Proteasome Expression in Ovarian Heterotopic Allografts of Wistar and August Rats under Induction of Donor-Specific Tolerance

The aim of this work is to investigate the dynamics for the ovarian tissue engraftment of inbred August rats transplanted to outbred Wistar rats and vice versa on the background of the induction of donor-specific tolerance and to identify the features of proteasome pools in the surviving grafts and tissue replacing the rejected grafts in animals of both groups. By day 14 after transplantation, a slight difference in graft engraftment was revealed in studied recipients: 87% in Wistar rats and 80% in August rats. At the same time, ovarian tissue allografts with well-preserved structure and significant vascularization represented 76% in Wistar rats and only 29% in August rats on day 37. The difference revealed in the remote period is apparently connected with the special condition of the central nervous system of August rats caused by the increased content of monoamines and heat-shock protein 70. The total proteasome level on day 37 was the same both in intact donor tissue and in the surviving grafts, as well as in the tissue replacing the rejected grafts, and did not depend on the donor–recipient differences. However, the increased expression of immune proteasomes was found in the surviving tissue and tissue replacing the rejected grafts compared to intact donor tissue. The surviving grafts were enriched with proteasomes with immune subunit LMP2, and the tissue replacing the rejected grafts was enriched with proteasomes with immune subunit LMP7 equally in August and Wistar rats. In addition, the surviving grafts in both groups of animals were characterized by equally high expression of proteasome activator РА28αβ compared to the replacement and intact donor tissues. Thus, transplant proteasomes containing immune subunits LMP2, and probably associated with the activator RA28αβ, serve as one of the key factors for engraftment regardless of the genetically determined differences of the recipients.