Water extract of Helicobacter pylori stimulates interleukin-8 secretion by a human gastric epithelial cell line (JR-St) through protein tyrosine phosphorylation.
BACKGROUND
Infection by Helicobacter pylori induces cytokine production in gastric mucosal cells. Production of interleukin-8 (IL-8) is known to be markedly increased and is believed to play an important role in gastric mucosal inflammation. The aim of this study was to elucidate the effects of soluble factors of H. pylori on IL-8 production in a gastric epithelial cell line, JR-St.


METHODS
JR-St cells were cocultured with a H. pylori water extract, live H. pylori or culture medium supernatant for 24 h, then the IL-8 secreted into the culture medium was assayed. The effects of three different inhibitors; (i) an inhibitor of protein kinase C (PKC); (ii) an inhibitor of PKC and protein kinase A (PKA); and (iii) an inhibitor of protein tyrosine kinase (PTK) were also compared. Specific induction of IL-8 mRNA was also examined.


RESULTS
Water extract of H. pylori increased IL-8 secretion 7.72-fold, more than the control. The increase was concentration dependent. Live bacteria, supernatant and water extract significantly stimulated IL-8 secretion. Addition of live bacteria increased IL-8 secretion most strongly, while the effect of water extract was small (22% that of live bacteria). Secretion was not inhibited by the PKC inhibitor staurosporine or the inhibitors of PKA and PKC H7. However, secretion was significantly reduced by the PTK inhibitor herbimycin in a dose-dependent manner. Furthermore, 24 h exposure to water extract increased IL-8 mRNA expression, suggesting water extract increased production of IL-8.


CONCLUSIONS
Some soluble factors of H. pylori can stimulate IL-8 production by JR-St cells. Stimulation was not dependent on PKA or PKC but was, at least partially, dependent on protein tyrosine phosphorylation. This suggests that soluble factors of H. pylori can play an important role in mediating the inflammatory response of H. pylori gastritis.
Yakabi
K
K
The Third Department of Internal Medicine, Teikyo University School of Medicine, Chiba, Japan. yakabi@med.teikyo-u.ac.jp
Ro
S
S
Okazaki
R
R
Shiojima
J
J
Tsuda
K
K
Mimura
H
H
Tomono
H
H
Nakamura
T
T
D001426:Bacterial Proteins / Q000494:pharmacology*; D002478:Cells, Cultured; D018920:Coculture Techniques; D003470:Culture Media / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology; D016480:Helicobacter pylori / Q000502:physiology*; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics; D010766:Phosphorylation / Q000187:drug effects; D016133:Polymerase Chain Reaction; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D003470:Culture Media; D004791:Enzyme Inhibitors; D016209:Interleukin-8; D012333:RNA, Messenger; D012269:Ribosomal Proteins; C039747:ribosomal protein S14; D011505:Protein-Tyrosine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C