Defecation Symptoms in Relation to Stool Consistency Significantly Reflect the Dyssynergic Pattern in High-resolution Anorectal Manometry in Constipated Patients.

GOALS: To evaluate the usefulness of a 2-week patient-completed bowel habit and symptom diary as a screening tool for disordered rectoanal coordination (DRC). BACKGROUND: DRC is an important subgroup of chronic constipation that benefits from biofeedback treatment. Diagnosis of DRC requires a dyssynergic pattern (DP) of attempted defecation in high-resolution anorectal manometry (HRAM) and at least 1 other positive standardized examination, such as the balloon expulsion test or defecography. However, HRAM is generally limited to tertiary gastroenterology centres and finding tools for selecting patients for referral for further investigations would be of clinical value. STUDY: Retrospective data from HRAM and a 2-week patient-completed bowel habit and symptom diary from 99 chronically constipated patients were analyzed. RESULTS: Fifty-seven percent of the patients had a DP pattern during HRAM. In the DP group, 76% of bowel movements with loose or normal stool resulted in a sense of incomplete evacuation compared with 55% of the non-DP group ( P =0.004). Straining and sensation of incomplete evacuation with the loose stool were significantly more common in the DP group ( P =0.032). Hard stool was a discriminator for non-DP ( P =0.044). Multiple logistic regression including incomplete evacuation and normal stool predicted DP with a sensitivity of 82% and a specificity of 50%. CONCLUSIONS: The sensation of incomplete evacuation with loose or normal stool could be a potential discriminator in favor of DP in chronically constipated patients. The bowel habit and symptom diary may be a useful tool for stratifying constipated patients for further investigation of suspected DRC.

Acute psychological stress increases paracellular permeability and modulates immune activity in rectal mucosa of healthy volunteers.

BACKGROUND: Psychological stress and increased permeability are implicated as contributing factors in the initiation and worsening of gastrointestinal diseases. A link between stress and intestinal permeability has been shown in animal models as well as in human small intestine, but stress effects on the human colorectal mucosal barrier has not been reported. OBJECTIVE: To investigate the potential effects of acute psychological stress on colorectal mucosal barrier function and to explore stress-induced molecular events in the rectal mucosa under healthy conditions. METHODS: Endoscopic biopsies were taken from the rectosigmoid region of healthy volunteers, who had been subjected to dichotomous listening stress and after a control session, respectively. Paracellular and transcellular permeability were assessed in modified Ussing chambers. RNA expression (microarray technology confirmed by quantitative real-time polymerase chain reaction) and biological pathway analysis were used to investigate the local mucosal response to acute stress. RESULTS: Dichotomous listening stress induced a subjective and objective stress response, and significantly increased paracellular but not transcellular permeability. We also identified a stress-induced reduction in RNA expression of genes related to immune cell activation and maturation (CR2, CD20, TCLA1, BANK1, CD22, FDCSP), signaling molecules of homing of immune cells to the gut (chemokines: CCL21, CXCL13, and CCL19, and receptors: CCR7, CXCR5), and innate immunity (DUOX2). Eight of the 10 top down-regulated genes are directly involved in B cell activation, signaling and migration. The systemic stress response correlated positively with paracellular permeability and negatively with DUOX2 expression. CONCLUSION: Dichotomous listening stress increases paracellular permeability and modulates immune cell activity in the rectal mucosa. Further studies are warranted to identify the primary mechanisms of stress-mediated reduction of mucosal defensive activity and barrier dysfunction, and their potential implications for gastrointestinal disorders.

Elevated F-EDN correlates with mucosal eosinophil degranulation in patients with IBS-A possible association with microbiota?

Eosinophils have been linked to functional dyspepsia; however, less is known about their role in irritable bowel syndrome (IBS). This study tested the hypothesis of alterations in levels of fecal eosinophil-derived neurotoxin (F-EDN) and eosinophil density and degranulation within the colonic mucosa of IBS patients compared with healthy controls (HC). Colonic biopsies were collected from 37 IBS patients and 20 HC and analyzed for eosinophil numbers and local degranulation of eosinophil cationic protein (ECP) by histologic procedures. Fecal samples were collected for F-EDN and microbiota analysis. Differentiated 15HL-60 cells were used in vitro to investigate the direct effect of live bacteria on eosinophil activation measured by a colorimetric assay with o-phenylenediamine (OPD) substrate. We observed a higher number of eosinophils and increased extracellular ECP in the mucosa of IBS patients compared with HC. Moreover, F-EDN levels in IBS samples were elevated compared with HC and positively correlated to extracellular ECP. Metagenomic analysis showed significant correlations between bacterial composition and eosinophil measurements in both HC and IBS patients. In vitro experiments revealed an increased degranulation of 15HL-60 after stimulation with Salmonella typhimurium, Salmonella enterica, and Yersinia enterocolitica. To conclude, we could demonstrate alterations related to eosinophils in IBS, and, for the first time, a positive correlation between F-EDN levels and degranulated eosinophils in the colonic mucosa of IBS patients. Together our results suggest that eosinophils play a role in the pathophysiology of IBS and the mechanisms might be linked to an altered microbiota.

Altered interaction between enteric glial cells and mast cells in the colon of women with irritable bowel syndrome.

BACKGROUND: Enteric glial cells (EGC) and mast cells (MC) are intimately associated with gastrointestinal physiological functions. We aimed to investigate EGC-MC interaction in irritable bowel syndrome (IBS), a gut-brain disorder linked to increased intestinal permeability, and MC. METHODS: Parallel approaches were used to quantify EGC markers in colonic biopsies from healthy controls (HC) and patients with IBS. Data were correlated with MC, vasoactive intestinal polypeptide (VIP) and VIP receptors (VPAC1/VPAC2) expressions, and bacterial translocation through biopsies mounted in Ussing chambers. In addition, we investigated the effects of EGC mediators on colonic permeability and the pharmacological-induced responses of EGC and MC cell lines. KEY RESULTS: Immunofluorescence of IBS colonic mucosa, as well as Western blotting and ELISA of IBS biopsy lysates, revealed increased glial fibrillary intermediate filament (GFAP) expression, indicating EGC activation. Mucosal GFAP correlated with increased MC and VPAC1+ MC numbers and decreased VIP+ MC, which seemed to control bacterial translocation in HC. In the contrary, EGC activation in IBS correlated with less MC and VPAC1+ MC numbers, and more VIP+ MC. In vitro, MC and EGC cell lines showed intracellular calcium responses to each other's mediators. Furthermore, EGC mediators prevented VIP-induced MC degranulation, while MC mediators induced a reactive EGC phenotype. In Ussing chambers, EGC mediators decreased paracellular passage through healthy colonic biopsies. CONCLUSIONS & INFERENCES: Findings suggest the involvement of EGC and MC in the control of barrier function in the human colon and indicate a potential EGC-MC interaction that seems altered in IBS, with detrimental consequences to colonic permeability. Altogether, results suggest that imbalanced EGC-MC communication contributes to the pathophysiology of IBS.

Colonic paracellular permeability and circulating zonulin-related proteins.

OBJECTIVE: Irritable bowel syndrome (IBS) is a gut-brain disorder associated with increased gut permeability. Zonulin has been suggested to regulate the gut barrier and claimed to be pre-haptoglobin 2 (pre-HP2) and circulating zonulin is often used as a proxy for gastrointestinal permeability. This study investigated the correlation between colonic paracellular permeability and levels of circulating zonulin and pre-HP2. MATERIALS AND METHODS: Colonic biopsies from 32 patients with IBS and 15 healthy controls (HC) were used to measure permeability in Ussing chambers and levels of zonulin (Cusabio ELISA). Zonulin was also measured in blood samples from 40 HC, 78 patients with IBS and 20 patients with celiac disease (CeD), before and after a gluten-free diet. In addition, we verified HP genotype and circulating pre-HP2 using a monoclonal pre-HP2 antibody (Bio-Rad) by ELISA. RESULTS: Increased colonic paracellular permeability correlated positively with zonulin levels in IBS biopsies, but negatively with plasma zonulin. We found no agreement between circulating zonulin and pre-HP2. Genotyping revealed non-specificity of the zonulin kit, as all pre-HP2 non-producers presented detectable levels. Patients with CeD displayed higher pre-HP2 and zonulin levels compared to HC. A gluten-free diet in patients with CeD led to lower serum zonulin and pre-HP2 concentrations. CONCLUSIONS: Our study suggests that neither circulating zonulin nor pre-HP2 mirror colonic permeability. Our data corroborate previous reports showing the inability of the Cusabio zonulin kit to target zonulin and highlights that the results of studies using this kit must be re-examined with caution.

Increased Colonic Epithelial Permeability and Mucosal Eosinophilia in Ulcerative Colitis in Remission Compared With Irritable Bowel Syndrome and Health.

BACKGROUND: Barrier dysfunction is recognized as a pathogenic factor in ulcerative colitis (UC) and irritable bowel syndrome (IBS), but it is unclear to what extent the factors related to barrier dysfunction are disease-specific. The aim of this study was to compare these aspects in UC patients in remission, IBS patients, and healthy controls (HCs). METHODS: Colonic biopsies were collected from 13 patients with UC in remission, 15 patients with IBS-mixed, and 15 HCs. Ulcerative colitis patients had recently been treated for relapse, and biopsies were taken from earlier inflamed areas. Biopsies were mounted in Ussing chambers for measurements of intestinal paracellular permeability to 51chromium (Cr)-ethylenediaminetetraacetic acid (EDTA). In addition, biopsies were analyzed for mast cells and eosinophils by histological procedures, and plasma tumor necrosis factor (TNF)-α was assessed by ELISA. RESULTS: Ussing chamber experiments revealed an increased 51Cr-EDTA permeability in UC and IBS (P < 0.05). The 51Cr-EDTA permeability was higher in UC compared with IBS (P < 0.005). There were increased numbers of mucosal mast cells and eosinophils in UC and IBS and more eosinophils in UC compared with IBS (P < 0.05). Also, increased extracellular granule content was found in UC compared with HCs (P < 0.05). The 51Cr-EDTA permeability correlated significantly with eosinophils in all groups. Plasma TNF-α concentration was higher in UC compared with IBS and HCs (P < 0.0005). CONCLUSIONS: Results indicate a more permeable intestinal epithelium in inactive UC and IBS compared with HCs. Ulcerative colitis patients, even during remission, demonstrate a leakier barrier compared with IBS. Both eosinophil numbers and activation state might be involved in the increased barrier function seen in UC patients in remission.

Vasoactive Intestinal Polypeptide and Mast Cells Regulate Increased Passage of Colonic Bacteria in Patients With Irritable Bowel Syndrome.

BACKGROUND & AIMS: Irritable bowel syndrome (IBS) is associated with intestinal dysbiosis and symptoms of IBS develop following gastroenteritis. We aimed to study the passage of live bacteria through the colonic epithelium, and determine the role of mast cells (MCs) and vasoactive intestinal polypeptide (VIP) in barrier regulation in IBS and healthy individuals. METHODS: Colon biopsies from 32 women with IBS and 15 age-matched healthy women (controls) were mounted in Ussing chambers; we measured numbers of fluorescently labeled Escherichia coli HS and Salmonella typhimurium that passed through from the mucosal side to the serosal side of the tissue. Some biopsies were exposed to agents that block the VIP receptors (VPAC1 and VPAC2) or MCs. Levels of VIP and tryptase were measured in plasma and biopsy lysates. Number of MCs and MCs that express VIP or VIP receptors were quantified by immunofluorescence. Biopsies from an additional 5 patients with IBS and 4 controls were mounted in chambers and Salmonella were added; we studied passage routes through the epithelium by transmission electron microscopy and expression of tight junctions by confocal microscopy. RESULTS: In colon biopsies from patients with IBS, larger numbers of E coli HS and S typhimurium passed through the epithelium than in biopsies from controls (P < .0005). In transmission electron microscopy analyses, bacteria were found to cross the epithelium via only the transcellular route. Bacterial passage was reduced in biopsies from patients with IBS and controls after addition of antibodies against VPACs or ketotifen, which inhibits MCs. Plasma samples from patients with IBS had higher levels of VIP than plasma samples from controls. Biopsies from patients with IBS had higher levels of tryptase, larger numbers of MCs, and a higher percentage of MCs that express VPAC1 than biopsies from controls. In biopsies from patients with IBS, addition of Salmonella significantly reduced levels of occludin; subsequent addition of ketotifen significantly reversed this effect. CONCLUSIONS: We found that colonic epithelium tissues from patients with IBS have increased translocation of commensal and pathogenic live bacteria compared with controls. The mechanisms of increased translocation include MCs and VIP.

Positive Allosteric Modulator of GABA Lowers BOLD Responses in the Cingulate Cortex.

Knowledge about the neural underpinnings of the negative blood oxygen level dependent (BOLD) responses in functional magnetic resonance imaging (fMRI) is still limited. We hypothesized that pharmacological GABAergic modulation attenuates BOLD responses, and that blood concentrations of a positive allosteric modulator of GABA correlate inversely with BOLD responses in the cingulate cortex. We investigated whether or not pure task-related negative BOLD responses were co-localized with pharmacologically modulated BOLD responses. Twenty healthy adults received either 5 mg diazepam or placebo in a double blind, randomized design. During fMRI the subjects performed a working memory task. Results showed that BOLD responses in the cingulate cortex were inversely correlated with diazepam blood concentrations; that is, the higher the blood diazepam concentration, the lower the BOLD response. This inverse correlation was most pronounced in the pregenual anterior cingulate cortex and the anterior mid-cingulate cortex. For subjects with diazepam plasma concentration > 0.1 mg/L we observed negative BOLD responses with respect to fixation baseline. There was minor overlap between cingulate regions with task-related negative BOLD responses and regions where the BOLD responses were inversely correlated with diazepam concentration. We interpret that the inverse correlation between the BOLD response and diazepam was caused by GABA-related neural inhibition. Thus, this study supports the hypothesis that GABA attenuates BOLD responses in fMRI. The minimal overlap between task-related negative BOLD responses and responses attenuated by diazepam suggests that these responses might be caused by different mechanisms.

Combination therapy with biofeedback, loperamide, and stool-bulking agents is effective for the treatment of fecal incontinence in women - a randomized controlled trial.

OBJECTIVE: Biofeedback and medical treatments have been extensively used for moderate fecal incontinence (FI). There is limited data comparing and combining these two treatments. The objective of this study was to evaluate the effect of biofeedback and medical treatments, separately and in combination. MATERIAL AND METHODS: Sixty-four consecutive female patients, referred to a tertiary centre for FI, were included. The patients were randomized to start with either biofeedback (4-6 months) or medical treatment with loperamide and stool-bulking agents (2 months). Both groups continued with a combination of treatments, i.e. medical treatment was added to biofeedback and vice versa. A two-week prospective bowel symptom diary and anorectal physiology were evaluated at baseline, after single- and combination treatments. RESULTS: Fifty-seven patients completed the study. Median number of leakage episodes during two weeks decreased from 6 to 3 (p < 0.0001) from baseline to completion. The patients showed a significant (1) decrease in number of leakages without forewarning (p = 0.04); (2) decrease in number of stools with urgency (p = 0.001); (3) decrease in number of loose stool consistency; and (4) an increase in rectal sensory thresholds, both for maximum tolerable rectal pressure and first sensation (<0.01). The combination treatment was superior to both single treatments in terms of symptoms and functions. There was no significant difference between the two groups at any time point. CONCLUSIONS: The combination therapy with biofeedback and medical treatment is effective for symptom relief in FI. The symptom improvement was associated with improved fecal consistency, reduced urgency, and increased rectal sensory thresholds.

Brain responses to visceral stimuli reflect visceral sensitivity thresholds in patients with irritable bowel syndrome.

BACKGROUND & AIMS: Only a fraction of patients with irritable bowel syndrome (IBS) have increased perceptual sensitivity to rectal distension, indicating differences in processing and/or modulation of visceral afferent signals. We investigated the brain mechanisms of these perceptual differences. METHODS: We analyzed data from 44 women with IBS and 20 female healthy subjects (controls). IBS symptom severity was determined by a severity scoring system. Anxiety and depression symptoms were assessed using the hospital anxiety and depression score. Blood oxygen level-dependent signals were measured by functional magnetic resonance imaging during expectation and delivery of high (45 mmHg) and low (15 mmHg) intensity rectal distensions. Perception thresholds to rectal distension were determined in the scanner. Brain imaging data were compared among 18 normosensitive and 15 hypersensitive patients with IBS and 18 controls. Results were reported significant if peak P-values were ≤.05, with family-wise error correction in regions of interest. RESULTS: The subgroups of patients with IBS were similar in age, symptom duration, psychological symptoms, and IBS symptom severity. Although brain responses to distension were similar between normosensitive patients and controls, hypersensitive patients with IBS had greater activation of insula and reduced deactivation in pregenual anterior cingulate cortex during noxious rectal distensions, compared to controls and normosensitive patients with IBS. During expectation of rectal distension, normosensitive patients with IBS had more activation in right hippocampus than controls. CONCLUSIONS: Despite similarities in symptoms, hyper- and normosensitive patients with IBS differ in cerebral responses to standardized rectal distensions and their expectation, consistent with differences in ascending visceral afferent input.

Prospective diary evaluation of unexplained abdominal pain and bowel dysfunction: a population-based colonoscopy study.

INTRODUCTION: Diagnostic criteria for irritable bowel syndrome (IBS) have not been validated by prospective symptom diary. We investigated the bowel patterns in community subjects with and without non-organic abdominal pain, and compared the symptoms with subjects fulfilling the Rome II criteria (IBS). METHODS: From the Swedish population register, a random sample completed an abdominal symptom questionnaire. Responders were subsequently invited for a clinical evaluation and offered a colonoscopy regardless of whether they had abdominal symptoms or not. A total of 268 subjects underwent colonoscopy, clinical evaluation by gastroenterologist, laboratory investigations, and completed the Rome questionnaire and prospective gastrointestinal (GI) symptom diaries for 1 week. Twenty-three subjects of 268 were excluded due to organic GI disease. RESULTS: Subjects recorded 2,194 bowel movements and 370 abdominal pain episodes on 1,504 days. Subjects with pain in the diary (n = 81) had higher stool frequency (P = 0.01), more urgency (P = 0.0002), feelings of incomplete evacuation (P = 0.0002), nausea (P = 0.0009), and abdominal bloating (P = 0.0005) than subjects without pain (n = 151). Twenty-eight subjects (12%) fulfilled the Rome II criteria for IBS. Together, they had 96 pain episodes but only 4% were improved by defecation; 29% of the pain episodes started or worsened after a meal. Subjects with IBS and other subjects with non-organic abdominal pain (n = 64) exhibited no differences in terms of the proportions of pain episodes improved by defecation, bloating, stool frequency, consistency, or defecatory symptoms. CONCLUSIONS: Current criteria for IBS that rely on recall of the relationship between abdominal pain and bowel disturbance may overcall this association when measured prospectively.

Assessment of normal bowel habits in the general adult population: the Popcol study.

OBJECTIVE: Defining normal stool habit is important when evaluating diarrhoea or constipation, but common confounders such as irritable bowel syndrome (IBS) or the intake of medications with gastrointestinal side effects have not been considered in earlier population based studies defining what is normal. We hypothesized that the exclusion of subjects with common confounders would help to better understand what are "normal bowel habits". We aimed to prospectively study bowel habits in a carefully studied random sample of the general population. MATERIAL AND METHODS: Two hundred and sixty-eight randomly selected subjects between 18 and 70 years completed symptom diaries for one week and were clinically evaluated by a gastroenterologist. They also had a colonoscopy and laboratory investigations to exclude organic disease. RESULTS: One hundred and twenty-four subjects had no organic gastrointestinal abnormality, IBS, or relevant medication; 98% of them had between three stools per day and three per week. Seventy-seven percent of all stools were normal, 12% hard, and 10% loose in consistency. Urgency was reported by 36%; straining by 47% and incomplete defecation by 46%. After the exclusion of subjects with organic abnormalities, women had significantly more symptoms than men in terms of abdominal pain, bloating, constipation, urgency, and feeling of incomplete evacuation but these gender differences disappeared after excluding subjects with IBS. CONCLUSIONS: This study confirms that normal stool frequency is between three per week and three per day. We could not demonstrate any gender or age differences in terms of stool frequency, defecatory symptoms or abdominal bloating. Some degree of urgency, straining, and incomplete evacuation should be considered normal.

Subgroups of irritable bowel syndrome: a new approach.

OBJECTIVES: The newly revised Rome criteria for the definition of irritable bowel syndrome (IBS), derived from the consensus of experts in the field, were developed in order to identify subgroups of IBS patients for research. The criteria have, to our knowledge, never been validated. Both when trying to include IBS patients in studies and in clinical practice we found it difficult to apply the Rome 2 supportive criteria. AIM: To study the variation of stool consistency and defecatory symptoms in IBS patients prospectively with diary cards and to validate the Rome 2 supportive criteria. METHODS: Sixty IBS patients, included by interview according to the Rome 1 criteria, recorded their bowel symptoms on diary cards over 40 days. Four subgroups were found, characterised by loose-stool-predominant, hard-stool-predominant, alternating stool consistency, and loose stools only. Urgency, straining and feeling of incomplete evacuation occurred in all but seven individuals, irrespective of subgroup. RESULTS: The Rome 2 criteria could subclassify seven patients into diarrhoea-predominant IBS based on stool consistency and absence of straining and could subclassify no patients into constipation-predominant IBS, as urge was present in nearly all patients. Fifty-three patients could not be classified according to the Rome 2 criteria, as they had defecatory symptoms of all kinds. CONCLUSION: As the Rome 2 supportive criteria use the presence or absence of specific defecatory symptoms as an instrument for categorising IBS patients into diarrhoea- and constipation-predominant subgroups, these criteria could not be used for the majority of IBS patients in this study and should be reconsidered.

Rectal pressure response to a meal in patients with high spinal cord injury.

OBJECTIVES: To determine whether there is a postprandial increase of rectal pressure in patients with spinal cord injury (SCI) and to compare their rectal pressures with those of healthy volunteers. DESIGN: A before-after trial comparing SCI and control subjects. SETTING: Patients were recruited from the register of an SCI unit at a rehabilitation medicine department, and the study took place at the university hospital laboratory in Sweden. PARTICIPANTS: Ten patients with high traumatic SCI and 9 healthy volunteers. Eight patients had a lesion above level T5. INTERVENTION: Continuous anorectal manometry was performed. Rectal activity was calculated before and at regular time intervals after a 1000-cal test meal. MAIN OUTCOME MEASURE: Rectal activity measured as area under the pressure curve. RESULTS: There was a significant increase in rectal activity of 46% after 10 minutes in the patients but of 72% after 5 minutes in the volunteers. There was no difference in fasting rectal activity, but patients had a stronger mean rectal postprandial response during 60 minutes compared with volunteers. CONCLUSIONS: These results support the theory that the colonic response to food is preserved in patients with high SCI.