Samstag, 03.10.2020

14:00 - 15:30

Poster DGfN 2020

Transplantation 3 (P221 - P228; LA47)

Osteoprotegerin Is an Independent Risk Factor Predicting Death in Stable Renal Transplant Recipients

S. Zeng, T. Slowinski, A. Hasan, C. Chu, Y. Xiong, S. Elitok, B. K. Krämer, B. Hocher; Berlin, Potsdam, Mannheim

Objective: Vascular calci?cation is common in chronic kidney disease and is associated with signi?cant cardiovascular morbidity and mortality. One of the important factors regulating vascular calci?cation is osteoprotegerin (OPG). There are, however, limited to the impact of OPG on all-cause mortality and graft loss in kidney transplant recipients so far. Given its impact on vascular calcification, the aim of our study is to analyze whether OPG is a risk factor of all-cause mortality and graft loss in 600 stable kidney transplant recipients.
Method: 600 stable renal transplant recipients (367women, 233 men) were followed for all-cause mortality and graft loss for 3 years. Blood and urine samples for analysis and clinical data were collected at study entry. We performed the Kaplan-Meier survival analysis and Cox regression models considering confounding factors such as age, eGFR, cold ischemia time, HbA1c, phosphorus, calcium, and albumin.
Results: Sixty-five patients died and thirty-eight patients had graft loss during the observation period. The OPG baseline concentrations had no effect on graft loss whereas the Kaplan-Meier survival curve showed that baseline plasma OPG concentrations were associated with all-cause mortality in stable kidney transplant recipients (p<0.0001, log-rank test). After multiple Cox regression analysis assisting for age, eGFR, cold ischemia time, HbA1c, phosphorus, calcium, and albumin, plasma levels of OPG remained an independent predictor of all-cause mortality (HR, 1.181; 95%CI 1.035-1.347; p=0.014).
Conclusion: Baseline plasma OPG is an independent risk factor for all-cause mortality but not graft loss in patients after kidney transplantation.

Improved glucose metabolism in patients on kidney transplant waiting list after recommendation for lifestyle intervention - a 4-yr. follow-up

M. Guthoff, D. Vosseler, S. Nadalin, A. Königsrainer, A. L. Birkenfeld, N. Heyne; Tübingen, Dresden

Objective: Diabetes mellitus (DM), whether pre-existing or developing after kidney transplantation (PTDM), significantly impairs patient and allograft outcome. Prediabetes prior to transplantation has been shown a key risk factor for PTDM. We have previously shown that 33% of patients on kidney transplant waiting list have unknown disturbances in glucose metabolism. Here we present 4 yr. follow-up data of these patients, after having recommended lifestyle intervention.
Method: Glucose metabolism was assessed in n = 138 patients on the waiting list in 2013. Patients with newly diagnosed prediabetes or diabetes were recommended to perform lifestyle intervention (increase in physical activity and dietary modifications). In 2017, a follow-up investigation of patients on the active waiting list at the Tübingen Collaborative Transplant Center was performed (n = 134). On both occasions, glucose metabolism was assessed via OGTT and HbA1c and patients were classed into normal glucose tolerance (NGT), prediabetes or diabetes.
Results: Of the patients on the waiting list in 2013, n = 75 had received a kidney allograft until 2017. 22 patients had to be removed due to medical conditions, 91 patients were new entries on the waiting list. In total, n = 41 patients have remained on the waiting list since 2013 and follow-up data were available. Of those with diabetes or prediabetes, 39% were able to improve glucose metabolism after lifestyle intervention. In total, 53% of all patients remained stable, whereas in 12%, glucose metabolism worsened.
Conclusion: Lifestyle intervention is a powerful tool to improve glucose metabolism, also in dialysis patients on kidney transplant waiting list, even outside a structured lifestyle intervention programme. The time on the waiting list is not just passive waiting time but can successfully be used to improve settings for a future transplantation.

Renal Transplantation in Patients with Polycystic Kidney Disease: Risks and Benefits – Multivariate Analysis and Case Control Study

F. Bachmann, L. d`Anjou, J. Klotsche, M. Naik, L. Liefeldt, K. Budde, F. Friedersdorff, R. Peters, J. Waiser; Berlin

Objective: Autosomal dominant polycystic kidney disease (ADPKD) is the most frequent hereditary disease causing end stage renal failure. Clinically, severe cystic infections often cause hospitalization and thus may limit patient or graft survival. Here, we analyzed the long-term risk factors for death, graft failure and urinary tract infection (UTI) in patients with ADPKD following renal transplantation and compared this group to a matched control group.
Method: We identified 193 patients with a diagnosis of ADPKD, who had received a renal transplant at our center between 01.01.2000 and 01.11.2017. Using multivariate analysis, we identified risk factors for death, graft failure and UTIs leading to inpatient treatment. For the matched-pair study, ADPKD patients were matched with control patients with respect to age at transplantation, recipient gender, date of transplantation, donor type and rejection episodes.
Results: The median observation time was 72 months (IQR: 38-118). Among the ADPKD group 33 (17%) patients died, in 42 (22%) patients graft failure occurred, and 86 (45%) patients experienced UTI or urosepsis causing hospitalization. Multivariate analysis revealed recipient age, recipient gender, donor type and rejection episodes as significant (p<0.01) risk factors for UTI / urosepsis. Matched-pair analysis showed that patient survival (83% vs. 77%, p=0.16) and graft survival (78% vs. 70%, p=0.08) were not different between groups, whereas the prevalence (45% vs. 32% of patients, p=0.008) and number (1.19 vs. 0.69 per patient, p<0.001) of UTIs / urosepsis was higher in ADPKD patients as compared to controls.
Conclusion: A diagnosis of ADPKD is a significant risk factor for urosepsis / severe UTI leading to hospitalization. Nevertheless, we observed no significant difference in patient and graft survival between patients with ADPKD as compared to patients with other underlying renal diseases. Recipient age, female gender, rejection episodes and deceased donor type significantly increased the risk of UTI / urosepsis in ADPKD patients. The question, whether or not uni- or bilateral nephrectomy should be performed, needs to be evaluated further.

Retrospektive Langzeitanalyse von Hospitalisierungsraten und deren Hauptdiagnosen bei Nierentransplantation

W. Düttmann, B. Zukunft, P. Glander, P. Bach, F. Halleck, M. Choi, F. Bachmann, M. Mayrdorfer, K. Budde, M. Naik; Berlin

Hintergrund: Die Hospitalisierungsrate von Patienten nach Nierentransplantation (NTx) ist hoch und die Hauptdiagnosen stationärer Aufnahmen sind vielgestaltig. Genaue Informationen dazu sind lückenhaft.
Methode: In einer retrospektiven und monozentrischen Analyse werteten wir DRG-Daten von 1.526 erwachsenen NTx Patienten vom 01.01.2009 bis 31.12.2018, also über 10 Jahre, aus.
Ergebnisse: Pro Jahr erfolgten durchschnittlich 746±58 Patienten Hospitalisierungen.


Der Anteil an Patienten, der initial über die Rettungsstelle versorgt werden musste, lag durchschnittlich bei 47,5%. Die gesamte Hospitalisierungsrate (HR) betrug 0.71±0.09 pro Patient und Jahr. Bei Patienten, die in den Jahren 2009 (n=82) und 2010 (n=105) nierentransplantiert wurden, also die längsten Beobachtungszeiträume aufwiesen, war die HR in den ersten zwei Jahren nach Transplantation am höchsten (1,38-1,7).


Im dritten und vierten Jahr nach Transplantation war die HR niedriger (0,48-0,7). Ab dem fünften Jahr bis Beobachtungsende lag die HR stabil bei etwa 0,26-0,49. Die HR ab dem 5. Jahr war signifikant niedriger im Vergleich zur HR innerhalb der ersten beiden Jahre nach Nierentransplantation.
Die häufigsten kodierten Hauptdiagnosen, beispielhaft dargestellt anhand zweier Jahre, gestalten sich wie folgt: Die Ursachen lassen sich zuordnen als: renal (akutes Nierenversagen/Rejektion/Verdacht auf Rejektion) (2015: 26,43%; 2016: 27,73%), infektiologisch (2015: 18,86%; 2016: 15,41 %), kardiologisch (2015: 7.36%, 2016: 6.59%) und gastroenterologisch (2015: 6.98%, 2016: 7.84%). Im Jahr 2015 wurden insgesamt 362 verschiedene Hauptdiagnosen kodiert und im Jahr 2016 waren es 349 verschiedene Hauptdiagnosen.
Zusammenfassung: Die Hospitalisierungen pro Jahr von Patienten nach NTx waren an unserem Zentrum auf hohem Niveau stabil. In den Jahren 2009 und 2010 transplantierte Patienten hatten die höchsten HR in den ersten zwei Jahren nach der Nierentransplantation. Die Hauptdiagnosen sind insgesamt vielseitig. Meist lagen renale Diagnosen vor (AKI/Rejektion/Verdacht auf Rejektion), gefolgt von infektiologischen, kardiologischen und gastroenterologische Aufnahmegründen. Der Anteil per Notfalleinweisung versorgter NTx betrug 47,5%.

Molecular and cellular mechanisms of Lipocalin-2 mediated renoprotection in kidney transplantation

A. M. Pfefferkorn, S. Sarfraz, A. Kusch, D. Dragun, H. G. Schwelberger, J. Pratschke, I. M. Sauer, F. Aigner, M. I. Ashraf; Berlin, Innsbruck/A, Graz/A

Objective: Lipocalin-2 (Lcn2) is distinctly upregulated in kidney transplants and serves as an early marker of AKI, DGF and acute rejection. However, the functional role and mechanisms underlying Lcn2 upregulation remain largely unknown. Using a mouse model of kidney transplantation we recently demonstrated a renoprotective role of recombinant Lcn2:Siderophore:Fe (rLcn2). However, the molecular and cellular events underlying the renoprotective effects of rLcn2 in kidney allografts remain unclear. Elucidating these events forms the primary focus of the current study.
Method: Kidneys were transplanted from Balb/c to C57Bl/6 mice (± rLcn2, 250mg/kg). A detailed immunophenotyping of the adaptive and innate immune cells, isolated from the graft, spleen, lymph nodes and blood was performed by flow cytometry at POD 3 and 7. Graft function was assessed by serum creatinine and urea levels. For in vitro analyses of intracellular signaling, oxidative stress and cell death murine primary PTEC were isolated and subjected to hypoxia (0.5% O2, w/o FCS, 24h) and reoxygenation (30min, 6h, 12h, 24h), ±rLcn2 (1µg/ml). Cell death and cytotoxoicty was determined by AnnV/PI staining and LDH release assay, respectively.
Results: rLcn2 significantly lowered CD8+ T cells in the allograft, LN and blood at POD 7, whereas their number remained unaffected in spleen. Nevertheless, the number of CD4+ T Lymphocytes was reduced only in lymph nodes. NKG2D+CD8+T cells and CD27+CD11b+NKp46+NK cells were the most prominent subpopulations of the cytotoxic lymphocytes whose frequencies were significantly reduced in graft, spleen and blood with the treatment of rLcn2. Besides, a significantly reduced infiltration of monocytes/macrophages was also observed at POD-7 with the said treatment. Importantly, degranulation capacity and IFNg production of intragraft and splenic CD4+ and CD8+ T cells were impaired in the treated animals. Besides, rLcn2 lowered hypoxia and reoxygenation induced cytotoxicity of the primary RTECs, associated with reduced caspase-3 cleavage and activation of Erk and AKt signaling.
Conclusion: rLcn2 treatments differentially affects the relative frequencies and activation of various immune cell. Besides, rLcn2 depicts cytoprotective effect on murine primary RTECs during H/R, possibly via activation of Erk and Akt signaling.

Molecular analysis of renal graft biopsies: comparing the Edmonton Molecular Microscope with the NanoString Human Organ Transplant Panel

J. Schmitz, H. Stark, S. Bartels, D. Jonigk, P. Halloran, G. Einecke, J.-H. Bräsen; Hannover, Edmonton/CDN

Objective: The renal transplant biopsy is the diagnostic gold standard and usually evaluated with the continuously expanded and updated Banff classification which is based on on descriptive, empirically-derived criteria and thus lacks precision. High-resolution determination of the graft inflammation by NanoString analysis, which was developed for formalin-fixed paraffin-embedded-derived (FFPE) RNA, should be a sufficient approach for objective molecular diagnosis of renal transplant biopsies and may improve our understanding of graft biology.
Method: We used well-annotated surveillance and indication biopsies from 63 patients whose time-matched second biopsy core had been frozen and analyzed by microarray in the INTERCOM/INTERCOMEX study. After reevaluation according to recent Banff consensus, RNA isolation of the FFPE biopsy was performed and led to sufficient RNA yields in 53 samples which were further processed for NanoString analysis using the nCounter Human Organ Transplant Panel.
Results: Morphologically, of the 53 samples analyzed (samples from 2011/12 and 2015), twenty-five patients showed no signs of rejection, twelve had borderline rejection, four showed cellular rejection, seven had humoral rejection, and five presented with combined rejection. Preliminary analysis of gene expression by T-distributed Stochastic Neighbor Embedding (t- SNE), Random Forest and Principal Component Analysis (PCA) showed clear differences between samples with rejection (humoral and cellular) and without rejection. Rejection samples revealed high expression of chemokine ligands compared to rejection-free tissues. A common pattern of samples without rejection and borderline rejection was observed. Our results displayed good correlation with the former molecular microarray-based diagnosis from the INTERCOM/INTERCOMEX study.
Conclusion: Molecular diagnostic approach using the NanoString platform may supplement morphological diagnosis of renal grafts especially in unclear cases and thus enhance precision diagnostics with small tissue requirement. Morphological and molecular evaluation in the same biopsy core from FFPE tissue enables direct histological-molecular correlation. Additionally, this technology also improves our understanding of pathophysiology in renal and other transplants.

EBV-associated Post-Transplant Lymphoproliferative Disorder: In Vitro Model for a Rational Modification of Immunosuppression

C. Thieme, M. Schulz, T. Roch, P. Wehler, L. Amini, R. Viebahn, M. Choi, M. Schmück-Heneresse, P. Reinke, T. H. Westhoff, N. Babel; Berlin, Herne, Bochum

Objective: Post-transplant lymphoproliferative Disorder (PTLD) is a life-threatening complication of long-lasting immunosuppression following transplantation. The most important reason is a failure of the immune system to control Epstein-Barr-Virus (EBV)-infected and transformed B-lymphocytes. This control is provided mainly by T cells and differently impaired by certain types of immunosuppressants. Therefore, a modification of immunosuppression is the first and most common treatment, but has to be balanced with respect to the risk of allograft rejection.
Method: We performed an in vitro study of EBV-antigen specific T cell cultures from healthy donors in the absence or presence of the immunosuppressants tacrolimus (TAC), cyclosporin A (CSA), prednisolone (PRED), rapamycin (RAPA) and mycophenolic acid (MPA) in clinically relevant concentrations. After a total of three weeks of culture we measured the proliferation, viability and phenotypes of the T cells and their activation marker profile, cytokine production as well as cytotoxicity upon restimulation with autologous lymphoblastoid cell lines (LCLs).


Results: We observed substantial differences in the monitored parameters between the immunosuppressants. T cells treated with RAPA showed the most favourable outcome in terms of proliferation, viability, functionality and cytolytic activity. Proliferation and viability of T cells was most prominently affected by MPA, while TAC and CSA were the strongest suppressors of cytokine production and cytolytic activity.

Conclusion: With our data, we provide a basis for the clinical decision for the reduction of immunosuppression in patients in risk of or affected by PTLD and add information to the complex puzzle of maintaining anti-viral immunity while preventing acute rejection. In line with the published clinical studies on this topic, a reduction of calcineurin inhibitors while keeping mTOR inhibitors seems to be a promising strategy for the modification of immunosuppression according to our in vitro model.

Calcineurin Inhibitor cyclosporine A but not tacrolimus stimulates proapoptotic unfolded protein response induced by endoplasmic reticulum stress

D. E. Yilmaz, K. Kirschner, H. Demirci, S. Bachmann, K. Mutig; Berlin

Objective: Calcineurin inhibitors such as cyclosporine A (CsA) or Tacrolimus (Tac) build the core of immunosuppressive regimen in patients undergoing organ transplantation. However, their nephrotoxic effect is a major limitation for long-term usage. We hypothesized that CsA compared to Tac exerts more pronounced toxic side effects at the cellular level, with endoplasmic reticulum (ER)-stress and maladaptive unfolded protein response (UPR) as the most prominent landmarks.
Method: To test this hypothesis we treated human embryonic kidney (HEK293) cells with CsA (10 µM) or Tac (10 µM) for 6h. The established ER-stress-inducer thapsigargin served as positive control. To study the molecular mechanisms of CNI-induced cell toxicity we generated HEK293 cells lacking the crucial UPR elements, PERK or ATF6 via CRISPR/Cas9-mediated gene editing technology. Abundances of the ER-stress sensor IRE1a, adaptive transcription factor XBP1, protein synthesis suppressor eIF2a and proapoptotic transcription factor CHOP were evaluated as endpoints.
Results: Treatment of native HEK293 cells with CsA or Tac equally increased phosphorylation of the known calcineurin substrate, NFAT, verifying the treatment protocols. CsA increased phosphorylation levels of IRE1a (p-IREa) and eIF2a (p-eIF2a) and protein abundance of CHOP and spliced XBP1 (sXBP1). In contrast, Tac enhanced only p-IRE1a and p-eIF2a abundance. CsA but not Tac significantly increased the number of cleaved caspase 3-expressing cells suggesting enhanced apoptosis rate. Treatment with the chemical chaperones, TUDCA and 4-PBA, partially abolished the CsA-induced increases of CHOP, suggesting alleviation of ER-stress. Knockdown of CsA binding partners, cyclophilin A and B, by siRNA reduced their expression approximately by half and increased CHOP expression suggesting that suppression of cyclophilins may contribute to CsA-induced cellular toxicity. PERK- or ATF6-deficiency blunted the increases of CHOP and sXBP1 in response to CsA, suggesting an implication of these pathways in CsA-induced ER-stress and UPR.
Conclusion: In summary, CsA but not Tac induces pronounced ER-stress and proapoptotic UPR. Pharmacological modulation of UPR bears the potential to alleviate CNI nephrotoxicity.

Akutes Transplantatversagen bei einer 79-jährigen Patientin

J. Gebhardt, J. Lang, N. Huber, E. Arli, I.A. Hauser, C. Betz, H. Geiger, W. Derwich, A. Thalhammer, N. Obermüller; Frankfurt a. M.

Hintergrund: Darstellung eines Leriche-Syndroms mit Beteiligung der Nierentransplantatarterie als seltene Ursache eines Transplantatversagens
Methode: Fallvorstellung (Case Report)
Ergebnisse: Eine 79-jährige Patientin mit rechtsseitiger Nierentransplantation im Jahr 1990 und guter Transplantatfunktion wird bei Harnwegsinfekt stationär aufgenommen. Eine generalisierte Atherosklerose ist bekannt. Aufgrund von Vorhofflimmern und einer stattgehabten tiefen Beinvenenthrombose (TBVT) besteht eine Antikoagulation mit Apixaban. Eine Osteoporose wird mit Östrogenen behandelt.
Unter der breit gewählten antiinfektiven Therapie sind die Infektionsparameter rasch rückläufig, jedoch entwickelt die Patientin am 10. Tag nach Aufnahme ein akutes Transplantatversagen. Sonographisch zeigt sich die Transplantatperfusion erst reduziert und ist später gar nicht mehr nachweisbar. Es kommt zur Anurie und die Hämodialyse muss eingeleitet werden.
In der CT-Angiographie zeigt sich letztlich ein Verschluss der Aorta descendens im Bereich der Iliacalbifurkation im Sinne eines Leriche-Syndroms mit Beteiligung der Transplantatarterie. Eine minimale Transplantatrestperfusion ist erhalten und erfolgt mutmaßlich über bereits etablierte Kollateralen. Klinisch ergibt sich kein Hinweis auf eine Ischämie der unteren Extremität. Mittels Implantation zweier gecoverter Stents in Kissing-Technik gelingt die Rekanalisation mit Wiederherstellung der Transplantatperfusion. Die Antikoagulation wird um ASS ergänzt und das Östrogenpräparat abgesetzt. Nach vier Dialysen kann die Nierenersatztherapie erfolgreich ausgelassen werden und die Transplantatfunktion erholt sich innerhalb weniger Wochen wieder nahezu auf das Ausgangsniveau.
Zusammenfassung: Beim Leriche-Syndrom handelt es sich um eine Sonderform der pAVK mit (Teil)Verschluss der distalen Aorta. Die Beteiligung eines Nierentransplantats stellt eine besondere Herausforderung dar. Differentialdiagnostisch sollte beim akuten Transplantatversagen immer eine Minderperfusion mit in Betracht gezogen werden. Diagnostisch wegweisend sind FKDS sowie die kontrastmittelgestütze Schnittbildgebung. Eine Östrogentherapie sollte bei multimorbiden, geriatrischen Patienten kritisch hinterfragt werden.


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