Galectin-3 expression in pouchitis in patients with ulcerative colitis who underwent ileal pouch-anal anastomosis (IPAA)

Galectin-3, an endogenous pleiotropic beta-galactoside-binding protein, which is expressed by various malignant and normal cells, regulates many biological and pathological processes, including inflammation. In the present study, we tested a possible correlation between the severity of pouchitis in patients with ulcerative colitis who underwent ileal pouch-anal anastomosis (IPAA) and the presence of galectin-3⁺ macrophages in pouch mucosa. Paraffin-embedded pouch biopsies from patients with normal pouch function or chronic and recurrent acute pouchitis were immunohistostained with galectin-3, CD68, and smooth muscle actin (SMA) antibodies. Microscopic examination was performed in a blinded fashion. There was a significant decrease in the staining index of galectin-3 in the subepithelial macrophages in patients with chronic pouchitis (0.53, P=0.001; n=12) or recurrent acute pouchitis (0.43, P=0.008; n=10) when compared to patients with no clinical manifestations of pouchitis (0.63, n=12). No significant differences were noted in the lamina propria of small intestine biopsies from the same patients (from 0.63 to 0.68, P=0.24). Galectin-3 staining was restricted to CD68⁺ macrophages and not present in myofibroblasts. Clinical manifestation of pouchitis is inversely correlated with galectin-3 expression in the pouches' subepithelial lamina propria macrophages.