Relationship between the in vitro response of dendritic cells to Lactobacillus and prevention of tumorigenesis in the mouse.
BACKGROUND
Some strains of lactobacilli stimulate immune cells, yet little is known about their potency in cancer prevention. We have previously reported that Lactobacillus casei Shirota (LcS) suppresses murine tumorigenesis through immune modulation. In this study, differences were compared among six representative strains of lactobacilli in regard to their ability to stimulate bone marrow cell-derived dendritic cells (BMDCs) in vitro and tumor suppression in vivo.


METHODS
BM-DCs were cocultured with a Lactobacillus strain in vitro, and the interleukin (IL)-12 released into the culture supernatant was measured by enzyme-linked immunosorbent assay. Tumors were chemically induced by a single subcutaneous injection of 3-methylcholanthrene (MC) in BALB/c mice. The test diets containing Lactobacillus were given from the day of the MC injection, and the tumor incidences were monitored. Peyer's patches were dissected from Lactobacillus-fed mice, and the status of c-Src, a regulator of DCs, in Peyer's patch cells was examined by Western blotting.


RESULTS
In the coculture system, L. fermentum FERM P-13857 and LcS potently elicited IL-12 production. LcS but not the other strains of lactobacilli showed tumor suppression. The inactive form of c-Src, phosphorylated at Tyr527, was dominantly detected in Peyer's patches resected from L. fermentum FERM P-13857-fed mice compared with LcS-fed mice.


CONCLUSIONS
The responses of DCs may be associated with tumor suppression by an ingested Lactobacillus strain.
Takagi
Akimitsu
A
Yakult Central Institute for Microbiological Research, 1796 Yaho, Kunitachi, Tokyo 186-8650, Japan.
Ikemura
Haruo
H
Matsuzaki
Takeshi
T
Sato
Mikiko
M
Nomoto
Koji
K
Morotomi
Masami
M
Yokokura
Teruo
T
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology*; D045744:Cell Line, Tumor; D018920:Coculture Techniques; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism; D005260:Female; D007376:Interleukin-2 / Q000378:metabolism; D007778:Lactobacillus / Q000276:immunology*; D007780:Lacticaseibacillus casei / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D009374:Neoplasms, Experimental / Q000139:chemically induced / Q000276:immunology* / Q000517:prevention & control; D010581:Peyer's Patches / Q000276:immunology; D019936:Probiotics
D007376:Interleukin-2