Correction to: Identification of an intracellular metabolic signature impairing beta cell function in the rat beta cell line INS-1E and human islets.

As part of an institutional investigation by University of Bremen, the work carried out by Kathrin Maedler's laboratory has been reviewed.

The Incremental Cost of Incompatible Living Donor Kidney Transplantation: A National Cohort Analysis.

Incompatible living donor kidney transplantation (ILDKT) has been established as an effective option for end-stage renal disease patients with willing but HLA-incompatible living donors, reducing mortality and improving quality of life. Depending on antibody titer, ILDKT can require highly resource-intensive procedures, including intravenous immunoglobulin, plasma exchange, and/or cell-depleting antibody treatment, as well as protocol biopsies and donor-specific antibody testing. This study sought to compare the cost and Medicare reimbursement, exclusive of organ acquisition payment, for ILDKT (n = 926) with varying antibody titers to matched compatible transplants (n = 2762) performed between 2002 and 2011. Data were assembled from a national cohort study of ILDKT and a unique data set linking hospital cost accounting data and Medicare claims. ILDKT was more expensive than matched compatible transplantation, ranging from 20% higher adjusted costs for positive on Luminex assay but negative flow cytometric crossmatch, 26% higher for positive flow cytometric crossmatch but negative cytotoxic crossmatch, and 39% higher for positive cytotoxic crossmatch (p < 0.0001 for all). ILDKT was associated with longer median length of stay (12.9 vs. 7.8 days), higher Medicare payments ($91 330 vs. $63 782 p < 0.0001), and greater outlier payments. In conclusion, ILDKT increases the cost of and payments for kidney transplantation.

Amyloid formation in human islets is enhanced by heparin and inhibited by heparinase.

Islet transplantation is a promising therapy for patients with diabetes, but its long-term success is limited by many factors, including the formation of islet amyloid deposits. Heparin is employed in clinical islet transplantation to reduce clotting but also promotes fibrillization of amyloidogenic proteins. We hypothesized that heparin treatment of islets during pre-transplant culture may enhance amyloid formation leading to beta cell loss and graft dysfunction. Heparin promoted the fibrillization of human islet amyloid polypeptide (IAPP) and enhanced its toxicity to INS-1 beta cells. Heparin increased amyloid deposition in cultured human islets, but surprisingly decreased islet cell apoptosis. Treatment of human islets with heparin prior to transplantation increased the likelihood of graft failure. Removal of islet heparan sulfate glycosaminoglycans, which localize with islet amyloid deposits in type 2 diabetes, by heparinase treatment decreased amyloid deposition and protected against islet cell death. These findings raise the possibility that pretransplant treatment of human islets with heparin could potentiate IAPP aggregation and amyloid formation and may be detrimental to subsequent graft function.

A novel and personalized rehabilitation program for obese kidney transplant recipients.

INTRODUCTION: Physical rehabilitation programs for kidney transplant recipients are not routinely personalized to patients' physical and emotional health, which could result in a potentially limited health impact, shorter-term participation, and an overall low success rate. MATERIALS AND METHODS: We conducted an internal review board-approved randomized prospective study involving a 12-month supervised multidisciplinary rehabilitation program (GH method) initiated after kidney transplantation in obese recipients (body mass index >30). The new method incorporates 3 major components: physical exercise, behavioral interventions, and nutritional guidance. We compared 9 patients who underwent supervised rehabilitation with 8 patients who underwent standard care. Patients were followed up after the start of the intervention, and multiple assessments were performed. RESULTS: The adherence to training and follow-up was 100% in the intervention group, compared with 25% at 12 months in the control group. There was a trend for a higher glomerular filtration rate in the intervention group compared with the control group (55.5 ± 18.6 mL/min/1.73 m(2) vs 38.8 ± 18.9 mL/min/1.73 m(2), P = .06). The quality of life (SF-36) mean score improved more in the intervention group compared with the control group (583 ± 13 vs 436 ± 22, P = .008). There was a significantly higher employment rate in the intervention group, 77.7% at 12 months compared with 12.5% in the control group (P = .02). CONCLUSIONS: Our preliminary results suggest that this comprehensive approach to physical rehabilitation can improve adherence, kidney function, quality of life, and employment rate for obese patients after kidney transplantation.

Quantifying the risk of incompatible kidney transplantation: a multicenter study.

Incompatible live donor kidney transplantation (ILDKT) offers a survival advantage over dialysis to patients with anti-HLA donor-specific antibody (DSA). Program-specific reports (PSRs) fail to account for ILDKT, placing this practice at regulatory risk. We collected DSA data, categorized as positive Luminex, negative flow crossmatch (PLNF) (n = 185), positive flow, negative cytotoxic crossmatch (PFNC) (n = 536) or positive cytotoxic crossmatch (PCC) (n = 304), from 22 centers. We tested associations between DSA, graft loss and mortality after adjusting for PSR model factors, using 9669 compatible patients as a comparison. PLNF patients had similar graft loss; however, PFNC (adjusted hazard ratio [aHR] = 1.64, 95% confidence interval [CI]: 1.15-2.23, p = 0.007) and PCC (aHR = 5.01, 95% CI: 3.71-6.77, p < 0.001) were associated with increased graft loss in the first year. PLNF patients had similar mortality; however, PFNC (aHR = 2.04; 95% CI: 1.28-3.26; p = 0.003) and PCC (aHR = 4.59; 95% CI: 2.98-7.07; p < 0.001) were associated with increased mortality. We simulated Centers for Medicare & Medicaid Services flagging to examine ILDKT's effect on the risk of being flagged. Compared to equal-quality centers performing no ILDKT, centers performing 5%, 10% or 20% PFNC had a 1.19-, 1.33- and 1.73-fold higher odds of being flagged. Centers performing 5%, 10% or 20% PCC had a 2.22-, 4.09- and 10.72-fold higher odds. Failure to account for ILDKT's increased risk places centers providing this life-saving treatment in jeopardy of regulatory intervention.

High rate of unemployment after kidney transplantation: analysis of the United network for organ sharing database.

INTRODUCTION: Despite an increased quality of life after transplant, in the United States, recipients participate less in employment compared to the general population. Employment after kidney transplantation is an important marker of clinically significant individual health recovery. Furthermore, it has been shown that employment status in the post-transplant period has a strong and independent association with patient and graft survival. MATERIALS AND METHODS: Using the United Network for Organ Sharing (UNOS) database, we identified all adults (between 18 and 64 years of age) who underwent kidney transplantation between 2004 and 2011. Patients with a stable renal allograft function and with full 1-, 3-, and 5-year follow-up were included. For recipients of multiple transplants, the most recent transplant was considered the target transplant. The data collected included employment rate after kidney transplantation in recipients employed and unemployed before transplant. The employment data were stratified for insurance payer (private, Medicaid, and Medicare). The results of categorical variables are reported as percentages. Comparisons between groups for categorical data were performed using the χ(2) test with Yates continuity correction or Fisher test when appropriate. RESULTS: The UNOS database available for this study included a total of 100,521 patients. The employment rate at the time of transplant was 23.1% (n = 23,225) under private insurance and 10% (n = 10,032) under public insurance (Medicaid and Medicare, P < .01, compared to private insurance). Over a total of 29,809 recipients analyzed, alive and with stable renal allograft function who were working at time of transplantation, the employment rate was 47% (n = 14,010), 44% (n = 13,115), and 43% (n = 12,817) at 1, 3, and 5 years after transplant under private insurance and 16% (n = 4769), 14% (n = 4173), and 12% (n = 3567), respectively, under public insurance (P < .01, compared to private insurance). Over a total of 46,363 recipients alive and with stable renal function who were not working at time of transplant, the employment rate was 5.3% (n = 2457), 5.6% (n = 2596), and 6.2% (n = 2874) at 1, 3, and 5 years after transplant under private insurance and 6.5% (n = 3013), 7.8% (n = 3616), and 7.5% (n = 3477), respectively, under public insurance (P < .01, compared to private insurance). CONCLUSION: The employment rates at the time of transplant in the United States are generally low, although privately insured patients are significantly more likely than patient with public insurance to have employment. Only a portion of these patients returns to work after transplantation. For the patients unemployed at the time of transplantation, the chance to find a job afterward is quite low even in privately insured patients. A concerted effort should be made by the transplant community to improve the ability of successful kidney transplant recipients to return to work or find a new employment. It had been shown that employment status in the post-transplant period has a strong and independent association with the graft and recipient survival.

The application of indocyanine green to evaluate duodenal perfusion in pancreas transplantation.

In cases of suspected duodenal ischemia during pancreas transplantation, surgical decisions severely affect the outcome of the patient and the graft. The use of a nontoxic intravenous tracer, indocyanine green, allows the surgeon to evaluate the perfusion of tissues within seconds of injection. Its application to pancreas transplantation has not been reported previously.

Alginate microencapsulation of human islets does not increase susceptibility to acute hypoxia.

Islet transplantation in diabetes is hampered by the need of life-long immunosuppression. Encapsulation provides partial immunoprotection but could possibly limit oxygen supply, a factor that may enhance hypoxia-induced beta cell death in the early posttransplantation period. Here we tested susceptibility of alginate microencapsulated human islets to experimental hypoxia (0.1-0.3% O2 for 8 h, followed by reoxygenation) on viability and functional parameters. Hypoxia reduced viability as measured by MTT by 33.8 ± 3.5% in encapsulated and 42.9 ± 5.2% in nonencapsulated islets (P < 0.2). Nonencapsulated islets released 37.7% (median) more HMGB1 compared to encapsulated islets after hypoxic culture conditions (P < 0.001). Glucose-induced insulin release was marginally affected by hypoxia. Basal oxygen consumption was equally reduced in encapsulated and nonencapsulated islets, by 22.0 ± 6.1% versus 24.8 ± 5.7%. Among 27 tested cytokines/chemokines, hypoxia increased the secretion of IL-6 and IL-8/CXCL8 in both groups of islets, whereas an increase of MCP-1/CCL2 was seen only with nonencapsulated islets. Conclusion. Alginate microencapsulation of human islets does not increase susceptibility to acute hypoxia. This is a positive finding in relation to potential use of encapsulation for islet transplantation.

Cerebellar abscess caused by Listeria monocytogenes in a liver transplant patient.

Brain abscesses are a rare but serious complication and have been documented in transplant recipients. Aspergillus is by far the most frequent etiology of post-transplant brain abscesses. Bacteria, apart from Nocardia, have a low association with brain abscesses in transplant recipients. We report herein the case of a 52-year-old man who had undergone orthotopic liver transplantation (OLT) for end-stage liver disease and hepatocellular carcinoma secondary to chronic hepatitis, and who developed a cerebellar abscess (CA) from Listeria monocytogenes. Three months after transplantation, he presented with a 1-week history of headache and vomiting. Computed tomography scan of the brain revealed a space-occupying lesion in the right cerebellum, which was further confirmed by magnetic resonance imaging. Emergency surgery was planned because of pressure effect on the surrounding structures. The patient recovered smoothly from the surgery. To our knowledge, no reports of Listeria CA following OLT have been published in the English literature. This case shows that, although extremely rare, L. monocytogenes may cause CA in liver transplant recipients, and clinicians should be aware of this, so that prompt diagnosis and treatment can be instituted before serious brain damage can occur.

Unconventional extrahepatic neovascularization after transplant hepatic artery thrombosis: a case report.

Liver neovascularization preserves hepatic function and improves survival in the setting of post-transplant hepatic artery thrombosis (HAT). In this report, we have presented a unique case of a neovascularized liver after subclinical HAT in a 46-year-old liver transplant patient in whom a collateral supply was recruited from three unconventional sources: The right colic, right intercostal, and right inferior adrenal arteries. We propose systematic angiographic evaluation of all potential sources of collateral vessel formation for patients with HAT to accurately assess patient risk and determine the need for further intervention or revascularization.

Systematic analysis of donor and isolation factor's impact on human islet yield and size distribution.

Islet transplantation is a promising therapy for T1DM. Key factors influencing islet yield have been identified with conflicting results. In this study, we analyzed 276 isolations to identify variables for islet yield and, additionally, islet size and size distribution. Pearson correlation analyses demonstrated that BMI had a positive correlation with pancreas size, actual islet count (AIC), and islet equivalent (IEQ)/g (all p ≤ 0.009), while CIT had a negative correlation with AIC and IEQ/g (all p ≤ 0.003). In mixed linear regression, BMI also had a positive correlation with islet size but only for shorter digestion times (≤15 min); there was no association between BMI and islet size for longer digestion times (>15 min). CIT was not associated with islet size. Donor age, sex, and preservation solutions were shown to have no correlation with islet yields or size distribution. Pancreas size had a positive correlation with AIC and a negative association with IEQ/g; it also had positive association with islet size but only for females, not males. Overdigestion was positively associated with islet counts; however, there was also a greater proportion of smaller islets when digestion rate was >74% (p = 0.005). Of the three collagenases analyzed, Sigma V had the lowest digestion rate (mean = 65%), approximately 5% or 10% lower than Roche Liberase HI (p = 0.04) and Serva NB1 (p = 0.0003), respectively; however, the Sigma V group showed better islet size preservation. Yet, the enzymes resulted in similar IEQ/g digested tissue. Of the isolated islets, 70.2% were smaller than 150 µm and contributed only 20.4% to the total IEQ, while 7.4% of the islets were larger than 250 µm but contributed 42.4% to the total IEQ. In summary, BMI, pancreas size, and CIT are useful variables for predicting islet yield, but selection of enzyme and balancing digestion time and rate are also important.

Oestrogens improve human pancreatic islet transplantation in a mouse model of insulin deficient diabetes.

AIMS/HYPOTHESIS: Pancreatic islet transplantation (PIT) offers a physiological treatment for type 1 diabetes, but the failure of islet engraftment hinders its application. The female hormone 17ß-oestradiol (E2) favours islet survival and stimulates angiogenesis, raising the possibility that E2 may enhance islet engraftment following PIT. METHODS: To explore this hypothesis, we used an insulin-deficient model with xenotransplantation of a marginal dose of human islets in nude mice rendered diabetic with streptozotocin. This was followed by 4 weeks of treatment with vehicle, E2, the non-feminising oestrogen 17α-oestradiol (17α-E2), the oestrogen receptor (ER) α agonist propyl-pyrazole-triol (PPT), the ERß agonist diarylpropionitrile (DPN) or the G protein-coupled oestrogen receptor (GPER) agonist G1. RESULTS: Treatment with E2, 17α-E2, PPT, DPN or G1 acutely improved blood glucose and eventually promoted islet engraftment, thus reversing diabetes. The effects of E2 were retained in the presence of immunosuppression and persisted after discontinuation of E2 treatment. E2 produced an acute decrease in graft hypoxic damage and suppressed beta cell apoptosis. E2 also acutely suppressed hyperglucagonaemia without altering insulin secretion, leading to normalisation of blood glucose. CONCLUSIONS/INTERPRETATION: During PIT, E2 synergistic actions contribute to enhancing human islet-graft survival, revascularisation and functional mass. This study identifies E2 as a short-term treatment to improve PIT.

The use of bortezomib as a rescue treatment for acute antibody-mediated rejection: report of three cases and review of literature.

Antibody-mediated rejection (AMR) typically occurs early after transplantation in approximately 5%-7% of recipients. The literature reports suggest that 12%-37% of kidney transplant recipients with acute AMR do not respond to treatment and eventually lose their grafts. The proteasome inhibitor bortezomib is currently approved by the Food and Drug Administration for the treatment of multiple myeloma. It has been demonstrated both in vitro and in vivo to possess apoptotic properties against mature plasma cells. Herein we have described a series of 3 patients with positive cross-matches who developed early AMR after kidney transplantation. Bortezomib rescue treatment was administered after the patients failed to respond to plasmapheresis/intravenous immunoglobulin and splenectomy. All 3 patients responded with full, durable recovery of renal function. In conclusion, bortezomib is useful to treat refractory AMR after kidney transplantation.

TCF7L2 promotes beta cell regeneration in human and mouse pancreas.

AIMS/HYPOTHESIS: Diabetes is characterised by loss and dysfunction of the beta cell. A major goal of diabetes therapy is to promote the formation of new beta cells. Polymorphisms of T cell factor 7-like 2 (TCF7L2) are associated with type 2 diabetes, negatively regulating beta cell survival and function. Here, we provide evidence for a role of TCF7L2 in beta cell proliferation and regeneration. METHODS: Pancreatic sections from three mouse models (high-fat diet, exendin-4 and streptozotocin-treated mice) and from healthy individuals and patients with type 2 diabetes were used to investigate the association of beta cell regeneration and TCF7L2 levels. To analyse a direct effect of TCF7L2 on duct cell to beta cell conversion, TCF7L2 was overexpressed in isolated exocrine cells. RESULTS: TCF7L2 levels correlated with beta cell compensation during high-fat diet feeding. TCF7L2 was increased together with pancreatic duct cell proliferation and differentiation. Small islet-like cell clusters (ICCs) that contained TCF7L2 originated in the vicinity of the ductal epithelium. In human isolated exocrine tissue, TCF7L2 overexpression induced proliferation of pancreatic duct cells and ICC formation next to duct cells, an effect dependent on the JAK2/STAT3 pathway. CONCLUSIONS/INTERPRETATION: The present study demonstrates that TCF7L2 overexpression fosters beta cell regeneration. Our findings imply correlation of TCF7L2 levels and new beta cell formation.

The role of splenectomy in the setting of refractory humoral rejection after kidney transplantation.

Living donor kidney transplantation remains the best option for presensitized recipients to avoid excessive time on the waiting list. However, the possibility for a positive crossmatch with a potential living donor is high. A desensitization protocol may be required to avoid antibody-mediated rejection (AMR). Current protocols are not always effective to prevent AMR and in some cases fail to convert subjects to a negative crossmatch before transplantation. From March 2006 to January 2011, the 11 presensitized patients who displayed AMR after living donor kidney transplantation underwent splenectomy as a rescue procedure due to failure of standard rejection treatments. Splenectomy was considered to be effective in six recipients who normalized their renal function without the need for other immunomodulating therapy. Our analysis suggested that splenectomy can be successfully performed alone or in association with other treatments like bortezomib or rituximab to overcome severe AMR.

A multicenter study of histoplasmosis and blastomycosis after solid organ transplantation.

AIM: A review of the clinical presentation, diagnosis, treatment and outcomes of 30 solid organ transplant recipients (SOTRs) with histoplasmosis or blastomycosis from 3 Midwestern academic medical centers. BACKGROUND: The endemic fungal pathogens, Histoplasma capsulatum and Blastomyces dermatitidis, may cause severe infection in SOTRs. In this report, we describe the clinical presentation, diagnosis, treatment, and outcomes of these endemic fungal infections (EFIs) among SOTRs at 3 academic transplant centers. METHODS: A retrospective review was conducted of SOTRs with histoplasmosis or blastomycosis from 3 Midwestern medical centers in the United States. Data collected included demographics, immunosuppression, clinical presentation, method of diagnosis, antifungal treatment, response to therapy, and patient and graft survival. RESULTS: Between 1996 and 2008, 30 transplant recipients with histoplasmosis or blastomycosis were identified, giving a cumulative incidence of infection of 0.50% (30/5989); 73% of the study patients were renal transplant recipients, and the median time to disease onset after transplantation was 10.5 months. The lungs were the most common site of infection (83%), and 60% had disseminated disease. Urine antigen testing was positive in all patients in whom it was performed (23/23). Initial antifungal therapy consisted of amphotericin B in 70%, and 87% received azoles, typically itraconazole (83%). Two patients developed relapsed infection and 7 patients had graft failure after EFI. Overall mortality was 30%, with an attributable mortality of 13%. CONCLUSIONS: As in several previous single-center studies, the incidence of post-transplant histoplasmosis and blastomycosis was <1%, but often resulted in disseminated infection. In this cohort, EFI was associated with a high rate of allograft loss and overall mortality.

TOSO promotes ß-cell proliferation and protects from apoptosis.

Decreased ß-cell mass reflects a shift from quiescence/proliferation into apoptosis, it plays a crucial role in the pathophysiology of diabetes. A major attempt to restore ß-cell mass and normoglycemia is to improve ß-cell survival. Here we show that switching off the Fas pathway using Fas apoptotic inhibitory protein (Faim/TOSO), which regulates apoptosis upstream of caspase 8, blocked ß-cell apoptosis and increased proliferation in human islets. TOSO was clearly expressed in pancreatic ß-cells and down-regulated in T2DM. TOSO expression correlated with ß-cell turnover; at conditions of improved survival, TOSO was induced. In contrast, TOSO downregulation induced ß-cell apoptosis. Although TOSO overexpression resulted in a 3-fold induction of proliferation, proliferating ß-cells showed a very limited capacity to undergo multiple rounds of replication. Our data suggest that TOSO is an important regulator of ß-cell turnover and switches ß-cell apoptosis into proliferation.

Identification of an intracellular metabolic signature impairing beta cell function in the rat beta cell line INS-1E and human islets.

AIMS/HYPOTHESIS: Chronic hyperglycaemia promotes the progressive failure of pancreatic beta cells in patients with type 2 diabetes mellitus, a clinically highly relevant phenomenon known as glucotoxicity. The intracellular metabolic consequences of a chronically high availability of glucose in beta cells are, as yet, poorly understood in its full complexity. METHODS: An unbiased metabolite profiling analysis (GC-time-of-flight-MS) was used to identify the time course of core metabolite patterns in rat beta cell line INS-1E during exposure to high glucose concentrations and its relation to insulin expression. RESULTS: We report here that pentose phosphate pathway (PPP) metabolites accumulate remarkably during chronic but not acute glucose treatment, indicating altered processing of glucose through the pentose phosphate pathway. Subsequent functional studies in INS-1E cells and human islets revealed that a disturbance in this pathway contributes to decreases in insulin gene expression and a lack of glucose-stimulated insulin secretion. These effects were found to depend on the activation of extracellular-regulated-kinase (ERK1/2). Long-term inhibition of 6-phosphogluconic acid dehydrogenase resulted in accumulation of PPP metabolites, induced ERK1/2 activation independently of high glucose and impaired beta cell function. In turn, inhibition of ERK1/2 overstimulation during chronic glucose exposure partly inhibited metabolite accumulation and restored beta cell function. CONCLUSIONS/INTERPRETATION: Based on unbiased metabolite analyses, the data presented here provide novel targets, namely the inhibition of PPP metabolite accumulation towards the therapeutic goal to preserve and potentially improve beta cell function in diabetes.