Expression, localization and systemic concentration of vascular endothelial growth factor (VEGF) and its receptors in patients with ulcerative colitis.

Vascular endothelial grow factor (VEGF) promotes angiogenesis by activating the specific receptors KDR and Flt-1. We investigate the expression of genes encoding VEGF and its receptors KDR and Flt- 1 by RT-QPCR reaction using Quanti Tect SYBR Green RT-PCR in patients with active and inactive ulcerative colitis (UC) and control subjects. The localization and level of VEGF protein and its receptors protein in intestinal tissue were estimated by immunohistochemistry. VEGF concentration in serum and plasma was determined by ELISA. We found a significant increase of VEGF gene expression and increase expression of genes encoding receptor Flt-1 in patients with active UC when compared with controls, but KDR was present in trace amount. VEGF and Flt-1 proteins were colocalized in enterocytes as well as in endothelium and muscularis layer of the intestine. The specific staining reaction for VEGF protein as well as for Flt-1 protein was significantly higher in active UC compared with controls. Serum level of VEGF was significantly higher in active UC patients as compared with inactive UC patients as well as with controls. The plasma VEGF level was found to be significantly higher in active UC patients as compared with controls. The increase of gene expression as well as protein level for VEGF and its receptor in UC - inflamed colon, and VEGF action via Flt-1 receptor may have a functional role in UC. Increased VEGF levels in both serum and plasma in active UC patients may reflect VEGF overexpression in intestinal inflammatory tissue.