Modulatory Effect of Postbiotic Substances (Enterocins-like) on T-Cell-Mediated Immune Response in Trichinella spiralis-Infected Mice

Postbiotic substances produced by beneficial/probiotic strains can modulate host immunity and confer health benefits. This study evaluated immunomodulatory and antiparasitic effects of the postbiotics Enterocin M and Durancin-like, as well as their producing bacteria in mice experimentally infected with Trichinella spiralis. Enterocin M, Durancin-like, Enterococcus faecium CCM8558, and Enterococcus durans ED26E/7 were administered daily to mice, which were challenged with T. spiralis larvae on day 7 of treatment. Enterocin M and E. faecium CCM8558 stimulated splenic T- and B-cell proliferation during 5–11 days post infection (dpi), increased splenic CD3+, CD4+ and CD8+ T cells, reduced CD19+ B cells, and enhanced serum IgG2a antibodies. Enterocin M also modulated IFN-γ production with an increase at 5–11 dpi followed by suppression at 18 and 25 dpi. Durancin-like exerted weaker but measurable immunomodulatory effects than its producing strain, E. durans ED26E/7, which was detected as elevated B-cell proliferation and CD3+ and CD4+ T cells during the intestinal phase, and elevated CD8+ T-cell numbers were accompanied by the suppression of IL-10, TGF-β, and IL-4 during the muscle phase. All treatments exerted significant antiparasitic effects, confirmed by reductions in the intestinal adult worm burden by 16.3–54.5% and muscle larval counts by 22.8–55.8%. E. faecium CCM8558 produced the greatest reductions in both adult (54.5%) and larval (55.8%) counts. Overall, enterocins and their producing strains exhibited combined immunomodulatory and antiparasitic activities, highlighting their potential as complementary biological agents for the control of trichinellosis.