Inhibition of gastric mucin synthesis by Helicobacter pylori.
OBJECTIVE
Mucins are high-molecular-weight glycoproteins that protect the gastric epithelium. Previous data suggested that gastric surface-type mucin is decreased in Helicobacter pylori-infected patients and restored after eradication of the infection. Our aim was to determine the effect of H. pylori on mucin synthesis in cultured gastric epithelial cells.


METHODS
Mucin synthesis was measured by labeling with [(3)H]glucosamine and size-exclusion chromatography. Expression of MUC5AC and MUC1 mucin protein antigens was quantitated by Western blot analysis.


RESULTS
Mucin synthesis was inhibited more than 80% when KATO III cells were incubated with H. pylori, with no effect on mucin secretion or degradation. Inhibition was rapid (4 hours), partially reversible, dependent on concentration of bacteria, and associated with the insoluble membrane fraction. H. pylori decreased levels of MUC5AC and MUC1 mucins. MUC1 inhibition was half-maximal by 4 hours and partially reversed by 24 hours, but the decrease in MUC5AC was less rapid and not reversible within 24 hours.


CONCLUSIONS
H. pylori inhibits total mucin synthesis in vitro and decreases the expression of MUC5AC and MUC1. A decrease in gastric mucin synthesis in vivo may disrupt the protective surface mucin layer.
Byrd
J C
JC
Gastrointestinal Cancer Research Laboratory, Henry Ford Health Sciences Center, Detroit, Michigan, USA.
Yunker
C K
CK
Xu
Q S
QS
Sternberg
L R
LR
Bresalier
R S
RS
D015153:Blotting, Western; D002458:Cell Fractionation; D004847:Epithelial Cells / Q000378:metabolism / Q000382:microbiology; D005753:Gastric Mucosa / Q000166:cytology / Q000378:metabolism* / Q000382:microbiology*; D016481:Helicobacter Infections / Q000378:metabolism*; D016480:Helicobacter pylori; D006801:Humans; D055271:Mucin 5AC; D018396:Mucin-1 / Q000032:analysis / Q000096:biosynthesis; D009077:Mucins / Q000032:analysis / Q000096:biosynthesis*; D010446:Peptide Fragments / Q000032:analysis / Q000096:biosynthesis; D013274:Stomach Neoplasms; D014407:Tumor Cells, Cultured
C116055:MUC1 tandem repeat peptide; C524678:MUC5AC protein, human; D055271:Mucin 5AC; D018396:Mucin-1; D009077:Mucins; D010446:Peptide Fragments