The immunomodulatory effects of lactic acid bacteria have been demonstrated previously. In this study, a Lactobacillus plantarum strain was selected and enriched with
selenium nanoparticles for use as a new immunomodulating agent in a
breast cancer murine model. 30 female inbred BALB/c mice were equally divided into a test group and a control group. For 2 weeks prior to
tumor induction, each mouse received a daily
oral administration of 2.5×108 CFU/ml of L. plantarum enriched with
selenium nanoparticles (SeNPs), and then 1×106 4T1 cells were injected subcutaneously. After
tumor induction, daily
SeNP administration was repeated for 3 cycles of 7 days on/3 days off. Immunological parameters such as levels of
cytokines, NK cell activity,
tumor growth, and mouse survival were evaluated. The production of the pro-inflammatory
cytokines IFN-γ, TNF-α, and
IL-2 in spleen cell cultures was increased in test mice administered
SeNP-enriched L. plantarum. The test mice also showed significant increases in NK cell activity. The
tumor volumes of treated mice were decreased and their survival rate notably increased when compared to mice that received L. plantarum alone or control mice. Administration of
SeNP-enriched L. plantarum can induce an efficient immune response through the elevation of the pro-inflammatory
cytokines IFN-γ, TNF-α and
IL-2 levels and increased NK cell activity. Therefore, this treatment may result in better
cancer prognosis.