Increased lysozyme expression in gastric biopsies with intestinal metaplasia and pseudopyloric metaplasia.

Lysozyme is an innate enzyme with potent non-immunological antibacterial properties in the upper intestinal tract. Lysozyme expression (ly-ex) was investigated in 80 consecutive sets of gastric biopsies having normal gastric mucosa (n=20), chronic gastritis (n=20), gastric intestinal metaplasia (IM, n=20), and pseudopyloric metaplasia (PpM, n=20). In biopsies with normal mucosa and with chronic gastritis, the foveolar epithelium and the mucus neck cells of the fundic mucosa as well as the antropyloric glands had moderate (++) to marked (+++) ly-ex whereas the fundic glands proper did not express lysozyme. In IM the goblet and the Paneth cells showed marked (+++) ly-ex. PpM, developing in patients with autoimmune (corpus) gastritis, had moderate ly-ex (++), thus contrasting with the negative ly-ex in the normal or inflamed fundic mucosa. The Helicobacter pylori did not proliferate in areas with IM or with PpM. The lysozyme production in IM and in PpM might be upregulated to eradicate ingested, proliferating bacteria in acid-deficient stomachs.