Modulatory Effect of Beneficial Enterococci and Their Enterocins on the Blood Phagocytes in Murine Experimental Trichinellosis.

Bacteriocins (enterocins) represent a new therapeutic strategy in various intestinal and non-intestinal infections. In antiparasitic defence, an oxidative inflammation of phagocytes is effective in destroying new-born Trichinella spiralis larvae. The strains Enterococcus faecium CCM8558 and E. durans ED26E/7 and their enterocins, enterocin M and a durancin-like enterocin, respectively, were administered daily, and mice were then infected with T. spiralis larvae on the seventh day of treatment. Phagotest and Bursttest kits were used to detect the phagocytosis and respiratory burst in blood leukocytes. T. spiralis infection inhibited phagocytosis from day 11 post-infection (dpi) during the migration of new-born larvae into the muscles. E. faecium CCM8558, E. durans ED26E/7, and the durancin-like enterocin increased phagocytic activity from day 11 dpi. Both strains and their enterocins (enterocin M and durancin-like) stimulated the ingestion capability of phagocytes from 18 to 32 dpi. Enterococci/enterocins therapy prevented a reduction in cells with respiratory burst caused by T. spiralis infection from 11 dpi. The enzymatic activity of phagocytes was stimulated on 18 and 25 dpi, particularly by E. faecium CCM8558 and enterocin M. Enterocin M and the durancin-like enterocin were as effective in stimulating phagocytosis as the bacterial strains that produce them. The stimulation of phagocytosis could contribute to decreased larval migration and reduced parasite burden in the host.

Modulation of lymphocyte subpopulations in the small intestine of mice treated with probiotic bacterial strains and infected with Trichinella spiralis.

AIMS: To study the local intestinal lymphocyte immunity in mice with trichinellosis affected by probiotic bacteria. METHODS AND RESULTS: Enterococcus faecium CCM8558, Enterococcus durans ED26E/7, Limosilactobacillus fermentum CCM7421 and Lactiplantibacillus plantarum 17 L/1 were administered daily (109  CFU ml-1 ) and mice were infected with Trichinella spiralis (400 larvae) on the 7th day of treatment. T. spiralis infection significantly inhibited lymphocyte subpopulations from 5 to 25 days postinfection (dpi). L. fermentum CCM7421 and L. plantarum 17 L/1 restored the CD4+ T cell numbers in the epithelium and lamina propria at the control level from 11 dpi. All strains stimulated the CD8+ T cells numbers in infected mice, which were restored in the lamina propria on 11 dpi and in the epithelium only on 32 dpi. B cells (CD19+ ) inhibition after T. spiralis infection was not affected by treatment till 25 dpi. CONCLUSIONS: The strain-specific immunomodulatory effect of tested bacteria was confirmed. L. fermentum CCM7421 and L. plantarum 17 L/1 showed the greatest immunomodulatory potential on CD4+ and CD8+ T lymphocytes in trichinellosis. E. faecium CCM8558 and E. durans ED26E/7 activated only CD8+ T cells in the lamina propria. SIGNIFICANCE AND IMPACT OF THE STUDY: Positive modulation of the gut lymphocyte immunity in T. spiralis infection with bacterial strains showed their beneficial effect with the host's antiparasitic defence.

Cellular and humoral peritoneal immunity to Mesocestoides vogae metacestode infection in mice.

BACKGROUND: Here, Mesocestoides (M.) vogae infection in mice is proposed as a suitable experimental model for studying the immunity in the peritoneal cavity of mice. METHODS: To investigate the kinetics of immune parameters in M. vogae-infected mice, we detected, using flow cytometry, the expression of selected lymphoid and myeloid markers within the peritoneal cell population at day 0, 3, 6, 10, 14, 19, 25, 30 and 35 post-infection. Then, using ELISA, we analyzed the cytokine IFN-γ, TGF-ß, IL-4 and IL-10 responses and the levels of anti-M. vogae IgG and IgM antibodies in the peritoneal lavage fluid. Cells isolated from the peritoneal cavity were subjected to further molecular analysis. To assess cell activation, peritoneal cells were exposed to LPS, and culture supernatants were collected and assayed for the level of cytokines and production of nitrite. Ly6C+ and Ly6G+ cells were isolated using MACS from the peritoneal cells at day 35 post-infection. Both MACS-isolated subsets were co-cultured with preactivated T cells to measure their suppressive capacity. Next, the role of parasite excretory-secretory antigens in induction of CD11b+ myeloid cells with the suppressive phenotype and the production of IL-10 was examined. RESULTS: In the peritoneal cavity an initial increase of CD11b+Gr-1+F4/80highMHC IIhigh cells, NK, NKT cells and CD8+ cytotoxic T cells was observed in the first week of infection. At day 14 post-infection, an increase in the number of myeloid CD11b+Gr-1+ cells was detected, and most of this cell population expressed low levels of F4/80 and MHC II in later stages of infection, suggesting the impairment of antigen-presenting cell functions, probably through the excretory-secretory molecules. Moreover, we confirmed that peritoneal Gr1+ cells (Ly6C+ and Ly6G+ population) are phenotypically and functionally consistent with myeloid-derived suppressor cells. Metacestode infection elicited high levels of IL-10 and upregulated STAT-3 in peritoneal cells. A higher level of IgM suggests that this isotype may be predominant and is involved in the host protection. CONCLUSIONS: Mesocestoides vogae tetrathyridia induced the recruitment of immunosuppressive cell subsets, which may play a key role in the downregulation of immune response in long-term parasitic diseases, and excretory-secretory antigens seem to be the main regulatory factor.