Effect of the Brain-Death Process on Acute Rejection in Renal Transplantation

PP2Ac upregulates PI3K-Akt signaling and induces hepatocyte apoptosis in liver donor after brain death

Multiple research groups have demonstrated that the outcome of patients receiving liver grafts from brain death donors (DBD) is poorer when compared with patients receiving grafts from living donors. This might be due to an increased hepatocyte apoptosis induced after brain death (BD). In this work, we found that the activity of PP2A-Akt pathway is significantly increased in clinical donor ex vivo hepatocytes after BD by iTRAQ protein quantification analysis. The same results were confirmed in animal models. A time-dependent promotion of apoptosis was also found in DBD rabbit liver, as demonstrated by the increased levels of cleaved Caspase 3 and the decreased of Bcl-2. To further investigate the roles of PP2A and Akt in regulating apoptosis of hepatocytes after BD, we cultivated human liver cell line L02 with serum deprivation and hypoxia, to simulate the ischemic and hypoxic conditions of hepatocytes in DBD. Increased apoptosis and decreased viability were observed during the time in this model. Meanwhile PP2A activity and Akt activity were respectively increased and decreased. Notably, the proportion of Akt phosphorylation at Ser473 decreased, while other known targets of PP2A (p38, JNK and ERK) were not affected in terms of protein levels or phosphorylation. These results suggested that PP2A is involved in apoptotic induction of hepatocytes after brain death by specific suppression of Akt. This discovery was further confirmed with pharmaceutical and genetic methods. Our work implied potential targets for reducing liver cell apoptosis and improving organ donor quality after BD.

Peritransplant Soluble CD30 as a Risk Factor for Slow Kidney Allograft Function, Early Acute Rejection, Worse Long-Term Allograft Function, and Patients' Survival

BACKGROUND

We aimed to determine whether serum soluble CD30 (sCD30) could identify recipients at high risk for unfavorable early and late kidney transplant outcomes.

METHODS

Serum sCD30 was measured on the day of kidney transplantation and on the 4th day posttransplant. We assessed the value of these measurements in predicting delayed graft function, slow graft function (SGF), acute rejection (AR), pyelonephritis, decline of allograft function after 6 months, and graft and patient survival during 5 years of follow-up in 45 recipients.

RESULTS

We found the association between low pretransplant serum levels of sCD30 and SGF. The absence of significant decrease of sCD30 on the 4th day posttransplant was characteristic for SGF, early AR (the 8th day-6 months), late AR (>6 months), and early pyelonephritis (the 8th day-2 months). Lower pretransplant and posttransplant sCD30 predicted worse allograft function at 6 months and 2 years, respectively. Higher pretransplant sCD30 was associated with higher frequency of early AR, and worse patients' survival, but only in the recipients of deceased-donor graft. Pretransplant sCD30 also allowed to differentiate patients with early pyelonephritis and early AR.

CONCLUSIONS

Peritransplant sCD30 is useful in identifying patients at risk for unfavorable early and late transplant outcomes.

Lung transplantation from donation after cardiocirculatory death: a systematic review and meta-analysis

BACKGROUND

Lung transplantation (LTx) can extend life expectancy and enhance the quality of life for select patients with end-stage lung disease. In the setting of donor lung shortage and waiting list mortality, the interest in donation after cardiocirculatory death (DCD) is increasing. We performed a systematic review and meta-analysis to compare outcomes between DCD and conventional donation after brain death (DBD).

METHODS

PubMed, CINAHL, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Cochrane Central Register of Controlled Trials, Scopus, Web of Science, and ClinicalTrials.gov were searched. We identified original research studies with 1-year post-transplant survival data involving >5 DCD transplants. We performed meta-analyses examining 1-year survival, primary graft dysfunction, and acute rejection after LTx.

RESULTS

We identified 519 citations; 11 observational cohort studies met our inclusion criteria for systematic review, and 6 met our inclusion criteria for meta-analysis. There were no differences found in 1-year mortality after LTx between DCD and DBD cohorts in individual studies or in the meta-analysis (DCD [n = 271] vs DBD [n = 2,369], relative risk [RR] 0.88, 95% confidence interval [CI] 0.59-1.31, p = 0.52, I(2) = 0%). There was also no difference between DCD and DBD in a pooled analysis of 5 studies reporting on primary graft dysfunction (RR 1.09, 95% CI 0.68-1.73, p = 0.7, I(2) = 0%) and 4 studies reporting on acute rejection (RR 0.72, 95% CI 0.49-1.05, p = 0.09, I(2) = 0%).

CONCLUSIONS

Survival after LTx from DCD is comparable to survival after LTx from DBD in observational cohort studies. DCD appears to be a safe and effective method to expand the donor pool.

The Physiology of Brain Death and Organ Donor Management

Brain death is associated with complex physiologic changes that may impact the management of the potential organ donor. Medical management is critical to actualizing the individual or family’s intent to donate and maximizing the benefit of that intent. This interval of care in the PICU begins with brain death and consent to donation and culminates with surgical organ procurement. During this phase, risks for hemodynamic instability and compromise of end organ function are high. The brain dead organ donor is in a distinct and challenging pathophysiologic condition that culminates in multifactorial shock. The potential benefits of aggressive medical management of the organ donor may include increased number of donors providing transplantable organs and increased number of organs transplanted per donor. This may improve graft function, graft survival, and patient survival in those transplanted. In this chapter, pathophysiologic changes occurring after brain death are reviewed. General and organ specific donor management strategies and logistic considerations are discussed. There is a significant opportunity for enhancing donor multi-organ function and improving organ utilization with appropriate PICU management.

Donation after cardiac death in non-survivable burns

Major burns have previously been considered a contraindication to solid organ donation. We present two cases of successful organ donation and transplantation, after Maastricht category III cardiac death in adult patients with non-survivable burns injury. The implications of the outcome of these cases are that major burns should not be considered a contraindication to organ donation, and that cardiac death provides opportunity for patients with non-survivable burns to contribute to the pool of potential organ donors.

CYP3A5 polymorphism effect on cyclosporine pharmacokinetics in living donor renal transplant recipients: analysis by population pharmacokinetics

BACKGROUND

Cyclosporine is often used to prevent allograft rejection in renal transplant recipients. However, cyclosporine has a narrow therapeutic window and large variability in its pharmacokinetics. Individual characteristics and genetic polymorphisms can cause the variation. Hence, it is important to determine the cause(s) of the variation in cyclosporine pharmacokinetics. To our knowledge, this is the first reported population pharmacokinetic study of cyclosporine in living donor renal transplant recipients that considered the genetic polymorphism as a covariate.

OBJECTIVE

To build a population pharmacokinetic model of cyclosporine in living donor renal transplant recipients and identify covariates including CYP3A5*3, ABCB1 genetic polymorphisms that affect cyclosporine pharmacokinetic parameters.

METHODS

Clinical characteristics and cyclosporine concentration data for 69 patients who received cyclosporine-based immunosuppressive therapy after living donor renal transplantation were collected retrospectively for up to 400 postoperative days. CYP3A5*1/*3 and ABCB1C1236T, G2677T/A, C3435T geno-typing was performed. A population pharmacokinetic analysis was conducted using a NONMEM program. After building the final model, 1000 bootstrappings were performed to validate the final model.

RESULTS

In total, 2034 blood samples were collected. A 1-compartment open model with first-order absorption and elimination was chosen to describe the pharmacokinetics of cyclosporine. A population pharmacokinetic analysis showed that postoperative days, sex, and CYP3A5 genotype significantly affected the pharmacokinetics of cyclosporine. The final estimate of mean clearance was 56 L/h, and the mean volume of distribution was 4650 L. The interindividual variability for these parameters was 22.98% and 51.48%, respectively.

CONCLUSIONS

Using the present model to calculate the dose of cyclosporine with CYP3A5 genotyping can be possible for the patients whose cyclosporine concentration is not within the therapeutic range even with therapeutic drug monitoring.

Donor brain death inhibits tolerance induction in miniature swine recipients of fully MHC-disparate pulmonary allografts

We have previously shown that a short course of high-dose tacrolimus induces long-term tolerance to fully mismatched lung allografts procured from healthy MHC-inbred miniature swine. Here, we investigate whether donor brain death affects tolerance induction. Four recipient swine were transplanted with fully mismatched lung grafts from donors that were rendered brain dead and mechanically ventilated for 4 h before procurement (Group 1). These recipients were compared to two control groups (Group 2: 4 h of donor ventilation without brain death [n = 5]; and Group 3: no donor brain death with <1 h of ventilation [n = 6]). All recipients were treated with a 12-day course of tacrolimus. In contrast to both groups of control animals, the swine transplanted with lung allografts from brain dead donors all rejected their grafts by postoperative day 45 and showed persistent responsiveness to donor antigen by MLR. Several additional swine underwent brain death induction and/or mechanical ventilation alone to determine the effects of these procedures on the expression of proinflammatory molecules. Significant increases in serum concentrations of IL-1, TNF-α and IL-10 were seen after brain death. Upregulation of IL-1 and IL-6 gene expression was also observed.

Lung transplantation with donation after cardiac death donors: long-term follow-up in a single center

OBJECTIVE

We sought to examine long-term outcomes at the University of Wisconsin for all lung transplant recipients who received lungs from donation after cardiac death donors since the initiation of this program in 1993.

METHODS

Eighteen (4.2%) of the 424 lung transplantations performed in 406 patients between January 1993 and April 2009 used lungs from donation after cardiac death donors. Outcomes for this recipient cohort were compared with those for recipients who received organs from brain-dead donors.

RESULTS

Warm ischemic time (from withdrawal of support to reperfusion of organs) was 30 +/- 17 minutes (11-93 minutes). The patient survival rates in the donation after cardiac death group (DCD group) at 1, 3, and 5 years were 88.1% +/- 7.9%, 81.9% +/- 9.5%, and 81.9% +/- 9.5%, respectively. These survival rates were not different from those of the brain-dead donor group (BDD group, P = .66). The incidence of primary graft dysfunction in the DCD group was similar to that of the BDD group (P = .59). However, the incidence of airway complications was somewhat higher in the DCD group. Freedom from bronchiolitis obliterans syndrome at 1, 3, and 5 years in the DCD group was 80.4% +/- 10.2%, 80.4% +/- 10.2%, and 72.3% +/- 11.9%, respectively, and did not differ from the incidence of bronchiolitis obliterans syndrome in the BDD group (P = .59).

CONCLUSIONS

Our data show that the long-term patient and graft survival rates after donation after cardiac death lung transplantation were equivalent to those after brain-dead donor lung transplantation. Our findings suggest that the use of donation after cardiac death donors can safely and substantially expand the donor pool for lung transplantation.

Acute Rejection Features in Dual Kidney Transplant Recipients from Elderly Donors: Comparison of Calcineurin Inhibitor-Based and Calcineurin Inhibitor-Free Immunosuppressive Protocols

Features of acute rejection in dual kidney transplant have not been studied. The aim of this study is to compare acute rejections in dual kidney transplant recipients from elderly donors on different immunosuppressive protocols. Sixty-nine patients were evaluated: 28 received calcineurin inhibitor-based (group 1) and 41 received calcineurin inhibitor-free immunosuppression (group 2). Histology of all donor kidneys was evaluated before implantation. All rejections showed tubulitis in both groups, and were classified as T cell-mediated acute rejections. Incidence and Banff grade of rejections in the two groups were not significantly different. Late rejections however, were observed in group 1 ( P < 0.01) whereas steroid-resistant rejections occurred in group 2 ( P < 0.03). C4d deposition was only observed in group 2. Occurrence of acute rejection was significantly associated with graft loss due to interstitial fibrosis/tubular atrophy in both groups. In group 1 mean serum creatinine levels of patients with rejections at six months and one year were higher than those of patients without rejections ( P < 0.03 and P < 0.009, respectively). In group 2 they were higher at six months ( P < 0.01) but not at one year. In addition, graft loss due to interstitial fibrosis/tubular atrophy occurred in 3/28 patients in group 1 (10.7%, OR= 1.95, 95%CI 1.02–3.71), and in 1/41 patients in group 2 (2.4%, OR= 0.41, 95%CI 0.07–2.24). Taken together these results suggest better renal function in patients on calcineurin inhibitor-free immunosuppression. In conclusion, acute rejections were detrimental irrespective of the type of immunosuppression, but different features were observed with each therapy. A tailored approach should be advantageous for prevention and treatment of acute rejections.

Impact of innate and adaptive immunity on rejection and tolerance

Until recently, research on transplantation rejection and tolerance has been directed toward deciphering the mechanisms of the adaptive immune system. However, the emergence that the innate immune system, the body's first-line defense against pathogens, has a strong influence on adaptive immunity has galvanized interest in elucidating the interplay between these two arms of the immune system. The discovery of Toll-like receptors and the characterization of the cellular mediators involved in innate immunity have provided growing evidence that innate immunity affects the adaptive immune response. Emerging evidence has also shown that early "danger signals"' associated with ischemia-reperfusion injury or brain death contribute to innate immune activation, promoting rejection, and inhibiting tolerance induction. In addition, nonspecific stimuli such as increased donor age or patient disease may also serve to exert a synergistic influence on innate immune activation. Ultimately, controlling the events in innate immune activation may help drive tolerance induction and reduce the rate of rejection.