Kevan Jacobson

Experimental colitis alters myenteric nerve function at inflamed and noninflamed sites in the rat

BACKGROUND & AIMS Studies in inflammatory bowel disease have shown extensive structural abnormalities in the enteric nervous system of inflamed and noninflamed gut; however, functional correlates are lacking. The aim of this study was to determine the effect of colitis on myenteric nerve function at inflamed and noninflamed sites in rat intestine. METHODS Tritiated noradrenaline release was measured from longitudinal muscle myenteric plexus preparations from the distal and transverse colon and terminal ileum of rats with colitis induced by trinitrobenzene sulfonic acid or Trichinella spiralis larvae. RESULTS As characterized by myeloperoxidase activity and histology, both models induced inflammation restricted to the distal colon. In distal colon in trinitrobenzene sulfonic acid colitis, KCl- or electrical field stimulation-evoked 3H release was suppressed by 56% and 60%, respectively; in T. spiralis-infected rats, the KCl-evoked release was suppressed by 58%. 3H release was also suppressed by similar magnitudes in noninflamed transverse colon and terminal ileum of each model. CONCLUSIONS Experimental distal colitis alters myenteric nerve function in inflamed distal colon and noninflamed gut regions. These changes are independent of the manner in which colitis is induced and provide a basis for the extensive disruption of physiological function observed in inflammatory bowel disease.

Previous inflammation alters the response of the rat colon to stress

BACKGROUND & AIMS Patients with inflammatory bowel disease have symptoms of irritable bowel syndrome (IBS) with a higher than expected prevalence. Stress is an important factor in the pathogenesis of IBS. Thus, previous inflammation may predispose to IBS by rendering the bowel more susceptible to the impact of stress. The aim of this study was to examine the effect of previous colitis on stress-induced responses in rats. METHODS Acute colitis was induced in rats by intrarectal administration of trinitrobenzene sulfonic acid (TNBS), and the rats were allowed to recover for 6 weeks before application of mild restraint stress for 3 consecutive days. In vitro measurements included myeloperoxidase activity, plasma corticosterone levels, interleukin 1 beta messenger RNA expression, and [3H]noradrenaline release from the myenteric plexus. RESULTS Six weeks after administration of TNBS, stress caused a significant increase in myeloperoxidase activity in TNBS-treated rats but not in stressed controls; plasma corticosterone responses were similar. Stress also caused an exaggerated and significant suppression of [3H]noradrenaline release in TNBS-treated stressed rats compared with stressed controls. This was accompanied by a significant decrease in interleukin 1 beta messenger RNA expression in the colon. CONCLUSIONS Previous colitis rendered the colon more susceptible to effects of stress on enteric nerve function and also increased some parameters of inflammation in response to stress.

A randomized trial of yoga for adolescents with irritable bowel syndrome

BACKGROUND Adolescents with irritable bowel syndrome (IBS) frequently experience interference with everyday activities. Mind-body approaches such as yoga have been recommended as interventions for patients with IBS. Despite promising results among adult samples, there have been limited studies exploring the efficacy of yoga with pediatric patients. OBJECTIVE To conduct a preliminary randomized study of yoga as treatment for adolescents with IBS. METHODS Twenty-five adolescents aged 11 to 18 years with IBS were randomly assigned to either a yoga or wait list control group. Before the intervention, both groups completed questionnaires assessing gastrointestinal symptoms, pain, functional disability, coping, anxiety and depression. The yoga intervention consisted of a 1 h instructional session, demonstration and practice, followed by four weeks of daily home practice guided by a video. After four weeks, adolescents repeated the baseline questionnaires. The wait list control group then received the yoga intervention and four weeks later completed an additional set of questionnaires. RESULTS Adolescents in the yoga group reported lower levels of functional disability, less use of emotion-focused avoidance and lower anxiety following the intervention than adolescents in the control group. When the pre- and postintervention data for the two groups were combined, adolescents had significantly lower scores for gastrointestinal symptoms and emotion-focused avoidance following the yoga intervention. Adolescents found the yoga to be helpful and indicated they would continue to use it to manage their IBS. CONCLUSIONS Yoga holds promise as an intervention for adolescents with IBS.

Inflammatory Bowel Disease in the South Asian Pediatric Population of British Columbia

BACKGROUND:Geographical differences, population migration, and changing demographics suggest an environmental role in prevalence, modulation, and phenotypic expression of inflammatory bowel disease (IBD).AIM:To determine the incidence of IBD and disease subtype in the pediatric South Asian population in British Columbia (BC) compared with non-South Asian IBD patients in the same geographic area.METHODS:Chart review with data collected for all patients ≤16 yr of age diagnosed with IBD at B.C. Childrens hospital, January 1985 to June 2005. Age, gender, family history, duration of symptoms, type, and extent of disease were extracted. Identified South Asian subjects were prospectively interviewed.RESULTS:Seventy-five South Asian patients were diagnosed with IBD, 48% Crohns disease (CD), 33.3% ulcerative colitis (UC), and 18.7% with indeterminate colitis (IC), in contrast to 71%, 18.8%, and 10.2%, respectively, in the non-South Asian population. The incidence rate for South Asian IBD patients, for the period 1996–2001 was 15.19/105 (6.41/105 for CD, 6.70/105 for UC, and 2.08/105 for IC) compared with 5.19/105 for the non-South Asian IBD group (3.69/105, 0.96/105, and 0.54/105, respectively). The South Asian male/female ratio was significantly different from that observed for the rest of the population.CONCLUSION:These data suggest a significantly higher incidence of IBD in the South Asian pediatric population compared with the rest of the BC pediatric population, with a different pattern of phenotypic expression, a male predominance, and more extensive colonic disease. These data suggest a potential effect of migration, and environmental and lifestyle change on the incidence of IBD and disease subtype.

Positron emission tomography in the investigation of pediatric inflammatory bowel disease

Background: Endoscopic and radiologic studies are frequently required in inflammatory bowel disease (IBD) to determine disease activity, extent of disease, and delineating disease type. Positron emission tomography (PET) using fluorine‐18‐fluoro‐deoxyglucose to identify metabolically active tissues may offer a simple noninvasive alternative to conventional studies in identification and localization of active intestinal inflammation in children with IBD. The aim of this study was to assess the value of PET in identifying active intestinal inflammation compared with conventional endoscopic and radiologic studies, including small bowel follow‐through and colonoscopy. Methods: Sixty‐five children were enrolled in the study. This included 55 children (mean age, 13.3 yr; range, 7‐18 yr; 20 girls) with newly diagnosed IBD (37) or symptoms suggestive of recurrent disease (18) and 10 children with recurrent abdominal pain (mean age, 12.7 yr; range, 8‐15 yr; 7 girls) who were studied with PET, and the results were compared with small bowel follow‐through with pneumocolon and/or colonoscopy. Thirty‐eight patients had Crohns disease (17 ileal, 12 ileocolic, 5 pancolonic, 3 left‐sided disease, 1 right‐sided disease), and 17 had ulcerative colitis (15 pan‐colitis, 2 left‐sided colitis). Mean time interval between PET and other studies was 30 ± 17.6 days. Results: PET correctly identified active inflammatory disease in 80% of children with IBD (81.5% with Crohns disease; 76.4% with ulcerative colitis) and correctly showed no evidence of inflammation in children with recurrent abdominal pain. Gluorine‐18‐fluoro‐deoxyglucose accumulated at sites that corresponded with active disease at colonoscopy in 83.8% of patients and with small bowel follow‐through with pneumocolon 75.0% of the time. Conclusion: This study suggests that PET offers a noninvasive tool for identifying and localizing active intestinal inflammation in children with IBD. PET may not be able to replace conventional studies; however, it may be useful when conventional studies cannot be performed or fail to be completed.

The mechanism of altered neural function in a rat model of acute colitis

BACKGROUND & AIMS Distal colitis induced in rats by trinitrobenzene sulfonic acid (TNBS) causes a suppression of [3H]noradrenaline release from the myenteric plexus, of inflamed distal colon, as well as in noninflamed regions of colon and ileum. The aim of this study was to explore the mechanisms underlying these neural changes in TNBS colitis. METHODS Colitis was induced by intrarectal administration of TNBS, and the animals were killed on day 5. Inflammation was assessed by measuring myeloperoxidase (MPO) activity, and noradrenaline release was measured as 3H release from rats myenteric plexus preparations preloaded with [3H]noradrenaline. These end points were examined: (1) after administration of the locally active steroid budesonide; (2) in congenitally athymic rats; and (3) in rats treated with the interleukin 1 receptor antagonist (IL-1ra) to interleukin 1 beta. RESULTS In colitis, both topical budesonide and systemic IL-1ra treatments attenuated the suppression of KCl-evoked 3H release from longitudinal muscle myenteric plexus in both inflamed and noninflamed segments. However, neither of these treatments altered MPO activity. A similar suppression of [3H]noradrenaline release was observed in athymic rats after TNBS, although there was a substantially greater increase in MPO activity compared with euthymic rats with colitis. CONCLUSIONS TNBS-induced colitis alters myenteric nerve function at inflamed and noninflamed sites via a steroid-sensitive and interleukin 1-mediated process that does not require T lymphocytes.

Citrobacter rodentium infection causes both mitochondrial dysfunction and intestinal epithelial barrier disruption in vivo: role of mitochondrial associated protein (Map).

Enteropathogenic Escherichia coli (EPEC) and enterohaemorrhagic E. coli are non‐invasive attaching/effacing (A/E) bacterial pathogens that infect their host’s intestinal epithelium, causing severe diarrhoeal disease. These bacteria utilize a type III secretion apparatus to deliver effector molecules into host cells, subverting cellular function. Mitochondrial associated protein (Map) is a multifunctional effector protein that targets host cell mitochondria and contributes to infection‐induced epithelial barrier dysfunction in vitro. Unfortunately, the relevance of these actions to the pathogenesis of EPEC‐induced disease is uncertain. Using Citrobacter rodentium, a mouse‐adapted A/E bacterium, we found that Map colocalized with host cell mitochondria, and that in vivo infection led to a disruption of mitochondrial morphology in infected colonocytes as assessed by electron microscopy. Histochemical staining for the mitochondrial enzyme succinate dehydrogenase also revealed a significant loss of mitochondrial respiratory function in the infected intestinal epithelium; however, both pathologies were attenuated in mice infected with a Δmap strain. C. rodentium Map was also implicated in the disruption of epithelial barrier function both in vitro and in vivo. These studies thus advance our understanding of how A/E pathogens subvert host cell functions and cause disease, demonstrating that Map contributes to the functional disruption of the intestinal epithelium during enteric infection by C. rodentium.

Modulation of Inducible Nitric Oxide Synthase Expression by the Attaching and Effacing Bacterial Pathogen Citrobacter rodentium in Infected Mice

ABSTRACT Citrobacter rodentium belongs to the attaching and effacing family of enteric bacterial pathogens that includes both enteropathogenic and enterohemorrhagic Escherichia coli. These bacteria infect their hosts by colonizing the intestinal mucosal surface and intimately attaching to underlying epithelial cells. The abilities of these pathogens to exploit the cytoskeleton and signaling pathways of host cells are well documented, but their interactions with the hosts antimicrobial defenses, such as inducible nitric oxide synthase (iNOS), are poorly understood. To address this issue, we infected mice with C. rodentium and found that iNOS mRNA expression in the colon significantly increased during infection. Immunostaining identified epithelial cells as the major source for immunoreactive iNOS. Finding that nitric oxide (NO) donors were bacteriostatic for C. rodentium in vitro, we examined whether iNOS expression contributed to host defense by infecting iNOS-deficient mice. Loss of iNOS expression caused a small but significant delay in bacterial clearance without affecting tissue pathology. Finally, immunofluorescence staining was used to determine if iNOS expression was localized to infected cells by staining for the C. rodentium virulence factor, translocated intimin receptor (Tir), as well as iNOS. Interestingly, while more than 85% of uninfected epithelial cells expressed iNOS, fewer than 15% of infected (Tir-positive) cells expressed detectable iNOS. These results demonstrate that both iNOS and intestinal epithelial cells play an active role in host defense during C. rodentium infection. However, the selective expression of iNOS by uninfected but not infected cells suggests that this pathogen has developed mechanisms to locally limit its exposure to host-derived NO.

Myenteric plexus injury and apoptosis in experimental colitis

Intestinal inflammatory conditions are associated with structural and functional alterations of the enteric nervous system (ENS). While injury to the enteric nervous system is well described, the mechanisms of neuronal injury and neuronal cell loss remain unclear. The aim of the present study was to examine the neural consequences of distal colitis and to assess the role of neutrophil granulocytes in mediating these changes. Colitis was induced in C3H/HEN female mice with dinitrobenzene sulfonic acid. The mice were then sacrificed at 0.5, 1, 1.5, 2, 3, 4, 6, 12, 24, 120 h post instillation of dinitrobenzene sulfonic acid. The inflammatory response was assessed by macroscopic damage score, myeloperoxidase activity and histology. HuC/D and PGP 9.5 immunostaining was used to examine myenteric plexus density and structure, neural cell body numbers and distribution in cross-section and whole mount preparations. Apoptosis was investigated in whole mount preparations double stained with HuC/D and activated caspase-3 or cleaved poly (ADP-ribose) polymerase (PARP). Dinitrobenzene sulfonic acid-induced colitis was associated with a rapid and significant loss of HuC/D immunoreactive myenteric plexus neuronal cell bodies (42% decrease relative to control) that remained unchanged between 6 and 120 h. No change in myenteric plexus density was observed with PGP 9.5 immunostaining. Neuronal apoptosis was evident between 0.5 and 3 h. PARP immunoreactive neurons ranged between 1% and 2.5%. Colitis was associated with significant impairment in colonic propulsive function. Pre-treatment of mice with anti-neutrophil serum attenuated the inflammatory response and partially reduced the extent of myenteric plexus neuronal cell loss. Taken together, these data suggest that acute colitis is associated with loss of myenteric plexus neurons that is partly mediated by neutrophil granulocyte infiltration and is accompanied by impairment of colonic motility.

18F-fluorodeoxyglucose positron tomography in diagnosis of paediatric inflammatory bowel disease

Existing techniques for the diagnosis of inflammatory bowel disease in children are generally less than ideal. Positron tomography with fluorine-18-labelled fluorodeoxyglucose provides adequate information in patients with suspected inflammatory bowel disease.