14:00 - 15:30
Poster DGfN 2020
Transplantation 2 (P111 - P118; LA26)
Hintergrund: Mittels eines Ansatzes des maschinellen Lernens wurde ein Modell zur Prädiktion des Langzeittransplantatüberleben (TxÜL) bis 15 Jahre nach NTx und zur Ermittlung der assoziierten Risikofaktoren erstellt.
Methode: Daten von 892 Patienten mit NTx zwischen 2000 und 2007 und Nachbeobachtung von bis zu 17 Jahren dienten zur Modelletablierung. Neben prä-NTx-Daten wurden Verlaufsdaten des 1. NTx-Jahres integriert, incl. der Befunde aus 2251 Protokoll- und 1214 Indikationsbiopsien. Das Modell wurde mit einer separaten Kohorte von 349 Patienten validiert. Rejektionen in Protokollbiopsien wurden mit Ausnahme von Borderline T-Zellabstoßungen behandelt.
Ergebnisse: Das für Tod zensierte TxÜL betrug 71% nach 15 Jahren. Hauptgründe für NTx-Verlust waren akute und chronische Rejektion (19%), andere spezifizierte histologische Läsionen (14%) und progressive chronische Dysfunktion ohne histologische Sicherung (34%). Das Prädiktionsmodell zeigte eine gute Performance zur Vorsage des Tx-ÜL mit einem Concordance Index von 0,79. Neben der GFR zu 12 Monaten nach NTx waren T-Zell- und Antikörpervermittelte Rejektionen -sowohl in Protokoll- als auch Indikationsbiopsien- von großer Bedeutung. Weitere wichtige Risikofaktoren waren rekurrierende und de novo Nierenerkrankungen, BK Virus Nephropathie, Übergewicht, Diabetes, koronare Herzkrankheit, monoklonale Gammopathie, verschiedene Infektionen, Spenderalter. In einer posthoc-Analyse hatten Patienten mit hohem prognostiziertem NTx-Verlustrisiko jenseits des 1. NTx-Jahres signifikant häufiger Rejektionen und donorspezifische Antikörper. Die Validierung des Modells an der unabhängigen Kohorte bestätigte die prädiktive Performance (Concordance Index 0,78) und gute Kalibrierung.
Zusammenfassung: Mit dem Modell ist eine frühzeitige Identifizierung von Patienten möglich, die einen stabilen Langzeitverlauf haben bzw. ihr Transplantat mit hoher Wahrscheinlichkeit vorzeitig verlieren. Dies erlaubt eine frühzeitige Stratifizierung und, über die identifizierten Risikofaktoren, individuell angepasste Monitoringstrategie und Therapieplanung.
Objective: Extracorporeal photopheresis (ECP) is a little-invasive therapeutic intervention, particularly used in T-cell mediated diseases. The mode of action primarily encompasses modulation of immunoregulatory processes. In solid organ transplantation, treatment of refractory rejection by ECP has been reported; still the optimal indications for this treatment have yet to be determined. We report our first experience with ECP in a case series of patients with high immunologic risk and refractory polyoma virus-associated nephropathy (PVAN).
Method: Three patients with refractory PVAN to center standard therapy with high immunological risk, where reduction in immunosuppression implied the risk of rejection, were planned to receive 8-10 sessions of ECP.
Results: One patient suffered acute rejection early after AB0-incompatible living donor kidney transplantation, and developed PVAN three months later. Two patients displayed kidney allograft dysfunction due to PVAN after simultaneous pancreas and kidney transplantation (SPK). All patients were refractory to the PVAN standard center protocol (conversion to mTOR-based immunosuppression, cidofovir). Reduction in overall immunosuppression resulted in rising HbA1c in SPK patients. After initiation of ECP, the first patient showed remission of PVAN with stabilization of allograft function. One patient after SPK stabilized pancreas function but displayed progressive kidney allograft dysfunction after 8 sessions of ECP. Yet the patient is still off dialysis 11 months after diagnosis of PVAN. The other patient died in the early course due to severe COVID-19 infection, unrelated to ECP.
Conclusion: In conclusion, ECP, due to its immunomodulatory effects, might represent a novel therapeutic approach for selected patients with high immunologic risk allowing for reduction of maintenance immunosuppression. Early intervention might be necessary and further data are highly warranted to identify the correct patient selection, treatment cycles and timing.
Hintergrund: Gegenstand unserer klinischen Studie ist die Untersuchung der Immunantwort von nierentransplantierten Patienten auf eine sequentielle Impfung mit dem Pneumokokken-Konjugat-Impfstoff PCV13 (Prevenar®), gefolgt von dem Pneumokokken-Polysaccharid-Impfstoff PPSV23 (Pneumoax®) nach sechs Monaten.
Methode: Nach schriftlicher Einwilligung der Patienten erfolgt die erste Impfung mit Prevenar® und eine Blutentnahme zur Titerbestimmung. Sechs Monate nach der ersten Impfung folgt die zweite Impfung mit Pneumovax® sowie eine weitere Titerkontrolle. Darüber hinaus erfolgen weitere Titerbestimmungen 1, 7 und 12 Monate nach der ersten Impfung.
Immunantworten nach Pneumokokken-Impfung sollen über Serotyp-spezifische IgG-Konzentrationen oder funktionelle Antikörperkonzentrationen (IgG) quantifiziert werden, die mit dem Opsonophagocytic Assay (OPA) und ELISA gemessen werden.
Ergebnisse: Vorläufig lässt sich aufgrund der erhobenen Daten erkennen, dass bei 29 Patienten mit vollständigen Daten ein Anstieg des Anti-Pneumokokken-IgG-Titers von 72,18 mg/l auf 147,00 mg/l nach 12 Monaten beobachtet wurde. Dabei lagen die Konzentrationsmaxima mit 131,37 mg/l und 172,13 mg/l im Monat 1 und 7, also jeweils einen Monat nach der Impfung. Zusätzlich zeigt sich ein statistisch signifikanter Einfluss der Therapie mit Mycophenolat-Mofetil (MMF) auf die Antikörperkonzentration nach 7 und 12 Monaten. Patienten unter MMF Therapie weisen niedrigere Titer im Vergleich zu Patienten ohne MMF Therapie auf.
Zusammenfassung: Die Ableitung einer geeigneten Impfempfehlung gegen Pneumokokken für nierentransplantierte Patienten ist nach Komplettierung der Studie wünschenswert.
Objective: The expression of nuclear factor of activated T-cells (NFAT)-regulated genes in the peripheral blood has been suggested as a potentially useful immune monitoring tool to individualize tacrolimus (Tac) therapy. The aim of the IMAGEN study was to characterize the possibility of monitoring of residual NFAT-regulated gene expression in renal allograft recipients in a multicenter approach.
Method: 64 de novo renal transplant recipients from three European centers were enrolled. All patients were treated with Tac, mycophenolic acid, and corticosteroids. NFAT-regulated gene expression (NFAT-RGE; IL-2, IFNy, GM-CSF) was evaluated by quantitative real-time PCR in whole blood samples at day 7, month 1, 2, 3, and 6 after transplantation.
Results: NFAT-RGE and all three gene expression, IL-2, IFNy, and GM-CSF, correlated inversely to the Tac levels with the highest inhibition of gene expression at the time of the peak Tac level at 1.5 hours after drug intake (day 7; NFAT-RGE 16±9%, IL-2 RGE 14±17%, IFNy RGE 20±18%, GM-CSF RGE 13±15%). NFAT-RGE showed a high interindividual variability (1 to 61%). RGE increased in the first two months from 16±9% to 34±21%, and was stable thereafter. ROC analyses for the ability of NFAT-RGE to discriminate patients at risk for the combined endpoint (death, transplant failure, and acute rejection) from stable patients showed a good diagnostic accuracy (p=0.005; AUC = 0.797; 95% CI 0.607-0.988). Simultaneous maximization of sensitivity and specificity obtained from ROC curves was shown at NFAT-RGE of 30%.
Conclusion: Monitoring of NFAT-RGE may provide additional useful information for physicians to achieve individualized treatment adjustments based on the immunomodulatory effect of Tac, thus preventing serious clinical events. The IMAGEN study demonstrated that NFAT-RGE measurements can be applied in trials with multicenter approach.
Objective: Immunosuppressive strategies in longterm renal allograft recipients with progressive graft dysfunction are controversial. Although belatacept (Bela) has been associated with increased acute rejection rates early post-transplant, it may avoid CNI toxicity, non-adherence and risk of donor-specific antibody formation. Only few data are available on switching immunosuppression in patients at increased immunological risk and at later stages after transplantation.
Method: 30 long-term kidney transplant recipients (KTR), including 2 combined pancreas-kidney transplant patients converted from CNI to belatacept >60 months after transplantation with moderate to severe graft dysfunction (GFR≤45 mL/min) were analyzed, retrospectively. Main reasons to switch were CNI-toxicity and non-adherence. Positivity for donor-specific antibodies (DSA) at conversion was 46.7%. Biopsies were classified according to the Banff 2015 criteria. Group differences were assessed in a univariate analysis using Mann Whitney U or Chi square test, respectively. Multivariate analysis of risk factors for treatment failure was performed using a binary logistic regression model including significant predictors from the univariate analysis. 56 control KTR matched for donor and recipient characteristics were used as a control cohort. During the same observation period the control cohort remained on a calcineurin inhibitor-based treatment regimen.
Results: In the Bela cohort patient survival at 12/24 months was 96.7%/90%, while graft survival censored for death was 79.3%/66.7%. In patients with functioning grafts, median GFR improved from 22.5 mL/min to 24.5 mL/min at 24 months (mean ΔGFR from GFR at switch 1.8 ± 7.9 mL/min). From univariate analysis of multiple risk factors for graft loss, GFR<25 mL/min (p=0.042) and Banff microvascular inflammation (MVI) sum score ≥2 (p=0.023) at conversion were significant at 24 months. DSA positivity was lower in the control cohort (percentage of 33.9%). Graft survival at 24 months was comparable, albeit without increase of mean GFR in patients with functioning grafts (ΔGFR of -3.6 ± 8.5 mL).
Conclusion: Rescue therapy with conversion to belatacept is feasible in patients with worsening renal function, even many years after transplantation. The benefit in patients with MVI and severe GFR impairment remains to be investigated.
Objective: The histological assessment of kidney graft biopsies is the gold standard in transplantation medicine. However, histology has major drawbacks including low reproducibility, low sensitivity and low specificity. A high data resolution is achieved by biopsy transcriptomics. However, fully unsupervised analyses without any a priori hypotheses are missing. We hypothesized that a data-driven transcriptome analysis unravels new disease phenotypes that are undetectable in histology.
Method: We used several published kidney transplant transcriptomic data as test and validation data sets. Leukocyte estimations were calculated by RNA deconvolution, gene networks were determined by co-regulation analysis, and immune phenotypes were defined by high dimensional nearest neighbor clustering.
Results: In 4 independent data sets at least 5 common immune phenotypes could be detected with differentially expressed signatures of homeostasis, inflammation, fibrosis, cellular and humoral rejection. Specific Banff diagnoses show a high degree of immune variability. While some phenotypes resemble the Banff classification, at least two immune phenotypes seem new. They show a significant correlation with graft survival, tissue remodeling pathways and fibroblast infiltration, suggesting a clinically relevant allograft disease that is not reliably detected in histology.
Conclusion: Our data provide a first comprehensive large-scale analysis of graft immune phenotypes independent of histological classification. These types of data-driven analyses will be crucial to overcome the issues of histology, and expand our understanding of immune responses in the allograft.
Objective: We have recently shown that donor blood cells, modified in vitro by an alkylating agent (MIC, modified immune cells), induced specific immunosuppression against the allogeneic donor when administered prior to transplantation (Morath, JCI 2020). An additional important finding was an up to 68-fold increase in the frequency of immunosuppressive CD19+CD24hiCD38hi transitional B lymphocytes compared to the frequency in transplanted controls without MIC infusions. The question arises whether donor-specific immunosuppression and increased regulatory B lymphocytes (Breg) are permanently detectable in MIC-treated patients.
Method: Four patients from a phase-I clinical trial who had received 1.5x108 MIC per kg b.w. on day -7 before living donor kidney transplantation and who were on low immunosuppression during follow-up were compared to 12 transplanted control patients without MIC infusions.
Results: MIC-treated patients showed an excellent clinical course with no donor-specific human leukocyte antigen antibodies or rejection episodes. On day 1080 after transplantation, graft function was stable with a median serum creatinine of 1.59 mg/dL. Patients had absent in vitro lymphocyte reactivity against stimulatory donor blood cells while reactivity against third party cells was preserved as an indication of continued donor-specific unresponsiveness. CD19+CD24hiCD38hi and IL10+CD19+CD24hiCD38hi Breg were with 2.2/µL and 1.0/µL, respectively, strikingly higher than the 0.0/µL (P<0.001) and 0.0/µL (P<0.001) in transplanted controls and in the range of the numbers of healthy individuals (N=34: 2.4/µL, P=0.73, and 0.8/µL, P=0.60). In addition, significantly higher Breg numbers were found for CD1d+ (2.2/µL vs. 0.3/µL, P=0.0071), CD19+CD38+CD147+CD1d+ (2.2/µL vs. 0.1/µL, P=0.0071), CD19+CD25+ (4.0/µL vs. 0.2/µL, P=0.0077), CD19+CD25+CD73+CD71+ (2.5/µL vs. 0.2/µL, P=0.013), CD19+CD25+CD73-CD71+ (0.7/µL vs. 0.0/µL, P=0.0011), CD19+CD24hiCD27+ memory (3.5/µL vs. 0.3/µL, P=0.029), and IL10+CD19+CD24hiCD27+ memory Breg (1.6/µL vs. 0.3/µL, P=0.042). No such differences were observed for CD4+CD25+CD127-FoxP3+ Treg (5.6/µL vs. 5.3/µL, P=0.68) or different Treg subsets when comparing the four MIC-treated patients to transplanted controls without MIC infusions.
Conclusion: Donor-specific immunosuppression after MIC infusion is long-lasting and is associated with a striking increase in Breg at various stages of B cell development, including memory Breg.
Objective: After renal transplantation, complement is involved in the pathogenesis of renal transplant complications like ischemia reperfusion injury (I/R), rejection and dysfunction. However, it is still unclear which transplant conditions are responsible for the activation of complement pathways and induction of endogenous regulators and inhibitors of the complement system.
Method: Using a well-characterized cohort of 28 patients with no rejection (n=7), delayed graft function (DGF, n=7), cellular (TCMR, n=7) or humoral rejection (ABMR, n=7) and corresponding 0-biopsies, we analyzed differences in complement reaction depending on the type of renal transplant complication. For this purpose, RNA was isolated from FFPE sections and quantified with the nCounter® Human Organ Transplant Panel of NanoString and correlated with transplant conditions. In addition, C1q and C3c complement deposition was analyzed by immunohistochemistry.
Results: In zero-biopsies of transplants that developed ABMR or TCMR later on the expression of several complement-related genes tended to be higher , but the differences did not reach the level of significance except for the complement receptor 3 subunit CD18, which was sig. increased in ABMR (1.85±0.7 fold; p=0.02) compared to controls. Similarly, staining for C1q and C3c was comparable in all zero-biopsies. In contrast, in follow-up biopsies from allografts with TCMR and ABMR mRNA expression of C1qA, C1qB was significantly elevated compared to controls. In TCMR biopsies, mRNA expression of several complement-related genes including C1s, C3, complement factor B (CFB) and complement regulators like CFH, CR1 and SERPING1 was significantly increased. Interstitial C1q and C3c deposition was also significantly higher in TCMR and ABMR. Interestingly, the expression levels of at least 17 of 35 complement related genes in both zero- and follow-up biopsies correlated with the cold ischemia time. A particular strong positive correlation with cold ischemia time was detected for C1q (r=0.709, p=0.001 in zero-biopsies and r=0.520, p=0.005 in follow-up biopsies) and CD11b (r=0.622, p=0.001 in zero-biopsies and r=0.627, p=0.001 in follow-up biopsies).
Conclusion: Many complement-related genes were up-regulated in biopsies with ABMR and TCMR and correlated with the cold ischemia time, indicating that complement activation is primarily dependent on transplant conditions and thus an important factor in the pathogenesis of transplant rejection.
Objective: Covid-19 presents a new challenge to transplantation medicine. Patients with kidney transplants and those requiring dialysis do not seem to be more prone to infection with SARS-CoV-2, but case mortality rate is significantly higher. Since the beginning of the global pandemic, dialysis patients have to face the additional problem of a reduced chance of receiving a transplant because organ offers have plummeted even if Germany is not so affected like other countries. In future times we have to deal with different problems in transplantation medicine like the risk of infection under immunosuppression, the unknown risk of reinfection and unknown effect of vaccinations as well as outcome of solid organ transplantation after recently survived covid-infection.
Results: Case report: In May 2020, a 65-year-old dialysis patient received a kidney from a 70-year-old deceased donor with an eGFR of 94ml/min. The recipient herself was hospitalised for 14 days due to Covid-19 pneumonia and discharged only 6 weeks before the organ offer. Her course had been mild with nasal oxygen supply and without need high-flow therapy or NIV. At the time of the transplantation, the patient was completely symptom-free with no evidence of residual signs of infection. Chest X-ray did not show infiltrates. The transplantation was without complications with an immuno-suppressive regimen consisting of Tacrolimus, mycophenolate and steroids after induction with Basiliximab. The graft achieved primary function with a serum creatinine of 1.5mg/dl at discharge. While SARS-CoV2 PCR in the throat gargle sample remained negative, antibody testing for SARS-CoV2 IgG was positive. In the short-term course, the patient developed no evidence of recurrent symptoms of COVID-19 with a stable kidney function two month after transplantion. IgG detection is still possible without any knowing about neutralizing qualities.
Conclusion: After full recovery of COVID-19 pneumonia, it is still unclear whether and for long immunity occurs. Moreover, it is unknown whether recovered patients are at risk for reinfection and how long transplantation should be delayed. Since there is no evidence of virus persistence in the literature, we decided to proceed with transplantation at this very early time. Although our follow up period is very short, we feel that the benefits of a successful transplant outweighed the existing risks. Long-term follow up willprovide important insights into the course of immune responses to SARS-CoV-2 after renal transplantation.
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