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Summary Background : Lactobacillus johnsonii (Lj1) had an in vitro and in vivo inhibitory effect on Helicobacter pylori. Fermented milk containing Lj1 (LC1), coadministered with antibiotics had a favourable effect on H. pylori gastritis. Aim : Evaluate the effect of LC1 intake without antibiotics on H. pylori gastritis. Methods : Fifty H. pylori positive healthy volunteers were randomised in a double-blind study to LC1 or placebo. Gastric biopsies from the antrum and corpus were obtained before, and after 3 and 16 weeks of treatment, for histology and quantitative cultures. Results : Severity and activity of antral gastritis was reduced after 16-week LC1 intake (pretreatment and 16-week inflammatory cell score: 6.0 ± 0.8 vs. 5.3 ± 0.1; P = 0.04). H. pylori density decreased in the antrum after LC1 intake (3-week: 4.4 ± 0.6; 16-week: 4.3 ± 0.5 log10 colony forming units (cfu) vs. pretreatment 4.5 ± 0.4 log10 cfu; P = 0.04, respectively). Mucus thickness increased after 16 weeks of LC1 consumption (change of mucus thickness with LC1 and placebo in the antrum: 0.6 ± 1.3 vs. -0.2 ± 1.0, P = 0.01; in the corpus: 0.3 ± 1.1 vs. -0.6 ± 1.5, P = 0.03). Conclusion : LC1 intake had a favourable, albeit weak, effect on H. pylori associated gastritis, particularly in the antrum. Regular ingestion of fermented milk containing L. johnsonii may reduce the risk of developing disorders associated with high degrees of gastric inflammation and mucus depletion.

Urease is an important virulence factor for Helicobacter pylori and is critical for bacterial colonization of the human gastric mucosa. Specific inhibition of urease activity has been proposed as a possible strategy to fight this bacteria which infects billions of individual throughout the world and can lead to severe pathological conditions in a limited number of cases. We have selected peptides which specifically bind and inhibit H. pylori urease from libraries of random peptides displayed on filamentous phage in the context of pIII coat protein. Screening of a highly diverse 25-mer combinatorial library and two newly constructed random 6-mer peptide libraries on solid phase H. pylori urease holoenzyme allowed the identification of two peptides, 24-mer TFLPQPRCSALLRYLSEDGVIVPS and 6-mer YDFYWW that can bind and inhibit the activity of urease purified from H. pylori. These two peptides were chemically synthesized and their inhibition constants (Ki) were found to be 47 microM for the 24-mer and 30 microM for the 6-mer peptide. Both peptides specifically inhibited the activity of H. pylori urease but not that of Bacillus pasteurii.