Adjuvant therapy with probiotic bacteria increases in vivo survival and function of natural killer cells in humanized mice
Natural killer cells target and kill cancer stem cells (CSCs)/undifferentiated tumors, as well as healthy, non-transformed stem cells. Following selection, NK cells differentiate CSCs, via secreted and membrane-bound IFN-γ and TNF-α. Probiotic bacteria increase the cytokine secretion function of split anergized NK cells, causing significant induction of IFN-γ. Thus, treatment of NK cells with probiotic bacteria induces differentiation of CSCs. Additionally, probiotic bacteria, in combination with osteoclasts maintain and expand highly functional NK cells for a long period of time. This novel method of expanding a large number of highly functional NK cells may be a breakthrough strategy for adoptive NK immunotherapy. In this study, NK immunotherapy was studied in combination with supplementation of probiotic bacteria in the humanized mouse model. NK immunotherapy increased cytokine production in immune tissue of subjects, while probiotic supplementation further enhanced these effects, resulting in more differentiated tumors in vivo.