Cirsium japonicum var. maackii fermented with Pediococcus pentosaceus induces immunostimulatory activity in RAW 264.7 cells, splenocytes and CTX-immunosuppressed mice

[Display omitted] •Cirsium japonicum var. maackii fermented using Pediococcus pentosaceus (PCJ)•PCJ stimulate the immune response in RAW264.7 by promoting the immune-related cytokines and phosphorylating the NF‐κB andMAPKsignaling pathways.•PCJ markedly produced immune-related cytokines in mouse splenocytes.•PCJ enhanced cytokine secretion in CTX-induced immunosuppressed mice.•PCJ ameliorated the gut microbiota in the immunosuppressed mice. Cirsium japonicum var. maackii (CJ), a perennial herb from the Compositae family, is a traditional antihypertensive, uretic antihepatitis, and antihemorrhagic medicine in Korea. However, CJ reported has minimal immune-enhancing effects. We investigated whether fermentation with Pediococcus pentosaceus (P. p) increases the immune efficacy of CJ through in vitro, ex vivo and in vivo. Results showed that CJ and P. p fermentation (PCJ) produced nitric oxide, induced immune-related cytokine secretion, and up-regulated the MAPK and NF-κB signaling pathways in RAW 264.7 cells. Furthermore, PCJ markedly stimulated proliferation and Th1 and Th2 response by inducing the production of cytokines in splenocytes. Oral administration of PCJ significantly alleviated cyclophosphamide (CTX)-induced immunosuppression in mice, as evidenced by increased immune-related cytokine production and improved gut microbiota. These results suggest that PCJ could have a positive impact on the development of functional food with the ability on immunomodulation and intestinal microenvironment improvement.