Immunostimulatory effects of <i>Heyndrickxia coagulans</i> SANK70258

Here, we examined the immunomodulating effects of Heyndrickxia coagulans SANK70258 (SANK70258). Mouse splenocytes treated with γ-ray-irradiated SANK70258 produced higher levels of interferon (IFN)-γ than those with 7 types of lactic acid bacteria. IFN-γ was mainly produced by natural killer (NK) cells, involving IL-12/IL-23, dendritic cells (DCs), and NF-κB signaling. SANK70258 induced the release of IL-6, IL-10, and IL-12p40 from mouse DCs and the expression of cytokine genes in the human monocyte. Cytokine release from SANK70258-treated DCs was partially reduced by the knockdown of Tlr2 or Nod2, and was abolished by Myd88 knockout. DC-stimulating components of SANK70258 were enriched in ether- and butanol-insoluble peptidoglycan-related fractions. The SANK70258 component induced high levels of immunoglobulin (Ig) A production in Peyer's patch cells, and its oral intake significantly increased intestinal IgA and IgA-expressing B cells in Peyer's patches in mice. We conclude that the SANK70258 component exhibits high activity as an immunostimulant that induces the production of IFN-γ and IgA.