Serum Interleukin-17 Evaluation in Patients With Eosinophilic Gastrointestinal Disease

Eosinophilic gastrointestinal disorders or diseases (EGIDs) may result from an abnormal immune-mediated response to food antigens. Activated eosinophils release various mediators with inflammatory properties which may result in tissue and subsequently organ damage. The cytokine milieu of these patients has revealed increased levels of pro-inflammatory cytokines, including interleukin (IL)-17. This study aims to evaluate the potential role of this cytokine in the pathogenesis of EGID. This prospective study was conducted at the Allergy Outpatient Clinic, Mofid Children Hospital, Tehran, Iran from January 2016 to January 2017. In this study, Serum IL-17 was determined in all the patients referred to the Allergy Clinic with a pathologic diagnosis of EGID. The median (minimum and maximum) serum IL-17 level in patients with EGID, gastroesophageal reflux disorder (GERD), and healthy controls were 4.32 (0.00-6.383), 2.82 (0.00-3.231), and 3.6 (0.00-7.165) pg/mL, respectively. The results of the non-parametric analysis revealed no significant difference between the three groups regarding IL-17 (P=0.16). However, by classifying EGID in two separate groups with the involvement of upper (eosinophilic esophagitis and eosinophilic gastritis) and lower (eosinophilic enteritis, eosinophilic colitis) gastrointestinal (GI) tracts, a significant difference in serum IL-17 level became evident (P=0.004). We found a significant relationship between IL-17 and upper GI involvement in EGID.