Peripheral Eosinophils and Eosinophilic Esophagitis

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Eosinophilic esophagitis (EoE) is a chronic inflammatory disease associated with mucosal infiltration of the esophagus. EoE incidence appears to be increasing, especially in children, and repeat esophagogastroduodenoscopy (EGD) often is needed to confirm therapeutic response to EoE (typically topical mucosal steroid therapy or dietary changes directed at preventing allergic disease). Since clinical symptoms of EoE are not a good indicator of clinical response to therapy, one of the current goals in EoE research is to find non-invasive biomarkers to monitor disease activity. In that regard, the blood eosinophil count has the potential to be such a marker

The authors of this study performed a retrospective chart review of all pediatric patients (less than 18 years of age) diagnosed with EoE over a 7-year period. Patients with coexisting GI disease were excluded, and EoE was defined as an eosinophil count greater than or equal to 15 eosinophils per highpower field (HPF) in biopsies in any of 3 regions of the esophagus (lower, mid, upper). All patients in this group had been on a proton pump inhibitor for at least 4 weeks prior to EGD. The primary study endpoint was determination of a possible correlation between absolute peripheral eosinophil count and esophageal eosinophilic infiltration. The secondary study endpoint was to see if esophageal eosinophils correlated with biopsy findings of basilar hyperplasia, spongiosis, and the presence of neutrophils and lymphocytes.

A total of 57 patients with EoE, 91 EGDs, and 279 biopsy specimens were included in the study. The oldest patient in the study was 17.9 years while the youngest patient was 1.6 years. The age of participants ranged from 1.6 years to 17.9 years of age, and white study subjects comprised 80% of the study population. A total of 66 procedures (71%) had biopsies consistent with EoE while the other 29% had less than 15 eosinophils per HPF or had no disease noted on biopsies. A significant correlation was seen between absolute eosinophil counts in blood samples and highest esophageal counts in biopsy specimens (P=0.0009). There was a significant correlation between absolute eosinophil counts in patients with active EoE compared to patients with biopsies showing less than 15 eosinophils per HPF or no eosinophilic infiltration. An absolute eosinophil count less than 500 correlated well with patients with inactive disease although an absolute eosinophil count greater than 500 did not correlate well with active EoE. However, when using a logistic regression model for race, sex, weight, height, and body mass index (BMI), none of these factors correlated with absolute eosinophil counts in relation to EoE activity.

It was noted that 58.1% of patients with EoE had allergic rhinitis, 50.5% of patients had food allergies, 38% had asthma, 29 % had eczema, and 14% had all of these conditions together. The most common symptoms included odynophagia (6.5%), food impaction (7.5%), chest pain (11.8%), nausea (23.7%), gastroesophageal reflux symptoms (24.7%), emesis (24.7%), dysphagia (25.8%), and abdominal pain (33.3%). The most common endoscopic finding in patients with EoE included esophageal furrowing (43%). Basilar hyperplasia, spongiosis, and microabscesses were significantly more common in patients with EoE compared to patients with no EoE although the presence of lymphocytes and neutrophils in biopsies did not differ between groups.

Although absolute eosinophil count may be a marker for inactive EoE which has the potential to be used for disease response, this study showed that it was difficult to correlate such findings with worsening EoE. Basilar hyperplasia, spongiosis, and microabscesses (potential early markers of the development of fibrosis) did seem to correlate with EoE although infiltration of other cell types (neutrophils, lymphocytes) did not. The authors state that the patients with EoE in this study were all treated with swallowed budesonide, and we have no data on other interventions such as swallowed fluticasone or dietary therapy. It appears that absolute eosinophil count is not a good marker for following EoE activity over time.

Choudhury S., Kozielski R., Hua J., Wilding G., Baker S. Do histological features of eosinophilic esophagitis in children correlate with peripheral eosinophils? Journal of Pediatric Gastroenterology and Nutrition 2020; 70: 604-607.

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