Immunosuppression in pancreas transplantation: progress, problems and perspective

Membranes to achieve immunoprotection of transplanted islets

Transplantation of islet or beta cells is seen as the cure for type 1 diabetes since it allows physiological regulation of blood glucose levels without requiring any compliance from the patients. In order to circumvent the use of immunosuppressive drugs (and their side effects), semipermeable membranes have been developed to encapsulate and immunoprotect transplanted cells. This review presents the historical developments of immunoisolation and provides an update on the current research in this field. A particular emphasis is laid on the fabrication, characterization and performance of membranes developed for immunoisolation applications.

Mesenchymal stem cells prevent acute rejection and prolong graft function in pancreatic islet transplantation

BACKGROUND

Pancreatic islet transplantation is a promising cell-based therapy for type 1 diabetes (insulin-dependent diabetes mellitus), a disease triggered by the immune response against autoantigens of beta-cells. However, the recurrence of immune response after transplantation and the diabetogenic and growth-stunting side effects of immunosuppressants are major challenges to the application of islet transplantation. Mesenchymal stem cells (MSCs) have recently been reported to modulate the immune response in allogeneic transplantation.

METHODS

The ability of MSCs, either syngeneic or allogeneic to recipients, to prevent acute rejection and improve glycemic control was investigated in rats with diabetes given a marginal mass of pancreatic islets through the portal vein.

RESULTS

Reduced glucose levels and low-grade rejections were observed up to 15 days after transplantation upon triple-dose administration of MSCs, indicating that MSCs prolong graft function by preventing acute rejection. The efficacy of MSCs was associated with a reduction of pro-inflammatory cytokines and was independent of the administration route. Efficacy was similar for MSCs whether syngeneic or allogeneic to recipients and comparable to that of immunosuppressive therapy.

CONCLUSIONS

The results show that MSCs modulate the immune response through a down-regulation of pro-inflammatory cytokines, suggesting that MSCs may prevent acute rejection and improve graft function in portal vein pancreatic islet transplantation.

Successful Pancreas–Renal Transplantation Without Induction Therapy

Most pancreas transplant centers initially use immunosuppression with antilymphocyte induction because the pancreas appears to be a highly immunogeneic organ. Although the addition of an antilymphocyte agent provides enhanced immunosuppression in the early posttransplant period, it is associated with added costs and adverse reactions. In this study we evaluated the safety and efficacy of tacrolimus (Tac), mycophenolate mofetil (MMF), and steroid immunosuppression without induction after simultaneous kidney-pancreas transplantation (SKPT). Six patients (30%) displayed rejection episodes with a mean follow-up of 12 months (range = 4 to 18 months). No graft was lost due to rejection. The results of this series suggest that SKPT can be safely performed without induction therapy.

Long-term outcome of sirolimus rescue in kidney-pancreas transplantation

Sirolimus (SRL) rescue in kidney-pancreas transplantation has not been well described. We reviewed 112 KPTxs performed at our institution between December 3, 1995 and June 27, 2002. All patients received antibody induction, tacrolimus (TAC), mycophenolate mofetil (MMF), and steroids. In 35 patients, SRL was substituted for MMF for the following reasons: acute rejection (AR) of kidney or pancreas despite adequate TAC levels, MMF intolerance, increasing creatinine levels, and TAC-induced hyperglycemia. Three-year kidney and pancreas graft survivals were 97% and 90%, respectively. Of 10 patients who were switched to SRL because of AR, one kidney failed because of antibody-resistant AR, and one kidney developed borderline AR; the other eight patients remain AR-free. AR developed in seven other patients despite therapeutic SRL levels; six had TAC levels less than 4.5 ng/mL. The mean creatinine levels overall and for the group with increasing creatinine remained stable. All patients who were switched to SRL for TAC-induced hyperglycemia or MMF intolerance improved. Kidney-pancreas transplant recipients can be safely switched to SRL with excellent graft and patient survival.

Long-Term outcome of sirolimus rescue in Kidney–Pancreas transplantation

The aim of this study was to evaluate long-term outcome of sirolimus (SRL) rescue in kidney-pancreas transplantation (KPTx). We reviewed 112 KPTx performed at our institution from 12/3/95 to 6/27/02. All patients received antibody (Ab) induction, tacrolimus (TAC), mycophenolate mofetil (MMF), and steroids. Thirty-five patients (31%) had SRL substituted for MMF for the following indications: (1) acute rejection (AR) of kidney or pancreas despite adequate TAC levels; (2) intolerance of full-dose MMF; (3) rising creatinine; and (4) TAC-induced hyperglycemia. Target SRL and TAC levels were 10 ng/mL and 5 ng/mL, respectively. Mean follow-up was 3 +/- 2 years overall and 1.2 +/- 0.5 years after SRL rescue. No patients died. One- and 3-year actuarial kidney and pancreas graft survival was 97%, 97%, and 95%, 90%, respectively. Of 10 patients switched to SRL for AR, 1 kidney failed from Ab-resistant AR, 1 kidney developed borderline AR, and the other 8 remain AR-free. Seven other patients developed AR despite therapeutic SRL levels; of these, 6 (86%) had mean TAC levels of <4.5 in the month preceding AR. Mean creatinine overall and for the rising creatinine group remained stable. All patients switched to SRL for TAC-induced hyperglycemia or MMF intolerance demonstrated biochemical or clinical improvement. Sirolimus-related infection or other serious adverse events (SAE) were uncommon. In conclusion, KPTx recipients can be safely switched to SRL with long-term stabilization of renal function, excellent graft and patient survival, and no increase in SAE. A minimum TAC level of 4.5 ng/mL may be necessary to prevent late AR.

Mycophenolate mofetil in solid-organ transplantation

This review focuses on the use of mycophenolate mofetil (MMF) as an immunosuppressive agent in solid-organ transplantation. MMF, a non-competitive inhibitor of inosine monophosphate dehydrogenase, blocks de novo purine synthesis in T and B lymphocytes, resulting in the selective inhibition of proliferation of these cells in response to antigenic stimuli. MMF may also promote apoptosis of these cells. The immunosuppressive ability of MMF is thought to derive mainly from the inhibition of inosine monophosphate dehydrogenase. The other effects of MMF include suppression of antibody synthesis by B lymphocytes, inhibition of proliferation of smooth muscle cells in culture and impaired glycosylation of adhesion molecules. MMF may exhibit anti-inflammatory effects resulting from decreased activity of the inducible form of nitric oxide synthase, a consequence of depletion of tetrahydrobiopterin, which leads to decreased generation of peroxynitrite, a pro-inflammatory molecule. The pharmacokinetics, pharmacodynamics and principles underlying therapeutic drug monitoring of MMF are reviewed. The results of the pivotal clinical trials of MMF in kidney and heart transplantation are discussed and a summary of the major studies demonstrating a positive effect of MMF on renal transplantation outcomes is presented. The use of MMF in the context of ABO-incompatible renal transplantation, renal transplantation in highly sensitised and cross-match positive recipients, humoral rejection of renal allografts, chronic allograft nephropathy and steroid/calcineurin inhibitor minimisation in renal transplantation are also discussed.

Two-dose daclizumab regimen in simultaneous kidney-pancreas transplant recipients: primary endpoint analysis of a multicenter, randomized study

BACKGROUND

Controversy exists about the optimal immunosuppressive regimen in simultaneous kidney-pancreas transplant (SKPT) recipients. This study determined the safety and efficacy of two dosing regimens of daclizumab compared with no antibody induction in SKPT recipients receiving tacrolimus, mycophenolate mofetil, and steroids.

METHODS

A total of 297 SKPT patients were enrolled in this prospective, multicenter, randomized, open-label study. The patients were randomized into three groups: daclizumab 1 mg/kg per dose every 14 days for five doses (group I, n=107), daclizumab 2 mg/kg per dose every 14 days for two doses (group II, n=112), and no antibody induction (group III, n=78). All patients received tacrolimus, mycophenolate mofetil, and steroids as maintenance immunosuppression.

RESULTS

Demographic and transplant characteristics were similar among the groups. At 6 months, there were no differences in patient, kidney, and pancreas graft survival rates among the three groups. The probability of either kidney or pancreas allograft rejection at 6 months was 21%, 17%, and 32% in groups I, II, and III, respectively (P=0.042). The median time to first acute rejection of either the kidney or pancreas was 23 days in group I, 44 days in group II, and 20 days in group III (group I vs. II, P=0.078; group II vs. III, P=0.016). At 6 months, the actuarial event-free survival (no acute rejection, allograft loss, or death) rates were 66%, 77%, and 56% in groups I, II, and III, respectively (group I vs. III, P=0.119; group II vs. III, P=0.002). There were no differences in the incidence of serious adverse events including infectious complications among the groups. All three groups demonstrate excellent kidney and pancreas function at 6 months.

CONCLUSIONS

Daclizumab is safe and effective in reducing the incidence of acute rejection in SKPT recipients compared with no antibody induction. Moreover, the two-dose regimen of daclizumab (2 mg/kg on days 0 and 14) compares favorably with the standard five-dose regimen.

Impact of acute rejection episodes on long-term graft survival following simultaneous kidney-pancreas transplantation

Although it is well established that acute rejection is one of the major risk factors for chronic graft loss following kidney transplantation, its effect on long-term graft survival following simultaneous kidney-pancreas transplants (SKPTs) is less well known. We analyzed a large cohort of SKPTs and cadaver kidney transplants reported to the United Network for Organ Sharing database during 1988-97, to determine the impact of acute rejection episodes on long-term kidney and pancreas graft survival. Only patients whose kidney and pancreas grafts had survived for at least 1 year were included. Other potential risk factors influencing long-term graft survival were included in the analysis. Of the 4251 SKPTs, 45% had no acute rejection, 36% had kidney only rejection, 3% had pancreas only rejection, and 16% had both kidney and pancreas rejection within the 1st year post transplant. The 5-year kidney and pancreas graft survival rates adjusted for other risk factors were 91% and 85%, respectively; for those with no acute rejection episodes, 88% and 84%, respectively; for those with kidney only rejection, 94% and 83%, respectively; for those with pancreas only rejection; and 86% and 78%, respectively, for those with both kidney and pancreas rejection. The relative risk (RR) of kidney graft failure was 1.32 when acute rejection involved the kidney graft only, while the RR was 1.53 when the rejection involved both organs. We conclude that acute rejection episodes have a negative impact on the long-term kidney graft survival in the SKPT population similar to that in the cadaver kidney transplant population. Patients who had acute rejection episodes of both kidney and pancreas have the worst long-term graft survival.

Thymoglobulin for induction or rejection therapy in pancreas allograft recipients: a single centre experience

PURPOSE

To review the safety and efficacy of thymoglobulin in pancreas transplant patients receiving tacrolimus and mycophenolate mofetil.

METHODS

Retrospective, single centre analysis of 45 patients transplanted between 1995 and 2000 who received 54 courses of thymoglobulin, including 36 courses in 29 solitary pancreas transplant recipients (16 pancreas alone, 13 pancreas after kidney transplants) and 18 courses in 16 simultaneous kidney-pancreas transplant patients. Thirty-two patients (71%) were primary pancreas transplants, 10 (22%) were second transplants and three (7%) were third transplants. Of the 54 treatment courses, 19 (35%) were for induction, 27 (50%) were for primary rejection and eight (15%) were rescue therapy for rejection. All rejection episodes were biopsy-proven in at least one organ.

RESULTS

The median thymoglobulin dose was 1.5 mg/kg/d with a mean of six doses (range 3-10). Dose reduction or interruption was required in 28 courses (52%), most often due to leukopenia (n = 24), fever (n = 2) and thrombocytopenia (n = 2). Thymoglobulin was resumed in all but three patients, two with persistent fever and one with infection. Infectious complications (n = 25) occurred in 17 patients (38%) within 30 days and included bacterial (n = 16), cytomegalovirus (n = 4), polyoma (n = 1), fungal (Candida albicans, n = 1), toxoplasmosis (n = 1) and ehrlichiosis (n = 2). Post-transplant lymphoproliferative disease occurred in two patients (4%) at a mean of 70 d post-thymoglobulin treatment. In the 19 patients that received thymoglobulin induction, one simultaneous kidney-pancreas transplant, two pancreas alone and four pancreas after kidney transplant recipients developed rejection (37% incidence), while all remaining patients followed by surveillance protocol biopsies were rejection-free. In the 35 patients that received thymoglobulin for rejection, reversal occurred in 26 of the patients (74%). Rejection recurred within 30 d in five patients and post-treatment biopsies revealed persistent rejection in three of 20 pancreas and two of eight renal biopsies. After a mean follow-up of 6 months, the actual patient and pancreas graft survival rates were 93% and 71%, respectively.

CONCLUSION

Thymoglobulin was effective as induction therapy in high-risk pancreas transplant recipients, and resulted in initial reversal of rejection in 74% of patients. Dose adjustments were required in over half the cases and were usually due to leukopenia. Infections occurring subsequent to thymoglobulin were not uncommon and reflected the immunosuppressive burden of the patient population.

Mechanisms of clinically relevant drug interactions associated with tacrolimus

The clinical management of tacrolimus, a macrolide used as immunosuppressant after transplantation, is complicated by its narrow therapeutic index in combination with inter- and intraindividually variable pharmacokinetics. As a substrate of cytochrome P450 (CYP) 3A enzymes and P-glycoprotein, tacrolimus interacts with several other drugs used in transplantation medicine, which also are known CYP3A and/or P-glycoprotein inhibitors and/or inducers. In clinical studies, CYP3A/P-glycoprotein inhibitors and inducers primarily affect oral bioavailability of tacrolimus rather than its clearance, indicating a key role of intestinal P-glycoprotein and CYP3A. There is an almost complete overlap between the reported clinical drug interactions of tacrolimus and those of cyclosporin. However, in comparison with cyclosporin, only few controlled drug interaction studies have been carried out, but tacrolimus drug interactions have been extensively studied in vitro. These results are inconsistent and are of poor predictive value for clinical drug interactions because of false negative results. P-glycoprotein regulates distribution of tacrolimus through the blood-brain barrier into the brain as well as distribution into lymphocytes. Interaction of other drugs with P-glycoprotein may change tacrolimus tissue distribution and modify its toxicity and immunosuppressive activity. There is evidence that ethnic and gender differences exist for tacrolimus drug interactions. Therapeutic drug monitoring to guide dosage adjustments of tacrolimus is an efficient tool to manage drug interactions. In the near future, progress can be expected from studies evaluating potential pharmacokinetic interactions caused by herbal preparations and food components, the exact biochemical mechanism underlying tacrolimus toxicity, and the potential of inhibition of CYP3A and P-glycoprotein to improve oral bioavailability and to decrease intraindividual variability of tacrolimus pharmacokinetics.

A multicenter, open-label, comparative trial of two daclizumab dosing strategies vs. no antibody induction in combination with tacrolimus, mycophenolate mofetil, and steroids for the prevention of acute rejection in simultaneous kidney-pancreas transplant recipients: interim analysis

INTRODUCTION

The safety and efficacy of daclizumab (1 mg/kg/dose every 14 d for five doses) has been established in kidney and heart transplant recipients. Alternative dosing regimens based on pharmacokinetic simulation and limited clinical trials are being investigated. The purpose of this ongoing multicenter study is to determine the safety and efficacy of two dosing regimens of daclizumab as an adjunctive immunosuppressive agent compared with no antibody induction in simultaneous kidney-pancreas transplant (SKPT) recipients receiving tacrolimus (TAC), mycophenolate mofetil (MMF) and steroids as primary immunosuppression.

METHODS

This is an interim report of a multicenter, prospective, open-label, randomized study with a target enrolment of 290 patients. Eligible SKPT patients were randomized to one of three groups: daclizumab 1 mg/kg/dose every 14 d for five doses (Group I), daclizumab 2 mg/kg/dose every 14 d for two doses (Group II), and no antibody induction (Group III). The primary endpoint of the study is a composite of the incidence of presumed or biopsy-proven kidney or pancreas rejection, graft loss, or death within the first 6 months post-transplantation.

RESULTS

A total of 166 patients were randomized into the three groups [Group I (n = 70), Group II (n = 74), Group III (n = 22)]. Demographic and transplant characteristics were similar among the groups. At a minimum follow-up of 3 months, patient, kidney and pancreas graft survival rates were similar among the three groups. However, the rates of acute renal allograft rejection were 18% (Group I), 8% (Group II), and 36% (Group III), p < 0.05. The probabilities of either kidney or pancreas allograft rejection were 22% (Group I), 8% (Group II), and 38% (Group III). At 3 months, the actuarial event-free survival (no acute rejection, allograft loss, or death) rates were 67, 81 and 50% in Groups I, II, and III, respectively. There were no differences in the incidence of infectious complications among the groups and no serious adverse events associated with daclizumab were observed.

CONCLUSIONS

The two-dose regimen (Group II) appears to be as effective as the five-dose regimen (Group I) in preventing acute rejection after SKPT and is associated with the lowest acute rejection rates and the highest rate of event-free survival (no rejection or graft loss). However, the benefits of daclizumab compared with no antibody induction await larger sample size accrual.

Multicenter survey of daclizumab induction in simultaneous kidney-pancreas transplant recipients

We report an experience with 71 simultaneous kidney-pancreas transplant (SKPT) recipients receiving daclizumab induction in combination with tacrolimus (TAC), mycophenolate mofetil (MMF), and steroids. The mean follow-up time was 5.9+/-2.5 (SD) months (range 0.5-11 months). The study population included 47 males (65%) and 24 females (35%) with a mean age of 40+/-8 years. The mean pretransplant duration of diabetes and dialysis were 25+/-8 and 1.5+/-0.9 years (34 hemodialysis, 16 peritoneal dialysis), respectively. Mean HLA match was 1.2+/-1.5, with one patient receiving a second transplant. The mean cold ischemic times for the kidney and the pancreas were 15+/-5 and 16+/-4 hr, respectively. Six-month patient, kidney, and pancreas graft survival and rejection rates were 97, 96, 93, and 35%, respectively. There were two deaths, one due to fungal infection and the other due to a cardiac event. There were three kidney graft losses, two immunological, and one death with function. Of the five pancreas graft losses, two were due to infection, one immunological, one thrombosis, and one death with function. The patient population was then stratified according to the number of daclizumab doses: 4-5 doses (n=45) or 1-3 doses (n=26). There were no differences in patient and kidney graft survival rates, 98 vs. 96%, and 92 vs. 92%, respectively. However, there was a trend toward improved pancreas graft survival in the group receiving 4-5 doses (96%) compared with 1-3 doses (85%), P=0.07. Although more patients receiving 1-3 doses had rejection (54%) than patients receiving 4-5 doses (24%), there was no dose response relationship between the total number of doses or the adjusted total mg/kg dose and time to rejection. All patients with functioning grafts have good renal and pancreas allograft function at 6 and 12 months. The overall incidence of major infection was 27% and there were no differences in the incidence of infection between the two groups. No major adverse events were attributed to daclizumab use. In conclusion, excellent short-term outcomes were noted in this retrospective, multicenter survey of initial experience with daclizumab induction in combination with TAC, MMF, and steroids in SKPT recipients. Optimal dosing strategies for SKPT recipients remain to be determined.

Results of pancreas transplantation after steroid withdrawal under tacrolimus immunosuppression

PURPOSE

The results of steroid withdrawal in pancreas transplant recipients under tacrolimus immunosuppression were analyzed.

METHODS

From July 4, 1994 until April 30, 1998, 147 pancreas transplantations were performed in 141 patients, including 126 simultaneous pancreas-kidney transplantations, 13 pancreas after kidney transplantation, and 8 pancreas transplantations alone. Baseline immunosuppression consisted of tacrolimus and steroids without antilymphocyte induction. Twenty-three patients were excluded from analysis because of early graft loss in 17 cases, retransplantation in 5 cases, and simultaneous pancreas-kidney transplantation after heart transplantation in 1 patient.

RESULTS

With a mean follow-up of 2.8+/-1.1 years (range 1.0 to 4.8 years), complete steroid withdrawal was achieved in 58 (47%) patients with a mean time to steroid withdrawal of 15.2+/-8 months (range 4 to 40 months after transplantation). Of the entire cohort of 141 patients, overall 1-, 2-, and 4-year patient survival rates were 98%, 95.5%, and 86%, respectively. Overall 1-, 2-, and 4-year graft survival rates were 83%, 80%, and 71% (pancreas) and 95%, 91%, and 84% (kidney), respectively. Of the 124 patients analyzed for steroid withdrawal, 1-, 2-, and 4-year patient survival rates were 98%, 97%, and 92%, respectively. Overall 1-, 2-, and 4-year graft survival rates were 98%, 91.5%, 83% (pancreas) and 97%, 95%, and 91% (kidney). Patient, pancreas, and kidney survival rates at 1 year were 100%, 100%, and 98% (off steroids) versus 97%, 91%, and 96% (on steroids, all NS) and at 4 years were 100%, 94%, and 95% (off steroids) versus 78%, 68%, and 85% (on steroids, P = 0.01, 0.002, and NS, respectively). The cumulative risk of rejection at the time of follow-up was 76% for patients on steroids versus 74% for patients off steroids (P = NS). Seven patients originally tapered off steroids were treated for subsequent rejection episodes, which were all steroid sensitive, and two of these seven patients are currently off steroids. Thirteen patients received antilymphocyte therapy for steroid-resistant rejection, five of whom are now off steroids. Tacrolimus trough levels were 9.3+/-2.4 ng/ml (off steroids) and 9.7+/-4.3 (on steroids, P = NS). Mean fasting glucose levels were 98+/-34 mg/dl (off steroids) and 110+/-41 mg/dl (on steroids, P = NS). Mean glycosylated hemoglobin levels were 5.2+/-0.9% (off steroids) and 6.2+/-2.1% (on steroids, P = 0.02), and mean serum creatinine levels were 1.4+/-0.8 mg/dl (off steroids) and 1.7+/-1.0 mg/dl (on steroids, P = 0.02).

CONCLUSION

These data show for the first time that steroid withdrawal can be safely accomplished in pancreas transplant recipients maintained on tacrolimus-based immunosuppression. Steroid withdrawal is associated with excellent patient and graft survival with no increase in the cumulative risk of rejection.

Simultaneous kidney-pancreas transplantation without antilymphocyte induction

BACKGROUND

The introduction of potent new immunosuppressive agents may allow simultaneous kidney-pancreas transplantation to be performed without antilymphocyte induction.

METHODS

We analyzed 30 simultaneous kidney-pancreas transplantations receiving tacrolimus, mycophenolate mofetil, and steroids without without antilymphocyte induction. Eighteen patients underwent pancreas transplantation with portal-enteric (P-E) drainage and the remaining 12 had systemic bladder (S-B) drainage. Target 12 hr trough tacrolimus levels for the first 3 months after simultaneous kidney-pancreas transplantation were 15-20 ng/ml. The oral mycophenolate mofetil dose was 2-3 g/day begun immediately posttransplant in two to four divided doses. Steroids were tapered according to protocol.

RESULTS

All patients experienced immediate function of both kidney and pancreas grafts. One-year actuarial patient, kidney, and pancreas graft survival rates are 93, 93, and 90%, respectively. Nine patients (30%) had a total of 13 rejection episodes (12 biopsy proven) including 4 within 2 weeks, 6 between 2 weeks and 3 months, and 3 beyond 3 months after simultaneous kidney-pancreas transplantation. Three rejection episodes were treated with steroids alone and 10 were treated with antilymphocyte therapy (5 OKT3 and 5 ATGAM). A total of seven patients (23%) received antilymphocyte therapy. Three patients (10%) had more than one rejection episode. Two pancreas grafts (7%) and one kidney graft (3%) were lost from rejection. Four patients (13%) developed cytomegalovirus infection, but none had tissue-invasive cytomegalovirus. At present, 22 surviving patients (81%) remain on triple immunosuppression with tacrolimus, mycophenolate mofetil, and prednisone with excellent dual graft function.

CONCLUSION

Tacrolimus, mycophenolate mofetil, and prednisone immunosuppression without without antilymphocyte induction is safe and effective after simultaneous kidney-pancreas transplantation.

Allograft pancreatectomy after pancreas transplantation with systemic-bladder versus portal-enteric drainage

From 1989 to 1997, we performed 159 pancreas transplantations (PTXs), including 117 simultaneous kidney PTX (SKPT), 25 PTXs alone (PTA), and 17 sequential PTXs after kidney transplantations (PAKT). A total of 73 PTXs were performed with systemic-bladder (S-B) and 86 with portal-enteric (P-E) drainage. The need for allograft pancreatectomy (PCTY) may be considered as an index of technical morbidity after PTX. A total of 37 PCTYs (23%) were performed at a mean of 4.7 months after PTX. Twenty-seven PCTYs were performed within 1 month, 30 (81%) within 3 months, and the remaining seven more than 6 months after PTX. The incidence of PCTY did not differ according to type of transplantation: simultaneous kidney PTX (SKPT) (23%), PTA (24%), and PAKT (23.5%). Indications for PCTY were thrombosis (23), rejection (9), infection (3), and pancreatitis (2). During the study, a total of 70 pancreas grafts were lost, with PCTY performed in 37 (53%). PCTY was directly related to the timing of graft loss; 77% of grafts lost within 3 months of PTX required PCTY, while 25% of grafts lost after 3 months resulted in PCTY (p < 0.01). The incidence of graft failure resulting in PCTY was similar according to type of transplantation: SKPT (55%), PTA (46%), and PAKT (50%). The incidence of PCTY was also similar according to technique of transplantation: 26% S-B versus 21% P-E, p = NS. However, the incidence of graft failure resulting in PCTY was higher in P-E (69%) versus S-B (43%) (p < 0.05) PTX recipients. Patient and kidney graft survival and pancreas retransplant graft survival rates were higher in PTX recipients with P-E drainage.

CONCLUSIONS

PCTY is performed in over half of cases of pancreas allograft loss and is directly related to the timing and cause of graft loss. The incidence of PCTY is neither related to the type nor technique of PTX. The lower overall incidence of graft loss after PTX with P-E drainage is offset by a higher incidence of PCTY in these grafts that fail. These results suggest that whole-organ PTX with P-E drainage does not place the patient at an increased risk for PCTY and does not preclude successful pancreas retransplantation.

A20 inhibits cytokine-induced apoptosis and nuclear factor kappaB-dependent gene activation in islets

Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease resulting from apoptotic destruction of beta cells in the islets of Langerhans. Low expression of antioxidants and a predilection to produce nitric oxide (NO) have been shown to underscore beta cell apoptosis. With this perspective in mind, we questioned whether beta cells could mount an induced protective response to inflammation. Here we show that human and rat islets can be induced to rapidly express the antiapoptotic gene A20 after interleukin (IL)-1beta activation. Overexpression of A20 by means of adenovirus-mediated gene transfer protects islets from IL-1beta and interferon gamma-induced apoptosis. The cytoprotective effect of A20 against apoptosis correlates with and is dependent on the abrogation of cytokine-induced NO production. The inhibitory effect of A20 on cytokine-stimulated NO production is due to transcriptional blockade of inducible NO synthase (iNOS) induction; A20 inhibits the activation of the transcription factor nuclear factor kappaB at a level upstream of IkappaBalpha degradation. These data demonstrate a dual antiapoptotic and antiinflammatory function for A20 in beta cells. This qualifies A20 as part of the physiological cytoprotective response of islets. We propose that A20 may have therapeutic potential as a gene therapy candidate to achieve successful islet transplantation and the cure of IDDM.

Evolution in pancreas transplantation techniques: simultaneous kidney-pancreas transplantation using portal-enteric drainage without antilymphocyte induction

OBJECTIVE

To report initial experience with the combination of a novel technique of portal-enteric pancreas transplantation with newer immunosuppressive strategies that eliminate antilymphocyte induction therapy.

BACKGROUND

A new surgical technique of pancreas transplantation has been developed with portal venous delivery of insulin and enteric drainage of the exocrine secretions (portal-enteric). The introduction of potent immunosuppressive agents may allow simultaneous kidney and pancreas transplants (SKPT) to be performed without antilymphocyte induction.

METHODS

From September 1996 to November 1998, the authors performed 28 primary SKPTs with portal-enteric drainage and no antilymphocyte induction. All patients received triple immunosuppression with tacrolimus, mycophenolate mofetil, and steroids. The study group had a mean age of 38 years and a mean preoperative duration of diabetes of 25 years. Four patients (14%) had prior kidney transplants.

RESULTS

All patients had immediate renal allograft function. Actual patient, kidney, and pancreas graft survival rates were 86%, 82%, and 82%, respectively, after a mean follow-up of 12 months. Four patients died, three as a result of cardiac events unrelated to SKPT. Five kidney and five pancreas grafts were lost, including five deaths with function and three cases of chronic rejection. The mean length of stay and total charges for the initial hospital stay were 12.5 days and $99,517. The mean number of readmissions was 2.9, and 10 patients (36%) had no readmissions. Six patients (21 %) developed acute rejection, with five (18%) receiving antilymphocyte therapy. Seven patients (25%) underwent relaparotomy, including two (7%) for intraabdominal infection. Nine patients (32%) had major infections, including three (11%) with cytomegaloviral infection. Of the 24 surviving patients, 22 (92%) are both dialysis- and insulin-free.

CONCLUSION

These preliminary results suggest that SKPT with portal-enteric drainage without antilymphocyte induction can be performed with excellent outcomes.