Chronic infections
negatively influence vaccine efficacies. Helicobacter pylori induced protection against esophageal and cardial
pathologies, childhood asthma, allergies and inflammatory bowel disease strongly
implicates that chronic H. pylori
infection influences the immune system of the host. We hypothesise that chronic H. pylori exposure not only has a
beneficial effect on the host by reducing allergic immune responses but also
impacts on the development of immune responses to vaccines. Our data demonstrate
a systemic immune suppression induced by H.
pylori based on decreased T cell and antibody responses towards vaccine
antigens in bacteria bearing mice. Immune suppression induced by H. pylori is likely mediated through dendritic
cells as dendritic cells isolated from H.
pylori infected hosts exhibit a decreased proinflammatory potential compared
to their control counterparts. We had the unique opportunity to translate our
findings from the mouse model into to human healthy volunteers. Exposure to H. pylori had a slight but significant
impact on pre-existing sera titres to common vaccines. Interestingly we could
identify inter-strains differences in their potency to influence the vaccine
response in our human study warranting further investigation into the
underlying mechanisms how H. pylori
infection modulates the systemic immune system of its host.