GASTROENTEROLOGY 1995;108:65-74 Expression of Interleukin 8 and CD54 by Human Gastric Epithelium After Helicobacter pylori Infection In Vitro SHEILA E. CROWE,* LUIS ALVAREZ,* MARLENE DYTOC,* RICHARD H. HUNT, § MILAN MULLER, ~ PHILIP SHERMAN, t JANAK PATEL, II YIDE JIN, H and PETER B. ERNST II Departments of *Medicine and ilpediatrics, University of Texas Medical Branch, Galveston, Texas; *Division of Gastroenterology, The Hospital for Sick Children, Toronto, Ontario, Canada; and §Department of Medicine, McMaster University, Hamilton, Ontario, Canada Background~Aims: Helicobacter pylori is associated with neutrophil infiltrates, although the mechanism of their recruitment is only partially defined. The aim of the study was to determine if Kato III, a human gastric epithelial cell line, expressed cytokines and the inter- cellular adhesion molecule 1 (ICAM-1), which could contribute to the initiation of inflammation during infec- tion with H. pylori. Methods: Kato III cells were stimu- lated with H. pylori and were examined for evidence of infection, cytokine production, and the expression of ICAM-I. Results: The expression of interleukin 8 mes- senger RNA and immunoreactive protein by Kato III cells was significantly increased over constitutive lev- els within 3 hours of infection with H. pylori. Infected Kato III supernatants activated neutrophils as evi- denced by increased CD11b/CD18 and decreased L- selectin that could be blocked by anti-interleukin 8. In contrast, Campylobacterj'ejuni, lipopolysaccharide, killed H. pylori, and supernatants from cultures of H. pylori did not increase interleukin 8. Interleukins 2 and 6; interferons alfa, beta, and gamma; and tumor necro- sis factor were not produced by resting or H. pylori- stimulated Kato III cells. In addition to producing in- terleukin 8, Kato III constitutively expressed surface ICAM-1, which acts as an intercellular adhesion mole- cule for neutrophils. Conclusions: Our results indicate that H. pylori stimulates the gastric epithelium to initi- ate inflammation and neutrophil recruitment and activa- tion. H elicobacter pylori is the most common cause of type B chronic active gastritis, and infection is also asso- ciated with peptic ulcer disease and gastric cancer. 1'2 Despite the high prevalence of this infection worldwide, the mechanisms of pathogenesis are not well established (reviewed by Ernst and Pecquet3). H. pylori is a gram- negative flagellated bacterium that has a niche restricted to the human gastric mucosa. Generally, H. pylori are viewed as noninvasive pathogens that intimately adhere to the gastric epithelium. 4'5 Infection is characterized by a pleiomorphic inflammatory cell infiltrate of the epithe- lium and underlying lamina propria. Activation of these leukocyte populations is suggested by the local produc- tion of antibodies 6-8 and cytokines, including interleu- kins (ILs) 6 and 8 and tumor necrosis factor (TNF). 9'1° However, because H. pylori does not typically invade the mucosa, it is not clear how the infection initiates this inflammatory response. Earlier experiments suggest that H. pylori can activate inflammatory responses from the lumen by releasing fac- tors that induce neutrophil recruitment and activation. 1.-13 A recent report has shown that gastric epithelial cell lines produce the leukocyte chemoattractant and activating cytokine IL-8 in response to interferon gamma and TNF- (z. I4 Because these cytokines are increased in response to H. pylori stimulation in vivo 9 or in vitro, t5 inflammation induced by bacterial infection could stimulate the gastric epithelium to participate actively in the inflammatory process. This concept is supported by observation that the gastric epithelium expresses increased levels of lacto- ferrin, lysozyme, polymeric immunoglobulin receptor, and major histocompatibility class II molecules during inflammation. *6,*vMoreover, it is known that certain bac- terial and viral infections induce cytokines in epithelial cells of the urinary, 18 intestinal, 19'2° and respiratory ori- gin. 21 In this study, we show that gastric epithelial cells have the ability to initiate changes associated with acute inflammation through the generation of biologically ac- tive IL-8 after infection with H. pylori. Furthermore, we show that the gastric epithelium expresses the neutrophil adhesion molecule CD54 or intracellular adhesion mole- cule 1 (ICAM-1). These data support the theory that the Abbreviations used in this paper: dThd, thymidine; ELISA, enzyme- linked immunosorbent assay; ICAM-1, intracellular adhesion mole- cule 1; IL, interleukin; rt-PCR, reverse-transcription polymerase chain reaction; TNF, tumor necrosis factor. © 1995 by the American Gastroenterological Association 0016-5085/95/$3.00