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Wetzel S, Müller A, Kohnert E, Mehrbarzin N, Huber R, Häcker G, Kreutz C, Lederer AK, Badr MT. Longitudinal dynamics of gut bacteriome and mycobiome interactions pre- and post-visceral surgery in Crohn's disease. Front Cell Infect Microbiol 2024; 13:1275405. [PMID: 38287975 PMCID: PMC10822897 DOI: 10.3389/fcimb.2023.1275405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 12/12/2023] [Indexed: 01/31/2024] Open
Abstract
Introduction Alterations of the gut microbiome are involved in the pathogenesis of Crohn's disease (CD). The role of fungi in this context is unclear. This study aimed to determine postoperative changes in the bacterial and fungal gut communities of CD patients undergoing intestinal resection, and to evaluate interactions between the bacteriome and mycobiome and their impact on the patients' outcome. Methods We report a subgroup analysis of a prospective cohort study, focusing on 10 CD patients whose fecal samples were collected for bacterial 16S rRNA and fungal ITS2 genes next-generation sequencing the day before surgery and on the 5th or 6th postoperative day. Results No significant differences in bacterial and fungal diversity were observed between preoperative and postoperative stool samples. By in-depth analysis, significant postoperative abundance changes of bacteria and fungi and 17 interkingdom correlations were detected. Network analysis identified 13 microbial clusters in the perioperative gut communities, revealing symbiotic and competitive interactions. Relevant factors were gender, age, BMI, lifestyle habits (smoking, alcohol consumption) and surgical technique. Postoperative abundance changes and identified clusters were associated with clinical outcomes (length of hospital stay, complications) and levels of inflammatory markers. Conclusions Our findings highlight the importance of dissecting the interactions of gut bacterial and fungal communities in CD patients and their potential influence on postoperative and disease outcomes.
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Affiliation(s)
- Simon Wetzel
- Institute of Medical Microbiology and Hygiene, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Alexander Müller
- Center for Complementary Medicine, Department of Medicine II, Medical Center—University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Eva Kohnert
- Institute of Medical Biometry and Statistics, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Negin Mehrbarzin
- Institute of Medical Microbiology and Hygiene, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Roman Huber
- Center for Complementary Medicine, Department of Medicine II, Medical Center—University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Georg Häcker
- Institute of Medical Microbiology and Hygiene, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Centre for Biological Signaling Studies (BIOSS), University of Freiburg, Freiburg, Germany
| | - Clemens Kreutz
- Institute of Medical Biometry and Statistics, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Ann-Kathrin Lederer
- Center for Complementary Medicine, Department of Medicine II, Medical Center—University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Department of General, Visceral and Transplant Surgery, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Mohamed Tarek Badr
- Institute of Medical Microbiology and Hygiene, Medical Center–University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Aufdecken gemeinsamer Prinzipien immunvermittelter Erkrankungen: von der Grundlagenwissenschaft zu neuen Therapien (IMM-PACT)-Program, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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Jarmakiewicz-Czaja S, Zielińska M, Sokal A, Filip R. Genetic and Epigenetic Etiology of Inflammatory Bowel Disease: An Update. Genes (Basel) 2022; 13. [PMID: 36553655 DOI: 10.3390/genes13122388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/06/2022] [Accepted: 12/09/2022] [Indexed: 12/23/2022] Open
Abstract
Inflammatory bowel disease (IBD) is a chronic disease with periods of exacerbation and remission of the disease. The etiology of IBD is not fully understood. Many studies point to the presence of genetic, immunological, environmental, and microbiological factors and the interactions between them in the occurrence of IBD. The review looks at genetic factors in the context of both IBD predisposition and pharmacogenetics.
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Connelly TM, Lincango E, Holubar SD. Crohn's of the Pouch: Now What? Clin Colon Rectal Surg 2022; 35:475-486. [PMID: 36591396 PMCID: PMC9797285 DOI: 10.1055/s-0042-1758139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Total proctocolectomy and ileal pouch anal anastomosis (IPAA) is the gold standard surgical treatment for the majority (∼90%) of ulcerative colitis (UC) patients. In cases of carefully selected Crohn's colitis patients without small bowel or perianal involvement an "intentional IPAA" may be a viable option for disease resection and restoration of intestinal continuity. More commonly, Crohn's is incidentally found either in the resection specimen or, more commonly, when inflammatory complications subsequently arise after pouch construction for UC or indeterminate colitis. These incidental Crohn's pouches may be diagnosed early or late period post-IPAA. Crohn's may manifest within the pouch, in the proximal small bowel, and/or distally in the rectal cuff or anus. Like intestinal Crohn's, Crohn's disease of the pouch may be of an inflammatory, fibrostenosing, or fistulizing phenotype. Treatment depends on the phenotype and includes medical treatment, most commonly in the form of tumor necrosis factor inhibitor medications; however, the newer small molecules offer a potential treatment for these patients. Surgery first entails treating the sequelae of Crohn's and is typically staged. In up to 60% of Crohn's pouches, particularly in fistulizing disease and/or recalcitrant perianal disease, the pouch fails and must be defunctioned or excised. In patients with Crohn's pouches in situ long term, outcomes including quality of life are comparable to patients who underwent IPAA for UC.
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Affiliation(s)
- Tara M. Connelly
- Department of Colorectal Surgery, Digestive Disease and Surgery Institute, Cleveland Clinic, Cleveland, Ohio
| | - Eddy Lincango
- Department of Colorectal Surgery, Digestive Disease and Surgery Institute, Cleveland Clinic, Cleveland, Ohio
| | - Stefan D. Holubar
- Department of Colorectal Surgery, Digestive Disease and Surgery Institute, Cleveland Clinic, Cleveland, Ohio
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Kumar A, Al-Hassi HO, Steed H, Phipps O, Brookes MJ. Bile Acids and the Microbiome: Making Sense of This Dynamic Relationship in Their Role and Management in Crohn's Disease. Can J Gastroenterol Hepatol 2022; 2022:8416578. [PMID: 35360442 DOI: 10.1155/2022/8416578] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Accepted: 03/05/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Bile acids help maintain the physiological balance of the gut microbiome and the integrity of the intestinal epithelial barrier. Similarly, intestinal bacteria play a major role in bile acid metabolism as they are involved in crucial biotransformation steps in the enterohepatic circulation pathway. Understanding the relationship between bile acid signalling and the gut microbiome in Crohn's disease can help target new and innovative treatment strategies. AIMS This review summarises the relationship between bile acids and the microbiome in Crohn's disease and discusses potential novel therapeutic options. METHODS We performed a literature review on bile acid signalling, its effect on the gut microbiome, and therapeutic applications in Crohn's disease. RESULTS Current research suggests that there is a strong interplay between the dysregulated microbiota, bile acid metabolism, and the mucosal immune system that can result in a changed immunological function, triggering the inflammatory response in Crohn's disease. Recent studies have demonstrated an association with altering the enterohepatic circulation and activating the farnesoid X receptor signalling pathway with the use of probiotics and faecal microbial transplantation, respectively. Bile acid sequestrants have been shown to have anti-inflammatory, cytoprotective, and anti-apoptotic properties with the potential to alter the intestinal microbial composition, suggesting a possible role in inducing and maintaining Crohn's disease. CONCLUSIONS Active Crohn's disease has been correlated with changes in bacterial concentrations, which may be associated with changes in bile acid modification. Further research should focus on targeting these areas for future therapeutic options.
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Karpinska-Leydier K, Amirthalingam J, Alshowaikh K, Iroshani Jayarathna A, Salibindla DBAMR, Paidi G, Ergin HE. Correlation Between the Gut Microbiome and Immunotherapy Response in Inflammatory Bowel Disease: A Systematic Review of the Literature. Cureus 2021; 13:e16808. [PMID: 34350086 PMCID: PMC8325948 DOI: 10.7759/cureus.16808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 08/01/2021] [Indexed: 11/09/2022] Open
Abstract
Inflammatory bowel disease (IBD) is an autoimmune disease associated with dysbiosis within the gastrointestinal tract. Characteristic taxonomic shifts of microbial populations are observed in disease progression and remission; however, despite similarities, there are many differences among individuals presenting with IBD including IBD subset, clinical course, and response to therapy. Much is still unknown about how these taxonomic shifts interact with immunotherapy and how genetic variants contribute. In this systematic review, we aimed to compile information on the interactions of the gut microbiome with immunotherapy in the course of disease and treatment of IBD patients. This systematic review was conducted as per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and the PubMed database was methodically screened for literature search including keywords and Medical Subject Headings (MeSH) terms for relevant articles. The quality appraisal was completed using the Cochrane Tool, Newcastle-Ottawa checklist, and the Scale for the Assessment of Narrative Review Articles (SANRA) checklist, as appropriate, and 11 relevant articles were included in this systematic review. Our review concludes that although there are characteristic taxonomic shifts between diseased and healthy patients, genetic variants are an important consideration in the predictive quality of disease and treatment decisions. The comparison between interactions of microbial populations and treatment in addition to the role of genetic variants may provide insight into treatment non-responders. Due to our limitations in current knowledge including the complexity of the microcosm, ethnic genetic variations among human populations, and our focus on relevant articles published in English over the past six years, we may have missed relevant studies. Future studies should focus on the comparison between Western and other cultural populations as well as further implementation of Genome-Wide Association Studies (GWAS) in clinical predictability.
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Affiliation(s)
| | - Jashvini Amirthalingam
- Neurology, California Institute of Behavioral Neurosciences & Psychology, Fairfield, USA
| | - Khadija Alshowaikh
- Obstetrics and Gynecology, California Institute of Behavioral Neurosciences & Psychology, Fairfield , USA
| | | | | | - Gokul Paidi
- Internal Medicine, California Institute of Behavioral Neurosciences & Psychology, Fairfield, USA
| | - Huseyin Ekin Ergin
- General Practice, California Institute of Behavioral Neurosciences & Psychology, Fairfield, USA
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Nelson A, Stewart CJ, Kennedy NA, Lodge JK, Tremelling M, Probert CS, Parkes M, Mansfield JC, Smith DL, Hold GL, Lees CW, Bridge SH, Lamb CA. The Impact of NOD2 Genetic Variants on the Gut Mycobiota in Crohn's Disease Patients in Remission and in Individuals Without Gastrointestinal Inflammation. J Crohns Colitis 2021; 15:800-812. [PMID: 33119074 PMCID: PMC8095387 DOI: 10.1093/ecco-jcc/jjaa220] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND AIMS Historical and emerging data implicate fungi in Crohn's disease [CD] pathogenesis. However, a causal link between mycobiota, dysregulated immunity, and any impact of NOD2 variants remains elusive. This study aims to evaluate associations between NOD2 variants and faecal mycobiota in CD patients and non-CD subjects. METHODS Faecal samples were obtained from 34 CD patients [18 NOD2 mutant, 16 NOD2 wild-type] identified from the UK IBD Genetics Consortium. To avoid confounding influence of mucosal inflammation, CD patients were in clinical remission and had a faecal calprotectin <250 μg/g; 47 non-CD subjects were included as comparator groups, including 22 matched household [four NOD2 mutant] and 25 non-household subjects with known NOD2 genotype [14 NOD2 mutant] identified by the NIHR BioResource Cambridge. Faecal mycobiota composition was determined using internal transcribed spacer 1 [ITS1] sequencing and was compared with 16S rRNA gene sequences and volatile organic compounds. RESULTS CD was associated with higher numbers of fungal observed taxonomic units [OTUs] [p = 0.033]. Principal coordinates analysis using Jaccard index [p = 0.018] and weighted Bray-Curtis dissimilarities [p = 0.01] showed Candida spp. clustered closer to CD patients whereas Cryptococcus spp. clustered closer to non-CD. In CD, we found higher relative abundance of Ascomycota [p = 0.001] and lower relative abundance Basidiomycota [p = 0.019] phyla. An inverse relationship was found between bacterial and fungal Shannon diversity in NOD2 wild-type which was independent of CD [r = -0.349; p = 0.029]. CONCLUSIONS This study confirms compositional changes in the gut mycobiota in CD and provides evidence that fungi may play a role in CD pathogenesis. No NOD2 genotype-specific differences were observed in the faecal mycobiota.
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Affiliation(s)
- Andrew Nelson
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - Christopher J Stewart
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Nicholas A Kennedy
- IBD Pharmacogenetics Group, University of Exeter, Exeter, UK
- Department of Gastroenterology, Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
| | - John K Lodge
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - Mark Tremelling
- Department of Gastroenterology, Norfolk and Norwich University Hospitals NHS Foundation Trust, Norwich, UK
| | | | - Chris S Probert
- Institute of Translational Medicine, University of Liverpool, Liverpool, UK
- Department of Gastroenterology, Liverpool University Hospitals NHS Foundation Trust, Liverpool, UK
| | - Miles Parkes
- Department of Gastroenterology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | - John C Mansfield
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
- Department of Gastroenterology, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Darren L Smith
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
| | - Georgina L Hold
- Gastrointestinal Research Group, University of Aberdeen, Aberdeen, UK
- Microbiome Research Centre, St George and Sutherland Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Charlie W Lees
- Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, UK
- Edinburgh IBD Unit, Western General Hospital, Edinburgh, UK
| | - Simon H Bridge
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Christopher A Lamb
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK
- Department of Gastroenterology, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
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Aldars-García L, Chaparro M, Gisbert JP. Systematic Review: The Gut Microbiome and Its Potential Clinical Application in Inflammatory Bowel Disease. Microorganisms 2021; 9:microorganisms9050977. [PMID: 33946482 PMCID: PMC8147118 DOI: 10.3390/microorganisms9050977] [Citation(s) in RCA: 69] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 04/22/2021] [Accepted: 04/29/2021] [Indexed: 02/07/2023] Open
Abstract
Inflammatory bowel disease (IBD) is a chronic relapsing-remitting systemic disease of the gastrointestinal tract. It is well established that the gut microbiome has a profound impact on IBD pathogenesis. Our aim was to systematically review the literature on the IBD gut microbiome and its usefulness to provide microbiome-based biomarkers. A systematic search of the online bibliographic database PubMed from inception to August 2020 with screening in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted. One-hundred and forty-four papers were eligible for inclusion. There was a wide heterogeneity in microbiome analysis methods or experimental design. The IBD intestinal microbiome was generally characterized by reduced species richness and diversity, and lower temporal stability, while changes in the gut microbiome seemed to play a pivotal role in determining the onset of IBD. Multiple studies have identified certain microbial taxa that are enriched or depleted in IBD, including bacteria, fungi, viruses, and archaea. The two main features in this sense are the decrease in beneficial bacteria and the increase in pathogenic bacteria. Significant differences were also present between remission and relapse IBD status. Shifts in gut microbial community composition and abundance have proven to be valuable as diagnostic biomarkers. The gut microbiome plays a major role in IBD, yet studies need to go from casualty to causality. Longitudinal designs including newly diagnosed treatment-naïve patients are needed to provide insights into the role of microbes in the onset of intestinal inflammation. A better understanding of the human gut microbiome could provide innovative targets for diagnosis, prognosis, treatment and even cure of this relevant disease.
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Affiliation(s)
- Laila Aldars-García
- Hospital Universitario de La Princesa, Instituto de Investigación Sanitaria Princesa (IIS-IP), Universidad Autónoma de Madrid, 28006 Madrid, Spain; (L.A.-G.); (M.C.)
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), 28006 Madrid, Spain
| | - María Chaparro
- Hospital Universitario de La Princesa, Instituto de Investigación Sanitaria Princesa (IIS-IP), Universidad Autónoma de Madrid, 28006 Madrid, Spain; (L.A.-G.); (M.C.)
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), 28006 Madrid, Spain
| | - Javier P. Gisbert
- Hospital Universitario de La Princesa, Instituto de Investigación Sanitaria Princesa (IIS-IP), Universidad Autónoma de Madrid, 28006 Madrid, Spain; (L.A.-G.); (M.C.)
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), 28006 Madrid, Spain
- Correspondence: ; Tel.: +34-913-093-911; Fax: +34-915-204-013
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Dang JT, Dang TT, Wine E, Dicken B, Madsen K, Laffin M. The Genetics of Postoperative Recurrence in Crohn Disease: A Systematic Review, Meta-analysis, and Framework for Future Work. Crohns Colitis 360 2021; 3:otaa094. [PMID: 36778938 PMCID: PMC9802308 DOI: 10.1093/crocol/otaa094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Indexed: 12/12/2022] Open
Abstract
Background Recurrence following abdominal surgery in Crohn disease is over 50%. The impact of genetics on postoperative recurrence is not well defined. Methods A literature search was conducted where inclusion required an assessment, by genotype, of postoperative recurrence. The primary endpoint was odds of surgical recurrence. Results Twenty-eight studies identified a total of 6715 patients. Thirteen loci were identified as modifying the risk of recurrence. NOD2 was identified as a risk factor for recurrence by multiple works (cumulative odds ratio: 1.64, P = 0.003). Conclusions A NOD2 risk allele is associated with recurrence following surgery in Crohn disease. Progress in this area will require standardized reporting in future works.
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Affiliation(s)
- Jerry T Dang
- Department of Surgery, University of Alberta, Edmonton, Alberta, Canada
| | - ThucNhi T Dang
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Eytan Wine
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Bryan Dicken
- Department of Surgery, University of Alberta, Edmonton, Alberta, Canada
| | - Karen Madsen
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Michael Laffin
- Department of Surgery, University of Alberta, Edmonton, Alberta, Canada,Address correspondence to: Michael Laffin, MD, PhD, Department of Surgery, University of Alberta, University of Alberta Hospital, 8440 112 Street NW, Edmonton, AB T6G 2B7, Canada ()
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Abstract
The oral cavity is continuous with the gastrointestinal tract and in children, oral health may be closely linked with the overall health of the GI tract. In the case of pediatric Crohn's disease (CD), oral manifestations are an important clinical indicator of intestinal disease. Recent studies of the microbiome in IBD suggest that translocation of oral microbes to the gut may be a common feature of the microbial dysbiosis which is a signature of both CD and ulcerative colitis (UC). Murine studies suggest that translocation of oral bacteria and yeasts to the lower GI tract may trigger inflammation in susceptible hosts, providing a mechanistic link to the development of IBD. Conversely, some studies have shown that dysbiosis of the oral microbiome may occur, possibly as a result of inflammatory responses and could represent a useful source of biomarkers of GI health. This review summarizes our current knowledge of the oral microbiome in IBD and presents current hypotheses on the potential role of this community in the pathogenesis of these diseases.
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Affiliation(s)
- Khalid Elmaghrawy
- School of Dental Science, Trinity College Dublin and Dublin Dental University Hospital, Dublin, Ireland
| | - Séamus Hussey
- Department of Paediatrics, University of Medicine and Health Sciences, Royal College of Surgeons in Ireland, Dublin, Ireland
- National Children's Research Centre, Dublin, Ireland
| | - Gary P. Moran
- School of Dental Science, Trinity College Dublin and Dublin Dental University Hospital, Dublin, Ireland
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Affiliation(s)
| | - A.S. Hedayat
- Department of Mathematics, Statistics, and Computer Science, University of Illinois at Chicago, Chicago, IL
| | - Min Yang
- Department of Mathematics, Statistics, and Computer Science, University of Illinois at Chicago, Chicago, IL
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Abstract
The Paneth cells reside in the small intestine at the bottom of the crypts of Lieberkühn, intermingled with stem cells, and provide a niche for their neighbors by secreting growth and Wnt-factors as well as different antimicrobial peptides including defensins, lysozyme and others. The most abundant are the human Paneth cell α-defensin 5 and 6 that keep the crypt sterile and control the local microbiome. In ileal Crohn's disease various mechanisms including established genetic risk factors contribute to defects in the production and ordered secretion of these peptides. In addition, life-style risk factors for Crohn's disease like tobacco smoking also impact on Paneth cell function. Taken together, current evidence suggest that defective Paneth cells may play the key role in initiating inflammation in ileal, and maybe ileocecal, Crohn's disease by allowing bacterial attachment and invasion.
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Affiliation(s)
- Jan Wehkamp
- University of Tübingen, Medizinische Klinik I, Tübingen, Germany
| | - Eduard F Stange
- University of Tübingen, Medizinische Klinik I, Tübingen, Germany
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Abstract
Introduction: Inflammatory bowel diseases (IBD) are on the rise worldwide. This review covers the current concepts of the etiology of Crohn´s disease and ulcerative colitis by focusing on an unbalanced interaction between the intestinal microbiota and the mucosal barrier. Understanding these issues is of paramount importance for the development of targeted therapies aiming at the disease cause.Area covered: Gut microbiota alterations and a dysfunctional intestinal mucosa are associated with IBD. Here we focus on specific defense structures of the mucosal barrier, namely antimicrobial peptides and the mucus layer, which keep the gut microbiota at a distance under healthy conditions and are defective in IBD.Expert commentary: The microbiology of both forms of IBD is different but characterized by a reduced bacterial diversity and richness. Abundance of certain bacterial species is altered, and the compositional changes are related to disease activity. In IBD the mucus layer above the epithelium is contaminated by bacteria and the immune reaction is dominated by the antibacterial response. Human genetics suggest that many of the basic deficiencies in the mucosal response, due to Paneth cell, defensin and mucus defects, are primary. Nutrition may also be important but so far there is no therapy targeting the mucosal barrier.
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Affiliation(s)
- Eduard F Stange
- Innere Medizin I, Medizinische Universitätsklinik, Tübingen, Germany
| | - Bjoern O Schroeder
- Laboratory for Molecular Infection Medicine Sweden (MIMS) -The Nordic EMBL Partnership for Molecular Medicine, and Department of Molecular Biology, Umeå University, Umeå, Sweden
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