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Irritable Bowel Syndrome: HELP
Articles by Magnus Simrén
Based on 95 articles published since 2008
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Between 2008 and 2019, M. Simren wrote the following 95 articles about Irritable Bowel Syndrome.
 
+ Citations + Abstracts
Pages: 1 · 2 · 3 · 4
1 Guideline Intestinal microbiota in functional bowel disorders: a Rome foundation report. 2013

Simrén, Magnus / Barbara, Giovanni / Flint, Harry J / Spiegel, Brennan M R / Spiller, Robin C / Vanner, Stephen / Verdu, Elena F / Whorwell, Peter J / Zoetendal, Erwin G / Anonymous5360729. ·Department of Internal Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg S-41345, Sweden. magnus.simren@medicine.gu.se ·Gut · Pubmed #22730468.

ABSTRACT: It is increasingly perceived that gut host-microbial interactions are important elements in the pathogenesis of functional gastrointestinal disorders (FGID). The most convincing evidence to date is the finding that functional dyspepsia and irritable bowel syndrome (IBS) may develop in predisposed individuals following a bout of infectious gastroenteritis. There has been a great deal of interest in the potential clinical and therapeutic implications of small intestinal bacterial overgrowth in IBS. However, this theory has generated much debate because the evidence is largely based on breath tests which have not been validated. The introduction of culture-independent molecular techniques provides a major advancement in our understanding of the microbial community in FGID. Results from 16S rRNA-based microbiota profiling approaches demonstrate both quantitative and qualitative changes of mucosal and faecal gut microbiota, particularly in IBS. Investigators are also starting to measure host-microbial interactions in IBS. The current working hypothesis is that abnormal microbiota activate mucosal innate immune responses which increase epithelial permeability, activate nociceptive sensory pathways and dysregulate the enteric nervous system. While we await important insights in this field, the microbiota is already a therapeutic target. Existing controlled trials of dietary manipulation, prebiotics, probiotics, synbiotics and non-absorbable antibiotics are promising, although most are limited by suboptimal design and small sample size. In this article, the authors provide a critical review of current hypotheses regarding the pathogenetic involvement of microbiota in FGID and evaluate the results of microbiota-directed interventions. The authors also provide clinical guidance on modulation of gut microbiota in IBS.

2 Editorial Editorial: subgroups in irritable bowel syndrome-more than just diarrhoea and constipation? Authors' reply. 2017

Polster, A / Van Oudenhove, L / Jones, M / Öhman, L / Törnblom, H / Simrén, M. ·Department of Internal Medicine and Clinical Nutrition, Sahlgrenska Academy, Gothenburg, Sweden. · Translational Research Center for Gastrointestinal Disorders (TARGID), Leuven, Belgium. · Psychology Department, Macquarie University, North Ryde, NSW, Australia. · Department of Microbiology and Immunology, Sahlgrenska Academy, Gothenburg, Sweden. · Center for Functional Gastrointestinal and Motility Disorders, Chapel Hill, NC, USA. ·Aliment Pharmacol Ther · Pubmed #28880440.

ABSTRACT: -- No abstract --

3 Editorial Irritable bowel syndrome: what do the new Rome IV diagnostic guidelines mean for patient management? 2017

Whitehead, William E / Palsson, Olafur S / Simrén, Magnus. ·a Division of Gastroenterology Hepatology, Centre of Functional Gastrointestinal & Motility Disorders , University of North Carolina Chapel Hill , Chapel Hill , NC , USA. · b Gastroenterology , Sahlgrenska University Hospital , Gothenburg , Sweden. ·Expert Rev Gastroenterol Hepatol · Pubmed #28276814.

ABSTRACT: -- No abstract --

4 Editorial Diet as a therapy for irritable bowel syndrome: progress at last. 2014

Simrén, Magnus. ·Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; University of Gothenburg Centre for Person-Centred Care, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. Electronic address: magnus.simren@medicine.gu.se. ·Gastroenterology · Pubmed #24275241.

ABSTRACT: -- No abstract --

5 Editorial Bloating and abdominal distention: not so poorly understood anymore! 2009

Simrén, Magnus. · ·Gastroenterology · Pubmed #19327731.

ABSTRACT: -- No abstract --

6 Review Colonic immune cells in irritable bowel syndrome: A systematic review and meta-analysis. 2018

Bashashati, M / Moossavi, S / Cremon, C / Barbaro, M R / Moraveji, S / Talmon, G / Rezaei, N / Hughes, P A / Bian, Z X / Choi, C H / Lee, O Y / Coëffier, M / Chang, L / Ohman, L / Schmulson, M J / McCallum, R W / Simren, M / Sharkey, K A / Barbara, G. ·Division of Gastroenterology, Department of Internal Medicine, Texas Tech University Health Sciences Center/Paul L. Foster School of Medicine, El Paso, TX, USA. · Digestive Oncology Research Center, Digestive Disease Research Institute, Tehran University of Medical Sciences, Tehran, Iran. · Department of Medical Microbiology, University of Manitoba, Winnipeg, MB, Canada. · Department of Medical and Surgical Sciences, Centre for Applied Biomedical Research, University of Bologna, Bologna, Italy. · Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA. · Fred and Pamela Buffet Cancer Center, Omaha, NE, USA. · Research Center for Immunodeficiencies, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran. · Centre for Nutritional and Gastrointestinal Diseases, Department of Medicine, University of Adelaide and South Australian Health Medical Health Research Institute, Adelaide, SA, Australia. · School of Chinese Medicine, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, China. · Department of Internal Medicine, Chung-Ang University College of Medicine, Seoul, Korea. · Department of Internal Medicine, Hanyang University College of Medicine, Seoul, Korea. · Normandie Univ, INSERM unit 1073 "Nutrition, inflammation and brain-gut axis", Institute for Research and Innovation in Biomedicine, Rouen Medical University and Rouen University Hospital, Rouen, France. · G Oppenheimer Center of Neurobiology of Stress and Resilience, David Geffen School of Medicine, University of California, Los Angeles, CA, USA. · Departments of Internal Medicine and Clinical Nutrition and Microbiology and Immunology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. · Laboratorio de Hígado, Páncreas y Motilidad (HIPAM), Unidad de Investigación en Medicina Experimental, Facultad de Medicina-Universidad Nacional Autónoma de México (UNAM), Hospital General de México, Mexico City, Mexico. · Department of Internal Medicine & Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. · Center for Functional GI and Motility Disorders, University of North Carolina, Chapel Hill, NC, USA. · Hotchkiss Brain Institute and Snyder Institute for Chronic Diseases, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada. ·Neurogastroenterol Motil · Pubmed #28851005.

ABSTRACT: BACKGROUND & AIMS: Increases in mucosal immune cells have frequently been observed in irritable bowel syndrome (IBS) patients. However, this finding is not completely consistent between studies, possibly due to a combination of methodological variability, population differences and small sample sizes. We performed a meta-analysis of case-control studies that compared immune cell counts in colonic biopsies of IBS patients and controls. METHODS: PubMed and Embase were searched in February 2017. Results were pooled using standardized mean difference (SMD) and were considered significant when zero was not within the 95% confidence interval (CI). Heterogeneity was assessed based on I KEY RESULTS: Twenty-two studies on 706 IBS patients and 401 controls were included. Mast cells were increased in the rectosigmoid (SMD: 0.38 [95% CI: 0.06-0.71]; P = .02) and descending colon (SMD: 1.69 [95% CI: 0.65-2.73]; P = .001) of IBS patients. Increased mast cells were observed in both constipation (IBS-C) and diarrhea predominant IBS (IBS-D). CD3 CONCLUSIONS & INFERENCES: Mast cells and CD3

7 Review Understanding the Gut Microbiota in Inflammatory and Functional Gastrointestinal Diseases. 2017

Sundin, Johanna / Öhman, Lena / Simrén, Magnus. ·From the Departments of Internal Medicine and Clinical Nutrition, Institute of Medicine (Sundin, Öhman, Simrén) and Microbiology and Immunology (Sundin, Öhman), Sahlgrenska Academy at University of Gothenburg, Sweden · School of Health and Education (Öhman), University of Skövde, Sweden · and Center for Functional GI and Motility Disorders (Simrén), University of North Carolina, Chapel Hill, North Carolina. ·Psychosom Med · Pubmed #28422780.

ABSTRACT: OBJECTIVE: During the last decade, experimental and observational studies have shown that patients with inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) may have an altered intestinal microbial composition compared with healthy individuals. However, no uniform microbial signature has as yet been detected for either IBD or IBS. This review summarizes the current knowledge of microbial dysbiosis and its potential relationship to the pathophysiology in IBD and IBS. METHODS: A selective review was conducted to summarize the current knowledge of gut microbiota in the pathophysiology of IBD and IBS. RESULTS: Experimental and observational studies provide good evidence for intestinal microbial dysbiosis in subgroups of IBD and IBS. Still, no uniform disease pattern has been detected. This is most likely due to the heterogeneous nature of IBD and IBS, in combination with the effects of intrinsic and extrinsic factors. Such intrinsic factors include genetics, the gastrointestinal environment, and the host immune system, whereas extrinsic factors include early life diet, breastfeeding, and method of infant delivery. CONCLUSIONS: Recent and ongoing work to define microbial dysbiosis in IBD and IBS shows promise, but future well-designed studies with well-characterized study individuals are needed. It is likely that the microbial dysbiosis in IBD and IBS is dependent on the natural disease course of IBD and symptom pattern in IBS. Therefore, assessment of the entire microbiota along the gastrointestinal tract, in relationship to confounding factors, symptom fluctuations, and other pathophysiological factors, is needed for further understanding of the etiology of these common diseases.

8 Review Management of the multiple symptoms of irritable bowel syndrome. 2017

Simrén, Magnus / Törnblom, Hans / Palsson, Olafur S / Whitehead, William E. ·Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; Center for Functional Gastrointestinal and Motility Disorders, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. Electronic address: magnus.simren@medicine.gu.se. · Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. · Center for Functional Gastrointestinal and Motility Disorders, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. ·Lancet Gastroenterol Hepatol · Pubmed #28403981.

ABSTRACT: Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders. A stepwise management approach is advocated for patients with IBS. For a substantial proportion of patients with mild symptoms, general management principles, including making a confident diagnosis and offering explanation, reassurance, and dietary and lifestyle advice, are sufficient. However, many patients continue to have moderate-to-severe symptoms and are not satisfied solely with this approach. In these patients, use of pharmacotherapy on the basis of the predominant symptom (constipation, diarrhoea, pain, or bloating) or combination of symptoms is the next step. For patients with symptoms that are refractory to these initial treatment options and those who have comorbid conditions or psychological symptoms, a combination of therapies should be used, and the use of psychotropic drugs and psychological treatment alternatives is often effective. Finally, the key to successful treatment of patients with IBS is a good physician-patient relationship and use of person-centred care principles.

9 Review Update on Rome IV Criteria for Colorectal Disorders: Implications for Clinical Practice. 2017

Simren, Magnus / Palsson, Olafur S / Whitehead, William E. ·Department of Internal Medicine & Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, 40530, Gothenburg, Sweden. magnus.simren@medicine.gu.se. · Center for Functional Gastrointestinal and Motility Disorders, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. magnus.simren@medicine.gu.se. · Center for Functional Gastrointestinal and Motility Disorders, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. ·Curr Gastroenterol Rep · Pubmed #28374308.

ABSTRACT: PURPOSE OF REVIEW: The purpose of the review was to provide an update of the Rome IV criteria for colorectal disorders with implications for clinical practice. RECENT FINDINGS: The Rome diagnostic criteria are expert consensus criteria for diagnosing functional gastrointestinal disorders (FGIDs). The current version, Rome IV, was released in May of 2016 after Rome III had been in effect for a decade. It is the collective product of committees that included more than 100 leading functional GI experts. For functional bowel and anorectal disorders, the majority of changes relative to Rome III are relatively minor and will have little impact on clinical practice. However, notable changes with potential impact on clinical practice and research include the changes in the diagnostic criteria for IBS, the modified approach for subtyping of IBS, the view on functional bowel disorders as a spectrum of disorders, and the new definition of fecal incontinence. New features in the Rome IV diagnostic criteria for functional bowel and anorectal disorders will likely have modest influence on clinical practice, with a few exceptions.

10 Review Small intestinal bacterial overgrowth as a cause for irritable bowel syndrome: guilty or not guilty? 2017

Aziz, Imran / Törnblom, Hans / Simrén, Magnus. ·Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. ·Curr Opin Gastroenterol · Pubmed #28257307.

ABSTRACT: PURPOSE OF REVIEW: Small intestinal bacterial overgrowth (SIBO) has been proposed as a cause of irritable bowel syndrome (IBS). However, this relationship has been subject to controversy. This review aims to provide a current perspective on the SIBO-IBS hypothesis. RECENT FINDINGS: Case-control studies evaluating the prevalence of SIBO in IBS and healthy individuals have shown conflicting results. Moreover, the tests available in routine clinical practice to diagnose SIBO are not valid and lack both sensitivity and specificity. Hence, interpreting the effect of interventions based on these tests is fraught with uncertainty. Furthermore, the SIBO-IBS hypothesis has paved the way to assess antibiotic therapy in nonconstipated IBS, with rifaximin, a nonabsorbable antibiotic, showing modest but significant clinical benefit. However, individuals were not tested for SIBO and the mechanism of action of rifaximin in IBS remains to be elucidated. Preliminary data suggest that rifaximin decreases microbial richness and previous studies have noted antibacterial interventions in IBS to reduce colonic fermentation and improve symptoms. The advent of rapid culture-independent molecular techniques is a promising tool that will seek to clarify and advance our understanding of the gut microbial function. SUMMARY: The SIBO-IBS hypothesis lacks convincing evidence but remains under scrutiny. The mechanism resulting in symptom improvement after rifaximin treatment in some IBS individuals requires exploration. Novel molecular techniques provide an exciting and challenging opportunity to explore the host-gut microbiota interaction.

11 Review Phenotyping of subjects for large scale studies on patients with IBS. 2016

Boeckxstaens, G E / Drug, V / Dumitrascu, D / Farmer, A D / Hammer, J / Hausken, T / Niesler, B / Pohl, D / Pojskic, L / Polster, A / Simren, M / Goebel-Stengel, M / Van Oudenhove, L / Vassallo, M / Wensaas, K-A / Aziz, Q / Houghton, L A / Anonymous3490872. ·Translational Research Center for Gastrointestinal Disorders, KULeuven & Department of Gastroenterology and Hepatology, University Hospital Leuven, Leuven, Belgium. · Gastroenterology Department, University Hospital "St Spiridon", Gr. T.Popa University of Medicine and Pharmacy, Iasi, Romania. · 2nd Medical Dept., Iuliu Hatieganu University of Medicine and Pharmacy, Cluj-Napoca, Romania. · Wingate Institute of Neurogastroenterology, Barts and The London School of Medicine and Dentistry, London, UK. · Department of Gastroenterology, University Hospitals of North Midlands, Stoke on Trent, UK. · Medizinische Universität Wien, Universitätsklinik für Innere Medizin 3, Vienna, Austria. · Department of Medicine, Unit of Gastroenterology, Haukeland University Hospital, Bergen, Norway. · Department of Human Molecular Genetics, University of Heidelberg, Heidelberg, Germany. · Division of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland. · Institute for Genetic Engineering and Biotechnology, University of Sarajevo, Sarajevo, Bosnia and Herzegovina. · Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. · Center for Functional Gastrointestinal and Motility Disorders, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. · Department of Internal Medicine, Martin-Luther-Krankenhaus, Berlin, Germany. · Department of Medicine, Mater Dei Hospital, Tal-Qroqq, Malta. · Uni Research Health, Research Unit for General Practice, Bergen, Norway. · Leeds Institute of Biomedical and Clinical Sciences, University of Leeds and Leeds Gastroenterology Institute, Leeds Teaching Hospitals Trust, Leeds, UK. · Centre for Gastrointestinal Sciences, University of Manchester, Manchester, UK. · Division of Gastroenterology and Hepatology, Mayo Clinic, Jacksonville, FL, USA. ·Neurogastroenterol Motil · Pubmed #27319981.

ABSTRACT: BACKGROUND: Irritable bowel syndrome (IBS) is a complex condition with multiple factors contributing to its aetiology and pathophysiology. Aetiologically these include genetics, life-time events and environment, and physiologically, changes in motility, central processing, visceral sensitivity, immunity, epithelial permeability and gastrointestinal microflora. Such complexity means there is currently no specific reliable biomarker for IBS, and thus IBS continues to be diagnosed and classified according to symptom based criteria, the Rome Criteria. Carefully phenotyping and characterisation of a 'large' pool of IBS patients across Europe and even the world however, might help identify sub-populations with accuracy and consistency. This will not only aid future research but improve tailoring of treatment and health care of IBS patients. PURPOSE: The aim of this position paper is to discuss the requirements necessary to standardize the process of selecting and phenotyping IBS patients and how to organise the collection and storage of patient information/samples in such a large multi-centre pan European/global study. We include information on general demographics, gastrointestinal symptom assessment, psychological factors, quality of life, physiological evaluation, genetic/epigenetic and microbiota analysis, biopsy/blood sampling, together with discussion on the organisational, ethical and language issues associated with implementing such a study. The proposed approach and documents selected to be used in such a study was the result of a thoughtful and thorough four-year dialogue amongst experts associated with the European COST action BM1106 GENIEUR (www.GENIEUR.eu).

12 Review Biomarkers to distinguish functional constipation from irritable bowel syndrome with constipation. 2016

Whitehead, W E / Palsson, O S / Simrén, M. ·Center for Functional Gastrointestinal and Motility Disorders, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. · Department of Internal Medicine & Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. ·Neurogastroenterol Motil · Pubmed #27214096.

ABSTRACT: Treatments for functional constipation (FC) and irritable bowel syndrome with constipation (IBS-C) differ, but symptom criteria do not reliably distinguish between them; some regard FC and IBS-C as parts of a single constipation spectrum. Our goal was to review studies comparing FC and IBS-C to identify possible biomarkers that separate them. A systematic review identified 15 studies that compared physiologic tests in FC vs IBS-C. Pain thresholds were lower in IBS-C than FC for 3/5 studies and not different in 2/5. Colonic motility was decreased more in FC than IBS-C for 3/3 studies, and whole gut transit was delayed more in FC than IBS-C in 3/8 studies and not different in 5/8. Pelvic floor dyssynergia was unrelated to diagnosis. Sympathetic arousal, measured in only one study, was greater in IBS-C than FC. The most reliable separation of FC from IBS-C was shown by a novel new magnetic resonance imaging technique described in this issue of the journal. These authors showed that drinking one liter of polyethylene glycol laxative significantly increased water content in the small intestine, volume of contents in the ascending colon, and time to first evacuation in FC vs IBS-C; and resulted in less colon motility and delayed whole gut transit in FC compared to IBS-C. Although replication is needed, this well-tolerated, non-invasive test promises to become a new standard for differential diagnosis of FC vs IBS-C. These data suggest that FC and IBS-C are different disorders rather than points on a constipation spectrum.

13 Review Irritable bowel syndrome. 2016

Enck, Paul / Aziz, Qasim / Barbara, Giovanni / Farmer, Adam D / Fukudo, Shin / Mayer, Emeran A / Niesler, Beate / Quigley, Eamonn M M / Rajilić-Stojanović, Mirjana / Schemann, Michael / Schwille-Kiuntke, Juliane / Simren, Magnus / Zipfel, Stephan / Spiller, Robin C. ·Department of Internal Medicine VI (Psychosomatic Medicine and Psychotherapy), University Hospital Tübingen, Tübingen, Germany. · Wingate Institute of Neurogastroenterology, Barts and London School of Medicine and Dentistry, Queen Mary University of London, London, UK. · Department of Medical and Surgical Sciences, St. Orsola-Malpighi Hospital, Bologna, Italy. · Department of Behavioural Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan. · Oppenheimer Center for Neurobiology of Stress, Division of Digestive Diseases, David Geffen School of Medicine at UCLA, Los Angeles, California, USA. · Department of Human Molecular Genetics, University of Heidelberg, Heidelberg, Germany. · Lynda K and David M Underwood Center for Digestive Disorders, Division of Gastroenterology and Hepatology, Houston Methodist Hospital, Weill Cornell Medical College, Houston, Texas, USA. · Department of Biochemical Engineering and Biotechnology, Faculty of Technology and Metallurgy, University of Belgrade, Belgrade, Serbia. · Department of Human Biology, Technical University Munich, Freising-Weihenstephan, Germany. · Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. · NIHR Nottingham Digestive Diseases Biomedical Research Unit, University of Nottingham, Nottingham, UK. ·Nat Rev Dis Primers · Pubmed #27159638.

ABSTRACT: Irritable bowel syndrome (IBS) is a functional gastrointestinal disease with a high population prevalence. The disorder can be debilitating in some patients, whereas others may have mild or moderate symptoms. The most important single risk factors are female sex, younger age and preceding gastrointestinal infections. Clinical symptoms of IBS include abdominal pain or discomfort, stool irregularities and bloating, as well as other somatic, visceral and psychiatric comorbidities. Currently, the diagnosis of IBS is based on symptoms and the exclusion of other organic diseases, and therapy includes drug treatment of the predominant symptoms, nutrition and psychotherapy. Although the underlying pathogenesis is far from understood, aetiological factors include increased epithelial hyperpermeability, dysbiosis, inflammation, visceral hypersensitivity, epigenetics and genetics, and altered brain-gut interactions. IBS considerably affects quality of life and imposes a profound burden on patients, physicians and the health-care system. The past decade has seen remarkable progress in our understanding of functional bowel disorders such as IBS that will be summarized in this Primer.

14 Review Practical management of irritable bowel syndrome: a clinical review. 2016

Almquist, Ellinor / Törnblom, Hans / Simrén, Magnus. ·Department of Internal Medicine & Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden - ellinor.almquist@gmail.com. ·Minerva Gastroenterol Dietol · Pubmed #26448307.

ABSTRACT: Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder, frequently managed by general practitioners and gastroenterologists. It is a complex condition, characterized by abdominal pain or discomfort associated with altered bowel habits, and it affects 11% of the population worldwide. It has a profound effect on quality of life for many patients and poses a substantial cost to society. Due to the complexity and diversity of IBS, diagnosis and treatment can be challenging. Common drawbacks in diagnosing and treating this disorder include unnecessary tests, failure to establish trust in the physician-patient relationship and difficulties in explaining the diagnosis. Research in recent years has however refined the diagnostic criteria and improved our ability to safely identify IBS with a limited number of investigations. A concise diagnostic evaluation, guided adequate information, prompt initiation of symptom-guided treatment and consistency in the patient-doctor relationship can help relieve the suffering experienced by patients with IBS. For patients with mild symptoms, reassurance, education, lifestyle changes and dietary advice are often sufficient. Patients with moderate to severe symptoms might need symptom modifying drugs, and psychological treatments such as CBT or hypnotherapy may be offered at this stage. For patients with severe and incapacitating symptoms, a multidisciplinary approach is recommended and psychotropic drugs are often used. This clinical review offers suggestions for a diagnostic approach as well as a treatment strategy, based on the current evidence on pathophysiology, diagnosis and treatment in IBS.

15 Review Gut microbiota as potential orchestrators of irritable bowel syndrome. 2015

Bennet, Sean M P / Ohman, Lena / Simren, Magnus. ·Departments of Internal Medicine and Clinical Nutrition, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. ·Gut Liver · Pubmed #25918261.

ABSTRACT: Irritable bowel syndrome (IBS) is a multifactorial functional disorder with no clearly defined etiology or pathophysiology. Modern culture-independent techniques have improved the understanding of the gut microbiota's composition and demonstrated that an altered gut microbiota profile might be found in at least some subgroups of IBS patients. Research on IBS from a microbial perspective is gaining momentum and advancing. This review will therefore highlight potential links between the gut microbiota and IBS by discussing the current knowledge of the gut microbiota; it will also illustrate bacterial-host interactions and how alterations to these interactions could exacerbate, induce or even help alleviate IBS.

16 Review Crosstalk at the mucosal border: importance of the gut microenvironment in IBS. 2015

Öhman, Lena / Törnblom, Hans / Simrén, Magnus. ·Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, 41345 Gothenburg, Sweden. ·Nat Rev Gastroenterol Hepatol · Pubmed #25446728.

ABSTRACT: The aetiology and pathology of IBS, a functional bowel disorder thought to lack an organic cause, is largely unknown. However, studies suggest that various features, such as altered composition of the gut microbiota, together with increased intestinal permeability, a changed balance in the enteroendocrine system and a dysregulated immune system in the gut, most likely have an important role in IBS. Exactly how these entities act together and give rise to symptoms is still unknown, but an altered gut microbiota composition could lead to dysregulation of the intestinal barrier as well as the enteroendocrine and the immune systems, which (through interactions with the nervous system) might generate symptoms. This Review highlights the crosstalk between the gut microbiota, the enteroendocrine system, the immune system and the role of intestinal permeability in patients with IBS.

17 Review Cytokine imbalance in irritable bowel syndrome: a systematic review and meta-analysis. 2014

Bashashati, M / Rezaei, N / Shafieyoun, A / McKernan, D P / Chang, L / Öhman, L / Quigley, E M / Schmulson, M / Sharkey, K A / Simrén, M. ·Department of Physiology and Pharmacology, Snyder Institute for Chronic Diseases and Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada. ·Neurogastroenterol Motil · Pubmed #24796536.

ABSTRACT: BACKGROUND: Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder of unknown etiology; although infection and inflammation have recently been considered as important etiologic agents. A recent meta-analysis showed correlations between cytokine [interleukin-10 (IL-10) and tumor necrosis factor (TNF)] gene polymorphisms and IBS; however, it is still unknown whether patients with IBS have different cytokine profiles compared to healthy population. METHODS: To determine the relationships between serum/plasma levels or mucosal expression of IL-10/TNF-α and IBS, we conducted a systematic review and meta-analysis based on case-control studies retrieved from PubMed and EMBASE search through August 2013. Standardized mean difference (SMD) was generated by using the inverse variance method. Heterogeneity was assessed based on I(2) values. KEY RESULTS: Serum/plasma levels of TNF-α tended to be higher in IBS vs controls (p = 0.09); this reached significance in IBS subtypes vs controls and in female patients with IBS. However, serum/plasma levels of IL-10 were not significantly different in IBS patients vs controls. Further analysis of serum/plasma IL-10 levels in IBS subtypes did not show any difference; however, analysis based on gender showed a significantly lower serum/plasma IL-10 levels in male patients with IBS vs male controls (p = 0.02). Colonic IL-10 mRNA had a significantly lower expression in IBS vs control (p = 0.001). CONCLUSIONS & INFERENCES: There is an imbalance of proinflammatory TNF-α, and anti-inflammatory IL-10, cytokines in IBS. Stratifying IBS patients based on cytokine profile may represent an opportunity for personalized treatment of this condition.

18 Review Intestinal microbiota and its role in irritable bowel syndrome (IBS). 2013

Ohman, Lena / Simrén, Magnus. ·Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden. ·Curr Gastroenterol Rep · Pubmed #23580243.

ABSTRACT: Gut microbiota alterations are increasingly being recognized as an important factor in the pathogenesis and pathophysiology of Irritable bowel syndrome (IBS). The onset of IBS symptoms after a bout of gastroenteritis comprises one of the strongest indications for the importance of gut microbiota for IBS. Moreover, recent studies have identified several susceptibility genes for IBS involved in the innate immunity and recognition of bacteria but also maintaining the integrity of the intestinal barrier. During recent years, it has also been demonstrated that IBS patients, or subgroups thereof, may have an altered microbiota composition relative to healthy individuals, mainly based on the analysis of fecal microbiota. Moreover, a positive effect of treatment with non-absorbable antibiotics and probiotics in IBS provides further indirect support for the relevance of gut microbiota alterations in IBS.

19 Review The microbiota link to irritable bowel syndrome: an emerging story. 2012

Jeffery, Ian B / Quigley, Eamonn M M / Öhman, Lena / Simrén, Magnus / O'Toole, Paul W. ·Department of Microbiology, University College Cork, Cork, Ireland. ·Gut Microbes · Pubmed #22895081.

ABSTRACT: Irritable Bowel Syndrome (IBS) is a clinically heterogeneous disorder which is likely to involve a number of causative factors. The contribution of altered intestinal microbiota composition or function to this disorder is controversial, and is the subject of much current research. Until recently, the technical limitations of the methodologies available have not permitted an adequate survey of low-abundance microbial species. Recent technological developments have enabled the analysis of the global population of the microbiome using high through-put, culture independent, 16S rRNA amplicon pyrosequencing. Using these new methodologies, we are able to gain important biological insights into the link between functional bowel disorders and the microbiome. This addendum contextualizes and summarizes the results of these studies, and defines the future challenges and opportunities in the field.

20 Review Meditation over medication for irritable bowel syndrome? On exercise and alternative treatments for irritable bowel syndrome. 2012

Asare, Fredrick / Störsrud, Stine / Simrén, Magnus. ·Department of Internal Medicine and clinical nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Sweden. fredrik.asare@gu.se ·Curr Gastroenterol Rep · Pubmed #22661301.

ABSTRACT: Complimentary alternative treatment regimens are widely used in irritable bowel syndrome (IBS), but the evidence supporting their use varies. For psychological treatment options, such as cognitive behavioral therapy, mindfulness, gut-directed hypnotherapy, and psychodynamic therapy, the evidence supporting their use in IBS patients is strong, but the availability limits their use in clinical practice. Dietary interventions are commonly included in the management of IBS patients, but these are primarily based on studies assessing physiological function in relation to dietary components, and to a lesser degree upon research examining the role of dietary components in the therapeutic management of IBS. Several probiotic products improve a range of symptoms in IBS patients. Physical activity is of benefit for health in general and recent data implicates its usefulness also for IBS patients. Acupuncture does not seem to have an effect beyond placebo in IBS. A beneficial effect of some herbal treatments has been reported.

21 Review Revisiting concepts of visceral nociception in irritable bowel syndrome. 2012

Keszthelyi, D / Troost, F J / Simrén, M / Ludidi, S / Kruimel, J W / Conchillo, J M / Masclee, A A. ·Top Institute Food and Nutrition, Wageningen, The Netherlands. daniel.keszthelyi@maastrichtuniversity.nl ·Eur J Pain · Pubmed #22504901.

ABSTRACT: BACKGROUND AND OBJECTIVE: Irritable bowel syndrome (IBS) is a common disorder characterized by abdominal pain related to defecation with a change in bowel habit. Patients with IBS often exhibit increased visceral sensitivity, which can be tested clinically by rectal balloon distension procedures. This paper aims to give an overview of mechanisms involved in visceral hypersensitivity in IBS by reviewing recent literature. DATABASES AND DATA TREATMENT: A literature search in the electronic databases Pubmed and MEDLINE was executed using the search terms 'visceral pain' or 'visceral nociception' or 'visceral hypersensitivity' and 'irritable bowel syndrome.' Both original articles and review articles were considered for data extraction. RESULTS: Recent advances in molecular neurophysiology provide knowledge to better understand the underlying mechanism in pain generation in the human gut, in particular, in IBS patients. Sensitization of peripheral nociceptive afferents, more specifically high-threshold afferents, has been proposed as one of the principle mechanism in the development of visceral hypersensitivity. On the other hand, central mechanisms also play an important role. In terms of clinical testing of visceral perception, considerable discrepancies remain, however, across different centres. CONCLUSION: Alterations in the modulatory balance of pro- and antinociceptive central processing of noxious peripheral input may serve as in integrative hypothesis for explaining visceral hypersensitivity in IBS. Nevertheless, it remains troublesome to estimate the contribution of central and peripheral factors in visceral hypersensitivity, posing a challenge in determining effective therapeutic entities.

22 Review Pathogenesis of IBS: role of inflammation, immunity and neuroimmune interactions. 2010

Ohman, Lena / Simrén, Magnus. ·Department of Internal Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, S-41345 Gothenburg, Sweden. ·Nat Rev Gastroenterol Hepatol · Pubmed #20101257.

ABSTRACT: IBS is one of the most common functional gastrointestinal disorders worldwide and is thought to be the result of disturbed neural function along the brain-gut axis. The mechanisms behind this disturbance are not clear, but important roles for low-grade inflammation and immunological alterations in the development of symptoms compatible with IBS have become evident. The development of long-standing gastrointestinal symptoms after infectious gastroenteritis and patients with IBD in remission frequently having functional gastrointestinal symptoms support this hypothesis. An increased innate immune activity in the intestinal mucosa and in blood is found in subpopulations of patients with IBS. Mast cells and monocytes seem to be particularly important. In addition, studies have demonstrated that IBS may be associated with an activated adaptive immune response. Increased epithelial barrier permeability and an abnormal gut flora might lead to increased activation of the intestinal immune system. Functional and anatomical evidence for abnormal neuroimmune interactions has been found in patients with IBS. The link between immune alterations and severity of gastrointestinal symptoms and the positive effect of anti-inflammatory treatments in IBS further highlight the relevance of neuroimmune interactions in this condition.

23 Review Peripheral factors in the pathophysiology of irritable bowel syndrome. 2009

Gunnarsson, J / Simrén, M. ·Department of Internal Medicine, Sahlgrenska University Hospital, Göteborg, Sweden. ·Dig Liver Dis · Pubmed #19665956.

ABSTRACT: The pathophysiology of IBS is complex and still incompletely known. Both central and peripheral factors are thought to contribute to the symptoms of IBS, including psychosocial factors, abnormal GI motility and secretion, and visceral hypersensitivity. In this review the involvement of peripheral factors in the pathophysiology in IBS is reviewed. Altered GI motility is commonly found in this patient group, even though a specific motor pattern has been hard to find. Colonic transit has been found to be of relevance for the bowel habit of the patient. Abnormal gas handling within the gut is also commonly seen, and seems to be one, but not the only factor responsive for bloating. There is also limited evidence supporting the presence of abnormal GI secretion in IBS, but its relevance for symptoms remains unclear. Visceral hypersensitivity is currently considered to be one of the most important pathophysiological factors in IBS. It can be modulated by several external and internal factors and recent studies support an association between colorectal sensitivity and the symptoms reported by the patients, especially pain.

24 Review Efficient diagnosis of suspected functional bowel disorders. 2008

Gunnarsson, Jenny / Simrén, Magnus. ·Department of Internal Medicine, Sahlgrenska University Hospital, Göteborg, Sweden. ·Nat Clin Pract Gastroenterol Hepatol · Pubmed #18679389.

ABSTRACT: Functional bowel disorders (FBDs) are common disorders that are characterized by various combinations of abdominal pain and/or discomfort, bloating and changes in bowel habits. At present, diagnosing FBDs often incurs considerable health-care costs, partly because unnecessary investigations are performed. Patients are currently diagnosed as having an FBD on the basis of a combination of typical symptoms, normal physical examination and the absence of alarm features indicative of an organic gastrointestinal disease. Basic laboratory investigations, such as a complete blood count, measurement of the erythrocyte sedimentation rate and serological tests for celiac disease, are useful in the initial evaluation. No further investigations are needed for most patients who have typical symptoms and no alarm symptoms. The most important alarm symptoms include signs of gastrointestinal bleeding, symptom onset above 50 years of age, a family history of colorectal cancer, documented weight loss and nocturnal symptoms. The presence of alarm symptoms obviously does not exclude an FBD, but further investigation is needed before confirmation of the diagnosis. For patients with predominant and severe diarrhea, a more thorough diagnostic work-up should normally be considered, including colonoscopy with colonic biopsies and a test for bile-acid malabsorption.

25 Clinical Trial Interaction between preprandial and postprandial rectal sensory and motor abnormalities in IBS. 2014

Törnblom, Hans / Van Oudenhove, Lukas / Tack, Jan / Simrén, Magnus. ·Department of Internal Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden University of Gothenburg Centre for Person-Centered Care (GPCC), Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. · Translational Research Center for Gastrointestinal Disorders (TARGID), University of Leuven, Leuven, Belgium. ·Gut · Pubmed #24142965.

ABSTRACT: BACKGROUND AND AIMS: Rectal sensory and motor interactions in patients with IBS have not been studied in detail. The aim of this study was to evaluate fasting and postprandial rectal sensorimotor characteristics and their interactions in IBS compared with healthy controls. DESIGN: We included 274 patients with IBS and 34 controls. All subjects underwent a rectal barostat study before and 60 min after a standardised liquid meal (800 kcal; 60% fat). Sensory thresholds, intensity of sensations, viscerosomatic referral and compliance were measured. During 15 min before the first distension sequence and until 50 min after meal intake, rectal balloon volumes were registered in 5 min intervals at operating pressure to quantify rectal tone. Mixed models were used to analyse the rectal tone response over time. RESULTS: Rectal sensory thresholds and compliance were decreased and viscerosomatic referral areas increased in patients with IBS compared with controls. Meal intake increased rectal sensitivity, compliance and referral areas in patients and controls and the same proportions of patients were hypersensitive to distension before and after meal intake. There was a higher basal rectal tone in IBS and a significantly different rectal tone response after meal intake in patients with IBS compared with controls and, interestingly, also in IBS with rectal hypersensitivity (defined in the preprandial state), compared with normosensitive patients. CONCLUSIONS: Meal intake affects rectal sensorimotor function in IBS and health. Importantly, the rectal tone responses to a high-caloric meal are different between patients with IBS and controls, as well as between hypersensitive and normosensitive patients with IBS.

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