Original contributionClinicopathologic and gene expression analysis of initial biopsies from patients with eosinophilic esophagitis refractory to therapy

•We study the clinicopathologic characteristics and gene expression of patients refractory to therapy.•Nonresponders had higher number of intraepithelial eosinophils (66 ± 15) than responders (39 ± 8; P < .0001).•NanoString multiplex gene expression analysis was performed to evaluate 285 inflammatory genes.•Overexpressed genes included ALOX15, CCL26, FCER2, RETNLB, and RNASE2.•RTNLB was the only gene significantly overexpressed in patients who were refractory to therapy versus those who responded favorably (10-fold versus 3-fold; P < .01).

SummarySome patients with eosinophilic esophagitis (EoE) do not respond to therapy. The clinicopathologic characteristics and gene expression profile at time of presentation could help predict response to therapy. Refractory EoE was defined as persistence of symptoms and biopsies with histologic features of EoE after 6 months of therapy with proton pump inhibitors and topical corticosteroids. Initial biopsies from refractory EoE patients (n = 21), responder to therapy (n = 8), patients who relapsed (n = 6), and reflux controls (n = 24) were studied. RNA was isolated from a subset of cases, and gene expression analysis of 285 genes involved in inflammation was performed using NanoString technology. There was no difference in the presenting symptoms among groups. The number of eosinophils/high-power field among nonresponders was higher (66 ± 15) than responders (39 ± 8; P < .0001) and similar to patients who relapsed (62 ± 11). Six genes were expressed by at least 4-fold compared with reflux at a false discovery rate < 0.05, including overexpression of ALOX15, CCL26, FCER2, RTNLB, and RNASE2, and underexpression of DSG1. EoE patients refractory to therapy or who relapsed showed a trend toward higher ALOX15 expression compared with patients with good response to therapy (364.4- and 425-fold change, P = .097 and P = .07). RTNLB was significantly overexpressed in patients who were refractory to therapy versus those who responded favorably (10-fold versus 3-fold; P < .01). In conclusion, the number of eosinophils/high-power field in the initial biopsy inversely correlates with therapy response. Overexpression of RTNLB in refractory-to-therapy patients and overexpression of ALOX15 and CCL26 suggest that they are critical in the EoE pathogenesis.