key neurotransmitter in the gut–brain axis and plays key roles in intestinal homeostasis and immune function. We investigated gastric serotonin release in H. pylori-infected mice and observed increased release in vaccinated, challenged mice compared to sham vaccinated controls. We investigated the effects of 5-HT on epithelial responses in an in vitro human gastric cancer cell line model (AGS), as well as inflammatory responses and the gastric microbiota in a C57BL/6 mouse model of H. pylori infection. HTR1A was upregulated in the stomachs of mice chronically infected with H. pylori SS1 (3 weeks) compared to uninfected controls, whereas HTR2B was upregulated only in acutely infected mice (3 days), consistent with a role for 5-HT signalling in the development of gastritis. Exposure to 5-HT did not affect NF-κB activation in H. pylori-exposed AGS cells but did inhibit extracellular signal-regulated kinase 1 (ERK1) translocation. Analysis of the gastric microbiota revealed that while vaccination did not significantly affect the diversity of the microbiota, vaccinated animals had increased abundance of Lactobacilli. Our results suggest that local inflammation caused by H. pylori is responsible for increased 5-HT release.

Nausea and vomiting are common gastrointestinal side effects of oxaliplatin chemotherapy used for the treatment of colorectal cancer. However, the mechanism underlying oxaliplatin-induced nausea and vomiting is unknown. The stomach is involved in the emetic reflex but no study investigated the effects of oxaliplatin treatment on the stomach. In this study, the in vivo effects of oxaliplatin treatment on eating behaviour, stomach content, intrinsic gastric neuronal population, extrinsic innervation to the stomach, levels of mucosal serotonin (5-hydroxytryptamine, 5-HT), and parasympathetic vagal efferent nerve activity were analysed. Chronic systemic oxaliplatin treatment in mice resulted in pica, indicated by increased kaolin consumption and a reduction in body weight. Oxaliplatin treatment significantly increased the stomach weight and content. The total number of myenteric and nitric oxide synthase-immunoreactive neurons as well as the density of sympathetic, parasympathetic, and sensory fibres in the stomach were decreased significantly with oxaliplatin treatment. Oxaliplatin treatment significantly increased the levels in mucosal 5-HT and the number of enterochromaffin-like cells. Chronic oxaliplatin treatment also caused a significant increase in the vagal efferent nerve activity. The findings of this study indicate that oxaliplatin exposure has adverse effects on multiple components of gastric innervation, which could be responsible for pica and gastric dysmotility.

For decades, traditional in vitro and in vivo models used for the study of Helicobacter pylori infection have relied heavily on the use of gastric cancer cell lines and rodents. Major challenges faced by these methods have been the inability to study cancer initiation in already cancerous cell lines, and the difficulty in translating results obtained in animal models due to genetic differences. These challenges have prevented a thorough understanding of the pathogenesis of disease and slowed the development of cancer therapies and a suitable vaccine against the pathogen. In recent years, the development of gastric organoids has provided great advantages over the traditional in vivo and in vitro models due to their similarities to the human stomach in vivo, their ease of use, and the capacity for long‐term culture. This review discusses the advantages and limitations of existing in vivo and in vitro models of H. pylori infection, and how gastric organoids have been applied to study H. pylori pathogenesis, with a focus on how the pathogen interacts with the gastric epithelium, inflammatory processes, epithelial repair, and cancer initiation. The potential applications of organoids to address more complex questions on the role of hormones, vaccine‐induced immunity are also discussed.

Gastric cancer represents a significant disease burden worldwide. The factors that initiate cancer are not well understood. Chronic inflammation such as that triggered by H. pylori infection is the most significant cause of gastric cancer. In recent years, organoid cultures developed from human and animal adult stem cells have facilitated great advances in our understanding of gastric homeostasis. Organoid models are now being exploited to investigate the role of host genetics and bacterial factors on proliferation and DNA damage in gastric stem cells. The impact of a chronic inflammatory state on gastric stem cells and the stroma has been less well addressed. This review discusses what we have learned from the use of organoid models to investigate cancer initiation, and highlights questions on the contribution of the microbiota, chronic inflammatory milieu, and stromal cells that can now be addressed by more complex coculture models.

Introduction: The pannexin-1 (Panx1) channels are found in many cell types, and ATP released from these channels can act on nearby cells activating purinergic P2X7 receptors (P2X7R) which lead to inflammation. Although Panx1 and P2X7R are implicated in the process of inflammation and cell death, few studies have looked at the role they play in inflammatory bowel disease in human. Hence, the aim of the present study was to investigate the function of Panx1 and P2X7R in an ex vivo colitis model developed from human colonic mucosal explants. Materials and Methods: Healthy human colonic mucosal strips (4 × 10 mm) were incubated in carbogenated culture medium at 37°C for 16 h. Proinflammatory cytokines TNFα and IL-1β (each 10 ng/mL) were used to induce colitis in mucosal strips, and the effects of Panx1 and P2X7R on cytokines-induced tissue damage were determined in the presence of the Panx1 channel blocker ¹⁰Panx1 (100 μM) and P2X7R antagonist A438079 (100 μM). The effects of ¹⁰Panx1 and A438079 on cytokines-enhanced epithelial permeability were also studied using Caco-2 cells. Results: Histological staining showed that the mucosal strips had severe structural damage in the cytokines-only group but not in the incubation-control group (P < 0.01). Compared to the cytokines-only group, crypt damage was significantly decreased in groups receiving cytokines with inhibitors (¹⁰Panx1, A438079, or ¹⁰Panx1 + A438079, P < 0.05). The immunoreactive signals of tight junction protein zonula occludens-1 (ZO-1) were abundant in all control tissues but were significantly disrupted and lost in the cytokines-only group (P < 0.01). The diminished ZO-1 immunoreactivity induced by cytokines was prevented in the presence of ¹⁰Panx1 (P = 0.04). Likewise, ¹⁰Panx1 significantly attenuated the cytokines-evoked increase in paracellular permeability of Caco-2 cells. Although the inhibition of P2X7R activity by A438079 diminished cytokines-induced crypt damage, its effect on the maintenance of ZO-1 immunoreactivity and Caco-2 epithelial cell integrity was less evident. Conclusion: The blockade of Panx1 and P2X7R reduced the inflammatory cytokines-induced crypt damage, loss of tight junctions and increase in cell permeability. Thus, Panx1 and P2X7R may have roles in causing mucosal damage, a common clinical feature of inflammatory bowel disease.

Serotonin (5-hydroxytryptamine, 5-HT) has been linked with several inflammation-associated intestinal diseases, including ulcerative colitis (UC). The largest pool of 5-HT in the body is in enterochromaffin (EC) cells located throughout the intestinal tract. EC cells are mechanosensitive and detect noxious stimuli, inducing secretion of 5-HT, which plays an important role in enteric reflexes and immunomodulation. In this study, we evaluated intestinal 5-HT levels in the Winnie mouse model of spontaneous chronic colitis, which closely replicates UC. Real-time electrochemical recordings of 5-HT oxidation currents were obtained from ex vivo preparations of jejunum, ileum, proximal, and distal colon from Winnie (5–25 weeks old) and age matched C57BL/6 mice. EC cells were examined by immunohistochemistry, and the gene expression of tryptophan hydroxylase 1 (5-HT synthesis) and the serotonin reuptake transporter (SERT) were determined by quantitative Real-Time Polymerase Chain Reaction (RT-qPCR). Compression-evoked and basal 5-HT concentrations were elevated in the distal and proximal colon of Winnie mice. EC cell hyperplasia and downregulation of SERT on the transcriptional level were identified as mechanisms underlying increased levels of 5-HT. Increase in mucosal 5-HT release was observed at the onset of disease at 7–14 weeks, confirmed by disease activity scores. Furthermore, increases in 5-HT levels and progression of disease activity correlated linearly with age, but not sex. Our findings in the Winnie mouse model of spontaneous chronic colitis demonstrate for the first time that the onset and progression of chronic UC-like intestinal inflammation is associated with increased 5-HT levels in the colonic mucosa.

Objectives: Dysphagia is common in total laryngectomees, with some symptoms suggesting esophageal dysmotility. Tracheoesophageal (TE) phonation requires effective esophagopharyngeal air passage. Hence, esophageal dysmotility may affect deglutition or TE phonation. This study aimed to determine (1) the characteristics of esophageal dysmotility in laryngectomees, (2) whether clinical history is sensitive in detecting esophageal dysmotility, and (3) the relationship between esophageal dysmotility and TE prosthesis dysfunction.Study Design: Multidisciplinary cross‐sectional study.Setting: Tertiary academic hospital.Subjects and Methods: For 31 participants undergone total laryngectomy 1 to 12 years prior, clinical histories were taken by a gastroenterologist and a speech pathologist experienced in managing dysphagia. Esophageal high‐resolution manometry was performed and analyzed using Chicago Classification v3.0.Results: Interpretable manometric studies were obtained in 23 (1 normal manometry). Esophageal dysmotility patterns included achalasia, esophagogastric junction outflow obstruction, diffuse esophageal spasm, and other major (30%) and minor (50%) peristaltic disorders. The sensitivity of predicting any esophageal dysmotility was 28%, but it is noteworthy that patients with achalasia and diffuse esophageal spasm (DES) were predicted. Two of 4 participants with TE puncture leakage had poor esophageal clearance. Of 20 TE speakers, 12 had voice problems, no correlation between poor voice, and any dysmotility pattern.Conclusions: Peristaltic and lower esophageal sphincter dysfunction are common in laryngectomees. Clinical history, while not predictive of minor motor abnormalities, predicted correctly cases with treatable spastic motor disorders. Dysmotility was not associated with poor phonation, although TE puncture leakage might be linked to poor esophageal clearance. Esophageal dysmotility should be considered in the laryngectomees with persisting dysphagia or leaking TE puncture.

Altered gastrointestinal (GI) function contributes to the debilitating symptoms of inflammatory bowel diseases (IBD). Nerve circuits contained within the gut wall and outside of the gut play important roles in modulating motility, mucosal fluid transport, and blood flow. The structure and function of these neuronal populations change during IBD. Superimposed on this plasticity is a diminished responsiveness of effector cells — smooth muscle cells, enterocytes, and vascular endothelial cells — to neurotransmitters. The net result is a breakdown in the precisely orchestrated coordination of motility, fluid secretion, and GI blood flow required for health. In this review, we consider how inflammation-induced changes to the effector innervation of these tissues, and changes to the tissues themselves, contribute to defective GI function in models of IBD. We also explore the evidence that reversing neuronal plasticity is sufficient to normalize function during IBD.

Objective: Postlaryngectomy, pharyngeal weakness, and pharyngoesophageal junction (PEJ) restriction are the candidate mechanisms of dysphagia. The aims were, in laryngectomees, whether (1) hypopharyngeal propulsion is reduced and/or PEJ resistance is increased, (2) dilatation improves dysphagia, and (3) whether symptomatic improvement correlates with reduced PEJ resistance.Design: Multidisciplinary cross‐sectional study.Setting: Tertiary academic hospital.Subjects and Methods: Swallow biomechanics were assessed in 30 laryngectomees. Patients were stratified into severe dysphagia (Sydney Swallow Questionnaire >500) and mild/nil dysphagia (Sydney Swallow Questionnaire ≤500). Average hypopharyngeal peak (contractile) pressure (hPP) and hypopharyngeal intrabolus pressure (hIBP) were measured from high‐resolution manometry with concurrent videofluoroscopy based on barium swallows (2.5 and 10 mL). In consecutive 5 patients, measurements were repeated after dilatation.Results: Dysphagia was reported by 87%, and 57% had severe and 43% had mild/nil dysphagia. hIBP increased with larger bolus volumes (P <. 0001), while hPP stayed stable and PEJ diameter plateaued at 9 mm. Laryngectomees had lower hPP (110 ± 14 vs 170 ± 15 mm Hg; P =. 0162) and higher hIBP (29 ± 5 vs 6 ± 5 mm Hg; P =. 156) than controls. There were no differences in hPP between patient groups. However, hIBP was higher in severe than in mild/nil dysphagia (41 ± 10 vs 13 ± 3 mm Hg; P =. 02). Predilation hIBP (R² = 0.97) and its decrement postdilatation (R² = 0.98) well predicted symptomatic improvement.Conclusions: PEJ resistance correlates better with dysphagia severity than peak pharyngeal pressure and is more sensitive to bolus sizes than PEJ diameter. Both baseline PEJ resistance and its decrement following dilatation are strong predictors of treatment outcome. PEJ resistance is vital to detect, as it is reversible and can predict the response to dilatation regimens.