Hypoxia‐inducible factor‐1 alpha and vascular endothelial growth factor expression in ischaemic colitis and ulcerative colitis

Abstract

SummaryBackgroundHypoxia‐inducible factor‐1 alpha (HIF‐1 alpha) is a transcriptional factor induced by ischaemic crisis in many tissues. Vascular endothelial growth factor (VEGF) is an important growth factor that plays a major role in angiogenesis.AimWe examined the aetiology and pathophysiology of human ischaemic colitis and ulcerative colitis from the viewpoint of the expression of these two ischaemic factors.MethodsThirty‐two patients with ischaemic colitis, 16 with ulcerative colitis and 25 normal controls underwent colonoscopy. Biopsy samples were taken from a colitis lesion and a normal region in the same patient. In the normal controls, four biopsy samples were obtained from each subject. Biopsy samples were subjected to real‐time polymerase chain reaction.ResultsHypoxia‐inducible factor and VEGF were overexpressed in ischaemic colitis lesions and quickly decreased to normal levels in the healing phase. In contrast, HIF but not VEGF was overexpressed in active ulcerative colitis lesions. In the remission phase of ulcerative colitis, VEGF decreased to low levels, although HIF was continuously overexpressed.ConclusionsOverexpression of HIF and VEGF contribute to the tolerance of ischaemia in patients with active ischaemic colitis. The inconsistency in their expression might be associated with the chronic intestinal damage characteristic of ulcerative colitis.