Vascular endothelial growth factor (VEGF)--a possible mediator of inflammation and mucosal permeability in patients with collagenous colitis.

Patients with collagenous colitis have watery diarrhea and histopathologically thickened collagen layer with discrete signs of mucosal inflammation. Vascular endothelial growth factor (VEGF) is a potent angiogenic, mitogenic, permeability, and fibrosis enhancing peptide and it was studied by segmental perfusion and immunohistochemistry in patients and controls. The concentrations of VEGF were significantly increased in perfusates from both the descending colon and the rectum in patients compared to controls but this difference was not found in serum. Immunohistochemical staining showed expression of VEGF within colon epithelial cells, inflammatory cells, and fibroblasts in the lamina propria. The intensity of staining in the surface epithelium was not different between patients and controls but in the lamina propria the intensity was significantly higher among controls. Patients with collagenous colitis have increased colorectal mucosal secretion of VEGF, which may lead to albumin leakage and promote fibrosis with deposition of collagen.