Masamitsu Nakazato

Elevated Concentrations of |[alpha]|-Defensins in Gastric Juice of Patients with Helicobacter pylori Infection

OBJECTIVE:Defensins (α- and β-defensins) are endogenous antimicrobial peptides. Little is known about α-defensins during Helicobacter pylori infection.METHODS:The concentrations of human neutrophil peptides (HNP-1, -2, and -3), the major components of neutrophils-derived α-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 (/mm2) 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.

Gastro-Entero-Pancreatic Actions of Ghrelin

Ghrelin is primarily produced in the stomach and is known to be involved in feeding behavior, gastric function, and cardiovascular function, as well as growth hormone (GH) secretion. Ghrelin cells are believed to correspond morphologically to X/A-like cells whose products and functions have not yet been clarified. Identification of ghrelin cells in the stomach may contribute to the characterization of X/A-like cell function. Ghrelin is also present in the pancreatic islets and regulates insulin release, suggesting that ghrelin may play an important role in energy homeostasis. It is one of the major gut hormones and circulates through the bloodstream; however, ghrelin is thought to convey signals regulating GH release or feeding behavior and is transported to the brain via the vagal afferent system.