Eosinophilic gastroenteritis

Eosinophils and allergic diseases of the gastrointestinal tract

The association between increased tissue eosinophilia and allergic disease is particularly striking in the case of the gastrointestinal tract. About 80% of individuals with eosinophilic gastrointestinal disorders (EGIDs) are atopic, while half of the patients with gastrointestinal allergy show tissue eosinophilia. The function of eosinophils in gastrointestinal allergic disorders is unclear; however, a proinflammatory action is most likely. Cytokines (interleukins 5 and 3, granulocyte-monocyte colony-stimulating factor) and chemokines (eotaxin, RANTES, etc.) released by Th2 lymphocytes, mast cells and other tissue cells have been identified as major regulators of eosinophil chemotaxis and activation, but a convincing mechanism by which eosinophils are activated in an allergen-dependent manner is still lacking. The diagnostic approach comprises both histological and laboratory methods to assess eosinophilia and eosinophil activation, as well as tools to assess the allergic disease while excluding other gastrointestinal diseases such as food intolerances, infections and tumours. Treatment of allergic EGIDs includes elimination or elemental diets and drug therapy using classical anti-allergic agents such as topical corticosteroids and new approaches such as LTD4 receptor antagonists or antibodies against IL-5 or eotaxin.

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.

A dose-response evaluation of spray-dried yeast cell wall supplementation of diets fed to adult dogs: Effects on nutrient digestibility, immune indices, and fecal microbial populations1

The yeast cell wall (YCW) preparation, Safmannan, was evaluated as a dietary supplement for adult dogs. Using a 5 x 5 Latin square design with 14-d periods, adult dogs cannulated in the terminal ileum were supplemented with 0, 0.05, 0.25, 0.45, or 0.65% YCW based on daily food allowance. Apparent ileal nutrient digestibility responded cubically (P = 0.07 to 0.10) to YCW supplementation. Ileal nutrient digestibility tended (P = 0.09) to be greater with YCW supplementation compared with control. Apparent total tract digestibility responded cubically (P < 0.05) to YCW supplementation. Total white blood cell and eosinophil counts tended (P < 0.09) to decrease quadratically with YCW supplementation, with the lowest counts at the 0.25% supplementation level, whereas monocyte counts decreased (P < 0.05) linearly with YCW supplementation. Serum immunoglobulin A (IgA) concentrations tended (P = 0.09) to respond cubically to YCW, with the lowest value at the 0.25% supplementation level. Ileal IgA tended (P < 0.09) to respond quadratically, with the greatest ileal IgA concentration at 0.25% YCW. Using serial dilution and plating enumeration techniques, fecal Escherichia coli concentrations decreased linearly (P = 0.01) with YCW supplementation, whereas Clostridium perfringens responded cubically (P = 0.09). Cubic trends were noted for E. coli (P = 0.10) and lactobacilli (P = 0.08) concentrations, as evaluated by quantitative PCR analysis. Total fecal DNA was most similar to the control treatment at 0.25% YCW. Although the effects on immunological indices appear limited, our results suggest that YCW supplementation in dogs at less than 1% may affect ileal and total tract nutrient digestibility, and the colonization of the gut by E. coli may be decreased.

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.

Eosinophilic enteritis presenting as intussusception in adult

Eosinophilic gastroenteritis is defined as a disorder that selectively affects the gastrointestinal tract with eosinophil-rich inflammation in the absence of any known causes for eosinophilia. The clinical manifestations vary according to the site of the eosinophilic infiltrated layer of the bowel wall. Eosinophilic enteritis presenting as intussusception in adult has not been previously reported in the literature. Especially, making the diagnosis of intussusception in adults is often difficult due to the variable clinical findings. In our case, the correct diagnosis of intussusception due to eosinophilic enteritis was arrived at rather easily based on the ultrasonography and endoscopic biopsy. The patient was treated with oral prednisolone at 30 mg/day for 7 days, and then the drug was tapered off for 2 months; we didn't perform surgery. He has been asymptomatic for about 1 year after discharge without disease recurrence.

Food allergy in gastroenterologic diseases: Review of literature

Food allergy is a common and increasing problem worldwide. The newly-found knowledge might provide novel experimental strategies, especially for laboratory diagnosis. Approximately 20% of the population alters their diet for a perceived adverse reaction to food, but the application of double-blind placebo-controlled oral food challenge, the “gold standard” for diagnosis of food allergy, shows that questionnaire-based studies overestimate the prevalence of food allergies. The clinical disorders determined by adverse reactions to food can be classified on the basis of immunologic or nonimmunologic mechanisms and the organ system or systems affected. Diagnosis of food allergy is based on clinical history, skin prick tests, and laboratory tests to detect serum-food specific IgE, elimination diets and challenges. The primary therapy for food allergy is to avoid the responsible food. Antihistamines might partially relieve oral allergy syndrome and IgE-mediated skin symptoms, but they do not block systemic reactions. Systemic corticosteroids are generally effective in treating chronic IgE-mediated disorders. Epinephrine is the mainstay of treatment for anaphylaxis. Experimental therapies for IgE-mediated food allergy have been evaluated, such as humanized IgG anti-IgE antibodies and allergen specific immunotherapy.

Gastroduodenal diseases of childhood

PURPOSE OF REVIEW

This paper will review new developments in the etiology and management of gastric and duodenal diseases affecting children.

RECENT FINDINGS

Despite dropping prevalence rates in developed nations, most new Helicobacter pylori infections are primarily acquired during childhood. Resistance to standard triple therapy and falling eradication rates are increasing problems for clinicians, necessitating the study of alternative treatment strategies. Eosinophilic diseases of the gastrointestinal tract are being increasingly recognized. Although population-based epidemiology and the natural history of eosinophilic diseases are not yet fully characterized, biologic therapies are in development for the treatment of these chronic, often refractory, conditions. A recent US National Institutes of Health celiac disease consensus conference suggested that infants' diet constituents and timing of solid food introduction are potential environmental influences in the development of celiac disease.

SUMMARY

New methods of diagnosis and treatment are greatly impacting care of pediatric patients with gastric and duodenal diseases. Less invasive but highly accurate tools for diagnosis are becoming better validated. Early diagnosis and effective intervention in most gastroduodenal disorders of childhood can alter natural history and improve overall quality of life.

Eosinophil Function in Eosinophil-associated Gastrointestinal Disorders

Eosinophil-associated gastrointestinal disorders (EGIDs) are characterized by a rich eosinophilic inflammation of the gastrointestinal tract in the absence of known causes for eosinophilia or other gastrointestinal disorders. These disorders include eosinophilic esophagitis, eosinophilic gastritis, eosinophilic gastroenteritis, eosinophilic enteritis, and eosinophilic colitis, and are being recognized with increasing frequency. Clinical studies suggest that eosinophils have a pathogenic role in EGID; however, the function of eosinophils in these disorders remains an enigma. In this review, we briefly describe the clinical features of EGID of the esophagus, small bowel, and colon. We summarize recent experimental analysis examining the underlying contribution of eosinophils to disease pathogenesis and discuss possible therapeutic approaches for the treatment of these diverse diseases.

Genetically modified plants and food hypersensitivity diseases: usage and implications of experimental models for risk assessment

The recent advances in biotechnology in the plant industry have led to increasing crop production and yield that in turn has increased the usage of genetically modified (GM) food in the human food chain. The usage of GM foods for human consumption has raised a number of fundamental questions including the ability of GM foods to elicit potentially harmful immunological responses, including allergic hypersensitivity. To assess the safety of foods derived from GM plants including allergenic potential, the US FDA, Food and Agriculture Organization of the United Nations (FAO)/World Health Organization (WHO), and the EU have developed approaches for evaluation assessment. One assessment approach that has been a very active area of research and debate is the development and usage of animal models to assess the potential allergenicity of GM foods. A number of specific animal models employing rodents, pigs, and dogs have been developed for allergenicity assessment. However, validation of these models is needed and consideration of the criteria for an appropriate animal model for the assessment of allergenicity in GM plants is required. We have recently employed a BALB/c mouse model to assess the potential allergenicity of GM plants. We have been able to demonstrate that this model is able to detect differences in antigenicity and identify aspects of protein post-translational modifications that can alter antigenicity. Furthermore, this model has also enabled us to examine the usage of GM plants as a therapeutic approach for the treatment of allergic diseases. This review discusses the current approaches to assess the allergenic potential of GM food and particularly focusing on the usage of animal models to determine the potential allergenicity of GM foods and gives an overview of our recent findings and implications of these studies.

Role of selectins in the intestinal epithelial migration of eosinophils

Understanding the mechanisms by which eosinophils migrate into and across the intestinal epithelium can provide alternative therapeutic targets for conditions characterized by eosinophilic cryptitis and crypt abscesses. Eosinophil migration is dependent on adhesion molecules such as selectins. Human eosinophils express L-selectin and P-selectin counterligand P-selectin glycoprotein ligand-1 (PSGL-1). The tetrasaccharide sialyl Lewis(x) (sLe(x)) binds to all three selectins, so compounds that mimic sLe(x), such as TBC1269, are potential antagonists. We hypothesized that eosinophils migrate from the basolateral to the apical surface of intestinal epithelium through the orchestrated effects of selectins. TBC1269 was added to fluorescently labeled HL-60 clone 15 eosinophils as well as human blood eosinophils, in incremental amounts. Subsequently, blocking antibodies toward L-selectin and PSGL-1 were used in a similar manner. HL-60 eosinophils were allowed to migrate into T-84 monolayers. The number of migrated HL-60 cells was calculated by comparing fluorescence with known cell densities. HL-60 and human eosinophils that were undergoing migration were significantly lower in the presence of TBC1269. This effect was concentration dependent, and near complete inhibition of migration was seen at a TBC1269 concentration of 10 mg/mL. In addition, HL-60 eosinophil migration was significantly lower in the presence of the blocking antibodies to PSGL-1 and L-selectin (39.2 and 51.6% inhibition, respectively). Simultaneous blocking of PSGL-1 and L-selectin resulted in inhibition of 76.0% of the migration. The results of this study suggest a major role for selectins in the intestinal epithelial migration of differentiated eosinophils. sLe(x), L-selectin, and the P-selectin counterligand PSGL-1 can be potential therapeutic targets.

Eosinophilic gastroenteritis

Eosinophilic gastroenteritis despite its uncommon occurrence is one of the most important primary eosinophilic gastrointestinal disorders, and most commonly presents with abdominal pain. The terminology is, however, misleading because all levels of the gastrointestinal tract from the esophagus to the rectum may be affected. A history of atopy and allergies is present in 25-75% cases. The heterogeneity in the clinical presentations of EG is determined by the site and depth of eosinophilic infiltration. Eosinophilic intestinal inflammation also occurs secondarily in the gastrointestinal tract in inflammatory bowel disease, autoimmune diseases, as reactions to medications, infections, hypereosinophilia syndrome, and after solid organ transplantation. Recent investigations providing an insight into the pathogenesis of eosinophilic gastroenteritis support a critical role for allergens, eosinophils, Th-2 type cytokines, and eotaxin in mediating eosinophilic inflammation. The diagnosis is confirmed by demonstrating prominent tissue eosinophilia on histopathology. Treatment recommendations based on data extrapolated from retrospective, uncontrolled studies, and expert opinion support the use of restricted diets, corticosteroids, leukotriene receptor antagonists, and mast cell stabilizers. Many unanswered questions remain with regard to the natural history, optimal duration of therapy, safer steroid-sparing long-term treatment agents, and the means of reliable and non-invasive follow-up.

Rebound eosinophilia after treatment of hypereosinophilic syndrome and eosinophilic gastroenteritis with monoclonal anti-IL-5 antibody SCH55700

BACKGROUND

Hypereosinophilic syndrome and eosinophilic gastroenteritis with peripheral eosinophilia are characterized by sustained eosinophilia and eosinophil-mediated tissue damage. Although treatment with the humanized monoclonal anti-IL-5 antibody SCH55700 resulted in improvement of eosinophilia and clinical symptoms in 6 of 8 of patients with hypereosinophilic syndrome or eosinophilic gastroenteritis with peripheral eosinophilia for as long as 12 weeks, eosinophil counts subsequently rose above baseline levels, accompanied by an exacerbation of symptoms.

OBJECTIVE

To identify the mechanism underlying this rebound eosinophilia.

METHODS

Purified eosinophils from patients or normal donors were cultured with IL-5, patient serum, and/or anticytokine antibodies, and eosinophil survival was assessed by flow cytometry. Serum and intracellular cytokine levels were measured by multiplex sandwich ELISA and flow cytometry, respectively.

RESULTS

Before treatment with SCH55700, in vitro eosinophil survival in media and in response to recombinant IL-5 was similar in patients and normal donors. At 1 month posttreatment, the eosinophil survival curves were unchanged in 4 of 5 patients in media and in all 5 patients in response to recombinant IL-5. Normal eosinophil survival was prolonged in cultures containing posttreatment but not pretreatment sera (pretreatment vs posttreatment, 10.74% vs 73.02% live cells; P = .01). This posttreatment serum effect on eosinophil survival was reversed by the addition of the monoclonal anti-IL-5 antibody TRFK5. Although increased levels of serum IL-5 were observed at 1 month compared with 2 to 3 days posttreatment in 5 of 6 patients ( P = .04), intracellular cytokine analysis did not reveal increased production of IL-5 by peripheral blood mononuclear cells.

CONCLUSIONS

The rebound eosinophilia after SCH55700 treatment is a result of a serum factor that enhances eosinophil survival. Reversal of this effect by the addition of antibody to IL-5 suggests that this factor may be IL-5 itself.

Œsophagites à œsinophiles : à propos de trois observations

Eosinophilic esophagitis is a rare entity, characterized by eosinophilic infiltration of the oesophagal mucosae, with no gastroesophageal reflux. Food allergies are often involved. We report 3 paediatric cases of eosinophilic esophagitis, revealed by dysphagia, with or without stricture. Eosinophilic esophagitis is a rare disease, but its frequency is probably underestimated. Symptoms are sometimes unusual. Oesogastroscopy with biopsy is essential for the diagnosis. Food allergies can be involved and must be systematically investigated.

Review article: The eosinophil as a therapeutic target in gastrointestinal disease

Elevated levels of eosinophils in the gastrointestinal tract is a common feature of numerous gastrointestinal disorders including food allergy, parasitic infections, gastro-oesophageal reflux, eosinophilic oesophagitis, eosinophilic gastroenteritis, allergic colitis and inflammatory bowel diseases. Recently, clinical and experimental studies have provided evidence that eosinophils have a critical role in the pathophysiology of eosinophil-associated gastrointestinal disease. Collectively, these studies have provided relevant insight into identifying key targets for therapeutic intervention. The present review describes recent experimental investigations on the role of eosinophils in the clinical manifestations of eosinophil-associated gastrointestinal disease and discusses future therapeutic approaches for the treatment of disease.

Diagnosis and treatment of postprandial nausea, allergy, and eosinophilia

We report a case of a 16-year-old male patient who presented with postprandial fullness and nausea. He had a history of seasonal allergies, asthma, and peripheral eosinophilia. Endoscopy of the stomach with mucosal biopsies revealed predominate eosinophils. A diagnosis of eosinophilic gastroenteritis was made. The patient's disease course and management is described in this article.

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.

Reflux esophagitis: sequelae and differential diagnosis in infants and children including eosinophilic esophagitis

Gastroesophageal reflux disease (GERD) is a common condition in infants and children and has many clinical mimics. Most pediatric pathology departments process many mucosal biopsies from the proximal gastrointestinal tract to evaluate the presence or absence of reflux esophagitis. Since this subject was last reviewed in the 1997 edition of Perspectives in Pediatric Pathology devoted to gastrointestinal diseases in children (Dahms BB. Reflux esophagitis and sequelae in infants and children. In: Dahms BB, Qualman SJ, eds. Gastrointestinal Disease. Perspectives in Pediatric Pathology, vol. 20. Basel: Karger, 1997;14-34), progress in the field has allowed recognition of additional presenting symptoms and treatments of GERD. Histologic criteria for diagnosing reflux esophagitis have not changed. However, the entity of eosinophilic esophagitis has emerged since 1997 and has been defined well enough to allow it to be distinguished from reflux esophagitis, with which it was probably previously confused. Refinements (though not simplification!) in the definition of Barrett esophagus are still in evolution. This review will summarize these newer concepts and briefly review the standards of diagnosis of reflux esophagitis.

Eosinophilic gastroenteritis: clinical experience with 15 patients

AIM

To evaluate the clinic features of eosinophilic gastroenteritis and to examine the diagnosis, treatment, long-term outcome of this disease.

METHODS

Charts with a diagnosis of eosinophilic gastroenteritis from 1984 to 2002 at Mackay Memorial Hospital were reviewed retrospectively. There were 15 patients diagnosed with eosinophilic gastroenteritis. The diagnosis was established in 13 by histologic evaluation of endoscopic biopsy or operative specimen and in 2 by radiologic imaging and the presence of eosinophilic ascites.

RESULTS

All the patients had gastrointestinal symptoms and 12 (80%) had hypereosinophilia (absolute eosinophil count 1,008 to 31,360/cm3). The most common symptoms were abdominal pain and diarrhea. Five of the 15 patients had a history of allergy. Seven patients had involvement of the mucosa, 2 of muscularis, and 6 of subserosa. One with a history of seafood allergy was successfully treated with an elimination diet. Another patient improved spontaneously after fasted for several days. The remaining 13 patients were treated with oral prednisolone, 10 to 40 mg/day initially, which was then tapered. The symptoms in all the patients subsided within two weeks. Eleven of the 15 patients were followed up for more than 12 months (12 to 104 months, mean 48.7), of whom 5 had relapses after discontinuing steroids (13 episodes). Two of these patients required long-term maintenance oral prednisolone (5 to 10 mg/day).

CONCLUSION

Eosinophilic gastroenteritis is a rare condition of unclear etiology characterized by relapses and remissions. Short courses of corticosteroids are the mainstay of treatment, although some patients with relapsing disease require long-term low-dose steroids.

Eosinophilic esophagitis in children and adults

Children with eosinophilic esophagitis, an isolated, severe esophageal eosinophilia, present with symptoms similar to gastroesophageal reflux but do not experience response to aggressive antireflux therapy. Increasingly, eosinophilic esophagitis is considered to be a separate entity from reflux disease. Current theory suggests that the former may be caused by cell-mediated food hypersensitivity or may be a subset of eosinophilic gastroenteritis. Reports support the efficacy of dietary restriction or corticosteroid therapy. Additional research is needed to determine etiology, allow earlier clinical recognition, and improve treatment.

Eosinophilic gastroenteritis: epidemiology, diagnosis and management

Eosinophilic gastroenteritis is a heterogeneous and uncommon disorder characterized by eosinophilic inflammation of the gastrointestinal tissues. The location and depth of infiltration determine its varied manifestations, and the latter is also the basis for the proposed classification into mucosal, muscular and serosal eosinophilic gastroenteritis. Abdominal pain, vomiting, and diarrhea are each present in nearly 50% of the patients, with some overlap. Peripheral eosinophilia is seen in approximately two-thirds of patients with eosinophilic gastroenteritis. It is now clear that eotaxin, a specific eosinophil chemoattractant, plays a pivotal role in the process of eosinophil production. The differential diagnosis of eosinophilic gastroenteritis in children includes parasitic infections, inflammatory bowel disease, connective tissue diseases, some malignancies and adverse effects of drugs. Eosinophilic gastroenteritis itself has been strongly associated with food allergies, and concomitant atopic diseases or a family history of allergies is elicited in about 70% of cases. The pediatric experience is unique with respect to recognition of distinctive entities such as allergic procto-colitis, almost exclusively seen in infants, and eosinophilic esophagitis being increasingly reported among children and young adults. The gold standard for diagnosis, usually demonstrated on endoscopic biopsies, is prominent tissue eosinophilia. However, the diagnosis may be obscured by the patchy nature of the disease, and muscular and serosal eosinophilic gastroenteritis subtypes. In the latter cases, full thickness biopsies would be indicated for a definitive diagnosis. There are many reports of successful treatment of eosinophilic gastroenteritis in children, using a variety of treatment regimens including elimination diets. Corticosteroids remain the most effective agents for controlling symptoms, but unfortunately the relapsing nature of the disease would mandate prolonged corticosteroid use. Reports of favorable responses to new leukotriene inhibitors in patients with eosinophilic gastroenteritis are encouraging; these responses should stimulate future research on the pathophysiology and management of eosinophilic gastroenteritis.

Eosinophil-associated gastrointestinal disorders: a world-wide-web based registry

A world wide web database was established that tracked features of eosinophil-associated gastrointestinal disorders; 80% had coexisting atopic disease, 62% had food sensitization, and 16% had an immediate family member with a similar disorder. Developmental delay, seizure disorders, and congenital anomalies were seen in a proportion of respondents. The world wide web has proven to be an efficient tool to gather patient information, allowing us to define distinguishing features of various eosinophil-associated gastrointestinal disorders and to establish that these disorders have strong genetic and allergic components.

Infiltrating eosinophils and eotaxin: their association with idiopathic eosinophilic esophagitis

BACKGROUND

Idiopathic eosinophilic esophagitis (IEE) is a very rare disease characterized by thickening and eosinophil infiltration of the esophagus. The most potent chemotactic factor for eosinophils is eotaxin, and its pathophysiologic significance in IEE needs to be elucidated.

OBJECTIVE

To study the association between eotaxin and IEE.

METHODS

We examined eotaxin expression in the esophagus of an IEE patient in comparison to controls by immunohistochemistry using a monoclonal antibody for human eotaxin. We also measured the free eotaxin level and the total (free and bound-form) eotaxin level in blood by enzyme-linked immunosorbent assay before and after the initiation of steroid therapy.

RESULTS

Most of the infiltrating eosinophils in the affected esophageal tissue showed immunohistochemical staining with anti-eotaxin antibody. In blood samples, the free eotaxin level was slightly elevated before treatment, whereas the total eotaxin level was within the normal range. Unexpectedly, the total eotaxin level increased dramatically after the initiation of steroid therapy, whereas the increase of free eotaxin was modest.

CONCLUSION

Infiltrating eosinophils that express eotaxin and the changes of blood eotaxin levels during steroid therapy suggest that eotaxin may be associated with IEE.

Eosinophilic gastroenteritis

Eosinophilic gastroenteritis is a rare gastrointestinal (GI) disorder of undetermined cause characterized by infiltration of eosinophils in the GI tract. Eosinophils accumulate in tissues and may release highly cytotoxic granular proteins, which cause severe tissue damage characteristic of eosinophilic gastroenteritis. Eotaxin may play a role in the recruitment of eosinophils into tissue in combination with chemoattractants and cytokines, including interleukin 3 and 5 and granulocyte-macrophage colony-stimulating factor. Food allergy, especially in children, can be a triggering factor, and an amino acid-based diet may be helpful. Accumulation of eosinophils in the gut is a common feature in food-induced GI disorders that can be regulated through a complex molecular network involving Th2 cells, various cytokines, and chemokines. Eosinophilic gastroenteritis has a wide spectrum of clinical presentation depending on the site of involvement. It may be confused with irritable bowel syndrome or dyspepsia and, rarely, mimics pancreatitis or appendicitis. Diagnosis is important and is usually made by a pathologist. Eosinophilic gastroenteritis is a treatable disease; patients generally respond to steroid therapy, although relapse is common. Non-enteric-coated budesonide, a locally acting corticosteroid with little risk of adrenal suppression, may be substituted, although more experience is needed. Promising new drugs for eosinophilic gastroenteritis include montelukast, a selective leukotriene receptor antagonist, and suplaplast tosilate, a selective Th2 cytokine inhibitor with inhibitory effects on allergy-induced eosinophilic infiltration and IgE production. Although it is likely a separate disease, more experience has accumulated, and an elimination or specific amino acid-based diet appears to be helpful in treatment.

Experimental analysis of eosinophil-associated gastrointestinal diseases

Eosinophil infiltration into the gastrointestinal tract occurs in a wide range of diseases. However, the underlying cellular and molecular mechanisms involved in eosinophil migration and the role of eosinophils in disease pathogenesis are largely unknown. Recent studies using experimental models of eosinophil-associated gastrointestinal allergy have revealed differential roles for IL-5 and eotaxin in the modulation of eosinophil accumulation into various regions of the gastrointestinal tract. Furthermore, such studies have revealed a possible role for eosinophils in the pathogenesis of gastrointestinal disorders. The present review describes the clinical manifestations of various eosinophil-associated gastrointestinal disorders and the current understanding of the role of IL-5 and eotaxin in the allergic inflammatory response, and the participation of the eosinophilic granulocyte in the expression of disease.

Eosinophilic esophagitis in children: immunopathological analysis and response to fluticasone propionate

BACKGROUND & AIMS

Eosinophilic esophagitis (EE) shares symptoms with gastroesophageal reflux disease but has distinctive pathologic features and unknown immunopathology. Treatments with antigen restriction or systemic immunosuppression pose problems with compliance and side effects. Topically applied steroids offer an attractive alternative treatment. The aims of this study were to determine the immunopathologic features of EE and the effectiveness of antigen-specific diet restriction (DR) and topical immunosuppression.

METHODS

A prospective trial was conducted examining the impact of DR and swallowed fluticasone propionate (FP) on pediatric patients with EE. Clinicopathologic features, including immunohistochemical analysis of the esophageal mucosa, were measured before and after treatment.

RESULTS

Immunohistochemical analysis of 11 prospectively identified children showed a significantly greater number of mucosal CD3 and CD8 lymphocytes, as well as CD1a antigen-presenting cells compared with normal controls. DR did not induce clinical improvement in any patients, whereas all children who completed treatment with FP had resolution of symptoms. Posttreatment analysis of proximal and distal esophageal mucosa showed a significant reduction in the number of eosinophils, as well as CD3(+) and CD8(+) lymphocytes compared with pretreatment sections.

CONCLUSIONS

EE is characterized by immunologically active esophageal mucosa. FP, not DR, effectively relieves symptoms. FP significantly reduces mucosal inflammation associated with EE.

IL-5 promotes eosinophil trafficking to the esophagus

Eosinophil infiltration into the esophagus occurs in a wide range of diseases; however, the underlying pathophysiological mechanisms involved are largely unknown. We now report that the Th2 cytokine, IL-5, is necessary and sufficient for the induction of eosinophil trafficking to the esophagus. We show that transgenic mice overexpressing IL-5 under the control of a T cell (CD2) or a small intestinal enterocyte (fatty acid-binding protein) promoter have markedly increased eosinophil numbers in the esophagus. For example, esophageal eosinophil levels are 1.9 +/- 0.9 and 121 +/- 14 eosinophils/mm(2) in wild-type and CD2-IL-5-transgenic mice, respectively. Consistent with this effect being mediated by a systemic mechanism, pharmacological administration of IL-5 via a miniosmotic pump in the peritoneal cavity resulted in blood and esophageal eosinophilia. To examine the role of IL-5 in oral Ag-induced esophageal eosinophilia, eosinophilic esophagitis was induced by allergen exposure in IL-5-deficient and wild-type mice. Importantly, IL-5-deficient mice were resistant to eosinophilic esophagitis. Finally, we examined the role of eotaxin when IL-5 was overproduced in vivo. Esophageal eosinophil levels in CD2-IL-5-transgenic mice were found to decrease 15-fold in the absence of the eotaxin gene; however, esophageal eosinophil numbers in eotaxin-deficient IL-5-transgenic mice still remained higher than wild-type mice. In conclusion, these studies demonstrate a central role for IL-5 in inducing eosinophil trafficking to the esophagus.

The use of skin prick tests and patch tests to identify causative foods in eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis is a disease entity in which patients have (1) elevated eosinophils on esophageal biopsy and (2) symptoms of gastroesophageal reflux. The symptoms do not improve on aggressive acid blockade but do improve on elimination diet or corticosteroid treatment, which tentatively links food allergies to this disorder.

OBJECTIVE

The purpose of this study was to identify potential food antigens in eosinophilic esophagitis.

METHODS

Patients with eosinophilic esophagitis were identified by biopsy. Potential food antigens were identified prospectively by skin prick testing and patch testing, which were performed through use of standard methods. Atopic tendencies, demographics, and potential food allergies were identified. Repeat esophageal biopsies were reviewed when possible.

RESULTS

A total of 26 patients (22 male, 4 female) with a biopsied-confirmed diagnosis of eosinophilic esophagitis underwent both skin prick testing and patch testing to identify potential causative foods. Milk and egg were the most common positive foods with skin prick testing. Wheat was the most common positive food with patch testing. The patients were advised to avoid positive foods as identified by skin prick testing and patch testing. In all, 18 patients had resolution of their symptoms, 6 patients had partial improvement, and 2 were lost to follow-up. Overall, after intervention, esophageal eosinophil counts improved from 55.8 to 8.4 eosinophils per high-power field. The foods most commonly identified by patients as causing symptoms were milk and egg.

CONCLUSION

The combination of skin prick testing and patch testing can identify potential causative foods that might contribute to the pathogenesis of eosinophilic esophagitis.

Eosinophilic Gastroenteritis

There are no evidence-based studies of the treatment of patients with eosinophilic gastroenteritis. Treatment decisions depend on experience gained from observations linking causative entities, principal clinical manifestations, and anticipated natural history of the disease. Because clinical symptoms and organ involvement probably vary with etiology, classification as to the likely cause (eg, food allergy or other dietary intolerance, idiosyncratic drug reaction, occult infection, idiopathic) determines the decisions made about dietary, pharmacologic, and surgical treatment. Elimination of foods and the use of elemental diets, corticosteroids, and mast cell inhibitors (eg, cromolyn sodium, ketotifen), alone or in combination, all have their place, depending on the age of the patient, organ involved, clinical presentation, and clinical urgency. Isolated cases are diagnosed only at surgical exploration for acute abdominal catastrophes; in these instances, further therapy depends on whether resection is done, but most patients remain in remission after surgery. Occult parasitism remains an elusive and unrecognized cause of an unknown number of cases, suggesting that empiric antihelminthic therapy should be tried in some patients. Individual reports of success with nonsystemic steroids and leukotriene inhibitors have been published.

Food allergy. Mechanisms, diagnosis, and management in children

We eat approximately two to three tons of food in our lifetime, but most people do not have an adverse reaction to foods. Many people believe that they have an allergic reaction to foods; however, the actual incidence confirmed by history and challenges suggests a prevalence rate closer to 2% to 8% in young infants and less than 2% in adults.

A pathological function for eotaxin and eosinophils in eosinophilic gastrointestinal inflammation

Although eosinophils have been implicated in the pathogenesis of gastrointestinal disorders, their function has not been established. Using a murine model of oral antigen-induced eosinophil-associated gastrointestinal disease, we report the pathological consequences of eosinophilic inflammation and the involvement of eotaxin and eosinophils. Exposure of mice to enteric-coated antigen promotes an extensive T helper 2-associated eosinophilic inflammatory response involving the esophagus, stomach, small intestine and Peyer's patches as well as the development of gastric dysmotility, gastromegaly and cachexia. Electron microscopy shows eosinophils in proximity to damaged axons, which indicated that eosinophils were mediating a pathologic response. In addition, mice deficient in eotaxin have impaired eosinophil recruitment and are protected from gastromegaly and cachexia. These results establish a critical pathological function for eotaxin and eosinophils in gastrointestinal allergic hypersensitivity.

An etiological role for aeroallergens and eosinophils in experimental esophagitis

Eosinophil infiltration into the esophagus is observed in diverse diseases including gastroesophageal reflux and allergic gastroenteritis, but the processes involved are largely unknown. We now report an original model of experimental esophagitis induced by exposure of mice to respiratory allergen. Allergen-challenged mice develop marked levels of esophageal eosinophils, free eosinophil granules, and epithelial cell hyperplasia, features that mimic the human disorders. Interestingly, exposure of mice to oral or intragastric allergen does not promote eosinophilic esophagitis, indicating that hypersensitivity in the esophagus occurs with simultaneous development of pulmonary inflammation. Furthermore, in the absence of eotaxin, eosinophil recruitment is attenuated, whereas in the absence of IL-5, eosinophil accumulation and epithelial hyperplasia are ablated. These results establish a pathophysiological connection between allergic hypersensitivity responses in the lung and esophagus and demonstrate an etiologic role for inhaled allergens and eosinophils in gastrointestinal inflammation.

The immunologic basis for intestinal food allergy

There has been considerable recent broadening of basic concepts of intestinal food allergy, in particular the importance of non-IgE-mediated mechanisms. The traditional emphasis on IgE-mediated allergy now appears inappropriate in light of current studies of the basic mechanisms of oral tolerance to dietary antigen and of increasing recognition of the requirement for early infectious challenge in the prevention of allergic sensitization. This major change in emphasis has been forced both by basic scientific studies and by recognition of novel patterns of food allergic disease within the pediatric population, in which rapid increase in food-allergic sensitization has been noted in the last decade and previously rare phenomena such as multiple food allergies and sensitization of exclusively breast-fed infants to antigens eaten by the mother have become commonplace. It is thus emerging that the possession of exaggerated IgE responses may not be the direct cause of food allergic sensitization but may ensure that such sensitization is clinically obvious. Those without such immediate responses have a complex of symptoms, including diet-responsive eczema and a marked disturbance of intestinal motility. The clear demographic links with socioeconomic privilege and relative protection from gastrointestinal infarctions concord with recent murine data suggesting an obligatory input from innate immune responses to the gut flora in the establishment of oral tolerance.

Corticosteroids in the treatment of gastrointestinal disease

Corticosteroids remain the mainstay of anti-inflammatory and immunosuppressive therapy for many gastrointestinal conditions. We are now starting to understand their mechanism of action and the phenomenon of corticosteroid resistance. Because of the ubiquity of corticosteroid receptors in virtually all cells of the body, side effects of therapy are common and may affect multiple body sites. Newer corticosteroid analogues are being developed to minimize these complications, and concomitant use of other immunomodulatory drugs often facilitates corticosteroid dosage reduction or even withdrawal in chronic inflammatory states.

Update in gastrointestinal allergic diseases

Food allergy or hypersensitivity is defined as an adverse reaction to food protein which is immune mediated. Without standard definitions and reliable tests for many forms of allergic disease of the bowel, studies are difficult to interpret. The proceedings of a recent workshop on the classification of adverse immunologic reactions to foods provide the framework for this review. Recent studies have helped define the clinical spectrum and natural history of IgE and non-IgE-mediated food allergy, and provide insight into underlying pathophysiology and dietary management.

A critical role for eotaxin in experimental oral antigen-induced eosinophilic gastrointestinal allergy

Despite marked advances in the understanding of allergic responses, the mechanisms regulating gastrointestinal allergy are not very well understood. We have developed a model of antigen-induced eosinophil-associated gastrointestinal allergy and characterized the role of eotaxin and IL-5. Challenge of allergen-sensitized mice with oral allergen, in the form of enteric-coated beads, resulted in marked allergen-specific IgG(1) and IgE, Th(2)-type (IL-4 and IL-5) cytokine production, and eosinophil accumulation in the blood and small intestine. In the genetic absence of eotaxin, a chemokine constitutively expressed in the gastrointestinal tract, eosinophil recruitment into the small intestine was ablated, and these mice developed enhanced eosinophil accumulation in the blood compared with wild-type mice. Interestingly, in the absence of IL-5, allergen challenge promoted partial eosinophil accumulation into the small intestine and a decline in circulating eosinophil levels. Collectively, these results establish that the accumulation of gastrointestinal eosinophils is antigen induced, can occur independent of IL-5, and provides a molecular mechanism to explain the dichotomy between peripheral blood and tissue eosinophilia. Furthermore, eotaxin is identified as a critical regulator of antigen-induced eosinophilic inflammation in the gastrointestinal tract.