['Gastrokine-1 is a novel protein that plays an important role in the maintenance of the integrity of the gastric mucosa. However, whether Helicobacter pylori infection and non-steroidal anti-inflammatory drugs, which are known to cause gastric mucosal injuries, affect gastrokine-1 expression in the gastric mucosa is unknown. The aim of the present study was to determine gastric mucosal expression of gastrokine-1 in patients with Helicobacter pylori infection or long-term non-steroidal anti-inflammatory drug administration.', 'A total of 40 patients with functional dyspepsia (20 with Helicobacter pylori-negative chronic gastritis, and 20 with Helicobacter pylori-positive chronic gastritis), and 37 Helicobacter pylori-negative long-term non-steroidal anti-inflammatory drug users (26 with aspirin, 11 with selective cyclooxygenase-2 inhibitors) were selected. In addition, 20 Helicobacter pylori-negative healthy volunteers were recruited as controls. All subjects underwent endoscopies with biopsies taken from the antrum and the sites with lesions. Gastric mucosal changes were detected endoscopically and histologically, and gastrokine-1 protein expression in the antral mucosa was analyzed by immunohistochemistry.', 'Expression of gastrokine-1 protein was decreased in Helicobacter pylori-positive chronic gastritis compared with Helicobacter pylori-negative subjects and the healthy controls. Similarly, gastrokine-1 expression in non-steroidal anti-inflammatory drug users was also decreased, compared with the healthy controls, but there was no significant difference in gastrokine-1 expression between the aspirin group and selective cyclooxygenase-2 inhibitor group. Moreover, gastrokine-1 expression levels tended to be associated with the severity of chronic gastritis.'] Do helicobacter pylori infection and administration of non-steroidal anti-inflammatory drugs down-regulate the expression of gastrokine-1 in gastric mucosa?