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World J Gastroenterol. May 21, 2009; 15(19): 2381-2388
Published online May 21, 2009. doi: 10.3748/wjg.15.2381
Detection and evaluation of antibodies against neutrophil-activating protein of Helicobacter pylori in patients with gastric cancer
Min Long, Jun Luo, Yan Li, Fang-Yin Zeng, Ming Li
Min Long, Jun Luo, Department of Medical Microbiology, School of Public Health and Tropical Disease, School of Biotechnology, Southern Medical University, Guangzhou 510515, Guangdong Province, China
Fang-Yin Zeng, Department of Clinical Laboratory, Nanfang Hospital, Southern Medical University, Guangzhou 510515, Guangdong Province, China
Yan Li, Ming Li, School of Biotechnology, Southern Medical University, Guangzhou 510515, Guangdong Province, China
Author contributions: Long M designed the study, analyzed and interpreted the data, and wrote the manuscript; Luo J cloned HP-NAP and detected its antibodies; Li Y cultured Helicobacter pylori and purified HP-NAP; Zeng FY collected the serum samples and supported the technology; Li M contributed to the acquisition funding and supervision.
Correspondence to: Dr. Ming Li, School of Biotechnology, Southern Medical University, Guangzhou 510515, Guangdong Province, China. mingli2006_2006@126.com
Telephone: +86-20-61648550
Fax: +86-20-61648550
Received: December 14, 2008
Revised: April 11, 2009
Accepted: April 18, 2009
Published online: May 21, 2009
Abstract

AIM: To detect and evaluate the antibodies against Helicobacter pylori (H pylori) neutrophil-activating protein (HP-NAP) in patients with gastric cancer and other gastroduodenal diseases.

METHODS: Recombinant HP-NAP was prepared from a prokaryotic expression system in Escherichia coli. Serum positivity and level of HP-NAP-specific antibodies in sera from 43 patients with gastric cancer, 28 with chronic gastritis, 28 with peptic ulcer, and 89 healthy controls were measured by rHP-NAP-based ELISA. rHP-NAP-stimulated production of interleukin-8 (IL-8) and growth-related oncogene (GROα) cytokines in the culture supernatant of SGC7901 gastric epithelial cells was also detected.

RESULTS: The serum positivity and mean absorbance value of HP-NAP-specific antibodies in the gastric cancer group (97.7% and 1.01 ± 0.24) were significantly higher than those in the chronic gastritis group (85.7% and 0.89 ± 0.14, P < 0.005) and healthy control group (27.7% and 0.65 ± 0.18, P < 0.001). The sensitivity and specificity of ELISA for the detection of HP-NAP-specific antibodies were 95.5% and 91.5%, respectively. HP-NAP could slightly up-regulate IL-8 production in gastric epithelial cell lines but had no effect on GROα production.

CONCLUSION: Infection with virulent H pylori strains secreting HP-NAP is associated with severe gastroduodenal diseases, and HP-NAP may play a role in the development of gastric carcinoma. rHP-NAP-based ELISA can be used as a new method to detect H pylori infection. The direct effect of HP-NAP on gastric epithelial cells may be limited, but HP-NAP may contribute to inflammatory response or carcinogenesis by activating neutrophils.

Keywords: Helicobacter pylori; Helicobacter pylori neutrophil-activating protein; Gastric cancer; Peptic ulcer; Chronic gastritis