Evaluation of the antitumor immune responses of probiotic Bifidobacterium bifidum in human papillomavirus-induced tumor model

As of present, a number of studies have shown anti-cancer effects of different strains of probiotics, but the precise host immunological mechanisms of these antitumor effects remain unclear. Thus, the aim of current study was to investigate the preventive-therapeutic effects of oral versus intravenous administration of probiotic Bifidobacterium bifidum on immune response and tumor growth of C57BL/6 mice bearing transplanted TC-1 cell of human papillomavirus (HPV)-related tumor, expressing HPV-16 E6/E7 oncogenes. Our major findings are that the intravenous or oral administration of Bifidobacterium bifidum effectively induces antitumor immune responses and inhibits tumor growth in mice. Compared to oral route only, intravenous administration of probiotic Bifidobacterium bifidum into tumor-bearing mice leads to the activation of tumorspecific IL-12 and IFN-gamma, lymphocyte proliferation, CD8(+) cytolytic responses that control and eradicate tumor growth. These observations meant intravenous administration of probiotics is an effective anticancer approach through modulation of the immune system. The potential of probiotic Bifidobacterium bifidum as an immunomodulator in the treatment of cervical cancer could be further explored.