Changes of nitric oxide and growth factors during gastric ulcer healing

We measured the concentrations of vascular endothelial growth factor (VEGF), nitric oxide and endothelin-1 (ET-1) in the gastric mucosa and examined the relationships between these factors. VEGF, nitric oxide and ET participate in angiogenesis and vascular remodeling, important elements of gastric ulcer healing. We studied cases of gastric ulcer as confirmed by endoscopic examination. All 61 cases in the angulus were positive for Helicobacter pylori (Hp). Fifteen cases were active stage (GA), 23 were healing stage (GH), and 23 were scarring stage (GS). As control, 17 cases of Hp-positive gastritis (gast+) and 14 cases of Hp-negative gastritis (gast-) were studied. Biopsy samples taken from the angulus during endoscopic examination were frozen and sliced into thin sections. ET was measured by enzyme immunoassay, VEGF was measured by enzyme-linked immunosorbent assay (ELISA) and nitric oxide was measured in terms of metabolite oxides of nitrogen (NOx) as described by Griess. ET, VEGF and inducible nitric oxide synthase (iNOS) were immunostained. The GA group had the highest concentration of NOx, suggesting that nitric oxide participates in the early stage of mucosal repair. In the GH group, all three factors showed high concentrations, suggesting that all may be involved in increased production. In the GS group, all three factors were significantly lower than in the GA and GH groups. Immunohistochemical studies showed that the distribution of ET- and iNOS-positive cells differed according to the ulcer stage. In particular, ET- and iNOS-positive cells in the vascular wall were primarily endothelial cells during GA and GH and vascular smooth muscle cells (VSMCs) during GS. These findings suggest that endothelial cells produce increased amounts of ET, nitric oxide and VEGF early in ulcer healing, a period of active endothelial cell repair and angiogenesis. During the scarring stage, vascular remodeling may result from the effects of ET and nitric oxide in regulating the proliferation of VSMCs. Our results suggest that VEGF nitric oxide and ET participate in angiogenesis, vascular remodeling and mucosal regeneration during ulcer healing.