Expression patterns of angiopoietin-1, -2, and tie-2 receptor in ulcerative colitis support involvement of the angiopoietin/tie pathway in the progression of ulcerative colitis.

The active stage of ulcerative colitis (UC) involves transmigration of polymorphonuclear (PMN) cells to colonic epithelia. The angiopoietin (Ang) pathway plays a role as the regulator of PMN transmigration. To clarify the role of the Ang/Tie pathway in the activation of UC, especially in cypt abscess formation, 67 tissue samples were obtained from patients with UC and ten controls without UC for immunohistochemical analysis for the expression of Ang-1, -2, or Tie-2. The epithelia of crypt abscess was strongly positive for Ang-1 and -2 for all 57 samples derived from patients with active UC, though the colorectal epithelium without crypt abscess showed minimal expression of Ang-1, -2, and Tie-2. Numerous transepithelial migrating PMN cells in crypt abscesses also expressed Tie-2. The specimens of UC patients in remission showed significantly less immunoreactivity for Ang-1, -2, or Tie-2. These findings suggest that the Ang/Tie pathway may play a role in the progression of UC.