The Experimental Study On Anti-Tumor Effects Of Lipoteichoic Acid Of Bifidobacterium In Combination With 5-Fluorouracil

Chemotherapy is a common clinical choice for tumor utility therapy, but the long-term application of chemotherapy is limited because of its tox-side effects obviously. Bifidobacterium is an important normal physiological bacterium in human and animal colon. Lipoteichoic acid of Bifidobacterium(BLTA) had been reported to have the anti-tumor and positive immuno-regulation effects, but the anti-tumor effects of BLTA combined with chemotherapy and related mechanisms are still unclear. Thus the study established the hepatoma model of Balb/c mice with murine hepatoma-22 (H22) cells, investigated the therapeutic efficacy of BLTA in combination with 5-FU treatment and the effects of BLTA on immunological regulation of organism, and explored its mechanisms.In order to provide the basis of theory and experiment for elevating clinical effect of anti-tumor therapy.In this study, tumor-bearing mice were treated with 5-FU alone, BLTA alone or BLTA in combination with 5-FU. The general status and tumor size were observed and measured regularly. The growth inhibiting rate(IR) of tumor, spleen index(SI), thymus index(TI), counts of blood leucocyte and erythrocyte were detected. HE staining was used to analyze the histologic change of tumor. MTT assay was used to evaluate the proliferation of T lymphocytes and cytotoxic activities of NK cells and CTLs. ELISA was used to detect the change of IFN-γ. FCM was used to detect the lymphocyte subgroup ratio of spleen cells from tumor-bearing mice. Expression changes of mRNA and proteins of Foxp3 and TIM-3 were detected by RT-PCR and Western blot in tumor tissue from tumor-bearing mice.Both 5-FU and BLTA had inhibition effect on tumor-growth. The general status of mice treated with 5-FU alone was poor, while in the group of 5-FU in combination with BLTA, not only the inhibition of tumor growth was more significant, but also the general status of mice was well improved, with increased count of blood leucocyte, SI and TI. A lot of lymphocytes could be observed under optic microscopy in BLTA group. In NS control group, the ratio of CD4+CD25+Treg in spleen cells was high, with the mRNA and proteins high expression of Foxp3 and TIM-3 in tumor tissue.While in BLTA group or 5-FU group, CD4+CD25+Treg ratio was degraded ,with down regulation mRNA and proteins expression of Foxp3 and TIM-3.The effects was more significant in the group of BLTA combined with 5-FU. But in 5-FU group, the level of T lymphocyte proliferation, IFN-γsecretion and CD4+ T cells ratio of spleen cells were also decreased, with degraded cytotoxic activities of NK cells and CTLs, while they were significantly increased in BLTA group.The results above suggested that BLTA in combination with 5-FU could enhance anti-tumor effect and relieve the immunosuppression. The present study indicated that BLTA is effective in enhancing the efficacy and reducing the toxicity of chemotherapy. The mechanism may be that BLTA could inhibit TIM-3/TIM-3L pathway, degrade immunosuppressive activities of CD4+CD25+Treg, improve the level of T lymphocyte proliferation and IFN-γsecretion, enhance cytotoxic activities of NK cells and CTLs in order to improve hostself tumor immunity and relieve side- effect of chemotherapy.