A highly selective inhibitor of Rho-associated coiled-coil forming protein kinase, Y-27632, prolongs cardiac allograft survival of the BALB/c-to-C3H/He mouse model.
BACKGROUND
Current studies provide evidence that a small G protein, RhoAp21, and its target protein, Rho-associated coiled-coil forming protein kinase (ROCK), regulate not only cell shape but also cell migration. However, contribution of Rho/ROCK signaling to graft rejection is unknown. The purpose of this study was to evaluate the inhibitory effect of Y-27632, a highly selective ROCK inhibitor, on rejection of heterotopic cardiac transplantation in mice.


METHODS
BALB/c (H-2(d)) hearts were transplanted into C3H/He (H-2(k)) as allografts that were full histoincompatibility combinations. The recipients received several doses of Y-27632, commencing 1 day before cardiac transplantation until rejection. We used immunohistochemical study to detect the expression of myocardial intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), and we immunoenzymatically measured serum interleukin (IL)-6. Furthermore, we evaluated cardiac allograft vasculopathy treated with either FK506 or Y-27632 at Day 100.


RESULTS
The Y-27632-treated (2 mg/kg/day) allografts prolonged the mean survival time (49.6 +/- 10.1 days, n = 12) as compared with the untreated allografts (8.1 +/- 0.4 days, n = 7, p < 0.001). Histologic examinations of the Y-27632-treated allografts at Day 7 showed greatly reduced leukocyte infiltration compared with the untreated allografts. The Y-27632-treated allografts revealed faint expression of myocardial ICAM-1 and VCAM-1 at Day 7. The serum IL-6 levels also decreased in the Y-27632-treated mice. In the long-surviving Y-27632-treated allografts at Day 100, we saw neither active rejection nor apparent thickening of vascular intima.


CONCLUSIONS
Our results suggest that ROCK plays a major role in cardiac rejection in the BALB/c-to-C3H/He mouse model. Inhibition of this Rho/ROCK signaling may be an alternative therapeutic option for managing acute and chronic rejection.
Ohki
S
S
Second Department of Surgery, Gunma University School of Medicine, Maebashi, Gunma, Japan.
Iizuka
K
K
Ishikawa
S
S
Kano
M
M
Dobashi
K
K
Yoshii
A
A
Shimizu
Y
Y
Mori
M
M
Morishita
Y
Y
D000577:Amides / Q000037:antagonists & inhibitors*; D000818:Animals; D000906:Antibodies / Q000187:drug effects / Q000276:immunology; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D006084:Graft Rejection / Q000188:drug therapy / Q000401:mortality; D006085:Graft Survival / Q000187:drug effects; D016027:Heart Transplantation / Q000276:immunology / Q000401:mortality* / Q000473:pathology; D007150:Immunohistochemistry; D018799:Intercellular Adhesion Molecule-1 / Q000187:drug effects / Q000276:immunology; D015850:Interleukin-6 / Q000097:blood; D007962:Leukocytes / Q000187:drug effects / Q000276:immunology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008955:Models, Cardiovascular; D011725:Pyridines / Q000037:antagonists & inhibitors*; D016042:Transplantation, Heterotopic / Q000401:mortality* / Q000473:pathology; D014184:Transplantation, Homologous; D019010:Vascular Cell Adhesion Molecule-1 / Q000187:drug effects / Q000276:immunology
D000577:Amides; D000906:Antibodies; D004791:Enzyme Inhibitors; D015850:Interleukin-6; D011725:Pyridines; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1; C108830:Y 27632