Immunomodulatory response in an experimental model of brain death.

Liver transplantation has come a long way and is now regarded as the gold standard treatment for end-stage liver failure. The great majority of livers utilized in transplantation come from brain-dead donors. A broad inflammatory response characterizes BD, resulting in multiorgan damage. This process is primarily mediated by cytokines, which increase the immunogenicity of the graft. In male Lewis rats, we evaluated the immune response in a BD liver donor and compared it to that of a control group. We studied two groups: Control and BD (rats subjected to BD by increasing intracranial pressure). After the induction of BD, there was an intense rise in blood pressure followed by a fall. There were no significant differences observed between the groups. Blood tissue and hepatic tissue analyzes showed an increase in plasma concentrations of liver enzymes (AST, ALT, LDH and ALP), in addition to pro-inflammatory cytokines and macrophages in liver tissue in animals submitted to BD. The current study found that BD is a multifaceted process that elicits both a systemic immune response and a local inflammatory response in liver tissue. Our findings strongly suggested that the immunogenicity of plasma and liver increased with time following BD.

Immunomodulatory effects of thalidomide in an experimental brain death liver donor model.

Brain death is characterized by a generalized inflammatory response that results in multiorgan damage. This process is mainly mediated through cytokines, which amplify graft immunogenicity. We investigated the immunological response in a brain death liver donor model and analysed the effects of thalidomide, a drug with powerful immunomodulatory properties. Brain death was induced in male Lewis rats. We studied three groups: Control (sham-operated rats in which trepanation was performed without inserting the balloon catheter), BD (rats subjected to brain death by increasing intracranial pressure) and BD + Thalid (BD rats receiving thalidomide after brain death). After 6 h, serum levels of AST, ALT, LDH, and ALP as well as systemic and hepatic levels of TNF-α, IL1-ß, IL-6, and IL-10 were analysed. We also determined the mRNA expression of MHC Class I and Class II, NF-κB, and macrophage infiltration. NF-κB was also examined by electrophoretic mobility shift assay. Thalidomide treatment significantly reduced serum levels of hepatic enzymes and TNF-α, IL-1-ß, and IL-6. These cytokines were evaluated at either the mRNA expression or protein level in liver tissue. In addition, thalidomide administration resulted in a significant reduction in macrophages, MHC Class I and Class II, and NF-κB activation. This study reveals that thalidomide significantly inhibited the immunologic response and graft immunogenicity, possibly through suppression of NF-κB activation.

Contribution of prolonged ischemia and donor age to chronic renal allograft dysfunction.

As a consequence of an advancing discrepancy between supply of suitable grafts and demand from potential recipients, less than optimal organs are increasingly being used. Although clinical studies demonstrate the involvement of various risk factors, including donor age and duration of ischemia on long-term graft outcome, their individual contribution and correlation has not been followed experimentally. After cold ischemic times of 5, 60, and 120 min, kidney allografts of 3-, 12-, and 18-mo-old Fischer 344 donors were transplanted into 3-mo-old Lewis rats. Age-related changes were examined in matched native uninephrectomized controls. Proteinuria and creatinine clearance were determined, and histologic and immunohistologic studies were assessed and quantified at the end of the observation period (20 wk). All grafts functioned satisfactorily with the exception of one graft each from 12- and 18-mo-old donors with prolonged ischemia (120 min). Functional deterioration and structural changes progressed in parallel to increasing donor age and prolonged ischemia. The impact of expanded ischemia was particularly detrimental in grafts from older donor animals. Donor age and duration of ischemia act in a synergistic manner in our model. Brief ischemic times seem of particular relevance when grafts from older donors are being used.