Post-infectious irritable bowel syndrome. Curr Gastroenterol Rep. 2007;9:378-384. [PMID: 17991338 DOI: 10.1007/s11894-007-0046-8]

Cow's Milk Protein Allergy in Infancy: A Risk Factor for Functional Gastrointestinal Disorders in Children?

The role and prevalence of cow's milk protein allergy (CMA) in functional gastrointestinal disorders remains unclear. The aim of this review is to update knowledge on the relationship between CMA and functional abdominal pain disorders (FAPDs) in children. Cochrane Database and Pubmed were searched from inception using general and specific terms for CMA and functional gastrointestinal disorders. CMA is reported as a predisposing or coexisting factor in a wide range of functional gastrointestinal disorders in infants and children. Pathogenesis of both conditions is complex and multiple mechanisms including dysmotility and hypersensitivity might contribute to the clinical manifestations. Data supporting the possible role of food allergies in the pathogenesis of FAPDs are limited. CMA may predispose to early life inflammation and visceral hypersensitivity, which in turn might manifest as FAPDs. The diagnosis of either CMA or FAPDs and distinction between them is challenging because of nonspecific and overlapping symptoms. Lack of accurate allergy tests in non-IgE (immunoglobulin E) mediated cases is also problematic. Oral food challenge, following an elimination diet, should be performed to diagnose a suspected non-IgE CMA allergy in children with FAPDs. In the management of FAPDs, an elimination diet should be considered for a limited period to verify if the symptoms improve or resolve.

Association between gastrointestinal motility and macrophage/mast cell distribution in mice during the healing stage after DSS‑induced colitis

Irritable bowel syndrome (IBS) frequently occurs after infectious colitis or inflammatory bowel disease in patients with complete remission. This suggests that post‑inflammation‑associated factors may serve a role in the pathophysiology of IBS; however, the mechanism responsible remains unclear. In the present study, the involvement of macrophages and mast cells in alteration of gastrointestinal (GI) motility was investigated in mice in the remission stage after acute colitis. C57BL/6 mice were administered 2% dextran sulfate sodium in drinking water for 5 days and their intestinal tissues were investigated at intervals for up to 24 weeks. Expression of the mannose receptor (MR) and tryptase was examined by immunohistochemistry, and the GI transit time (GITT) was measured by administration of carmine red solution. A minimal degree of inflammatory cell infiltration persisted in the colon and also the small intestine of mice in remission after colitis and the GITT was significantly shorter. The number of muscularis MR‑positive macrophages was significantly increased in the small intestine of mice in remission after colitis and negatively correlated with GITT. Furthermore, results indicated that the number of muscularis tryptase‑positive mast cells was significantly increased throughout the intestine of mice during the healing process after colitis and was positively correlated with GITT. The present findings suggested an increased number of macrophages and/or mast cells in the intestinal muscular layer may be associated with the pathophysiology of GI dysmotility after colitis.

Allergic Proctocolitis Is a Risk Factor for Functional Gastrointestinal Disorders in Children

OBJECTIVE

To test the hypothesis that allergic proctocolitis, a cause of self-limiting rectal bleeding in infants, can predispose to the development of functional gastrointestinal disorders (FGIDs) later in childhood.

STUDY DESIGN

We studied a cohort of 80 consecutive patients diagnosed with allergic proctocolitis. Their sibling or matched children presenting to the same hospital for minor trauma served as controls. Parents of the patients with allergic proctocolitis and controls participated in a telephone interview every 12 months until the child was at least 4 years old. At that time, they were asked to complete the parental Questionnaire on Pediatric Gastrointestinal Symptoms, Rome III version.

RESULTS

Sixteen of the 160 subjects (10.0%) included in the study met the Rome III criteria for FGIDs. Among the 80 patients with allergic proctocolitis, 12 (15.0%) reported FGIDs, compared with 4 of 80 (5.0%) controls (P = .035). After adjustment for age and sex, the OR for FGIDs in allergic proctocolitis group was 4.39 (95% CI, 1.03-18.68). FGIDs were significantly associated with iron deficiency anemia, duration of hematochezia, and younger age at presentation. In a multivariate analysis, only the duration of hematochezia was significantly associated with the development of FGIDs (OR, 3.14; 95% CI,1.72-5.74).

CONCLUSIONS

We have identified allergic proctocolitis as a new risk factor for the development of FGIDs in children. Our data suggest that not only infection, but also a transient early-life allergic inflammatory trigger may induce persistent digestive symptoms, supporting the existence of "postinflammatory" FGIDs.

High Prevalence of Nausea among School Children in Latin America

OBJECTIVES

To evaluate the prevalence of nausea and its association with functional gastrointestinal disorders (FGIDs) in a large-scale, population-based study of Latin American school children.

STUDY DESIGN

This cross-sectional study collected data from children in 3 Latin American countries. A Spanish version of the Questionnaire on Pediatric Gastrointestinal Symptoms-Rome III Version (QPGS-III) was administered to school children in Central and South America. Subjects were classified into FGIDs based on Rome criteria (QPGS-III). Students from 4 public and 4 private schools in the countries of El Salvador, Panama, and Ecuador participated in this epidemiologic study.

RESULTS

A total of 1137 school children with mean age 11.5 (SD 1.9, range 8-15) years completed the QPGS-III (El Salvador n = 399; Panama n = 321; Ecuador n = 417). Nausea was present in 15.9% of all school children. Two hundred sixty-eight (24%) children met criteria for at least 1 FGID. Nausea was significantly more common in children with FGIDs compared with those without: El Salvador 38% vs 15% (P < .001); Panama 22% vs 7% (P < .001); Ecuador 25% vs 13% (P = .004). Among children with FGIDs, those with functional constipation had a high prevalence of nausea. Nausea was significantly more common in girls and children attending private schools.

CONCLUSIONS

Nausea is commonly present in Latin American school children. FGIDs are frequently associated with nausea.

Tropical sprue in 2014: the new face of an old disease

Tropical sprue (TS), once known to be a common cause of malabsorption syndrome (MAS) in India and other tropical countries, is believed to be uncommon currently in spite of contrary evidence. Several recent studies from India showed TS to be the commonest cause of sporadic MAS in Indian adults. TS is diagnosed in patients presenting with suggestive clinical presentation, which cannot be explained by another cause of MAS and investigations revealing malabsorption of two unrelated substances, abnormal small-intestinal mucosal histology, which responds to treatment with antibiotics such as tetracycline and folic acid. There is substantial overlap between TS and postinfectious irritable bowel syndrome. There have been several advances in epidemiology, pathogenesis, and diagnosis of TS, hitherto an enigmatic condition.

Brain and gut interactions in irritable bowel syndrome: new paradigms and new understandings

Irritable bowel syndrome (IBS) is characterized by abdominal pain and altered bowel habits. Visceral hypersensitivity is believed to be a key underlying mechanism that causes pain. There is evidence that interactions within the brain and gut axis (BGA), that involves both the afferent-ascending and the efferent-descending pathways, as well as the somatosensory cortex, insula, amygdala, anterior cingulate cortex, and hippocampus, are deranged in IBS showing both the activation and inactivation. Clinical manifestations of IBS such as pain, altered gut motility, and psychological dysfunction may each be explained, in part, through the changes in the BGA, but there is conflicting information, and its precise role is not fully understood. A better understanding of the BGA may shed more knowledge regarding the pathophysiology of IBS that in turn may lead to the discovery of novel therapies for this common disorder.

Inhibitory effects of SKI3246, the rhizome extract of Atractylodes japonica, on visceral hypersensitivity in experimental irritable bowel syndrome rat models

We evaluated the effect of SKI3246, the 50% ethanol extract of the rhizome of Atractylodes japonica, on visceral hypersensitivity, which is a major characteristic feature of IBS. We used various rat models of visceral hypersensitivity to assess the visceral pain responses to colorectal distension (CRD) in comparison with conventional IBS treatments. Oral administration of SKI3246 dose-dependently and significantly attenuated the abdominal withdrawal reflex (AWR) score in a model of acetic acid-induced visceral hypersensitivity. We also found that it reduced the number of abdominal contractions in response to CRD in a model of 2,4,6-trinitrobenzenesulfonic acid-induced visceral hypersensitivity, which was comparable to ramosetron or alosetron. Furthermore, treatment with SKI3246 also increased the pain threshold and abolished the elevated AWR scores to CRD in a rat model of neonatal maternal separation. We presumed that the modulation of the NK2 receptor is involved in the inhibitory activity of SKI3246 on the basis that it significantly inhibited the contraction of the distal colonic muscle induced by neurokinin A, the NK2 receptor agonist. The present results indicate that SKI3246 has the potential to be an effective therapeutic agent for IBS, especially insofar as it can relieve visceral hypersensitivity.

Pathogenesis of irritable bowel syndrome--review regarding associated infection and immune activation

There is increasing evidence regarding the role of immune activation in the etiology of irritable bowel syndrome (IBS), which has been mainly been shown in studies investigating mechanisms of postinfectious IBS (PI-IBS). Exposure to intestinal infection induces persistent low-grade systemic and mucosal inflammation, which is characterized by an altered population of circulating cells, mucosal infiltration of immune cells and increased production of various cytokines in IBS patients. Recent studies have also indicated an increased innate immune response in these patients by evaluating expression and activation of Toll-like receptors (TLRs). These findings suggest that immune activation may play a crucial role in the pathogenesis of IBS. In addition, psychological stress has been reported to be one of the factors that induces immune activation. However, it remains unknown whether immune activation in IBS patients is largely dependent on infectious gastroenteritis and/or psychological stress. Additional studies are necessary to understand the precise mechanism of immune activation and its relationship to the development of IBS.

GeoSentinel surveillance of illness in returned travelers, 2007-2011

BACKGROUND

International travel continues to increase, particularly to Asia and Africa. Clinicians are increasingly likely to be consulted for advice before travel or by ill returned travelers.

OBJECTIVE

To describe typical diseases in returned travelers according to region, travel reason, and patient demographic characteristics; describe the pattern of low-frequency travel-associated diseases; and refine key messages for care before and after travel.

DESIGN

Descriptive, using GeoSentinel records.

SETTING

53 tropical or travel disease units in 24 countries.

PATIENTS

42 173 ill returned travelers seen between 2007 and 2011.

MEASUREMENTS

Frequencies of demographic characteristics, regions visited, and illnesses reported.

RESULTS

Asia (32.6%) and sub-Saharan Africa (26.7%) were the most common regions where illnesses were acquired. Three quarters of travel-related illness was due to gastrointestinal (34.0%), febrile (23.3%), and dermatologic (19.5%) diseases. Only 40.5% of all ill travelers reported pretravel medical visits. The relative frequency of many diseases varied with both travel destination and reason for travel, with travelers visiting friends and relatives in their country of origin having both a disproportionately high burden of serious febrile illness and very low rates of advice before travel (18.3%). Life-threatening diseases, such as Plasmodium falciparum malaria, melioidosis, and African trypanosomiasis, were reported.

LIMITATIONS

Sentinel surveillance data collected by specialist clinics do not reflect healthy returning travelers or those with mild or self-limited illness. Data cannot be used to infer quantitative risk for illness.

CONCLUSION

Many illnesses may have been preventable with appropriate advice, chemoprophylaxis, or vaccination. Clinicians can use these 5-year GeoSentinel data to help tailor more efficient pretravel preparation strategies and evaluate possible differential diagnoses of ill returned travelers according to destination and reason for travel.

PRIMARY FUNDING SOURCE

Centers for Disease Control and Prevention.

Luminal hypertonicity and acidity modulate colorectal afferents and induce persistent visceral hypersensitivity

Carbohydrate malabsorption such as in lactose intolerance or enteric infection causes symptoms that include abdominal pain. Because this digestive disorder increases intracolonic osmolarity and acidity by accumulation of undigested carbohydrates and fermented products, we tested whether these two factors (hypertonicity and acidity) would modulate colorectal afferents in association with colorectal nociception and hypersensitivity. In mouse colorectum-pelvic nerve preparations in vitro, afferent activities were monitored after application of acidic hypertonic saline (AHS; pH 6.0, 800 mosM). In other experiments, AHS was instilled intracolonically to mice and behavioral responses to colorectal distension (CRD) measured. Application of AHS in vitro excited 80% of serosal and 42% of mechanically-insensitive colorectal afferents (MIAs), sensitizing a proportion of MIAs to become mechanically sensitive and reversibly inhibiting stretch-sensitive afferents. Acute intracolonic AHS significantly increased expression of the neuronal activation marker pERK in colon sensory neurons and augmented noxious CRD-induced behavioral responses. After three consecutive daily intracolonic AHS treatments, mice were hypersensitive to CRD 4-15 days after the first treatment. In complementary single fiber recordings in vitro, the proportion of serosal class afferents increased at day 4; the proportion of MIAs decreased, and muscular class stretch-sensitive afferents were sensitized at days 11-15 in mice receiving AHS. These results indicate that luminal hypertonicity and acidity, two outcomes of carbohydrate malabsorption, can induce colorectal hypersensitivity to distension by altering the excitability and relative proportions of colorectal afferents, suggesting the potential involvement of these factors in the development of abdominal pain.

Relationship among food intolerance, severity of symptoms and the number of mast cells in the ileocecal junction in patients with diarrhea-predominant irritable bowel syndrome

AIM: To analyze the relationship among food intolerance, severity of symptoms and the number of mucosal mast cells (MCs) in the ileocecal junction (ICJ) in patients with diarrhea-predominant irritable bowel syndrome (D-IBS), and to explore the influence of food intolerance on the pathogenesis of D-IBS.

METHODS: Twenty-two patients with D-IBS fulfilling the Rome III criteria and 21 asymptomatic healthy controls underwent colonoscopy in which two adjacent biopsy samples were taken from the ICJ. Mucosal MCs were detected by toluidine blue staining. The Food Intolerance Questionnaire was used to evaluate the perceived food intolerance status of D-IBS patients and controls. The Functional Bowel Disorder Severity Index (FBDSI) and IBS Symptom Severity Scale (IBS-SSS) were used to evaluate the severity of symptoms in D-IBS patients. The relationship among the scores of FBDSI and IBS-SSS, the number of MCs and the scores of food intolerance in D-IBS patients was analyzed.

RESULTS: The number of mucosal MCs in the ICJ was significantly higher in patients with D-IBS than in controls (4.68 ± 0.55/HP vs 1.33 ± 0.54/HP, P < 0.001). Compared to controls, perceived FI was more frequent in patients with D-IBS (P < 0.05). The scores of FBDSI and IBS-SSS were positively correlated with that of food intolerance in D-IBS patients (FBDSI: r = 0.992, P < 0.001; IBS-SSS: r = 0.970, P < 0.001), and with the number of mucosal MCs in the ICJ (FBDSI: r = 0.957, P < 0.001; IBS-SSS: r = 0.985, P < 0.001). The scores of food intolerance in D-IBS patients were positively correlated with the number of mucosal MCs in the ICJ (r = 0.964, P < 0.001). The number of mucosal MCs in the ICJ were significantly higher in healthy subjects with self-reported food intolerance than in those without food intolerance (P < 0.05).

CONCLUSION: The symptoms of D-IBS are positively correlated with increased number of enteric mucosal MCs which might be caused by food antigen. Food intolerance is more frequent in D-IBS patients than in controls. D-IBS symptoms may be caused or exacerbated by food intolerance.

Protease activated receptor 4 status of mast cells in post infectious irritable bowel syndrome

BACKGROUND

Growing evidence suggests that protease activated receptors (PARs) are mediators of persistent neuropathic pain, but their possible function as mediators in patients with post infectious irritable bowel syndrome (PI-IBS) remains to be further explored. This article aims to investigate the expression of PAR(2) and PAR(4) in the colonic mucosa of patients with PI-IBS, focusing on correlation with mast cell activation status.

METHODS

A total of 17 normal controls and 23 patients with PI-IBS volunteered the study. The expression and localization of PAR(2) and PAR(4) were investigated by RT-PCR and immunohistochemistry, and the expression of PAR(2) and PAR(4) in the mast cells was examined using double-immunofluorescence staining.

KEY RESULTS

The immunohistochemical study revealed that epithelial and submucosal cells showed immunoreactivity for both PAR(2) and PAR(4). Protease activated receptor 4 mRNA expression and immunoreactivity were down-regulated in PI-IBS compared with the control group. Specifically, a reduced immunoreactivity for PAR(4) was observed in mast cells of PI-IBS compared with normal controls, whereas there are no significant differences shown in PAR(2) between the PI-IBS and the control group. It is also found that the PAR(4) immunoreactivity decreases, while the activity of mast cells increases in PI-IBS rather than normal controls.

CONCLUSIONS & INFERENCES

This study outlines the down-regulation of PAR(4) in the mast cells of PI-IBS. It could be of considerable interests in understanding the mechanisms involved in the persistent colonic hypersensitivity and their potential role as therapeutic targets for PI-IBS.

Soluble mediators released from PI-IBS patients' colon induced alteration of mast cell: involvement of reactive oxygen species

BACKGROUND

Growing evidence suggests that patients with post-infectious irritable bowel syndrome (PI-IBS) have increased mast cell activation, and that mucosal soluble mediators are involved in the pathophysiology of visceral hyperalgesia. In addition, previous findings show that reactive oxygen species (ROS) and protease-activated receptors (PARs) are mediators of persistent hyperalgesia.

AIMS

This article aims to investigate: (1) the ability of soluble factors from colonic biopsies to active peritoneal mast cells (PMCs) in vitro; (2) whether the effects of PMCs degranulation induced by soluble mediators are related to PARs activation; and (3) the ability of phenyl N-tert-butylnitrone (PBN), a ROS scavenger, to modify these alterations.

METHODS

Supernatant (SUP) from colonic biopsies was collected and applied to PMCs for 12 h. Activation of PMCs was evaluated. The expression of PAR(2) in PMCs was examined by RT-PCR and double-immunofluorescence staining. PBN (10 mM) treatment was administered, then previous alterations were observed again.

RESULTS

Stimulation with SUP of PI-IBS led to an increase in activation of PMCs. PAR(2)mRNA expression was significantly increased in PMCs induced by SUP of PI-IBS compared to healthy subjects. After being treated by PBN, the SUP-induced enhancement of PMCs activities could be weakened, and PAR(2)mRNA expression was significantly decreased. A similar result of immunoreactivity for PAR(2) was observed in PMCs.

CONCLUSIONS

The study shows that ROS scavenger reverses the SUP of PI-IBS-induced enhancement of PMCs activities, and that these effects may be related to activation of PAR(2). These findings might pave the way to new therapeutic targets in PI-IBS.

New insight in the pathogenesis of functional gastrointestinal disorders: association between genetics and colonic transit

Genome wide association studies and meta-analyses identified risk factors related to epithelial integrity of the intestinal barrier, innate immune responses and autophagy in inflammatory bowel disorder (IBD) and celiac disease. Irritable bowel syndrome (IBS), the most common functional gastrointestinal disorder (FGID), coexists and shares common, although milder, features with IBD and celiac disease. Although our knowledge on genetic variability in IBS symptom generation is very limited, smaller scale studies attempt to provide insight in the mechanisms underlying IBS. Camilleri et al. identified associations for susceptibility loci in inflammatory and epithelial barrier genes with colonic transit in lower FGID. Their report is the first descriptive study to assess potential genetic factors involved in motor function. Further exploration of genetic variation in IBS will be crucial to unravel its' pathogenesis.

New insights into visceral hypersensitivity--clinical implications in IBS

A subset of patients with IBS have visceral hypersensitivity and/or somatic hypersensitivity. Visceral hypersensitivity might have use as a clinical marker of IBS and could account for symptoms of urgency for bowel movements, bloating and abdominal pain. The mechanisms that lead to chronic visceral hypersensitivity in patients who have IBS are unclear. However, several working models may be considered, including: nociceptive input from the colon that leads to hypersensitivity; increased intestinal permeability that induces a visceral nociceptive drive; and alterations in the expression of microRNAs in gastrointestinal tissue that might be delivered via blood microvesicles to other target organs, such as the peripheral and/or central nervous system. As such, the chronic visceral hypersensitivity that is present in a subset of patients with IBS might be maintained by both peripheral and central phenomena. The theories underlying the development of chronic visceral hypersensitivity in patients with IBS are supported by findings from new animal models in which hypersensitivity follows transient inflammation of the colon. The presence of somatic hypersensitivity and an alteration in the neuroendocrine system in some patients who have IBS suggests that multisystemic factors are involved in the overall disorder. Thus, IBS is similar to other chronic pain disorders, such as fibromyalgia, chronic regional pain disorder and temporomandibular joint disorder, as chronic nociceptive mechanisms are activated in all of these disorders.

Cow's-milk allergy is a risk factor for the development of FGIDs in children

OBJECTIVES

Functional gastrointestinal disorders (FGIDs) are common in children. Their pathogenesis remains unknown and is most likely multifactorial. We hypothesized that noninfectious causes of inflammation affecting the gastrointestinal (GI) tract early in life, such as cow's-milk allergy (CMA), can predispose to the development of FGIDs later in childhood.

PATIENTS AND METHODS

Case-control study. Subjects were patients between 4 and 18 years diagnosed with CMA in the first year of life at Children's Memorial Hospital in Chicago, IL, between January 2000 and June 2009. Diagnosis of CMA was based on history and clinical findings. Siblings 4 to 18 years of age without a history of CMA were selected as controls. Cases completed the parental form of the Pediatric Gastrointestinal Symptoms Rome III version questionnaire to assess for GI symptoms.

RESULTS

Fifty-two subjects (mean age 8.1 ± 4.48 years, 62% girls) and 53 controls (mean age 9.7 ± 4.20 years, 55% girls) participated in the study. Twenty-three of 52 subjects (44.2%) reported GI symptoms that included abdominal pain, constipation, or diarrhea compared with 11 of 53 controls (20.75%) (odds ratio 3.03, P = 0.01). Abdominal pain was significantly more common in cases (16/52, 30.8%) versus controls (5/53, 9.43%) (odds ratio 4.27 [1.43-12.7]) (χ² = 7.47, P = 0.01). Abnormal stool habits were more common in cases (15/52, 28.8%) versus controls (7/53, 13.2%), but the difference was not statistically significant. Ten of 52 subjects (19.2%) met the Questionnaire on Pediatric Gastrointestinal Symptoms Rome III version criteria for diagnosis of an FGID (7 irritable bowel syndrome, 2 functional dyspepsia, 1 functional abdominal pain), whereas none in the control group did.

CONCLUSIONS

CMA constitutes a risk factor for the development of FGIDs in children.

Travel and travelers' diarrhea in patients with irritable bowel syndrome

This study evaluated occurrence of travel and travelers' diarrhea in patients with irritable bowel syndrome (IBS). A survey was mailed to 591 patients of a clinical practice who had IBS. Based on survey responses, patients were categorized as having IBS, post-infectious IBS (PI-IBS), unclassified functional bowel disorder (UFBD), or post-infectious UFBD (PI-UFBD). Of 201 persons who returned questionnaires meeting inclusion criteria, 57.7%, 11.4%, 24.9%, and 6.0% had IBS, UFBD, PI-IBS, and PI-UFBD, respectively. Travel during six months before illness onset was more common in patients with PI-IBS or PI-UFBD than in persons with idiopathic IBS or UFBD (P = 0.006). Survey results demonstrated that 16.1% of post-infectious bowel disorder cases and 7.5% of overall IBS cases in a general medical population developed chronic disease within six months of an international trip. Symptoms of established functional bowel disorder in each clinical category were shown to worsen after travel-related acute diarrhea.

Stress-related modulation of inflammation in experimental models of bowel disease and post-infectious irritable bowel syndrome: role of corticotropin-releasing factor receptors

The interaction between gut inflammatory processes and stress is gaining increasing recognition. Corticotropin-releasing factor (CRF)-receptor activation in the brain is well established as a key signaling pathway initiating the various components of the stress response including in the viscera. In addition, a local CRF signaling system has been recently established in the gut. This review summarize the present knowledge on mechanisms through which both brain and gut CRF receptors modulate intestinal inflammatory processes and its relevance towards increased inflammatory bowel disease (IBD) activity and post-infectious irritable bowel syndrome (IBS) susceptibility induced by stress.

Microbial community analysis reveals high level phylogenetic alterations in the overall gastrointestinal microbiota of diarrhoea-predominant irritable bowel syndrome sufferers

Background

A growing amount of scientific evidence suggests that microbes are involved in the aetiology of irritable bowel syndrome (IBS), and the gastrointestinal (GI) microbiota of individuals suffering from diarrhoea-predominant IBS (IBS-D) is distinguishable from other IBS-subtypes. In our study, the GI microbiota of IBS-D patients was evaluated and compared with healthy controls (HC) by using a high-resolution sequencing method. The method allowed microbial community analysis on all levels of microbial genomic guanine plus cytosine (G+C) content, including high G+C bacteria.

Methods

The collective faecal microbiota composition of ten IBS-D patients was analysed by examining sequences obtained using percent G+C (%G+C) -based profiling and fractioning combined with 16S rRNA gene clone library sequencing of 3267 clones. The IBS-D library was compared with an analogous healthy-control library of 23 subjects. Real-time PCR analysis was used to identify phylotypes belonging to the class Gammaproteobacteria and the order Coriobacteriales.

Results

Significant differences were found between clone libraries of IBS-D patients and controls. The microbial communities of IBS-D patients were enriched in Proteobacteria and Firmicutes, but reduced in the number of Actinobacteria and Bacteroidetes compared to control. In particular, 16S rDNA sequences belonging to the family Lachnospiraceae within the phylum Firmicutes were in greater abundance in the IBS-D clone library.

Conclusions

In the microbiota of IBS-D sufferers, notable differences were detected among the prominent bacterial phyla (Firmicutes, Actinobacteria, Bacteroidetes, and Proteobacteria) localized within the GI tract.

The role of diet in symptoms of irritable bowel syndrome in adults: a narrative review

This review summarizes what is known about the effect of diet on irritable bowel syndrome (IBS) symptoms emphasizing data from randomized, controlled clinical trials. Studies suggest that IBS symptoms in one quarter of patients may be caused or exacerbated by one or more dietary components. Recent studies indicate that a diet restricted in fermentable, poorly absorbed carbohydrates, including fructose, fructans (present in wheat and onions), sorbitol, and other sugar alcohols is beneficial, but confirmatory studies are needed. Despite a long history of enthusiastic use, fiber is marginally beneficial. Insoluble fiber may worsen symptoms. Some patients with IBS, especially those with constipation, will improve with increased intake of soluble fiber. Prebiotic fibers have not been adequately tested. Daily use of peppermint oil is effective in relieving IBS symptoms. The usefulness of probiotics in the form of foods such as live-culture yogurt and buttermilk for IBS symptoms is not established. In clinical practice, it is very difficult to establish that a patient's symptoms result from an adverse reaction to food. A double blind placebo-controlled food challenge is the most reliable method, but it is not suitable for routine clinical use. A modified exclusion diet and stepwise reintroduction of foods or trials of eliminating classes of food may be useful.

Dextran sulfate sodium-induced low grade mucosal inflammation activates visceral hypersensitivity in rats

AIM: To investigate the role of low grade mucosal inflammation (LGMI) induced by dextran sulfate sodium (DSS) in visceral sensitivity of the rats.

METHODS: Forty healthy male Sprague-Dawley (SD) rats were randomly divided into LGMI group and control group (n = 20). LGMI was induced by addition of 15 g/L DSS to drinking water for 7 d, and then distilled water for another 7 d. The control group rats were given distilled water alone. At the 14th day, abdominal withdrawal reflex (AWR) and myoelectric amplitude (MA) of the oblique externus abdominis muscle were recorded respectively after colonic distention by balloon with ascending internal pressure from 20 mmHg to 80 mmHg. The colonic tissue samples were taken for histopathologic examinations (HE staining), and the expressions of c-fos, substance P (SP) and calcitonin gene-related peptide (CGRP) in the intumescentia lumbalis were detected using immunohistochemistry.

RESULTS: The colonic mucosal inflammation score in LGMI rats was 1.56 ± 0.78, significantly higher than that in control rats (0.46 ± 0.54, P = 0.003). Neither the AWR score nor the MA had significant difference between the two groups when the internal balloon pressure was 20 mmHg. When the pressure was up to 40, 60, 80 mmHg, the AWR score and the MA in LGMI rats were significantly higher than those in the control group (all P < 0.05). The expression of c-fos, SP and CGRP in LGMI were respectively higher than those in controls (165.26 ± 10.12 vs 126.52 ± 11.48, 134.28 ± 10.62 vs 120.82 ± 8.92, 157.66 ± 6.25 vs 118.67 ± 5.68, all P < 0.01).

CONCLUSION: Low grade inflammation of colonic mucous induced by DSS in rats may promote expression of the c-Fos, SP, and CGRP in the intumescentia lumbalis, and activate the visceral hypersensitivity, which underlies IBS.

Irritable bowel syndrome and inflammatory bowel disease: infectious gastroenteritis-related disorders?

Infectious gastroenteritis may be one of the important factors in the development of irritable bowel syndrome (IBS), with affected individuals often categorized as having post-infectious IBS (PI-IBS), and is linked to the onset of symptoms in approximately 10-20% of patients diagnosed with IBS. Intestinal mucosal infiltration of T cells and mast cells, and enterochromaffin cell hyperplasia are significant immunological and pathological findings that reveal the pathogenesis of PI-IBS, and results of laboratory studies using animal models of PI-IBS clearly support clinical evidence. Recently, infectious gastroenteritis has also been suggested to be associated with the development of inflammatory bowel disease (IBD), and various studies have suggested that individuals with IBS or IBS-like symptoms may be susceptible to initiation of IBD. However, it is still unclear whether infectious gastroenteritis is directly or indirectly (through PI-IBS) linked to the initiation of IBD. Additional studies are necessary to understand the clinical overlap among infectious gastroenteritis, IBS, and IBD.

Clinical trial: a multistrain probiotic preparation significantly reduces symptoms of irritable bowel syndrome in a double-blind placebo-controlled study

BACKGROUND

The efficacy of probiotics in alleviating the symptoms of irritable bowel syndrome (IBS) appears to be both strain- and dose-related.

AIM

To investigate the effect of LAB4, a multistrain probiotic preparation on symptoms of IBS. This probiotic preparation has not previously been assessed in IBS.

METHODS

Fifty-two participants with IBS, as defined by the Rome II criteria, participated in this double blind, randomized, placebo-controlled study. Participants were randomized to receive either a probiotic preparation comprising two strains of Lactobacillus acidophilus CUL60 (NCIMB 30157) and CUL21 (NCIMB 30156), Bifidobacterium lactis CUL34 (NCIMB 30172) and Bifidobacterium bifidum CUL20 (NCIMB 30153) at a total of 2.5 × 10(10) cfu/capsule or a placebo for 8 weeks. Participants reported their IBS symptoms using a questionnaire fortnightly during the intervention and at 2 weeks post-intervention.

RESULTS

A significantly greater improvement in the Symptom Severity Score of IBS and in scores for quality of life, days with pain and satisfaction with bowel habit was observed over the 8-week intervention period in the volunteers receiving the probiotic preparation than in the placebo group.

CONCLUSION

LAB4 multistrain probiotic supplement may benefit subjects with IBS.