Filaggrin and Periostin Expression Is Altered in Eosinophilic Esophagitis and Normalized With Treatment.

OBJECTIVES: Previous data have suggested that filaggrin (FLG) and periostin (POSTN) genes may be dysregulated in eosinophilic esophagitis (EoE). We aimed to further evaluate the expression patterns of FLG and POSTN proteins in esophageal tissue samples of patients with EoE, as compared to those of patients with gastroesophageal reflux disease (GERD) and normal controls. METHODS: A total of 61 prospectively collected cases, including 40 children with EoE and 21 children with GERD, and a control group of 14 sex- and age-matched healthy children were enrolled. Patients with EoE were treated with skin testing-driven elimination diet and/or corticosteroids. The immunohistochemical expression of FLG and POSTN was evaluated in esophageal biopsies obtained from patients and controls, and the results were correlated with EoE-related clinicopathological parameters. RESULTS: Positive FLG and negative POSTN staining were observed in all esophageal biopsies from normal controls. In contrast, FLG and POSTN stained negative and positive, respectively, in all pretreatment biopsies obtained from patients with EoE, whereas FLG and POSTN stained positive in 57.1% and 95.2% of GERD cases, respectively (P < 0.001). A statistically significant decrease of the proportion of cases with negative FLG and positive POSTN staining was observed from the first (pretreatment) to the second (post-treatment) biopsy in the subgroup of patients with EoE (P < 0.001 in both correlations). CONCLUSIONS: FLG and POSTN expression may be downregulated and upregulated, respectively, in the esophageal mucosa of patients with active EoE, and these changes may be restored with treatment in a significant percentage of cases.