Anti-tumor activity of heat-killed Lactobacillus plantarum BF-LP284 on Meth-A tumor cells in BALB/c mice

Abstract

Probiotics exert numerous effects on human well-being. Here, heat-killed Lactobacillus plantarum BF-LP284 (H-Lp) was isolated as a potent immuno-modulator among 15 strains of lactobacilli in terms of TNF-α induction ability in peritoneal macrophages. In vitro TNF-α and IFN-γ induction in Peyer’s patch (PP) cells was higher when incubated with H-Lp than with live L. plantarum BF-LP284 (L-Lp). Suppression of syngeneic Meth-A tumors in a murine model by oral administration of H-Lp was also greater than that of L-Lp and of controls. H-Lp stimulated IFN-γ production in spleen cells, which displayed inhibited tumor growth in Winn assays when treated with H-Lp. Moreover, H-Lp increased the ratio of CD3⁺cells among peripheral blood mononuclear cells in Meth-A tumor-bearing mice, suggesting an H-Lp-mediated anti-tumor mechanism whereby immune cells that are activated by H-Lp in PP and acquire anti-tumor activity in the spleen migrate to tumor sites through lymphocyte homing to inhibit tumor growth.

Keywords:

• Heat-killed
• IFN-γ
• Lactobacillus plantarum
• probiotics
• TNF-α
• tumor

Acknowledgements

We are grateful for the review of this article from the clinical standpoint by Dr. Morie Sekiguchi and thank Mrs. T. Ogata for her excellent technical support.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.