Modifying immune cells using mouse bone marrow-derived cell exosomes during administration of heat-killed lactic acid bacterium .

Previously, the mechanism underlying the immunostimulatory effect of orally administered heat-killed (HkEf) mediated by exosomes secreted after intestinal macrophage phagocytosis was clarified. In the present study, mouse bone marrow-derived dendritic cells (DCs) were used as intestinal DCs. studies evaluating the response of mouse spleen cells to exosomes purified and isolated from intestinal DCs stimulated with HkEf showed a significant increase in standard DCs and plasmacytoid DCs (pDCs), indicating a positive effect on DCs, mainly pDCs, and possibly contributing to their immunostimulatory effects. The microRNAs (miRNAs) of exosome fractions derived from intestinal DCs and macrophages were also examined using bone marrow progenitor cells. HkEf stimulation released miRNA-rich exosomes, which acted as an immune response signal mediator, and increased various miRNAs other than miR-146 that are essential for refilling innate immune cells. In the present study, the effect mediated by miRNA-rich exosomes on the distant immune system from intestinal immunity (macrophages, DCs) was observed via orally administered HkEf, a preparation. The findings of the present study revealed that this mechanism can potentially prevent systemic infection.