Pretransplantation GAD-autoantibody status to guide prophylactic antibody induction therapy in simultaneous pancreas and kidney transplantation. Transplantation. 2013;96:745-752. [PMID: 23912172 DOI: 10.1097/tp.0b013e3182a012cc]

Batch-to-Batch Variation and Patient Heterogeneity in Thymoglobulin Binding and Specificity: One Size Does Not Fit All

Background: Thymoglobulin is used to prevent allograft rejection and is being explored at low doses as intervention immunotherapy in type 1 diabetes. Thymoglobulin consists of a diverse pool of rabbit antibodies directed against many different targets on human thymocytes that can also be expressed by other leukocytes. Since Thymoglobulin is generated by injecting rabbits with human thymocytes, this conceivably leads to differences between Thymoglobulin batches. Methods: We compared different batches for antibody composition and variation between individuals in binding to PBMC and T cell subsets, and induction of cytokines. Four different batches of Thymoglobulin were directly conjugated with Alexa-Fluor 647. Blood was collected from five healthy donors, and PBMCs were isolated and stained with Thymoglobulin followed or preceded by a panel of fluorescent antibodies to identify PBMC and T cell subsets. In addition, whole blood was incubated with unlabeled Thymoglobulin to measure cytokine induction. Results: Cluster analysis of flow cytometry data shows that Thymoglobulin bound to all PBMC subpopulations including regulatory T cells. However, Thymoglobulin binding was highly variable between donors and to a lesser extent between batches. Cytokines related to cytokine release syndrome were highly, but variably, increased by all Thymoglobulin batches, with strong differences between donors and moderate differences between batches. Discussion: The variation in Thymoglobulin binding and action between donors regarding PBMC recognition and cytokine response may underlie the different clinical responses to Thymoglobulin therapy and require personalized dose adjustment to maximize efficacy and minimize adverse side effects.

Simultaneous Pancreas-Kidney Transplant Outcomes Stratified by Autoantibodies Status and Pretransplant Fasting C-peptide

BACKGROUNDS

Pancreatic beta cell function and islet autoantibodies classically distinguish types of diabetes (type 1 diabetes mellitus [DM] or type 2 DM). Here, we sought to evaluate simultaneous pancreas-kidney (SPK) transplant outcomes stratified by the presence or absence of beta cell function and autoantibodies.

METHODS

SPK recipients were eligible if pretransplant autoantibodies were measured against insulin, islet cell, or glutamic acid decarboxylase 65-kD isoform. Recipients were categorized as A+ or A- based on the detection of ≥1 autoantibodies. Recipients were similarly categorized on the basis of detectable pretransplant fasting C-peptide of ≥2 ng/mL (β+) or <2 ng/mL (β-). Thus, recipients were categorized into 4 groups: A+β-, A-β-, A-β+, and A+β+. Outcomes of interest were overall pancreas graft failure (non-death-censored), death-censored pancreas, or kidney graft failure (death-censored pancreas graft failure [DCGF]; kidney DCGF), composite outcomes with any of the 3 outcomes as pancreas DCGF, use of an antidiabetic agent, or hemoglobin A1c >6.5.

RESULTS

One hundred eighty-three SPK recipients were included: A+β- (n = 72), A-β- (n = 42), A-β+ (n = 49), and A+β+ (n = 20). We did not detect a statistical difference in non-death-censored pancreas graft failure for A+β- recipients compared with other groups: A-β- (adjusted hazard ratio [aHR]: 0.44; 95% confidence interval [CI], 0.14-1.42), A-β+ (aHR: 1.02; 95% CI, 0.37-2.85), and A+β+ (aHR: 0.67; 95% CI, 0.13-3.33) in adjusted analyses. Similar outcomes were observed for other outcomes.

CONCLUSIONS

In SPK recipients, outcomes were similar among recipients with classic features of type 1 DM and various other types of DM.

Impact of GAD65 and IA2 autoantibodies on islet allograft survival

Introduction

Islet transplantation (ITx) shows promise in treating T1D, but the role of islet autoantibodies on graft survival has not been clearly elucidated. We aimed to analyze the effect of GAD65 and IA2 autoantibody status on graft survival and attainment of insulin independence in subjects with T1D who underwent ITx.

Method

We conducted a retrospective cohort study on 47 ITx recipients from 2000 to 2018. Islet infusion was performed via intrahepatic portal (n=44) or onto the omentum via laparoscopic approach (n=3). Immunosuppression involved anti-IL2 receptor antibody, anti-TNF, and dual combinations of sirolimus, tacrolimus, or mycophenolate mofetil (Edmonton-like) in 38 subjects (80.9%). T-cell depletion induction with Edmonton-like maintenance was used in 9 subjects (19%). GAD65 and IA2 autoantibodies were assessed pre-transplant and post-transplant (monthly) until graft failure, and categorized as persistently negative, persistently positive, or seroconverters. Graft survival was analyzed using U-Mann-Whitney test, and Quade's nonparametric ANCOVA adjusted for confounders. Kaplan-Meier and Log-Rank tests were employed to analyze attainment of insulin independence. P value <0.05 indicated statistical significance.

Results

ITx recipients with persistent autoantibody negativity (n = 21) showed longer graft function (98 [61 - 182] months) than those with persistent autoantibody positivity (n = 18; 38 [13 - 163] months), even after adjusting for immunosuppressive induction protocol (P = 0.027). Seroconverters (n=8) had a median graft survival time of 73 (7.7 - 167) months, which did not significantly differ from the other 2 groups. Subjects with persistently single antibody positivity to GAD65 (n = 8) had shorter graft survival compared to negative islet autoantibody (GAD65/IA2) subjects (n = 21; P = 0.016). Time of graft survival did not differ in subjects with single antibody positivity to IA2. The proportion of insulin independence attainment was similar irrespective of autoantibody status.

Conclusion

The persistence of islet autoantibodies, as markers of islet autoimmunity, may represent an underappreciated contributing factor to the failure of transplanted β cells. Whether induction with T-cell depletion may lead to improved graft survival, independent of islet autoantibody status, could not be evaluated in our cohort. Larger prospective studies are needed to further address the role of islet autoantibody status on islet graft survival.

The need and benefit of immune monitoring to define patient and disease heterogeneity, mechanisms of therapeutic action and efficacy of intervention therapy for precision medicine in type 1 diabetes

The current standard of care for type 1 diabetes patients is limited to treatment of the symptoms of the disease, insulin insufficiency and its complications, not its cause. Given the autoimmune nature of type 1 diabetes, immunology is critical to understand the mechanism of disease progression, patient and disease heterogeneity and therapeutic action. Immune monitoring offers the key to all this essential knowledge and is therefore indispensable, despite the challenges and costs associated. In this perspective, I attempt to make this case by providing evidence from the past to create a perspective for future trials and patient selection.

Superior Long-term Survival for Simultaneous Pancreas-Kidney Transplantation as Renal Replacement Therapy: 30-Year Follow-up of a Nationwide Cohort

OBJECTIVE

In patients with type 1 diabetes and end-stage renal disease, it is controversial whether a simultaneous pancreas-kidney (SPK) transplantation improves survival compared with kidney transplantation alone. We compared long-term survival in SPK and living- or deceased-donor kidney transplant recipients.

RESEARCH DESIGN AND METHODS

We included all 2,796 patients with type 1 diabetes in the Netherlands who started renal replacement therapy between 1986 and 2016. We used multivariable Cox regression analyses adjusted for recipient age and sex, dialysis modality and vintage, transplantation era, and donor age to compare all-cause mortality between deceased- or living-donor kidney and SPK transplant recipients. Separately, we analyzed mortality between regions where SPK transplant was the preferred intervention (80% SPK) versus regions where a kidney transplant alone was favored (30% SPK).

RESULTS

Of 996 transplanted patients, 42%, 16%, and 42% received a deceased- or living-donor kidney or SPK transplant, respectively. Mean (SD) age at transplantation was 50 (11), 48 (11), and 42 (8) years, respectively. Median (95% CI) survival time was 7.3 (6.2; 8.3), 10.5 (7.2; 13.7), and 16.5 (15.1; 17.9) years, respectively. SPK recipients with a functioning pancreas graft at 1 year (91%) had the highest survival (median 17.4 years). Compared with deceased-donor kidney transplant recipients, adjusted hazard ratios (95% CI) for 10- and 20-year all-cause mortality were 0.79 (0.49; 1.29) and 0.98 (0.69; 1.39) for living-donor kidney and 0.67 (0.46; 0.98) and 0.79 (0.60; 1.05) for SPK recipients, respectively. A treatment strategy favoring SPK over kidney transplantation alone showed 10- and 20-year mortality hazard ratios of 0.56 (0.40; 0.78) and 0.69 (0.52; 0.90), respectively.

CONCLUSIONS

Compared with living- or deceased-donor kidney transplantation, SPK transplant was associated with improved patient survival, especially in recipients with a long-term functioning pancreatic graft, and resulted in an almost twofold lower 10-year mortality rate.

Development of immune response to tissue-restricted self-antigens in simultaneous kidney-pancreas transplant recipients with acute rejection

Simultaneous kidney-pancreas transplantation (SKP Tx) is a treatment for end-stage kidney disease secondary to diabetes mellitus. We investigated the role of immune responses to donor human leukocyte antigens (HLA) and tissue-restricted kidney and pancreas self-antigens (KSAgs and PSAgs, respectively) in SKP Tx recipients (SKP TxRs). Sera collected from 39 SKP TxRs were used to determine de novo Abs specific for KSAgs (collagen-IV, Col-IV; fibronectin, FN) and PSAgs (insulin, islet cells, glutamic acid decarboxylase, and pancreas-associated protein-1) by ELISA. KSAg-specific IFN-γ, IL-17, and IL-10 cytokines were enumerated by ELISpot. Abs to donor HLA classes I and II were determined by Luminex assay. Abs to KSAgs and PSAgs were detectable in recipients with rejection compared with stable recipients (P<.05). Kidney-only rejection recipients had increased Abs against KSAgs compared with stable (P<.05), with no increase in Abs against PSAgs. Pancreas-only rejection recipients showed increased Abs against PSAgs compared to stable (P<.05), with no Abs against KSAgs. SKP TxRs with rejection showed increased frequencies of KSAg-specific IFN-γ and IL-17 with reduction in IL-10-secreting cells. SKP TxRs with rejection developed Abs to KSAgs and PSAgs demonstrated increased frequencies of kidney or pancreas SAg-specific IFN-γ and IL-17-secreting cells with reduced IL-10, suggesting loss of peripheral tolerance to SAgs.

Alemtuzumab Induction and Delayed Acute Rejection in Steroid-Free Simultaneous Pancreas-Kidney Transplant Recipients

Supplemental digital content is available in the text.

Background

The optimal immunosuppressive regimen in simultaneous pancreas-kidney transplant (SPKT) recipients that prevents acute rejection episodes (AREs) and allows optimal outcome remains elusive.

Methods

This cohort study assessed incidence and time to AREs in 73 consecutive SPKT recipients receiving alemtuzumab induction and steroid-free maintenance with tacrolimus and mycophenolate mofetil. A cohort with single high-dose antithymocyte globulin (ATG; n = 85) and triple therapy served as controls. In addition, we provided mechanistic insights in AREs after alemtuzumab depletion, including composition and alloreactivity of lymphocytes (flow cytometry and mixed lymphocyte reaction) plasma alemtuzumab levels (enzyme-linked immunosorbent assay), and maintenance drug exposure.

Results

Overall number of AREs at 3 years was significantly lower with alemtuzumab versus ATG induction (26.0% vs 43.5%; adjusted hazard ratio, 0.38; P = 0.029). Most AREs (94.6%) with ATG occurred within the first month, whereas 84.2% of AREs with alemtuzumab occurred beyond 3 months. Patients with and without an ARE in the steroid-free alemtuzumab group showed no differences in composition of lymphocytes, or in alemtuzumab levels. Of note, more than two thirds of these AREs were preceded by empiric tacrolimus and/or mycophenolate mofetil dose adjustments due to viral infections, leukopenia, or gastrointestinal symptoms.

Conclusions

Alemtuzumab induction resulted in a significant lower incidence of AREs. Empiric dose adjustments beyond 3 months in the absence of steroids carry a significant risk for subsequent rejection in SPKT recipients.

The dorsal pancreatic artery in pancreas procurement and transplantation: anatomical considerations and potential implications

AIM

Organ procurement errors account for almost 20% of discarded pancreatic allografts. For this reason, the anatomical significance of the dorsal pancreatic artery (DPA) was reviewed.

METHODS

A strategy on dealing with an often overlooked DPA is evaluated.

RESULTS

The DPA provides together with the splenic artery the main blood supply to the pancreatic tail. Three different arterial variations have been described. In the rare instances when the DPA arises from the common hepatic artery or the celiac trunk, instead of the splenic origin, the DPA can easily be overlooked by surgeons not familiar with this artery. This may result in an unintentional damage to the pancreatic tail blood supply. If unrecognized during the back-table inspection, it could potentially jeopardize the pancreatic graft after reperfusion. When a cut DPA is encountered during inspection, efforts should be attempted to revascularize the graft, especially if there is no backflow from the splenic artery as sign of absent collateral circulation.

CONCLUSION

The DPA may play a more prominent role in the vascularization of pancreas transplants than currently assumed. Better understanding of the vascular anatomy may lead to improved results in pancreas transplantation.

Where, How, and When: Positioning Posttranslational Modification Within Type 1 Diabetes Pathogenesis

Autoreactive T cells specific for islet autoantigens develop in type 1 diabetes (T1D) by escaping central as well as peripheral tolerance. The current paradigm for development of islet autoimmunity is just beginning to include the contribution of posttranslationally modified (PTM) islet autoantigens, for which the immune system may be ignorant rather than tolerant. As a result, PTM is the latest promising lead in the quest to understand how the break in peripheral tolerance occurs in T1D. However, it is not completely clear how, where, or when these modifications take place. Currently, only a few PTM antigens have been well-thought-out or identified in T1D, and methods for identifying and characterizing new PTM antigens are rapidly improving. This review will address both reported and potential new sources of modified islet autoantigens and discuss how islet neo-autoantigen generation may contribute to the development and progression of T1D.

Risk Factors for Type 1 Diabetes Recurrence in Immunosuppressed Recipients of Simultaneous Pancreas-Kidney Transplants

Patients with type 1 diabetes (T1D) who are recipients of pancreas transplants are believed to rarely develop T1D recurrence in the allograft if effectively immunosuppressed. We evaluated a cohort of 223 recipients of simultaneous pancreas-kidney allografts for T1D recurrence and its risk factors. With long-term follow-up, recurrence was observed in approximately 7% of patients. Comparing the therapeutic regimens employed in this cohort over time, lack of induction therapy was associated with recurrence, but this occurs even with the current regimen, which includes induction; there was no influence of maintenance regimens. Longitudinal testing for T1D-associated autoantibodies identified autoantibody positivity, number of autoantibodies, and autoantibody conversion after transplantation as critical risk factors. Autoantibodies to the zinc transporter 8 had the strongest and closest temporal association with recurrence, which was not explained by genetically encoded amino acid sequence donor-recipient mismatches for this autoantigen. Genetic risk factors included the presence of the T1D-predisposing HLA-DR3/DR4 genotype in the recipient and donor-recipient sharing of HLA-DR alleles, especially HLA-DR3. Thus, T1D recurrence is not uncommon and is developing in patients treated with current immunosuppression. The risk factors identified in this study can be assessed in the transplant clinic to identify recurrent T1D and may lead to therapeutic advances.

Tyrosine-phosphatase and glutamate-decarboxylase antibodies after simultaneous pancreas kidney transplantation: do they have an impact on pancreas graft survival?

INTRODUCTION

The pathogenesis of type 1 diabetes mellitus (T1DM) is associated with auto-antibodies. These auto-antibodies contribute to pancreatic ß-cell destruction. Tyrosine-phosphatases (IA-2) and glutamic acid decarboxylase (GAD65) are the most frequently used by clinicians. When T1DM patients develops advanced chronic kidney disease, simultaneous pancreas-kidney (SPK) transplantation becomes the best option. However, pancreatic graft survival is limited. The role of the auto-antibodies on pancreas graft survival remains controversial.

OBJECTIVE

The aim of this study was to assess pancreas graft survival according to the presence of GAD65 and IA-2 auto-antibodies after SPK transplantation.

METHODS

We analyzed all SPK transplantations performed in our hospital since January 1990 to December 2013 with at least 30 days of pancreas graft survival. We collected demographic and clinical variables from donors and recipients. Graft failure was defined as complete insulin independence after transplantation. Pancreatic graft survival was analyzed using the Kaplan-Meier method.

RESULTS

Overall, 152 SPK transplantations were performed during the period. One hundred sixteen were accessed for de novo post-transplantation auto-antibodies. Also, 17.8% (n = 27) were positive for anti-GAD65, 13.8% (n = 20) for IA-2, 3.9% (n = 6) were positive for both, and the rest were negative for any auto-antibody (n = 63). Kaplan-Meier survival curves estimated a worst pancreas graft survival for patients with positive IA-2 antibodies versus those patients with negative auto-antibodies and GAD65+auto-antibodies (P = .003 and .022, respectively, by log-rank). Mean pancreas graft survival rates at first and fifth year were 72% and 64%, respectively, for those patients with positive IA-2.

CONCLUSIONS

IA-2 antibodies after SPK transplantation are associated with long-term graft lost compared with the rest of the groups. Monitoring of these auto-antibodies after SPK may help to identify patients with a higher risk of graft failure.

Autoimmune diabetes recurrence should be routinely monitored after pancreas transplantation

Autoimmune type 1 diabetes recurrence in pancreas grafts was first described 30 years ago, but it is not yet completely understood. In fact, the number of transplants affected and possibly lost due to this disease may be falsely low. There may be insufficient awareness to this entity by clinicians, leading to underdiagnosis. Some authors estimate that half of the immunological losses in pancreas transplantation are due to autoimmunity. Pancreas biopsy is the gold standard for the definitive diagnosis. However, as an invasive procedure, it is not the ideal approach to screen the disease. Pancreatic autoantibodies which may be detected early before graft dysfunction, when searched for, are probably the best initial tool to establish the diagnosis. The purpose of this review is to revisit the autoimmune aspects of type 1 diabetes and to analyse data about the identified autoantibodies, as serological markers of the disease. Therapeutic strategies used to control the disease, though with unsatisfactory results, are also addressed. In addition, the author’s own experience with the prospective monitoring of pancreatic autoantibodies after transplantation and its correlation with graft outcome will be discussed.