Helicobacter pylori outer membrane proteins and gastroduodenal disease

Background and aims: A number of Helicobacter pylori outer membrane
proteins (OMPs) undergo phase variations. This study examined the
relation between OMP phase variations and clinical outcome.Methods:
Expression of H pylori BabA, BabB, SabA, and OipA proteins was
determined by immunoblot. Multiple regression analysis was
performed to determine the relation among OMP expression, clinical
outcome, and mucosal histology.Results:H pylori were cultured from
200 patients (80 with gastritis, 80 with duodenal ulcer (DU), and
40 with gastric cancer). The most reliable results were obtained
using cultures from single colonies of low passage number.
Stability of expression with passage varied with OipA > BabA
> BabB > SabA. OipA positive status was significantly
associated with the presence of DU and gastric cancer, high H
pylori density, and severe neutrophil infiltration. SabA positive
status was associated with gastric cancer, intestinal metaplasia,
and corpus atrophy, and negatively associated with DU and
neutrophil infiltration. The Sydney system underestimated the
prevalence of intestinal metaplasia/atrophy compared with systems
using proximal and distal corpus biopsies. SabA expression
dramatically decreased following exposure of H pylori to pH 5.0 for
two hours.Conclusions: SabA expression frequently switched on or
off, suggesting that SabA expression can rapidly respond to
changing conditions in the stomach or in different regions of the
stomach. SabA positive status was inversely related to the ability
of the stomach to secrete acid, suggesting that its expression may
be regulated by changes in acid secretion and/or in antigens
expressed by the atrophic mucosa.