Is Use of PPIs Related to Increased Intraepithelial Lymphocytes in the Colon?

Background The use of proton pump inhibitors (PPIs) is thought to increase the incidence of microscopic colitis (MC), although the exact mechanisms are not fully understood. Increased infiltration of intraepithelial lymphocytes (IELs) is a pathologic finding of MC (including collagenous or lymphocytic colitis). Aims We investigated whether PPI use is associated with increased IEL infiltration and inflammation in the lamina propria. Methods We retrospectively reviewed the medical records and histological reports of 78 patients receiving PPIs who had no symptoms of diarrhea, and their age- and gender- matched controls. The levels of IELs and inflammation in the lamina propria were assessed independently by two pathologists using H&E and immunohistochemical staining for CD3 and CD8. Results The IEL count was significantly higher in the PPI group than in controls (12.92 ± 6.27 vs. 8.10 ± 4.21 per 100 epithelial cells, p