Liver glutathione depletion after preservation and reperfusion in human liver transplantation

Abstract

Purpose:The oxidative stress is an important mechanism responsible for dysfunction after orthotopic liver transplantation (OLT). Glutathione (GSH) low levels after cold storage render the grafts vulnerable to reperfusion injury. Aim of this study was to evaluate GSH and oxidized glutathione (GSSG) liver concentrations, the hepatocellular injury and function in optimal and suboptimal grafts after human OLT. Methods: Liver biopsies were taken in 33 patients before the implant and two hours after reperfusion, allowing determination of GSH, GSSG and oxidative stress ratio (GSH/GSSG). Serum transaminases, prothrombin activity (PT) and factor V were measured to evaluate injury and function respectively. Histopathological injury was analyzed by an index of five parameters. Results: There was a decrease in GSH (p<0.01) after reperfusion (0.323 ± 0.062 ìmol/g to 0.095 ± 0.01 ìmol/g and 0.371 ± 0.052 ìmol/g to 0.183 ± 0.046 ìmol/g) in suboptimal and optimal groups, respectively. An increase of GSSG (p<0.05) occurred after reperfusion (0.172 ± 0.038 ìmol/g to 0.278 ± 0.077 ìmol/g and 0.229 ± 0.048 ìmol/g to 0.356 ± 0.105 ìmol/g) in suboptimal and optimal groups, respectively. A decrease (p<0.01) occurred in the GSH/GSSG ratio after reperfusion (2.23 ± 0.31 to 0.482 ± 0.042 and 2.47 ± 0.32 to 0.593 ± 0.068) in suboptimal and optimal groups, respectively. Histopathological injury scores were higher (p<0.05) in the suboptimal group than in optimal (6.46 ± 0.4 vs. 5.39 ± 1.1) and showed correlation with PT and factor V in the optimal group (p<0.05). Multivariate analysis pointed steatosis as an independent risk factor to histopathological injury (p<0.05). Conclusion: There was a significant GSH depletion and GSSG formation after cold storage and reperfusion due to a similar oxidative stress in optimal and suboptimal grafts, but these levels were not related to graft viability. Key words: Liver Transplantation. Oxidative Stress. Glutathione. RESUMOObjetivo: O estresse oxidativo é um importante mecanismo responsável pela disfunção dos enxertos após transplante de fígado (TF). Sabe-se que níveis baixos de Glutationa reduzida (GSH) deixam os enxertos vulneráveis aos danos de reperfusão. O objetivo deste estudo foi avaliar as concentrações de GSH e da Glutationa oxidada (GSSG), os danos hepatocelulares e a função em enxertos ótimos e subótimos após TF. Métodos: Foram realizadas biópsias em 33 pacientes imediatamente antes do implante e duas horas após a reperfusão, permitindo a determinação do GSH, GSSG e o cálculo do índice de stress oxidativo (GSH/GSSG). Foram medidas as transaminases hepáticas e as atividades da Protrombina (TP) e do Fator V para avaliação dos danos hepatocelulares e da função do enxerto, respectivamente. O dano histopatológico foi avaliado através de um índice de cinco parâmetros. Resultados: Houve uma diminuição nos níveis de GSH (p<0.01) 0.323 ± 0.062 ìmol/g to 0.095 ± 0.01 ìmol/g and 0.371 ± 0.052 ìmol/g to 0.183 ± 0.046 ìmol/g) e aumento nos níveis de GSSG (0.172 ± 0.038 ìmol/g to 0.278 ± 0.077 ìmo...

Subnormothermic Machine Perfusion of Steatotic Livers Results in Increased Energy Charge at the Cost of Anti-Oxidant Capacity Compared to Normothermic Perfusion

“…This is in direct contrast to NMP, where γ-glutamylcysteine concentrations increase during perfusion and glutathione stores are able to be maintained. This is a clinically relevant finding given prior studies demonstrating an acute depletion of reduced glutathione stores following graft reperfusion in clinical liver transplantation studies [18,19]. Though no clinical reports of transplantation of steatotic human livers after SNMP exist, these grafts may suffer severe ischemic-reperfusion injury (IRI) at reperfusion and could potentially experience higher rates of early allograft dysfunction (EAD) or post-reperfusion syndrome (PRS) as a result of glutathione depletion.…”

Are silymarin and N‐acetylcysteine able to prevent liver damage mediated by multiple factors? Findings against ethanol plus LPS‐induced liver injury in mice

“…A group of enzymes called GST is essential for detoxification because it is involved in the biotransformation of phase II, converting endogenous water‐soluble substances to fat‐soluble ones, and catalyzing the conjugation of GSH with electrophilic substances. [ 48 ] As a result, GST participates in cellular defense against ROS, which cause oxidative stress and are linked to a variety of chronic disorders, such as liver diseases. [ 49 ] Accordingly, the activity of GST was reduced in the liver of animals exposed to ethanol and LPS and treated with the vehicle, and the same was observed in the groups treated with SIL or NAC, corroborating the reduced levels of GSH found in these groups.…”