ABSTRACT
We aimed to examine the mechanism of heat-killed Enterococcus faecalis (HkEf) immunostimulatory effect when orally administered. Immunocompetent splenocytes from mice orally administered HkEf were assessed using flow cytometry. Immunocompetent cells were determined by culturing splenocytes with serum or blood derived-exosomes. In vitro studies evaluated the reaction between mouse splenocytes and exosomes purified and isolated from mice bone marrow-derived macrophages (BMDMs) treated with HkEf. Levels of dendritic cells, red pulp macrophages, and inactive NK cells were significantly higher in the HkEf-treated group. Red pulp macrophages and inactive NK cells were increased in splenocytes cultured with blood-derived exosomes from mice administered HkEf. Further, mouse splenocytes cultured with the HkEf-stimulated BMDMs-derived exosomes group had significantly higher levels of red pulp macrophages. Thus, HkEf was involved in host immunostimulation and exosomes were identified as mediators in immune response signaling. Further verification of the mechanism would be needed to fill in the gap between the present results and conclusions.
Subject(s)
Exosomes , Mice , Animals , Enterococcus faecalis , Hot Temperature , Mice, Inbred C57BL , Administration, OralABSTRACT
Bone marrow cells of 4-week-old CBA/J mice were searched for progenitors that can reconstitute CBA-type B lineage (B220+) cells after transplantation into irradiated (BALB/c x CBA/J) F(1) mice. In recipients of B lineage-committed B220+ CD117+ cells, which were CD19+ CD127+ CD25- IgM-, numbers of CBA-type B220+ cells had increased greatly by day 8 after transplantation. This increase stopped by day 10 but cell numbers remained at this level for at least 8 weeks. B-cell production in the bone marrow of B220+ CD117+ cell recipients occurred even 8 weeks after transplantation. Probably, the transplanted B-lymphoid progenitors are capable of self-renewing up to 8 weeks after transplantation. B lineage- uncommitted CD117high CD71- cells, which were B220- and included haematopoietic stem cells, could also reconstitute B lineage bone marrow cells after transplantation. Sequential development of CD117+, CD25+ and IgM+ cells in CBA-type B220+ bone marrow cells occurred 2-4 days faster in recipients of B220+ CD117+ progenitors than in recipients of CD117high CD71- progenitors, suggesting that the development of the former progenitors from the latter may take 2-4 days.
