Food allergy series: Eosinophilic gastrointestinal disease (part 3)
The exact incidence of primary EGID is not known, but it has become an increasingly common diagnosis in the last ten years. EGID has been associated with food allergy and atopic conditions. 70% of patients have a family history of allergies. 50% of the time, EGID is seen without accompanying blood eosinophilia. EGID, like many conditions, is thought to have both an environmental and a genetic component. 10% of patients with EGID have an immediate family member with an EGID. Both inhaled and ingested allergens can be provocative for EGID patients.
Patients suffer from a variety of symptoms, including abdominal pain, GI motility issues, vomiting, diarrhea, dysphagia, microcytic anemia, hypoproteinemia and failure to thrive. Visually, the GI tract can be normal, so multiple biopsies from each segment are crucial for diagnosis. Malabsorption and protein losing enteropathy are often coincident in EGID patients.
EGID patients are particularly sensitive to foods. Eggs, milk and fish are the most common problematic foods for EGID patients. Though food specific IgE is often found in EGID patients, food anaphylaxis is rare in this population. Due to the coexistence of EGID and food specific IgE, it is considered a mixed IgE- cell mediated allergic disorder.
Elimination diets and avoidance of aeroallergens are first line treatments for these conditions. Elemental diet improves symptoms and lowers number of eosinophils in EE patients. Significant histological improvement of esophageal inflammation is documented in more than 70% of patients studied. Complete resolution of eosinophilic gastroenteritis is usually seen when the patient transmissions to an elemental amino acid based diet. Unfortunately, reintroduction of foods typically causes immediate onset of symptoms, and thus tolerance is not usually obtainable.
Steroids are often used for EGID acute management. Topic al steroids are sometimes used long term management when diet restriction has not improved symptoms. When treated with oral steroids for four weeks, decrease in eosinophilic count was seen and 65% of patients had complete resolution of symptoms. However, symptoms returned in most patients when steroids were stopped.
Montelukast blocks the D4 receptor of cysteinyl leukotrienes in eosinophils. Leukotrienes are responsible for eosinophil attraction, constriction of smooth muscle, airway swelling, and mucus hypersecretion. However, when leukotriene levels were measured in biopsies from EGID patients, only eosinophilic gastroenteritis patients showed a statistically significant increase in leukotrienes. Still, patients report symptom improvement for the duration of treatment, with relapse when it is removed.
A pilot study treated four patients with eosinophilic gastroenteritis with one dose of anti-IL-5 antibody, mepolizumab. IL-5, eotaxin, is a molecule released by T cells and mast cells that is critical in eosinophil activation. After treatment, there was a mean decrease of 70% in peripheral eosinophilia and 50-70% decrease in tissue eosinophilia (3 out of 4 patients.) Symptoms improved minimally. One patient had a 43% increase in GI eosinophil count following treatment. Approximately two months after treatment, half of the subjects had a significant increase in peripheral eosinophil counts and worsening of symptoms.
One EE patient received three doses of mepolizumab at four week intervals. This induced a ten fold decrease in mean tissue eosinophils, reduced inflammation and stricture, resulted in cessation of vomiting, and allowed the patient to successfully introduce solids. This result in encouraging, but controlled trials need to be undertaken.
Mast cells are both increased and activated in esophageal biopsies from patients with EGIDs. An association between mast cell numbers and severity of esophageal epithelial hyperplasia and eosinophil count has been recorded. Omalizumab has been observed in some studies to lower eosinophil counts in blood and lungs of asthmatics. Foroughi and colleagues ran a 16 week open label study with omalizumab of nine patients with allergic eosinophilic gastroenteritis, with confusing results. A study using anti-TNF medications did not appear promising.
Mueller, Susanna. Classification of eosinophilic gastrointestinal diseases. Best Practice & Research Clinical Gastroenterology 2008, 22 (3): 425-440.
Spergel, Jonathan, et al. Variation in prevalence, diagnostic criteria, and initial management options for eosinophilic gastrointestinal diseases in the United States. JPGN 2011, 52 (3): 300-306.
Jawairia, Mahreema, et al. Eosinophilic gastrointestinal diseases: review and update. ISRN Gastroenterology (2012).