Natural Killer Cell Activation by Weissella cibaria JW15 Isolated from Kimchi

Abstract

Natural killer (NK) cells are innate immune cells with the capacity to eliminate virus-infected and cancer cells. Therefore, enhancing NK cell activity remains a promising strategy to control viral infection and cancer development. Recent studies highlighted the immunostimulatory effect of lactic acid bacteria (LAB), especially via activation of NK cells. Among LAB, Weissella cibaria JW15, isolated from kimchi, activated splenocytes and enhanced immune responses, but whether JW15 enhanced NK cell activity was unclear. In this study, we investigated if JW15 affects NK cell activity and a possible role of exopolysaccharides (EPS) produced by JW15 in immune-stimulatory activity. Splenocytes or NK cells isolated from mice were treated with live JW15 or EPS, and then evaluated for cell surface levels of activation markers, intracellular levels of granzyme B and perforin, cytokine production, including IFN-γ, and cytotoxicity against tumor cells. Our results revealed that JW15 induced the activation of NK cells, as shown by increased NK cell cytotoxicity activity, as well as increased activation markers and IFN-γ production. In addition, EPS activated NK cells and splenocytes, leading to the secretion of various cytokines. Furthermore, oral administration of live JW15 increased NK cell cytotoxicity. Taken together, our findings suggest JW15 as a promising probiotic candidate strain with the immune-enhancing potential to prevent or treat viral infection and cancer.