Mechanism of immunomodulation by Lactobacillus paracasei subsp. paracasei NTU 101 in mice model
Date Issued
2011
Date
2011
Author(s)
Tsai, Yueh-Ting
Abstract
Many Lactobacillus species regulate the immune responses, benefits in the protection of host organisms against a wide variety of enteropathogens, but the mechanisms of immunomodulation are still unknown. This study was investigated the immunomodulation in SPF BALB/c mice by diet with 108 colony forming units (CFU) of L. paracasei subsp. paracasei NTU 101.
The first section described the possible time-dependent role of L. paracasei subsp. paracasei NTU 101 in immunomodulation was investigated in BALB/c mice fed daily with 108 CFU of L. paracasei subsp. paracasei NTU 101 for 3, 6, and 9 weeks, and following feeding with Lactobacillus-free food for a further 7 days. We observed up-regulation of the antigen-presenting ability of dendritic cells, and expression of natural killer group-2 D (NKG2D) molecules capable of trigger natural killer cell-mediated cytotoxicity. Lymphocyte proliferation and antibody production were also significantly increased in mice after treatment. Innate and adaptive immunity remained constant even at the most protracted feeding time, indicative of the time dependence of the bacterial-mediated enhanced immunity. To better correlate intestinal microflora with immunity, the intestinal contents of probiotics and harmful microorganisms were determined. Results showed an altered intestinal microflora, with increases in bifidobacteria and lactobacilli and a decreased content of Clostridium perfringens after feeding with L. paracasei subsp. paracasei NTU 101. It is possible that persistent activation of immunity might be induced by intestinal probiotics.
The role of lactic acid bacteria in gut mucosal immunity was investigated by comparing the enhanced effects in the Peyer’s patches and spleen of BALB/c mice fed daily with L. paracasei subsp. paracasei NTU 101 for 3 , 6, and 9 weeks. After feeding with Lactobacillus, Peyer’s patches exhibited a more distinct capacity to induce CD4+ T cell-dendritic cell interactions, lymphocyte proliferation, and cytokine secretion than the spleen, and thereby promoted greater intestinal IgA production that could enhance gut mucosal immunity.
This study investigated the immunomodulation of Lactobacillus against enterohemorrhagic Escherichia coli O157:H7 infection in a BALB/c mice models. Mice were fed with L. paracasei subsp. paracasei NTU 101 for 7 days, before and after challenge with E. coli O157:H7. We observed up-regulation of the antigen-presenting ability of dendritic cells, helper T cell activation, and antibody production in post- and pre-treated mice, compared with untreated mice in the E. coli O157:H7 infection group. Moreover, Lactobacillus can increased post-challenge body weight gain and lower cumulative morbidity rates, down-regulate the expression of TLRs on macrophage, proinflammatory cytokines, and chemokines in the post- or pre-treated mice induced by E. coli O157:H7. We observed a greater enhancement in the immunity and inhibition of inflammation among the mice in the pre-treated group than in the post-treated group. These results demonstrated that feeding mice L. paracasei subsp. paracasei NTU 101 could reduce the severity of E. coli O157:H7 infection by modulating their immune response. The results also suggested that dietary supplementation with Lactobacillus strain could have a significant impact on immunological responses. The benefits were more significant when administered before rather than after infection.
These studies, which represent the first report of the enhancement of immunity by Lactobacillus in time-dependent manner, exhibited a more distinct capacity of immunomodulation in secondary lymphoid tissue, and reduce the severity of E. coli O157:H7 infection by modulating their immune response. The results also suggested that dietary supplementation with Lactobacillus strain could have a significant impact on immunological responses. Therefore, application of L. paracasei subsp. paracasei NTU 101 may be an effective candidate for use as a probiotic in the prevention of gastrointestinal infection in humans, the more appropriate application worthy to be studied in the future.
Subjects
Lactobacillus
enterohemorrhagic E. coli O157:H7
Innate immunity
gut mucosal immunity
Peyer’s patches
Type
thesis
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