Enhancement of immunoregulatory effects of Lactobacillus gasseri TMC0356 by heat treatment and culture medium

Aims: The aim of this study was to investigate the influence of heat treatment and culture media on the immunoregulatory effects of a probiotic strain, Lactobacillus gasseri TMC0356 (TMC0356). Methods and Results: TMC0356 cultured in deMan-Rogosa-Sharpe and same food grade (FG) media were inactivated with the heat treatment at 70 and 90 degrees C. Viable and heat-killed TMC0356 were tested for their ability to induce interleukin (IL)-12 production in the murine macrophage cell line J774.1. These TMC0356 were examined for their resistance to N-acetylmuramidase. Their morphology was observed by scanning electron microscopy. The heat-killed TMC0356 significantly induced IL-12 production in J774.1 cells and exhibited enhanced resistance to N-acetylmuramidase compared with viable TMC0356. Morphological changes were observed in TMC0356 when cultured in FG medium. Cell morphology and induction of IL-12 production in J774.1 cells were also associated. Conclusions: These results suggest that heat treatment and culture medium composition modified the immunoregulatory effects of TMC0356 to induce IL-12 production in macrophages. Significance and Impact of the Study: These results demonstrate that probiotic immunoregulatory effects may be modified by the processing technology of cell preparation.