Servicio de Información Comunitario sobre Investigación y Desarrollo - CORDIS

In vitro and in vivo antibacterial activity of probiotics against Helicobacter pylori, mechanisms of action, and kinetic analysis

During the course of the project, it has been found that certain Lactobacillus strains inhibit the bacterial pathogen Helicobacter pylori. Probiotics could be used in the treatment and/or prevention of this bacterial infection as an alternative for the triple antibiotic therapy currently used. Recently, there are increasing rates of antibiotic-resistant H. pylori strains. Moreover, the use of antibiotics has several adverse effects.

The antibacterial activity of lactobacilli was demonstrated using in vitro and in vivo methods. In initial experiments, it was shown that (concentrated) cell-free culture supernatants (CFCS) of lactobacilli kill a type strain of H. pylori as well as clinical isolates. Further, cell line culture experiments revealed that pre-treatment of H. pylori with CFCS of certain lactobacilli, such as Lactobacillus johnsonii La1, Lb. casei Shirota, and Lb. amylovorus DCE 471, significantly decrease H. pylori binding to human adenocarcinoma AGS cells. Similarly, CFCS of lactobacilli cause a significant attenuation of Interleukin-8 secretion by H. pylori-infected AGS cells.

Using a mouse model it was revealed that administration of Lb. johnsonii La1 results in a significant delay of both chronic and chronic active gastritis after 6 and 12 weeks. Further, significantly reduced levels of pro-inflammatory cytokines, MIP-2 and Gro-alpha/KC, were detected in the Lb. johnsonii La1-treated H. pylori-infected animals. The potential of using established probiotic strains or new isolates in the combat of H. pylori has to be further invastigated through human intervention studies.

The identification-purification of the anti-H. pylori compound(s) produced by lactobacilli revealed that proteinaceous compounds (possibly bacteriocins) are involved in the antibacterial activity. Bacteriocin production by Lb. johnsonii La1 is growth-associated and the maximal bacteriocin titre is reached at the end of the exponential growth phase. Pure bacteriocin samples could be used in in vivo experiments investigating their possible anti-H. pylori activity.

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