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Gut Dec 2022Cigarette smoking is a major risk factor for colorectal cancer (CRC). We aimed to investigate whether cigarette smoke promotes CRC by altering the gut microbiota and...
OBJECTIVE
Cigarette smoking is a major risk factor for colorectal cancer (CRC). We aimed to investigate whether cigarette smoke promotes CRC by altering the gut microbiota and related metabolites.
DESIGN
Azoxymethane-treated C57BL/6 mice were exposed to cigarette smoke or clean air 2 hours per day for 28 weeks. Shotgun metagenomic sequencing and liquid chromatography mass spectrometry were parallelly performed on mice stools to investigate alterations in microbiota and metabolites. Germ-free mice were transplanted with stools from smoke-exposed and smoke-free control mice.
RESULTS
Mice exposed to cigarette smoke had significantly increased tumour incidence and cellular proliferation compared with smoke-free control mice. Gut microbial dysbiosis was observed in smoke-exposed mice with significant differential abundance of bacterial species including the enrichment of and depletion of and spp. Metabolomic analysis showed increased bile acid metabolites, especially taurodeoxycholic acid (TDCA) in the colon of smoke-exposed mice. We found that had the most positive correlation with TDCA in smoke-exposed mice. Moreover, smoke-exposed mice manifested enhanced oncogenic MAPK/ERK (mitogen-activated protein kinase/extracellular signal‑regulated protein kinase 1/2) signalling (a downstream target of TDCA) and impaired gut barrier function. Furthermore, germ-free mice transplanted with stools from smoke-exposed mice (GF-AOMS) had increased colonocyte proliferation. Similarly, GF-AOMS showed increased abundances of gut and TDCA, activated MAPK/ERK pathway and impaired gut barrier in colonic epithelium.
CONCLUSION
The gut microbiota dysbiosis induced by cigarette smoke plays a protumourigenic role in CRC. The smoke-induced gut microbiota dysbiosis altered gut metabolites and impaired gut barrier function, which could activate oncogenic MAPK/ERK signalling in colonic epithelium.
Topics: Animals; Mice; Gastrointestinal Microbiome; Dysbiosis; Cigarette Smoking; Mice, Inbred C57BL; Carcinogenesis; Colorectal Neoplasms
PubMed: 35387878
DOI: 10.1136/gutjnl-2021-325021 -
Gut Apr 2023Functional gastrointestinal disorders-recently renamed into disorders of gut-brain interaction-such as irritable bowel syndrome and functional dyspepsia are highly... (Review)
Review
Functional gastrointestinal disorders-recently renamed into disorders of gut-brain interaction-such as irritable bowel syndrome and functional dyspepsia are highly prevalent conditions with bothersome abdominal symptoms in the absence of structural abnormalities. While traditionally considered as motility disorders or even psychosomatic conditions, our understanding of the pathophysiology has evolved significantly over the last two decades. Initial observations of subtle mucosal infiltration with immune cells, especially mast cells and eosinophils, are since recently being backed up by mechanistic evidence demonstrating increased release of nociceptive mediators by immune cells and the intestinal epithelium. These mediators can activate sensitised neurons leading to visceral hypersensitivity with bothersome symptoms. The interaction between immune activation and an impaired barrier function of the gut is most likely a bidirectional one with alterations in the microbiota, psychological stress and food components as upstream players in the pathophysiology. Only few immune-targeting treatments are currently available, but an improved understanding through a multidisciplinary scientific approach will hopefully identify novel, more precise treatment targets with ultimately better outcomes.
Topics: Humans; Neuroimmunomodulation; Gastrointestinal Diseases; Irritable Bowel Syndrome; Brain; Dyspepsia
PubMed: 36657961
DOI: 10.1136/gutjnl-2020-320633 -
Gut Apr 2023Haematogenous dissemination is a prevalent route of colorectal cancer (CRC) metastasis. However, as the gatekeeper of vessels, the role of tumour pericytes (TPCs) in...
OBJECTIVE
Haematogenous dissemination is a prevalent route of colorectal cancer (CRC) metastasis. However, as the gatekeeper of vessels, the role of tumour pericytes (TPCs) in haematogenous metastasis remains largely unknown. Here, we aimed to investigate the heterogeneity of TPCs and their effects on CRC metastasis.
DESIGN
TPCs were isolated from patients with CRC with or without liver metastases and analysed by single-cell RNA sequencing (scRNA-seq). Clinical CRC specimens were collected to analyse the association between the molecular profiling of TPCs and CRC metastasis. RNA-sequencing, chromatin immunoprecipitation-sequencing and bisulfite-sequencing were performed to investigate the TCF21-regulated genes and mechanisms underlying integrin α5 on DNA hypermethylation. Pericyte-conditional -knockout mice were constructed to investigate the effects of TCF21 in TPCs on CRC metastasis. Masson staining, atomic force microscopy, second-harmonic generation and two-photon fluorescence microscopy were employed to observe perivascular extracellular matrix (ECM) remodelling.
RESULTS
Thirteen TPC subpopulations were identified by scRNA-seq. A novel subset of TCF21 TPCs, termed 'matrix-pericytes', was associated with liver metastasis in patients with CRC. TCF21 in TPCs increased perivascular ECM stiffness, collagen rearrangement and basement membrane degradation, establishing a perivascular metastatic microenvironment to instigate colorectal cancer liver metastasis (CRCLM). depletion in TPCs mitigated perivascular ECM remodelling and CRCLM, whereas the coinjection of TCF21 TPCs and CRC cells markedly promoted CRCLM. Mechanistically, loss of integrin α5 inhibited the FAK/PI3K/AKT/DNMT1 axis to impair DNA hypermethylation in TCF21 TPCs.
CONCLUSION
This study uncovers a previously unidentified role of TPCs in haematogenous metastasis and provides a potential diagnostic marker and therapeutic target for CRC metastasis.
Topics: Animals; Mice; Cell Line, Tumor; Colorectal Neoplasms; DNA; Gene Expression Regulation, Neoplastic; Integrin alpha5; Liver Neoplasms; Neoplasm Metastasis; Pericytes; Phosphatidylinositol 3-Kinases; Tumor Microenvironment
PubMed: 36805487
DOI: 10.1136/gutjnl-2022-327913 -
Gut Sep 2000Evaluation of histological activity in ulcerative colitis needs to be reproducible but has rarely been tested. This could be useful both clinically and in clinical...
BACKGROUND
Evaluation of histological activity in ulcerative colitis needs to be reproducible but has rarely been tested. This could be useful both clinically and in clinical trials.
AIM
To develop reproducible criteria which are valid in the assessment of acute inflammation (activity) and chronicity, and to evaluate these features in an interobserver variability study.
METHODS
A six grade classification system for inflammation was developed which could also be fine tuned within each grade. The grades were: 0, structural change only; 1, chronic inflammation; 2, lamina propria neutrophils; 3, neutrophils in epithelium; 4, crypt destruction; and 5, erosions or ulcers. Ninety nine haematoxylin-eosin sections from endoscopically inflamed and non-inflamed mucosa from patients with distal ulcerative colitis were assessed in two separate readings by three pathologists independently and without knowledge of the clinical status. Interobserver agreement was compared pairwise using kappa statistics.
RESULTS
Initially, kappa values between the observers were 0.20, 0.42, and 0.26, which are too low to be of value. Following development of a semiquantitative pictorial scale for each criterion, kappa values improved to 0.62, 0.70, and 0.59. For activity defined by neutrophils between epithelial cells, kappa values were 0.903, 1.000, and 0.907. Complete agreement was reached in 64% of samples of endoscopically normal and in 66% of endoscopically inflamed tissue. Neutrophils in epithelium correlated with the presence of crypt destruction and ulceration.
CONCLUSION
A histological activity system was developed for ulcerative colitis that showed good reproducibility and modest agreement with the endoscopic grading system which it complemented. It has potential value both clinically and in clinical trials.
Topics: Biopsy; Colitis, Ulcerative; Humans; Observer Variation; Reproducibility of Results; Severity of Illness Index
PubMed: 10940279
DOI: 10.1136/gut.47.3.404 -
Gut Feb 2023Increased apoptotic shedding has been linked to intestinal barrier dysfunction and development of inflammatory bowel diseases (IBD). In contrast, physiological cell...
OBJECTIVE
Increased apoptotic shedding has been linked to intestinal barrier dysfunction and development of inflammatory bowel diseases (IBD). In contrast, physiological cell shedding allows the renewal of the epithelial monolayer without compromising the barrier function. Here, we investigated the role of live cell extrusion in epithelial barrier alterations in IBD.
DESIGN
Taking advantage of conditional GGTase and RAC1 knockout mice in intestinal epithelial cells ( and mice), intravital microscopy, immunostaining, mechanobiology, organoid techniques and RNA sequencing, we analysed cell shedding alterations within the intestinal epithelium. Moreover, we examined human gut tissue and intestinal organoids from patients with IBD for cell shedding alterations and RAC1 function.
RESULTS
Epithelial deletion led to cytoskeleton rearrangement and tight junction redistribution, causing cell overcrowding due to arresting of cell shedding that finally resulted in epithelial leakage and spontaneous mucosal inflammation in the small and to a lesser extent in the large intestine. Both in vivo and in vitro studies (knockout mice, organoids) identified RAC1 as a GGTase target critically involved in prenylation-dependent cytoskeleton dynamics, cell mechanics and epithelial cell shedding. Moreover, inflamed areas of gut tissue from patients with IBD exhibited funnel-like structures, signs of arrested cell shedding and impaired RAC1 function. RAC1 inhibition in human intestinal organoids caused actin alterations compatible with arresting of cell shedding.
CONCLUSION
Impaired epithelial RAC1 function causes cell overcrowding and epithelial leakage thus inducing chronic intestinal inflammation. Epithelial RAC1 emerges as key regulator of cytoskeletal dynamics, cell mechanics and intestinal cell shedding. Modulation of RAC1 might be exploited for restoration of epithelial integrity in the gut of patients with IBD.
Topics: Animals; Humans; Mice; Cytoskeleton; Epithelial Cells; Inflammation; Inflammatory Bowel Diseases; Intestinal Mucosa; Mice, Knockout; rac1 GTP-Binding Protein
PubMed: 35241625
DOI: 10.1136/gutjnl-2021-325520 -
Gut Jul 2022Coeliac disease (CD) is a frequent immune enteropathy induced by gluten in genetically predisposed individuals. Its pathogenesis has been extensively studied and CD has... (Review)
Review
Coeliac disease (CD) is a frequent immune enteropathy induced by gluten in genetically predisposed individuals. Its pathogenesis has been extensively studied and CD has emerged as a model disease to decipher how the interplay between environmental and genetic factors can predispose to autoimmunity and promote lymphomagenesis. The keystone event is the activation of a gluten-specific immune response that is driven by molecular interactions between gluten, the indispensable environmental factor, HLA-DQ2/8, the main predisposing genetic factor and transglutaminase 2, the CD-specific autoantigen. The antigluten response is however not sufficient to induce epithelial damage which requires the activation of cytotoxic CD8 intraepithelial lymphocytes (IEL). In a plausible scenario, cooperation between cytokines released by gluten-specific CD4 T cells and interleukin-15 produced in excess in the coeliac gut, licenses the autoimmune-like attack of the gut epithelium, likely via sustained activation of the Janus kinase-signal transducer and activator of transcription (JAK/STAT) pathway in IEL. Demonstration that lymphomas complicating CD arise from IEL that have acquired gain-of-function or mutations stresses the key role of this pathway and explains how gluten-driven chronic inflammation may promote this rare but most severe complication. If our understanding of CD pathogenesis has considerably progressed, several questions and challenges remain. One unsolved question concerns the considerable variability in disease penetrance, severity and presentation, pointing to the role of additional genetic and environmental factors that remain however uneasy to untangle and hierarchize. A current challenge is to transfer the considerable mechanistic insight gained into CD pathogenesis into benefits for the patients, notably to alleviate the gluten-free diet, a burden for many patients.
PubMed: 35879049
DOI: 10.1136/gutjnl-2021-326257 -
Gut Sep 1999Current concepts and basic principles of neurogastroenterology in relation to functional gastrointestinal disorders are reviewed. Neurogastroenterology is emphasized as... (Review)
Review
Current concepts and basic principles of neurogastroenterology in relation to functional gastrointestinal disorders are reviewed. Neurogastroenterology is emphasized as a new and advancing subspecialty of clinical gastroenterology and digestive science. As such, it embraces the investigative sciences dealing with functions, malfunctions, and malformations in the brain and spinal cord, and the sympathetic, parasympathetic and enteric divisions of the autonomic innervation of the digestive tract. Somatomotor systems are included insofar as pharyngeal phases of swallowing and pelvic floor involvement in defecation, continence, and pelvic pain are concerned. Inclusion of basic physiology of smooth muscle, mucosal epithelium, and the enteric immune system in the neurogastroenterologic domain relates to requirements for compatibility with neural control mechanisms. Psychologic and psychiatric relations to functional gastrointestinal disorders are included because they are significant components of neurogastroenterology, especially in relation to projections of discomfort and pain to the digestive tract.
Topics: Colonic Diseases, Functional; Digestive System; Digestive System Physiological Phenomena; Enteric Nervous System; Humans; Mast Cells; Motor Neurons
PubMed: 10457039
DOI: 10.1136/gut.45.2008.ii6 -
Gut Mar 2002The glucagon-like peptides GLP-1 and GLP-2 are synthesised and then released from enteroendocrine cells in the small and large intestine. GLP-1 promotes efficient... (Review)
Review
The glucagon-like peptides GLP-1 and GLP-2 are synthesised and then released from enteroendocrine cells in the small and large intestine. GLP-1 promotes efficient nutrient assimilation while GLP-2 regulates energy absorption via effects on nutrient intake, gastric acid secretion and gastric emptying, nutrient absorption, and mucosal permeability. Preliminary human studies indicate that GLP-2 may enhance energy absorption and reduce fluid loss in subjects with short bowel syndrome suggesting that GLP-2 functions as a key regulator of mucosal integrity, permeability, and nutrient absorption. Hence GLP-2 may be therapeutically useful in diseases characterised by injury or dysfunction of the gastrointestinal epithelium.
Topics: Adaptation, Physiological; Animals; Glucagon; Glucagon-Like Peptide 1; Glucagon-Like Peptide 2; Humans; Intestinal Diseases; Intestines; Mice; Peptide Fragments; Peptides; Protein Precursors; Rats; Short Bowel Syndrome
PubMed: 11839727
DOI: 10.1136/gut.50.3.428 -
Gut May 2002Bacterial pathogens have evolved two major strategies to colonise the intestinal epithelium. Adherent microorganisms bind to the apical pole of the intestinal... (Review)
Review
Bacterial pathogens have evolved two major strategies to colonise the intestinal epithelium. Adherent microorganisms bind to the apical pole of the intestinal epithelium, whereas invasive microorganisms disrupt and invade the epithelium. Recognition of the genetic bases of bacterial pathogenicity and analysis of the molecular cross talks established between pathogens and their mammalian target cells have illuminated this diversity of interactions. We have compared the strategies of enteroinvasive pathogens, with emphasis on bacterial species such as Shigella, Yersinia, and Salmonella, that represent paradigms of interaction. Cross talks leading to alteration of the epithelial cell actin cytoskeleton appear as a recurrent theme during entry and dissemination into epithelial cells. Other cross talks alter the trafficking of cellular vesicles and induce changes in the intracellular compartment in which they reside, thus creating niches favourable to bacterial survival and growth. Finally, a variety of strategies also exist to deal with other components of the epithelial barrier, such as macrophages. Pro-phagocytic, anti-phagocytic, and pro-apoptotic processes appear to be of particular importance.
Topics: Actins; Animals; Bacterial Adhesion; Bacterial Infections; Bacterial Translocation; Cell Membrane; Cytoskeleton; Dendritic Cells; Epithelium; Intestinal Diseases; Intestinal Mucosa; Macrophages; Salmonella; Shigella; Yersinia
PubMed: 11953325
DOI: 10.1136/gut.50.suppl_3.iii2 -
Gut Jun 1995The colorectal biopsy specimens from 30 patients with chronic watery diarrhoea but normal endoscopic and radiographic findings were studied by light microscopy,...
The colorectal biopsy specimens from 30 patients with chronic watery diarrhoea but normal endoscopic and radiographic findings were studied by light microscopy, morphometry, immunohistochemistry, and two patients with electron microscopy. The histological changes in the colorectum were originally diagnosed in six patients as lymphocytic colitis and in 24 patients as collagenous colitis. The analysis of the specimens for this study could delineate three distinct groups of microscopic colitis: lymphocytic colitis (six patients), collagenous colitis without lymphocytic attack on the surface epithelium (seven patients), and a mixed form presenting with both thickening of the collagen plate and increased number of intraepithelial lymphocytes (17 patients). No transformation was seen from one type to another during follow up of six patients for four to seven years. Increased numbers of active pericryptal myofibroblasts were found with the electron microscope in one patient with mixed microscopic colitis showing also myofibroblasts entrapped within the collagen layer. Hitherto undescribed flat mucosa of the ileum was found in one patient with lymphocytic colitis and both flat mucosa and thickening of the collagen plate in the ileum were seen in one patient with the mixed form of the disease. In another patient with mixed microscopic colitis, normalisation of the colorectal morphology occurred after temporary loop ileostomy, followed by the reappearance of both diarrhoea, inflammation, and thickening of the collagen plate after the ileostomy was reversed. No association was found between non-steroid anti-inflammatory drug (NSAID) consumption and collagenous or mixed microscopic colitis. The primary cause of microscopic colitis is probably an immunological reaction to luminal antigen/s, perhaps of ileal origin. The engagement of the pericryptal myofibroblasts in the disease process might result in the development of the various forms of microscopic colitis. An inverse relation between intraepithelial lymphocyte count and collagen thickness may indicate that microscopic colitis is a spectral disease.
Topics: Adult; Biopsy; Colitis; Collagen; Colon; Epithelium; Female; Follow-Up Studies; Humans; Intestinal Mucosa; Lymphocyte Count; Male; Rectum
PubMed: 7615277
DOI: 10.1136/gut.36.6.880