Abstract

Previously, we performed a detailed in vitro characterization of the probiotic properties and the anti-Helicobacter pylori activity of Lactobacillus fermentum UCO-979C isolated from human stomach. We demonstrated that the UCO-979C strain strongly inhibited the adhesion, growth and urease activity of H. pylori in gastric adenocarcinoma human (AGS) cells. Moreover, L. fermentum UCO-979C was able to beneficially modulate the cytokine response of AGS cells and macrophages after H. pylori infection. However, no in vivo studies had been performed with this strain in order to confirm effects on immune response related with H. pylori infection. Therefore, the aim of this work was to evaluate whether L. fermentum UCO-979C improves protection against H. pylori infection in mice and modulates the innate immune response. For this purpose, adult Swiss mice were treated with 108 cells/mouse/day of L. fermentum UCO-979C in the drinking water during two consecutive days. Lactobacilli-treated and untreated control mice were then challenged with H. pylori SS1 (100μl of an inoculum containing 108 cells/ml by oral route). The resistance to the infection as well as the innate immune response were studied at day 2 post-infection. H. pylori was recovered from the gastric tissue of all the infected animals. However, UCO-979C-treated mice showed significantly lower bacterial cell counts (p<0.05) as well as urease activity (p<0.01) in gastric tissue when compared to controls. Moreover, histological studies showed that the potential immunobiotic strain significantly reduced gastric tissue damage and inflammatory cells infiltration. H. pylori infection increased the levels of TNF-α, IL-8, MCP-1, IFN-γ and IL-10 in the gastric tissue as well as in serum in all the infected mice. Of note, lactobacilli-treated mice had significantly lower levels of gastric and serum TNF-α, IL-8, and MCP-1, and higher values of IFN-γ and IL-10 than control mice. Our studies confirmed in vivo the anti-H. pylori activity of L. fermentum UCO-979C and its capacity to beneficially regulate the production of cytokines, ameliorating gastric inflammation.