DAMP-Induced Allograft and Tumor Rejection: The Circle Is Closing.

The pathophysiological importance of the immunogenicity of damage-associated molecular patterns (DAMPs) has been pinpointed by their identification as triggers of allograft rejection following release from dying cells, such as after ischemia-reperfusion injury. In cancers, however, this strong trigger of a specific immune response gives rise to the success of cancer immunotherapy. Here, we review the recently literature on the pathophysiological importance of DAMP release and discuss the implications of these processes for allograft rejection and cancer immunotherapy, revealing a striking mechanistic overlap. We conclude that these two fields share a common mechanistic basis of regulated necrosis and inflammation, the molecular characterization of which may be helpful for both oncologists and the transplant community.

Transplantation and Damage-Associated Molecular Patterns (DAMPs).

Upon solid organ transplantation and during cancer immunotherapy, cellular stress responses result in the release of damage-associated molecular patterns (DAMPs). The various cellular stresses have been characterized in detail over the last decades, but a unifying classification based on clinically important aspects is lacking. Here, we provide an in-depth review of the most recent literature along with a unifying concept of the danger/injury model, suggest a classification of DAMPs, and review the recently elaborated mechanisms that result in the emission of such factors. We further point out the differences in DAMP responses including the release following a heat shock pattern, endoplasmic reticulum stress, DNA damage-mediated DAMP release, and discuss the diverse pathways of regulated necrosis in this respect. The understanding of various forms of DAMPs and the consequences of their different release patterns are prerequisite to associate serum markers of cellular stresses with clinical outcomes.

Calcineurin inhibitor-free immunosuppressive strategy in elderly recipients of renal allografts from deceased donors: 1-year results from a prospective single center trial.

Recently published data from our center have demonstrated the feasibility of a nephrotoxicity- and atherogenicity-free, mycophenolate mofetil (MMF)-based immunosuppressive protocol for elderly recipients of kidneys from elderly cadaveric donors. We investigated a therapeutic regimen of strictly monitored MMF (target mycophenolic acid [MPA] trough levels between 2-6 microg/mL) and steroids combined with a polyclonal-monoclonal induction regimen consisting of a low-dose, single shot of rabbit ATG (ATG-Fresenius) and the interleukin-2 receptor (IL-2R)-antibody basiliximab (d0 and d4). Between 1997 and 2007, we treated 175 elderly patients with an MMF-based, calcinearin inhibitor (CNI)-free immunosuppressive protocol. For the present cohort, 30 elderly recipients (67.8 +/- 3.8 years) of renal transplants from deceased donors (69.4 +/- 13.3 years) were recruited consecutively for this 5-year prospective, open, single center, pilot trial. One-year results of this clinical trial were patient and renal allograft survivals of 87% and 83%, respectively; death-censored 1-year graft survival was 97%. Mostly steroid-sensitive rejection episodes were observed in 46% of patients, with only 3 patients requiring serum antibody therapy. Renal allograft function was satisfactory, as reflected by a mean serum creatinine of 1.78 +/- 0.45 mg/dL and a Nankivell glomerular filtration rate (GFR) of 48.8 +/- 13.9 mg/dL at 6 months. Twenty-three percent of all patients demonstrated cytomegalovirus (CMV) infections; however, only 3.3% developed CMV disease. Application of a combined polyclonal-monoclonal induction regimen using a nephrotoxicity- and atherogenicity-free, MMF-based immunosuppressive maintenance protocol in elderly cadaveric kidney transplant recipients led to acceptable short-term outcomes, albeit at the expense of an increased rejection rate, comparable to that previously published for elderly (>50 years) recipients of allografts from elderly (>50 years) cadaveric donors.

The history of the EuroSPK - Study Group.

The EuroSPK Study group was created during the 4th Spitzingsee 1997 workshop in Kühtai, Austria. Thanks to W. Land for the incentive to gather European Centres--with Switzerland and Israel--and propose them to joint efforts and share data in the field of pancreas transplantation. Today, two prospective randomized studies have been already performed; a lot of data and results have been generated and worldwide spread. The spirit of the group will continue with a new interest in innate immunity and prevention of the ischemic reperfusion injury in pancreas transplantation.

Emerging science, emerging ethical issues: who should fund innate alloimmunity-suppressing drugs?

An emerging body of evidence suggests that the innate immune system plays a critical role in allograft rejection. Any injury to the donor organ, e.g. the reperfusion injury, induces an inflammatory milieu in the allograft which appears to be the initial event for activation of the innate immune system. Injury-induced intragraft damage- associated molecular patterns (DAMPs) are recognized by donor-derived and recipient-derived, TLR4/2-bearing immature dendritic cells (iDCs). After recognition, these cells mature and initiate allorecognition/alloactivation in the lymphoid system of the recipient. Indeed, the key "innate" event, leading to activation of the adaptive alloimmune response, is the injury-induced, TLR4-triggered, and NFkappaB-mediated maturation of DCs ("innate alloimmunity"). Time-restricted treatment of innate immune events would include 1) treatment of the donor during organ removal, 2) in-situ/ex-vivo treatment of the donor organs alone, and 3) treatment of the recipient during allograft reperfusion and immediately postoperatively. Treatment modalities would include 1) minimization of the oxidative allograft injury with the use of antioxidants; 2) prevention of the TLR4-triggered maturation of DCs with the use of TLR4-antagonists; 3) inhibition of complement activation with the use of complement inhibiting agents. According to data from clinical and experimental studies it can be assumed that successful suppression of innate alloimmune events results in either subsequent significant reduction in, or even complete avoidance of the currently applied adaptive alloimmunity-suppressing drugs. However, in view of the time-restricted period of treatment, and the fear to potentially destroy its own business with currently applied alloimmunity-suppressing drugs, the pharmaceutical industry is still, but quite legitimately, reluctant to invest in the high cost of clinical development of those drugs for transplant patients because there are no marketing interests. On the other hand, clinical development of innate alloimmunity-suppressing drugs is urgently warranted. But: Who should fund? In this article, three options are explored which may contribute to a solution of the problem: 1) provision of incentives to companies for drug development; 2) conduction of clinical trials in developing countries; and 3) creation of a public-private professional partnership in analogy to the "European Rare Diseases Therapeutic Initiative" (ERDITI). We suggest and recommend the creation of such a partnership which may be called: "The European Initiative for the Suppression of Innate Alloimmunity" ("EISIA"). In analogy to ERDITI, the main goals of this organization should be:--to provide a streamlined facilitated process of collaboration between Academic Teams/Transplant Centres, Study Groups, and Pharma Companies to develop innate alloimmunity-suppressing drugs;--to give Academic Teams/Transplant Centres facilitated access to a large variety of compounds, developed by companies for other indications, which can be evaluated pre-clinically and, if warranted, clinically;--to guarantee the continuity all the way from research to development and commercialisation of the drug. If preclinical studies uncover the potential of a compound for suppressing innate alloimmune events, the Pharma Partner who has rights to this compound will either develop himself the drug for organ transplantation indication or allow its development by the academic team or a third party if he has no intentions of developing himself.

Immunosuppression in pancreas transplantation: the Euro SPK trials and beyond.

The Immunosuppression in Pancreas Transplantation was historically based on the fact that the pancreas is an extremely immunogenic organ. Quadruple drug therapy with polyclonal or monoclonal antibodies induction was the mainstay therapy since the introduction of Cyclosporine A. In the modern era of Immunosuppression, Mycophenolate Mofetil replaced Azathioprine while Tacrolimus-another potent calcineurin inhibitor-had-and still has-a difficult challenge to replaced Cyclosporine A, due to its potential diabetogenic effect. Thanks to the first two EuroSPK studies which prospectively tried to answer several questions in that field. But, the future challenge will be in understanding the impact of innate immunity and ischemic reperfusion injuries on the long-term graft function. Hopefully, new drugs will be available and tested to block unspecific deleterious reactions to attenuate the proinflammatory response. It will be the aim of the third Euro SPK Study.

Innate immunity-mediated allograft rejection and strategies to prevent it.

Experimental and clinical evidence has accumulated in support of the notion that oxidative injuries to allografts induce an adaptive alloimmune response which leads to acute rejection. The link between the initial injury and subsequent rejection is the innate immune system represented by injury-activated donor-derived and recipient-derived dendritic cells which interact with naïve T cells of the recipient to induce an alloimmune T-cell response. Therefore, time is mature to consider potential therapeutic strategies that are able to suppress events of innate immunity. Such strategies refer to a "time-restricted therapeutic window" that includes treatment of the donor during organ removal and the recipient during allograft reperfusion. Major targets of such treatment include (1) mitigation of the oxidative allograft injury; (2) inhibition of injury-induced activation of complement; (3) inhibition of Toll-like receptor (TLR)-mediated and innate lymphocyte-triggered maturation of dendritic cells; and (4) blockade of innate effector functions. A considerable variety of promising experimental studies about the prevention/inhibition of innate immune events has already been performed, including the successful experimental use of gene silencing methods, eg, using RNA interference technology with the application of small interfering RNA (siRNA). In addition, a few clinical trials with antioxidants (edaravone, SOD-mimetics), complement inhibitors (pexelizumab, TP-10) in patients with acute myocardial infarction, and TLR4 antagonists (TAK-242, E-5564) in patients with sepsis have been performed or are underway. Performance of similar clinical trials in transplant patients with antioxidative drugs, complement inhibitors, and/or TLR4 antagonists is urgently warranted; siRNAs appear to be extremely attractive for investigation in experimental allogeneic transplant models.

Simultaneous pancreas-kidney transplantation: analysis of rejection.

UNLABELLED: The 3-year data concerning the occurrence of rejection episodes (RE) are reported herein. PATIENTS AND METHODS: Two hundred five simultaneous pancreas-kidney (SPK) transplantations were performed from May 1998 to September 2000, including 103 patients randomly assigned to tacrolimus (Tac) and 102 to cyclosporine microemulsion (CsA-ME). All patients received concomitant rATG induction therapy, mycophenolate mofetil (MMF), and short-term corticosteroids. RESULTS: After a follow-up of 3 years, acute rejection episodes occurred in 41 patients receiving tacrolimus and in 51 patients receiving CsA ME. The majority of first rejection episodes in both groups occurred during the first 6 months (93% and 90%, respectively) and in most cases were treated with corticosteroids (88% and 90%). Actuarial rejection-free graft survival was not significantly different between the two groups (54% and 44% at 3 years posttransplant). In a multivariate analysis, HLA compatibility (P = .003) and graft vessel extension (P = .0005) had a significant influence on rejection-free survival. Rejection influenced pancreatic graft survival (P = .01) and pancreatic graft loss owing to rejection influenced patient survival (P = .02). In the intent-to-treat analysis of early rejection, first moderate-to-severe episodes (1 of 40 versus 12 of 47; P = .004) and refractory episodes (2 of 40 versus 10 of 47; P = .03) were significantly lower with tacrolimus than with CsA ME. Pancreatic graft survival was worse among late rejectors (53%) than nonrejectors (86%; P = .002). In addition, serum creatinine was highest in late rejectors. In conclusion, Tac-based immunosuppressive therapy shows advantages over CsA ME in terms of the severity of acute rejection episodes among patients undergoing SPK transplantation.

Cyclosporine: 20 years of experience at the University of Munich.

The history of solid organ transplantation is, from an immunotherapeutic standpoint, divided in the era before and after the introduction of cyclosporine to the clinic. The introduction of cyclosporine to the clinic in 1978 is looked upon as a turning point in transplantation. The immediate success of the new drug was based on the reduction of early graft rejection and the substantial improvement of 1-year graft survival. With growing experience in the use of this new compound, together with the ability to measure drug levels in serum, allograft rejection and organ survival could be improved even further. Because of the clinical results, cyclosporine became the gold standard in immunosuppressive therapy after organ transplantation. Even after 20 years, as more and more new immunosuppressants emerge, the clinical evaluation of a new drug is frequently compared versus a cyclosporine-based regimen. Today, cyclosporine is probably one of the best investigated drugs in the field of organ transplantation. Beside the undoubted benefits of cyclosporine, experimental and clinical studies have also revealed some unwanted effects, such as nephrotoxicity and an increased risk in development of malignant tumors. Here, we review the experience at our institution with transplant recipients receiving cyclosporine as the main immunosuppressant over the past 20 years.

Contrast-enhanced MR angiography in patients after kidney transplantation.

The aim of this study was to investigate the value of a contrast-enhanced 3D MR angiography in detecting postoperative vascular complications after kidney transplantation in comparison with digital subtraction angiography (DSA). Forty-one patients who underwent a kidney transplantation were examined with MR angiography and DSA. Contrast-enhanced MR angiography was performed as a dynamic measurement with one precontrast and three postcontrast measurements. Maximum intensity projection reconstructions were performed for all postcontrast data sets after DSA. The results were evaluated by two independent observers who were unaware of the DSA results. Twenty-three hemodynamically significant arterial stenoses were identified with DSA in the iliac arteries ( n=7), the renal allograft arteries ( n=12), and in their first branches ( n=4). For a patient-based analysis the sensitivity and specificity, respectively, for observer 1 were 100 and 97%, and for observer 2, 100 and 93%. Respective data were 100 and 100% after a consensus evaluation by two observers. Complications involving the renal veins were detected in 2 cases and perfusion defects of the kidney parenchyma were detected in 4 cases. Contrast-enhanced MR angiography is a reliable method in identifying postoperative arterial stenoses after kidney transplantation. In addition, dynamic MR angiography can be helpful in detecting venous complications and perfusion defects in kidney allografts.

Increased rate of renal transplant failure in patients with the G20210A mutation of the prothrombin gene.

In patients with thrombophilia caused by reduced physiological anticoagulation, renal transplant failure occurs more frequently. Previous studies showed the importance of the protein C system, a physiological anticoagulatory pathway that inhibits thrombus formation. However, excess activation of the hemostatic system also may result in thrombosis. The G20210A mutation in the prothrombin gene is such a prothrombotic risk factor that results in increased thrombus formation because of elevated factor II levels in plasma. We analyzed graft function in 270 consecutive patients who received 311 renal transplants. The presence of a normal or mutated prothrombin allele was determined by polymerase chain reaction amplification and restriction fragment length polymorphism analysis of genomic DNA. Demographic data were extracted from hospital records. Graft survival was calculated for patients with and without the G20210A mutation. We identified 9 patients heterozygous for the G20210A mutation in the prothrombin gene who had received a total of 12 renal transplants. Of these 12 transplants, 2 grafts were lost within the first year. Median graft survival for patients heterozygous for the 20210A allele was 65.9 months (range, 0 to 101 months) compared with 149 months (range, 0 to 237 months) for patients homozygous for the normal 20210 G allele (P = 0.02). The G20210A mutation represented a 2.95-fold (95% confidence interval, 1.03 to 8.46) increase in risk for graft loss. Only 1 patient with this mutation achieved graft function exceeding 101 months. The G20210A mutation of the prothrombin gene is an independent risk factor for graft failure.

Dose optimization of mycophenolate mofetil when administered with a low dose of tacrolimus in cadaveric renal transplant recipients.

BACKGROUND: Supplementation of immunosuppressive therapy with mycophenolate mofetil (MMF) has been found to reduce the rate of acute rejection in renal transplantation. We report a dose-finding study for MMF when administered in combination with low-dose tacrolimus and corticosteroid prophylaxis in cadaveric renal transplant recipients. METHODS: Two hundred thirty-two patients at 16 centers were enrolled in this randomized, parallel-group study. The three treatment groups were tacrolimus and corticosteroids (MMF-0 group, n=82); tacrolimus, corticosteroids, and 1 g of MMF daily (MMF-1 g group, n=79); and tacrolimus, corticosteroids, and 2 g of MMF daily (MMF-2 g group, n=71). Study duration was 6 months, and patients were followed up for patient and graft survival for 12 months. RESULTS: At 6 months posttransplantation, daily doses of 1 g and 2 g of MMF were associated with significantly lower rates of acute rejection compared with tacrolimus alone. The Kaplan-Meier rates were 48.5%, 24.9%, and 22.9%, respectively, for the three treatment groups when acute rejection was determined by clinical criteria (P=0.007). At month 12, patient survival rates were 100%, 97.5%, and 97.2% and graft survival rates were 90.2%, 92.4%, and 93.0% for the MMF-0 group, MMF-1 g group, and the MMF-2 g group, respectively. Gastrointestinal adverse events and leukopenia were higher in the MMF groups, especially in the MMF-2 g group (P<0.05). CONCLUSIONS: Low-dose tacrolimus combined with a MMF dose of 1 g daily and corticosteroids provided an optimized efficacy and safety profile. A higher dose of MMF (2 g) was associated with greater toxicity without a significant improvement in efficacy.

CC chemokine receptor 5 and renal-transplant survival.

BACKGROUND: About 1% of white populations are homozygous carriers of an allele of the gene for the CC chemokine receptor 5 (CCR5) with a 32 bp deletion (CCR5Delta32), which leads to an inactive receptor. During acute and chronic transplant rejection, ligands for CCR5 are upregulated, and the graft is infiltrated by CCR5-positive mononuclear cells. We therefore investigated the influence of CCR5Delta32 on renal-transplant survival. METHODS: Genomic DNA from peripheral-blood leucocytes of 1227 renal-transplant recipients was screened by PCR for the presence of CCR5Delta32. Demographic and clinical data were extracted from hospital records. Complete follow-up data were available for 576 recipients of first renal transplants. Graft survival was analysed by Fisher's exact test and Kaplan-Meier plots compared with a log-rank test. FINDINGS: PCR identified 21 patients homozygous for CCR5Delta32 (frequency 1.7%). One patient died with a functioning graft. Only one of the remaining patients lost transplant function during follow-up (median 7.2 years) compared with 78 of the 555 patients with a homozygous wild-type or heterozygous CCR5Delta32 genotype. Graft survival was significantly longer in the homozygous CCR5Delta32 group than in the control group (log-rank p=0.033; hazard ratio 0.367 [95% CI 0.157-0.859]). INTERPRETATION: Patients homozygous for CCR5Delta32 show longer survival of renal transplants than those with other genotypes, suggesting a pathophysiological role for CCR5 in transplant loss. This receptor may be a useful target for the prevention of transplant loss.