Escherichia coli Nissle 1917 restores epithelial permeability alterations induced by irritable bowel syndrome mediators.

BACKGROUND: Intestinal permeability is altered in a subgroup of irritable bowel syndrome (IBS) patients and may contribute to symptom development. The aim of this study was to evaluate the in vitro effect of the probiotic Escherichia coli Nissle 1917 (EcN) on Caco-2 permeability alterations induced by mediators released by IBS mucosal biopsies compared to asymptomatic controls (AC). METHODS: Caco-2 cells were used as an in vitro model of intestinal permeability. Seven AC and 28 well-phenotyped IBS (9 IBS-D, 8 IBS-C, and 11 IBS-M) patients were enrolled. Mucosal mediators spontaneously released (SUP) by IBS and AC biopsies were collected. Two concentrations of EcN (108 and 106 ) were applied to Caco-2 with or without SUP or SLIGRL (a protease-activated receptor-2 activating peptide), tumor necrosis factor-α, and interferon-γ. Paracellular permeability was assessed by evaluating the flow of sulfonic-acid conjugated to fluorescein through Caco-2 monolayer. KEY RESULTS: EcN 108 significantly reinforced Caco-2 monolayer compared to cells incubated with medium alone. IBS SUP induced a significant increase in paracellular permeability compared to AC SUP, independently of IBS bowel habit. EcN 108 induced a significant recovery of permeability rate compared to IBS SUP. Permeability increase induced by IBS SUP significantly correlated with severity and frequency of abdominal pain and abdominal distension. The co-incubation of EcN and IBS SUP abolished the above significant correlations. CONCLUSIONS AND INFERENCES: EcN reinforces the integrity of Caco-2 monolayer and reverts the increase of permeability induced by mediators released by IBS biopsies. Future studies should investigate EcN therapeutic potentials in IBS.

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

BACKGROUND & AIMS: Increases in mucosal immune cells have frequently been observed in irritable bowel syndrome (IBS) patients. However, this finding is not completely consistent between studies, possibly due to a combination of methodological variability, population differences and small sample sizes. We performed a meta-analysis of case-control studies that compared immune cell counts in colonic biopsies of IBS patients and controls. METHODS: PubMed and Embase were searched in February 2017. Results were pooled using standardized mean difference (SMD) and were considered significant when zero was not within the 95% confidence interval (CI). Heterogeneity was assessed based on I2 statistics where I2  ≤ 50% and I2  > 50% indicated fixed and random effect models, respectively. KEY RESULTS: Twenty-two studies on 706 IBS patients and 401 controls were included. Mast cells were increased in the rectosigmoid (SMD: 0.38 [95% CI: 0.06-0.71]; P = .02) and descending colon (SMD: 1.69 [95% CI: 0.65-2.73]; P = .001) of IBS patients. Increased mast cells were observed in both constipation (IBS-C) and diarrhea predominant IBS (IBS-D). CD3+ T cells were increased in the rectosigmoid (SMD: 0.53 [95% CI: 0.21-0.85]; P = .001) and the descending colon of the IBS patients (SMD: 0.79, 95% CI [0.28-1.30]; P = .002). This was possibly in relation to higher CD4+ T cells in IBS (SMD: 0.33 [95% CI: 0.01-0.65]; P = .04) as there were no differences in CD8+ T cells. CONCLUSIONS & INFERENCES: Mast cells and CD3+ T cells are increased in colonic biopsies of patients with IBS vs non-inflamed controls. These changes are segmental and sometimes IBS-subtype dependent. The diagnostic value of the quantification of colonic mucosal cells in IBS requires further investigation.

Randomised clinical trial: the analgesic properties of dietary supplementation with palmitoylethanolamide and polydatin in irritable bowel syndrome.

BACKGROUND: Intestinal immune activation is involved in irritable bowel syndrome (IBS) pathophysiology. While most dietary approaches in IBS involve food avoidance, there are fewer indications on food supplementation. Palmithoylethanolamide, structurally related to the endocannabinoid anandamide, and polydatin are dietary compounds which act synergistically to reduce mast cell activation. AIM: To assess the effect on mast cell count and the efficacy of palmithoylethanolamide/polydatin in patients with IBS. METHODS: We conducted a pilot, 12-week, randomised, double-blind, placebo-controlled, multicentre study assessing the effect of palmithoylethanolamide/polydatin 200 mg/20 mg or placebo b.d. on low-grade immune activation, endocannabinoid system and symptoms in IBS patients. Biopsy samples, obtained at screening visit and at the end of the study, were analysed by immunohistochemistry, enzyme-linked immunoassay, liquid chromatography and Western blot. RESULTS: A total of 54 patients with IBS and 12 healthy controls were enrolled from five European centres. Compared with controls, IBS patients showed higher mucosal mast cell counts (3.2 ± 1.3 vs. 5.3 ± 2.7%, P = 0.013), reduced fatty acid amide oleoylethanolamide (12.7 ± 9.8 vs. 45.8 ± 55.6 pmol/mg, P = 0.002) and increased expression of cannabinoid receptor 2 (0.7 ± 0.1 vs. 1.0 ± 0.8, P = 0.012). The treatment did not significantly modify IBS biological profile, including mast cell count. Compared with placebo, palmithoylethanolamide/polydatin markedly improved abdominal pain severity (P < 0.05). CONCLUSIONS: The marked effect of the dietary supplement palmithoylethanolamide/polydatin on abdominal pain in patients with IBS suggests that this is a promising natural approach for pain management in this condition. Further studies are now required to elucidate the mechanism of action of palmithoylethanolamide/polydatin in IBS. ClinicalTrials.gov number, NCT01370720.

Supernatants of irritable bowel syndrome mucosal biopsies impair human colonic smooth muscle contractility.

BACKGROUND: Changes in intestinal motility are likely to contribute to irritable bowel syndrome (IBS) pathophysiology. The aim of the study was to investigate the effects of IBS mucosal supernatants on human colonic muscle contractility. METHODS: Supernatants were obtained from biopsies of 18 IBS patients-nine with constipation (IBS-C) and nine with diarrhea-predominant IBS (IBS-D)-and nine asymptomatic subjects, used as controls. Colonic circular smooth muscle strips or isolated cells (SMC) were exposed to control or IBS supernatants. Spontaneous phasic contractions on strips and morphofunctional parameters on cells were evaluated in basal conditions and in response to acetylcholine (Ach). Incubation with IBS supernatants was also conducted in the presence of antagonists and inhibitors (namely histamine, protease and prostaglandin antagonists, nuclear factor-kappa B inhibitor, catalase, NADPH oxidase inhibitor, and the cAMP- and/or cGMP-cyclase inhibitors). KEY RESULTS: Exposure to IBS-C and IBS-D supernatants induced a significant reduction in basal tone and Ach-elicited contraction of muscle strips and a significant shortening and impairment of Ach contraction of SMCs. The NADPH oxidase inhibitor prevented the effect of supernatants, while the protease antagonist only IBS-C effect. No effect was observed with the other antagonists and inhibitors. Dilution of IBS-D supernatants partially restored the effects only on SMCs, whereas dilution of IBS-C supernatants significantly reverted the effects on muscle strips and Ach-elicited response on SMC. CONCLUSIONS & INFERENCES: Supernatants from mucosal biopsies of IBS patients reduce colonic contractility. The observed impairment was concentration dependent, likely occurring through intracellular oxidative stress damage, involving different neuromotor mechanisms depending on the IBS subtype.

[Some practical questions on chronic stipsis treatment with prucalopride]. / Alcune domande pratiche sulla terapia della stipsi cronica con prucalopride.

Chronic constipation is a frequent pathological condition bearing relevant socioeconomic burdens, mainly due to uncertain management and unsatisfactory response to traditional laxatives. Prucalopride is a novel enterokinetic drug, that has been demonstrated to improve bowel functions and relieve a broad spectrum of digestive symptoms in patients with severe chronic constipation who had failed to respond to various traditional laxatives. In this paper we discussed the practical aspects of chronic constipation treatment, in particular focusing on some questions about the practical use of prucalopride. Prucalopride is a potent, selective, high-affinity agonist of the 5-HT4 receptors widely expressed in the gastrointestinal tract. Unlike other 5-HT4 agonists, such as cisapride and tegaserod, it is devoid of adverse cardiovascular effects. Furthermore, it is characterized by a low potential for interactions with other drugs, due to its pharmacokinetic characteristics. Prucalopride was approved, in 2009, by the European Medicines Agency for the symptomatic treatment of chronic constipation in women in whom laxatives fail to provide adequate relief, however, there are ongoing studies to extend the use of the drug even to males.

Neuroimmune interactions at different intestinal sites are related to abdominal pain symptoms in children with IBS.

BACKGROUND: Neuroimmune interactions and inflammation have been proposed as factors involved in sensory-motor dysfunction and symptom generation in adult irritable bowel syndrome (IBS) patients. In children with IBS and healthy controls, we measured ileocolonic mast cell infiltration and fecal calprotectin and evaluated the relationships between these parameters and abdominal pain symptoms and stooling pattern. METHODS: Irritable bowel syndrome patients diagnosed according to Pediatric Rome III criteria and healthy controls kept a 2-week pain/stooling diary. Ileocolonic mucosal mast cells (MC) and MC in close proximity to nerve fibers (MC-NF) were identified immunohistochemically and quantified. Fecal calprotectin concentration was measured. KEY RESULTS: 21 IBS patients and 10 controls were enrolled. The MC-NF count was significantly higher in the ileum (p = 0.01), right colon (p = 0.04), and left colon (p < 0.001) of IBS patients compared with controls. No differences in fecal calprotectin concentration were noted. Abdominal pain intensity score correlated with ileal MC count (r(s) = 0.47, p = 0.030) and right colon MC-NF count (r(s) = 0.52, p = 0.015). In addition, children with IBS with >3 abdominal pain episodes/week had greater ileal (p = 0.002) and right colonic (p = 0.01) MC counts and greater ileal (p = 0.05) and right colonic (p = 0.016) MC-NF counts than children with less frequent pain. No relationship was found between MC and MC-NF and fecal calprotectin or stooling pattern. CONCLUSIONS & INFERENCES: Mast cells-nerve fibers counts are increased in the ileocolonic mucosa of children with IBS. Mast cells and MC-NF counts are related to the intensity and frequency of abdominal pain.

Colonic mucosal mediators from patients with irritable bowel syndrome excite enteric cholinergic motor neurons.

BACKGROUND: Mediators released in the mucosal milieu have been suggested to be involved in visceral hypersensitivity and abdominal pain in patients with irritable bowel syndrome (IBS). However, their impact on myenteric neurons remains unsettled. METHODS: Mucosal biopsies were obtained from the descending colon of patients with IBS and controls. Mucosal mast cells were identified immunohistochemically. The impact of spontaneously released mucosal mediators on guinea pig electrically stimulated longitudinal muscle myenteric plexus (LMMP) preparations was assessed in vitro by means of selective receptor antagonists and inhibitors. KEY RESULTS: Patients with IBS showed an increased mast cell count compared with controls. Application of mucosal mediators of IBS to LMMPs potentiated cholinergic twitch contractions, an effect directly correlated with mast cell counts. Enhanced contractions were inhibited by 50.3% with the prostaglandin D2 antagonist BW A868C, by 31.3% and 39% with the TRPV1 antagonists capsazepine and HC-030031, respectively, and by 60.5% with purinergic P2X antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid. Conversely, the serotonin1-4, histamine1-3, tachykinin1-3 receptor blockade, and serine protease inhibition had no significant effect. CONCLUSIONS & INFERENCES: Colonic mucosal mediators from patients with IBS excite myenteric cholinergic motor neurons. These effects were correlated with mast cell counts and mediated by activation of prostanoid receptors, TRPV1, and P2X receptors. These results support the role of mucosal inflammatory mediators and mast cell activation in altered motor function of IBS.

Patient-reported outcomes and gut dysmotility in functional gastrointestinal disorders.

BACKGROUND: Unlike chronic idiopathic intestinal pseudo-obstruction (CIIP), severe digestive syndromes that are not characterized by episodes resembling mechanical obstruction remain poorly characterized. The present study compared clinical features, small bowel motility, and quality of life (QoL) in patients with CIIP or severe functional gastrointestinal disorders (SFGID), compared to irritable bowel syndrome (IBS). METHODS: We enrolled 215 consecutive patients: 70 CIIP, 110 malnourished SFGID [body mass index (BMI) 17.8±1.8kg m(-2) ] and 35 non-malnourished SFGID (BMI 22.8±3.6kgm(-2) ). KEY RESULTS: Abnormal motor patterns that fulfilled diagnostic criteria for small bowel dysmotility were virtually absent in IBS patients, but were recorded in69 CIIP patients (98.6%), 82 malnourished SFGID patients (74.5%;), and 23 SFGID patients without malnutrition (65.7%) (P<0.0001). CIIP patients presented more frequently abnormal activity fronts, lack of response to feeding, and hypomotility than malnourished and non-malnourished SFGID patients (61.4%vs 42.7% and 31.4%, P<0.05 only vs non-malnourished SFGID; 8.6%vs 0.9% and 2.9%; 21.4%vs 0.9% and 0%, P<0.05). Quality of life mean scores were all significantly lower in CIIP patients and malnourished SFGID patients than in IBS. Bodily pain, general health, and vitality scores were lower in CIIP also compared to non-malnourished SFGID. CONCLUSIONS & INFERENCES: Chronic idiopathic intestinal pseudo-obstruction and SFGIDs are frequently associated with small bowel dysmotility and marked derangements of QoL which are significantly more severe than in IBS and result particularly in being severe in patients with recurrent sub occlusive episodes or inability to maintain a normal body weight.

[Post-infectious irritable bowel syndrome]. / Sindrome dell'Intestino Irritabile Post-infettivo.

Acute infectious gastroenteritis is the strongest known risk factor for the development of irritable bowel syndrome (IBS), one of the most common functional gastrointestinal disorders. The knowledge about the incidence and prevalence of post-infectious IBS (PI-IBS) in the general population is still limited. Risk factors have been identified in the development of PI-IBS. These include the virulence of the pathogen, younger age, female sex, the long duration of the initial illness and the presence of psychological disturbances. Histopathologic data demonstrate a low-grade mucosal inflammation in a subset of patients with IBS. Furthermore, a change in intestinal microflora could also be involved although confirmatory studies are required. The use of probiotics or non absorbable antibiotics during the acute infective episode could play a preventive role. Nonetheless, the discovery that an infective episode may trigger the development of IBS has not substantially changed the clinical management of this subset of patients compared to the classical (non infective) form of IBS. Future studies aimed at identifying specific therapies are waited.

Natural history of intestinal failure induced by chronic idiopathic intestinal pseudo-obstruction.

Chronic intestinal pseudo-obstruction is a severe, often unrecognized disease characterized by disabling and potentially life-threatening complications over time. The diagnosis is based on the evidence of typical clinical manifestations, radiological evidence of distended bowel loops with air-fluid levels, and the exclusion of any organic obstruction of the gut lumen. The radiological sign of intestinal occlusion allows the distinction from enteric dysmotility, which is characterized by better outcomes. Manometry can play a supportive role in defining the diagnosis, and differences in the manometric pattern of chronic intestinal pseudo-obstruction and enteric dysmotility have been shown. The disease is often unrecognized, and the diagnosis, therefore, delayed by several years. Thus, the majority of patients undergo useless and potentially dangerous surgeries. Long-term outcomes are generally poor despite surgical and medical therapies characterized by disabling and potentially life-threatening complications over time. A substantial percentage of patients requires parenteral nutrition. Failure of this nutritional support represents an indication for small bowel transplantation.

Effect of mesalazine on mucosal immune biomarkers in irritable bowel syndrome: a randomized controlled proof-of-concept study.

BACKGROUND: Intestinal immune infiltration contributes to symptoms in patients with irritable bowel syndrome (IBS). AIM: To assesses the effect of mesalazine (mesalamine) on mucosal immune cells in patients with IBS, through a pilot study. METHODS: A randomized, double-blind, placebo-controlled trial in 20 patients with IBS in tertiary care setting. Patients were randomized to receive placebo or 800 mg mesalazine three times daily for 8 weeks. The primary endpoint was a significant reduction in total colonic immune cells on biopsies obtained at the end of treatment compared to baseline. Secondary endpoints included effects on subsets of immune cells, inflammatory mediators and symptom severity. Intention-to-treat analysis was performed. RESULTS: Mesalazine markedly reduced immune cells as compared with placebo (P = 0.0082); this effect was ascribed to a marked inhibition of mast cells (P = 0.0014). Mesalazine significantly increased general well-being (P = 0.038), but had no significant effects on abdominal pain (P = 0.084), bloating (P = 0.177) or bowel habits. No serious drug-related adverse events were reported during the study. CONCLUSIONS: Mesalazine is an effective and safe approach to reduce mast cell infiltration and may improve general well-being in patients with IBS. These results support the hypothesis that immune mechanisms represent potential therapeutic targets in IBS.

Impaired intestinal barrier integrity in the colon of patients with irritable bowel syndrome: involvement of soluble mediators.

BACKGROUND: Growing evidence suggests that patients with irritable bowel syndrome (IBS) have increased intestinal permeability. In addition, mucosal soluble mediators are involved in the pathophysiology of pain in IBS. We aimed to investigate (1) paracellular permeability in colonic biopsies of patients with IBS; and (2) the ability of soluble factors from colonic biopsies to reproduce these alterations in vitro. METHODS: Paracellular permeability in colonic biopsies of healthy subjects and patients with IBS was measured by mounting the biopsies in Ussing chambers. Cleared supernatant (SUP) of the culture from colonic biopsies was collected and applied to Caco-2 cells for 48 h. Paracellular permeability and transepithelial resistance (TER) were evaluated. mRNA expression of the tight junction proteins, zonula occludens (ZO)-1 and occludin, was assessed in colonic biopsies. Abdominal pain was assessed using a validated questionnaire. RESULTS: Permeability of colonic biopsies was significantly higher in patients with IBS compared to healthy subjects. These changes were associated with significantly lower expression of ZO-1 mRNA in biopsies of IBS as compared to healthy subjects. Compared to healthy subjects, SUP of IBS markedly reduced TER and significantly increased permeability in Caco-2 cells. SUP of IBS patients induced a significant decrease of ZO-1 mRNA in Caco-2 as compared to healthy subjects. SUP-induced increased paracellular permeability correlated with the severity of abdominal pain. CONCLUSIONS: Our study shows that colonic soluble mediators are able to reproduce functional (permeability) and molecular (ZO-1 mRNA expression) alterations observed in IBS patients. These findings might pave the way both to identify novel biomarkers as well as new therapeutic targets in IBS.

[Gastroesophageal reflux disease: therapeutic features (Part II)]. / La malattia da reflusso gastro-esofageo: aspetti terapeutici (Parte II).

Gastroesophageal reflux disease (GERD) can be defined as a condition resulting from the reflux of stomach contents into the esophagus. Its pharmacological treatment is aimed at symptom relief, healing of erosions and ulcerations and prevention of relapses. Based on the pathophysiology, the ideal treatment is directed to enhance basal sphincter pressure or decrease the frequency of TLESR, restore esophageal "clearance", accelerate gastric emptying and highten mucosal resistance as well as reduce or inhibit gastric acid secretion. Most of these targets are currently achievable because the availability of different types of drugs, however the "ideal" pharmacologic treatment of GERD does not exist. Current remedies for GERD include life style changes along with a wide array of antisecretory drugs, such as antacids, H2-antagonists and proton pump inhibitors (PPI). Surgery, based on anti-reflux procedures, and endoscopic approaches may have a role in the management of patients with GERD.

[Gastroesophageal reflux disease: clinical and pathophysiological features (part I)]. / La malattia da reflusso gastro-esofageo: aspetti clinici e fisio- patologici (Parte I).

Gastroesophageal reflux disease (GERD) can be described as a clinical picture resulting from the reflux of stomach contents into the esophagus. The actual prevalence of GERD remains unestablished, although this disorder is generally common in old patients, male sex and in subsets of patients with pulmonary manifestations such as asthma. From a pathophysiological stand-point, GERD is thought to have a multifactorial etiology which involves genetics, anatomical, functional, environmental, hormonal and pharmacological factors. GERD has different clinical presentations which may be divided in three main classes: typical symptoms (heartburn and regurgitation); atypical or extraesophageal symptoms (angina-like chest pain, asthma, chronic cough and laryngitis); and complications (ulcers, strictures and Barrett's esophagus). In GERD diagnosis a key role is played by: accurate symptom evaluation, response to proton pump inhibitors and, finally, at least one in a life-time endoscopy. Moreover, barium swallow X-ray, 24-h esophageal pH monitoring and gastro-esophageal manometry can be useful to support diagnosis in some unusual cases or in cases partially or unresponsive to standard pharmacologic treatment.

Idiopathic achalasia is not allelic to alacrima achalasia adrenal insufficiency syndrome at the ALADIN locus.

BACKGROUND: Evidence indicates that patients with familial achalasia associated with Allgrove or triple-A syndrome (i.e. alacrima, achalasia and adrenocorticotropin-resistant adrenal insufficiency with neurological impairment) have mutations of the alacrima achalasia adrenal insufficiency syndrome (AAAS) gene. AIM: The present study was aimed at identifying possible AAAS gene mutations in patients with established idiopathic non-familial achalasia. METHODS: Genomic DNA of 41 patients was isolated from peripheral blood cells using standard methods. The 16 exons of the AAAS gene (or ALADIN) were screened for mutations using the denaturing high-performance liquid chromatography method. RESULTS: Four heterozygous nucleotidic variations have been identified in patients with idiopathic achalasia, among which three were exonic conservative polymorphisms [i.e. D138D (GAT-->GAC), L227L (TTG-->CTG) and F285F (TTC-->TTT) in exons 5, 7 and 9, respectively]. The fourth nucleotidic variation was located in intron 13 (IVS14-23delT). All variants have been regarded as polymorphisms resulting in a normal ALADIN protein since they are either conservative or lying outside the consensus splice sites. CONCLUSIONS: Our data do not support a pathogenetic role for common AAAS gene mutations in patients with idiopathic achalasia as seen in Allgrove syndrome. These findings suggest the participation of different mechanisms in the pathogenesis of idiopathic achalasia.

Diagnosis and therapy of irritable bowel syndrome.

Irritable bowel syndrome (IBS) is one of the most common gut functional diseases, affecting 10-20% of people worldwide. Although most patients do not seek medical help, the disease accounts for huge costs for both patients and health-care systems and worsens significantly patients' quality of life. Diagnosis is based on the identification of symptoms according to Manning, Rome I and Rome II criteria and exclusion of alarm indicators. IBS symptoms overlap with those of coeliac disease, lactose intolerance, food allergies and bile salt malabsorption. The treatment of IBS is centred on an excellent doctor-patient relationship along with drugs targeting the predominant symptom, especially during exacerbations. Current pharmacological remedies are unsatisfactory due to the high number of patients complaining of lack of response and/or symptom recurrence. Although useful in some IBS patients, the validity of psychotherapy deserves further investigation. A wide array of potentially useful drugs are currently under consideration in pre-clinical trials. A better understanding of the pathogenetic mechanisms underlying IBS may help to develop more effective drugs for this disease.

New pathophysiological mechanisms in irritable bowel syndrome.

Irritable bowel syndrome (IBS) is a functional, multifactorial disease characterized by abdominal pain and erratic bowel habit. Changes in gastrointestinal motor function, enhanced perception of stimuli arising from the gut wall and psychosocial factors are thought to be major contributors for symptom generation. In recent years, several additional factors have been identified and postulated to interact with these classical mechanisms. Reduced ability to expel intestinal gas with consequent gas trapping and bowel distension may contribute to abdominal discomfort/pain and bloating. Abnormal activation of certain brain regions following painful stimulation of the rectum suggests altered processing of afferent signals. An acute gastrointestinal infection is now a recognized aetiological factor for symptom development in a subset of IBS patients (i.e. post-infectious IBS), who are probably unable to down-regulate the initial inflammatory stimulus efficiently. Furthermore, low-grade inflammatory infiltration and activation of mast cells in proximity to nerves in the colonic mucosa may also participate in the frequency and severity of perceived abdominal pain in post-infectious and non-specific IBS. Initial evidence suggests the existence of changes in gut microflora, serotonin metabolism and a genetic contribution in IBS pathophysiology. These novel mechanisms may aid a better understanding of the complex pathophysiology of IBS and to develop new therapies.

New insights into human enteric neuropathies.

The functioning of enteric neuronal circuitries has been elucidated in the recent past. Evidence is now gathering to explain how dysfunction of the enteric nervous system (ENS) may lead to human gastrointestinal motor disorders. These conditions include achalasia, congenital hypertrophic pyloric stenosis, chronic intestinal pseudo-obstruction, Hirschsprung's disease, chronic idiopathic constipation, and probably irritable bowel syndrome. Degenerative, inflammatory and genetic mechanisms exert a critical role in ENS dysfunction underlying gut dysmotility. The study of the ENS abnormalities in gut dysmotility provides a framework to better understand the mechanisms involved in degeneration and neuronal loss and fosters the development of targeted therapeutic options.

Neutral endopeptidase (EC 3.4.24.11) downregulates the onset of intestinal inflammation in the nematode infected mouse.

BACKGROUND AND AIMS: Substance P (SP) release from sensory nerves induces neurogenic inflammation. Neutral endopeptidase (NEP) degrades SP, thereby limiting its proinflammatory effects. Intestinal inflammation following Trichinella spiralis infection markedly downregulates NEP, resulting in diminished SP degradation, with unknown functional consequences. We hypothesised that diminished expression of NEP would exacerbate T spiralis induced enteritis. METHODS: NEP knockout (NEP-/-) and wild-type (NEP+/+) mice were infected with T spiralis and studied at 6, 12, 24, and 48 hours post infection (PI). Tissue inflammation was quantified by computerised cell counting and myeloperoxidase activity (MPO). The leucocyte adhesion molecule, intercellular adhesion molecule 1 (ICAM-1), and SP were assessed by immunohistochemistry. RESULTS: Before infection, the lack of NEP was not associated with changes in mucosal cellularity or MPO activity. Twelve hours PI, NEP-/- mice showed a 2.5-fold increase in MPO activity at a time when values in NEP+/+ mice were still within normal limits. MPO activity and cellularity peaked at 24 hours PI. This was accompanied by increased staining for both ICAM-1 and SP in NEP-/- mice. Infusion of rhNEP to NEP-/- mice significantly reduced MPO activity 24 hours PI. CONCLUSIONS: These findings demonstrate that NEP downregulates the early onset of nematode intestinal inflammation and that increased bioavailability of SP and overexpression of ICAM-1 in NEP-/- mice likely play a role in the earlier onset of intestinal inflammation.

A role for inflammation in irritable bowel syndrome?

Attention has been directed to the putative role of low grade mucosal inflammation in irritable bowel syndrome (IBS) on the basis of evidence showing that some patients with IBS have an increased number of inflammatory cells in the colonic and ileal mucosa. Previous episodes of infectious enteritis, genetic factors, undiagnosed food allergies, and changes in bacterial microflora may all play a role in promoting and perpetuating this low grade inflammatory process. Human and animal studies support the concept that inflammation may perturb gastrointestinal reflexes and activate the visceral sensory system even when the inflammatory response is minimal and confined to the mucosa. Thus abnormal neuroimmune interactions may contribute to the altered gastrointestinal physiology and hypersensitivity that underlies IBS. A brief review of the human and animal studies that have focused on the putative role of intestinal inflammation and infections in the pathogenesis of IBS is given.