Expression of inducible nitric oxide synthase and nitric oxide-modified proteins in Helicobacter pylori-associated atrophic gastric mucosa.
OBJECTIVE
Induction of inducible nitric oxide synthase (iNOS) may be involved in carcinogenesis of the stomach, because nitric oxide (NO) derived from iNOS can exert DNA damage and post-transcriptional modification of target proteins. In the present study, we investigated the correlation between endoscopic findings and iNOS mRNA expression/NO-modified proteins in the gastric mucosa.


METHODS
Fifty patients were prospectively selected from subjects who underwent upper gastrointestinal chromoendoscopy screening for abdominal complaints. The Helicobacter pylori (H. pylori) status of patients was determined by anti-H. pylori IgG antibody levels. We classified the mucosal area of the fundus as F0, fine small granules; F1, edematous large granules without a sulcus between granules; F2, reduced-size granules with a sulcus between granules; and F3, irregular-sized granules with extended sulcus between granules. Gastritis was graded using the visual analog scale of the Updated Sydney System. The expression of interleukin (IL)-8 and iNOS mRNA was assayed in gastric biopsy specimens by reverse transcription-polymerase chain reaction. NO-modified proteins were analyzed by Western blotting using novel monoclonal antibodies against nitrotyrosine.


RESULTS
A total of 91.7% (11/12) of the F0 group was H. pylori-negative, whereas 94.7% (36/38) of the F1-3 groups was H. pylori-positive. Spearman's analysis showed good correlation between the endoscopic grading and the score of chronic inflammation (r=0.764) and glandular atrophy (r=0.751). The expression of IL-8 mRNA was significantly increased in F1, F2, and F3 cases compared with the F0 group, with no significant differences among them. iNOS mRNA was significantly increased in the F3 group compared with the other groups, with increased nitration of tyrosine residues of proteins.


CONCLUSIONS
The proposed classification by chromoendoscopy is useful for screening patients for atrophic and iNOS-expressing gastric mucosa with NO-modified proteins in H. pylori-associated atrophic gastric mucosa.
Naito
Yuji
Y
Medical Proteomics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto, Japan. ynaito@koto.kpu-m.ac.jp
Takagi
Tomohisa
T
Okada
Hitomi
H
Nukigi
Yayoi
Y
Uchiyama
Kazuhiko
K
Kuroda
Masaaki
M
Handa
Osamu
O
Kokura
Satoshi
S
Yagi
Nobuaki
N
Kato
Yoji
Y
Osawa
Toshihiko
T
Yoshikawa
Toshikazu
T
D000907:Antibodies, Bacterial / Q000097:blood; D001284:Atrophy; D015415:Biomarkers / Q000032:analysis; D005753:Gastric Mucosa / Q000201:enzymology* / Q000382:microbiology / Q000473:pathology; D005757:Gastritis, Atrophic / Q000201:enzymology* / Q000382:microbiology / Q000473:pathology; D005773:Gastroscopy / Q000379:methods; D016481:Helicobacter Infections / Q000201:enzymology / Q000382:microbiology* / Q000473:pathology; D016480:Helicobacter pylori / Q000276:immunology / Q000472:pathogenicity*; D006801:Humans; D016209:Interleukin-8 / Q000032:analysis; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000032:analysis* / Q000235:genetics; D011446:Prospective Studies; D011506:Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D012720:Severity of Illness Index; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000032:analysis
D000907:Antibodies, Bacterial; D015415:Biomarkers; C508606:CXCL8 protein, human; D016209:Interleukin-8; D011506:Proteins; D012333:RNA, Messenger; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; C496319:NOS2 protein, human; D052247:Nitric Oxide Synthase Type II