Lactobacillus gasseri OLL2809 inhibits development of ectopic endometrial cell in peritoneal cavity via activation of NK cells in a murine endometriosis model

We have previously reported that peritoneal administration of interleukin-12 (IL-12) suppresses development of ectopic endometriotic lesions via activation of natural killer (NK) cells in a mouse endometriosis model. Lactobacillus gasseri OLL2809 is one of a probiotic lactobacillus that has been selected on an ability to stimulate production of IL-12 from murine splenocytes. In this study, we examined whether the oral administration of heat-killed L. gasseri OLL2809 suppressed development of endometriosis. Administration of L. gasseri OLL2809 for 21 consecutive days resulted in reduction of the development of ectopic endometriotic lesions in an extent similar to IL-12. Although obvious effects of L. gasseri OLL2809 on the peritoneal cytokine levels, population of peritoneal cells as well as cytotoxicity of splenic NK cells, gene expression analysis of the peritoneal cells revealed enhancement in the transcription of IL-2 and natural killer cell triggering receptor 1 genes. Therefore, it was suggested that L. gasseri OLL2809 suppressed