Eosinophil Associated Proteins and Microbiome Profiling in Adults With Eosinophilic Oesophagitis at a Single UK Tertiary Centre

Eosinophilic oesophagitis (EoE) is a chronic progressive inflammatory condition of the oesophagus first described in 1978 but not recognised as distinct diagnosis until 1993, affecting both children and adults. It is characterised by eosinophilic infiltration of the oesophageal epithelium and can lead to difficulty swallowing, oesophageal strictures, food bolus obstruction, and symptoms mimicking gastro-oesophageal reflux disease (GORD). 23% adults with dysphagia and 50% with food bolus obstruction are diagnosed with EoE, meaning it is a common condition encountered by Gastroenterologists. Recent systematic reviews have estimated that EoE has a pooled prevalence of 28-34 per 100,000 population, but the incidence has risen remarkably over the past four decades.

EoE can occur at any age, with a rising incidence in children and adults aged 30-50 years and studies have shown that it can significantly impact on health related quality of life by impairing social and psychological functioning. It is more common in males and in those with allergic conditions such as asthma, eczema and rhinitis, suggesting a food or aeroallergen trigger. Diagnosis is obtained by gastroscopy with a minimum of six oesophageal biopsies recommended by international guidelines, due to its potentially patchy distribution. Hallmark endoscopic appearances of the oesophagus have been described and include oesophageal rings, longitudinal furrows, oedema, exudate, and narrowing. Oesophageal biopsies must show > 15 eosinophils (eos) per high powered field (HPF) infiltrating the oesophageal mucosa, as to not be mistaken with other conditions such as GORD which may also exhibit eosinophilic infiltration but at lower numbers. Other histological features include eosinophil micro-abscesses, basal zone hyperplasia, dilated intercellular spaces, eosinophil surface layering, papillary elongation and lamina propria fibrosis.

Once a diagnosis has been made, treatment of EoE is with food elimination diets, proton pump inhibitors (PPI), or topical glucocorticoids, such as budesonide orodispersible tablet (BOT). In a small subgroup of patients, immunomodulatory drugs such as azathioprine or 6-mercaptopurine might be required, and research is ongoing into monoclonal antibody therapy. The aim of treatment, as described in recent European and American Gastroenterological Association (AGA) and Joint Task Force on Allergy Immunology Practice Parameters (JTF) guidelines, is to alleviate symptoms, prevent stricture formation and achieve histological remission with < 15 eos/HPF infiltration.

Previous studies have shown that PPI may induce remission in 42% patients. Budesonide orodispersible table (BOT) may induce remission in 85% patients, but can be associated with the side effect of candidiasis in up to 10% patients. An empiric 6-food (dairy, wheat, soy, eggs, nuts, and seafood/shellfish) elimination diet induces histological remission in around 75% of patients, whereas a 4-food elimination diet (dairy, wheat, soy, and egg) induced histological remission in around 50% patients, and a 2-food elimination diet (dairy and wheat) may be effective for 40% patients. Elemental diet (amino acids) induces histological remission in 90% of patients but is impractical and only recommended for consideration after failure of medical therapy or elimination diets. Prolonged avoidance of dietary triggers may lead to drug-free sustained clinical and histological remission. Once a stricture has developed then endoscopic balloon dilatation may be required and can improve dysphagia in up to 75% of adults with oesophageal strictures, and is relatively safe with a perforation rate of only 1%, but has no effect on the underlying inflammatory process.

Systematic review with meta-analysis found no statistical difference between PPI and BOT, however there are few head to head studies comparing the treatments and long term evidence for BOT is still lacking; indicating the need for further prospective studies. European guidelines therefore currently do not favour one treatment over another and state that the choice of therapy should be individually discussed with the patient and may be interchangeable over time. Treatment effectiveness should be assessed with repeat gastroscopy with oesophageal biopsies after 6-12 weeks.