Ligands of NOD2 (Muramyl Dipeptide) and TLR4 (LPS) in 24 h after Combined In Vivo Administration Produce a Synergistic Increase in the Content of Multipotent Stromal Cells in the Bone Marrow and Peritoneal Exudate of CBA Mice

Effect of Immunization with Type 5 Group A Streptococcal Antigens and Liposaccharide (LPS) In Vivo and In Vitro on Splenic and Bone Marrow Multipotent Stromal Cells in Mice

The number of multipotent stromal cells (MSC) in the splenic transplants of normal CBA mice in recipients immunized with inactivated type 5 group A streptococcal vaccine decreased by 3.5-1.8 times depending on the age of the recipients in comparison with that in the transplants grafted to the control recipients. Such immunization suppressed MSC transplantability, i.e., their potency to construct and maintain specific microenvironment of initial organs. In 24 h after administration of LPS to normal mice in vivo, the MSC content in the spleen and bone marrow increased by 1.8 and 1.6 times, respectively; in immunized mice, these parameters did not increase after LPS injection. The concentration of TNFα in the culture medium of bone marrow from normal mice increased pronouncedly after treatment with LPS both in vivo and in vitro (from 0 to 16.1±2.0 and to 14.2±0.1 pg/ml, respectively), while in the culture medium of bone marrow cells from of immunized mice, this cytokine was not detected after LPS treatment. Probably, immunization of mice with antigens of type 5 group A streptococci and resulting autoimmunity diminish animal sensitivity to LPS, which is reflected by examined parameters of the stromal tissue.

Simultaneous Administration of NOD-2 (MDP) and TLP-4 (LPS) Ligands to Bone Marrow Donors 24 h before Transplantation Increases the Content of Multipotent Stromal Cells (MSCs) in Bone Marrow Grafts in CBA Mice Compared to the Total Result of Their Isolated Administration

In 3-month bone marrow transplants of CBA mice from bone marrow donors receiving single injections of TLR-4 ligand (LPS) or NOD-2 ligand (muramyl dipeptide, MDP) 24 h before transplantation, an increase in the total number of MSCs (by 2.6 and 1.9 times, respectively), as well as a slight increase in the number of nuclear cells and the mass of bone capsules (by 1.3 and 1.2 times) were observed. After combined administration of MDР and LPS to donors, the total content of MSCs in the grafts was higher by 1.6 times in comparison with the total result of their isolated administration (and by 7.2 times in comparison with the control). At the same time, the concentration of osteogenic MSCs in the grafts of all groups was almost the same and corresponded to the control level. The number of nuclear cells and the mass of bone capsules of the grafts after combined administration of LPS and MDP were close (~80%) to the sum of the results of their isolated administration. These findings suggest that activation of the stromal tissue and the success of bone marrow transplantation depend on the intensity of innate immune responses. These data can be useful for the development of optimal methods of tissue transplantation.

Combined Administration of TLR4 (LPS) and TLR3 (Poly I:C) Ligands to CBA Mice Elevates the Content of Osteogenic MSC by 1.6 Times and Increases Content of Bone Marrow MSC to Intermediate Level between Values Attained by Their Individual Administration

In 1 and 24 h after combined administration of TLR4 (LPS) and TLR3 (Poly I:C) ligands to CBA mice, the content of MSC in bone marrow increased to intermediate value between the levels attained by their individual injections. The content of osteogenic MSC assessed in 24 h postinjection corresponded to the control level in Poly I:C group, decreased in LPS group by 2.5 times relatively to the control, and increased by 1.6 times (relatively to control) after combined administration of the ligands. In 3 h after combined addition of LPS and Poly I:C in vitro to 12-day-old primary culture of mouse bone marrow stromal cells, the concentration of TNFα in culture medium was intermediate between the levels attained by their individual application. The data revealed dependence of activation of stromal tissue on intensity of innate immunity reactions; they also attested to marked elevation of osteogenicity of MSC pool after costimulation with Poly I:C and LPS, which can underlie augmented calcification of the tissues during combined viral and bacterial infections.