Lactobacillus johnsonii activates RAW 264.7 cells accompanied by induction of cell death

Lactobacillus is a probiotics that improves various diseases and enhances immunity through the activation of cytokines involved in natural immunity. A variety of studies on immunoregulation have been conducted on various Lactobacillus, but few on Lactobacillus johnsonii (Lj) and especially on immune cells. In this study, we investigated how Lj affects the viability and function of RAW264.7 macrophages. The results indicated that Lj decreased the metabolic activity of RAW 264.7 cells and caused a decrease in the number of cells. In Annexin V and PI staining, the viable cells was significantly decreased at 107 cfu/mL Lj concentration. Measurement of cytokines using enzyme-linked immunosorbent assay (ELISA) showed that Lj increased the production of tumor necrosis factor (TNF)-alpha. Also, Lj increased the expression of CD40 and CD86, confirmed by flow cytometry analysis. Taken together, Lj caused decreased metabolic activity and cell viability, but simultaneously increased the expression of macrophage activation markers and TNF-alpha production. Therefore, when an appropriate dosage of Lj is administered, it is expected that the necessary immunomodulation can be increased while minimizing damage on cells. This study provided evidences for the immunomodulatory effects of Lj on RAW 264.7 cells in vitro and is expected to be a valuable information for Lj research.