Inflammation as a basis for functional GI disorders

Mast cell modulation: A novel therapeutic strategy for abdominal pain in irritable bowel syndrome

Irritable bowel syndrome (IBS) is one of the most prevalent gastrointestinal disorders characterized by recurrent abdominal pain and an altered defecation pattern. Chronic abdominal pain represents the hallmark IBS symptom and is reported to have the most bothersome impact on the patient's quality of life. Unfortunately, effective therapeutic strategies reducing abdominal pain are lacking, mainly attributed to a limited understanding of the contributing mechanisms. In the past few years, exciting new insights have pointed out that altered communication between gut immune cells and pain-sensing nerves acts as a hallmark driver of IBS-related abdominal pain. In this review, we aim to summarize our current knowledge on altered neuro-immune crosstalk as the main driver of altered pain signaling, with a specific focus on altered mast cell functioning herein, and highlight the relevance of targeting mast cell-mediated mechanisms as a novel therapeutic strategy for chronic abdominal pain in IBS patients.

Predictors of pelvic pain in a general urology clinic population

Objectives

To assess the prevalence and predictors of chronic pelvic pain in a general urology population presenting for evaluation of unrelated non-painful complaints.Generalized pelvic pain is estimated to afflict between 6% and 26% of women and is often multifactorial in aetiology. A paucity of prospective research exists to characterize chronic pelvic pain patterns and to understand related predictors.

Materials and Methods

This is a prospective, cross-sectional survey-based study of female patients presenting to a general urology clinic over a 10-month period (7/2018-5/2019). Patients completed a 32-item survey with questions pertaining to demographics, comorbidities and chronic pelvic pain characteristics. Comparison tests (chi-squared, Fisher's exact) and stepwise multivariable logistic modelling were performed to assess for predictors of chronic pelvic pain.

Results

A total of 181 women completed the survey, with a mean age of 56 years. Overall, 75 (41%) women reported chronic pelvic pain. Those with chronic pelvic pain were younger compared to those without (52 vs 59 years, p = 0.001). Univariable logistic regression analysis identified BMI, depression, fibromyalgia, overactive bladder and any bowel symptoms as possible positive predictors of chronic pelvic pain. Final best-fit multivariable model found overactive bladder, fibromyalgia and presence of bowel symptoms as independent positive predictors of chronic pelvic pain.

Conclusions

Our study is one of the few studies that has prospectively analysed chronic pelvic pain and its predictors. The present study identified significant associations with overactive bladder, fibromyalgia and bowel symptoms. Further research is needed to better understand the aetiologies of chronic pelvic pain and the possible relationship with identified clinical predictors.

Modulating the gut microenvironment as a treatment strategy for irritable bowel syndrome: a narrative review

Irritable bowel syndrome (IBS) is a disorder of gut-brain interaction with a complex pathophysiology. Growing evidence suggests that alterations of the gut microenvironment, including microbiota composition and function, may be involved in symptom generation. Therefore, attempts to modulate the gut microenvironment have provided promising results as an indirect approach for IBS management. Antibiotics, probiotics, prebiotics, food and faecal microbiota transplantation are the main strategies for alleviating IBS symptom severity by modulating gut microbiota composition and function (eg. metabolism), gut barrier integrity and immune activity, although with varying efficacy. In this narrative review, we aim to provide an overview of the current approaches targeting the gut microenvironment in order to indirectly manage IBS symptoms.

Gut Microbiota Manipulation in Irritable Bowel Syndrome

Increased knowledge suggests that disturbed gut microbiota, termed dysbiosis, might promote the development of irritable bowel syndrome (IBS) symptoms. Accordingly, gut microbiota manipulation has evolved in the last decade as a novel treatment strategy in order to improve IBS symptoms. In using different approaches, dietary management stands first in line, including dietary fiber supplements, prebiotics, and probiotics that are shown to change the composition of gut microbiota, fecal short-chain fatty acids and enteroendocrine cells densities and improve IBS symptoms. However, the exact mixture of beneficial bacteria for each individual remains to be identified. Prescribing nonabsorbable antibiotics still needs confirmation, although using rifaximin has been approved for diarrhea-predominant IBS. Fecal microbiota transplantation (FMT) has recently gained a lot of attention, and five out of seven placebo-controlled trials investigating FMT in IBS obtain promising results regarding symptom reduction and gut microbiota manipulation. However, more data, including larger cohorts and studying long-term effects, are needed before FMT can be regarded as a treatment for IBS in clinical practice.

Pathophysiology of Gastroparesis Syndromes Includes Anatomic and Physiologic Abnormalities

BACKGROUND

Factors underlying gastroparesis are not well defined.

AIMS

We hypothesized that multiple systems may be involved in patients with gastroparesis symptoms and performed a comparative physiologic study.

METHODS

We studied 43 consecutive eligible patients with gastroparetic symptoms categorized by GI symptoms, metabolic status, illness quantification, and gastric physiology. Patients were evaluated by two methods in each of five core areas: inflammatory, autonomic, enteric, electrophysiologic, and hormonal with abnormalities examined by correlations.

RESULTS

Patients had similar GI symptoms regardless of baseline gastric emptying or diabetic/idiopathic status, and all patients demonstrated abnormalities in each of the 5 areas studied. Nearly all patients presented with elevated markers of serum TNFα (88%) and serum IL-6 (91%); elevated cutaneous electrogastrogram frequency (95%); and interstitial cells of Cajal count abnormalities (inner: 97%, outer: 100%). Measures of inflammation correlated with a number of autonomic, enteric anatomy, electrophysiologic and hormonal abnormalities.

CONCLUSIONS

We conclude that patients with the symptoms of gastroparesis have multiple abnormalities, when studied by traditional, as well as newer, diagnostic assessments. Inflammation appears to be a fundamental abnormality that affects other organ systems in symptomatic patients. Future work on gastroparetic syndromes and their treatment may benefit from a focus on the diffuse nature of their illness, diverse pathophysiologic mechanisms involved, especially the possible causes of underlying inflammation and disordered hormonal status.

TRAIL REGISTRY

This study is registered with Clinicaltrials.gov under study # NCT03178370 https://clinicaltrials.gov/ct2/show/NCT03178370 .

Effects of heat stress on the gut health of poultry

Stress is a biological adaptive response to restore homeostasis, and occurs in every animal production system, due to the multitude of stressors present in every farm. Heat stress is one of the most common environmental challenges to poultry worldwide. It has been extensively demonstrated that heat stress negatively impacts the health, welfare, and productivity of broilers and laying hens. However, basic mechanisms associated with the reported effects of heat stress are still not fully understood. The adaptive response of poultry to a heat stress situation is complex and intricate in nature, and it includes effects on the intestinal tract. This review offers an objective overview of the scientific evidence available on the effects of the heat stress response on different facets of the intestinal tract of poultry, including its physiology, integrity, immunology, and microbiota. Although a lot of knowledge has been generated, many gaps persist. The development of standardized models is crucial to be able to better compare and extrapolate results. By better understanding how the intestinal tract is affected in birds subjected to heat stress conditions, more targeted interventions can be developed and applied.

Upper Gastrointestinal Sensitization And Symptom Generation

Functional gastrointestinal disorders (FGIDs) are a highly prevalent group of heterogeneous disorders, and their diagnostic criteria are symptom-based, with the absence of anatomical and biochemical abnormalities of the gastrointestinal tract. Chronic visceral symptoms are common both in patients with an identifiable organic disease but also in FGID patients. Patients suffering from upper gastrointestinal functional disorders typically present with various symptoms such as early satiety, postprandial fullness, bloating, nausea, vomiting, and epigastric pain. Considering their increasing prevalence, difficulties in diagnosis, and low quality of life, FGIDs have become an emerging problem in gastroenterology. We aimed to provide an updated summary of pathways involved in visceral sensitization. We examined the recent literature searching for evidence of the most important studies about the mechanisms underlying gastrointestinal symptom generation and sensitization.

Abnormal Uroguanylin Immunoreactive Cells Density in the Duodenum of Patients with Diarrhea-Predominant Irritable Bowel Syndrome Changes following Fecal Microbiota Transplantation

Altered densities of enteroendocrine cells play an important role in patients with irritable bowel syndrome (IBS). Uroguanylin activates guanylate cyclase-C to regulate intestinal electrolyte and water transport. Aim. To quantify uroguanylin immunoreactive cells density in the duodenum of diarrhea-predominant IBS (IBS-D) patients compared to controls and to investigate the effect of fecal microbiota transplantation (FMT) on these cell densities. Method. Twelve patients with IBS-D according to Rome III criteria were included. The cause was identified as post infectious (PI, n = 6) or idiopathic (n = 6). They completed the IBS-symptom questionnaire before and 3 weeks after FMT. Thirty grams of fresh feces donated from healthy relatives were diluted with 60 ml normal saline and instilled via endoscope into the duodenum. Biopsies were taken from the patients' duodenum before and 3 weeks after FMT. Duodenal biopsies taken from eight healthy controls were also included. The biopsies were immunostained for uroguanylin and quantified using computerized image analysis. Results. Uroguanylin immunoreactive cells were found both in duodenal villi and crypts in both controls and IBS-D patients. The densities of uroguanylin immunoreactive cells were significantly lower in the villi (P < 0.0001) and higher in the crypts (P < 0.0001) for the patients than the controls. Following FMT, the densities of uroguanylin immunoreactive cells for the total group and idiopathic subgroup decreased significantly in the duodenal crypts (P = 0.049 and 0.04, respectively) but not in the villi. No significant changes were shown in the PI-IBS subgroups. The cells density in only the crypts correlated with diarrhea (r = 0.97, P = 0.001) and bloating (r = -0.91, P = 0.01) in the PI-IBS subgroup before FMT and with abdominal pain (r = 0.63, P = 0.03) in the total group of IBS-D patients after FMT. Conclusion. Altered uroguanylin immunoreactive cells density was found in IBS-D patients compared to controls. Changes in these cells density following FMT correlated with IBS symptoms (diarrhea, bloating, and abdominal pain).

Critical Neurotransmitters in the Neuroimmune Network

Immune cells rely on cell-cell communication to specify and fine-tune their responses. They express an extensive network of cell communication modes, including a vast repertoire of cell surface and transmembrane receptors and ligands, membrane vesicles, junctions, ligand and voltage-gated ion channels, and transporters. During a crosstalk between the nervous system and the immune system these modes of cellular communication and the downstream signal transduction events are influenced by neurotransmitters present in the local tissue environments in an autocrine or paracrine fashion. Neurotransmitters thus influence innate and adaptive immune responses. In addition, immune cells send signals to the brain through cytokines, and are present in the brain to influence neural responses. Altered communication between the nervous and immune systems is emerging as a common feature in neurodegenerative and immunopathological diseases. Here, we present the mechanistic frameworks of immunostimulatory and immunosuppressive effects critical neurotransmitters - dopamine (3,4-dihydroxyphenethylamine), serotonin (5-hydroxytryptamine), substance P (trifluoroacetate salt powder), and L-glutamate - exert on lymphocytes and non-lymphoid immune cells. Furthermore, we discuss the possible roles neurotransmitter-driven neuroimmune networks play in the pathogenesis of neurodegenerative disorders, autoimmune diseases, cancer, and outline potential clinical implications of balancing neuroimmune crosstalk by therapeutic modulation.

Fecal and Mucosa-Associated Intestinal Microbiota in Patients with Diarrhea-Predominant Irritable Bowel Syndrome

BACKGROUND

Irritable bowel syndrome (IBS) has been associated with changes in the intestinal microbiota. Only a few studies have explored differences in the mucosa-associated microbiota between IBS patients and healthy controls (HC).

AIMS

To characterize and compare the microbiota in mucosal and fecal samples from carefully selected patients with IBS-D and HC.

METHODS

The cohort was composed of 23 diarrhea-predominant IBS (IBS-D) patients and 24 HC. Fresh stool samples were collected from participants prior to the collection of colonic mucosal samples from an unprepped bowel. After DNA extraction, 16S rRNA genes were sequenced by 454 pyrosequencing and analyzed using the QIIME pipeline.

RESULTS

The fecal microbiota (luminal niche) of IBS-D patients was found to have reduced enteric richness compared to HC (P < 0.05), whereas no differences were observed between the two groups within the mucosal microbiota. Within the luminal niche, the relative proportions of Faecalibacterium genus were found to be lower in IBS-D than in HC and the Dorea genus was higher in IBS-D. None of the taxa proportions were significantly different in IBS-D patients versus HC using an FDR of ≤ 0.1 when analyzing samples that appeared in > 25% samples of either niche.

CONCLUSION

Fecal and mucosal microbiota of IBS-D patients and HC are very similar and are not sufficient to explain the reported altered physiology and symptomatology of IBS-D. Future studies should investigate intestinal microbiome-dependent functional activity in addition to the fecal and mucosal-associated microbial composition.

Genetic variants of immune-related genes IL17F and IL10 are associated with functional dyspepsia: A case-control study

BACKGROUND

Low-grade inflammation may play an important role in pathogenesis of functional dyspepsia (FD). Since cytokines may influence gastric mucosal inflammation, which is associated with FD, we evaluated singe nucleotide polymorphisms (SNPs) of pro-inflammatory IL17F and anti-inflammatory IL10 cytokine genes in patients with FD and healthy subjects (HS).

METHODS

Two hundred and thirty-seven consecutive patients with FD (Rome III) and 250 HS were genotyped for IL17F (rs2397084: A/G, rs763780: T/C) and IL10 (rs1800896: G/A, rs1800871: C/T) (PCR-RFLP).

RESULTS

Patients with FD [173 (73%) men, age 38.4±12 years] were comparable with HS [195 (78%) men, age 37.3±12 years] with respect to age and gender. Out of 237 patients, 26 (11%) had epigastric pain, 55 (23.2%) had post-prandial distress syndromes (EPS, PDS), and 156 (65.8%) had EPS-PDS overlap. Among 237 patients with FD, GG (variant) genotype of IL17F (rs2397084) was more common than HS [15 (6.3%) vs. 4 (1.6%), p=0.015, odds ratio (OR)=4.0, 95% confidence interval (CI)=1.3-12.3]. IL17F (rs763780) and IL10 (rs1800896) were comparable among patients and HS (p=0.56, 0.28), respectively. However, TT (variant) genotype of IL10 (rs1800871) was more common among patients than HS [39 (16.5%) vs. 32 (12.8%), p=0.06, OR=1.7, 95% CI=0.98-2.98]. SNPs of IL17F and IL10 (rs2397084, rs763780, rs1800896 and rs1800871) were comparable among patients among sub-types of FD (p=0.80 and 0.44).

CONCLUSION

SNPs of IL17F (rs2397084) and IL10 (rs1800871) genes are associated with FD.

Neuroimmune factors in functional gastrointestinal disorders: A focus on irritable bowel syndrome

BACKGROUND

Abnormal abdominal pain perception is the most bothersome and difficult to treat symptom of functional gastrointestinal disorders (FGIDs). Visceral pain stimuli are perceived and transmitted by afferent neurons residing in the dorsal root ganglia that have sensory nerve endings in the gut wall and mesentery. Accumulating evidence indicates that peripheral activation and sensitization of these sensory nerve endings by bioactive mediators released by activated immune cells, in particular mast cells, can lead to aberrant neuroimmune interactions and the development and maintenance of visceral hypersensitivity. Besides direct neuronal activation, low concentrations of proteases, histamine, and serotonin can chronically sensitize nociceptors, such as TRP channels, leading to persistent aberrant pain perception.

PURPOSE

This review discusses the potential mechanisms underlying aberrant neuroimmune interactions in peripheral sensitization of sensory nerves. A better understanding of the cells, mediators, and molecular mechanisms triggering persistent aberrant neuroimmune interactions brings new insights into their contribution to the physiology and pathophysiology of visceral pain perception and provides novel opportunities for more efficient therapeutic treatments for these disorders.

Lactobacillus casei DG and its postbiotic reduce the inflammatory mucosal response: an ex-vivo organ culture model of post-infectious irritable bowel syndrome

BACKGROUND

The evidence on the role of gut microbiota in post-infectious irritable bowel syndrome (PI-IBS) is convincing. Lactobacillus spp. positively affect IBS symptoms, although the mechanisms through which probiotics exert their beneficial effects are largely unknown. The aim of the study is to evaluate the role of Lactobacillus casei DG (LC-DG) and its postbiotic (PB) in modulating the inflammatory/immune-response in PI-IBS in an ex-vivo organ culture model.

METHODS

Ex vivo cultures of ileal and colonic mucosa from 10 PI-IBS, diarrhea predominant subtype (D) patients, and 10 healthy controls (HC) were treated with LPS, LC-DG and PB. Interleukin (IL)-1α, IL-6, IL-8 and IL-10 mRNA levels were assessed by real-time PCR and Toll like receptor 4 (TLR-4) protein expression by Western blotting.

RESULTS

At baseline, IL-1α, IL-6 and IL-8 mRNA levels as well as TLR-4 protein expression were significantly higher while IL-10 mRNA levels were lower in PI-IBS D than in HC in both ileum and colon. LC-DG and PB significantly reduced the mRNA levels of pro-inflammatory cytokines and TLR-4 while increased that of IL-10 after LPS stimulation. The protective effect was more pronounced for PB than LC-DG treatment.

CONCLUSION

LC-DG and its PB attenuate the inflammatory mucosal response in an ex-vivo organ culture model of PI-IBS D.

Deciphering the pathophysiology of irritable bowel syndrome and functional gastrointestinal disorders-an alternative model for pathogenesis: cytokine controlled transepithelial multi-feedback loop

A working theoretical model for irritable bowel syndrome (IBS) and other functional gastrointestinal disorders (FGIDs) does not exist, hampered by the lack of any clear cut invention that address all symptom and signs of the disease. Reports of cessation of symptom and signs of both major types of IBS have been published using a non-systemic, topically active agent-high potency polymerized cross-linked sucralfate (HPPCLS). The unique clinical effect of this non-systemic agent restricted to the luminal surface of the gut provides opportunity to elaborate on an alternative working model for the pathogenesis of IBS and FGIDs. While the chemical determinants of HPPCLS and the mucosal lining contribute to the clinical effects, the sequence of events resides in the functional interplay among elements within the mucosa itself. The proposed model assumes that failure of a pre-existing genomic-controlled surveillance of the epithelium localized to the luminal surface triggers primary and secondary immune activation of inflammation intent on restoring epithelial homeostasis. Delayed restoration of homeostasis results in all the symptoms, signs and likely molecular events that characterize IBS and FGIDs.

Irritable bowel syndrome

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.

Changes in the Abundance of Faecalibacterium prausnitzii Phylogroups I and II in the Intestinal Mucosa of Inflammatory Bowel Disease and Patients with Colorectal Cancer

BACKGROUND

Faecalibacterium prausnitzii comprises 2 phylogroups, whose abundance in healthy and diseased gut and in conjunction with Escherichia coli has not yet been studied. This work aims to determine the contribution of F. prausnitzii phylogroups I and II in intestinal disease and to assess their potential diagnostic usefulness as biomarkers for gut diseases.

METHODS

Total F. prausnitzii, its phylogroups, and E. coli loads were determined by quantitative polymerase chain reaction targeting the 16S rRNA gene on biopsies from 31 healthy controls (H), 45 patients with Crohn's disease (CD), 25 patients with ulcerative colitis, 10 patients with irritable bowel syndrome, and 20 patients with colorectal cancer. Data were normalized to total bacterial counts and analyzed according to patients' disease location and clinical characteristics.

RESULTS

Lower levels of both total F. prausnitzii and phylogroup I were found in subjects with CD, ulcerative colitis, and colorectal cancer (P < 0.001) compared with H subjects. Phylogroup I load was a better biomarker than total F. prausnitzii to discriminate subjects with gut disorders from H. Phylogroup II depletion was observed only in patients with CD (P < 0.001) and can be potentially applied to differentiate ulcerative pancolitis from colonic CD. No statistically significant correlation between E. coli and any of the 2 F. prausnitzii phylogroups was found in any group of patients or by inflammatory bowel disease location. Phylogroup I was lower in active patients with CD, whereas those CD with intestinal resection showed a reduction in phylogroup II. Treatments with mesalazine and immunosuppressants did not result in the recovery of F. prausnitzii phylogroups abundance.

CONCLUSIONS

F. prausnitzii phylogroup I was depleted in CD, ulcerative colitis, and colorectal cancer, whereas phylogroup II was specifically reduced in CD. Quantification of F. prausnitzii phylogroups and E. coli may help to identify gut disorders and to classify inflammatory bowel disease location.

The relationship between faecal-associated and mucosal-associated microbiota in irritable bowel syndrome patients and healthy subjects

BACKGROUND

The faecal-associated microbiota is commonly seen as a surrogate of the mucosal-associated microbiota. However, previous studies indicate that they are different. Furthermore, analyses of the mucosal microbiota are commonly done after standard bowel cleansing, affecting the microbial composition.

AIM

To compare the mucosal-associated microbiota, obtained from unprepared colon, with faecal-associated microbiota in healthy subjects and irritable bowel syndrome (IBS) patients.

METHODS

Faecal and mucosal biopsies were obtained from 33 IBS patients and 16 healthy controls. Of IBS patients, 49% belonged to the diarrhoea-predominant subgroup and 80% suffered from IBS symptoms during at least 5 years. Biopsies were collected from unprepared sigmoid colon and faecal samples a day before colonoscopy. Microbiota analyses were performed with a phylogenetic microarray and redundancy discriminant analysis.

RESULTS

The composition of the mucosal- and the faecal-associated microbiota in unprepared sigmoid colon differs significantly (P = 0.002). Clinical characteristics of IBS did not correlate with this difference. Bacteroidetes dominate the mucosal-associated microbiota. Firmicutes, Actinobacteria and Proteobacteria dominate the faecal-associated microbiota. Healthy subjects had a significantly higher (P < 0.005) abundance (1.9%) of the bacterial group uncultured Clostridiales I in the mucosal-associated microbiota than IBS patients (0.3%). Bacterial diversity was higher in faecal- compared with mucosal-associated microbiota in IBS patients (P < 0.005). No differences were found in healthy subjects.

CONCLUSIONS

Differences in the mucosal-associated microbiota between healthy individuals and IBS patients are minimal (one bacterial group) compared to differences in the faecal microbiota of both groups (53 bacterial groups). Microbial aberrations characterising IBS are more pronounced in the faeces than in the mucosa.

Cytokine Response after Stimulation with Key Commensal Bacteria Differ in Post-Infectious Irritable Bowel Syndrome (PI-IBS) Patients Compared to Healthy Controls

BACKGROUND

Microbial dysbiosis and prolonged immune activation resulting in low-grade inflammation and intestinal barrier dysfunction have been suggested to be underlying causes of post-infectious irritable bowel syndrome (PI-IBS). The aim of this study was to evaluate the difference in cytokine response between mucosal specimens of PI-IBS patients and healthy controls (HC) after ex vivo stimulation with key anaerobic bacteria.

METHODS

Colonic biopsies from 11 PI-IBS patients and 10 HC were stimulated ex vivo with the commensal bacteria Bacteroides ovatus, Ruminococcus gnavus, Akkermansia muciniphila, Subdoligranulum variabile and Eubacterium limosum, respectively. The cytokine release (IL-1β, IL-2, IL-8, IL-10, IL-13, IL-17, TNF-α and IFN-γ) in stimulation supernatants was analyzed using the LUMINEX assay. Comparison of cytokine release between PI-IBS patients and healthy controls was performed taking both unstimulated and bacterially stimulated mucosal specimens into account.

KEY RESULTS

IL-13 release from mucosal specimens without bacterial stimulation was significantly lower in PI-IBS patients compared to HC (p < 0.05). After stimulation with Subdoligranulum variabile, IL-1β release from PI-IBS patients was significantly increased compared to HC (p < 0.05). Stimulation with Eubacterium limosum resulted in a significantly decreased IL-10 release in HC compared to PI-IBS patients (p < 0.05) and a tendency to decreased IL-13 release in HC compared to PI-IBS patients (p = 0.07).

CONCLUSIONS & INFERENCES

PI-IBS patients differ from HC with regard to cytokine release ex vivo after stimulation with selected commensal bacteria. Hence, our results support that the pathogenesis of PI-IBS comprises an altered immune response against commensal gut microbes.

Cannabinoids regulate intestinal motor function and electrophysiological activity of myocytes in rodents

BACKGROUND AND AIMS

This study aims to investigate the effects of cannabinoid (CB)1 and CB2 receptor ligands on intestinal motor function and muscular electrophysiological activity in rodent gastrointestinal (GI) tract.

METHODS

Lipopolysaccharide (LPS) was used to induce intestinal hypomotility. The effect of selective CB1 and CB2 agonists and antagonists on contractility of the muscle strips from rat jejunum was measured using organ bath, and the membrane potential of the jejunal smooth muscle cells was recorded with intracellular microelectrodes. The single cell patch clamp technique was applied to record delayed rectifying potassium currents (IKV) and spontaneous transient outward currents (STOC).

RESULTS

LPS significantly reduced contractility of the smooth muscle strips (p <0.010) and caused hyperpolarization of membrane potential of the smooth muscle cells (p <0.010). This LPS-induced effect was reversed by AM251 and AM630, selective CB1 and CB2 antagonists, respectively, which promoted contractions of smooth muscle strips and triggered cell depolarization (p <0.010). LPS-induced changes were further enhanced in the presence of CB agonists, HU210 and WIN55 (p <0.050 or p <0.010). No effect of HU210 or AM251 on IKV and STOC has been observed. This ex vivo study suggests that CB1 and CB2 receptors are involved in intestinal motor function in normal and LPS-induced pathological states and the regulation of the membrane potential of smooth muscle cells is very likely one of the effective mechanisms.

CONCLUSIONS

This is one of the first reports on neuronal regulation of intestinal motility through CB-dependent pathways with potential application in the treatment of inflammatory and functional GI disorders.

Nerve fiber outgrowth is increased in the intestinal mucosa of patients with irritable bowel syndrome

BACKGROUND & AIMS

Mediators released by the intestinal mucosa of patients with irritable bowel syndrome (IBS) affect the function of enteric and extrinsic sensory nerves, which can contribute to the development of symptoms. Little is known about the effects of mucosal mediators on intestinal neuroplasticity. We investigated how these mediators affect the phenotypes of colonic mucosa nerve fibers, neuron differentiation, and fiber outgrowth.

METHODS

We analyzed mucosal biopsy samples collected from 101 patients with IBS and 23 asymptomatic healthy individuals (controls). We measured levels of neuronal-specific enolase, growth-associated protein 43, nerve growth factor (NGF), and tyrosine kinase receptor A (NTRK1) by immunohistochemistry and enzyme-linked immunosorbent assay. Primary rat enteric neurons and human SH-SY5Y cells were incubated with supernatants from the mucosal biopsies and analyzed by morphometric and polymerase chain reaction analyses.

RESULTS

Compared with mucosal tissues of controls, mucosa from patients with IBS had a significant increase in the area of lamina propria occupied by neuronal-specific enolase-positive (57.7% increase) and growth-associated protein 43-positive fibers (56.1% increase) and staining density of NGF (89.3% increase) (P < .05 for all). Levels of NGF protein were also increased in tissues from patients with IBS vs controls (18% increase; P = .16) along with levels of NTRK1 (64% increase; P < .05). Mucosal supernatants from tissues of patients with IBS induced higher levels of neuritogenesis in primary culture of enteric neurons, compared with controls, and more NGF-dependent neuronal sprouting in SH-SY5Y cells.

CONCLUSIONS

Nerve fiber density and sprouting, as well as expression of NGF and NTRK1, are significantly increased in mucosal tissues of patients with IBS. Mucosal mediators participate to these neuroplastic changes.

Altered faecal and mucosal microbial composition in post-infectious irritable bowel syndrome patients correlates with mucosal lymphocyte phenotypes and psychological distress

BACKGROUND

A subset of irritable bowel syndrome (IBS) patients, denoted post-infectious IBS (PI-IBS), develop symptoms after an enteric infection. Bacterial dysbiosis and mucosal inflammation have been proposed to be involved in the pathophysiology of this entity.

AIM

To characterise the mucosal and faecal microbiota in PI-IBS, general IBS and healthy controls, and to investigate associations between the microbiota and the mucosal immune system.

METHODS

Mucosal biopsies and faeces were collected from 13 PI-IBS patients, 19 general IBS patients and 16 healthy controls. Global bacterial composition was determined by generating 16S rRNA amplicons that were examined by phylogenetic microarray hybridisation, principal component and redundancy analysis. We correlated previously reported lymphocyte proportions with the microbiota.

RESULTS

Faecal microbiota composition of PI-IBS patients differed significantly from both general IBS patients and healthy controls (P < 0.02). Both mucosal (P < 0.01) and faecal (P = 0.05) microbial diversity were reduced in PI-IBS compared to healthy controls. In the intraepithelial lymphocytes the previously published proportion of CD8(+) CD45RA(+) was negatively correlated with mucosal microbial diversity (P < 0.005). The previously published number of lamina propria lymphocytes was negatively correlated with mucosal microbial diversity (P < 0.05). Faecal microbial diversity was significantly negatively correlated with the Hospital Anxiety and Depression scale (P < 0.05).

CONCLUSIONS

We present data that distinguishes the intestinal microbiota of PI-IBS patients from that of both general IBS patients and HC. The microbial composition is significantly associated with the HADs score and alterations in lymphocyte subsets proportions.

Alterations of colonic contractility in an interleukin-10 knockout mouse model of inflammatory bowel disease

Background/Aims

Inflammatory bowel disease is commonly accompanied by colonic dysmotility and causes changes in intestinal smooth muscle contractility. In this study, colonic smooth muscle contractility in a chronic inflammatory condition was investigated using smooth muscle tissues prepared from interleukin-10 knockout (IL-10^−/−) mice.

Methods

Prepared smooth muscle sections were placed in an organ bath system. Cholinergic and nitrergic neuronal responses were observed using carbachol and electrical field stimulation with L-NG-nitroarginine methyl ester (L-NAME). The expression of interstitial cells of Cajal (ICC) networks, muscarinic receptors, neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS) was observed via immunofluorescent staining.

Results

The spontaneous contractility and expression of ICC networks in the proximal and distal colon was significantly decreased in IL-10^−/− mice compared to IL-10^+/+ mice. The contractility in response to carbachol was significantly decreased in the proximal colon of IL-10^−/− mice compared to IL-10^+/+ mice, but no significant difference was found in the distal colon. In addition, the expression of muscarinic receptor type 2 was reduced in the proximal colon of IL-10^−/− mice. The nictric oxide-mediated relaxation after electrical field stimulation was significantly decreased in the proximal and distal colon of IL-10^−/− mice. In inflamed colon, the expression of nNOS decreased, whereas the expression of iNOS increased.

Conclusions

These results suggest that damage to the ICC network and NOS system in the proximal and distal colon, as well as damage to the smooth muscle cholinergic receptor in the proximal colon may play an important role in the dysmotility of the inflamed colon.

Systematic review with meta-analysis: post-infectious functional dyspepsia

BACKGROUND

The prevalence of functional dyspepsia (FD) following infectious gastroenteritis has not been systematically reviewed.

AIM

To conduct a systematic review and calculate the summary odds ratio (OR) for the development of FD following infectious gastroenteritis, as compared to a control population.

METHODS

Published studies in PubMed, EmBASE, and Cochrane Database and abstracts from standard sources were screened for eligible studies. Data from studies meeting inclusion criteria were pooled for meta-analysis.

RESULTS

Nineteen studies were eligible for inclusion. The mean prevalence of FD following acute gastroenteritis (AGE) was 9.55% (FD, n = 909; AGE, n = 9517) in adult populations. The summary OR for the development of post-infectious FD was 2.54 (95% CI = 1.76-3.65) at more than 6 months after AGE, as compared to the prevalence in controls within the same population. This is compared with the summary OR (3.51; 95% CI = 2.05-6.00) for the development of post-infectious irritable bowel syndrome (IBS) in the same population at more than 6 months after AGE. There was significant statistical heterogeneity with an I(2) of 72.8% for the summary OR of post-infectious FD. Several pathogens, including Salmonella spp., Escherichia coli O157, Campylobacter jejuni, Giardia lamblia and Norovirus have been shown to be associated with post-infectious FD symptoms.

CONCLUSIONS

Infectious gastroenteritis is associated with an increased risk for subsequent dyspepsia as well as for irritable bowel syndrome. Post-infectious FD and post-infectious irritable bowel syndrome may represent different aspects of the same pathophysiology. Further studies will be needed to determine this.

Neuroplasticity and dysfunction after gastrointestinal inflammation

The gastrointestinal tract is innervated by several distinct populations of neurons, whose cell bodies either reside within (intrinsic) or outside (extrinsic) the gastrointestinal wall. Normally, most individuals are unaware of the continuous, complicated functions of these neurons. However, for patients with gastrointestinal disorders, such as IBD and IBS, altered gastrointestinal motility, discomfort and pain are common, debilitating symptoms. Although bouts of intestinal inflammation underlie the symptoms associated with IBD, increasing preclinical and clinical evidence indicates that infection and inflammation are also key risk factors for the development of other gastrointestinal disorders. Notably, a strong correlation exists between prior exposure to gut infection and symptom occurrence in IBS. This Review discusses the evidence for neuroplasticity (structural, synaptic or intrinsic changes that alter neuronal function) affecting gastrointestinal function. Such changes are evident during inflammation and, in many cases, long after healing of the damaged tissues, when the nervous system fails to reset back to normal. Neuroplasticity within distinct populations of neurons has a fundamental role in the aberrant motility, secretion and sensation associated with common clinical gastrointestinal disorders. To find appropriate therapeutic treatments for these disorders, the extent and time course of neuroplasticity must be fully appreciated.

Aberrant mucosal lymphocyte number and subsets in the colon of post-infectious irritable bowel syndrome patients

BACKGROUND

Irritable bowel syndrome (IBS) is characterized by chronic abdominal symptoms such as pain, discomfort, and altered bowel habits. A subset of IBS patients, denoted as post-infectious IBS (PI-IBS) patients, develop symptoms after an enteric infection. Distinct abnormalities in the gut mucosa, including mucosal inflammation, have been proposed to contribute to or be the cause of PI-IBS. This study investigated lymphocyte subsets in PI-IBS patients compared to healthy controls.

MATERIALS AND METHODS

Ten PI-IBS patients and nine healthy controls participated. All PI-IBS patients met the Rome III diagnostic criteria for IBS and reported sustained symptoms at least 1 year after an episode of acute gastroenteritis. Intraepithelial lymphocytes and lamina propria lymphocytes (LPLs), isolated from mucosal tissue samples, were stained and analyzed for a comprehensive set of cell markers using flow cytometry.

RESULTS

The number of LPLs in PI-IBS was significantly increased compared to those in healthy controls (p < 0.05). PI-IBS patients showed significantly increased proportions of CD45RO(+) CD4(+) activated/memory T cells (p < 0.05) and double-positive CD4(+) CD8(+) cells (p < 0.05), respectively, in the lamina propria. The number of CD19(+) LPLs was decreased in PI-IBS patients compared to healthy controls (p < 0.001).

CONCLUSION

This study presents new evidence that PI-IBS is associated with a sustained aberrant mucosal immune response and support future studies of anti-inflammatory or immune-modulating treatments in these patients.

Increased gastric chromogranin A cell density following changes to diets of patients with irritable bowel syndrome

The gut endocrine cells control and regulate several functions of the gastrointestinal tract. They have been reported to be abnormal in irritable bowel syndrome (IBS), with alterations occurring in several functions regulated by these cells. Furthermore, it has been established that gut endocrine cells interact with the gut lumen contents, particularly the nutrients. The present study was undertaken to establish whether the positive outcome of dietary guidance observed in patients suffering from IBS is associated with a change in gastric endocrine cells. A total of 46 patients with IBS participated in the present study, of which 14 completed all aspects. These patients included nine females and five males with a mean age of 34 years (range, 20–45 years). In the healthy control group, nine females and five males, with a mean age of 54 years (range 26–70 years) were selected. The patients and controls underwent gastroscopy with biopsy samples taken from the corpus and antrum of the stomach. Each patient attended three sessions that lasted ~45 min each, and received individual guidance on their dietary management. The patients followed the diet prescribed for a minimum of three months, then further samples were taken using a method similar to that used for the initial biopsies. The biopsy samples were immunostained using the avidin-biotin complex method for chromogranin A (CgA) and quantified by computerized image analysis. The patients with IBS presented a low density of CgA compared with the controls. The density of CgA increased in these patients following dietary guidance and changes in food intake. The present observations emphasized the interaction between food intake and gut endocrine cells. The current study also suggests that the positive effects of dietary guidance may be attributed to changes in gut endocrine cell density.

A role for the gut microbiota in IBS

The past decade has witnessed an explosion of knowledge regarding the vast microbial community that resides within our intestine-the gut microbiota. The topic has generated great expectations in terms of gaining a better understanding of disorders ranging from IBD to metabolic disorders and obesity. IBS is a condition for which investigators have long been in search of plausible underlying pathogeneses and it is inevitable that altered composition or function of the gut microbiota will be considered as a potential aetiological factor in at least a subset of patients with IBS. This Review describes the evidence implicating the gut microbiota in not only the expression of the intestinal manifestations of IBS, but also the psychiatric morbidity that coexists in up to 80% of patients with IBS. The evidence described herein ranges from proof-of-concept studies in animals to observational studies and clinical trials in humans. The gut microbiota is subject to influences from a diverse range of factors including diet, antibiotic usage, infection and stress. These factors have previously been implicated in the pathophysiology of IBS and further prompt consideration of a role for the gut microbiota in IBS.

Role of mast cells and protease activated receptor-2 in irritable bowel syndrome

AIM: To investigate the role of mast cells and protease activated receptor-2 (PAR-2) in irritable bowel syndrome (IBS).

METHODS: A total of 90 subjects were divided into a diarrhea-predominant irritable bowel syndrome (IBS-D) group (n = 60) and a normal control group (n = 30), all of them were selected from digestive outpatient department of Nanjing Hospital Affiliated to Nanjing Medical University from January 2012 to December 2012. The expression of mast cells and PAR-2 was detected by immunohistochemistry, and the expression of Occludin was detected by Western blot.

RESULTS: Immunohistochemistry analysis showed that compared with the normal control group, the expression of both mast cells and PAR-2 was significantly higher in the IBS-D group (5.20 ± 2.78 vs 1.40 ± 0.55, P < 0.05; 3.20 ± 1.64 vs 1.20 ± 0.45, P < 0.05). Western blot analysis indicated that the expression of Occludin decreased significantly in the IBS-D group compared with the normal control group (2108.33 ± 59.58 vs 3113.00 ± 77.74, P < 0.01).

CONCLUSION: Our study suggests that in IBS-D subjects, overexpressed and activated mast cells may stimulate PAR-2 and lead to the damage of intercellular tight junctions.

High-potency sucralfate prevents and rapidly reverses chemo-radiation mucositis in a patient with stage 4b head and neck cancer

AIM: To study usefulness of high-potency sucralfate (HPS) in a patient with chemoradiation mucositis and discuss its mechanism of action.

METHODS: HPS, a non-covalently cross-link of sucralfate, cations and bidentate anionic chelators, has a maintains a surface concentration of sucralfate 3 h following administration that is 7-23 fold that possible with standard-potency sucralfate. The accelerated mucosal healing and pain alleviation of HPS in patients with erosive esophageal reflux, prompted its use in this patient with chemoradiation mucositis of the oropharynx and alimentary tract. A literature-based review of the immuno-modulatory effects of sucralfate is discussed.

RESULTS: Within 48 h of intervention: (1) there was complete disappearance of oral mucositis lesions; tenderness with (2) patient-reported disappearance of pain, nausea and diarrhea; patient required (3) no opiate analgesia and (4) no tube-feeding supplements to regular diet. Dysgeusia and xerostomia persisted. A modified Naranjo Questionnaire score of 10 supported the likelihood that HPS intervention caused the observed clinical effects. No adverse reactions noted.

CONCLUSION: In this patient HPS was useful to treat chemo-radiation mucositis of the oropharynx and alimentary tract. HPS may directly or indirectly facilitate an immunomodulatory mechanism involving accelerated growth factor activation, which may be a new target for therapeutic intervention in such patients.

Stress and gene expression of individuals with chronic abdominal pain

BACKGROUND

Research examining the role of stress in gastrointestinal (GI) symptoms such as chronic abdominal pain (CAP) is controversial. The purpose of this study was to examine the expression of genes involved in metabolic stress and toxicity in men and women with high and low levels of perceived stress with and without CAP.

METHODS

Data and samples were collected and the expression of genes involved in metabolic stress and toxicity was analyzed in 26 individuals who had consented to participate in a natural history protocol. Subjects completed the 10-item Perceived Stress scale (PSS). Fasting participants' peripheral whole blood was collected for proteomic and genomic studies. Polymerase chain reaction (PCR) array was used to analyze the expression of 84 key genes involved in human stress and toxicity plus 5 housekeeping genes. Plasma interleukin-1 alpha (IL-1α) protein was quantified via enzyme-linked immunosorbent assay (ELISA).

RESULTS

Interleukin-1 alpha gene (IL1A) was upregulated in females with high stress versus females with low stress by 2.58-fold (95% CI [0.88, 4.28]). IL1A was upregulated in participants with high stress and CAP versus those with low stress and CAP by 3.47-fold (95% CI [1.14, 5.80]).

CONCLUSIONS

An upregulation of the gene coding the pro-inflammatory cytokine IL-1α suggests that the mechanism behind stress-related changes in GI symptoms is pro-inflammatory in nature. The results of this study contribute to the knowledge of the mechanism behind stress-related CAP symptoms and gender differences associated with these disorders.

Overlap between functional GI disorders and other functional syndromes: what are the underlying mechanisms?

BACKGROUND

Irritable bowel syndrome and other gastrointestinal (GI) and non-GI disorders such as functional dyspepsia, fibromyalgia, temporomandibular joint disorder, interstitial cystitis/painful bladder syndrome, and chronic fatigue syndrome are known as functional pain syndromes. They commonly coexist within the same individual. The pathophysiologic mechanisms of these disorders are not well understood, but it has been hypothesized that they share a common pathogenesis.

PURPOSE

The objective of this review is to discuss the proposed pathophysiologic mechanisms, which have been similarly studied in these conditions. These mechanisms include enhanced pain perception, altered regional brain activation, infectious etiologies, dysregulations in immune and neuroendocrine function, and genetic susceptibility. Studies suggest that these functional disorders are multifactorial, but factors which increase the vulnerability of developing these conditions are shared.

Functional diarrhea

Chronic diarrhea is a frequent and challenging problem in clinical medicine. In a considerable subgroup of these, no underlying cause is identified and this is referred to as functional diarrhea. A consensus definition for functional diarrhea is based on loose stool consistency and chronicity and absence of coexisting irritable bowel syndrome. Underlying pathophysiology includes rapid intestinal transit, which may be worsened by stress or be triggered by a preceding infectious gastroenteritis. Diagnostic work-up aims at exclusion of underlying organic disease. Treatment starts with dietary adjustments, aiming at decreasing nutrients that enhance transit and stool and at identifying precipitating food items.

Pro-inflammatory chemokine C-C motif ligand 16 (CCL-16) dysregulation in irritable bowel syndrome (IBS): a pilot study

BACKGROUND

Irritable bowel syndrome (IBS) is a serious health problem that affects an estimated 10-15% of people worldwide and has economic consequences in the United States of over $30 billion annually. In the US, IBS affects all races and both sexes, with more females than males (2:1) reporting symptoms consistent with IBS. Although the etiology of this functional gastrointestinal disorder is unknown, literature suggests that a subclinical inflammatory component has a role in the etiologic mechanisms underlying IBS. The aim of this study was to evaluate the gene expression of inflammatory biomarkers in patients with and without IBS and among different IBS phenotypes.

METHODS

Irritable bowel syndrome patients (n=12) that met Rome III Criteria for IBS longer than 6months were compared with healthy matched controls (n=12). Peripheral whole blood from fasting participants was collected and RNA was extracted. The expression of 96 inflammatory genes was then analyzed using a custom quantitative real-time PCR array.

KEY RESULTS

CCL-16 gene expression was upregulated by 7.46-fold in IBS patients when compared with controls. CCL-16 was overexpressed by over 130-fold in IBS-constipation patients when compared with both controls and IBS-diarrhea patients.

CONCLUSIONS & INFERENCES

These results further suggest a subclinical inflammatory component underlying IBS. To better understand the phenotypic differences in IBS it is important to broaden the study of these inflammatory and other biomarkers.

Global and deep molecular analysis of microbiota signatures in fecal samples from patients with irritable bowel syndrome

BACKGROUND & AIMS

Irritable bowel syndrome (IBS) has been associated with disruptions to the intestinal microbiota, but studies have had limited power, coverage, and depth of analysis. We aimed to define microbial populations that can be used discriminate the fecal microbiota of patients with IBS from that of healthy subjects and correlate these with IBS intestinal symptom scores.

METHODS

The microbiota composition was assessed by global and deep molecular analysis of fecal samples from 62 patients with IBS patients and 46 healthy individuals (controls). We used a comprehensive and highly reproducible phylogenetic microarray in combination with quantitative polymerase chain reaction.

RESULTS

The intestinal microbiota of IBS patients differed significantly (P = .0005) from that of controls. The microbiota of patients, compared with controls, had a 2-fold increased ratio of the Firmicutes to Bacteroidetes (P = .0002). This resulted from an approximately 1.5-fold increase in numbers of Dorea, Ruminococcus, and Clostridium spp (P < .005); a 2-fold decrease in the number of Bacteroidetes (P < .0001); a 1.5-fold decrease in numbers of Bifidobacterium and Faecalibacterium spp (P < .05); and, when present, a 4-fold lower average number of methanogens (3.50 × 10(7) vs 8.74 × 10(6) cells/g feces; P = .003). Correlation analysis of the microbial groups and IBS symptom scores indicated the involvement of several groups of Firmicutes and Proteobacteria in the pathogenesis of IBS.

CONCLUSIONS

Global and deep molecular analysis of fecal samples indicates that patients with IBS have a different composition of microbiota. This information might be used to develop better diagnostics and ultimately treatments for IBS.

Do probiotics improve symptoms in patients with irritable bowel syndrome?

There is increasing evidence that inflammation or a disturbance of the flora within the gut might contribute to the pathogenesis of irritable bowel syndrome (IBS), at least in a proportion of cases. As a consequence it has been speculated that, as some probiotic bacteria have a range of anti-inflammatory and immunomodulatory properties, the administration of such organisms might prove to be beneficial in this condition. It has to be acknowledged that the quality and design of trials of probiotics in IBS has been somewhat variable but the majority have shown benefit, although some bacteria appear to be more effective than others. More recent studies using Bifidobacterium infantis 35624 and Bifidobacterium lactis DN-173-010 have given particularly encouraging results. Issues for the future include determining which organisms are most effective, defining optimal doses, comparing methods of delivery and assessing the role of mixtures or the addition of prebiotics.

Methotrexate-induced intestinal mucositis delays gastric emptying and gastrointestinal transit of liquids in awake rats

CONTEXT: Methotrexate and other anticancer agents can induce intestinal mucositis, which is one of the most common limiting factor that prevent further dose escalation of the methotrexate. OBJECTIVES: To evaluate the gastric emptying and gastrointestinal transit of liquids in methotrexate-induced intestinal mucositis. METHODS: Wistar rats received methotrexate (2.5 mg/kg/day for 3 days, subcutaneously) or saline. After 1, 3 and 7 days, sections of duodenum, jejunum and ileum were removed for assessment of epithelial damage and myeloperoxidase activity (biochemical marker of granulocyte infiltration). Others rats were pre-treated with methotrexate or saline, gavage-fed after 3 or 7 days with a standard test liquid meal, and sacrificed 10, 20 or 30-min later. Gastric and small intestine dye recoveries were measured by spectrophotometry. RESULTS: After 3 days of methotrexate, there was an epithelial intestinal damage in all segments, with myeloperoxidase activity increase in both in duodenum and ileum. Seven days after methotrexate, we observed a complete reversion of this intestinal damage. There was an increase in gastric dye recoveries after 10, 20, and 30-min post-prandial intervals after 3 days, but not after 7 days, of methotrexate. Intestine dye recoveries were decreased in the first and second segments at 10 min, in the third at 20 min, and in the second and third at 30 min, only after 3 days of methotrexate treatment. CONCLUSION: Methotrexate-induced intestinal mucositis delays gastric emptying and gastrointestinal transit of liquids in awake rats.

Advances in understanding the relationship between mast cells and irritable bowel syndrome

The pathogenesis of irritable bowel syndrome (IBS) is very complicated. At present, it is generally believed that IBS is related to infection and inflammation, visceral hypersensitivity, gastrointestinal neuro-endocrine-immune dysfunction, psychological stress, intestinal food allergy, and other factors. Recently, attention has been directed to the role of low inflammation in the pathogenesis of IBS, especially the relationship between mast cells and IBS. Numerous studies have shown that the development of IBS involves abnormal alterations of mast cells. Mast cell degranulation leads to the release of many bioactive mediators that participate in the pathophysiological process of IBS. Abnormal alterations of mast cells in IBS are related not only to intestinal low-grade inflammation but also to other pathogenic factors.

The Incidence and gastrointestinal infectious risk of functional gastrointestinal disorders in a healthy US adult population

OBJECTIVES

Functional gastrointestinal disorders (FGDs) are recognized sequelae of infectious gastroenteritis (IGE). Within the active duty military population, a group with known high IGE rates, the population-based incidence, risk factors, and attributable burden of care referable to FGD after IGE are poorly defined.

METHODS

Using electronic medical encounter data (1999-2007) on active duty US military, a matched, case-control study describing the epidemiology and risk determinants of FGD (irritable bowel syndrome (IBS), functional constipation (FC), functional diarrhea (FD), dyspepsia (D)) was conducted. Incidence rates and duration of FGD-related medical care were estimated, and conditional logistic regression was utilized to evaluate FGD risk after IGE.

RESULTS

A total of 31,866 cases of FGD identified were distributed as follows: FC 55% (n=17,538), D 21.2% (n=6,750), FD 2.1% (n=674), IBS 28.5% (n=9,091). Previous IGE episodes were distributed as follows: specific bacterial pathogen (n=65, 1.2%), bacterial, with no pathogen specified (n=2155, 38.9%), protozoal (n=38, 0.7%), viral (n=3431, 61.9%). A significant association between IGE and all FGD (odds ratio (OR) 2.64; P<0.001) was seen, with highest risk for FD (OR 6.28, P<0.001) and IBS (OR 3.72, P<0.001), and moderate risk for FC (2.15, P<0.001) and D (OR 2.39, P<0.001). Risk generally increased with temporal proximity to, and bacterial etiology of, exposure. Duration of FGD-related care was prolonged with 22.7% having FGD-associated medical encounters 5 years after diagnosis.

CONCLUSIONS

FGD are common in this population at high risk for IGE. When considering effective countermeasures and mitigation strategies, attention directed toward prevention as well as the acute and chronic sequelae of these infections is needed.

Long-term downregulation of protease-activated receptor-2 expression in distal colon in rats following bacillary dysentery

The aim of this study was to determine changes of PAR-2 expression in distal colon and the sensitivity of colonic muscle to SLIGRL-NH2, the PAR-2-activating peptide (PAR-2-AP) following bacillary dysentery. Shigella flexneri was administrated intragastrically in healthy male rats to induce bacillary dysentery. The effect of SLIGRL-NH2 on the motility of colonic muscle strips were examined. The expression of PAR-2 was determined by immunohistochemistry and Western blotting. Intragastric administration of S.flexneri induced acute inflammation at the mucosa of the distal colon at 4-11 days, and the inflammation disappeared 18 days later. PAR-2-AP-induced TTX insensitive relaxation of the colonic muscle strips. This inhibitory effect on colonic circular muscle strips was reduced on days 11-35, but the carbachol-induced contraction did not change. PAR-2 was located at the colon smooth muscles cells and myenteric nerve plexus. The amount of PAR-2 expression in distal colon was down regulated on days 11-35. These data indicated that bacillary dysentery exerted a long-term downregulation on the expression of PAR-2 in distal colon. This might be the reason of the low sensitivity of the colon circular muscle strips to the PAR-2-AP-induced relaxation following intragastric administration of S.flexneri.

Investigation of esophageal sensation and biomechanical properties in functional chest pain

BACKGROUND

There is limited and conflicting data regarding the role of esophageal hypersensitivity in the pathogenesis of functional chest pain (FCP). We examined esophageal sensori-motor properties, mechanics, and symptoms in subjects with FCP.

METHODS

Esophageal balloon distension test was performed using impedance planimetry in 189 (m/f = 57/132) consecutive subjects with non-cardiac, non-reflux chest pain, and 36 (m/f = 16/20) healthy controls. The biomechanical and sensory properties of subjects with and without esophageal hypersensitivity were compared with controls. The frequency, intensity, and duration of chest pain were assessed.

KEY RESULTS

One hundred and forty-three (75%) subjects had esophageal hypersensitivity and 46 (25%) had normal sensitivity. Typical chest pain was reproduced in 105/143 (74%) subjects. Subjects with hypersensitivity demonstrated larger cross-sectional area (P < 0.001), decreased esophageal wall strain (P < 0.001) and distensibility (P < 0.001), and lower thresholds for perception (P < 0.01), discomfort (P < 0.01), and pain (P < 0.01) compared to those without hypersensitivity or healthy controls. Chest pain scores (mean +/- SD) for frequency, intensity and duration were 2.5 +/- 0.3, 2.2 +/- 0.2, and 2.2 +/- 0.2, respectively, and were similar between the two patient groups.

CONCLUSIONS & INFERENCES

Seventy-five per cent of subjects with FCP demonstrate esophageal hypersensitivity. Visceral hyperalgesia and sensori-motor dysfunction of the esophagus play a key role in the pathogenesis of chest pain.

Identification of single nucleotide polymorphisms in the TNFRSF17 gene and their association with gastrointestinal disorders

TNFRSF17 is preferentially expressed in mature B lymphocytes, and may be important for the development of B cells. TNFRSF17 is selected as a candidate susceptibility gene to IBD pathogenesis by our cDNA microarray analysis, and we showed the specific expression of TNFRSF17 in resting and activated CD19(+) cells obtained from human blood. We identified four SNPs (g-1729G>A, g.2295T>C, g.2445G>A and g.2493G>A) and one variation site (g.894delT) in the TNFRSF17 gene using direct sequencing analysis. In addition, the association of the genotype and allelic frequencies of these SNPs was studied in healthy controls and in patients with ulcerative colitis (UC) or irritable bowel syndrome (IBS). Although, the genotype and allelic frequencies of these SNPs, in the UC and IBS patients, were not significantly different from those in the healthy controls, the distribution of the AAG, GGA, AGG and AAA haplotypes, of the SNPs (g.-1729G>A, g.2445G> A and g.2493G>A) associated with the TNFRSF17 gene, in the UC patients, were notably different from those of the healthy controls (P = 0.002, 0.002, 4.7E-4 and 3.3E-6, respectively). Moreover, the frequencies of the AAG, AGG, GAG and GAA haplotypes were significantly different in the IBS patients compared to the healthy controls (P = 4.2E-5, 4.4E-17, 1.8E-22 and 1.6E-10, respectively). These results suggest that the haplotypes of the TNFRSF17 polymorphisms might be associated with UC and IBS susceptibility.

Colitis affects the smooth muscle and neural response to motilin in the rabbit antrum

BACKGROUND AND PURPOSE

The underlying mechanisms of gastric dysfunction during or after an episode of intestinal inflammation are poorly understood. This study investigated the effects of colitis on the contractile effects of motilin, an important endocrine regulator of gastric motility, in the antrum.

EXPERIMENTAL APPROACH

Myeloperoxidase (MPO) activity, NF-kappaB activity and motilin receptor density were determined in the antrum of rabbits 5 days after the induction of 2,4,6-trinitrobenzenesulphonic acid colitis. Smooth muscle and neural responses to motilin were studied in antral smooth muscle strips in vitro.

KEY RESULTS

Colitis did not affect MPO activity, but increased NF-kappaB activity in the antrum. Motilin receptor density in the antrum was not affected. Under control conditions, motilin induced a slowly developing tonic smooth muscle contraction. Five days post-inflammation, tonic contractions to motilin were reduced and preceded by a rapid initial contraction. Other kinases were recruited for the phosphorylation of myosin light chain (MLC) (a multi-functional MLC kinase), and for the inhibition of MLC phosphatase (Rho kinase in addition to protein kinase C) to mediate the motilin-induced contractions during inflammation. Colitis potentiated the cholinergic neural on-contractions in the antrum. This was associated with a hyper-reactivity to motilin and an increased muscle response to ACh.

CONCLUSIONS AND IMPLICATIONS

Colitis altered the course of the motilin-induced smooth muscle contraction in the antrum. This involved changes in the kinases phosphorylating MLC. Increased cholinergic excitability to motilin in the antrum may play a role in the pathogenesis of inflammation-associated gastric motility disorders.

Factors contributing to hospitalization for gastroparesis exacerbations

BACKGROUND

The clinical course of patients with gastroparesis is characterized by symptomatic exacerbations often necessitating hospitalization.

AIMS

To investigate precipitating factors leading to hospitalization for exacerbation of symptoms in patients with gastroparesis.

METHODS

This was a retrospective review of 103 admissions (63 patients) for gastroparesis exacerbation.

RESULTS

Etiologic categories for gastroparetic patients were diabetic (43%), idiopathic (39%), and post surgical (8%). Poor glycemic control was present in 36%, infection in 19% (12 urinary tract infections and two bacteremia), and noncompliance with or intolerance of, medications in six and 5% of patients, respectively. Fasting morning cortisol concentrations were \3 mcg/dl in 9%. Elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were seen in 34 of 65 (52%) and 11 of 50 patients (22%), respectively. No identifiable infection was found in 74 and 45% of patients with elevated ESR and elevated CRP, respectively. ESR and CRP were higher when patients were symptomatic necessitating hospitalization (26.2 +/- 6.6 mm/h and 1.6 +/- 1.0 mg/l) compared with when they were seen in outpatient follow-up and less symptomatic (10.3 +/- 2.9 mm/h and 0.3 +/- 0.1 mg/l; P = 0.0001 and P = 0.211, respectively).

CONCLUSIONS

Poor glycemic control, infection, noncompliance with/intolerance of medications, and, perhaps, adrenal insufficiency were contributory factors leading to hospitalizations of gastroparetic patients. Hospitalized patients with gastroparesis exacerbations had elevated ESR and CRP levels. Although many patients with elevated inflammatory markers had evidence of infection, some did not. Assessment of inflammatory markers may help indicate those gastroparetic patients in whom a search for infection should be undertaken.

Activation of human enteric neurons by supernatants of colonic biopsy specimens from patients with irritable bowel syndrome

BACKGROUND & AIMS

Pathological features in irritable bowel syndrome (IBS) include alterations in mucosal cell content and mediator release that might alter signaling to nearby submucosal neurons.

METHODS

Voltage sensitive dye imaging was used to record the effects of mediators, released from mucosal biopsies of IBS patients, on cell bodies of 1207 submucosal neurons from 76 human colonic tissue specimens. Supernatants, containing these mediators, were collected following incubation with colonic mucosal biopsies from 7 patients with diarrhea-predominant IBS (D-IBS), 4 with constipation-predominant IBS (C-IBS), and 4 healthy controls. Serotonin, histamine and tryptase concentrations in supernatants and lamina propria mast cell density were determined.

RESULTS

In contrast to controls, IBS supernatants significantly increased the rate of spike discharge in 58% of human submucosal neurons. Neurons that responded to IBS supernatant had a median spike frequency of 2.4 Hz compared to 0 Hz for control supernatants. Supernatants from C-IBS and D-IBS evoked similar spike discharge. The activation induced by IBS supernatants was inhibited by histamine receptor (H1-H3) antagonists, 5-HT3 receptor antagonist, and protease inhibition. Serotonin, histamine and tryptase levels in supernatants correlated with the spike discharge induced by the supernatants. Mast cells density as well as histamine and tryptase levels in supernatants were higher in IBS than in controls.

CONCLUSIONS

Mediators released from mucosal biopsies of IBS patients can activate human submucosal neurons. The activation required histamine, serotonin and proteases but was not associated with IBS subtype. Altered signaling between mucosa and the enteric nervous system might be involved in IBS pathogenesis.

Could gastric histology be a useful marker for making decision on Helicobacter pylori eradication therapy in patients with dyspepsia?

CONTEXT: It still remains an open debate whether Helicobacter pylori eradication is beneficial or not for the improvement of symptoms in functional dyspepsia. Differences in geographic distribution, the worldwide H. pylori genetic variability and the fact that the outcome of infection is strongly related to the virulence of the infecting strain are factors that might be driving ongoing controversies. OBJECTIVE: To study the correlation between gastric histology and H. pylori serology status in patients with dyspepsia. METHODS: This is a cross-sectional study where 40 consecutive dyspeptic patients (28 women and 12 men, mean age 48.5 years) with endoscopically normal stomachs were selected from the endoscopy unit at a university hospital in Recife, PE, Northeast of Brazil, between March 1998 and July 1999. Patients underwent gastric mucosal biopsy and serological tests (anti-Hp and anti-CagA antibodies). Gastric biopsies were examined using H-E and Giemsa stains and gastritis was classified and graded (mild, moderate or severe) according to "the updated Sydney System - Houston, 1994". RESULTS: Among 40 patients with dyspepsia the gastric histology revealed that about ¼ had moderate (25%) or severe (2.5%) gastritis. This subgroup of patients also had a greater positive frequency of anti-Hp (100% vs 41%; P = 0.0005) and anti-CagA (91% vs 58%; P = 0.09) antibodies when compared with those with normal histology (27.5%) or mild gastritis (45%). CONCLUSION: Since upper gastrointestinal endoscopy is part of the functional dyspepsia investigation and serology for anti-CagA antibody is not available in daily clinical practice, by biopsying gastric mucosa we would only be able to selectively apply H. pylori eradication therapy for those with histology that best correlate with virulent infecting strains (moderate or severe gastritis) - around ¼ of our study patients with dyspepsia.

The clinical course of postinfectious irritable bowel syndrome: a five-year follow-up study

OBJECTIVES

Irritable bowel syndrome (IBS) is a common disorder seen in general practice. Bacterial gastroenteritis has been known to be a risk factor for IBS. We investigated the clinical course, risk factors, and prognosis of postinfectious IBS (PI-IBS) 5 years after Shigella infection.

METHODS

We recruited 153 individuals and used a questionnaire to investigate their current bowel habits. We also looked for the presence of other functional bowel disorders (FBDs). The Shigella-exposed group consisted of hospital employees and medical students who experienced abdominal pain, diarrhea, or fever during the shigellosis outbreak and whose stool culture revealed Shigella sonnei. The control group consisted of age-matched and sex-matched subjects who corresponded fairly well with patients, considering that they were enrolled from the same hospital and were not infected.

RESULTS

Complete data were obtained from 119 individuals who were divided into the Shigella-exposed group (59) and the control group (60). In the Shigella-exposed group, 3 patients had IBS before infection (previous IBS) and 6 out of 13 cases of PI-IBS after 3 years showed persistent IBS after 5 years. Five out of 11 PI-IBS patients (45.5%, 2 excluded), 3 out of 6 previous IBS patients (50%) in the Shigella-exposed group, and 7 out of 11 previous IBS patients (63.6%) in the control group recovered after 5 years (P>0.05). Five cases in the Shigella-exposed group and 3 in the control group developed new cases of IBS after 5 years. The prevalence of PI-IBS after 5 years in the previous FBD groups was 63.6%, whereas the prevalence of PI-IBS without a history of FBDs was 36.4% (P<0.05). There were no significant differences among the other risk factors in each group.

CONCLUSIONS

About half of PI-IBS and previous IBS patients with or without infection recover over 5 years. Previous IBS and FBDs are risk factors of PI-IBS after 5 years. We suggest that our results support the understanding of the clinical course and prognosis of PI-IBS.

Transient receptor potential vanilloid-4 has a major role in visceral hypersensitivity symptoms

BACKGROUND & AIMS

The transient receptor potential vanilloid-4 (TRPV4) is an osmosensitive channel that responds to mechanical stimulation. We hypothesized that TRPV4 could be important in visceral nociception and in the development of hypersensitivity.

METHODS

TRPV4 expression was investigated by immunohistochemistry and reverse transcription-polymerase chain reaction. Calcium signaling and patch-clamp studies were performed in dorsal root ganglia (DRG) neurons validating the use of 4alphaPDD as a selective TRPV4 agonist. The effects of TRPV4 activation on visceral nociception were evaluated in mice that received intracolonically TRPV4 agonist (4 alpha-phorbol 12,13-didecanoate [4alphaPDD]) and in TRPV4-deficient mice in which abdominal muscle contractions in response to colorectal distention (CRD) were recorded. Intervertebral injections of TRPV4 or mismatch small interfering RNA (siRNA) were used to specifically down-regulate TRPV4 expression in sensory neurons and to investigate the role of TRPV4 in basal visceral nociception or in protease-activated receptor 2 (PAR(2)) activation-induced visceral hypersensitivity.

RESULTS

TRPV4 agonist 4alphaPDD specifically activated a cationic current and calcium influx in colonic projections of DRG neurons and caused dose-dependent visceral hypersensitivity. TRPV4-targeted but not mismatched siRNA intervertebral treatments were effective at reducing basal visceral nociception, as well as 4alphaPDD or PAR(2) agonist-induced hypersensitivity. Effects of the TRPV4 ligand were lost in TRPV4-deficient mice.

CONCLUSIONS

4alphaPDD selectively activates TRPV4 in sensory neurons projecting from the colon, and TRPV4 activation causes visceral hypersensitivity. TRPV4 activation is implicated in the nociceptive response to CRD in basal conditions and in PAR(2) agonist-induced hypersensitivity. These results suggest a pivotal role for TRPV4 in visceral nociception and hypersensitivity.

A rat model of chronic gastric sensorimotor dysfunction resulting from transient neonatal gastric irritation

BACKGROUND & AIMS

Although several pathophysiologic abnormalities have been noted in functional dyspepsia (FD), their pathogenesis is poorly understood. We hypothesized that chronic gastric hypersensitivity and gastric motor dysfunction seen in FD patients can be modeled in rats by transient gastric irritation during the neonatal period, a time of known neuronal vulnerability to long-term plasticity.

METHODS

Ten-day-old male rats received 0.2 mL 0.1% iodoacetamide (IA) in 2% sucrose daily by oral gavages for 6 days; controls received 2% sucrose. Rats in both groups were then followed to adulthood (8-10 weeks) at which point behavioral, visceromotor, and great splanchnic nerve responses to graded gastric balloon distention (GD; 20-80 mm Hg) and gastric motor function were tested.

RESULTS

IA-treated rats exhibited hypersensitivity to GD in a dose-dependent manner, as compared with the control group. The threshold of afferent nerve activation was lower and nerve responses to GD were significantly increased in IA-treated rats. Although IA-treated rats ingested food at a lower rate, gastric emptying was not significantly different between IA and control groups. However, gastric accommodation was significantly reduced in the IA group. No significant gastric pathology was seen in hypersensitive adult rats compared with controls.

CONCLUSIONS

These studies demonstrate that gastric irritation in the neonatal period can result in chronic gastric hypersensitivity and gastric motor dysfunction in adults even in the absence of significant detectable gastric pathology. Our results offer insight into the pathogenesis of chronic functional dyspepsia and provide a potential model for further study to this important clinical problem.

Updates on treatment of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a highly prevalent gastrointestinal disorder characterized by abdominal pain and discomfort in association with altered bowel habits. It is estimated to affect 10%-15% of the Western population, and has a large impact on quality of life and (in)direct healthcare costs. IBS is a multifactorial disorder involving dysregulation within the brain-gut axis, and it is frequently associated with gastrointestinal motor and sensory dysfunction, enteric and central nervous system irregularities, neuroimmune dysregulation, and post-infectious inflammation. As with other functional medical disorders, the treatment for IBS can be challenging. Conventional therapy for those with moderate to severe symptoms is largely unsatisfactory, and the development of new and effective drugs is made difficult by the complex pathogenesis, variety of symptoms, and lack of objective clinical findings that are the hallmark of this disorder. Fortunately, research advances over the past several decades have provided insight into potential mechanisms responsible for the pathogenesis of IBS, and have led to the development of several promising pharmaceutical agents. In recent years there has been much publicity over several of these new IBS medications (alosetron and tegaserod) because of their reported association with ischemic colitis and cardiovascular disease. While these agents remain available for use under restricted prescribing programs, this highlights the need for continued development of safe and effective medication for IBS. This article provides a physiologically-based overview of recently developed and frequently employed pharmaceutical agents used to treat IBS, and discusses some non-pharmaceutical options that may be beneficial in this disorder.