Probiotic strains Bifidobacterium animalis ssp. lactis HY8002 and Lactobacillus plantarum HY7717 improved immunosuppression in cyclophosphamide-treated mice

Previous studies reported that <italic>Bifidobacterium animalis</italic> ssp. <italic>lactis</italic> HY8002 (HY8002) improved intestinal integrity and had immunomodulatory effects. <italic>Lactobacillus plantarum</italic> HY7717 (HY7717) was screened <italic>in vitro</italic> from among 21 other lactic acid bacteria (LAB) and demonstrated nitric oxide (NO) production. The aims of this study were to investigate the individual and synergistic <italic>ex vivo</italic> and <italic>in vivo</italic> effects of LAB strains HY8002 and HY7717 at immunostimulating mice that have been challenged with an immunosuppressant drug. The combination of HY8002 and HY7717 increased the secretion of cytokines such as interferon (IFN)-γ, interleukin (IL)-12, and tumor necrosis factor (TNF)-α in splenocytes. In a mouse cyclophosphamide (CTX)-induced immunosuppression model, administration of the foregoing LAB combination improved the splenic and hematological indices, activated natural killer (NK) cells, and up-regulated plasma immunoglobulins and cytokines. Moreover, this combination treatment increased Toll-like receptor 2 (TLR2) expression. The ability of the combination treatment to upregulate IFN-γ and TNF-α in the splenocytes was inhibited by anti-TLR2 antibody. Hence, the immune responses stimulated by the combination of HY8002 and HY7717 are associated with TLR2 activation. The preceding findings suggest that the combination of the HY8002 and HY7717 LAB strains could prove to be a beneficial and efficacious immunostimulant probiotic supplement.