I L Beales1, J Calam. 1. Department of Gastroenterology, Royal Postgraduate Medical School, Hammersmith Hospital, London, UK.
Abstract
OBJECTIVE: To examine the regulation of granulocyte-macrophage colony-stimulating factor (GM-CSF) production by gastric epithelial cells in Helicobacter pylori infection. DESIGN: The effect of H. pylori infection on gastric GM-CSF production was assessed using short-term culture of antral biopsies. The mechanism of GM-CSF induction was investigated using a gastric epithelial cancer cell line. METHODS: Production of GM-CSF was assessed by enzyme-linked immunosorbent assay. The mechanism of stimulation of GM-CSF production was examined by co-culture of AGS carcinoma cells with H. pylori and specific stimulants and inhibitors. RESULTS: Biopsies from H. pylori-negative patients in the basal state did not produce GM-CSF. However, over 24 h in the presence of the active phorbol ester, phorbol myristate acetate (PMA), significant release of GM-CSF was seen. H. pylori-positive biopsies produced significantly more GM-CSF in both the unstimulated and PMA-stimulated state than H. pylori-negative biopsies. Constitutive release of GM-CSF from cultured human gastric AGS cells could be significantly enhanced by co-culture with live H. pylori or the addition of interleukin-1 beta, tumour necrosis factor alpha and PMA, but not by exposure to forskolin. The protein kinase C inhibitor staurosporine abolished the stimulatory effect of PMA on AGS cells, whereas the protein-tyrosine kinase inhibitor herbimycin A prevented the stimulation of GM-CSF production seen with H. pylori and both cytokines. CONCLUSION: H. pylori enhances GM-CSF production by gastric epithelia. H. pylori appears to stimulate gastric epithelial cells directly to produce GM-CSF and this stimulation involves a tyrosine kinase dependent step. Induction of GM-CSF may play a role in the initiation and perpetuation of gastric inflammation in H. pylori infection.
OBJECTIVE: To examine the regulation of granulocyte-macrophage colony-stimulating factor (GM-CSF) production by gastric epithelial cells in Helicobacter pyloriinfection. DESIGN: The effect of H. pylori infection on gastric GM-CSF production was assessed using short-term culture of antral biopsies. The mechanism of GM-CSF induction was investigated using a gastric epithelial cancer cell line. METHODS: Production of GM-CSF was assessed by enzyme-linked immunosorbent assay. The mechanism of stimulation of GM-CSF production was examined by co-culture of AGS carcinoma cells with H. pylori and specific stimulants and inhibitors. RESULTS: Biopsies from H. pylori-negative patients in the basal state did not produce GM-CSF. However, over 24 h in the presence of the active phorbol ester, phorbol myristate acetate (PMA), significant release of GM-CSF was seen. H. pylori-positive biopsies produced significantly more GM-CSF in both the unstimulated and PMA-stimulated state than H. pylori-negative biopsies. Constitutive release of GM-CSF from cultured human gastric AGS cells could be significantly enhanced by co-culture with live H. pylori or the addition of interleukin-1 beta, tumour necrosis factor alpha and PMA, but not by exposure to forskolin. The protein kinase C inhibitor staurosporine abolished the stimulatory effect of PMA on AGS cells, whereas the protein-tyrosine kinase inhibitor herbimycin A prevented the stimulation of GM-CSF production seen with H. pylori and both cytokines. CONCLUSION:H. pylori enhances GM-CSF production by gastric epithelia. H. pylori appears to stimulate gastric epithelial cells directly to produce GM-CSF and this stimulation involves a tyrosine kinase dependent step. Induction of GM-CSF may play a role in the initiation and perpetuation of gastric inflammation in H. pylori infection.