Helicobacter pylori vac A genotype is a predominant determinant of immune response to Helicobacter pylori CagA

摘要

AIM To evaluate the frequency of Helicobacter pylori(H. pylori) Cag A antibodies in H. pylori infected subjects and to identify potential histopathological and bacterial factors related to H. pylori Cag A-immune response.METHODS Systematic data to H. pylori isolates, blood samples, gastric biopsies for histological and molecular analyses were available from 99 prospectively recruited subjects. Serological profile(anti-H. pylori, anti-Cag A) was correlated with H. pylori isolates(cag A, EPIYA, vac A s/m genotype), histology(Sydney classification) and mucosal interleukin-8(IL-8) m RNA and protein expression. Selected H. pylori strains were assessed for H. pylori Cag A protein expression and IL-8 induction in co-cultivation model with AGS cells.RESULTS Thirty point three percent of microbiologically confirmed H. pylori infected patients were seropositive for Cag A. Majority of H. pylori isolates were cag A gene positive(93.9%) with following vac A polymorphisms: 42.4% vac A s1m1, 23.2% s1m2 and 34.3% s2m2. Anti-Cag AIg G seropositivity was strongly associated with atrophic gastritis, increased mucosal inflammation according to the Sydney score, IL-8 and cag A m RNA expression. V a c A s a n d m p o l y m o r p h i s m s w e r e t h e m a j o r determinants for positive(vac A s1m1) or negative(vac A s2m2) anti-Cag A serological immune response, which also correlated with the in vitro inflammatory potential in AGS cells. In vitro co-cultivation of representative H. pylori strains with AGS cells confirmed functional Cag A translocation, which showed only partial correlation with Cag A seropositivity in patients, supporting vac A as major co-determinant of the immune response.CONCLUSION Serological immune response to H. pylori cag A + strain in H. pylori infected patients is strongly associated with vac A polymorphism, suggesting the crucial role of bacterial factors in immune and clinical phenotype of the infection.