Elevated concentrations of alpha-defensins in gastric juice of patients with Helicobacter pylori infection

OBJECTIVE: Defensins (alpha- and beta-defensins) are endogenous antimicrobial peptides. Little is known about alpha-defensins during Helicobacter pylori infection. METHODS: The concentrations of human neutrophil peptides (HNP-1, -2, and -3), the major components of neutrophils-derived alpha-defensins, were measured by radioimmunoassay (RIA) in plasma and gastric juice of 61 H. pylori-infected and 33 uninfected subjects, and before and after anti-H. pylori treatment in 12 patients with H. pylori-associated gastritis. Interleukin (IL)-8 concentrations in gastric juice were measured by enzyme-linked immunosorbent assay. Histological grades of gastritis and neutrophil counts (/mm(2)) infiltrating in the gastric mucosa were determined using two biopsy specimens taken from the antrum and corpus. Immunohistochemistry and reverse-phase high performance liquid chromatography (RP-HPLC) were used to identify HNPs 1-3. RESULTS: HNP 1-3 concentrations in gastric juice were significantly higher in H. pylori-positive than in H. pylori-negative patients and significantly decreased after cure. HNP 1-3 concentrations in gastric juice correlated with IL-8 levels and neutrophil densities in the gastric mucosa and were associated with histological degree of gastritis, especially the grades of activity. Intense immunoreactivity for anti-HNPs 1-3 antiserum was noted in infiltrating neutrophils in H. pylori-infected mucosa. In RP-HPLC analysis, all of the HNP 1-3 molecules were identified as their mature forms. Plasma HNP 1-3 concentrations were similar in H. pylori-infected and non-infected groups and showed no correlations with other parameters. CONCLUSIONS: We demonstrated significantly elevated levels of HNPs 1-3 in gastric juice during H. pylori infection. The elevation of HNPs is presumably secondary to H.pylori-associated gastric inflammation involving neutrophil infiltration.