Mechanism Of Irritable Bowel Syndrome Research Articles

Critical appraisal of the SIBO hypothesis and breath testing: A clinical practice update endorsed by the European society of neurogastroenterology and motility (ESNM) and the American neurogastroenterology and motility society (ANMS).

There is compelling evidence that microbe-host interactions in the intestinal tract underlie many human disorders, including disorders of gut-brain interactions (previously termed functional bowel disorders), such as irritable bowel syndrome (IBS). Small intestinal bacterial overgrowth (SIBO) has been recognized for over a century in patients with predisposing conditions causing intestinal stasis, such as surgical alteration of the small bowel or chronic diseases, including scleroderma and is associated with diarrhea and signs of malabsorption. Over 20 years ago, it was hypothesized that increased numbers of small intestine bacteria might also account for symptoms in the absence of malabsorption in IBS and related disorders. This SIBO-IBS hypothesis stimulated significant research and helped focus the profession's attention on the importance of microbe-host interactions as a potential pathophysiological mechanism in IBS. However, after two decades, this hypothesis remains unproven. Moreover, it has led to serious unintended consequences, namely the widespread use of unreliable and unvalidated breath tests as a diagnostic test for SIBO and a resultant injudicious use of antibiotics. In this review, we examine why the SIBO hypothesis remains unproven and, given the unintended consequences, discuss why it is time to reject this hypothesis and its reliance on breath testing. We also examine recent IBS studies of bacterial communities in the GI tract, their composition and functions, and their interactions with the host. While these studies provide important insights to guide future research, they highlight the need for further mechanistic studies of microbe-host interactions in IBS patients before we can understand their possible role in diagnosis and treatment of patient with IBS and related disorders.

Clinical efficacy of one-finger meditation massage on IBS-C based on the “gut-brain axis” theory: study protocol for a randomized controlled trial

BackgroundAs a common disorder of the gastrointestinal tract, irritable bowel syndrome (IBS) can have negative effects on patients and society, with irritable bowel syndrome with constipation(IBS-C) accounting for a large proportion of these effects. The main clinical manifestations of IBS-C are constipation, abdominal pain, and abdominal distension, which seriously impact the quality of life of patients. The mechanisms of IBS are complex, and the gut-brain axis has been an emerging and recognized theoretical system in recent years. Based on the theory of the gut-brain axis and the theory of Chinese medicine, we designed this study to evaluate the efficacy of one-finger meditation massage in treating IBS-C.Methods/designThis is a randomized controlled trial. Eligible patients with irritable bowel syndrome (IBS-C) wererandomized 1:1 to a test group (massage plus probiotics) and a control group (probiotics). Patients in the test group weretreated once every 10 days for three consecutive courses of treatment (i.e., three months) and weregiven Bifidobacterium trifolium capsules 630 mg/dose three times daily 30 min after meals every day during the treatment period, with follow-up observations at the end of the third and sixth months of the treatment period. The control group weregiven Bifidobacterium trifolium capsules 630 mg/dose, 3 times a day for 3 months, with follow-up observations at the end of the third and sixth months of the treatment period. The primary outcome indicators are the concentrations of 5-HT and substance P and the IBS Severity Scale (IBS-SSS) assessment. Secondary outcomes are the Bristol Rating Scale (BRSA) score, the IBS Quality of Life Questionnaire (IBS-QOL scale) score, and the assessment of the effectiveness of the evidence. The results wereassessed at the pretreatment, posttreatment, and follow-up stages. Any side effects weresubject to assessment.DiscussionThe aim of this trial is to provide a new method of treatment based on pharmacological treatment that is easy to use, easy to promote and has proven efficacy and to establish the efficacy and safety of treating IBS-C through this trial.Registration for TrialChinese Clinical Trial Registry ChiCTR2200066417 on 5 December 2022. https://www.chictr.org.cn/bin/project/edit?pid=183461

Evaluating the role of anxiety on the association between irritable bowel syndrome and brain volumes: a mediation analysis in the UK Biobank cohort.

There is a strong link between irritable bowel syndrome and brain volumes, yet, to date, research examining the mediators of this association has been little. Based on the phenotypic data of 15 248 participants from the UK Biobank, a two-stage mediation analysis was performed to assess the association among brain volumes, anxiety, and irritable bowel syndrome. In the first stage, we identified the candidate mediating role of anxiety for irritable bowel syndrome associated with brain volumes using regression models. Then, we quantified the magnitude of the mediation effects by evaluating the average causal-mediated effect and proportion of mediation through performing mediation analyses in the R package in the second stage. In the first stage, we identified the partly mediating role of anxiety in the association between irritable bowel syndrome and the volume of thalamus (P left = 1.16 × 10-4, P right = 2.41 × 10-4), and grey matter (P left = 3.22 × 10-2, P right = 1.18 × 10-2) in the VIIIa cerebellum. In the second stage, we observed that the proportion of the total effect of irritable bowel syndrome on volume of thalamus mediated by anxiety was 14.3% for the left region (β Average causal-mediated effect = -0.008, P Average causal-mediated effect = 0.004) and 14.6% for the right region (β Average causal-mediated effect = -0.007, P Average causal-mediated effect = 0.006). Anxiety mediated 30.8% for the left region (β Average causal-mediated effect = -0.013, P Average causal-mediated effect = 0.002) and 21.6% for the right region (β Average causal-mediated effect = -0.010, P Average causal-mediated effect x= 0.018) of the total effect of irritable bowel syndrome on the volume of grey matter in the VIIIa cerebellum. Our study revealed the indirect mediating role of anxiety in the association between irritable bowel syndrome and brain volumes, promoting our understanding of the functional mechanisms of irritable bowel syndrome and its related psychosocial factors.

The Prevalence of Irritable Bowel Syndrome after Severe Acute Respiratory Syndrome Coronavirus 2 Infection and Their Association: A Systematic Review and Meta-Analysis of Observational Studies

Investigate the prevalence of irritable bowel syndrome (IBS) after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and assess the association between IBS and SARS-CoV-2 infection. A systematic literature search for PubMed, Web of Science, Embase, Scopus, and the Cochrane Library was performed to identify all reports published before 31 December 2022. The confidence interval (CI), estimation effect (ES) of prevalence, and risk ratios (RR) were calculated to evaluate the prevalence of IBS after SARS-CoV-2 infection and their association. Individual results were pooled by the random-effects (RE) model. Subgroup analyses conducted a further investigation of the results. We employed funnel plots, Egger's test, and Begg's test to evaluate publication bias. Sensitivity analysis was performed for the assessment of the robustness of the result. The data on IBS prevalence after SARS-CoV-2 infection were extracted from two cross-sectional studies and ten longitudinal studies from nineteen countries with 3950 individuals. The IBS prevalence after SARS-CoV-2 infection ranges from 3% to 91% in different countries, and the overall pooled prevalence of IBS following SARS-CoV-2 infection is 15% (ES: 0.15; 95% CI, 0.11-0.20; p = 0.000). The data on the association between IBS and SARS-CoV-2 infection were extracted from six cohort studies from fifteen countries with 3595 individuals. The risk of IBS increased following SARS-CoV-2 infection but was not significant (RR: 1.82; 95% CI, 0.90-3.69; p = 0.096). In conclusion, the overall pooled prevalence of IBS following SARS-CoV-2 infection was 15%, and SARS-CoV-2 infection increased the overall risk of IBS but was not statistically significant. Further extra high-quality epidemiological evidence and studies to clarify the underlying mechanism of IBS following SARS-CoV-2 infection are needed.

Unrevealing of dysregulated hub genes linked with immune system and inflammatory signaling pathways in the pathogenesis of irritable bowel syndrome by system biology approaches

Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disorder characterized by abdominal pain and altered bowel movements. This disorder affects up to 10–23% of people globally and can affect both children and adults. Therefore, it is important to uncover early and novel therapeutic biomarkers and also reveal the pathobiology mechanisms of IBS. The main goal of this study is to investigate the hub genes and putative molecular mechanisms in IBS. Firstly, we identified 73 mutual differentially expressed genes (DEGs) from three RNA-seq databases. Then, functional gene annotation and pathway analysis of these common DEGs were enriched with interferon signaling, interferon gamma signaling, antigen processing-cross presentation, adaptive immune system, cytokine signaling in immune system, type II interferon signaling (IFNG), notch signaling pathway, MAPK signaling pathway, and IL-4 signaling pathway. In addition, a total number of 9 hub genes discovered as candidates of potential therapeutic biomarkers of IBS pathogenesis. Furthermore, transcription factors and regulatory protein kinases were identified as key signature molecules linked with IBS pathobiology. Taken together, this current study provided a novel understanding of biological mechanisms of IBS and may provide promising therapeutic targets.

ROLE OF HOMOCYSTEINE IN DEVELOPMENT OF ABDOMINAL PAIN IN PATIENTS WITH IRRITABLE BOWEL SYNDROME AND CONSTIPATION

Introduction. Irritable bowel syndrome with constipation poses a serious medical and social problem. Studying the pathogenetic mechanisms of irritable bowel syndrome with constipation may improve therapeutic approaches and patient’s quality of life.
 The aim of this study is to investigate the homocysteine role in the development of abdominal pain syndrome in patients with irritable bowel syndrome and constipation, taking into account body mass index.
 Subjects and methods. The study involved 55 patients with functional bowel disorders, who were divided into 2 groups: group I (n=27) included patients with functional constipation; II group (n=28) involved patients with irritable bowel syndrome and constipation. The average age of patients in group I was 35.7±8.63 years, in group II – 34.50±9.06 years, the ratio of men and women was 7(25.9%) / 20(74.1%) and 10 (35.7%) / 18(64.28%), respectively. A modified faces pain scale was used to assess pain intensity. Height, weight, and waist circumference were measured, body mass index was calculated according to formula: body mass index = weight (kg)/height (m2). The homocysteine level in the blood serum was measured.
 Results. Abdominal obesity with the waist circumference greater than 88 cm for women and greater than 102 cm for men was recorded in 6 (21.42%) patients with irritable bowel syndrome and constipation and in 4 (14.81%) patients with functional constipation. The severity of pain and meteorism according to the modified faces scale in patients with irritable bowel syndrome with constipation were respectively 2.4 and 1.7-fold (р˂0.0001) higher than the respective parameters in the patients with functional constipation.
 The content of homocysteine in the blood serum in the patients with irritable bowel syndrome and constipation was 1.9-fold (р˂0.0001) higher than in the patients with functional constipation. Increased homocysteine level led to the increase in the risk of developing irritable bowel syndrome and constipation (RR=3.61; 95%CI 1.37–9.52; p<0.01). It is important to stress that the serum homocysteine level in the patients with irritable bowel syndrome with constipation was directly correlated with the pain severity assessed by the modified faces pain scale (r=+0.9; p=0.0001).
 Conclusion. The severity of abdominal pain and meteorism in patients with irritable bowel syndrome and constipation is associated with the homocysteine level in the blood serum.

Type of Rectal Barostat Protocol Affects Classification of Hypersensitivity and Prediction of Symptom Severity in Irritable Bowel Syndrome.

Background/AimsVisceral hypersensitivity is an important pathophysiologic mechanism in irritable bowel syndrome (IBS). We compared 2 barostat distension protocols and their ability to distinguish between IBS patients and healthy controls, identify subjects with rectal hypersensitivity, and their associations with gastrointestinal symptom severity.MethodsWe retrospectively reviewed all patients at our unit that had undergone barostat investigations 2002-2014. Protocol 1 (n = 369) used phasic isobaric distensions with stepwise increments in pressure and protocol 2 (n = 153) used pressure controlled ramp inflations. Both protocols terminated when subjects reported pain or maximum pressure was reached. Thresholds for first sensation, urgency, discomfort and pain were established. Age- and gender-matched controls were used for comparison. The gastrointestinal symptom rating scale–IBS, and the hospital anxiety and depression scale were used for symptom reports.ResultsA significantly higher proportion of patients was classified as having hypersensitivity in protocol 1 vs protocol 2 for all thresholds (P < 0.001). Patients with visceral hypersensitivity, defined based on rectal pain thresholds in protocol 1 had more severe gastrointestinal symptoms overall as well as anxiety, whereas these associations were weaker or in most cases absent when visceral hypersensitivity was defined based on rectal pain thresholds in protocol 2.ConclusionOur study indicates that a rectal barostat protocol using phasic isobaric distensions with stepwise pressure increments is more sensitive in IBS patients with respect to identifying subjects with rectal hypersensitivity and a link with IBS symptoms.

Comparison of Geqingpi and Sihuaqingpi based on ultra-high-performance liquid chromatography-tandem mass spectrometry combined with multivariate statistics, network pharmacology analysis, and molecular docking.

Citri Reticulatae Pericarpium Viride is used in traditional Chinese medicine as Geqingpi and Sihuaqingpi varieties. We used the ultra-high-performance liquid chromatography-quadrupole-Exactive Orbitrap-mass spectrometry method and high-performance liquid chromatography-triple quadrupole-tandem mass spectrometry to analyze the chemical compounds in these varieties. Principal components analysis and orthogonal partial least squares discriminant analysis were used to analyze the quantitative results. Network pharmacology and molecular docking technology were used to forecast Citri Reticulatae Pericarpium Viride treatment mechanisms in irritable bowel syndrome. We identified 44 main compounds in Citri Reticulatae Pericarpium Viride. Compared to Sihuaqingpi, Geqingpi had higher narirutin, didymin, naringenin, and hesperetin, and lower hesperidin, isosinensetin, nobiletin, 3,5,6,7,8,3',4'-hexamethoxyflavone, tangeretin. Tangeretin, nobiletin, narirutin, didymin, and isosinensetin were the main compounds distinguishing Geqingpi from Sihuaqingpi. We found that the MAPK signaling pathway, which is closely related to irritable bowel syndrome, was an important target pathway. TP53, HRAS, MAPK1, AKT1, and EGFR were important targets in this pathway. Eriodictyol-7-O-rutinoside, narirutin, limonin, and hesperidin showed a good binding ability to the five targets. Orientin, unique to Sihuaqingpi, bound well to TP53, MAPK1, AKT1, and EGFR, while rhoifolin bound well to TP53, HRAS, MAPK1, AKT1, and EGFR. Hesperetin, unique to Geqingpi, bound well to TP53, HRAS, and MAPK1, while naringenin bound well to HRAS. Hesperidin and didymin bound well to TP53, MAPK1, AKT1, and EGFR.

Proteomic analysis of rat colonic mucosa following acupuncture treatment for irritable bowel syndrome with diarrhea

To investigate the molecular pathological mechanisms of irritable bowel syndrome with diarrhea (IBS-D) and elucidate the effects of acupuncture on IBS-D colonic mucosa protein abundance in rats, a label-free high-throughput liquid chromatography-tandem mass spectrometry (LC-MS)-based proteomics analysis was used to survey the global changes of colonic mucosa proteins between different groups. Sixteen Sprague-Dawley (SD) male rats were randomly divided into four groups: the control group (C); the IBS-D model group (M); the syndrome differentiation acupuncture group (SD) and the traditional acupuncture group (T). IBS-D model rats were obtained using the CAS (chronic acute combining stress model) method. Comparative bioinformatics analysis of the proteomic data was analyzed using MaxQuant software, Perseus software, online tools DAVID, VENNY and STRING. Functional enrichment and network analyses revealed a close relationship between IBS-D and several biological processes including energy metabolism, muscular excitation/contraction, and both traditional acupuncture and syndrome differentiation acupuncture can reverse the impairments of normal energy metabolism. Moreover, the syndrome differentiation acupuncture can regulate the protein cluster relating inflammation, wound repair and cell protection against oxidative stress which is associated with acupuncture analgesic effect. Differentially expressed proteins Atp5a1 and Bpnt1 were selected as representative proteins and subjected to western blotting. In conclusion, our study provides further insight into the pathological and molecular mechanisms of IBS-D and acupuncture treatments, and serves as an experimental basis for clinical applications.

Upregulation of Netrin-1 in the hippocampus mediates the formation of visceral hypersensitivity induced by maternal separation

Early adverse life events (EALs), such as maternal separation (MS), can cause visceral hypersensitivity, which is thought to be a key pathophysiological mechanism of irritable bowel syndrome (IBS). Previous studies mainly focused on EALs-induced visceral hypersensitivity in adulthood but did not consider that it may have occurred in the preadult period. We previously found that rats who experienced MS suffered from visceral hypersensitivity starting from the post-weaning period. Moreover, the hippocampus is considered to be critical in regulating the formation of visceral hypersensitivity induced by MS. But the underlying mechanisms throughout different life periods are unclear. In this study, behavioral tests, RNA-seq, lentiviral interference, and molecular biology techniques were applied to investigate the molecular mechanism in the hippocampus underlying MS-induced long-lasting visceral hypersensitivity. It was found that both visceral sensitivity and anxiety-like behaviors were significantly increased in MS rats in post-weaning, prepubertal, and adult periods, especially in the prepubertal period. Subsequently, RNA-seq targeting the hippocampus identified that the expression level of Netrin-1 was significantly increased in all periods, which was further confirmed by quantitative real-time PCR and Western blot. Knocking-down hippocampal Netrin-1 in the post-weaning period by lentivirus interference alleviated visceral hypersensitivity and anxiety-like behaviors of MS rats in the later phase of life. In addition, deleted in colorectal cancer (DCC), instead of neogenin-1(Neo-1) or uncoordinated (UNC5), was proved to be the specific functional receptor of Netrin-1 in regulating visceral hypersensitivity, whose upregulation may result in the most severe symptoms in the prepubertal period. Furthermore, the activation of the Netrin-1/DCC pathway could enhance long-term potentiation (LTP) in the hippocampus, probably via recruitment of the AMPA receptor subunit GluA1, which finally resulted in the formation of visceral hypersensitivity. These novel findings suggest that long-lasting over-expression of Netrin-1 can mediate visceral hypersensitivity and anxiety disorder from the post-weaning period to adulthood by activating DCC/GluA1 pathway in the hippocampus. Moreover, early intervention of Netrin-1 in the post-weaning period could lead to significant symptom relief afterward, which provides evidence that the Netrin-1/DCC/GluA1 signaling pathway may be a potential therapeutic target for the treatment of visceral hypersensitivity in clinics.

Transcutaneous Electrical Acustimulation Improves Irritable Bowel Syndrome With Constipation by Accelerating Colon Transit and Reducing Rectal Sensation Using Autonomic Mechanisms.

Slow colon transit and visceral hypersensitivity are recognized as major pathophysiological mechanisms in irritable bowel syndrome with constipation (IBS-C). However, there is a lack of therapies targeting both abdominal pain and colonic motility. This study was designed to investigate the long-term effects and possible mechanisms of transcutaneous electrical acustimulation (TEA) in patients with IBS-C. Fifty-two patients with IBS-C were randomized into 2 groups: daily TEA for 4 weeks (n = 26) and daily sham-TEA for 4 weeks (n = 26). The number of complete spontaneous bowel movements per week (CSBMs/week, primary outcome), Irritable Bowel Syndrome Severity Scoring System, Patient Assessment of Constipation Quality of Life, visual analog scale (VAS) pain score, colonic transit time, and anorectal physiology were evaluated before treatment and at the end of the treatment. Colonic transit was assessed with radiopaque markers. Electrocardiograms were recorded for assessing autonomic functions. (i) TEA improved constipation and abdominal pain. After the treatment, the number of CSBMs/week during the last week in the TEA group was higher than that in the sham-TEA group (3.5 ± 1.6 vs 2.3 ± 0.6, P = 0.002). Similar effects were also noted in the visual analog scale pain score ( P = 0.002) and Irritable Bowel Syndrome Severity Scoring System score ( P = 0.025). In addition, there was a significant improvement in the quality of life of patients with constipation. The Patient Assessment of Constipation Quality of Life total score was significantly decreased in the TEA group ( P = 0.004). (ii) Compared with sham-TEA, TEA improved colon transit ( P = 0.002) and increased the threshold of rectal sensation (desire to defecate, P = 0.004; maximum tolerability, P &lt; 0.001). (iii) TEA increased vagal activity, compared with sham-TEA ( P &lt; 0.05); at the end of the treatment, the vagal activity was significantly correlated with colon transit and the CSBMs/week. TEA improves constipation and symptoms of IBS by accelerating colon transit and reducing rectal sensation, possibly mediated by using the autonomic mechanisms.

Mechanism of the Treatment of Irritable Bowel Syndrome with Sini Powder and Tong Xie Yao Fang Decoction Based on Network Pharmacology

This study used a network pharmacology approach to investigate the potential active ingredients of Sini Powder and Tong xie yao fang decoction and the underlying mechanisms in irritable bowel syndrome (IBS) treatment. The potential active ingredients of Sini Powder and Tong xie yao fang decoction were obtained from TCMSP databases, and the potential targets of the active ingredients were predicted and analyzed by using the Swiss Target Prediction database. T Genecard, DisGeNET, and OMIM databases were processed to screen the potential therapeutic targets in IBS. The interaction of overlapped candidates between the potential biotarget of herb extracts and the potential therapeutic target of IBS were analyzed by STRING website and visualized by the Cytoscape V3.8.0 software. Gene ontology (GO) analysis and Kyoto Genomics and Genomics Encyclopedia (KEGG) pathway were processed to categorize and map the potential biofunctions and effects of these candidates by using David database. Result. There were 139 predicted active components and 248 related biotargets of Sini Powder and Tong xie yao fang decoction which were involved in IBS treatment, and 522 annotations and 101 related pathways are obtained by enrichment analysis (P < 0.01, FDR < 0.05). The underlying mechanisms of Sini Powder and Tong xie yao fang decoction may be related to neuroactive ligand-receptor interaction, calcium, cAMP, and HIF-1 signaling pathways. In conclusion, our results showed that the effect and mechanism of Sini Powder and Tong xie yao fang decoction in IBS treatment were in multi-ingredient, multitargets and multipathways, which would provide several potential and promising strategies for the further research and development of Sini Powder and Tong xie yao fang decoction on IBS treatment.

Searching for a Definition of Refractory Irritable Bowel Syndrome: a Systematic Review and Meta-analysis.

The pathological mechanism of irritable bowel syndrome (IBS) is unclarified, which commonly leads to unresponsiveness to conventional treatments. The diagnostic criteria for refractory IBS are not clearly defined. We performed a systematic review to summarize the key points of the definition of refractory IBS in different studies. We also conducted a meta-analysis to explore whether the diverse definitions for refractory IBS affect the therapeutic effect of gut-directed hypnotherapy (GDH). We searched OVID Medline, Embase and Cochrane (until September 2020) for randomized controlled trials (RCTs) recruiting patients with refractory IBS. We evaluated the definition of refractory IBS through the following aspects: duration of symptoms, unresponsive to dietary intervention, lifestyle modification, pharmacology, psychology, severity assessment and adequate explanation. The effect of the different definitions for refractory IBS on the therapeutic effect of gut-directed hypnotherapy (GDH) was checked by a meta-analysis. Twenty-one RCTs were finally included. Six (28.6%) out of 21 RCTs recruited patients with symptoms lasting for over 12 months; 8 (38.1%) RCTs reported a prior use of dietary intervention; 1 (4.8%) RCT reported the use of lifestyle modification; 11 (52.4%) RCTs recruited patients who were unresponsive to pharmacology; 2 (9.5%) RCTs recruited patients with no response to psychological therapy ; 5 (23.8%) RCTs had symptoms severity assessment; and 8 (38.1%) RCTs recruited patients who were informed adequately. Despite being tested in trials with heterogeneous definition of refractory IBS, GDH had similar effectiveness when compared with supportive treatment [standardized mean difference (SMD)=-0.69, 95%CI: -0.93 to -0.44)] or waiting-list control (SMD=-0.54, 95%CI: -0.98 to -0.10). Varied definitions in refractory IBS were common phenomena in clinical studies. Resistance to symptom severity assessment and psychological treatments should be more explicitly defined. Gut-directed hypnotherapy was efficacious for refractory IBS and was not affected by the diversity in the definition of refractory IBS among RCTs.

Microinflammation in the intestinal mucosa and symptoms of irritable bowel syndrome.

Potential etiological mechanisms of irritable bowel syndrome (IBS) have been reported, and emerging data suggest that immune activation is present in a major subset of IBS, especially in those with diarrhea. Intestinal mucosal mast cell and intraepithelial lymphocyte (IEL) infiltration and related factors were examined in patients with IBS. In addition, the correlations of symptoms and micro-inflammation were assessed. Intestinal biopsy specimens were obtained from patients with IBS and controls. Mast cells and IELs were stained with specific antibodies. The mRNA levels of cytokines and chemokines were assessed by quantitative reverse transcription polymerase chain reaction. Infiltration of mast cells in the duodenum was significantly higher in IBS patients than in control subjects. The infiltration of IELs was higher in the duodenum and terminal ileum of IBS patients compared to the control subjects. The numbers of duodenal and ileal IELs were significantly correlated. The number of IELs but not mast cells in the duodenum and terminal ileum was significantly correlated with diarrhea frequency in control subjects and IBS patients. The expression level of the chemotactic chemokine CXCL11 was significantly higher in the duodenum of IBS patients. Duodenal mast cells and IELs were increased in IBS patients. In addition, a positive correlation was found between the number of duodenal and ileal IELs and the frequency of diarrhea. Given that the present study was strictly observational, further studies are needed to clarify the pathophysiological functions associated with micro-inflammation in IBS.

GWAS of stool frequency provides insights into gastrointestinal motility and irritable bowel syndrome

SummaryGut dysmotility is associated with constipation, diarrhea, and functional gastrointestinal disorders like irritable bowel syndrome (IBS), although its molecular underpinnings are poorly characterized. We studied stool frequency (defined by the number of bowel movements per day, based on questionnaire data) as a proxy for gut motility in a GWAS meta-analysis including 167,875 individuals from UK Biobank and four smaller population-based cohorts. We identify 14 loci associated with stool frequency (p ≤ 5.0 × 10−8). Gene set and pathway analyses detected enrichment for genes involved in neurotransmitter/neuropeptide signaling and preferentially expressed in enteric motor neurons controlling peristalsis. PheWAS identified pleiotropic associations with dysmotility syndromes and the response to their pharmacological treatment. The genetic architecture of stool frequency correlates with that of IBS, and UK Biobank participants from the top 1% of stool frequency polygenic score distribution were associated with 5× higher risk of IBS with diarrhea. These findings pave the way for the identification of actionable pathological mechanisms in IBS and the dysmotility syndromes.

Tratamiento del síndrome de intestino irritable por gastroenterólogos: resultados de un estudio de corte transversal a partir de una encuesta elaborada por expertos

Introduction. Irritable bowel syndrome (IBS) accounts for a significant deterioration in the quality of life of patients who suffer from it and is a common reason for consultation in gastroenterology. The treatment of this syndrome includes a wide variety of medications and recommendations based on different factors of its physiopathology. However, the results are usually variable and sometimes unsatisfactory for either the patient or the treating physician. The main objective of the present work is to describe the different treatments used by gastroenterologists in the management of IBS in Argentina. Materials and methods. Questionnaire of forty-seven questions, prepared by experts, distributed by medical associations of gastroenterology in Argentina and answered by specialists via Google Forms. Results. 304 responses, 157 from women (51.6%) and 147 from men (48.4%). The mean age was 44 and 49.9 years, respectively. 87.5% consider improvement of quality of life as the main goal of treatment. Regarding physiopathology of diarrhea variant irritable bowel syndrome (IBS-D), 49.5% considered emotional stress, while for constipation variant irritable bowel syndrome (IBS-C), 42.8% considered it multifactorial, with a predominance of slow colonic transit. No treatment option was rated as very effective by more than 50% of the respondents. Rifaximin was considered the most effective treatment in IBS-D, while polyethylene glycol was for IBS-C. Statistical significant differences were observed among gastroenterology subspecialties in the treatment of IBS-D with respect to the efficacy of diet, amitriptyline and antibiotics other than rifaximin, and regarding the effectiveness for bisacodyl/picosulfate and antibiotics in the treatment of IBS-C. Conclusion. The most common pathophysiological mechanism in IBS-D is stress. The vast majority of respondents consider that the main goal of treatment is the improvement of the quality of life, over symptomatic relief. None of the drugs is considered very effective in the treatment of the different IBS variants by at least 50% of those surveyed. Statistically significant differences were observed in the proportion of monthly consultations for IBS regarding to age and in the effectiveness considered for some treatments in relation to the subspecialty of physicians. The therapeutic approach to IBS by Argentine gastroenterologists is varied and somewhat heterogeneous, resulting in a still inappropriate management of this condition.

A putative anti-inflammatory role for TRPM8 in irritable bowel syndrome-An exploratory study.

Chronic and recurring pain is a characteristic symptom in irritable bowel syndrome (IBS). Altered signaling between immune cells and sensory neurons within the gut may promote generation of pain symptoms. As transient receptor potential melastatin 8 (TRPM8) agonists, such as L-menthol in peppermint oil, have shown to attenuate IBS pain symptoms, we began investigating potential molecular mechanisms. Colonic biopsy tissues were collected from patients with IBS and controls, in two separate cohorts. Immunohistochemistry was performed to identify TRPM8 localization. Quantitative PCR was performed to measure mucosal mRNA levels of TRPM8. In addition, functional experiments with the TRPM8 agonist icilin were performed ex vivo to examine cytokine release from biopsies. Daily diaries were collected to ascertain pain symptoms. In biopsy tissue from IBS patients, we showed that TRPM8 immunoreactivity is colocalized with immune cells predominantly of the dendritic cell lineage, in close approximation to nerve endings, and TRPM8 protein and mRNA expression was increased in IBS patients compared to controls (p<0.001). TRPM8 mRNA expression showed a significant positive association with abdominal pain scores (p=0.015). Treatment of IBS patient biopsies with icilin reduced release of inflammatory cytokines IL-1β, IL-6, and TNF-α (p<0.05). These data indicate TRPM8 may have important anti-inflammatory properties and by this virtue can impact neuro-immune disease mechanisms in IBS.

Irritable Bowel and Bacterial Overgrowth Syndromes: a Bacterial Link Hypothesis of Functional Disease

Aim. Assessment of the irritable bowel syndrome (IBS) and small intestinal bacterial overgrowth syndrome (SIBO) interlinkage.Key points. SIBO may represent a "peripheral" mechanism of IBS, aside to nonspecific inflammation, increased epithelial permeability and local immune system activation. In various assays, the SIBO rate in IBS patients was 4-46% vs. 0-13% in an intact cohort. A limited diagnosability of SIBO obscures the SIBO-IBS causal interplay. Impaired motility in IBS may predispose to the SIBO development. Proinflammatory cytokines and mediators in SIBO, in turn, provoke visceral hypersensitivity and intense motility, the key IBS factors. Both conditions relate to qualitative and quantitative changes in microbiota, which warrants the application of probiotic Lactobacillus and Bifidobacterium strains.Conclusion. Further research into the SIBO-IBS interface is required for developing optimal probiotic-based therapies.

Cytokines in the colon, central nervous system and serum of irritable bowel syndrome rats

ObjectiveThe aim of this study was to detect the expression of interleukin (IL)-1β and transforming growth factor (TGF)-β1 in the colonic tissue and serum of irritable bowel syndrome (IBS) rats, as well as the distribution and expression of corticotropin-releasing factor (CRF) in the spinal cord and brain of the visceral hypersensitivity rats, thus to ascertain the mechanism of visceral hypersensitivity signal conduction pathway.MethodsThe expression of IL-1β and TGF-β1 in the colonic tissue and serum of IBS rats was screened by the liquid chip technology and verified by RT-PCR technology. Then the quantitative analysis of CRF in the spinal cord and brain was achieved by the immunohistochemical method and computerized image system.ResultThe rat model with visceral hypersensitivity was successfully established. Among the screened indicators of IL-1β and TGF-β1 in colon tissue and serum, only the expression of IL-1β in the model group was up-regulated (P < 0.05). The immunohistochemical method showed that CRF was expressed in the spinal cord, hypothalamus, and the third ventricle. The positive index number of the model groups was higher than that of the control group (P < 0.01).ConclusionFrom the research, it can be inferred that IL-1β may participate in the pathogenesis mechanism of IBS via regulating the colon function. The increasing expression of CRF linked to stress in the spinal cord, hypothalamus and the third ventricle indicated that it might play an important role in the mechanisms of visceral hypersensitivity signal conduction pathway.

Association of Peroxiredoxin 1 and brain-derived neurotrophic factor serum levels with depression and anxiety symptoms in patients with irritable bowel syndrome

BackgroundOxidative stress is considered a possible mechanism of irritable bowel syndrome (IBS) and depression. This study determined the possible association of serum peroxiredoxin 1 (PRDX1; a key antioxidant enzyme) and brain-derived neurotrophic factor (BDNF) with anxiety and depression symptoms in IBS patients. MethodsAccording to the Rome IV diagnostic criteria, 177 IBS patients from February 2019 to July 2019 were included. Serum levels of PRDX1, BDNF, and TNFα were detected by enzyme-linked immunosorbent assay. Levels of anxiety and depression were assessed with the Self-rating Anxiety Scale (SAS) and Self-rating Depression Scale (SDS). ResultsCompared with normal IBS patients, patients with anxiety and depression symptoms had significantly higher serum PRDX1 (p<0.001; p=0.002) and TNFα (p<0.001; p = 0.002) and significantly lower BDNF (p < 0.001; p = 0.002). Serum PRDX1 (r = 0.659, p < 0.001; r = 0.466, p < 0.001) and TNFα (r = 0.531, p < 0.001; r = 0.449, p < 0.001) were positively correlated with SAS and SDS, respectively, whereas BDNF was negatively correlated with SAS (r = 0.594, p < 0.001) and SDS (r = 0.534, p < 0.001). Multivariable regression analysis revealed that IBS severity, BDNF, and PRDX1 were significant predictors of anxiety. BDNF was also a significant predictor of depression. ConclusionElevated PRDX1 and decreased BDNF in serum may be closely related to psychological symptoms in IBS. Results of this study suggested that PRDX1 may be an important target for IBS treatment in fighting against intestinal and psychological symptoms.