Background/aims: Gastrointestinal epithelia contain a powerful protease inhibitor called pancreatic secretory trypsin inhibitor (PSTI). Gastric mucus obtained from patients with atrophic gastritis or gastric ulceration shows changes suggestive of excessive proteolytic digestion. Therefore, the aim of this study was to examine whether mucosal PSTI levels are affected by gastritis and/or ulceration.
Methods: Mucosal PSTI levels were measured in 12 patients with normal gastric histology and 26 patients with gastritis and/or gastric ulceration.
Results: In control subjects, mean gastric PSTI concentrations were 990 ng/mg protein (95% confidence interval, 819-1195) in the antrum and 445 ng/mg protein (95% confidence interval, 395-502) in the body. Immunostaining for PSTI was strongly positive in the pyloric glands of the antrum and in the foveolar/surface and mucus neck cells of the gastric body. Tissue levels of PSTI were reduced by 40% in biopsy specimens showing superficial gastritis (P = 0.035) and by 75% in biopsy specimens showing atrophic gastritis and/or gastric ulceration (P < 0.001). Immunostaining was also reduced in specimens showing atrophic gastritis.
Conclusions: The decrease in tissue PSTI levels associated with gastric atrophy probably represents a permanent reduction in one of the mucosal defense mechanisms. This may lead to the maintenance and even expansion of the gastritic process with time.