Pathogenesis and clinical features of eosinophilic esophagitis

Chemokines in eosinophil-associated gastrointestinal disorders

Eosinophil-associated gastrointestinal disorders (EGDs) are characterized by a pronounced cellular inflammation. Recent clinical and experimental investigations have implicated a family of molecules known as chemokines in the regulation of leukocyte recruitment in these diseases. The underlying cellular and molecular mechanisms involved in chemokine-mediated cellular infiltration are largely unknown. In this review, we describe the role of CD4+ T cells and eosinophils in the clinical manifestations of EGDs and discuss the current understanding of the role of chemokines in the recruitment of these cells in the expression of diseases.

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.

Primary eosinophilic esophagitis

Eosinophilic esophagitis is an uncommon pathology that generally affects children with a history of allergies and intrinsic asthma. We present a clinical case of eosinophilic esophagitis in a 16-year-old boy with upper dysphagia for solids since childhood. The analytical study showed only a repeat serum eosinophilia. Barium transit disclosed a reduction in caliber of the whole esophagus. Functional esophageal tests with pH monitoring and manometry were normal. Endoscopy showed a small-diameter esophagus and fibrosis with a very friable mucosa. The histological study of the esophageal biopsies revealed a full thickness major eosinophil infiltration of the esophagus. These findings suggest a differential diagnosis with a great variety of pathologies that can cause similar lesions in the esophagus, especially between primary eosinophilic esophagitis and eosinophilic esophagitis secondary to gastro-esophageal reflux disease (GERD). We implemented medical treatment with oral corticoids and total suppression of allergens from the diet, and the patient was asymptomatic.

Natural history of primary eosinophilic esophagitis: a follow-up of 30 adult patients for up to 11.5 years

BACKGROUND & AIMS

Primary eosinophilic esophagitis is a chronic, increasingly recognized, interleukin 5-driven inflammatory disorder of the esophagus. The leading symptom in adults is uniform attacks of dysphagia, and the established histologic sign is a dense eosinophilic infiltration of the esophageal epithelium. Before this study, the natural course of eosinophilic esophagitis had not been defined and information regarding potential long-term risks was lacking.

METHODS

This prospective case series included 30 adult patients with eosinophilic esophagitis (22 men and 8 women; mean age, 40.6 years) whose diagnosis had been made >1 year before study debut based on typical history, consistent endoscopic abnormalities, and infiltration of the esophageal epithelium with >24 eosinophils/high-power field. After a mean of 7.2 years, patients underwent a comprehensive follow-up examination.

RESULTS

All patients survived the study period in good health and stable nutritional state. Dysphagia persisted in 29 patients, exerting a major negative effect on socioprofessional activities on 1 patient and a minor impact on 15. Attacks of dysphagia were more frequent in patients with blood eosinophilia or pronounced endoscopic alterations. The esophageal eosinophilic infiltration persisted in all symptomatic patients, but cell numbers spontaneously decreased significantly (78.7 vs. 40.3 cells/high-power field). The inflammatory process evoked fibrosis of the esophageal lamina propria but did not spread to the stomach or duodenum. No case evolved to a hypereosinophilic syndrome.

CONCLUSIONS

Eosinophilic esophagitis, a primary and chronic disease restricted to the esophagus, leads to persistent dysphagia and structural esophageal alterations but does not impact the nutritional state. To date, no malignant potential has been associated with this disease.

Intratracheal IL-13 induces eosinophilic esophagitis by an IL-5, eotaxin-1, and STAT6-dependent mechanism

BACKGROUND & AIMS

Eosinophil infiltration into the esophagus occurs in a wide range of diseases; however, the underlying pathophysiologic mechanisms involved are largely unknown. We have previously reported that simultaneous delivery of allergen to the lung and gastrointestinal tract induces experimental eosinophilic esophagitis (EE). We aimed to determine whether delivery of a Th2 cytokine (interleukin [IL]-13) to the lung was sufficient for induction of EE.

METHODS

IL-13 was delivered intratracheally to wild-type, signal transducer and activator of transcription (STAT) 6, eotaxin-1, or IL-5-deficient mice. Eosinophil levels and 5'-bromodeoxyuridine (BrdU) incorporation were examined by immunohistochemical staining.

RESULTS

Intratracheal delivery of IL-13 induced dose-dependent eosinophil accumulation in the esophagus (but not the stomach). In addition, intratracheal IL-13 induced esophageal epithelial hyperplasia. The ability of IL-13 to induce EE was abolished in STAT6-deficient mice. IL-13-induced EE was nearly completely ablated in IL-5-deficient mice (37.3 +/- 11.6 vs. 3.3 +/- 3.2 eosinophils/mm(2) in wild-type and IL-5-deficient mice, respectively). Additionally, IL-13-induced EE was significantly diminished in eotaxin-1-deficient mice (48.7 +/- 10.3 vs. 14.1 +/- 12.5 eosinophils/mm(2) in wild-type and eotaxin-1-deficient mice, respectively).

CONCLUSIONS

IL-13 delivery to the lung induces EE by an IL-5, eotaxin-1, and STAT6-dependent mechanism. These results further establish an intimate connection between respiratory and esophageal inflammation.

Clinical and endoscopic features of eosinophilic esophagitis in adults

BACKGROUND

Eosinophilic esophagitis in adults is regarded as unusual, being diagnosed mostly in young men presenting with dysphagia. Mucosal furrows are a sentinel endoscopic feature. This study examined the demographic and clinical profile of adults with eosinophilic esophagitis seen from 1981 to 2002.

METHODS

All patients from an Australian provincial city (population 198,000) with otherwise unexplained eosinophilic inflammation of the squamous epithelium (>/=30 eosinophils per high-power field) were included in a retrospective review.

RESULTS

A diagnosis of eosinophilic esophagitis was made in 31 patients (24 men, 7 women; mean age 34 years, range 14-77 years). The diagnosis was made in 19 (61%) of the 31 patients during the most recent 2 years (none between 1981 and 1994 vs. 12 between 1995-2000 vs. 19 between 2000-2001). Esophageal mucosal furrows were present in 30 (97%), a finding infrequently recognized before 2001. Dysphagia was documented in 26 (89%). Symptoms had been present for long periods before diagnosis (mean 54 months; range 0-180 months), and diagnosis was delayed in 7 (mean 81 months, range 20-144 months) because sentinel features were overlooked at endoscopy. Strictures, often evident only as a result of mucosal shearing during dilation, were present in 17 (57%). Esophageal dilation preformed in 17 (mean 3.4 dilations per patient, range 1-13) consistently relieved symptoms; tears were recorded in 13 (87%), but no serious complication resulted.

CONCLUSIONS

Eosinophilic esophagitis in adults of all ages is more common than recognized. Mucosal furrows are easily overlooked at endoscopy although this finding is an important clue to diagnosis. Strictures, a frequent consequence, can be safely managed by dilation.

Eosinophilic esophagitis

Since Kelly's article appeared in press in 1995, EoE has become an increasingly recognized body. While isolated case reports suggesting EoE have been printed in the adult literature since 1977, many more reports have been published in the pediatric literature over the past 7 years. Recently, [table: see text] several excellent reviews have been written on the subject of EoE [2,25,59,60]. These reviews coupled with the past reports and increasing incidence of EoE provide a sound background for further research on the etiology, epidemiology and treatment of EoE.

Elemental diet is an effective treatment for eosinophilic esophagitis in children and adolescents

OBJECTIVE

Eosinophilic esophagitis (EoE), a disorder characterized by eosinophilic infiltration of the esophageal mucosa, has been defined in large part through published case reports and series leading to ambiguity in both diagnostic and treatment options. Corticosteroids, cromolyn, and elemental diet have all been reported as successful treatments for EoE. In this study, we sought to accurately define a population of patients with EoE and then assess their response to elemental diet.

METHODS

A series of patients with chronic symptoms of gastroesophageal reflux disease and an isolated esophageal eosinophilia on esophagogastroduodenoscopy (EGD) were identified. Therapy with a proton pump inhibitor was instituted for 3 months, followed by repeat EGD when symptoms persisted. A 24-h pH probe study was performed, and those with significantly abnormal studies were excluded. The remaining patients were diagnosed with EoE and placed on an elemental diet for 1 month, followed by a repeat EGD.

RESULTS

Of 346 patients with chronic gastroesophageal reflux disease symptoms and eosinophils on esophageal biopsy, 51 (14.7%) were ultimately diagnosed with EoE. There was significant improvement in vomiting, abdominal pain, and dysphagia after the elemental diet. The median number of esophageal eosinophils per high-powered field (HPF) decreased from 33.7 before the diet to 1.0 after the diet (p <0.01). The average time to clinical improvement was 8.5 days.

CONCLUSIONS

Elemental diet resulted in striking improvement in both symptoms and histologic evidence of disease in children and adolescents with EoE, as identified by strict diagnostic criteria.

Fragility of the esophageal mucosa: a pathognomonic endoscopic sign of primary eosinophilic esophagitis?

BACKGROUND

Primary eosinophilic esophagitis, a chronic inflammatory disorder of the esophagus, evokes recurrent dysphagia. Endoscopy is often unremarkable, and no consensus exists regarding management of resultant dysphagia. The response of a series of patients with primary eosinophilic esophagitis to dilation is reported together with a description of a possibly pathognomonic sign: fragile esophageal mucosa, for which the term "crêpe-paper" mucosa is introduced.

METHODS

Five men underwent endoscopy because of dysphagia confirmed (clinically, endoscopically, and histologically) to be caused by primary eosinophilic esophagitis and were treated by bouginage.

OBSERVATIONS

All patients had extremely fragile, inelastic, and delicate mucosa, which tore easily even with minor trauma. After the procedure, patients remained asymptomatic for 3 to 24 months.

CONCLUSIONS

Primary eosinophilic esophagitis is characterized by fragile esophageal mucosa that readily tears in response to minor trauma during otherwise uneventful diagnostic endoscopy. This "crêpe-paper" sign may alert endoscopists to the presence of the disease when other mucosal alterations are lacking. Dilation is effective for patients with symptoms with minimal morbidity, despite development of disquieting lesions in response to the procedure.

Eosinophilic Esophagitis

Eosinophilic esophagitis is a disease that has moved from relative obscurity, known to a few pediatricians, to one of emerging interest and attention in both the pediatric and adult literature. In part, this is due to the underrecognition of the disease, its increasing description in adults, and the fact that it may be a great imitator of gastroesophageal reflux disease. Symptoms may be protean including heartburn, dysphagia, nausea, vomiting, and abdominal pain accompanied by a history of atopic illnesses. Similarly, endoscopic and radiographic appearances may vary, ranging from stricture and "ring" formation to a completely normal-appearing esophagus, with diagnosis made only on biopsy sampling throughout the entire esophagus. Because this disease is thought to be allergic in origin, primary therapy is an attempt to identify and exclude possible food allergens through skin testing. Owing to the inability to identify an allergen or, conversely, poor compliance with a diet avoiding multiple food allergens, steroids may be useful in this disease. Strictures often require dilation as well owing to the chronic and fibrotic nature of these lesions.

High-resolution EUS in children with eosinophilic "allergic" esophagitis

BACKGROUND

The pathophysiology of dysphagia associated with eosinophilic esophagitis is unknown. This study investigated possible anatomic alterations in children with eosinophilic esophagitis in comparison with healthy children by using high-resolution EUS to precisely measure individual tissue layers of the esophagus.

METHODS

Children with eosinophilic esophagitis (n = 11) and control children (n = 8) without esophagitis were prospectively evaluated by high-resolution EUS with a 20-MHz catheter US probe during an endoscopic examination. Real-time measurements of the distal esophagus were obtained including the thickness of the total wall, combined mucosa and submucosa, muscularis propria, and circular muscle.

RESULTS

Statistically significant differences were found between patients with eosinophilic esophagitis and control patients for mean values for thickness of the total wall (respectively, 2.8 vs. 2.1 mm; p = 0.004), combined mucosa and submucosa (respectively, 1.6 vs. 1.1 mm; p = 0.001), and muscularis propria (respectively, 1.2 vs. 1.0 mm; p = 0.043). Mean values for circular muscle did not differ between patient groups.

CONCLUSION

High-resolution EUS reveals significant expansion of the esophageal wall and individual tissue layers including the combined mucosa and submucosa, and muscularis propria in children with eosinophilic esophagitis compared with healthy control patients.

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.

Food allergies

Adverse reactions to foods are commonly implicated in the causation of ill health. However, foreign antigens, including food proteins and commensal microbes encountered in the gastrointestinal tract, are usually well tolerated. True food allergies, implying immune-mediated adverse responses to food antigens, do exist, however, and are especially common in infants and young children. Allergic reactions to food manifest clinically in a variety of presentations involving the gastrointestinal, cutaneous, and respiratory systems and in generalized reactions such as anaphylaxis. Both IgE-mediated and non-IgE-mediated immune mechanisms are recognized. Important advances in the clinical features underlying specific food hypersensitivity disorders are reviewed.