Modulatory Effect of Probiotic Therapy on Intestinal Lymphocytes in Mice Infected with Trichinella spiralis
Important components of the intestinal mucosal immunity are free intraepithelial and lamina propria lymphocytes involved in the regulation and activity of the immune response. This study detected the presence of helper CD4 and cytotoxic CD8 T lymphocytes, and B lymphocytes in the small intestine of mice treated with probiotic strains and infected with Trichinella spiralis. Bacterial strains of different origin (Enterococcus faecium CCM8558, Enterococcus durans ED26E/7, Lactobacillus fermentum CCM7421, Lactobacillus plantarum 17L/1) were administered daily in dose of 10<sup>9</sup>CFU/ ml in 100 μl and mice were infected with 400 larvae of T. spiralis on 7<sup>th</sup> day of treatment. L. fermentum CCM7421 and L. plantarum 17L/1 increased numbers of helper CD4 T cells in the epithelium and cytotoxic CD8 T cells in the lamina propria on 7<sup>th</sup> day of administration (before parasitic infection). T. spiralis infection caused a significant inhibition of examined lymphocyte subpopulations from 5 to 25 days post infection (p.i.). Lactobacilli restored the CD4 T cell numbers in the epithelium and lamina propria on the level of healthy control from day 11 p.i. All strains stimulated the numbers of CD8 T cells in infected mice, but in comparison to control, CD8 T cells were reduced in the epithelium until day 25 p.i. and in the lamina propria only on day 5 p.i. An inhibition of B cells (CD19) in the small intestine after T. spiralis infection was not affected by probiotic therapy till day 25 p.i., but a stimulation of B cells was found after treatment with E. durans ED26E/7 and L. fermentum CCM7421on day 32 p.i. The obtained results confirmed the strain-specific immunomodulatory effect of probiotic bacteria. The greatest immunomodulatory potential on the gut CD4 and CD8 T lymphocytes during T. spiralis infection was confirmed by L. fermentum CCM7421 and L. plantarum 17L/1. Strains E. faecium CCM8558 and E. durans ED26E/7 activated only cytotoxic CD8 T cells in the lamina propria.