sotrastaurin and Reperfusion-Injury

Prolonged cold preservation frequently causes delayed renal graft function resulting from tubular epithelial injury. Inhibition of signal transduction downstream from protein kinase C (PKC) may reduce renal ischemia-reperfusion injury and confer renal graft protection. We therefore evaluated the effect of sotrastaurin, a small-molecule inhibitor of Ca²⁺-dependent and Ca²⁺-independent PKC isoforms, in comparison with mycophenolic acid (MPA) on rat renal transplants with prolonged cold preservation.. Donor kidneys from male Lewis rats were cold stored in University of Wisconsin solution for 24 hr before syngeneic grafting. Recipients received sotrastaurin (30 mg/kg twice daily), MPA (20 mg/kg/day), or vehicle through gavage starting 1 hr after surgery. Renal function was evaluated by serum creatinine and histology on day 2 (acute injury) and day 7 (repair phase) after transplantation. Postreperfusion inflammation was determined by real-time polymerase chain reaction of proinflammatory genes and histology. Signaling mechanisms were studied by Western blotting and immunohistochemistry.. Sotrastaurin enhanced immediate transplant function, attenuated epithelial injury, and accelerated renal function recovery compared with MPA. Despite the stronger anti-inflammatory capacity of MPA, only sotrastaurin treatment achieved significant cellular protection with persisting reduced apoptosis of tubular epithelial cells. Decreased phosphorylation of extracellular signal-regulated protein kinase and p66Shc adaptor protein, both involved in cellular stress and apoptosis, were likely the responsible mechanism of action.. The PKC inhibitor sotrastaurin effectively ameliorated ischemia-reperfusion organ damage and promoted cytoprotection in a clinically relevant model of extended renal cold preservation followed by transplantation. Pharmacologic targeting of PKC may be beneficial for recipients receiving renal transplants at risk for delayed graft function.

Topics: Adenosine; Allopurinol; Animals; Apoptosis; Biomarkers; Blotting, Western; Cell Proliferation; Cold Temperature; Creatinine; Cytokines; Cytoprotection; Delayed Graft Function; Glutathione; Immunohistochemistry; Inflammation Mediators; Insulin; Kidney; Kidney Transplantation; Male; Mycophenolic Acid; Organ Preservation; Organ Preservation Solutions; Protein Kinase C; Protein Kinase Inhibitors; Pyrroles; Quinazolines; Raffinose; Rats; Rats, Inbred Lew; Real-Time Polymerase Chain Reaction; Reperfusion Injury; Signal Transduction; Time Factors

Sotraustaurin (STN), a small molecule, targeted protein kinase C (PKC) inhibitor that prevents T-lymphocyte activation via a calcineurin-independent pathway, is currently being tested in Phase II renal and liver transplantation clinical trials. We have documented the key role of activated T cells in the inflammation cascade leading to liver ischemia/reperfusion injury (IRI). This study explores putative cytoprotective functions of STN in a clinically relevant rat model of hepatic cold ischemia followed by orthotopic liver transplantation (OLT). Livers from Sprague-Dawley rats were stored for 30 h at 4°C in UW solution, and then transplanted to syngeneic recipients. STN treatment of liver donors/recipients or recipients only prolonged OLT survival to >90% (vs. 40% in controls), decreased hepatocellular damage and improved histological features of IRI. STN treatment decreased activation of T cells, and diminished macrophage/neutrophil accumulation in OLTs. These beneficial effects were accompanied by diminished apoptosis, NF-κB/ERK signaling, depressed proapoptotic cleaved caspase-3, yet upregulated antiapoptotic Bcl-2/Bcl-xl and hepatic cell proliferation. In vitro, STN decreased PKCθ/IκBα activation and IL-2/IFN-γ production in ConA-stimulated spleen T cells, and diminished TNF-α/IL-1β in macrophage-T cell cocultures. This study documents positive effects of STN on liver IRI in OLT rat model that may translate as an additional benefit of STN in clinical liver transplantation.

Topics: Animals; Apoptosis; Cell Proliferation; Cold Ischemia; Extracellular Signal-Regulated MAP Kinases; Hepatocytes; Liver Transplantation; Male; NF-kappa B; Protein Kinase C; Pyrroles; Quinazolines; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Signal Transduction; T-Lymphocytes