Secretory leukocyte protease inhibitor expression in various types of gastritis: a specific role of Helicobacter pylori infection

Abstract

Secretory leukocyte protease inhibitor (SLPI) represents a multifunctional protein of the gastrointestinal mucosa exerting antimicrobial and anti-inflammatory effects. SLPI expression is generally induced during inflammation; however, Helicobacter pylori-mediated gastritis is associated with significantly decreased antral SLPI levels. The aim of the study was to investigate whether SLPI downregulation of gastric mucosa represents a specific phenomenon of H. pylori infection or is generally linked to gastric inflammation. SLPI expression was retrospectively analysed by immunohistochemistry in 85 paraffin-embedded samples: H. pylori-induced (n=13), non-steroidal anti-inflammatory drug (NSAID)-enhanced (n=18), autoimmune (n=11), lymphocytic gastritis (n=26) and H. pylori-negative controls (n=17). The intensity of the staining was semiquantitatively analysed using an immunoreactivity score. Statistical analysis of differences was performed using an analysis of variance test. In comparison with the control group, the SLPI expression of antral mucosa in H. pylori-mediated and lymphocytic gastritis was significantly lower (P<0.001), whereas epithelial SLPI expression was not affected in NSAID-enhanced and autoimmune gastritis either in the antrum or corpus, respectively. Both the H. pylori-mediated and lymphocytic gastritis revealed a significantly lower expression of SLPI in infiltrating immune cells (P<0.01), whereas immune cells infiltrating the corpus in autoimmune gastritis showed higher SLPI levels than the immune cells of other groups (P<0.03). The local downregulation of SLPI in antral mucosa is specifically linked to H. pylori infection and is not a general phenomenon of gastric inflammation.