Acute cellular and antibody-mediated rejection of the pancreas allograft: incidence, risk factors and outcomes

Simultaneous combined transplantation: Intricacies in immunosuppression management

Simultaneous combined transplantation (SCT), i.e. the transplantation of two solid organs within the same procedure, can be required when the patients develop more than one end-stage organ failure. The development of SCT over the last 20 years could only be possible thanks to progress in the surgical techniques and in the perioperative management of patients in an ageing population. Performing such major transplant surgeries from the same donor, in a short amount of time, and in critical pathophysiological conditions, is often considered to be counterbalanced by the immune benefits expected from these interventions. However, SCT includes a wide array of different transplant combinations, with each time a different immunological constellation. Recent research offers new insights into the immune mechanisms involved in these different settings. Progress in the understanding of these immunological intricacies help to address the optimal induction and maintenance immunosuppressive treatment strategies. In this review, we summarize the different immunological benefits according to the type of SCT performed. We also incorporate the main outcomes according to the immunological risk at transplantation, and the deleterious impact of preformed or de novo donor-specific antibodies (DSA) in the different types of SCT. Finally, we propose comprehensive and evidence-based induction and maintenance immunosuppression strategies guided by the type of SCT.

Banff 2022 pancreas transplantation multidisciplinary report: Refinement of guidelines for T cell-mediated rejection, antibody-mediated rejection and islet pathology. Assessment of duodenal cuff biopsies and noninvasive diagnostic methods

The Banff pancreas working schema for diagnosis and grading of rejection is widely used for treatment guidance and risk stratification in centers that perform pancreas allograft biopsies. Since the last update, various studies have provided additional insight regarding the application of the schema and enhanced our understanding of additional clinicopathologic entities. This update aims to clarify terminology and lesion description for T cell-mediated and antibody-mediated allograft rejections, in both active and chronic forms. In addition, morphologic and immunohistochemical tools are described to help distinguish rejection from nonrejection pathologies. For the first time, a clinicopathologic approach to islet pathology in the early and late posttransplant periods is discussed. This update also includes a discussion and recommendations on the utilization of endoscopic duodenal donor cuff biopsies as surrogates for pancreas biopsies in various clinical settings. Finally, an analysis and recommendations on the use of donor-derived cell-free DNA for monitoring pancreas graft recipients are provided. This multidisciplinary effort assesses the current role of pancreas allograft biopsies and offers practical guidelines that can be helpful to pancreas transplant practitioners as well as experienced pathologists and pathologists in training.

Analysis of Individual Components of Frailty in Simultaneous Pancreas and Kidney, and Solitary Pancreas Transplant Recipients

Backgrounds

It is not known which of the 5 components of the Fried frailty score have the most predictive value for outcomes in simultaneous pancreas-kidney transplant (SPK) and solitary pancreas transplant (SPT) recipients.

Methods

In this study, we sought to investigate the association between pretransplant overall frailty and individual frailty components, with posttransplant outcomes among SPK and SPT recipients. Outcomes of interest were length of stay, kidney delayed graft function (K-DGF), readmission within 30 d after discharge, cardiovascular events, acute rejection, pancreas death-censored graft failure (DCGF), kidney DCGF, and death.

Results

Of the individual frailty components among SPK (n = 113), only slow walk time was associated with an increased risk of mortality (adjusted odds ratio [aOR]: 4.99; P = 0.03). Among SPT (n = 49), higher sum frailty scores (coefficient correlation 0.29; P = 0.04) and weight loss (coefficient correlation  = 0.30; P = 0.03) were associated with prolonged length of stay. Similarly, weight loss among SPT was associated with an increased risk of DCGF (aOR: 4.34; P = 0.049). Low grip strength was strongly associated with an increased risk of early readmission (aOR: 13.08; P = 0.008).

Conclusions

We found that not all components of frailty contribute equally to predicting outcomes. Objective measurements of slow walk time, unintentional weight loss, and low grip strength were found to be associated with less optimal outcomes in pancreas transplant recipients. Targeted interventions may improve posttransplant outcomes.

An Initial Analysis of the Baseline Levels of Dd-cfDNA After Pancreas Transplantation: A Prospective Study From High-volume Centers in the United States

Pancreas transplantation offers patients with diabetes an opportunity for glucose homeostasis. Current blood tests to surveil for rejection have poor sensitivity and specificity for identifying rejection, and pancreas biopsies are challenging and associated with morbidity and graft loss. Donor-derived cell-free DNA (dd-cfDNA) is shed from transplanted organs and detectable in peripheral blood. Thus, a potential dd-cfDNA blood test assessing rejection would be clinically advantageous.

Methods

One hundred eighty-one dd-cfDNA samples (n) were collected from 77 patients (N) up to 132 mo posttransplant.

Results

The median dd-cfDNA level among all subjects was 0.28% (0.13%, 0.71%). In simultaneous pancreas-kidney (SPK) transplant recipients, the median dd-cfDNA level was 0.29% (0.13%, 0.71%), and it was 0.23% (0.08%, 0.71%) in pancreas transplant alone (PTA) recipients. When isolating for when without infection or rejection, the median dd-cfDNA level was 0.28% (0.13%, 0.64%) for SPK and 0.20% (0.00%, 0.32%) for PTA. Both transplant types approached 1.0% ≤1 mo posttransplant followed by a decrease in median dd-cfDNA. During episodes of rejection or infection, median dd-cfDNA levels were greater among all transplant types.

Conclusions

The mean dd-cfDNA level for all pancreas transplant recipients is <1.0%, consistent with the published kidney transplant rejection threshold (>1.0%), regardless of SPK or PTA. Early posttransplant dd-cfDNA levels are transiently higher than later measurements. Dd-cfDNA elevation also correlates with rejection and infection and thus is a promising biomarker for surveilling pancreas transplant dysfunction.

eATP and autoimmune diabetes

PURPOSE OF REVIEW

The purine nucleotide adenosine triphosphate (ATP) is released into extracellular spaces as extracellular ATP (eATP) as a consequence of cell injury or death and activates the purinergic receptors. Once released, eATP may facilitate T-lymphocyte activation and differentiation. The purpose of this review is to elucidate the role of ATP-mediated signaling in the immunological events related to type 1 diabetes (T1D).

RECENT FINDINGS

T lymphocytes mediate immune response during the onset of T1D and promote pancreatic islet or whole pancreas rejection in transplantation. Recent data suggest a potential role for eATP in early steps of T1D onset and of allograft rejection. In different preclinical experimental models and clinical trials, several drugs targeting purinergic signaling have been employed to abrogate lymphocyte activation and differentiation, thus representing an achievable treatment to prevent/revert T1D or to induce long-term islet allograft function.

SUMMARY

In preclinical and clinical settings, eATP-signaling inhibition induces immune tolerance in autoimmune disease and in allotransplantation. In this view, the purinergic system may represent a novel therapeutic target for auto- and allo-immunity.

Immune Profiling of Peripheral Blood Mononuclear Cells at Pancreas Acute Rejection Episodes in Kidney-Pancreas Transplant Recipients

Profiling of circulating immune cells provides valuable insight to the pathophysiology of acute rejection in organ transplantation. Herein we characterized the peripheral blood mononuclear cells in simultaneous kidney-pancreas transplant recipients. We conducted a retrospective analysis in a biopsy-matched cohort (n = 67) and compared patients with biopsy proven acute rejection (BPAR; 41%) to those without rejection (No-AR). We observed that CD3+ T cells, both CD8+ and CD4+, as well as CD19+ B cells were increased in patients with BPAR, particularly in biopsies performed in the early post-transplant period (<3 months). During this period immune subsets presented a good discriminative ability (CD4+ AUC 0.79; CD8+ AUC 0.80; B cells AUC 0.86; p < 0.05) and outperformed lipase (AUC 0.62; p = 0.12) for the diagnosis of acute rejection. We further evaluated whether this could be explained by differences in frequencies prior to transplantation. Patients presenting with early post-transplant rejection (<3 months) had a significant increase in T-cell frequencies pre-transplant, both CD4+ T cells and CD8+ T cells (p < 0.01), which were associated with a significant inferior rejection-free graft survival. T cell frequencies in peripheral blood correlated with pancreas acute rejection episodes, and variations prior to transplantation were associated with pancreas early acute rejection.

Donor-derived Cell-free DNA Shows High Sensitivity for the Diagnosis of Pancreas Graft Rejection in Simultaneous Pancreas-kidney Transplantation

BACKGROUND

Pancreas graft status in simultaneous pancreas-kidney transplant (SPKTx) is currently assessed by nonspecific biochemical markers, typically amylase or lipase. Identifying a noninvasive biomarker with good sensitivity in detecting early pancreas graft rejection could improve SPKTx management.

METHODS

Here, we developed a pilot study to explore donor-derived cell-free DNA (dd-cfDNA) performance in predicting biopsy-proven acute rejection (P-BPAR) of the pancreas graft in a cohort of 36 SPKTx recipients with biopsy-matched plasma samples. dd-cfDNA was measured using the Prospera test (Natera, Inc.) and reported both as a fraction of the total cfDNA (fraction; %) and as concentration in the recipient's plasma (quantity; copies/mL).

RESULTS

In the absence of P-BPAR, dd-cfDNA was significantly higher in samples collected within the first 45 d after SPKTx compared with those measured afterward (median, 1.00% versus 0.30%; median, 128.2 versus 35.3 cp/mL, respectively with both; P  = 0.001). In samples obtained beyond day 45, P-BPAR samples presented a significantly higher dd-cfDNA fraction (0.83 versus 0.30%; P  = 0.006) and quantity (81.3 versus 35.3 cp/mL; P  = 0.001) than stable samples. Incorporating dd-cfDNA quantity along with dd-cfDNA fraction outperformed dd-cfDNA fraction alone to detect active rejection. Notably, when using a quantity cutoff of 70 cp/mL, dd-cfDNA detected P-BPAR with a sensitivity of 85.7% and a specificity of 93.7%, which was more accurate than current biomarkers (area under curve of 0.89 for dd-cfDNA (cp/ml) compared with 0.74 of lipase and 0.46 for amylase).

CONCLUSIONS

dd-cfDNA measurement through a simple noninvasive blood test could be incorporated into clinical practice to help inform graft management in SPKTx patients.

Results after 13 years of kidney-pancreas transplantation in type 1 diabetic patients in Comunidad Valenciana

INTRODUCTION

Simultaneous pancreas-kidney (SPK) transplant is a proven option of treatment for patients with type 1 diabetes mellitus and related end-stage renal disease, who are candidates for kidney transplantation. The results from the beginning of SPK transplant program in Comunidad Valenciana are presented.

METHODS

Descriptive, retrospective, and single-center study of the pancreas transplant performed at the Hospital Universitari i Politècnic La Fe, from September 2002 to December 2015. Clinical variables from donors and recipients, peri-operative variables, patient survival, and pancreatic graft survival were collected.

RESULTS

Eighty-one patients with type 1 diabetes mellitus (48 males and 33 females, mean age 37.4 ± 5.7 years, mean BMI 24.1 ± 3.4 kg/m², mean duration of diabetes 25.5 ± 6.5 years) received SPK transplantation. The overall patient survival at one, 3, and 5 years were 91.3%, 91.3% and 89.5%, respectively. However, patient survival in the periods 2002-2008 and 2009-2015 were 88.2% and 93.6% at one year, 88.2% and 93.7% at 3 years, and 85.3% and 93.7% at 5 years, respectively (P = 1). The overall pancreatic graft survival at one, 3, and 5 years were 75.2%, 69.1% and 63.2%, respectively. On the other hand, pancreatic graft survival in the periods 2002-2008 and 2009-2015 were 67.5% and 80.6% at one year, 64.7% and 71.8% at 3 years, and 58.8% and 65.3% at 5 years, respectively (P = .0109). Post-transplant complications were: graft rejection 8.6%, venous graft thrombosis 7.4%, graft pancreatitis 4.9%.

CONCLUSIONS

In 13 years' experience of SPK transplantation, patient and pancreatic graft survival and the rate of complications after pancreas transplantation were similar to those of other larger series. The medical-surgical team experience improves pancreatic graft survival without influencing patient survival.

First World Consensus Conference on pancreas transplantation: Part II - recommendations

The First World Consensus Conference on Pancreas Transplantation provided 49 jury deliberations regarding the impact of pancreas transplantation on the treatment of diabetic patients, and 110 experts' recommendations for the practice of pancreas transplantation. The main message from this consensus conference is that both simultaneous pancreas-kidney transplantation (SPK) and pancreas transplantation alone can improve long-term patient survival, and all types of pancreas transplantation dramatically improve the quality of life of recipients. Pancreas transplantation may also improve the course of chronic complications of diabetes, depending on their severity. Therefore, the advantages of pancreas transplantation appear to clearly surpass potential disadvantages. Pancreas after kidney transplantation increases the risk of mortality only in the early period after transplantation, but is associated with improved life expectancy thereafter. Additionally, preemptive SPK, when compared to SPK performed in patients undergoing dialysis, appears to be associated with improved outcomes. Time on dialysis has negative prognostic implications in SPK recipients. Increased long-term survival, improvement in the course of diabetic complications, and amelioration of quality of life justify preferential allocation of kidney grafts to SPK recipients. Audience discussions and live voting are available online at the following URL address: http://mediaeventi.unipi.it/category/1st-world-consensus-conference-of-pancreas-transplantation/246.

Pancreas transplant with enteric drainage at a single institute in Asia

BACKGROUND/OBJECTIVE

This study is to assess immunological and graft survival outcomes after pancreas transplant at a single institute in Asia.

METHODS

Patients undergoing pancreas transplant with enteric drainage were included. Clinical data and outcomes were evaluated and compared between each subgroup.

RESULTS

There were 165 cases of pancreas transplant, including 38 (23 %) simultaneous pancreas-kidney transplant (SPK), 24 (15 %) pancreas after kidney transplant (PAK), 75 (46 %) pancreas transplant alone (PTA), and 28 (17 %) pancreas before kidney transplant (PBK). The overall surgical complication rate was 46.1 %, with highest (62.5 %) in PAK and lowest (32.0 %) in PTA, P = 0.008. The late complications included 32.7 % infection and 3.6 % malignancy. Overall rejection of pancreas graft was 24.8 % including 18.2 % acute and 9.7 % chronic rejection. Rejection was highest in PTA group (36.0 %) and lowest in PBK (3.6 %). There were 56 cases (33.9 %) with graft loss in total, with highest graft loss rate in PTA (38.7 %). The 1-year, 5-year and 10-year pancreas graft survivals for total patients were 98.0 %, 87.7 % and 70.9 % respectively.

CONCLUSIONS

Enteric drainage in pancreas transplant could be applied safely not only in SPK but also in other subgroups. Enteric drainage itself would not compromise the immunological and graft survival outcomes.

Donor-derived Cell-free DNA in Solid-organ Transplant Diagnostics: Indications, Limitations, and Future Directions

The last few years have seen an explosion in clinical research focusing on the use of donor-derived cell-free DNA (dd-cfDNA) in solid-organ transplants (SOT). Although most of the literature published so far focuses on kidney transplants, there are several recent as well as ongoing research studies on heart, lung, pancreas, and liver transplants. Though initially studied as a noninvasive means of identifying subclinical or acute rejection in SOT, it is rapidly becoming clear that instead of being a specific marker for allograft rejection, dd-cfDNA is more appropriately described as a marker of severe injury, although the most common cause of this injury is allograft rejection. Multiple studies in kidney transplants have shown that although sensitivity for the diagnosis of antibody-mediated rejection is excellent, it is less so for T-cell-mediated rejection. It is possible that combining dd-cfDNA with other novel urine- or blood-based biomarkers may increase the sensitivity for the diagnosis of rejection. Irrespective of the cause, though, elevated dd-cfDNA seems to portend adverse allograft prognosis and formation of de novo donor-specific antibody. Although current data do not lend themselves to a clear conclusion, ongoing studies may reveal the utility of serial surveillance for the management of SOT as following levels of dd-cfDNA over time may provide windows of opportunity to intervene early and before irreversible allograft injury. Finally, cost-effectiveness studies will be needed to guide the ideal incorporation of dd-cfDNA into routine clinical practice.

Transplant Options for Patients With Diabetes and Advanced Kidney Disease: A Review

Optimal glycemic control in kidney transplant recipients with diabetes is associated with improved morbidity and better patient and allograft survival. Transplant options for patients with diabetes requiring insulin therapy and chronic kidney disease who are suitable candidates for kidney transplantation should include consideration of β-cell replacement therapy: pancreas or islet transplantation. International variation related to national regulatory policies exists in offering one or both options to suitable candidates and is further affected by pancreas/islet allocation policies and transplant waiting list dynamics. The selection of appropriate candidates depends on patient age, coexistent morbidities, the timing of referral to the transplant center (predialysis versus on dialysis) and availability of living kidney donors. Therefore, early referral (estimated glomerular filtration rate < 30 mL/min/1.73 m²) is of the utmost importance to ensure adequate time for informed decision making and thorough pretransplant evaluation. Obesity, cardiovascular disease, peripheral vascular disease, smoking, and frailty are some of the conditions that need to be addressed before acceptance on the transplant list, and ideally before dialysis becoming imminent. This review offers insights into selection of pancreas/islet transplant candidates by transplant centers and an update on posttransplant outcomes, which may have practice implications for referring nephrologists.

Immunosuppression considerations in simultaneous organ transplant

Solid organ transplantation is a life-saving procedure for patients in the end stage of heart, lung, kidney, and liver failure. For patients with more than one failing organ, simultaneous organ transplantation has emerged as a viable treatment option. Immunosuppression strategies and outcomes for simultaneous organ transplant recipients have been reported, but often involve limited populations. Transplanting dual organs poses challenges in terms of balancing immunosuppression with immunologic risk and allograft damage from surgical complications. Furthermore, transplanting certain organs can impose considerations on the management of immunosuppression. For example, liver allografts may confer immunologic privilege and lower rates of rejection of other allografts. This review article evaluates immunosuppression strategies for simultaneous kidney-pancreas, liver-kidney, heart-kidney, heart-liver, heart-lung, lung-liver, and lung-kidney transplants. To date, no comprehensive review exists to address immunosuppressive strategies in simultaneous organ transplant populations. Our review summarizes the available literature and provides evidence-based recommendations regarding immunosuppression strategies in simultaneous organ transplant recipients.

Results after 13 years of kidney-pancreas transplantation in type 1 diabetic patients in Comunidad Valenciana

INTRODUCTION

Simultaneous pancreas-kidney (SPK) transplant is a proven option of treatment for patients with type 1 diabetes mellitus and related end-stage renal disease, who are candidates for kidney transplantation. The results from the beginning of SPK transplant program in Comunidad Valenciana are presented.

METHODS

Descriptive, retrospective, and single-center study of the pancreas transplant performed at the Hospital Universitari i Politècnic La Fe, from September 2002 to December 2015. Clinical variables from donors and recipients, peri-operative variables, patient survival, and pancreatic graft survival were collected.

RESULTS

Eighty-one patients with type 1 diabetes mellitus (48 males and 33 females, mean age 37.4±5.7 years, mean BMI 24.1±3.4kg/m2, mean duration of diabetes 25.5±6.5 years) received SPK transplantation. The overall patient survival at one, 3, and 5 years were 91,3, 91,3 and 89,5%, respectively. However, patient survival in the periods 2002-2008 and 2009-2015 were 88.2 and 93.6% at one year, 88.2 and 93.7% at 3 years, and 85.3 and 93.7% at 5 years, respectively (P=1). The overall pancreatic graft survival at one, 3, and 5 years were 75.2, 69.1 and 63.2%, respectively. On the other hand, pancreatic graft survival in the periods 2002-2008 and 2009-2015 were 67.5 and 80.6% at one year, 64.7 and 71.8% at 3 years, and 58.8% and 65.3% at 5 years, respectively (P=.0109). Postransplant complications were: graft rejection 8.6%, venous graft thrombosis 7.4%, graft pancreatitis 4.9%.

CONCLUSIONS

In 13-year's experience of SPK transplantation, patient and pancreatic graft survival and the rate of complications after pancreas transplantation were similar to those of other larger series. The medical-surgical team experience improves pancreatic graft survival without influencing patient survival.

Biomarker and surrogate development in vascularised composite allograft transplantation: Current progress and future challenges

Vascularised composite allograft (VCA) transplantation is now a feasible reconstructive option for patients who have suffered significant soft tissue injuries. However, despite numerous technical advances in the field over two decades, a number of challenges remain, not least the management of transplant rejection. Part of the difficulty faced by clinicians is the early recognition and prevention of acute rejection episodes. Whilst this is potentially easier in VCAs than solid organ transplants, due to their visible skin component, at present the only validated method for the diagnosis of acute rejection is histological examination of a tissue biopsy. The aim of this review article is to provide an evidence-based overview of progress in the field of VCA biomarker discovery, including immune cell subsets, immune cell effector pathways, and circulating markers of allograft damage, and to discuss future challenges in the field.

Molecular assessment of antibody-mediated rejection in human pancreas allograft biopsies

Pancreas transplant longevity is limited by immune rejection, which is diagnosed by graft biopsy using the Banff Classification. The histological criteria for antibody-mediated rejection (AMR) are poorly reproducible and inconsistently associated with outcome. We hypothesized that a 34-gene set associated with antibody-mediated rejection in other solid organ transplants could improve diagnosis in pancreas grafts. The AMR 34-gene set, comprising endothelial, natural killer cell and inflammatory genes, was quantified using the NanoString platform in 52 formalin-fixed, paraffin-embedded pancreas transplant biopsies from 41 patients: 15 with pure AMR or mixed rejection, 22 with T cell-mediated rejection/borderline and 15 without rejection. The AMR 34-gene set was significantly increased in pure AMR and mixed rejection (P = .001) vs no rejection. The gene set predicted histological AMR with an area under the receiver operating characteristic curve (ROC AUC) of 0.714 (P = .004). The AMR 34-gene set was the only biopsy feature significantly predictive of allograft failure in univariate analysis (P = .048). Adding gene expression to DSA and histology increased ROC AUC for the prediction of failure from 0.736 to 0.770, but this difference did not meet statistical significance. In conclusion, assessment of transcripts has the potential to improve diagnosis and outcome prediction in pancreas graft biopsies.

Pancreas transplants from small donors: are the outcomes acceptable? A retrospective study

Despite good organ quality, pancreata from extremely small pediatric donors (<30 kg) are generally avoided by many centers because of concerns of reduced islet cell mass and early technical failure. Therefore, we sought to compare the outcomes of small pancreas grafts (<30 kg) to those from higher weight donors from transplants performed between 1994 and 2015 (n = 1183). A total of 33 pancreata were from donors' ≤30 kg (3%), with a mean weight of 23.8 kg and mean age of 7.8 years. Patient survival was similar at 1, 5, and 10 years between recipients of ≤30 and >30 kg donors (≤30 kg: 96.8%, 86.8%, and 78.1% vs. >30 kg: 96.8%, 89.5%, and 79.1%, P = 0.5). Pancreas graft survival at 1, 5, and 10 years was also similar, ≤30 kg: 93.9%, 73.2%, and 61.0% vs. >30 kg: 87%, 73.3%, and 58.3% (P = 0.7). This graft survival pattern was also seen when comparing pancreata from ≤20 kg donors to those from >20 to 30 kg. Cause of graft loss, and metabolic and physiologic outcomes did not differ between the groups. After assessing the impact of donor weight as a continuous variable and calculating recipient-to-donor weight ratio (RDWR), we observed no effect of donor weight on patient and graft outcomes.

Alloimmunity in pancreas transplantation

PURPOSE OF REVIEW

Despite significant improvement in pancreas allograft survival, rejection continues to be a major clinical problem. This review will focus on emerging literature related to the impact of pretransplant and de-novo DSA (dnDSA) in pancreas transplant recipients, and the diagnosis and treatment of T-cell-medicated rejection (TCMR) and antibody-mediated rejection (ABMR) in this complex group of patients.

RECENT FINDINGS

Recent data suggest that pretransplant DSA and the emergence of dnDSA in pancreas transplant recipients are both associated with increased risk of ABMR. The pancreas allograft biopsy is essential for the specific diagnosis of TCMR and/or ABMR, distinguish rejection from other causes of graft dysfunction, and to guide-targeted therapy. This distinction is important especially in the setting of solitary pancreas transplants but also in simultaneous pancreas-kidney transplants where solid evidence has now emerged demonstrating discordant biopsy findings. Treatment of rejection in a functioning pancreas can prolong allograft survival.

SUMMARY

The accurate and timely diagnosis of active alloimmune destruction in pancreas transplant recipients is paramount to preserving graft function in the long term. This review will discuss new, rapidly evolving information that is valuable for the physician caring for these patients to achieve optimal immunological outcomes.

Hypertension, but not body mass index, is predictive of increased pancreatic lipid content and islet dysfunction

Pancreatic steatosis is thought to be a negative risk factor for pancreas transplant outcomes. Despite considering donor body mass index (BMI) and the visualization of intercalated fat as indicators of donor pancreas lipid content, transplant surgeons do not use a quantitative method to directly measure steatosis when deciding to transplant a pancreas. In this study, we used nondiabetic human pancreata donated for research to measure the pancreatic and islet-specific lipid content to determine which clinical markers correlate best with lipid content. Interestingly, we found that BMI and age correlate with increased pancreatic lipid content (Panc-LC) in men, but not women. Our findings further suggest that total Panc-LC correlates with an increase in islet lipid content for both men and women. We noted that pancreata donated from individuals with a history of hypertension have increased Panc-LC independent of donor BMI or sex. Moreover, we identify hypertension as a risk factor for reduced islet function after islet isolation. Together, our findings emphasize differences in pancreas graft quality related to pancreatic and islet lipid content, which may not be predicted by assessing BMI alone but may be influenced by a donor history of hypertension.

Polyomavirus and cytomegalovirus infections are risk factors for grafts loss in simultaneous pancreas and kidney transplant

BACKGROUND

Published literature on predictors of polyomavirus (BKV) and cytomegalovirus (CMV) infections in simultaneous pancreas and kidney (SPK) transplant and their impact on allograft outcomes remain sparse. We hypothesize that BKV and CMV viremia infections decrease allograft survival in SPK. Identifying modifiable predictors of BKV and CMV may help tailor immunosuppression and improve allograft survival.

METHODS

All SPK recipients at our institution between January 2000 and April 2016 were included (n = 757). Thirty-nine recipients had BKV only and 25 had CMV only, and infection occurred at median follow-up times of 217 and 163 days, respectively. Event density sampling was used to match recipients with BKV or CMV to up to 10 recipients without infection by age, sex, and HLA mismatch status, and these were followed for a median of 4.3 years after infection.

RESULTS

Older age (HR 1.49 for each decade; 95% CI: 0.95, 2.35; P = .083) and tacrolimus use (HR 20.6; 95% CI: 2.37, 179.53; P = .006) were associated with increased incidence of BKV, but not CMV, infection. Both BKV and CMV infections were associated with increased risk of allograft failure for both pancreas (BKV [HR 2.17; 95% CI 1.47, 3.208; P = .000], CMV [HR 1.7; 95% CI 1.077, 2.687; P = .023]) and kidney (BKV [HR 2.65; 95% CI 1.765, 3.984; P = .000], CMV [HR 2.07; 95% CI 1.295, 3.308; P = .002]).

CONCLUSION

Older age at time of transplant and tacrolimus may help predict BKV infection in SPK recipients.

Islet Transplantation Alone Versus Solitary Pancreas Transplantation: an Outcome-Driven Choice?

PURPOSE OF REVIEW

In patients with type 1 diabetes with extreme glycemic variability, the restoration of pancreas endocrine function is potentially and completely achieved with islets of Langerhans (tissue derived from whole organ) or pancreas (whole organ) transplantation. The aim of our review is to report on the latest studies and to highlight the benefits and risks of the two procedures, providing clearer, more selective, evidence-based clinical indications that also consider the impact on the degenerative complications of diabetes as a potential benefit.

RECENT FINDINGS

Clinical experience in this field has been dynamic over the last three decades, and has been characterized by the development of more standardized protocols and a clearer definition of clinical outcome. On the contrary, the recommendations thus far are not well delineated and tend to overlap, and the past ADA position statement for pancreas transplant alone has also been applied to islet transplant alone, without differentiation. Both outcome-driven and non-outcome-driven criteria are considered in the conclusions, in an attempt to streamline indications for islet-alone or pancreas-alone transplantation.

Graft dysfunction in simultaneous pancreas kidney transplantation (SPK): Results of concurrent kidney and pancreas allograft biopsies

Simultaneous pancreas and kidney transplants offer significant therapeutic advantages but present a diagnostic approach dilemma in the diagnosis of rejection. Because both organs are from the same donor, the kidney has been treated traditionally as the "sentinel" organ to biopsy, presumably representing the status of both allografts. Truly concurrent biopsy studies, however, are needed to confirm this hypothesis. We examined 101 concurrent biopsies from 70 patients with dysfunction in either or both organs. Results showed concurrent rejection in 23 of 57 (40%) of cases with rejection; 19 of 57 (33.5%) and 15 of 57 (26.5%) showed kidney or pancreas only rejection, respectively. The degree and type of rejection differed in the majority (13 of 23, 56.5%) of cases with concurrent rejection, with the pancreas more often showing higher rejection grade. Taking into account pancreas dysfunction, a positive kidney biopsy should correctly predict pancreas rejection in 86% of the instances. However, the lack of complete concordance between the 2 organs, the discrepancies in grade and type of rejection, and the tendency for higher rejection grades in concurrent or pancreas only rejections, all support the rationale for pancreas biopsies. The latter provide additional data on the overall status of the organ, as well as information on nonrejection-related pathologies.

Pancreas Transplantation: Indications, Techniques, and Outcomes

Pancreas transplantation treats insulin-dependent diabetes with or without concurrent end-stage renal disease. Pancreas transplantation increases survival versus no transplant, increases survival when performed as simultaneous pancreas-kidney versus deceased-donor kidney alone, and improves quality of life. Careful donor and recipient selection are paramount to good outcomes. Several technical variations exist for implantation: portal versus systemic vascular drainage and jejunal versus duodenal versus bladder exocrine drainage. Complications are most frequently technical in the first year and immunologic thereafter. Graft rejection is challenging to diagnose and is treated selectively. Islet cell transplantation currently has inferior outcomes to whole-organ pancreas transplantation.

Simultaneous pancreas-kidney transplantation. Experience of the Doce de Octubre Hospital

INTRODUCTION

Simultaneous pancreas-kidney transplantation (SPKT) constitutes the therapy of choice for diabetes type1 or type2 associated with end-stage renal disease, because is the only proven method to restore normo-glicemic control in the diabetic patient.

METHODS

Retrospective and descriptive study of a series of 175 patients who underwent SPKT from March 1995 to April 2016. We analyze donor and recipient characteristics, perioperative variables and immunosuppression, post-transplant morbi-mortality, patient and graft survival, and risk factors related with patient and graft survival.

RESULTS

Median age of the donors was 28years and mean age of recipients was 38.8±7.3years, being 103 males and 72 females. Enteric drainage of the exocrine pancreas was performed in 113 patients and bladder drainage in 62. Regarding post-transplant complications, the overall rate of infections was 70.3%; graft pancreatitis 26.3%; intraabdominal bleeding 17.7%; graft thrombosis 12.6%; and overall pancreas graft rejection 10.9%. The causes of mortality were mainly cardiovascular and infectious complications. Patient survival at 1, 3 and 5-year were 95.4%, 93% and 92.4%, respectively, and pancreas graft survival at 1, 3 and 5-year were 81.6%, 77.9% y 72.3%, respectively.

CONCLUSIONS

In our 20-year experience of simultaneous pancreas-kidney transplantation, the morbidity rate, and 5-year patient and pancreas graft survivals were similar to those previously reported from the international pancreas transplant registries.

Pancreas-After-Islet Transplantation in Nonuremic Type 1 Diabetes: A Strategy for Restoring Durable Insulin Independence

Islet transplantation offers a minimally invasive approach for β cell replacement in diabetic patients with hypoglycemic unawareness. Attempts at insulin independence may require multiple islet reinfusions from distinct donors, increasing the risk of allogeneic sensitization. Currently, solid organ pancreas transplant is the only remaining surgical option following failed islet transplantation in the United States; however, the immunologic impact of repeated exposure to donor antigens on subsequent pancreas transplantation is unclear. We describe a case series of seven patients undergoing solid organ pancreas transplant following islet graft failure with long-term follow-up of pancreatic graft survival and renal function. Despite highly variable panel reactive antibody levels prior to pancreas transplant (mean 27 ± 35%), all seven patients achieved stable and durable insulin independence with a mean follow-up of 6.7 years. Mean hemoglobin A1c values improved significantly from postislet, prepancreas levels (mean 8.1 ± 1.5%) to postpancreas levels (mean 5.3 ± 0.1%; p = 0.0022). Three patients experienced acute rejection episodes that were successfully managed with thymoglobulin and methylprednisolone, and none of these preuremic type 1 diabetic recipients developed stage 4 or 5 chronic kidney disease postoperatively. These results support pancreas-after-islet transplantation with aggressive immunosuppression and protocol biopsies as a viable strategy to restore insulin independence after islet graft failure.

Pancreas transplantation in older patients is safe, but patient selection is paramount

Pancreas transplant outcomes have progressively improved. Despite this, some centers have continued to employ historical age limits for pancreas transplant candidates. We sought to determine the importance of chronological age in determining patient and graft survival rates after pancreas transplantation. A single-center, retrospective study of adult, deceased donor simultaneous pancreas and kidney (SPK) and solitary pancreas transplants (SP, including pancreas transplant alone and pancreas after kidney transplants) in recipients ≥ 55 years (55 + ), occurring between July 1, 1999, and June 30, 2012, was performed. Seven-hundred and forty patients underwent pancreas transplantation, of which 28 patients were 55 + . Patient survival was comparable for younger and older pancreas transplant recipients. Both non-death-censored and death-censored pancreatic graft survival rates were similar in younger and in older patients. Patients aged 45-54 and those aged 55 +  had more frequent cardiovascular events than younger pancreas transplant recipients. There was no difference in renal graft survival for SPK patients when compared with diabetic kidney transplant alone recipients aged 55 years and older. Older pancreas transplant recipients had acceptable long-term patient and graft survival rates, although complications may occur. Chronological age alone should not exclude a patient for pancreas transplant candidacy.

Impact of graft implantation order on graft survival in simultaneous pancreas-kidney transplantation

The optimal order of revascularization for pancreas and kidney grafts in simultaneous pancreas-kidney transplantation has not been established. In this study, we investigate the influence of graft implantation order on graft survival in SPK. 12 700 transplantations from the Scientific Registry of Transplant Recipients were analyzed retrospectively. Graft implantation order was determined based on the reported ischemia times of pancreas and kidney grafts. Pancreas and kidney graft survivals were analyzed depending on graft implantation order at 3 months and 5 years using Kaplan-Meier plots. Significance was tested with log-rank test and Cox regression model. In 8454 transplantations, the pancreas was implanted first (PBK), and in 4246 transplantations, the kidney was implanted first (KBP). The proportion of lost pancreas grafts at 3 months was significantly lower in PBK (9.4% vs. 10.8%, P = 0.011). Increasing time lag (>2 h) between kidney and pancreas graft implantation in KBP accentuated the detrimental impact on pancreas graft survival (12.5% graft loss at 3 months, P = 0.001). Technical failure rates were reduced in PBK (5.6 vs. 6.9%, P = 0.005). Graft implantation order had no impact on kidney graft survival. In summary, although observed differences are small, pancreas graft implantation first increases short-term pancreas graft survival and reduces rates of technical failure.

Laparoscopic Biopsies in Pancreas Transplantation

As there is no precise laboratory test or imaging study for detection of pancreas allograft rejection, there is increasing interest in obtaining pancreas tissue for diagnosis. Pancreas allograft biopsies are most commonly performed percutaneously, transcystoscopically, or endoscopically, yet pancreas transplant surgeons often lack the skills to perform these types of biopsies. We have performed 160 laparoscopic pancreas biopsies in 95 patients. There were 146 simultaneous kidney-pancreas biopsies and 14 pancreas-only biopsies due to pancreas alone, kidney loss, or extraperitoneal kidney. Biopsies were performed for graft dysfunction (89) or per protocol (71). In 13 cases, an additional laparoscopic procedure was performed at the same operation. The pancreas diagnostic tissue yield was 91.2%; however, the pancreas could not be visualized in eight cases (5%) and in 6 cases the tissue sample was nondiagnostic (3.8%). The kidney tissue yield was 98.6%. There were four patients with intraoperative complications requiring laparotomy (2.5%) with two additional postoperative complications. Half of all these complications were kidney related. There were no episodes of pancreatic enzyme leak and there were no graft losses related to the procedure. We conclude that laparoscopic kidney and pancreas allograft biopsies can be safely performed with very high tissue yields.

Virtual HLA Crossmatching as a Means to Safely Expedite Transplantation of Imported Pancreata

BACKGROUND

Imported pancreata accumulate cold ischemia time (CIT), limiting utilization and worsening outcomes. Flow cytometric crossmatching (FXM) is a standard method to assess recipient and donor compatibility, but can prolong CIT. Single-antigen bead assays allow for detection of recipient donor-specific HLA antibodies, enabling prediction of compatibility through a "virtual crossmatch" (VXM). This study investigates the utility and outcomes of VXM after transplantation of imported pancreata.

METHODS

We retrospectively compared outcomes of 153 patients undergoing pancreas transplantation at our institution over a 3.5-year period.

RESULTS

Three patient groups were analyzed based on geographic source of the pancreas graft and the type of prospective crossmatch performed: (1) imported VXM-only, n = 39; (2) imported VXM + FXM, n = 12; and (3) local VXM + FXM, n = 102. There were no episodes of hyperacute rejection and 1 episode of early antibody-mediated rejection (<90 days) in the imported VXM group. Death-censored graft survival, patient survival, and rejection rates were comparable among the recipient groups. For pancreata imported from United Network of Organ Sharing regions 3 and 4, proceeding to surgery without an FXM reduced CIT by 5.1 hours (P < 0.001). The time from organ arrival at the hospital to operation start was significantly shorter in the VXM-only group compared with the VXM + FXM group (P < 0.001).

CONCLUSIONS

Virtual crossmatch helps minimize CIT without increasing rejection or adversely affecting graft survival, making it a viable method to increase pancreas graft utilization across distant organ sharing regions.

Antibody-mediated rejection across solid organ transplants: manifestations, mechanisms, and therapies

Solid organ transplantation is a curative therapy for hundreds of thousands of patients with end-stage organ failure. However, long-term outcomes have not improved, and nearly half of transplant recipients will lose their allografts by 10 years after transplant. One of the major challenges facing clinical transplantation is antibody-mediated rejection (AMR) caused by anti-donor HLA antibodies. AMR is highly associated with graft loss, but unfortunately there are few efficacious therapies to prevent and reverse AMR. This Review describes the clinical and histological manifestations of AMR, and discusses the immunopathological mechanisms contributing to antibody-mediated allograft injury as well as current and emerging therapies.

Antibody Subclass Repertoire and Graft Outcome Following Solid Organ Transplantation

Long-term outcomes in solid organ transplantation are constrained by the development of donor-specific alloantibodies (DSA) against human leukocyte antigen (HLA) and other targets, which elicit antibody-mediated rejection (ABMR). However, antibody-mediated graft injury represents a broad continuum, from extensive complement activation and tissue damage compromising the function of the transplanted organ, to histological manifestations of endothelial cell injury and mononuclear cell infiltration but without concurrent allograft dysfunction. In addition, while transplant recipients with DSA as a whole fare worse than those without, a substantial minority of patients with DSA do not experience poorer graft outcome. Taken together, these observations suggest that not all DSA are equally pathogenic. Antibody effector functions are controlled by a number of factors, including antibody concentration, antigen availability, and antibody isotype/subclass. Antibody isotype is specified by many integrated signals, including the antigen itself as well as from antigen-presenting cells or helper T cells. To date, a number of studies have described the repertoire of IgG subclasses directed against HLA in pretransplant patients and evaluated the clinical impact of different DSA IgG subclasses on allograft outcome. This review will summarize what is known about the repertoire of antibodies to HLA and non-HLA targets in transplantation, focusing on the distribution of IgG subclasses, as well as the general biology, etiology, and mechanisms of injury of different humoral factors.

Interpreting Anti-HLA Antibody Testing Data: A Practical Guide for Physicians

The development of sensitive methods for alloantibody detection has been a significant advance in clinical transplantation. However, the complexity of the data from solid phase and crossmatch assays has led to potential confusion about how to use the results for clinical decision making. The goal of this review is to provide a practical guide for transplant physicians for the interpretation of antibody data to supplement consultation with local tissue typing experts. Sources of variability in both the solid phase and crossmatch assay are discussed as are recent data regarding C1q binding antibodies and IgG subclass testing. Although definitive approaches to alloantibody testing are not possible with our current knowledge, we outline a pragmatic approach that we hope will enhance clinical management in this area.

Pancreas Transplantation in the Modern Era

The field of pancreas transplantation has evolved from an experimental procedure in the 1980s to become a routine transplant in the modern era. With short- and long-term outcomes continuing to improve and the significant mortality, quality-of-life, and end-organ disease benefits, pancreas transplantation should be offered to more patients. In this article, we review current indications, patient selection, surgical considerations, complications, and outcomes in the modern era of pancreas transplantation.

Practical Applications in Immunohistochemistry: Evaluation of Rejection and Infection in Organ Transplantation

CONTEXT

-Immunohistochemical analysis of tissue biopsy specimens is a crucial tool in diagnosis of both rejection and infection in patients with solid organ transplants. In the past 15 years, the concept of antibody-mediated rejection has been refined, and diagnostic criteria have been codified in renal, heart, pancreas, and lung allografts (with studies ongoing in liver, small intestine, and composite grafts), all of which include immunoanalysis for the complement split product C4d.

OBJECTIVES

-To review the general concepts of C4d biology and immunoanalysis, followed by organ-allograft-specific data, and interpretative nuances for kidney, pancreas, and heart, with discussion of early literature for lung and liver biopsies. Additionally, practical applications and limitations of immunostains for infectious organisms (Polyomavirus, Adenoviridae [adenovirus], and the herpes virus family, including Herpes simplex virus, Cytomegalovirus, Human herpes virus 8, and Epstein-Barr virus) are reviewed in the context of transplant recipients.

DATA SOURCES

-Our experience and published primary and review literature.

CONCLUSIONS

-Immunohistochemistry continues to have an important role in transplant pathology, most notably C4d staining in assessment of antibody-mediated rejection and assessment of viral pathogens in tissue. In all facets of transplant pathology, correlation of morphology with special studies and clinical data is critical, as is close communication with the transplant team.

Simultaneous pancreas and kidney transplantation: current trends and future directions

Purpose of review

Important trends are being observed in pancreas transplantation in the USA. We will describe recent trends in simultaneous pancreas kidney (SPK) transplantation related to immunosuppression, treatment of rejection, and transplantation for patients of advanced age and C-peptide positive diabetes.

Recent findings

Rates of pancreas transplantation have declined, despite improved pancreatic graft outcomes. Regarding immunosuppression, trends in SPK transplantation include T-cell depletion induction therapy, waning mammalian target of rapamycin inhibitor use and steroid use in greater than 50% of pancreas transplant recipients with few patients undergoing late steroid weaning. Rejection of the pancreas may be discordant with the kidney after SPK and there is a greater appreciation of antibody-mediated rejection of the pancreas allograft. De-novo donor-specific antibody without graft dysfunction remains an active area of study, and the treatment for this condition is unclear. SPKs are being performed with greater frequency in type 2 diabetes mellitus patients and in patients of advanced age, with exemplary results.

Summary

The current state of the art in SPK transplantation is yielding superb and improving results.

Diagnosis and Treatment of Pancreas Rejection

Despite significant improvement in pancreas allograft survival, rejection of the pancreas remains a major clinical problem. In addition to cellular rejection of the pancreas, antibody-mediated rejection of the pancreas is now a well-described entity. The 2011 Banff update established comprehensive guidelines for the diagnosis of acute and chronic AMR. The pancreas biopsy is critical in order to accurately diagnose and treat pancreas rejection. Other modes of monitoring pancreas rejection we feel are neither sensitive nor specific enough. In this review, we examine recent advances in the diagnosis and treatment of pancreas rejection as well as describe practical diagnostic and treatment algorithms.

What's new in clinical solid organ transplantation by 2013

Innovative and exciting advances in the clinical science in solid organ transplantation continuously realize as the results of studies, clinical trials, international conferences, consensus conferences, new technologies and discoveries. This review will address to the full spectrum of news in transplantation, that verified by 2013. The key areas covered are the transplantation activity, with particular regards to the donors, the news for solid organs such as kidney, pancreas, liver, heart and lung, the news in immunosuppressive therapies, the news in the field of tolerance and some of the main complications following transplantation as infections and cancers. The period of time covered by the study starts from the international meetings held in 2012, whose results were published in 2013, up to the 2013 meetings, conferences and consensus published in the first months of 2014. In particular for every organ, the trends in numbers and survival have been reviewed as well as the most relevant problems such as organ preservation, ischemia reperfusion injuries, and rejections with particular regards to the antibody mediated rejection that involves all solid organs. The new drugs and strategies applied in organ transplantation have been divided into new way of using old drugs or strategies and drugs new not yet on the market, but on phase Ito III of clinical studies and trials.

Diagnosis of early pancreas graft failure via antibody-mediated rejection: single-center experience with 256 pancreas transplantations

Early pancreas graft loss is usually attributed to technical failure while the possibility of antibody-mediated rejection (AMR) is generally overlooked. To investigate the role of AMR in early pancreas graft loss, we retrospectively assessed 256 patients with simultaneous pancreas-kidney transplantation (SPK) between 1985 and 2010 at our institute. We included 33 SPK patients who lost their pancreas graft <1 year after transplantation. AMR was diagnosed based on donor-specific antibodies, C4d and histology in 7 cases, 8 cases were suspicious for AMR and 18 pancreas graft losses were not due to AMR. Acute AMR occurred >1 month after transplantation in 6/7 cases, whereas all other causes typically led to loss <1 month after transplantation. Thrombotic lesions occurred equally among the 33 cases. In 12/18 concurrent kidney specimens, the diagnostic results paralleled those of the pancreas graft. All patients with acute AMR of the pancreas graft lost their renal grafts <1 year after transplantation. In the setting of a thrombotic event, histopathological analysis of early pancreas graft loss is advisable to rule out the possibility of AMR, particularly because a diagnosis of acute AMR has important consequences for renal graft outcomes.

Banff 2013 meeting report: inclusion of c4d-negative antibody-mediated rejection and antibody-associated arterial lesions

The 12th Banff Conference on Allograft Pathology was held in Comandatuba, Brazil, from August 19-23, 2013, and was preceded by a 2-day Latin American Symposium on Transplant Immunobiology and Immunopathology. The meeting was highlighted by the presentation of the findings of several working groups formed at the 2009 and 2011 Banff meetings to: (1) establish consensus criteria for diagnosing antibody-mediated rejection (ABMR) in the presence and absence of detectable C4d deposition; (2) develop consensus definitions and thresholds for glomerulitis (g score) and chronic glomerulopathy (cg score), associated with improved inter-observer agreement and correlation with clinical, molecular and serological data; (3) determine whether isolated lesions of intimal arteritis ("isolated v") represent acute rejection similar to intimal arteritis in the presence of tubulointerstitial inflammation; (4) compare different methodologies for evaluating interstitial fibrosis and for performing/evaluating implantation biopsies of renal allografts with regard to reproducibility and prediction of subsequent graft function; and (5) define clinically and prognostically significant morphologic criteria for subclassifying polyoma virus nephropathy. The key outcome of the 2013 conference is defining criteria for diagnosis of C4d-negative ABMR and respective modification of the Banff classification. In addition, three new Banff Working Groups were initiated.