Guinea pig gastric mucosal cells produce abundant superoxide anion through an NADPH oxidase-like system.
OBJECTIVE
Superoxide anion (O2-) plays an important role in gastric pathophysiology. The aims of this study were to identify O2--producing activity in gastric mucosal cells and to elucidate its possible roles in inflammatory responses of the cells.


METHODS
The amount of O2- was measured by the reduction of cytochrome c, and O2--producing cells were visualized by nitroblue tetrazolium reaction. Cytosolic components of the phagocyte reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase were detected by immunoblotting and immunocytochemical analyses with antibodies against p47-phox and p67-phox.


RESULTS
Gastric pit cells, but not parietal cells, spontaneously released O2- at 50 nmol . mg protein-1 . h-1. NADPH or guanosine 5'-O-(3-thiotriphosphate) increased the release more than threefold, whereas diphenylene iodonium inhibited it. A reconstituted cell-free system showed that both membrane fraction and neutrophil-related cytosolic components were required for the activity. p47-phox and p67-phox were expressed in the cells. Live Helicobacter pylori organisms and their culture supernatants significantly increased the O2- release. Furthermore, H. pylori lipopolysaccharide could enhance the release more effectively than Escherichia coli lipopolysaccharide. The O2--dependent activation of nuclear factor kappaB occurred in these primed cells.


CONCLUSIONS
Gastric pit cells may actively regulate inflammatory responses of gastric mucosa through a phagocyte NADPH oxidase-like activity.
Teshima
S
S
Department of Nutrition, School of Medicine, University of Tokushima, Tokushima, Japan.
Rokutan
K
K
Nikawa
T
T
Kishi
K
K
D000818:Animals; D002474:Cell-Free System / Q000378:metabolism; D002478:Cells, Cultured; D004926:Escherichia coli; D005753:Gastric Mucosa / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D006168:Guinea Pigs; D016480:Helicobacter pylori / Q000502:physiology; D008070:Lipopolysaccharides / Q000494:pharmacology; D019255:NADPH Oxidases / Q000378:metabolism*; D016328:NF-kappa B / Q000187:drug effects / Q000502:physiology; D010100:Oxygen / Q000378:metabolism; D010750:Phosphoproteins / Q000032:analysis; D013481:Superoxides / Q000378:metabolism*
D008070:Lipopolysaccharides; D016328:NF-kappa B; D010750:Phosphoproteins; C079789:neutrophil cytosol factor 67K; D013481:Superoxides; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D010100:Oxygen