Interleukin 3, granulocyte-macrophage colony-stimulating factor, and interleukin 5 in eosinophilic gastroenteritis

Circumferential Stenosis of the Second Part of the Duodenum Caused by Eosinophilic Gastroenteritis

Isolated eosinophilic gastroenteritis (EGE) of the second part of the duodenum is rare. We herein report a case of EGE limited to the second part of the duodenum that caused circumferential stenosis due to massive wall thickening. A boring biopsy was useful to verify the accumulation of eosinophils. Induction of remission by prednisolone was accompanied by a marked reduction in the mRNA expression of interleukin-6, C-C motif chemokine ligand 17 (CCL17), and CCL26 without any reduction in prototypical EGE-associated T helper type 2 cytokines (IL-5, IL-13). Thus, the enhanced expression of IL-6, CCL17, and CCL26 might be involved in the development of EGE in this case.

Immune Activation in Functional Dyspepsia: Bystander Becoming the Suspect

Disorders of gut-brain interaction (DGBI), formerly termed functional gastrointestinal disorders (FGID), are highly prevalent although exact pathophysiological mechanisms remain unclear. Intestinal immune activation has been recognized, but increasing evidence supports a pivotal role for an active inflammatory state in these disorders. In functional dyspepsia (FD), marked eosinophil and mast cell infiltration has been repeatedly demonstrated and associations with symptoms emphasize the relevance of an eosinophil-mast cell axis in FD pathophysiology. In this Review, we highlight the importance of immune activation in DGBI with a focus on FD. We summarize eosinophil biology in both homeostasis and inflammatory processes. The evidence for immune activation in FD is outlined with attention to alterations on both cellular and molecular level, and how these may contribute to FD symptomatology. As DGBI are complex and multifactorial conditions, we shed light on factors associated to, and potentially influencing immune activation, including bidirectional gut-brain interaction, allergy and the microbiota. Crucial studies reveal a therapeutic benefit of treatments targeting immune activation, suggesting that specific anti-inflammatory therapies could offer renewed hope for at least a subset of DGBI patients. Lastly, we explore the future directions for DGBI research that could advance the field. Taken together, emerging evidence supports the recognition of FD as an immune-mediated organic-based disorder, challenging the paradigm of a strictly functional nature.

Role of IL-18-transformed CD274-expressing eosinophils in promoting airway obstruction in experimental asthma

BACKGROUND

IL-5-dependent residential and IL-18-transformed pathogenic eosinophils have been reported; however, the role of IL-18-transformed CD274-expressing pathogenic eosinophils compared to IL-5-generated eosinophils in promoting airway obstruction in asthma has not yet been examined.

METHODS

Eosinophils are detected by tissue anti-MBP and anti-EPX immunostaining, CD274 expression by flow cytometry, and airway resistance using the Buxco FinePointe RC system.

RESULTS

We show that A. fumigatus-challenged wild-type mice, and different gene-deficient mice including naïve CC10-IL-18-transgenic mice, accumulate mostly peribronchial and perivascular CD274-expressing eosinophils except naïve CD2-IL-5-transgenic mice. Additionally, we show that CD2-IL-5 transgenic mice following rIL-18 treatment accumulate high number of CD274-expressing perivascular and peribronchial eosinophils with induced collagen, goblet cell hyperplasia and airway resistance compared to saline-challenged CD2-IL5 transgenic mice. Furthermore, we also show that even A. fumigatus-challenged IL-5 ^-/- mice and rIL-18 given ΔdblGATA mice accumulate CD274-expressing eosinophil-associated asthma pathogenesis including airway obstruction. Most importantly, we provide evidence that neutralization of CD274 and IL-18 in A. fumigatus-challenged mice ameliorate experimental asthma. Taken together, the data presented are clinically significant in establishing that anti-IL-18 neutralization is a novel immunotherapy to restrict asthma pathogenesis.

CONCLUSIONS

We demonstrate that IL-18 is critical for inducing asthma pathogenesis, and neutralization of CD274 is a potential immunotherapeutic strategy for asthma.

Pathophysiology of Non-IgE-Mediated Food Allergy

Non-IgE-mediated food allergies are a group of disorders characterized by subacute or chronic inflammatory processes in the gut. Unlike IgE mediated food allergies that may result in multi-organ system anaphylaxis, the non-IgE mediated food allergies primarily affect the gastrointestinal tract. This review outlines the clinical manifestations, epidemiology, pathophysiology, and management of non-IgE-mediated food allergies. An updated literature search of selected non-IgE-mediated food allergies was conducted for this review using PubMed database to the current year (2021). Reviewed disorders include food protein-induced enterocolitis syndrome (FPIES), food-protein enteropathy (FPE), food protein-induced allergic proctocolitis (FPIAP), and eosinophilic gastrointestinal disorders (EGIDs) such as eosinophilic esophagitis (EoE). While extensive gains have been made in understanding FPIES, FPIAP, FPE, and EoE, more information is needed on the pathophysiology of these food allergies. Similarities among them include involvement of innate immunity, T-lymphocyte processes, alteration of the intestinal lumen at the cellular level with the appearance of inflammatory cells and associated histologic changes, and specific cytokine profiles suggesting food-specific, T-cell, and immune-mediated responses. While FPIES and FPIAP typically resolve in early childhood, EGIDs typically do not. Emerging new therapies for EoE offer promise of additional treatment options. Further studies identifying the immunopathogenesis, associated biomarkers, and mechanisms of tolerance are needed to inform prevention, diagnosis and management.

Eosinophilic enteritis with enteroliths: A diagnostic dilemma

Introduction and importance

Eosinophilic gastroenteritis (EG) is a rare disease, characterized by eosinophilic infiltration of different layers of intestinal wall. Thus having a wide spectrum of presentation leading to diagnostic dilemma.

Case presentation

We report a case of 55 years old female who presented with pain in abdomen, constipation, vomiting off and on with passage of stools on alternate days since 6 months. Plain radiographs showed radio-opaque densities in abdomen. Contrast enhanced computed tomography (CECT) of abdomen showed Ileal stricture with dilated proximal bowel loops with enteroliths. Exploratory laparotomy confirmed ileal stricture with thickening of the mesentery and an ileal diverticulum. Resection of ileal stricture was performed. The resected segment contained seven hard, black enteroliths. Histopathology of the resected specimen confirmed EG. Stone analysis showed dense faecal matter with bile salts.

Clinical discussion

EG leads to symptoms ranging from vomiting, abdominal pain, diarrhoea, blood loss in stools, anaemia to malabsorption resulting in diagnostic dilemma. It may cause gastrointestinal obstructive symptoms secondary to stricture, depending upon the predominant layer involved.

Conclusion

The differential diagnosis of EG should always be considered when dealing with gastroenteritis presenting with radio-opaque densities in abdomen.

•

Eosinophilic Gastroenteritis (EG) is a rare disease with a wide spectrum of clinical presentation.

•

Diagnosis of EG is often missed or delayed due to its overlapping findings with other GI disorders.

•

Presentation of Eosinophilic Gastroenteritis with Enterolith is rare.

•

Eosinophilic Gastroenteritis once diagnosed can be treated medically.

•

However, once stricture or enteroliths are formed or there is intestinal obstruction, surgery is the mainstay of treatment.

Functional Dyspepsia and Duodenal Eosinophil Count and Degranulation: A Multiethnic US Veteran Cohort Study

BACKGROUND

Duodenal eosinophilia may play a role in functional dyspepsia (FD), but existing study results are conflicted. We investigated the association between duodenal eosinophils (count and degranulation) and FD symptoms, accounting for atopic conditions, medications, and seasonal variations.

METHODS

In a cross-sectional study conducted in the Michael E. DeBakey VA Medical Center in Houston, Texas, we analyzed duodenal histopathology of 436 patient samples from a prospective cohort with a validated symptom survey data and chart reviews. FD was defined using Rome II symptom criteria. Eosinophil count was number per 5 high-power fields (HPF), and eosinophil degranulation was eosinophilic granules in the stroma both determined by two independent investigators.

RESULTS

The study cohort was predominantly male (87.4%) with a mean age of 59.3 (standard deviation (SD) ± 9.8). Mean and median eosinophil counts were 75.5 (± 47.8) and 63 (IQR: 43, 101) per five HPF, respectively. Duodenal eosinophilia (defined as ≥ 63 per 5 HPF) and eosinophil degranulation were present in 50.5% and 23.1% of patient samples, respectively. FD was observed in 178 patients (41.7%), but neither the mean eosinophil count nor duodenal eosinophilia was associated with FD. Eosinophil degranulation was independently associated with FD overall (OR 1.74; 95% CI 1.08, 2.78; p = 0.02) and early satiety (OR 2.04; 95% CI 1.26, 3.30; p = 0.004).

CONCLUSIONS

In this large, ethnically diverse cohort of adult patients, we found no significant association between duodenal eosinophilia and FD. However, the presence of duodenal eosinophilic degranulation, an activated eosinophil marker, was significantly associated with FD, especially early satiety.

An Evaluation of the Fasciola hepatica miRnome Predicts a Targeted Regulation of Mammalian Innate Immune Responses

Understanding mechanisms by which parasitic worms (helminths) control their hosts’ immune responses is critical to the development of effective new disease interventions. Fasciola hepatica, a global scourge of humans and their livestock, suppresses host innate immune responses within hours of infection, ensuring that host protective responses are quickly incapacitated. This allows the parasite to freely migrate from the intestine, through the liver to ultimately reside in the bile duct, where the parasite establishes a chronic infection that is largely tolerated by the host. The recent identification of micro(mi)RNA, small RNAs that regulate gene expression, within the extracellular vesicles secreted by helminths suggest that these non-coding RNAs may have a role in the parasite-host interplay. To date, 77 miRNAs have been identified in F. hepatica comprising primarily of ancient conserved species of miRNAs. We hypothesized that many of these miRNAs are utilized by the parasite to regulate host immune signaling pathways. To test this theory, we first compiled all of the known published F. hepatica miRNAs and critically curated their sequences and annotations. Then with a focus on the miRNAs expressed by the juvenile worms, we predicted gene targets within human innate immune cells. This approach revealed the existence of targets within every immune cell, providing evidence for the universal management of host immunology by this parasite. Notably, there was a high degree of redundancy in the potential for the parasite to regulate the activation of dendritic cells, eosinophils and neutrophils, with multiple miRNAs predicted to act on singular gene targets within these cells. This original exploration of the Fasciola miRnome offers the first molecular insight into mechanisms by which F. hepatica can regulate the host protective immune response.

Fecal Calprotectin as a Useful Non-Invasive Screening Marker for Eosinophilic Gastrointestinal Disorder in Korean Children

BACKGROUND

Eosinophilic gastrointestinal disorder (EoGID) is an emerging disease condition in Korean children, but its diagnosis requires invasive endoscopic biopsies. Fecal calprotectin (FCal) is a noninvasive biomarker for intestinal inflammation to differentiate organic gastrointestinal diseases from functional abdominal pain disorder. This study aimed to evaluate the diagnostic accuracy of FCal and to determine the optimal cutoff to differentiate EoGID from functional abdominal pain disorder.

METHODS

A total of 253 children (122 boys, 131 girls; mean age 12.2 ± 3.6, range 2.9-17.8 years) who underwent endoscopy with biopsies for chronic gastrointestinal symptoms were recruited, except for 38 children diagnosed with inflammatory bowel disease, and divided into EoGID (n = 67) and functional abdominal pain disorder (n = 186). FCal, white blood cell (WBC) counts, eosinophil counts, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) levels were measured in all subjects at initial diagnosis.

RESULTS

FCal levels weakly correlated with WBC (r = 0.127, P = 0.044) and CRP (r = 0.126, P = 0.040) but not with ESR and eosinophil count. FCal levels were significantly higher in the EoGID group than in the functional abdominal pain disorder group (mean 179.5 ± 242.9 mg/kg vs. 44.3 ± 68.1 mg/kg; P < 0.001), while WBC, ESR, CRP, and eosinophil count did not differ between the two groups (all P > 0.05). An optimal cutoff of FCal 73.2 mg/kg distinguished EoGID from functional abdominal pain disorder with a sensitivity of 50.7% and a specificity of 84.6%.

CONCLUSION

FCal is a useful and reliable noninvasive marker for differentiating EoGID from functional abdominal pain disorder in Korean children with chronic gastrointestinal symptoms when optimal cutoffs are applied.

Eosinophilic gastroenteritis: diagnosis and clinical perspectives

Eosinophilic gastroenteritis (EGE) is a digestive disorder in children and adults that is characterized by eosinophilic infiltration in the stomach and intestine. The underlying molecular mechanisms predisposing to this disease are unknown, but it seems that hypersensitivity response plays a major role in its pathogenesis, as many patients have a history of seasonal allergies, food sensitivities, asthma, and eczema. Symptoms and clinical presentations vary, depending on the site and layer of the gastrointestinal wall infiltrated by eosinophils. Laboratory results, radiological findings, and endoscopy can provide important diagnostic evidence for EGE; however, the cornerstone of the diagnosis remains the histological examination of gastric and duodenal specimens for evidence of eosinophilic infiltration (>20 eosinophils per high-power field), and finally clinicians make the diagnosis in correlation with and by exclusion of other disorders associated with eosinophilic infiltration. Although spontaneous remission is reported in around 30%–40% of EGE cases, most patients require ongoing treatment. The management options for this disorder include both dietary and pharmacological approaches, with corticosteroids being the mainstay of therapy and highly effective. The subsequent course is quite variable. Some patients have no recurrences, while a few experience recurrent symptoms during or immediately after corticosteroid interruption. An alternative therapeutic armamentarium includes mast-cell stabilizers, leukotriene antagonists, antihistamines, immunomodulators, and biological agents. In this review, we provide a summary of the different diagnostic tools utilized in practice, as well as the different therapeutic approaches available for EGE management.

Synergy of Interleukin (IL)-5 and IL-18 in eosinophil mediated pathogenesis of allergic diseases

Eosinophils are circulating granulocytes that have pleiotropic effects in response to inflammatory signals in the body. In response to allergens or pathogens, exposure eosinophils are recruited in various organs that execute pathological immune responses. IL-5 plays a key role in the differentiation, development, and survival of eosinophils. Eosinophils are involved in a variety of allergic diseases including asthma, dermatitis and various gastrointestinal disorders (EGID). IL-5 signal transduction involves JAK-STAT-p38MAPK-NFκB activation and executes extracellular matrix remodeling, EMT transition and immune responses in allergic diseases. IL-18 is a classical cytokine also involved in immune responses and has a critical role in inflammasome pathway. We recently identified the IL-18 role in the generation, transformation, and maturation of (CD101+CD274+) pathogenic eosinophils. In, addition, several other cytokines like IL-2, IL-4, IL-13, IL-21, and IL-33 also contribute in advancing eosinophils associated immune responses in innate and adaptive immunity. This review discusses with a major focus (1) Eosinophils and its constituents, (2) Role of IL-5 and IL-18 in eosinophils development, transformation, maturation, signal transduction of IL-5 and IL-18, (3) The role of eosinophils in allergic disorders and (4) The role of several other associated cytokines in promoting eosinophils mediated allergic diseases.

Biological therapies for eosinophilic gastrointestinal diseases

The scientific basis and the clinical application of mAb therapies that target specific immunologic pathways for eosinophilic gastrointestinal diseases are areas of active interest. There is a growing recognition of a subset of patients with eosinophilic esophagitis whose disease does not respond well to topical steroids or elimination diets. In addition, long-term use of corticosteroids presents possible risks that are currently being evaluated. Systemic therapy with a biologic agent offers potential advantages as a global approach that could limit the need for multiple, locally active medical therapies and allergen avoidance. The identification of novel biologic strategies is ongoing, and the recent validation of instruments and outcome measures to assess disease activity has proved essential in demonstrating efficacy. Studies using biologics that target IL-13 pathways in the treatment of eosinophilic esophagitis have demonstrated substantial promise.

Eosinophilic Enteritis: A Delayed Diagnosis

Eosinophilic gastrointestinal disorders are a rare and complex group of disorders that are characterized by eosinophilic infiltration of the gastrointestinal tract. Patients often present with a wide range of signs and symptoms as any length or layer of the GI tract can be involved such as mucosal, muscular, or serosal. As a part of the workup, patients frequently undergo computed tomography scans and multiple endoscopies before the diagnosis is finally made as was true in our case of a 59-year-old male patient presenting with 2 months of nausea, abdominal pain, and weight loss. He underwent esophagogastroduodenoscopies, colonoscopies, video capsule study, and balloon enteroscopy before the diagnosis was confirmed histologically. Endoscopic and radiographic findings can be variable and are usually unpredictable. The diagnosis is confirmed on histopathological examination of biopsies that must show >15-50 eosinophils/high-power field based on the location in the GI tract. In our patient, erythema, scalloping, whitish exudate, and patches of villous blunting were noted in the duodenum to proximal ileum endoscopically with >50 eosinophils/high-power field confirming the diagnosis of eosinophilic enteritis. This class of diseases is often found in patients with a history of allergic disorders suggestive of hypersensitivity in the etiology of the disease although our patient had no such known history. Elimination diets and steroids are the mainstay of therapy and often lead to complete resolution of symptoms as well as endoscopic and radiographic findings in up to 90% of patients as was seen in our patient, although some patients have a chronic remitting course.

Effects of ischemia and reperfusion on eosinophilic accumulation and distribution in mucosa of equine jejunum and colon

OBJECTIVE To evaluate the eosinophilic response in intestinal mucosa of horses with intestinal ischemia and reperfusion or with strangulation of the jejunum or colon. SAMPLE Mucosal samples from horses with naturally occurring strangulation (n = 24 horses) or distention (n = 6) of the jejunum or colon (11), with experimentally induced ischemia and reperfusion of the jejunum (6) or colon (15), or that were euthanized for reasons other than gastrointestinal tract disease (13). PROCEDURES Mucosal samples were collected and grouped by type of intestinal injury. Slides were stained with Luna eosinophil stain and histologically examined to determine eosinophil accumulation and distribution. Number of eosinophils per mm(2) of mucosa was calculated as a measure of eosinophil accumulation. Additionally, mucosa was categorized into 5 regions; the percentage of eosinophils in each of the 5 regions, relative to the total eosinophil count in all regions, was determined. RESULTS Eosinophil migration toward and onto the luminal surface was evident in tissues after ischemia and reperfusion and after naturally occurring strangulating disease of the jejunum and colon, as indicated by a decrease in the number of eosinophils near the muscularis mucosa and an increase in the number of eosinophils on or near the luminal surface. Ischemia alone did not change eosinophil distribution in the jejunum or colon. CONCLUSIONS AND CLINICAL RELEVANCE Eosinophils responded to mucosal damage evoked by ischemia and reperfusion by migration toward and onto the luminal surface. This migration could represent an important component of the inflammatory response to injury in equine gastrointestinal mucosa.

Eosinophilic Gastroenteritis and Colitis: a Comprehensive Review

Eosinophilic gastrointestinal disorders, including eosinophilic esophagitis, gastroenteritis, and colitis, refer to a spectrum of clinical diseases that present with variable degrees of infiltration of the gastrointestinal tract by eosinophils in the absence of other known causes of tissue eosinophilia. Clinical symptoms and laboratory findings are usually non-specific and may or may not be accompanied by peripheral blood eosinophilia. The extent of eosinophilic infiltration of the gastrointestinal wall varies from mucosal to transmural and serosal involvement. Diagnosis requires presence of gastrointestinal symptoms, demonstration of gastrointestinal eosinophilia by biopsy, and exclusion of other known causes of tissue eosinophilia. Many studies have pointed toward the eosinophil as the major offender; however, the exact functional role of the eosinophil in the pathogenesis of eosinophilic gastrointestinal disorders remains unclear. The roles of T-helper-2 cytokines and other mediators, such as eotaxin-1 and interleukin-5, have gained significant importance in the pathobiology of eosinophilic gastrointestinal disorders. Current understanding of treatment is based on case reports and a few case series, as there is a lack of large prospective studies. Steroids are currently the mainstay of therapy, but the roles of other drugs such as leukotriene inhibitors, mast cell stabilizers, interleukin-5 inhibitors, and anti-immunoglobulin E, along with other targets in the immune pathway, are currently being explored.

Eosinophilic Gastroenteritis: An Underdiagnosed Condition

BACKGROUND

Eosinophilic gastroenteritis (EOGE) is a rare idiopathic disease characterized by eosinophil-predominant inflammation of the stomach and/or intestines. Our aims are to determine the epidemiology, clinical features and outcomes of EOGE cases in a tertiary-care hospital.

METHODS

Retrospective cohort study of patients with gastrointestinal eosinophilic infiltration from 2004 through 2014. All relevant specimens were reviewed by an expert pathologist. Significant eosinophilic infiltrate was defined as >25 eosinophils/HPF in the stomach or small intestine and >50 eosinophils/HPF in the colon.

RESULTS

Three hundred and sixty-one charts were reviewed and 13 EOGE cases were identified, including nine adults and four pediatric cases. The majority (78 %) of adult cases were females. Clinical presentation was variable; most patients (62 %) had abdominal pain, followed by diarrhea (31 %) and nausea/vomiting (31 %). Atopy and food allergies were present in 54 and 38 % of patients, respectively. Weight loss and failure to thrive were present only in pediatric cases (50 vs 0 %; P = .01). Most EOGE cases (69 %) had peripheral eosinophilia, which was more prominent in patients with ascites compared to patients without ascites (37.3 ± 25.4 vs 9.3 ± 5.4 %; P = .01). Among patients who had long-term follow-up; 30 % had spontaneous remission, 60 % responded to steroids and/or restriction diet, and 10 % had refractory disease.

CONCLUSION

EOGE is an underdiagnosed condition. In contrast to eosinophilic esophagitis; the disease might be female-predominant in adults. High index of clinical suspicion is required for diagnosis. Further studies about the long-term outcomes and the efficacy of restriction diet in adult patients are required.

A digestive allergic reaction with hypereosinophilia imputable to docetaxel in a breast cancer patient: a case report

Background

Hypereosinophilia, defined by an absolute eosinophil count of more than 1500/mm3, is rarely observed in patients treated for cancer, and rarely imputable to anti-cancer agents. Drug-induced hypereosinophilia usually appears within a few weeks of the start of treatment and resolves after discontinuation of the medication.

We report here a first case of hypereosinophilia with digestive allergic reaction imputable to docetaxel in a woman treated for breast cancer.

Case presentation

This patient, with a history of childhood atopic dermatitis and asthma, underwent surgery for breast lobular carcinoma, followed with chemotherapy including 3 cycles of the FEC100 protocol and 3 cycles of docetaxel. Ten days after the second cycle of docetaxel, she had abdominal pain with diarrhea, which increased after the third cycle of docetaxel at the same dose. The blood eosinophil count increased up to 4685/mm³ at day 92. All biological tests were normal, except elevated seric IgE. The systematic biopsies of the upper and lower digestive tract showed diffuse edema of the lamina propria, lymphocytic infiltrate and CD117-expressing cells both in the epithelium and in the lamina propria. Electron microscopy showed a large number of degranulating mast cells, while the number of tissue eosinophils was small.

The blood eosinophil count decreased after day 96, three months after the last injection of docetaxel. After day 182, the hypereosinophilia and symptoms resolved. This spontaneous evolution, the history of atopic dermatitis and asthma, and the negativity of all biological tests performed led us to hypothesize a diagnosis of a systemic digestive Type 1 drug-induced hypersensitivity reaction. Using two validated pharmacovigilance scales, we found that docetaxel had the highest imputability score compared to the other drugs.

Conclusion

Recognition of allergic reactions imputable to docetaxel is important because it requires the drug to be discontinued. In the difficult setting of anti-cancer treatment, if reintroduction of the drug is needed, a close collaboration between oncologists, gastroenterologists and allergologists is required.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-2008-0) contains supplementary material, which is available to authorized users.

Eosinophilic gastrointestinal disorders associated with autoimmune connective tissue disease

OBJECTIVES

To determine the clinical and pathological characteristics of eosinophilic gastrointestinal disease (EGID) associated with autoimmune connective tissue disease (CTD).

METHODS

Systematic literature review.

RESULTS

Twenty cases of CTD associated with EGID were identified. Systemic lupus erythematosus was the main EGID-associated CTD (35%), followed by rheumatoid arthritis (20%), systemic sclerosis or inflammatory myopathies (15%, each), and Sjögren's syndrome, scleromyositis or other overlapping connective tissue disease (5%, each). No patient had a history of atopy. In contrast with classical EGID among which eosinophilic esophagitis is the most frequent type, eosinophilic gastritis and/or enteritis represented 95% of cases. Gastrointestinal symptoms were often unspecific. Peripheral eosinophilia was found in 67% of cases. Upper and lower gastrointestinal endoscopy showed abnormal findings in only 40% and 30% of cases, respectively. EGID was confirmed by evidence of digestive eosinophilic infiltration, mainly in mucosal or submucosal layer. In all but one patient, the CTD was diagnosed prior to the occurrence of the EGID. In total, 95% of EGID had a favorable outcome, with corticosteroids being used in almost all cases.

CONCLUSION

Clinicians should consider EGID as a possible diagnosis and perform gastrointestinal tract biopsies in patients with CTD presenting with gastrointestinal symptoms and unexplained eosinophilia. Conversely, more rarely extra-digestive features during follow-up in patients with EGID may lead to a diagnosis of an associated CTD. More research is needed to better understand the underlying pathophysiological processes leading to eosinophilic gastrointestinal infiltration in patients with CTD.

A case of a teenage boy with eosinophilic gastroenteritis with esophageal involvement developing a hemorrhagic duodenal ulcer

A boy in his early teens visited our hospital with chief complaints of hematemesis and tarry stools. Upper gastrointestinal endoscopy identified a hemorrhagic duodenal ulcer, for which hemostasis was performed using a clip. Proton pump inhibitor (PPI) administration diminished the ulcer but relapse occurred after PPI discontinuation. The esophagus showed concentric rings and longitudinal linear furrows considered to be characteristic of eosinophilic esophagitis. Biopsies of the duodenal ulcer and the esophagus revealed marked infiltration of eosinophils, leading to a diagnosis of eosinophilic gastroenteritis with esophageal involvement. Steroid treatment was initiated, and the duodenal ulcer and esophagitis resolved. Endoscopic findings characteristic of eosinophilic esophagitis were key to the diagnosis of eosinophilic gastroenteritis.

An Atypical Case of Eosinophilic Gastroenteritis Presenting as Hypovolemic Shock

Eosinophilic gastroenteritis is an uncommon condition characterized by focal or diffuse infiltration of eosinophils in the gastrointestinal tract in the absence of secondary causes. The pathogenesis of this condition is not well understood and its clinical presentation depends on the segment and layer of the gastrointestinal tract affected. The definition of eosinophilic gastroenteritis may be difficult, as the normal ranges of eosinophil numbers in normal and abnormal gastric and intestinal mucosa are not standardized. We present the case of a 59-year-old male who came to the hospital with hypovolemic shock and lethargy secondary to severe diarrhea. Laboratory analysis was significant for peripheral eosinophilia, and pathology from both the duodenum and colon showed marked eosinophilic infiltration.

Eosinophilic esophagitis in children following cardiac transplantation: association with post-transplant lymphoproliferative disorder and other transplant outcomes

Although cardiac transplantation is life-saving, morbidities from immunosuppression are significant. EoE is a complication of calcineurin inhibitors following liver transplant causing feeding intolerance, weight loss, vomiting, and dysphagia. There are limited reports of EoE following heart transplantation. We performed a retrospective single-center review of pediatric cardiac transplant patients from 2000 to 2010. A case-control analysis of patients with and without EoE was performed evaluating heart transplantation outcomes such as rates of rejection, CAV, PTLD, and graft loss. Eighty-six transplants were performed in 84 patients; 34 (40%) underwent diagnostic endoscopy, and 10 (12%) had EoE. Median time to diagnosis of EoE was 3.7 yr (IQR: 2.0-5.2). There were no differences in demographics or use of induction medications between patients with or without EoE. Patients with EoE had fewer episodes of treated rejection (1.0 vs. 2.5; p = 0.04). Four of 10 (40%) EoE patients had PTLD compared with only 2/24 (8%) of those without EoE (p = 0.048; OR 7.33 [95% CI: 1.1-50.2]). There were no differences in CAV or graft loss between groups. EoE should be considered as a cause of GI symptoms in children after cardiac transplantation and may be associated with fewer rejection episodes and increased rates of PTLD, thus representing a marker of over-immunosuppression.

Eosinophilic esophagitis: an immune-mediated esophageal disease

Eosinophilic esophagitis (EoE) is an emerging disease defined by esophageal dysfunction, by typical endoscopic findings and by abnormal eosinophilic inflammation within the esophagus. Eosinophilic accumulation in the esophagus occurs as a result of esophageal overexpression of pro-inflammatory mediators, including T cells and mast cells, cytokines such as interleukin (IL)-13, IL-5 and IL-15, as well as chemoattractants (eotaxin and transforming growth factor-β1, fibroblast growth factor and the newly characterized gene--thymic stromal lymphopoietin, which is a key regulator of allergic sensitization initiation). The role of allergy, particularly food allergy in EoE is indisputable, as elimination diet is a proven commonly used treatment for the disease. However, unlike classical immediate IgE-mediated reaction to allergen, EoE is associated with an altered immune response, characterized by a combination of IgE-mediated and non-IgE-mediated mechanisms. In this review, we aim to discuss the many typical aspects of EoE as opposed to other entities involving the esophagus, with focusing on the aberrant immune-mediated key players contributing to the pathogenesis of this unique disease.

Eosinophilic gastroenteritis: An unusual type of gastroenteritis

Eosinophilic gastroenteritis (EGE) is a rare disorder characterized by eosinophilic infiltration of the bowel wall with various gastrointestinal manifestations. Till date only 280 cases have been described in the literature. A high index of suspicion, by excluding other causes of peripheral eosinophilia, is a pre requisite for accurate diagnosis. EGE is an uncommon gastrointestinal disease affecting both children and adults. It was first described by Kaijser in 1937. Presentation may vary depending on location as well as depth and extent of bowel wall involvement and usually runs a chronic relapsing course. This condition can respond to low dose steroid therapy, thereby preventing grave complications like ascites and intestinal obstruction that might need surgical intervention. The natural history of EGE has not been well documented. Eosinophilic gastroenteritis is a chronic, waxing and waning condition. Mild and sporadic symptoms can be managed with reassurance and observation, whereas disabling gastrointestinal (GI) symptom flare-ups can often be controlled with oral corticosteroids. When the disease manifests in infancy and specific food sensitization can be identified, the likelihood of disease remission by late childhood is high. GI obstruction is the most common complication. Fatal outcomes are rare.

Eosinophilic gastroenteritis: review of a rare and treatable disease of the gastrointestinal tract

Eosinophilic gastroenteritis is a rare disease of the gastrointestinal tract characterized by crampy abdominal pain, nausea, vomiting, diarrhea, gastrointestinal bleeding, and weight loss associated with peripheral eosinophilia leading to eosinophilic infiltrates in stomach and intestine, usually in a patient with a prior history of atopy. In this article, we describe our encounter with a 59-year-old female presenting with severe abdominal pain, nausea, vomiting, and weight loss with an extensive evaluation including an upper endoscopy with biopsies resulting in a diagnosis of eosinophilic gastroenteritis. The patient was eventually treated with oral prednisone for three weeks with complete resolution of her symptoms.

Peripheral eosinophilia - is it a predictable factor associated with eosinophilic cholecystitis?

BACKGROUNDS/AIMS

The purpose of this study was to evaluate the role of peripheral eosinophilia as a predictable factor associated with Eosinophilic cholecystitis (EC) compared with other forms of cholecystitis in patients who underwent a cholecystectomy.

METHODS

Between January 2001 and May 2011, the histopathologic features of 3,539 cholecystectomy specimens were reviewed retrospectively. EC was diagnosed in 30 specimens (0.84%). Data from 30 consecutive patients with EC (eosinophilic cholecystitis group [E-group]) were compared with a retrospective control group of 60 patients (other cholecystitis group [O-group]) during the same period. The two groups were matched for age, gender, and the presence of cholelithiasis.

RESULTS

The median absolute eosinophil count 1 day post-operatively was 144 cells/mm(3) (range: 9-801 cells/mm(3)) in the E-group and 93 cells/mm(3) (range: 0-490 cells/mm(3)) in the O-group (p=0.036). Pre-operative peripheral eosinophilia was more common in the E-group than the O-group (20% vs. 3.3%, p=0.015). Multivariate analysis revealed that pre-operative peripheral eosinophilia was an independent significant predictable factor associated with EC (odds ratio=7.250, 1.365 <95% confidence interval<38.494, p=0.020).

CONCLUSIONS

In the present study, pre-operative peripheral eosinophilia was shown to be an independent predictable factor associated with EC. Further researches seem to be necessary to confirm this finding.

Gastrointestinal eosinophils in health, disease and functional disorders

Eosinophils are potent innate immune cells that home to the gastrointestinal tract where they participate in host immunity to luminal pathogens, and help to maintain intestinal epithelial homeostasis. However, these cells are now recognized to have key functions in the pathogenesis of numerous other disorders of the gastrointestinal tract, including primary eosinophilic gastrointestinal disease, common functional conditions, such as dyspepsia, and also in gastrointestinal disorders in patients with allergic disease. We are just beginning to understand the potential pathological role of eosinophils in gastrointestinal disease, and it is increasingly likely that gastroenterologists and histopathologists will need to account for the presence of gastrointestinal eosinophils and relate their presence to gastrointestinal symptoms. This Review discusses the role of gastrointestinal eosinophils in health and disease, including their associations with functional and allergic disorders.

Eosinophilic esophagitis

Eosinophilic esophagitis is increasingly recognized in adults. The diagnosis is based on the presence of both typical symptoms and pathologic findings on esophageal biopsy. Patients usually present with dysphagia, food impaction and/or reflux-like symptoms, and biopsy of the esophagus shows more than 15 eosinophils per high-power field. In addition, it is essential to exclude the presence of known causes of tissue eosinophilia such as gastroesophageal reflux disease, infections, malignancy, collagen vascular diseases, hypersensitivity, and inflammatory bowel disease. There are no standardized protocols for the therapy of eosinophilic esophagitis. A variety of therapeutic approaches including acid suppression, dietary modifications, topical corticosteroids and endoscopic dilation can be used alone or in combination.

Eosinophil-associated gastrointestinal disorders with asthma: immunohistochemical analyses

We report 5 patients with eosinophil-associated gastrointestinal disorders (EGIDs) and asthma. All patients developed EGIDs while asthma remained clinically stable. Asthma severity was moderate persistent and severe persistent and 2 patients had intolerance to nonsteroidal anti-inflammatory drugs. By immunohistochemical analysis of the mucosa, eosinophils, macrophages, and T cells were found to be the major infiltrating cells. There was a lesser degree of infiltration of mast cells and B cells but no neutrophils. Compared with normal controls, increased counts of eosinophils and CD8+ T cells were found in the duodenum, and eosinophils, macrophages, and CD4+ T cells in the colon.

Immunoregulatory roles of eosinophils: a new look at a familiar cell

Eosinophils are usually considered as end-stage degranulating effector cells of innate immunity. However, accumulating evidence has revealed additional roles for eosinophils that are immunoregulatory in nature in both the adaptive and innate arms of immunity. Specifically, eosinophils have key immunoregulatory roles as professional antigen-presenting cells and as modulators of CD4(+) T cell, dendritic cell, B cell, mast cell, neutrophil, and basophil functions. This review addresses the emerging immunoregulatory roles of eosinophils with a focus on recent data that support this new paradigm. Recognizing both the effector and immunoregulatory functions of eosinophils will enable a fuller understanding of the roles of eosinophils in allergic airways inflammation and may be pertinent to therapies that target eosinophils both for their acute and ongoing immunomodulatory functions.

General laboratory diagnostics of eosinophilic GI diseases

Eosinophils and gastrointestinal tract interact in an intimate and enigmatic relationship. Under inflammatory conditions, eosinophil infiltration in the gastrointestinal tract is a common feature of numerous eosinophilic gastrointestinal disorders (EGIDs). EGIDs are disorders, for which the diagnosis is relatively difficult. Nevertheless, some common laboratory techniques are currently used for their diagnosis and disease monitoring. Besides eosinophils, mast cells and T cells have also been suggested to play a role in the pathogenesis of these disorders. Here, we review the pathogenesis and common laboratory approaches applied for their diagnosis, in particular eosinophil and mast cell markers.

Oral mucosa lesions in hypereosinophilic syndrome--an update

Hypereosinophilic syndrome (HES) is a rare disorder characterized by persistent and marked eosinophilia. Some HES forms have a poor prognosis, either because of end-organ damage (particularly endomyocardial fibrosis), or because of associated myeloid leukemia or malignant T-cell lymphoma. Oral mucosa ulcerations can be early clinical signs in severe forms. They are discrete, round or oval, sometimes confluent ulcers or erosions, located on non-keratinized, unattached oral mucosa. In the last 15 years a better understanding of eosinophil biology has led to a new clinical classification of HES. The lymphocytic form is characterized by T-lymphocyte clonality, IL-5 production, and a possible progression to T-cell lymphoma. Oral lesions are more frequently associated with the myeloproliferative form, characterized by an increased risk of developing myeloid malignancies and a good response to a recent anti-tyrosine kinase therapy (imatinib mesylate). The target of imatinib is a novel kinase resulting from an 800-kb deletion on chromosome 4. Recently, the resulting FIP1L1-PDGFRalpha fusion gene was characterized as a marker of response to imatinib. Exclusion of other erosive ulcerative oral disease and early recognition of HES in patients with oral ulcerations, and precise characterization of the lymphocytic or myeloproliferative form are therefore important to rapidly initiate an effective therapy.

Eosinophilic gastroenteritis: a review

Eosinophilic gastroenteritis is a rare benign disease characterized by tissue eosinophilic infiltration that may involve several digestive tract layers. Also known as allergic, or eosinophilic allergic, gastroenteropathy, it usually involves the stomach and small intestine: rarely the colon. It may or may not be accompanied by higher counts of eosinophils in the peripheral blood. The main clinical manifestations depend on the site affected. It has been classified according to clinical and pathological features, and the symptoms depend on the patient's immunological response to several cytokines released by eosinophils. Because of lack of understanding of the etiology and triggering factors, treatment is based mainly on corticosteroids; although other drugs acting on the immune system have been tested, the results are not always satisfactory. This review focuses on the epidemiology, pathophysiology, clinical features, and treatment of this hitherto under-diagnosed disease.

Eosinophilia is induced in the colon of Th2-sensitized mice upon exposure to locally expressed antigen

Eosinophilic inflammation is a feature of a variety of gastrointestinal (GI) disorders including eosinophil-associated GI disorder, allergy, inflammatory bowel disease, and parasite infection. Elucidating the mechanisms of eosinophil infiltration into the GI tract is important to the understanding of multiple disease processes. We hypothesize that eosinophilia in the large intestine (colon) can be induced by an antigen in a host that is associated with Th2-skewed antigen-specific immune responses. To investigate the importance of antigenic triggering, we established polarized antigen-specific Th2 type responses in BALB/c mice, using ovalbumin in conjunction with aluminum hydroxide. Upon challenge at the colonic mucosa through transient (3-4 days) expression of the antigen gene encoded in an adenovirus vector, sensitized animals developed significant subepithelial colonic inflammation, characterized by marked eosinophilic infiltration, and the presence of enlarged and increased numbers of lymphoid follicles. The alterations peaked around day 5 and resolved over the next 5-10 days, and no epithelial cell damage was detected through the entire course. Administration of a control (empty) adenovirus vector did not lead to any pathological changes. These data suggest that colonic eosinophilia can be induced by exposure to an antigen associated with preexisting Th2-skewed responses. Thus the model established here may provide a useful tool to study GI and, in particular, colonic inflammation with respect to underlying mechanisms involved in the recruitment and the immediate function of eosinophils.

Quantity and distribution of eosinophils in the gastrointestinal tract of children

There are a lack of data on the quantity and location of eosinophils in the gastrointestinal tract of healthy individuals. Accordingly, we examined gastrointestinal biopsies obtained during endoscopic evaluation of pediatric patients. Biopsies were previously interpreted as having no diagnostic abnormality. The presence of extracellular eosinophil constituents and the quantity of eosinophils in atopic versus nonatopic individuals was determined. In the esophagus, eosinophils were present in only 2.7% of high-power fields (hpf), with a mean value of 0.03+/-0.10 eosinophils/hpf (mean+/-standard deviation) and a maximum of 1 eosinophil/hpf. Examination of the antrum and fundus revealed similar numbers of eosinophils in the lamina propria (1.9+/-1.3 and 2.1+/-2.4 eosinophils/hpf, respectively), with no eosinophils observed in the surface epithelium. In the small intestine, there were 9.6+/-5.3 (maximum, 26 eosinophils/hpf) and 12.4+/-5.4 eosinophils/hpf (maximum, 28 eosinophils/hpf) in the intercryptal lamina propria of the duodenum and ileum, respectively. The number of eosinophils in the surface epithelium and crypt epithelium was minimal. In the large intestine, the highest concentration of eosinophils was observed in the cecum (20.3+/-8.2 eosinophils/hpf; maximum, 50 eosinophils/hpf), and there were lower concentrations in the transverse and sigmoid colon (16.3+/-5.6 and 8.3+/-5.9 eosinophils/hpf, respectively). The percentage of fields demonstrating extracellular eosinophil granules in all gastrointestinal segments was 70% to 93%, and extracellular granules were most numerous at the edge of the biopsy (P<0.05). Atopic and nonatopic patients had comparable numbers of eosinophils. These data establish baseline gastrointestinal eosinophil values in pediatric patients without apparent pathological disease.

Cytokine expression in healthy and inflamed mucosa: probing the role of eosinophils in the digestive tract

BACKGROUND

In eosinophilic esophagitis (EE), the esophagus is infiltrated with activated eosinophils that often evoke tissue damage, but the intestines of these patients remain unaffected. We thus hypothesized that different tissue-dwelling eosinophil populations may coexist: activated eosinophils that infiltrate the esophagus and resting eosinophils that reside in unaffected intestines. We sought to characterize different eosinophil subpopulations by comparing the expression of certain proinflammatory proteins in tissue-dwelling eosinophils at different parts of the gastrointestinal tract.

METHODS

The 8 patients participating included 6 men and 2 women with a previously confirmed diagnosis of EE, whose average age was 39.4 years (range, 20-55 yr) and average disease duration was 13.6 years (range, 2-26 yr). Controls were 3 men and 1 woman, with a mean age of 43.3 years (range, 29-56 yr) with untreated functional dyspepsia who underwent diagnostic esophagogastroduodenoscopy. Six additional individuals having normal blood eosinophils were recruited for cytokine measurements in blood eosinophils. Immunofluorescence and immunoassays charted expression of CD25 and the TH2 cytokines, interleukin (IL)-4, IL-5, IL-10, and IL-13, in esophageal, intestinal, and blood eosinophils from controls and patients.

RESULTS

Controls showed a small but significant proportion of intestinal, but no blood, eosinophils expressing CD25 and IL-13, suggesting physiologic activation occurring in the digestive tract. On the other hand, eosinophils infiltrating the inflamed esophageal mucosa of patients with EE showed strong evidence of activation, with most expressing CD25, IL-4, and IL-13. Moreover, IL-13-positive intestinal eosinophils were increased in patients compared with controls.

CONCLUSIONS

We thus conclude that tissue-dwelling eosinophils show different and distinct cytokine expression patterns under noninflammatory and inflammatory conditions.

In situ eosinophil activation in 26 primary cutaneous T-cell lymphomas with blood eosinophilia

Blood and tissue eosinophils can be associated with Hodgkin and non-Hodgkin lymphomas in that they have prognostic value. Tissue eosinophils in T-cell lymphoma patients with blood eosinophilia have not been systematically assessed. The objective of this research was to study the presence, density, and activation of tissue eosinophils in patients with primary cutaneous T-cell lymphomas (CTCLs) with blood eosinophilia and a possible relationship between features of the disease and prognosis. With skin biopsy specimens from 26 CTCL patients with blood eosinophilia, tissue eosinophils were studied with electron microscopy, extracellular eosinophil peroxidase deposits, and interleukin-5 expression. Tissue eosinophils, found in 22 of 26 cases, were constantly activated. Both density and activation of tissue eosinophils were significantly related to disease progression. The state of activation of tissue eosinophils in CTCL might reflect inflammatory flare-ups associated with aggressive lymphomas. Further studies are needed to confirm the value of eosinophil density as a simple and reliable marker of CTCL progression.

Eosinophilic gastroenteritis associated with systemic lupus erythematosus

Eosinophilic gastroenteritis is an uncommon disease with an obscure etiology, although associations with allergy, the idiopathic hypereosinophilic syndrome, and connective tissue disease have been reported. We present the case of a 37-year-old woman with a history of idiopathic thrombocytopenic purpura who presented with refractory nausea, vomiting, and abdominal pain. Imaging studies were significant for bowel wall thickening and ascites, while laboratory studies revealed a positive antinuclear antibody (ANA), a positive anti-double stranded (DS) DNA antibody, low complement, and proteinuria. Exploratory laparotomy with gastric and small bowel biopsies established the diagnosis of eosinophilic gastroenteritis. In addition, the patient met clinical criteria for the diagnosis of systemic lupus erythematosus. Previous studies have described eosinophilic gastroenteritis in patients with scleroderma, polymyositis, or dermatomyositis. This is the first report to our knowledge of an individual with eosinophilic gastroenteritis and systemic lupus erythematosus.

Prevention of fibrosis in experimental colitis by captopril: the role of tgf-beta1

BACKGROUND & AIMS

There is a body of evidence to suggest that the local activation of angiotensin II (ANG II) plays a pivotal role in fibrogenic response involving the kidney, heart, lung, pancreas and liver. In such conditions, fibrosis is mediated, at least partially, through ANG II induction of the cytokine transforming growth factor-beta1 (TGF-beta1). Both ANG II and TGF-beta1 also seem to be involved in intestinal fibrosis and stenosis, particularly in Crohn's disease. The aim of the present study was, firstly, to determine the effects of the angiotensin-converting enzyme inhibitor, captopril, on colonic fibrosis in experimental colitis in rats and, secondly, to check the role of TGF-beta1 on these effects.

METHODS

Colitis was induced in rats by intracolonic administration of TNBS. Colonic fibrosis was assessed 21 days later by macroscopic and microscopic evaluation. Levels of collagen alpha1 gene expression, hydroxyproline, angiotensin II and TGF-beta1 proteins, and TGF-beta1 mRNA were measured on the colonic tissue.

RESULTS

In chronic colitis, captopril significantly reduced the score of macroscopic and histologic lesions, as well as the colonic tissue levels of collagen alpha1, hydroxyproline, ANG II and TGF-beta1 proteins, and TGF-beta1 mRNA.

CONCLUSIONS

These data demonstrate for the first time that the prophylactic administration of captopril is effective in preventing colonic fibrosis in TNBS-induced colitis. The antifibrotic action of captopril could be due to the blockade of TGFbeta-1 overexpression, and/or to a direct down-regulation of TGFbeta-1 transcript.

Eosinophilia in a patient with cyclical vomiting: a case report

Background

Eosinophilic gastritis is related to eosinophilic gastroenteritis, varying only in regards to the extent of disease and small bowel involvement. Common symptoms reported are similar to our patient's including: abdominal pain, epigastric pain, anorexia, bloating, weight loss, diarrhea, ankle edema, dysphagia, melaena and postprandial nausea and vomiting. Microscopic features of eosinophilic infiltration usually occur in the lamina propria or submucosa with perivascular aggregates. The disease is likely mediated by eosinophils activated by various cytokines and chemokines. Therapy centers around the use of immunosuppressive agents and dietary therapy if food allergy is a factor.

Case presentation

The patient is a 31 year old Caucasian female with a past medical history significant for ulcerative colitis. She presented with recurrent bouts of vomiting, abdominal pain and chest discomfort of 11 months duration. The bouts of vomiting had been reoccurring every 7–10 days, with each episode lasting for 1–3 days. This was associated with extreme weakness and cachexia. Gastric biopsies revealed intense eosinophilic infiltration. The patient responded to glucocorticoids and azathioprine. The differential diagnosis and molecular pathogenesis of eosinophilic gastritis as well as the molecular effects of glucocorticoids in eosinophilic disorders are discussed.

Conclusions

The patient responded to a combination of glucocorticosteroids and azathioprine with decreased eosinophilia and symptoms. It is likely that eosinophil-active cytokines such as interleukin-3 (IL-3), granulocyte macrophage colony stimulating factor (GM-CSF) and IL-5 play pivotal roles in this disease. Chemokines such as eotaxin may be involved in eosinophil recruitment. These mediators are downregulated or inhibited by the use of immunosuppressive medications.

Effects of acetylcysteine and migration of resident eosinophils in an in vitro model of mucosal injury and restitution in equine right dorsal colon

OBJECTIVES

To evaluate the in vitro protective effects of acetylcysteine and response of resident mucosal eosinophils in oxidant-induced injury to tissues of right dorsal colon of horses.

ANIMALS

9 adult horses.

PROCEDURE

Gastrointestinal mucosa was damaged in vitro with 3 mM hypochlorous acid (HOCl), with and without prior exposure to 6mM acetylcysteine. Control tissues were not exposed to HOCl or acetylcysteine. Control and damaged tissues were incubated in Krebs-Ringer-bicarbonate solution and tissue resistance measured during 240 minutes. Tissue permeability to radiolabeled mannitol was also used to assess mucosal barrier integrity. Tissues were examined by light microscopy before and after HOCl exposure and during and after incubation.

RESULTS

Exposure to HOCl caused tissue damage and decreased tissue resistance. Restitution did occur during the incubation period. Eosinophils were located near the muscularis mucosae in freshly harvested tissues and migrated towards the luminal surface in response to HOCl-induced injury. Compared with tissues treated with HOCl without acetylcysteine, pretreatment with acetylcysteine prevented HOCl-induced tissue damage, changes in resistance, and histologically detectable eosinophil migration. The permeability to mannitol increased to the same extent in tissues treated with HOCl alone or with acetylcysteine and HOCl.

CONCLUSIONS AND CLINICAL RELEVANCE

Eosinophils migrated toward the mucosal surface in equine colon in response to oxidant-induced damage in vitro. This novel finding could be relevant to inflammation in equine colon and a pathophysiologic feature of many colonic diseases. Acetylcysteine protected the mucosa against oxidant-induced injury and may be useful as a treatment option for various gastrointestinal tract disorders in horses.

The physiological and pathophysiological roles of eosinophils in the gastrointestinal tract

Eosinophils and the gastrointestinal tract interact in an intimate and enigmatic relationship. Under healthy conditions, the presence of eosinophils is limited almost exclusively to the digestive tract mucosa where they exert several effector and immunoregulatory functions. While their precise function in the gastrointestinal tract is not completely understood, it is likely that, together with different T cell subsets, eosinophils are involved in maintaining the immunologic homeostastis across the mucosal barrier under resting conditions. Eosinophils also play a role in several inflammatory conditions, such as intestinal infections, hypersensitivity reactions, primary eosinophilic inflammations and several other chronic intestinal disorders. Depending on the responsible trigger, their effects may be beneficial or detrimental. Here, we discuss the available information regarding the physiological and pathological functions of eosinophils within the gastrointestinal tract.