摘要：We previously reported that the immunostimulatory activity of heat-killed
Latilactobacillus sakei K040706 in macrophages and cyclophosphamide (CTX)-treated mice. However, identification of heat-killed
L. sakei K040706 (heat-killed LS06) using a validated method is not yet reported. Further, the underlying molecular mechanisms for its immunostimulatory effects in CTX-induced immunosuppressed mice remain unknown. In this study, we developed strain-specific genetic markers to detect heat-killed
L. sakei LS06. The lower detection limit of the validated primer set was 2.1 × 10
5 colony forming units (CFU)/mL for the heat-killed LS06 assay. Moreover, oral administration of heat-killed LS06 (10
8 or 10
9 CFU/day, p.o.) effectively improved the body loss, thymus index, natural killer cell activity, granzyme B production, and T and B cell proliferation in CTX-treated mice. In addition, heat-killed LS06 enhanced CTX-reduced immune-related cytokine (interferon-γ, interleukin (IL)-2, and IL-12) production and mRNA expression. Heat-killed LS06 also recovered CTX-altered microbiota composition, including the phylum levels of Bacteroidetes, Firmicutes, and Proteobacteria and the family levels of
Muribaculaceae,
Prevotellaceae,
Tannerellaceae,
Christensenellaceae,
Gracilibacteraceae, and
Hungateiclostridiaceae. In conclusion, since heat-killed
L. sakei K040706 ameliorated CTX-induced immunosuppression and modulated gut microbiota composition, they have the potential to be used in functional foods for immune regulation.
