RÉSUMÉ
Objective To investigate the relationship between the level of serum iron-cofactored superoxide dismutase (SodB) antibody encoded by Helicobacter pylori (H.pylori) genome in infected populations of H.pylori and the occurrence of gastric cancer.Methods Serum samples from 114 cases and 104 control were collected.Indirect ELISA was used to detect serum SodB antibody level in case group and control group.The relationship between serum SodB antibody level and GC risk was analyzed by conditional logistic regression.The value of SodB in serological screening of gastric cancer was analyzed and evaluated by the receiver operating characteristic (ROC) curve.Results The level of serum SodB antibody was correlated with the occurrence of gastric cancer in subjects with OR=2.287 (95％CI:1.191～4.391)(P＜0.05).The optimal cutoff value of SodB for screening gastric cancer was determined by using receiver operating characteristic (ROC) curve,and it was 0.028 0.The area under the ROC curve for subjects was 0.575 (95 ％ CI:0.501 ～ 0.649).Conclusion The level of serum H.pylori SodB antibody was associated with the occurrence of gastric cancer.SodB alone was not effective in screening gastric cancer.It might be used in combination with other biomarkers of gastric cancer to improve further screening of gastric cancer.
RÉSUMÉ
Helicobacter pylori, a causative agent of gastroduodenal diseases, is a Gram-negative microaerophilic bacterium. Although H. pylori locates in the microaerophilic mucous layer, the bacteria would come into contact harmful reactive oxygen species generated by host immune system. It has been reported that H. pylori harbors various defense mechanisms which can protect bacterial cells from oxygen exposure. The change of the gene expression profile of sodB-negative isogenic mutant of H. pylori 26695 was analyzed by high resolution 2-DE followed by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and tandem MS and microarray analysis. Eighteen genes and 41 genes were upregulated and downregulated respectively, either transcriptionally or translationally. Expression levels of three genes including trxB, yxjE and ribE that were changed both on a mRNA level and on a protein level were confirmed by RT-PCR analysis. However, change of expression levels of other major antioxidants such as KatA, AhpC and NapA were not detected, which means Sod is regulated by different way from that of KatA and AhpC. Mutant study of other antioxidant proteins may give us better understanding for the regulation of stress response in H. pylori.