Mucosal secretion and expression of basic fibroblast growth factor in patients with collagenous colitis

Collagenous colitis (CC), a condition of unknown ethiology and pathophysiology, is characterized by watery diarrhea and increased amounts of collagen in the colonic mucosa. Basic fibroblast growth factor (bFGF) is a potent multifunctional growth factor that stimulates proliferation and differentiation of fibroblasts that was recently detected in high intraluminal concentrations in patients with ulcerative colitis. In this study we examined the secretion and expression of bFGF in the colorectal mucosa of patients with CC.

Ten CC patients and 10 control patients underwent colonoscope-based segmental perfusion of the descending colon and rectum. The concentrations of bFGF in perfusate and serum were determined by immunochemical methods, and the expression of bFGF was analyzed immunohistochemically in biopsy samples from colonic mucosa.

The median concentrations of bFGF in perfusates from the descending colon and rectum were increased 4-fold in CC patients compared with control patients. The median concentration of bFGF in serum was not significantly different in patients and controls. Immunohistochemical staining of bFGF was located in the colorectal epithelial cells and in exsudate on the luminal side of these cells. In the lamina propria, inflammatory cells and fibroblasts contained bFGF. There were no differences in the intensity of bFGF staining in surface epithelium or lamina propria between patients and controls.

Local investigation of the colorectal mucosa seems to be crucial when studying the pathophysiology of CC. Increased colorectal mucosal secretion of bFGF in patients with CC may promote differentiation of fibroblasts and thereby lead to increased subepithelial collagen deposition.