Role of bacterial and genetic factors in gastric cancer in Costa Rica

AIM: To evaluate several risk factors for gastric cancer (GC) in Costa Rican regions with contrasting GC incidence rate (GCIR). METHODS: According to GCIR, 191 Helicobacter pylori (H pylori)-positive patients were classified into groups A (high GCIR, n = 101) and B (low GCIR, n = 90). Human DNA obtained from biopsy specimens was used in the determination of polymorphisms of the genes coding for interleukin (IL)-1β and IL-10 by PCR-RFLP, and IL-1RN by PCR. H pylori DNA extractions obtained from clinical isolates of 83 patients were used for PCR-based genotyping of H pylori cagA, vacA and babA2. Human DNA from gastric biopsies of 52 GC patients was utilized for comparative purposes. RESULTS: Cytokine polymorphisms showed no association with GCIR variability. However, gastric atrophy, intestinal metaplasia and strains with different vacA genotypes in the same stomach (mixed strain infection) were more frequently found in group A than in group B, and cagA and vacA s1b were signif icantly associated with high GCIR (P = 0.026 and 0.041, respectively). IL- 1β+3954_T/C (OR 2.1, 1.0-4.3), IL-1RN*2/L (OR 3.5, 1.7-7.3) and IL-10-592_C/A (OR 3.2, 1.5-6.8) were individually associated with GC, and a combination of these cytokine polymorphisms with H pylori vacA s1b and m1 further increased the risk (OR 7.2, 1.4-36.4). CONCLUSION: Although a proinflammatory cytokine genetic profile showed an increased risk for developing GC, the characteristics of H pylori infection, in particular the status of cagA and vacA genotype distribution seemed to play a major role in GCIR variability in Costa Rica.

Clinical relevance of Helicobacter pylori babA2 and babA2/B in Costa Rica and Japan

AIM:To evaluate the prevalence of Helicobacter pylori(H.pylori ) babA2 ,babB and a recombinant gene between babA2 and babB(babA2/B ),and their role in the development of atrophic gastritis in Costa Rican and Japanese clinical isolates.METHODS:A total of 95 continuous H.pylori-positive Costa Rican(41 males and 54 females;mean age,50.65 years;SD,± 13.04 years) and 95 continuous H.pylori-positive Japanese(50 males and 45 females;mean age,63.43;SD,± 13.21 years) patients underwent upper endoscopy from October 2005 to July 2006.They were enrolled for the polymerase chain reaction(PCR)-based genotyping of the H.pylori babA2 ,babB and babA2/B genes.Statistical analysis was performed using the χ2 test and the Fisher's exact probability test and multivariate analysis was performed by logistic regression adjusting for gender and age.P < 0.05 was regarded as statistically significant.RESULTS:The PCR-based genotyping of 95 Costa Rican and 95 Japanese isolates showed a higher prevalence of babA2 in Japan(96.8%) than in Costa Rica(73.7%),while that of babA2/B was higher in Costa Rica(11.6%) than in Japan(1.1%).In Costa Rican isolates only,babA2 was significantly associated with atrophic gastritis(P = 0.01).CONCLUSION:These results suggest that the status of babA2 and babA2/B shows geographic differences,and that babA2 has clinical relevance in Costa Rica.