Persistent increase in myofibroblasts in Helicobacter heilmannii-infected mice but not in Helicobacter pylori-infected Mongolian gerbils:: colocalization of COX-2 and bFGF immunoreactivity

Background:The clinical significance of Helicobacter heilmannii infection remains uncertain, owing to the lack of a specific detection method. Recently, we reported a marked increase in myofibroblasts in the early stage of Helicobacter pylori infection in Monglian gerbils. Aim: The present study was designed to clarify changes in myofibroblasts, and in the immunoeactivities of basic fibroblast growth factor, cyclooxygenase-2 and inducible nitric oxide synthase after H. pylori infection in Monglian gerbils and H. heilmannii infection in mice. Methods: After oral inoculation, changes in the location of bacteria and the immunoreactivity of myofibroblasts, basic fibroblast growth factor, cyclooxygenase-2 and inducible nitric oxide synthase were stained with the indirect immunofluorescent method and observed by confocal laser microscopy. Results: In H. heilmannii -infected mice, the increases in myofibroblasts and in immunoreactivities of these three markers were sustained 12 months after infection. In H. pylori -infected Monglian gerbils, however, these increases were significant at 3 months but had returned to control levels at 12 months. Conclusions: Two types of Helicobacter infection showed different patterns of myofibroblast proliferation, coinciding with the extent of inflammation. These findings suggest that this difference may be related to the consequences of the infection.