Abstract
Objective. The range of peptide drugs is expanding, but no drug with immunosuppressive activity has yet been found. Considering the fact that the trophoblastic β1-glycoprotein (PSG) is a fetoplacental protein with immunosuppressive activity, short peptide fragments of this protein were studied in the formation of an immune response in a situation of allogeneic cell transplantation. To study the effect of PSG peptides (YECE, YQCE, YVCS, and YACS) on the levels of peripheral and local T-regulatory cells (Treg) during the formation of an immune response to the introduction of allogeneic bone marrow cells (BM) in a dynamic experiment on Wistar rats.
Materials and methods. We used an original host-versus-graft model in male Wistar rats without preconditioning of recipients. Animals were injected with PSG peptide fragment composition against a background of allogeneic intraperitoneal transplantation of BM cells in a dynamic experiment, in which the following parameters were evaluated: the level of peripheral "true" Tregs (CD4+CD25+FOXP3+), CD4+CD25-FOXP3+ cells, and FOXP3 expression in mesenteric lymph nodes. Material was collected on days 3 and 21 of the experiment.
Results. PSG peptide administration against a background of allogeneic BM cells was found to reduce the absolute and relative amount of Treg in the peripheral blood of rats on days 3 and 21 of the experiment. PSG peptides against the background of the introduction of allogeneic BM cells reduced the absolute and relative amounts of CD4+CD25-FOXP3+ cells on the day 3 of the experiment. The introduction of PSG peptides against the background of the introduction of BM cells resulted in a relative decrease in FOXP3 expression in the T zone of mesenteric lymph nodes on the day 21 of the experiment.
Conclusions. Thus, the PSG peptides did not have the expected effect on the level of peripheral and local Treg cells; moreover, the presence of the peptides led to a decrease in the number of these cells.