Reactive nitrogen species mediate DNA damage in Helicobacter pylori-infected gastric mucosa.
BACKGROUND
Reactive oxygen species (ROS) and reactive nitrogen species (RNS) can play an important role in cellular injury and carcinogenesis of gastric epithelial cells infected with Helicobacter pylori. 8-OH-deoxy guanosine (8-OHdG) and 8-nitroguanine (8-NG) are markers for ROS- and RNS-mediated DNA oxidation, respectively. In this study, RNS-mediated DNA damage in gastric mucosa was observed directly using a newly developed antibody to 8-NG to clarify how H. pylori infection causes nitrative DNA damage to gastric epithelial cells.


METHODS
Immunohistochemistry with anti-8-OHdG and anti-8-NG antibodies was performed on gastric tissue samples from 45 patients (25 men and 20 women) with H. pylori-positive gastritis and 19 patients (11 men and 8 women) exhibiting successful H. pylori eradication. Histologic factors for gastric mucosal inflammation were graded according to the guidelines of the Updated Sydney system.


RESULTS
In corpus mucosa, 8-OHdG and 8-NG production were significantly associated with the degree of glandular atrophy, infiltration of chronic inflammatory cells and intestinal metaplasia in the glandular epithelial cells. Successful H. pylori eradication resulted in a significant reduction of chronic inflammatory cell infiltration and neutrophilic activity. Mean 8-OHdG production was lower after H. pylori eradication in both corpus and antral mucosa (p = .022 and .049, respectively). However, the reduction in 8-NG exhibited was more pronounced than the reduction of 8-OhdG (p = .004 and .007, respectively).


CONCLUSIONS
Helicobacter pylori infection can induce inflammatory cells infiltration, which evokes DNA damage of gastric epithelial cells through ROS and RNS production. 8-NG might be a more sensitive biomarker than 8-OHdG for H. pylori-induced DNA damage in gastric mucosa.
Katsurahara
Masaki
M
Department of Gastroenterology and Hepatology, Division of Clinical Medicine and Biochemical Sciences, Mie University Graduate School of Medicine, Mie, Japan.
Kobayashi
Yoshinao
Y
Iwasa
Motoh
M
Ma
Ning
N
Inoue
Hiroyuki
H
Fujita
Naoki
N
Tanaka
Kyosuke
K
Horiki
Noriyuki
N
Gabazza
Esteban C
EC
Takei
Yoshiyuki
Y
D000328:Adult; D000368:Aged; D004249:DNA Damage; D005260:Female; D005753:Gastric Mucosa / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology; D006147:Guanine / Q000031:analogs & derivatives / Q000378:metabolism; D016481:Helicobacter Infections / Q000235:genetics* / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology; D016480:Helicobacter pylori / Q000276:immunology / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D026361:Reactive Nitrogen Species / Q000378:metabolism*; D055815:Young Adult
C095838:8-nitroguanine; D026361:Reactive Nitrogen Species; D006147:Guanine