The Effects Of Cell Components Of L.casei LC2W On Cytokine Expression And Activity Of Murine Macrophage RAW264.7 Cells

As an important member of intestinal indigenous microflora, Lactobacilli exert critical physiological impacts on host health including resisting pathogen colonization, adjusting microecology balance, anti-tumor forming, improving host defense and immune system. It is reported the immunomodulatory activity of lactobacilli is predominantly derived from its cell wall, which are ubiquitous in Gram positive bacteria. Although the immunomodulatory activity of Lactic acid bacteria had been widely recognized, the immunogenic of the bacteria was regarded as strain-specific based on the evidence obtained so far. e.g. Lb. plantarum and Lb.rhamnosus had already been extensively investigated for their immunogenic properites and proved to be potential new nonspecific immunity enhancers. In this paper, the cell lysate, crude cell wall, cytoplasm and exopolysaccharide of Lb.casei LC2W were extracted and their effects on a murine macrophage cell line RAW264.7 in aspects of macrophage stimulation and activation, cytokine expression in vitro were reported.Lb.casei LC2W was cultured in MRS broth at 37oC and then the bacteria cells in the late-log-phase were collected. Washed bacterial cells were broken by high-pressure treatment, with protein, DNA and RNA depleted effectively by treatment with SDS and enzyme, e.g. trypsin and DNase, RNase. Then the immunomodulatory effects of L.casei LC2W were assessed in vitro via surveying their impacts on activities of macrophage cells, employing the cultured murine macrophage cell line RAW264.7 as subjects.As an important component of host innate immunity, activitation and stimulation of macrophages was the first and critical step in inducing immune response in host, only activated macrophage can have immune funtion. So the MTT energy metabolism level of RAW264.7 macrophage was observed in the paper. It was showed that cell activity of RAW264.7 macrophage did not changed obviously. It suggested that the cell lysate, crude cell wall, cytoplasm of L.casei LC2W did not affect RAW264.7 cell viability.The expression of cytokine TNF-α,IFN-γ,IL-12 were enhanced effectively after stimulated by cell lysate, crude cell wall, cytoplasm of L.casei LC2W from 10μg/ml to 80μg/ml, also in a dosage-dependent manner.TNF-α,IFN-γand IL-12 expression induced by LPS was inhibited, whereas IL-10 production was significantly enhanced in a dosage-dependent manner, in murine macrophage RAW264.7 cells challenged with different levels of exopolysaccharides produced by L.casei LC2W. These results suggested that exopolysaccharides produced by L.casei LC2W might possess a potential anti-inflammatory effect.