Intragraft gene expression profile associated with the induction of tolerance by allochimeric MHC I in the rat heart transplantation model

Abstract

The MHC class I allochimeric protein containing donor-type epitopes on recipient-type heavy chains induces indefinite survival of heterotopic cardiac allografts in rats. We analyzed gene expression profile of heart allograft tissue. Mutated peptide [alpha1h1/u]-RT1.Aa that contains donor-type (Wistar Furth, WF; RT1u) immunogenic epitopes displayed on recipient-type (ACI, RT1a) was delivered into ACI recipients of WF hearts at the time of transplantation in addition to a 3 days course of oral cyclosporine. Microarray analysis was performed using Affymetrix Rat 230 2.0 Microarray. Allochimeric molecule treatment caused upregulation of genes involved in structural integrity of heart muscle, downregulation of IL-1beta a key modulator of the immune response, and downregulation of partitioning defective six homolog gamma PAR6, which is involved in T cell polarity, motility, and ability to scan dendritic cells (DC). These indicate that the immunosuppressive function of allochimeric molecule and/or the establishment of allograft tolerance depend on the induction of genes responsible for the heart tissue integrity, the suppression of cytokine pathway(s), and possibly the impairment of T cells mobility and their DC scanning ability. These novel findings may have important clinical implications for inhibition of chronic rejection in transplant recipients.

Allochimeric MHC I-Conditioned T Cells Attenuate Chronic Rejection in Rat Cardiac Model System

“…Our previous studies in rat cardiac model system demonstrated that the peri-operative treatment of recipients with an allochimeric MHC I abrogated acute and chronic rejection of the allograft, decreased perivascular inflammation, concentric vascular intimal hyperplasia, necrotizing arteritis and progressive luminal narrowing [7]. We also showed that allochimeric MHC I treatment caused the inhibition of T cell migration into the graft, restriction of their Vβ-TCR repertoire [3], and induced changes in T cell actin cytoskeleton and down-regulation of numerous molecules involved in actin organization (RhoA, HIPP55), cell polarity (PAR6) and intracellular antigen trafficking (KDEL, GM130; [8][9][10][11]. graft injury and the role of Tregs in the maintenance of tolerance and in the attenuation of chronic rejection.…”

Rock1 Inhibitor Abrogates Chronic Rejection in Rat Cardiac Model System

“…In spite of the decades of extensive studies on the phenomenon of allograft rejection, the understanding of the mechanisms underlying the development of chronic re-jection and the ability to inhibit this process are far from being successful. Our previous studies using rat cardiac allograft model system indicated that the abrogation of chronic rejection involves inhibition of T cell migration into the graft, promotes development of Tregs, and, at the molecular level, correlates with a down regulation of RhoA pathway components and dis-regulation of its actin cytoskeleton targets [10][11][12][13][14]. Here we showed that the treatment with the Y-27632, a highly selective inhibitor of the RhoA protein kinase ROCK1 abrogates chronic rejection of the rat cardiac allografts.…”

“…Adult male inbred Wistar Furth (WF; RT1.A u ) and ACI (RT1.A a ) rats were purchased from Harlan Sprague Dawley (Indianapolis, IN) and housed in standard rat cages. Heterotopic cardiac transplants were placed intraabdominally as described previously [6][7][8][9][10][11][12][13][14][15]. Transplantation was performed as follows: 1) transplantation control group that received no treatment; 2) transplantation in the presence of high dose cyclosporine (CsA) delivered by gavage feed (10 mg/kg, day 0 -6); 3) transplantation in the presence of sub-therapeutic dose of CsA delivered by gavage (10 mg/kg, day 0 -2); 4) transplantation in the presence of Y-27632 inhibitor (Fisher Scientific, 2 mg/kg, day 0 -6) delivered by gavage; and 5) transplantation in the presence of sub-therapeutic dose of CsA (10 mg/kg, day 0 -2) in conjunction with Y-27632 inhibitor (2 mg/kg) which was gavage fed as a single dose before the transplantation.…”

“…Targeting of such molecules would provide a clear path to clinical utility. Recently, we showed that allochimeric MHC I treatment induced down-regulation of RhoA pathway components (RhoA and ROCK-1) involved in actin cytoskeleton organization and cell motility, caused the inhibition of T cell migration into the graft [11][12][13][14] and restriction of the TCR repertoire [15]. Proper actin cytoskeleton architecture and dynamics, indispensable for events in the immunological response such as T cell interaction with antigen presenting cells, activation, migration and redistribution of T cell receptors [16][17][18][19][20][21][22][23] are regulated by proteins belonging to the superfamily of small GTP-binding proteins, such as RhoA GTPase and its downstream target, the RhoA kinase (ROCK) [24][25][26][27][28][29][30][31].…”

“…Proper actin cytoskeleton architecture and dynamics, indispensable for events in the immunological response such as T cell interaction with antigen presenting cells, activation, migration and redistribution of T cell receptors [16][17][18][19][20][21][22][23] are regulated by proteins belonging to the superfamily of small GTP-binding proteins, such as RhoA GTPase and its downstream target, the RhoA kinase (ROCK) [24][25][26][27][28][29][30][31]. Our finding that in rat cardiac allograft model system the immunosuppressive and anti-chronic rejection activity of the allochimeric molecule was achieved via down regulation of the RhoA pathway-and cytoskeleton-dependent T cell functions [11,13,14] suggested that a RhoA pathway inhibitor(s) could be a potential therapeutic agent(s) for the inhibition of chronic rejection of the grafts. Thus, we tested the ability of the Y-27632, a highly selective, commercially available, inhibitor of Rho-associated protein kinase p160ROCK (ROCK1) [32,33], to abrogate chronic rejection in rat cardiac allografts.…”