Author(s)

Li Zhang, Malgorzata Kloc, Neelam Tejpal, Junping You, Andrea M. Cordero-Reyes, Keith A. Youker, Rafik M. Ghobrial

Department of Surgery, The Methodist Hospital.
The Methodist DeBakey Heart & Vascular Center, Houston, TX, USA.

Background: We have shown previously that the abrogation of acute and chronic rejection of rat cardiac allografts occurs through the down-regulation of RhoA pathway and involves the changes in RhoA kinase (ROCK)-dependent actin cytoskeleton and T cell motility. Here we studied the ability of the Y-27632, a highly selective inhibitor of Rho-associated protein kinase p160ROCK (ROCK1), to abrogate chronic rejection of the allograft and influence T cell infiltration. Methods: Heterotopic cardiac transplants were performed between donor Wistar Furth (WF) and ACI recipient rats. Controls received sub-therapeutic dose of cyclosporine (CsA, 10 mg/kg) for 3 days or 7 days therapeutic dose of cyclosporine. The experimental groups of ACI recipient received one preoperative dose of the Y-27632 inhibitor (2 mg/kg, gavage feed) in conjunction with the sub-therapeutic dose of CsA for 3 days or inhibitor alone for 7 days. The cardiac grafts were harvested at 100 days of post-transplantation for histological and immunohistochemical assessment of chronic rejection, vascular sclerosis, and infiltration by different T cell subtypes. Results: Cardiac allografts from recipients exposed to Y-27632 inhibitor in conjunction with sub-therapeutic dose of CsA showed drastically reduced vascular sclerosis, minimal myocardial total cellular infiltration, and were selectively infiltrated with Foxp3⁺ T regulatory (Treg) cells. Conclusions: Our novel finding that a single dose of the ROCK1 inhibitor Y-27632 attenuates chronic rejection in rat cardiac model system by promoting development of Treg cells warrants its potential as a novel therapeutic agent specific for the inhibition of chronic rejection.

Chronic Rejection; Transplantation; ROCK1; RhoA; T Cell

Zhang, L. , Kloc, M. , Tejpal, N. , You, J. , Cordero-Reyes, A. , Youker, K. and Ghobrial, R. (2012) Rock1 Inhibitor Abrogates Chronic Rejection in Rat Cardiac Model System. Open Journal of Organ Transplant Surgery, 2, 46-51. doi: 10.4236/ojots.2012.24012.