Helicobacter pylori infection and neopterin

Abstract

In order to find out whether chronic immune stimulation is associated with Helicobacter pylori infection we studied 425 healthy individuals (aged 57.6 ± 9.22 years, s.d.) who were performing a health check up without having any specific health problems. Blood was drawn for H. pylori antibody testing, determination of routine laboratory parameters, differential blood count and measuring neopterin concentrations. In addition, in individuals seropositive for H. pylori, measurement of 13CO2 exhalation after administration of 75 mg 13C-Urea was performed to test for the presence of these microorganisms in the gut. One hundred and ninety subjects were H. pylori seropositive (antibody titer > 4) and they had higher serum neopterin concentrations (serum neopterin: 6.38 nM ± 3.3 S.D.) compared to seronegative subjects (serum neopterin: 5.74 ± 2.7 nM, p =0.027, Student's t-test). Among the H. pylori seropositive individuals no such difference existed between breath test positive (serum neopterin: 6.1 ± 3.1 nM) and negative ones (serum neopterin: 6.1 ± 2.0 nM; p = n. s.). Increased production of neopterin is indicative for an activated cellular immune response. Antibody seropositive patients present with higher neopterin levels than seronegatives even when H. pylori seemed to be no longer present in the gut. Surprisingly neopterin concentrations were not related to the presence/absence of bacteria in the gut. Higher neopterin concentrations in H. pylori seropositive individuals would be in good agreement with the view of H. pylori infection as a risk factor for developing atherosclerosis, since in earlier studies carotid stenosis was found to be associated with higher neopterin concentrations. In that study as in ours, the great majority of neopterin concentrations found were well within the normal range of healthy controls. Our data point to a role of H. pylori to induce a long-lasting albeit moderate deterioration of the cellular immune system, which may contribute to increase the risk of atherosclerosis.