Evaluation of tissue eosinophilia in the pouch and afferent limb in patients with restorative proctocolectomy

Background: Although tissue eosinophilia in mucosal biopsy specimens from the ileal pouch in patients treated with restorative proctocolectomy is frequently seen, its clinical significance has not been investigated. The aim of this study was to assess whether tissue eosinophilia was associated with disease status of ileal pouches. Methods: Hematoxylin and eosin slides of pouch and afferent limb biopsy specimens from 106 patients randomly selected from the Pouchitis Database were evaluated by 2 gastrointestinal pathologists. Of 106 patients, 81 had corresponding mucosal biopsy specimens of the afferent limb that were available for review. Tissue eosinophil infiltration was evaluated in a semiquantitative fashion with scores ranging from 0-3. Univariate and multivariate analyses were performed to assess the association between eosinophil scores and demographic, clinical, endoscopic, and histologic features. Results: Multivariate analyses showed that tissue eosinophilia of the pouch and afferent limb was not associated with chronic inflammatory conditions of the pouch and the presence of concurrent autoimmune-mediated disorders. Tissue eosinophil score of the pouch was significantly higher than that in the corresponding afferent limb in the same patient population (P = 0.043). A high tissue eosinophil score in the afferent limb was associated with non-use nonsteroidal antiinflammatory drug use (odds ratio = 3.5; 95% confidence interval [CI]: 1.2, 10.4) and high endoscopic inflammation scores in the afferent limb (odds ratio = 1.6; 95% CI: 1.1, 2.2). Similar associations were not found in pouch biopsy specimens. Conclusions: Tissue eosinophilia in the pouch was more prominent than that in the afferent limb in patients with restorative proctocolectomy. Tissue eosinophilia in the pouch and afferent limb appeared to be associated with different risk factors. These findings suggest that luminal factors in different topographical locations of the pouch may contribute to eosinophil-mediated inflammation at these sites.