Guidelines on eosinophilic esophagitis: evidence-based statements and recommendations for diagnosis and management in children and adults

INTRODUCTION

Eosinophilic esophagitis (EoE) is one of the most prevalent esophageal diseases and the leading cause of dysphagia and food impaction in children and young adults. This underlines the importance of optimizing diagnosys and treatment of the condition, especially after the increasing amount of knowledge on EoE recently published. Therefore, the UEG, EAACI ESPGHAN, and EUREOS deemed it necessary to update the current guidelines regarding conceptual and epidemiological aspects, diagnosis, and treatment of EoE.

METHODS

General methodology according to the Appraisal of Guidelines for Research and Evaluation (AGREE) II and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system was used in order to comply with current standards of evidence assessment in formulation of recommendations. An extensive literature search was conducted up to August 2015 and periodically updated. The working group consisted of gastroenterologists, allergists, pediatricians, otolaryngologists, pathologists, and epidemiologists. Systematic evidence-based reviews were performed based upon relevant clinical questions with respect to patient-important outcomes.

RESULTS

The guidelines include updated concept of EoE, evaluated information on disease epidemiology, risk factors, associated conditions, and natural history of EoE in children and adults. Diagnostic conditions and criteria, the yield of diagnostic and disease monitoring procedures, and evidence-based statements and recommendation on the utility of the several treatment options for patients EoE are provided. Recommendations on how to choose and implement treatment and long-term management are provided based on expert opinion and best clinical practice.

CONCLUSION

Evidence-based recommendations for EoE diagnosis, treatment modalities, and patients' follow up are proposed in the guideline.

Transient receptor potential vanilloid 4 inhibits mouse colonic motility by activating NO-dependent enteric neurotransmission

Recent studies implicate TRPV4 receptors in visceral pain signaling and intestinal inflammation. Our aim was to evaluate the role of TRPV4 in the control of gastrointestinal (GI) motility and to establish the underlying mechanisms. We used immunohistochemistry and PCR to study TRPV4 expression in the GI tract. The effect of TRPV4 activation on GI motility was characterized using in vitro and in vivo motility assays. Calcium and nitric oxide (NO) imaging were performed to study the intracellular signaling pathways. Finally, TRPV4 expression was examined in the colon of healthy human subjects. We demonstrated that TRPV4 can be found on myenteric neurons of the colon and is co-localized with NO synthase (NOS-1). In vitro, the TRPV4 agonist GSK1016790A reduced colonic contractility and increased inhibitory neurotransmission. In vivo, TRPV4 activation slowed GI motility and reduced stool production in mouse models mimicking pathophysiological conditions. We also showed that TRPV4 activation inhibited GI motility by reducing NO-dependent Ca(2+) release from enteric neurons. In conclusion, TRPV4 is involved in the regulation of GI motility in health and disease.

KEY MESSAGES

• Recent studies implicate TRPV4 in pain signaling and intestinal inflammation. • Our aim was to characterize the role of TRPV4 in the control of GI motility. • We found that TRPV4 activation reduced colonic contractility. • Our studies also showed altered TRPV4 mRNA expression in IBS-C patients. • TRPV4 may be a novel pharmacological target in functional GI diseases.

Inhibiting endocannabinoid biosynthesis: a novel approach to the treatment of constipation

BACKGROUND AND PURPOSE

Endocannabinoids are a family of lipid mediators involved in the regulation of gastrointestinal (GI) motility. The expression, localization and function of their biosynthetic enzymes in the GI tract are not well understood. Here, we examined the expression, localization and function of the enzyme diacylglycerol lipase-α (DAGLα), which is involved in biosynthesis of the endocannabinoid 2-arachidonoylglycerol (2-AG).

EXPERIMENTAL APPROACH

Cannabinoid CB1 receptor-deficient, wild-type control and C3H/HeJ mice, a genetically constipated strain, were used. The distribution of DAGLα in the enteric nervous system was examined by immunohistochemistry. Effects of the DAGL inhibitors, orlistat and OMDM-188 on pharmacologically induced GI hypomotility were assessed by measuring intestinal contractility in vitro and whole gut transit or faecal output in vivo. Endocannabinoid levels were measured by mass spectrometry.

KEY RESULTS

DAGLα was expressed throughout the GI tract. In the intestine, unlike DAGLβ, DAGLα immunoreactivity was prominently expressed in the enteric nervous system. In the myenteric plexus, it was colocalized with the vesicular acetylcholine transporter in cholinergic nerves. In normal mice, inhibiting DAGL reversed both pharmacologically reduced intestinal contractility and pharmacologically prolonged whole gut transit. Moreover, inhibiting DAGL normalized faecal output in constipated C3H/HeJ mice. In colons incubated with scopolamine, 2-AG was elevated while inhibiting DAGL normalized 2-AG levels.

CONCLUSIONS AND IMPLICATIONS

DAGLα was expressed in the enteric nervous system of mice and its inhibition reversed slowed GI motility, intestinal contractility and constipation through 2-AG and CB1 receptor-mediated mechanisms. Our data suggest that DAGLα inhibitors may be promising candidates for the treatment of constipation.

AM841, a covalent cannabinoid ligand, powerfully slows gastrointestinal motility in normal and stressed mice in a peripherally restricted manner

BACKGROUND AND PURPOSE

Cannabinoid (CB) ligands have been demonstrated to have utility as novel therapeutic agents for the treatment of pain, metabolic conditions and gastrointestinal (GI) disorders. However, many of these ligands are centrally active, which limits their usefulness. Here, we examine a unique novel covalent CB receptor ligand, AM841, to assess its potential for use in physiological and pathophysiological in vivo studies.

EXPERIMENTAL APPROACH

The covalent nature of AM841 was determined in vitro using electrophysiological and receptor internalization studies on isolated cultured hippocampal neurons. Mouse models were used for behavioural analysis of analgesia, hypothermia and hypolocomotion. The motility of the small and large intestine was assessed in vivo under normal conditions and after acute stress. The brain penetration of AM841 was also determined.

KEY RESULTS

AM841 behaved as an irreversible CB1 receptor agonist in vitro. AM841 potently reduced GI motility through an action on CB1 receptors in the small and large intestine under physiological conditions. AM841 was even more potent under conditions of acute stress and was shown to normalize accelerated GI motility under these conditions. This compound behaved as a peripherally restricted ligand, showing very little brain penetration and no characteristic centrally mediated CB1 receptor-mediated effects (analgesia, hypothermia or hypolocomotion).

CONCLUSIONS AND IMPLICATIONS

AM841, a novel peripherally restricted covalent CB1 receptor ligand that was shown to be remarkably potent, represents a new class of potential therapeutic agents for the treatment of functional GI disorders.

Selective inhibition of FAAH produces antidiarrheal and antinociceptive effect mediated by endocannabinoids and cannabinoid-like fatty acid amides

BACKGROUND

The endogenous cannabinoid system (ECS) plays a crucial role in multiple physiological processes in the central nervous system and in the periphery. The discovery that selective cannabinoid (CB) receptor agonists exert a potent inhibitory action on gastrointestinal (GI) motility and pain has placed the ECS in the center of attention as a possible target for the treatment of functional GI diseases. However, side effects of CB agonists prompted the search for novel therapeutic targets. Here, the effect of PF-3845, a potent and selective fatty acid amide hydrolase (FAAH) inhibitor in the GI tract was investigated.

METHODS

The effect of PF-3845 on GI motility was characterized in vitro and in vivo, using mouse models that mimic physiological and pathophysiological conditions. The antinociceptive action of PF-3845 was evaluated on the basis of behavioral pain models. Endocannabinoid degradation product levels after inhibition of FAAH were quantified using HPLC-MS/MS.

KEY RESULTS

PF-3845 significantly inhibited mouse colonic motility in vitro and in vivo. Selective inhibition of FAAH reversed hypermotility and reduced pain in mouse models mimicking functional GI disorders. The effects of PF-3845 were mediated by endogenous CBs and non-CB lipophilic compounds via classical (CB1) and atypical CB receptors.

CONCLUSIONS & INFERENCES

These data expand our understanding of the ECS function and provide a novel framework for the development of future potential treatments of functional GI disorders.

Eosinophilic colitis is a sporadic self-limited disease of middle-aged people: a population-based study

AIM

Eosinophilic colitis (EC) is a rare manifestation of eosinophilic gastrointestinal disorders. Due to its rarity, little information is available on its natural history.

METHOD

From the single population-based pathology database of the Calgary Health Region (comprising a population of 1.28 million in 2008), cases of EC during the period 1996-2008 were identified. Medical records of all adults diagnosed with EC were identified and the pathology reviewed. The patients were then contacted for follow-up using a standardized questionnaire.

RESULTS

Seven cases of EC (four in women) were identified, with a median follow-up of 45 (23-79) months. The median age at diagnosis was 42 (22-70) years. Symptoms at diagnosis were abdominal pain (86%), nonbloody diarrhoea (57%), bloody diarrhoea (29%) and significant (>10%) weight loss (29%). Three patients gave a history of allergic reactions to drugs and four reported allergy to cows' milk. Endoscopic findings were nonspecific, ranging from oedema to small aphthous ulceration. An eosinophilic infiltrate was identified in the lamina propria in the initial colonic biopsy in all patients. Over the longer term, three patients experienced spontaneous resolution without treatment. Two continued to have mild diarrhoea and abdominal cramps but did not require medical therapy. Two patients required medical treatment by 5-aminosalicylic acid, with one requiring prednisone and azathioprine maintenance therapy.

CONCLUSION

Eosinophilic colitis is a rare mostly self-limiting disease affecting middle-aged adults. It usually has a mild clinical course and drug treatment is not usually necessary. When required, drug treatment follows the standard medication for other inflammatory bowel disease.

Physiology, signaling, and pharmacology of opioid receptors and their ligands in the gastrointestinal tract: current concepts and future perspectives

Opioid receptors are widely distributed in the human body and are crucially involved in numerous physiological processes. These include pain signaling in the central and the peripheral nervous system, reproduction, growth, respiration, and immunological response. Opioid receptors additionally play a major role in the gastrointestinal (GI) tract in physiological and pathophysiological conditions. This review discusses the physiology and pharmacology of the opioid system in the GI tract. We additionally focus on GI disorders and malfunctions, where pathophysiology involves the endogenous opioid system, such as opioid-induced bowel dysfunction, opioid-induced constipation or abdominal pain. Based on recent reports in the field of pharmacology and medicinal chemistry, we will also discuss the opportunities of targeting the opioid system, suggesting future treatment options for functional disorders and inflammatory states of the GI tract.

Endocannabinoid and cannabinoid-like fatty acid amide levels correlate with pain-related symptoms in patients with IBS-D and IBS-C: a pilot study

Aims

Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder, associated with alterations of bowel function, abdominal pain and other symptoms related to the GI tract. Recently the endogenous cannabinoid system (ECS) was shown to be involved in the physiological and pathophysiological control of the GI function. The aim of this pilot study was to investigate whether IBS defining symptoms correlate with changes in endocannabinoids or cannabinoid like fatty acid levels in IBS patients.

Methods

AEA, 2-AG, OEA and PEA plasma levels were determined in diarrhoea-predominant (IBS-D) and constipation-predominant (IBS-C) patients and were compared to healthy subjects, following the establishment of correlations between biolipid contents and disease symptoms. FAAH mRNA levels were evaluated in colonic biopsies from IBS-D and IBS-C patients and matched controls.

Results

Patients with IBS-D had higher levels of 2AG and lower levels of OEA and PEA. In contrast, patients with IBS-C had higher levels of OEA. Multivariate analysis found that lower PEA levels are associated with cramping abdominal pain. FAAH mRNA levels were lower in patients with IBS-C.

Conclusion

IBS subtypes and their symptoms show distinct alterations of endocannabinoid and endocannabinoid-like fatty acid levels. These changes may partially result from reduced FAAH expression. The here reported changes support the notion that the ECS is involved in the pathophysiology of IBS and the development of IBS symptoms.

New neostigmine-based behavioral mouse model of abdominal pain

BACKGROUND

Animal models of visceral pain have gained much attention as an important tool to elucidate the possible mechanisms underlying functional gastrointestinal (GI) disorders. Here we report the development of a new, minimally invasive behavioral model of abdominal pain induced by ip administration of neostigmine in mice.

METHODS

Spontaneous behavioral responses evoked by ip injection of neostigmine were compared to pain-related behaviors induced by acetic acid solution (ip), mustard oil (MO) and capsaicin (both ic). Pain behaviors were quantified by assessment of defined postures (licking of the abdomen, stretching, squashing of the abdomen and abdominal contractions). Neuronal activation of spinal cord was measured by determining the number of c-Fos-positive cells.

RESULTS

Neostigmine (2.5 μg/kg, ip), acetic acid solution (ip), MO and capsaicin (both ic) induced spontaneous behavioral responses in mice, which were blocked by morphine (3 mg/kg, ip), suggesting the involvement of pain signaling pathways. Injection of neostigmine enhanced c-Fos expression in spinal cord neurons.

CONCLUSION

The neostigmine model represents a new minimally invasive mouse model to study visceral pain. Based on the neuronal activation pattern in the spinal cord we suggest that this model may be used to study abdominal pain signaling pathways in the GI tract.

The association between celiac disease and eosinophilic esophagitis in children and adults

Background

An association between eosinophilic esophagitis (EoE) and celiac disease (CD) has been suggested in the literature. Our aim was to confirm and quantify the association between these two diseases.

Methods

All patients in a large Canadian city diagnosed with EoE or CD over a five-year period were identified. Standardized incidence ratios (SIRs) with 95% confidence intervals (CIs) were calculated.

Results

Over the five-year study EoE was diagnosed in 421 patients and CD was diagnosed in 763 patients. The incidence of EoE ranged from 2.1 to 10.7 cases per 100,000 population. The incidence of CD ranged from 10.4 to 15.7 cases per 100,000 population. Among the EoE cohort, 83 (20%) cases of EoE and 245 (32%) cases of CD were diagnosed in pediatric patients. The incidence of EoE in the pediatric subpopulation ranged from 3.7 to 6.9 cases per 100,000 population. The incidence of CD in the pediatric subpopulation ranged from 9.5 to 22.7 cases per 100,000 population. The concomitant diagnosis of both EoE and CD was made in three patients, all of whom were pediatric males. The SIR for EoE in the CD cohort was 48.4 (95% CI = 9.73, 141.41) with a SIR for CD within the paediatric EoE cohort of 75.05 (95% CI = 15.08, 219.28).

Conclusions

This study confirms the association between EoE and CD. However, this association may be limited to pediatrics where the risk of each condition is increased 50 to 75-fold in patients diagnosed with the alternative condition. The concomitant diagnosis of these conditions should be considered in pediatric patients with upper gastrointestinal symptoms.

Transient receptor potential vanilloid 4 blockade protects against experimental colitis in mice: a new strategy for inflammatory bowel diseases treatment?

Recent reports suggested that the activation of Transient Receptor Potential Vanilloid 4 (TRPV4) receptors in the gastrointestinal tract has pro-inflammatory effects. In this study, we demonstrated for the first time that TRPV4 mRNA expression is up-regulated in patients with inflammatory bowel diseases (IBD). Furthermore, selective blockade of TRPV4 in the 2,4,6-trinitrobenzenesulfonic acid animal model alleviates colitis and pain associated with the intestinal inflammation. Our study indicates that TRPV4 may play a role in mechanisms of defense in intestinal inflammation and that TRPV4 may be an attractive target for future systemic or topic anti-inflammatory treatment in patients with IBD.

Brain-Gut Interactions in IBS

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder with an estimated prevalence of 10–20%. Current understanding of the pathophysiology of IBS is incomplete due to the lack of a clearly identified pathological abnormality and due to the lack of reliable biomarkers. Possible mechanisms believed to contribute to IBS development and IBS like symptoms include physical stressors, such as infection or inflammation, psychological, and environmental factors, like anxiety, depression, and significant negative life events. Some of these mechanisms may involve the brain-gut axis (BGA). In this article we review the current knowledge on the possible involvement of the BGA in IBS and discuss new directions for potential future therapies of IBS.

Salvinorin A has antiinflammatory and antinociceptive effects in experimental models of colitis in mice mediated by KOR and CB1 receptors

BACKGROUND

Salvinorin A (SA) has a potent inhibitory action on mouse gastrointestinal (GI) motility and ion transport, mediated primarily by kappa-opioid receptors (KOR). The aim of the present study was to characterize possible antiinflammatory and antinociceptive effects of SA in the GI tract of mice.

METHODS

Colonic damage scores and myeloperoxidase activity were determined after intraperitoneal (i.p.), intracolonic (i.c.), and oral (p.o.) administration of SA using the trinitrobenzene sulfonic acid (TNBS) and dextran sodium sulfate (DSS) models of colitis in mice. Additionally, KOR, cannabinoid (CB)1, and CB2 western blot analysis of colon samples was performed. The antinociceptive effect of SA was examined based on the number of behavioral responses to i.c. instillation of mustard oil (MO).

RESULTS

The i.p. (3 mg/kg, twice daily) and p.o. (10 mg/kg, twice daily) administration of SA significantly attenuated TNBS and DSS colitis in mice. The effect of SA was blocked by KOR antagonist nor-binaltorphimine (10 mg/kg, i.p.). Western blot analysis showed no influence of SA on KOR, CB1, or CB2 levels. SA (3 mg/kg, i.p. and 10 mg/kg, i.c.) significantly decreased the number of pain responses after i.c. instillation of MO in the vehicle- and TNBS-treated mice. The antinociceptive action of SA was blocked by KOR and CB1 antagonists. The analgesic effect of i.c. SA was more potent in TNBS-treated mice compared to controls.

CONCLUSIONS

Our results suggest that the drugs based on the structure of SA have the potential to become valuable antiinflammatory or analgesic therapeutics for the treatment of GI diseases.

Inhibiting fatty acid amide hydrolase normalizes endotoxin-induced enhanced gastrointestinal motility in mice

BACKGROUND AND PURPOSE

Gastrointestinal (GI) motility is regulated in part by fatty acid ethanolamides (FAEs), including the endocannabinoid (EC) anandamide (AEA). The actions of FAEs are terminated by fatty acid amide hydrolase (FAAH). We investigated the actions of the novel FAAH inhibitor AM3506 on normal and enhanced GI motility.

EXPERIMENTAL APPROACH

We examined the effect of AM3506 on electrically-evoked contractility in vitro and GI transit and colonic faecal output in vivo, in normal and FAAH-deficient mice treated with saline or LPS (100 µg·kg(-1), i.p.), in the presence and absence of cannabinoid (CB) receptor antagonists. mRNA expression was measured by quantitative real time-PCR, EC levels by liquid chromatography-MS and FAAH activity by the conversion of [(3)H]-AEA to [(3)H]-ethanolamine in intestinal extracts. FAAH expression was examined by immunohistochemistry.

KEY RESULTS

FAAH was dominantly expressed in the enteric nervous system; its mRNA levels were higher in the ileum than the colon. LPS enhanced ileal contractility in the absence of overt inflammation. AM3506 reversed the enhanced electrically-evoked contractions of the ileum through CB(1) and CB(2) receptors. LPS increased the rate of upper GI transit and faecal output. AM3506 normalized the enhanced GI transit through CB(1) and CB(2) receptors and faecal output through CB(1) receptors. LPS did not increase GI transit in FAAH-deficient mice.

CONCLUSIONS AND IMPLICATIONS

Inhibiting FAAH normalizes various parameters of GI dysmotility in intestinal pathophysiology. Inhibition of FAAH represents a new approach to the treatment of disordered intestinal motility.

Plasticity of mouse enteric synapses mediated through endocannabinoid and purinergic signaling

BACKGROUND

The enteric nervous system (ENS) possesses extensive synaptic connections which integrate information and provide appropriate outputs to coordinate the activity of the gastrointestinal tract. The regulation of enteric synapses is not well understood. Cannabinoid (CB)(1) receptors inhibit the release of acetylcholine (ACh) in the ENS, but their role in the synapse is not understood. We tested the hypothesis that enteric CB(1) receptors provide inhibitory control of excitatory neurotransmission in the ENS.

METHODS

Intracellular microelectrode recordings were obtained from mouse myenteric plexus neurons. Interganglionic fibers were stimulated with a concentric stimulating electrode to elicit synaptic events on to the recorded neuron. Differences between spontaneous and evoked fast synaptic transmission was examined within preparations from CB(1) deficient mice (CB(1)(-/-)) and wild-type (WT) littermate controls.

KEY RESULTS

Cannabinoid receptors were colocalized on terminals expressing the vesicular ACh transporter and the synaptic protein synaptotagmin. A greater proportion of CB(1)(-/-) neurons received spontaneous fast excitatory postsynaptic potentials than neurons from WT preparations. The CB(1) agonist WIN55,212 depressed WT synapses without any effect on CB(1)(-/-) synapses. Synaptic activity in response to depolarization was markedly enhanced at CB(1)(-/-) synapses and after treatment with a CB(1) antagonist in WT preparations. Activity-dependent liberation of a retrograde purine messenger was demonstrated to facilitate synaptic transmission in CB(1)(-/-) mice.

CONCLUSIONS & INFERENCES

Cannabinoid receptors inhibit transmitter release at enteric synapses and depress synaptic strength basally and in an activity-dependent manner. These actions help explain accelerated intestinal transit observed in the absence of CB(1) receptors.

Prednisolone and budesonide for short- and long-term treatment of microscopic colitis: systematic review and meta-analysis

BACKGROUND & AIMS

The incidence of microscopic colitis and its disease burden are increasing, yet there is limited systematic information addressing the use of conventional corticosteroids and budesonide in microscopic colitis. We performed a systematic review and meta-analysis on the short- and long-term efficacy of corticosteroids in treatment of microscopic colitis.

METHODS

Randomized controlled trials that met predetermined selection criteria were included. Articles were identified through MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, proceedings of major gastroenterology meetings, and reference lists of trials and review articles.

RESULTS

Eight randomized trials were identified. A total of 248 patients were randomized to corticosteroid versus placebo. The intervention was budesonide in 7 trials and prednisolone in 1 trial. Budesonide was significantly more effective than placebo for short-term clinical response (risk ratio [RR], 3.07; 95% confidence interval [CI], 2.06-4.57) and long-term clinical response (RR, 3.22; 95% CI, 1.05-9.89). Prednisolone was not superior to placebo for short-term clinical response (RR, 2.00; 95% CI, 0.38-10.58). Histologic improvement was seen with both short- and long-term budesonide (RR, 3.76; 95% CI, 2.00-7.06, and RR, 2.50; 95% CI, 1.25-4.98, respectively). Symptom relapse occurred in 46%-80% of patients within 6 months of treatment cessation. Withdrawal because of adverse effects occurred in 4.4% of patients, with no difference between study groups (P = .55).

CONCLUSIONS

Both short- and long-term treatment with budesonide is effective and well-tolerated for microscopic colitis. However, the rate of symptom relapse once budesonide is discontinued is high. Further studies are needed to determine optimal treatment duration, dose, and withdrawal procedure.

Eosinophilic colitis: epidemiology, clinical features, and current management

Primary eosinophilic gastrointestinal disorders (EGIDs) represent a spectrum of inflammatory gastrointestinal disorders in which eosinophils infiltrate the gut in the absence of known causes for such tissue eosinophilia. EGIDs can be subgrouped as eosinophilic esophagitis (EE), eosinophilic gastroenteritis (EG), and eosinophilic colitis (EC). The least frequent manifestation of EGIDs is EC. EC is a heterogeneous entity with a bimodal age distribution, presenting with either an acute self-limited bloody diarrhea in otherwise healthy infants or as a more chronic relapsing colitis in young adults. The pathophysiology of primary EC appears related to altered hypersensitivity, principally as a food allergy in infants and T lymphocyte-mediated (i.e. non-IgE associated) in young adults. In adults, symptoms include diarrhea, abdominal pain, and weight loss. Endoscopic changes are generally modest, featuring edema and patchy granularity. Although standardized criteria are not yet established, the diagnosis of EC depends on histopathology that identifies an excess of eosinophils. Therapeutic approaches are based on case reports and small case series, as prospective randomized controlled trials are lacking. Eosinophilic colitis in infants is a rather benign, frequently food-related entity and dietary elimination of the aggressor often resolves the disorder within days. Adolescent or older patients require more aggressive medical management including: glucocorticoids, anti-histamines, leukotriene receptors antagonists as well as novel approaches employing biologics that target interleukin-5 (IL-5) and IgE. This review article summarizes the current knowledge of EC, its epidemiology, clinical manifestations, diagnosis, and treatment.

Differential effects of salvinorin A on endotoxin-induced hypermotility and neurogenic ion transport in mouse ileum

BACKGROUND

Salvinorin A (SA) is the principal active ingredient of Salvia divinorum, with an established inhibitory action on gastrointestinal (GI) transit and colonic ion transport in mice. Under normal conditions, the effects of SA are mediated by kappa opioid (KOR) and cannabinoid (CB1 and CB2) receptors. However, the role of SA in pathophysiological conditions remains unresolved. The aim of this study was to characterize the in vitro and in vivo effects of SA on mouse ileum after endotoxin challenge.

METHODS

Changes in GI motility were studied in vitro, using smooth muscle preparations from the mouse ileum. In vivo, the fecal pellet output and small intestinal fluid content were measured. Neurogenic ion transport and intestinal permeability were examined using Ussing chambers. In addition, Western blot analysis of mucosa was performed and plasma nitrite/nitrate levels were determined.

KEY RESULTS

Salvinorin A inhibited endotoxin-induced ileal hypercontractility via KOR, CB1, and CB2 receptors. Neurogenic ion transport, which was significantly reduced after endotoxin challenge, was normalized by SA through a nitric oxide synthase (NOS)-dependent mechanism. Western blot analysis and plasma nitrite/nitrate level quantitation confirmed the involvement of NOS in the regulatory action of SA.

CONCLUSIONS & INFERENCES

This is the first report showing differential effects of SA on motor and secretory activity in mouse GI during endotoxemia. The outcomes of our study imply possible novel applications of SA and its analogs in the treatment of GI disorders.

Eosinophilic colitis: an update on pathophysiology and treatment

BACKGROUND

Primary eosinophilic gastrointestinal disorders, a spectrum of inflammatory conditions, occurs when eosinophils selectively infiltrate the gut in the absence of known causes for such tissue eosinophilia. These may be classified into eosinophilic esophagitis, eosinophilic gastroenteritis and eosinophilic colitis (EC). This review focuses on EC: its pathogenesis, epidemiology, clinical presentation, diagnosis and current approach to treatment.

SOURCES OF DATA

A literature review published in English was performed using Pubmed, Ovid, Google scholar search engines with the following keywords: eosinophilic gastrointestinal disorder, EC, eosinophils, colitis and gastrointestinal.

AREAS OF AGREEMENT

The basis for primary EC appears related to increased sensitivity to allergens, principally as a food allergy in infants and a T lymphocyte-mediated event in adults. Endoscopic changes are generally modest, featuring edema and patchy granularity.

AREAS OF CONTROVERSY

Clear clinical and pathological diagnostic criteria of EC and its management strategy.

GROWING POINTS

Intestinal involvement of EC is primarily mucosal, presenting as a mild self-limited proctitis in infants and self-limited colitis in young adults. Therapeutic approaches based on case reports tend to use either elimination diets to avoid a presumed allergen; agents traditionally used in inflammatory disease or targeted drugs like anti-histamines or leukotriene receptor antagonists.

AREAS TIMELY FOR DEVELOPING RESEARCH

Prospective randomized controlled trials addressing the disease natural history, possible preventive methods and effective medical approach and long-term prognosis are required.

Juvenile polyposis of the stomach--a novel cause of hypergastrinemia

BACKGROUND

A 38-year-old female presented with a 3-year history of postprandial abdominal pain, refractory nausea, vomiting and hematemesis. She appeared malnourished and her symptoms were refractory to previous treatment with acid-suppressive drugs, prokinetics and antiemetics. Her medical history was significant for a diagnosis of juvenile polyposis syndrome at the age of 14 resulting in a transverse colectomy, and a diagnosis of Crohn's disease in her residual colon at the age of 35 resulting in a total colectomy.

INVESTIGATIONS

Physical examination, blood analysis, esophagogastroduodenoscopy with biopsy, abdominal endoscopic ultrasound, abdominal CT scan, MRI, 24 h urine analysis, MIBG scintigraphy, ocreotide scintigraphy, fluorodeoxyglucose-PET scan and genetic testing for defined polyposis syndromes (SMAD4, BMPR1A).

DIAGNOSIS

Juvenile polyposis syndrome with outlet obstruction of the stomach and excessive hypergastrinemia.

MANAGEMENT

Continuous acid-suppressive therapy, prokinetic therapy and total parenteral nutrition. Repetitive endoscopic polypectomy (also known as debulking) was performed twice and was followed by gastrectomy with duodenoesophageal anastomosis.

Differential effects of CB(1) neutral antagonists and inverse agonists on gastrointestinal motility in mice

BACKGROUND

Cannabinoid type 1 (CB(1)) receptors are involved in the regulation of gastrointestinal (GI) motility and secretion. Our aim was to characterize the roles of the CB(1) receptor on GI motility and secretion in vitro and in vivo by using different classes of CB(1) receptor antagonists.

METHODS

Immunohistochemistry was used to examine the localization of CB(1) receptor in the mouse ileum and colon. Organ bath experiments on mouse ileum and in vivo motility testing comprising upper GI transit, colonic expulsion, and whole gut transit were performed to characterize the effects of the inverse agonist/antagonist AM251 and the neutral antagonist AM4113. As a marker of secretory function we measured short circuit current in vitro using Ussing chambers and stool fluid content in vivo in mouse colon. We also assessed colonic epithelial permeability in vitro using FITC-labeled inulin.

KEY RESULTS

In vivo, the inverse agonist AM251 increased upper GI transit and whole gut transit, but it had no effect on colonic expulsion. By contrast, the neutral antagonist AM4113 increased upper GI transit, but unexpectedly reduced both colonic expulsion and whole gut transit at high, but not lower doses.

CONCLUSIONS & INFERENCES

Cannabinoid type 1 receptors regulate small intestinal and colonic motility, but not GI secretion under physiological conditions. Cannabinoid type 1 inverse agonists and CB(1) neutral antagonists have different effects on intestinal motility. The ability of the neutral antagonist not to affect whole gut transit may be important for the future development of CB(1) receptor antagonists as therapeutic agents.

Microscopic colitis -- a common cause of diarrhoea in older adults

Diarrhoeal diseases are common in older populations and often markedly affect their quality of life. Although there are numerous potential causes, microscopic colitis (MC) is increasingly recognised as a major diagnostic entity in older individuals. MC is comprised of two distinct histological forms - collagenous colitis and lymphocytic colitis, both of which frequently occur in older populations. Recent studies suggest that between 10 and 30% of older patients investigated for chronic diarrhoea with an endoscopically normal appearing colon will have MC. It is unclear why MC is more common in older populations, but it is associated with both autoimmune disorders and several drugs that are commonly used by seniors. A definitive diagnosis can only be made with colonic biopsies. Since MC was first described in 1976 and only recently recognised as a common cause of diarrhoea, many practising physicians may not be aware of this entity. In this review, we outline the epidemiology, risk factors associated with MC, its pathophysiology, the approach to diagnosis and the management of these individuals.

Novel endomorphin analogues with antagonist activity at the mu-opioid receptor in the gastrointestinal tract

Opioid bowel dysfunction (OBD) summarizes common adverse side effects of opiate-based management of pain. A promising therapeutic approach to prevent OBD and other opioid-related disorders of the gastrointestinal (GI) tract is the co-administration of opiates with peripherally-restricted mu-opioid receptor (MOR)-selective antagonists. The aim of this study was to investigate the selectivity and efficacy of three novel peptide antagonists: antanal-1, antanal-2, and antanal-2A at MOR in the GI tract in vitro and in vivo. The effects of the antanals on GI motility were studied in vitro, using isolated preparations of mouse ileum and colon and in vivo, by measuring colonic propulsion in mice. Additionally, in vitro stability against enzymatic degradation and blood-brain barrier (BBB) permeability using the hot plate test in mice were examined. The antanals significantly reduced the inhibitory effect of the MOR agonists endomorphin-2, morphine, and loperamide on mouse ileum and colon contractions in vitro and blocked morphine-induced decrease of colonic bead expulsion in vivo. The hot plate test in mice showed that the antagonist activity of all antanals was restricted to the periphery. Antanal-1, antanal-2, and antanal-2A are promising MOR antagonists with limited BBB permeability, which may be developed into future therapeutics of opioid-related GI dysfunction.

Salvinorin A inhibits colonic transit and neurogenic ion transport in mice by activating kappa-opioid and cannabinoid receptors

The major active ingredient of the plant Salvia divinorum, salvinorin A (SA) has been used to treat gastrointestinal (GI) symptoms. As the action of SA on the regulation of colonic function is unknown, our aim was to examine the effects of SA on mouse colonic motility and secretion in vitro and in vivo. The effects of SA on GI motility were studied using isolated preparations of colon, which were compared with preparations from stomach and ileum. Colonic epithelial ion transport was evaluated using Ussing chambers. Additionally, we studied GI motility in vivo by measuring colonic propulsion, gastric emptying, and upper GI transit. Salvinorin A inhibited contractions of the mouse colon, stomach, and ileum in vitro, prolonged colonic propulsion and slowed upper GI transit in vivo. Salvinorin A had no effect on gastric emptying in vivo. Salvinorin A reduced veratridine-, but not forskolin-induced epithelial ion transport. The effects of SA on colonic motility in vitro were mediated by kappa-opioid receptors (KORs) and cannabinoid (CB) receptors, as they were inhibited by the antagonists nor-binaltorphimine (KOR), AM 251 (CB(1) receptor) and AM 630 (CB(2) receptor). However, in the colon in vivo, the effects were largely mediated by KORs. The effects of SA on veratridine-mediated epithelial ion transport were inhibited by nor-binaltorphimine and AM 630. Salvinorin A slows colonic motility in vitro and in vivo and influences neurogenic ion transport. Due to its specific regional action, SA or its derivatives may be useful drugs in the treatment of lower GI disorders associated with increased GI transit and diarrhoea.

Activation of the cannabinoid 2 receptor (CB2) protects against experimental colitis

BACKGROUND

Activation of cannabinoid (CB)(1) receptors results in attenuation of experimental colitis. Our aim was to examine the role of CB(2) receptors in experimental colitis using agonists (JWH133, AM1241) and an antagonist (AM630) in trinitrobenzene sulfonic acid (TNBS)-induced colitis in wildtype and CB(2) receptor-deficient (CB(2) (-/-)) mice.

METHODS

Mice were treated with TNBS to induce colitis and then given intraperitoneal injections of the CB(2) receptor agonists JWH133, AM1241, or the CB(2) receptor antagonist AM630. Additionally, CB(2) (-/-) mice were treated with TNBS and injected with JWH133 or AM1241. Animals were examined 3 days after the induction of colitis. The colons were removed for macroscopic and microscopic evaluation, as well as the determination of myeloperoxidase activity. Quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) for CB(2) receptor was also performed in animals with TNBS and dextran sodium sulfate colitis.

RESULTS

Intracolonic installation of TNBS caused severe colitis. CB(2) mRNA expression was significantly increased during the course of experimental colitis. Three-day treatment with JWH133 or AM1241 significantly reduced colitis; AM630 exacerbated colitis. The effect of JWH133 was abolished when animals were pretreated with AM630. Neither JWH133 nor AM1241 had effects in CB(2) (-/-) mice.

CONCLUSIONS

We show that activation of the CB(2) receptor protects against experimental colitis in mice. Increased expression of CB(2) receptor mRNA and aggravation of colitis by AM630 suggests a role for this receptor in normally limiting the development of colitis. These results support the idea that the CB(2) receptor may be a possible novel therapeutic target in inflammatory bowel disease.

The role of the endocannabinoid system in the pathophysiology and treatment of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a spectrum of disorders characterized by abdominal discomfort and pain, associated with altered bowel habits. Though gut motility, secretion and sensation may be altered in patients with IBS, the pathophysiology of this condition remains to be fully understood. The endocannabinoid system is involved in the regulation of numerous gastrointestinal functions including motility, sensation and secretion under both physiological and pathophysiological conditions. Activation of cannabinoid (CB)(1) and CB(2) receptors under various circumstances reduces motility, limits secretion and decreases hypersensitivity in the gut. Drugs that alter the levels of endocannabinoids in the gut also reduce motility and attenuate inflammation. In this review, we discuss the role of the endocannabinoid system in gastrointestinal physiology. We go on to consider the involvement of the endocannabinoid system in the context of symptoms associated with IBS and a possible role of this system in the pathophysiology and treatment of IBS.

Targeting endocannabinoid degradation protects against experimental colitis in mice: involvement of CB1 and CB2 receptors

The endocannabinoid (EC) system mediates protection against intestinal inflammation. In this study, we investigated the effects of blocking EC degradation or cellular reuptake in experimental colitis in mice. Mice were treated with trinitrobenzene-sulfonic acid in presence and absence of the fatty acid amide hydrolase (FAAH) blocker URB597, the EC membrane transport inhibitor VDM11, and combinations of both. Inflammation was significantly reduced in the presence of URB597, VDM11, or both as evaluated by macroscopic damage score, myeloperoxidase levels, and colon length. These effects were abolished in CB(1)- and CB(2)-receptor-gene-deficient mice. Quantitative reverse transcription polymerase chain reaction after induction of experimental colitis by different pathways showed that expression of FAAH messenger RNA (mRNA) is significantly reduced in different models of inflammation early in the expression of colitis, and these return to control levels as the disease progresses. Genomic DNA from 202 patients with Crohn's disease (CD) and 206 healthy controls was analyzed for the C385A polymorphism in the FAAH gene to address a possible role in humans. In our groups, the C385A polymorphism was equally distributed in patients with CD and healthy controls. In conclusion, drugs targeting EC degradation offer therapeutic potential in the treatment of inflammatory bowel diseases. Furthermore, reduction of FAAH mRNA expression is involved in the pathophysiological response to colitis.

The endocannabinoid system and gut–brain signalling

The endocannabinoid system (ECS) consists of cannabinoid receptors, endogenous ligands and the biosynthetic and metabolic enzymes for their formation and degradation. Within the gastrointestinal (GI) tract, the ECS is involved in the regulation of motility, secretion, sensation, emesis, satiety and inflammation. Recent studies examining the ECS in the gut-brain axis have shed new light on this system and reveal many facets of regulation that are amenable to targeting by pharmacological interventions that may prove valuable for the treatment of GI disorders. In particular, it has been shown that endocannabinoid levels in the brain and gut vary according to states of satiety, and in conditions of diarrhea, emesis and inflammation. The expression of cannabinoid (CB)(1) receptors on vagal afferents is controlled by the states of satiety and by gut peptides such as cholecystokinin and ghrelin. Vagal control of gut motor function and emesis is regulated by endocannabinoids in the brainstem acting on CB(1), CB(2) and transient receptor potential vanilloid (TRPV)-1 receptors. The ECS is involved in the modulation of visceral sensation and likely contributes to effects of stress on GI function. This review examines recent developments in our understanding of the ECS in gut-brain signalling.