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Background: The response to severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) vaccination is severely impaired in patients on maintenance immunosuppression after kidney transplantation., Methods: We conducted a prospective cohort study of 194 kidney transplant recipients (KTR) who exhibited no response to SARS-CoV-2 vaccinations (i.e., SARS-CoV-2 spike protein antibodies ≤264 U/mL) and had no prior documented infection. Patients received 300 mg of cilgavimab/tixagevimab as SARS-CoV-2 pre-exposure prophylaxis (PrEP) between March 4, 2022, and May 3, 2022 and were contrasted to a matched cohort of 186 KTRs also without immunization again defined as SARS-CoV-2 spike protein antibodies ≤264 U/mL and no documented prior infection. The primary outcome was the serum kinetics of cilgavimab/tixagevimab, the secondary endpoints were time to SARS-CoV-2 breakthrough infection, severity of disease and variant specific live viral in vitro neutralization tests of patient sera., Findings: Longitudinal serum level monitoring showed a half-life of 91 days for both antibodies (95% CI 86-95 days for cilgavimab and 85-96 days for tixagevimab) in KTRs. In vitro neutralization tests showed effectiveness against the BA.2 omicron subvariant but not BA.5. The cumulative incidence of SARS-CoV-2 infections until May 15, 2022, (BA.2 dominance) was 15/194 vs 36/186 in the PrEP and control group respectively (OR = 0.35, 95% CI 0.18-0.66) but was not different thereafter (BA.4/5 dominance). The number of severe infections during the BA.2 period was lower in the prophylaxis than in the control group (OR = 0.37, 95% CI 0.17-0.79)., Interpretation: This study showed that SARS-CoV-2 PrEP with cilgavimab/tixagevimab demonstrated clinical effectiveness against variants that are neutralised (BA.2) but not against BA.4/5., Funding: This study was funded by the Medical University of Vienna and an unrestricted grant from AstraZeneca (ESR-21-21585)., Competing Interests: Declaration of interests “The authors declare no competing interests for this manuscript”, (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Background: Induction of donor-specific tolerance is a promising approach to achieve long-term graft patency in transplantation with little to no maintenance immunosuppression. Changes to the recipient's T cell receptor (TCR) repertoire are understood to play a pivotal role in the establishment of a robust state of tolerance in chimerism-based transplantation protocols., Methods: We investigated changes to the TCR repertoires of patients participating in an ongoing prospective, controlled, phase I/IIa trial designed to evaluate the safety and efficacy of combination cell therapy in living donor kidney transplantation. Using high-throughput sequencing, we characterized the repertoires of six kidney recipients who also received bone marrow from the same donor (CKBMT), together with an infusion of polyclonal autologous Treg cells instead of myelosuppression., Findings: Patients undergoing combination cell therapy exhibited partial clonal deletion of donor-reactive CD4 + T cells at one, three, and six months post-transplant, compared to control patients receiving the same immunosuppression regimen but no cell therapy (p = 0.024). The clonality, R20 and turnover rates of the CD4 + and CD8 + TCR repertoires were comparable in both groups, showing our protocol caused no excessive repertoire shift or loss of diversity. Treg clonality was lower in the case group than in control (p = 0.033), suggesting combination cell therapy helps to preserve Treg diversity., Interpretation: Overall, our data indicate that combining Treg cell therapy with CKBMT dampens the alloimmune response to transplanted kidneys in humans in the absence of myelosuppression., Funding: This study was funded by the Vienna Science and Technology Fund (WWTF)., Competing Interests: Declaration of interests The authors have declared that no conflict of interest exists., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Membranous nephropathy (MN) is a leading cause of kidney failure worldwide and frequently recurs after transplant. Available data originated from small retrospective cohort studies or registry analyses; therefore, uncertainties remain on risk factors for MN recurrence and response to therapy. Within the Post-Transplant Glomerular Disease Consortium, we conducted a retrospective multicenter cohort study examining the MN recurrence rate, risk factors, and response to treatment. This study screened 22,921 patients across 3 continents and included 194 patients who underwent a kidney transplant due to biopsy-proven MN. The cumulative incidence of MN recurrence was 31% at 10 years posttransplant. Patients with a faster progression toward end-stage kidney disease were at higher risk of developing recurrent MN (hazard ratio [HR], 0.55 per decade; 95% confidence interval [CI], 0.35-0.88). Moreover, elevated pretransplant levels of anti-phospholipase A2 receptor (PLA2R) antibodies were strongly associated with recurrence (HR, 18.58; 95% CI, 5.37-64.27). Patients receiving rituximab for MN recurrence had a higher likelihood of achieving remission than patients receiving renin-angiotensin-aldosterone system inhibition alone. In sum, MN recurs in one-third of patients posttransplant, and measurement of serum anti-PLA2R antibody levels shortly before transplant could aid in risk-stratifying patients for MN recurrence. Moreover, patients receiving rituximab had a higher rate of treatment response., Competing Interests: Declaration of competing interest The authors of this manuscript have conflicts of interest to disclose as described by the American Journal of Transplantation. Helio Tedesco Silva is supported by research grants from Novartis, Natera, and Merck & Co. through his institution. He received honoraria for lectures from Takeda, EMS, CardeDx and Natera. Additionally, he received monetary support from Takeda to attend meetings. A. Bernard Collins receives royalties from Elsevier. He also reports receiving honoraria from Euroimmun. Nikhil Agrawal has employment stocks and options from CareDx Inc. He is also currently employed by CareDx Inc. Ayman Al Jurdi is supported by AstraZeneca through grant funding for an investigator-initiated study related to another project. Roberto C. Manfro served on the data safety monitoring board of Instituto Butanatan in São Paulo, Brazil, for which he did not receive any payments. Giorgia Comai received honoraria from Novartis, Hansa Biopharma, and Alexion. Additionally, she is a part of the Biotest Advisory Board, for which she receives payments. Paolo Cravedi is supported by the NIH award R01 DK123234 and has received research funding from Chinook Therapeutics. Leonardo V. Riella is supported by the NIH award R01 AI143887 and has received research funding for unrelated projects from Visterra, Caredx, AstraZeneca, Natera, and Bristol-Meyers-Squibb. All remaining authors have nothing to disclose., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The dysregulated immune response and inflammation resulting in severe COVID-19 are still incompletely understood. Having recently determined that aberrant death-ligand-induced cell death can cause lethal inflammation, we hypothesized that this process might also cause or contribute to inflammatory disease and lung failure following SARS-CoV-2 infection. To test this hypothesis, we developed a novel mouse-adapted SARS-CoV-2 model (MA20) that recapitulates key pathological features of COVID-19. Concomitantly with occurrence of cell death and inflammation, FasL expression was significantly increased on inflammatory monocytic macrophages and NK cells in the lungs of MA20-infected mice. Importantly, therapeutic FasL inhibition markedly increased survival of both, young and old MA20-infected mice coincident with substantially reduced cell death and inflammation in their lungs. Intriguingly, FasL was also increased in the bronchoalveolar lavage fluid of critically-ill COVID-19 patients. Together, these results identify FasL as a crucial host factor driving the immuno-pathology that underlies COVID-19 severity and lethality, and imply that patients with severe COVID-19 may significantly benefit from therapeutic inhibition of FasL., (© 2024. The Author(s).)

Background: Early progression of chronic histologic lesions in kidney allografts represents the main finding in graft attrition. The objective of this retrospective cohort study was to elucidate whether HLA histocompatibility is associated with progression of chronic histologic lesions in the first year post-transplant. Established associations of de novo donor-specific antibody (dnDSA) formation with HLA mismatch and microvascular inflammation (MVI) were calculated to allow for comparability with other study cohorts., Methods: We included 117 adult kidney transplant recipients, transplanted between 2016 and 2020 from predominantly deceased donors, who had surveillance biopsies at 3 and 12 months. Histologic lesion scores were assessed according to the Banff classification. HLA mismatch scores [i.e. eplet, predicted indirectly recognizable HLA-epitopes algorithm (PIRCHE-II), HLA epitope mismatch algorithm (HLA-EMMA), HLA whole antigen A/B/DR] were calculated for all transplant pairs. Formation of dnDSAs was quantified by single antigen beads., Results: More than one-third of patients exhibited a progression of chronic lesion scores by at least one Banff grade in tubular atrophy (ct), interstitial fibrosis (ci), arteriolar hyalinosis (ah) and inflammation in the area of interstitial fibrosis and tubular atrophy (i-IFTA) from the 3- to the 12-month biopsy. Multivariable proportional odds logistic regression models revealed no association of HLA mismatch scores with progression of histologic lesions, except for ah and especially HLA-EMMA DRB1 [odds ratio (OR) = 1.10, 95% confidence interval (CI) 1.03-1.18]. Furthermore, the established associations of dnDSA formation with HLA mismatch and MVI (OR = 5.31, 95% CI 1.19-22.57) could be confirmed in our cohort., Conclusions: These data support the association of HLA mismatch and alloimmune response, while suggesting that other factors contribute to early progression of chronic histologic lesions., (© The Author(s) 2023. Published by Oxford University Press on behalf of the ERA.)

Background and Hypothesis: The decision for acceptance or discard of the increasingly rare and marginal brain-dead donor kidneys in Eurotransplant (ET) countries has to be made without solid evidence. Thus, we developed and validated flexible clinicopathological scores called 2-Step Scores for the prognosis of delayed graft function (DGF) and one-year death-censored transplant loss (1y-tl) reflecting the current practice of six ET countries including Croatia and Belgium., Methods: The training set was n=620 for DGF and n=711 for 1y-tl, with validation sets n=158 and n=162. In step 1, stepwise logistic regression models including only clinical predictors were used to estimate the risks. In step 2, risk estimates were updated for statistically relevant intermediate risk percentiles with nephropathology., Results: Step 1 revealed an increased risk of DGF with increased cold ischaemia time, donor and recipient BMI, dialysis vintage, number of HLA-DR mismatches or recipient CMV IgG positivity. On the training and validation set, c-statistics were 0.672 and 0.704, respectively. At a range between 18% and 36%, accuracy of DGF-prognostication improved with nephropathology including number of glomeruli and Banff cv (updated overall c statistics of 0.696 and 0.701, respectively).Risk of 1y-tl increased in recipients with cold ischaemia time, sum of HLA-A. -B, -DR mismatches and donor age. On training and validation sets, c-statistics were 0.700 and 0.769, respectively. Accuracy of 1y-tl prediction improved (c-statistics = 0.706 and 0.765) with Banff ct. Overall, calibration was good on the training, but moderate on the validation set; discrimination was at least as good as established scores when applied to the validation set., Conclusion: Our flexible 2-Step Scores with optional inclusion of time-consuming and often unavailable nephropathology should yield good results for clinical practice in ET, and may be superior to established scores. Our scores are adaptable to donation after cardiac death and perfusion pump use., (© The Author(s) 2024. Published by Oxford University Press on behalf of the ERA.)

Despite the similar clinical outcomes after renin-angiotensin system (RAS) inhibitor (RASi) continuation or withdrawal in COVID-19, the effects on angiotensin-converting enzyme 2 (ACE2) and RAS metabolites remain unclear. In a substudy of the randomized controlled Austrian Corona Virus Adaptive Clinical Trial (ACOVACT), patients with hypertension and COVID-19 were randomized 1:1 to either RASi continuation (n = 30) or switch to a non-RASi medication (n = 29). RAS metabolites were analyzed using a mixed linear regression model (n = 30). Time to a sustained clinical improvement was equal and ACE2 did not differ between the groups but increased over time in both. Overall ACE2 was higher with severe COVID-19. ACE-S and Ang II levels increased as expected with ACE inhibitor discontinuation. These data support the safety of RASi continuation in COVID-19, although RASi were frequently discontinued in our post hoc analysis. The study was not powered to draw definite conclusions on clinical outcomes using small sample sizes., Competing Interests: M.P. is employed by Attoquant Diagnostics, Vienna/Austria, a company that received payments for RAS-Fingerprint and ACE2 quantification., (© 2023 The Author(s).)

Background Sotrovimab, a monoclonal antibody against SARS-CoV-2, is used as a pre-exposition prophylaxis (PrEP) against COVID-19, but monitoring strategies using routine test systems have not been defined. Methods Twenty kidney transplant recipients without antibodies after vaccination received 500 mg Sotrovimab. Antibody levels were quantified over eight weeks using live-virus neutralization (BA1 and BA2), antibody binding assays (TrimericS, Elecsys, QuantiVAC) and surrogate virus neutralization tests (sVNTs; TECOmedical, cPass and NeutraLISA). Results Sotrovimab neutralized both Omicron subvariants (BA1 NT titer 90 (+-50) > BA2 NT titer 33 (+-15) one hour post infusion). Sotrovimab was measurable on all used immunoassays, although a prior 1:100 dilution was necessary for Elecsys due to a presumed prozone effect. The best correlation with live-virus neutralization titers was found for QuantiVAC and TrimericS, with a respective R 2 of 0.65/0.59 and 0.76/0.57 against BA1/BA2. Elecsys showed an R 2 of 0.56/0.54 for BA1/BA2, respectively. sVNT values increased after infusion but had only a poor correlation with live-virus neutralization titers (TECOmedical and cPass) or did not reach positivity thresholds (NeutraLISA). Conclusion Antibody measurements by the used immunoassays showed differences in antibody levels and only a limited correlation with neutralization capacity. We do not recommend sVNTs for monitoring SARS-CoV-2 neutralization by Sotrovimab.

Anti-SARS-CoV-2 vaccination of dialysis patients has been proven to be safe and effective to reduce COVID-19-related morbidity and mortality. However, data on the durability of anti-SARS-CoV-2 antibodies post-vaccination in peritoneal dialysis (PD) patients are scarce. In this prospective single-center cohort study we measured anti-SARS-CoV-2 RBD antibodies 3 and 6 months after the 3rd dose of the mRNA-1273 vaccine in 27 adult PD patients and recorded breakthrough infections. Furthermore, in a mixed model analysis, we analyzed potential factors influencing the humoral response following vaccination. Anti-SARS-CoV-2 RBD antibody levels declined from 21,424 BAU/mL at 1 month to 8397 BAU/mL at 3 months and to 5120 BAU/mL at 6 months after the 3rd dose, but remained higher than pre-3rd dose levels (212 BAU/mL). Eight patients (29.6%) were infected with SARS-CoV-2 within six months from the 3rd dose during the Omicron wave. Previous high antibody levels, high glomerular filtration rate (GFR) and low Davies Comorbidity Score were associated with higher anti-SARS-CoV-2 antibody levels after the booster. In conclusion, PD patients exhibited a robust and durable humoral response after a third dose of the mRNA-1273 vaccine. A high GFR and low comorbidity as well as previous high antibody levels predicted a better humoral response to vaccination.

We aimed to assess the systemic and hepatic renin-angiotensin-system (RAS) fingerprint in advanced chronic liver disease (ACLD). This prospective study included 13 compensated (cACLD) and 12 decompensated ACLD (dACLD) patients undergoing hepatic venous pressure gradient (HVPG) measurement. Plasma components (all patients) and liver-local enzymes (n = 5) of the RAS were analyzed using liquid chromatography-tandem mass spectrometry. Patients with dACLD had significantly higher angiotensin (Ang) I, Ang II and aldosterone plasma levels. Ang 1-7, a major mediator of the alternative RAS, was almost exclusively detectable in dACLD (n = 12/13; vs. n = 1/13 in cACLD). Also, dACLD patients had higher Ang 1-5 (33.5 pmol/L versus cACLD: 6.6 pmol/L, p < 0.001) and numerically higher Ang III and Ang IV levels. Ang 1-7 correlated with HVPG (ρ = 0.655; p < 0.001), von Willebrand Factor (ρ = 0.681; p < 0.001), MELD (ρ = 0.593; p = 0.002) and interleukin-6 (ρ = 0.418; p = 0.047). Considerable activity of ACE, chymase, ACE2, and neprilysin was detectable in all liver biopsies, with highest chymase and ACE2 activity in cACLD patients. While liver-local classical and alternative RAS activity was already observed in cACLD, systemic activation of alternative RAS components occurred only in dACLD. Increased Ang 1-7 was linked to severe liver disease, portal hypertension, endothelial dysfunction and inflammation., (© 2023. The Author(s).)

Reducing the recipient's T cell repertoire is considered to increase the efficacy of regulatory T cell (Treg) therapy. This necessitates timing the administration of antithymocyte globulin (ATG) early enough before adoptive cell therapy (ACT) so that residual serum ATG does not deplete the transferred Tregs. The optimum time point in this regard has not been defined. Herein, we report the effects of residual serum ATG on the viability of an in vitro expanded Treg cell product used in a clinical trial of ACT in kidney transplant recipients (NCT03867617). Patients received ATG monotherapy (either 6 or 3 mg/kg body weight) without concomitant immunosuppression 2 to 3 weeks before transplantation and Treg transfer. An anti-ATG immunoglobulin G (IgG) immune response was elicited in all patients within 14 days. In turn, the elimination of total and Treg-specific ATG was accelerated substantially over control patients receiving the same dose of ATG with concomitant immunosuppression. However, ATG serum concentrations of <1 μg/mL, which had previously been reported as subtherapeutic threshold, triggered apoptosis of Tregs in vitro. Therefore, ATG levels need to decline to lower levels than those previously thought for efficacious Treg transfer. In 5 of 6 patients, such low levels of serum ATG considered safe for Treg transfer were reached within 2 weeks after ATG administration., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: Increased left atrial (LA) size is a risk factor for cardiovascular events and all-cause mortality. It is closely related to left ventricular hypertrophy and chronic volume overload, both of which are common in hemodialysis. Calcimimetic treatment with etelcalcetide (ETL) previously showed an inhibitory effect on left ventricular mass index (LVMI) progression in this population., Methods: This is a post hoc analysis of the EtECAR-HD trial, where 62 patients were randomized to ETL or alfacalcidol (ALFA) for 1 year. LA volume index (LAVI) was measured using cardiac magnetic resonance imaging. The aim of the study was to investigate whether ETL was associated with a change of LAVI., Results: Median baseline levels of LAVI were 40 mL/m2 (31, 54 IQR) in the ETL group and 36 mL/m2 (26, 46 IQR) in the ALFA group. In the ITT population, the change of LAVI was 5.0 mL/m2 [95% CI: -0.04, 10] lower under ETL, compared to ALFA (p = 0.052, R2adj = 0.259). In the PP population, the difference in LAVI changes widened to 5.8 [95% CI: 0.36, 11], p = 0.037, R2adj = 0.302). Secondary analysis showed that the study delta of LVMI was correlated with the LAVI delta (r = 0.387) and that an inclusion of LVMI delta in the ANCOVA model mediated the effect on LAVI delta to β = 3.3 [95% CI: -0.04, 10] (p = 0.2, R2adj = 0.323). The same could not be observed for parameters assessing the volume status., Conclusions: The analysis indicates that ETL could inhibit LAVI progression compared with ALFA. This effect was mediated by the change of LVMI., (© 2023 The Author(s). Published by S. Karger AG, Basel.)

Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

SARS-CoV-2 gains cell entry via angiotensin-converting enzyme (ACE) 2, a membrane-bound enzyme of the "alternative" (alt) renin-angiotensin system (RAS). ACE2 counteracts angiotensin II by converting it to potentially protective angiotensin 1-7. Using mass spectrometry, we assessed key metabolites of the classical RAS (angiotensins I-II) and alt-RAS (angiotensins 1-7 and 1-5) pathways as well as ACE and ACE2 concentrations in 159 patients hospitalized with COVID-19, stratified by disease severity (severe, n = 76; non-severe: n = 83). Plasma renin activity (PRA-S) was calculated as the sum of RAS metabolites. We estimated ACE activity using the angiotensin II:I ratio (ACE-S) and estimated systemic alt-RAS activation using the ratio of alt-RAS axis metabolites to PRA-S (ALT-S). We applied mixed linear models to assess how PRA-S and ACE/ACE2 concentrations affected ALT-S, ACE-S, and angiotensins II and 1-7. Median angiotensin I and II levels were higher with severe versus non-severe COVID-19 (angiotensin I: 86 versus 30 pmol/L, p < 0.01; angiotensin II: 114 versus 58 pmol/L, p < 0.05), demonstrating activation of classical RAS. The difference disappeared with analysis limited to patients not taking a RAS inhibitor (angiotensin I: 40 versus 31 pmol/L, p = 0.251; angiotensin II: 76 versus 99 pmol/L, p = 0.833). ALT-S in severe COVID-19 increased with time (days 1-6: 0.12; days 11-16: 0.22) and correlated with ACE2 concentration (r = 0.831). ACE-S was lower in severe versus non-severe COVID-19 (1.6 versus 2.6; p < 0.001), but ACE concentrations were similar between groups and correlated weakly with ACE-S (r = 0.232). ACE2 and ACE-S trajectories in severe COVID-19, however, did not differ between survivors and non-survivors. Overall RAS alteration in severe COVID-19 resembled severity of disease-matched patients with influenza. In mixed linear models, renin activity most strongly predicted angiotensin II and 1-7 levels. ACE2 also predicted angiotensin 1-7 levels and ALT-S. No single factor or the combined model, however, could fully explain ACE-S. ACE2 and ACE-S trajectories in severe COVID-19 did not differ between survivors and non-survivors. In conclusion, angiotensin II was elevated in severe COVID-19 but was markedly influenced by RAS inhibitors and driven by overall RAS activation. ACE-S was significantly lower with severe COVID-19 and did not correlate with ACE concentrations. A shift to the alt-RAS axis because of increased ACE2 could partially explain the relative reduction in angiotensin II levels., (© 2022. The Author(s).)

Background: BK polyomavirus-associated nephropathy (BKPyVAN) carries a risk of irreversible allograft injury. While detection of BK viremia and biopsy assessment are the current diagnostic gold standard, the diagnostic value of biomarkers reflecting tissue injury (donor-derived cell-free DNA [dd-cfDNA]) or immune activation (C-X-C motif chemokine ligand [CXCL]9 and CXCL10) remains poorly defined., Methods: For this retrospective study, 19 cases of BKPyVAN were selected from the Vienna transplant cohort (biopsies performed between 2012 and 2019). Eight patients with T cell-mediated rejection (TCMR), 17 with antibody-mediated rejection (ABMR) and 10 patients without polyomavirus nephropathy or rejection served as controls. Fractions of dd-cfDNA were quantified using next-generation sequencing and CXCL9 and CXCL10 were detected using multiplex immunoassays., Results: BKPyVAN was associated with a slight increase in dd-cfDNA (median; interquartile range: .38% [.27%-1.2%] vs. .21% [.12%-.34%] in non-rejecting control patients; p = .005). Levels were far lower than in ABMR (1.2% [.82%-2.5%]; p = .004]), but not different from TCMR (.54% [.26%-3.56%]; p = .52). Within the BKPyVAN cohort, we found no relationship between dd-cfDNA levels and the extent of tubulo-interstitial infiltrates, BKPyVAN class and BK viremia/viruria, respectively. In some contrast to dd-cfDNA, concentrations of urinary CXCL9 and CXCL10 exceeded those detected in ABMR, but similar increases were also found in TCMR., Conclusion: BKPyVAN can induce moderate increases in dd-cfDNA and concomitant high urinary excretion of chemokines, but this pattern may be indistinguishable from that of TCMR. Our results argue against a significant value of these biomarkers to reliably distinguish BKPyVAN from rejection., (© 2022 The Authors. Clinical Transplantation published by John Wiley & Sons Ltd.)

Objectives: As part of a randomised controlled trial, this qualitative study aimed to identify experiences and challenges of hospitalised patients with COVID-19 during illness and treatment (objective 1: COVID-19-related perspectives; objective 2: trial participation-related perspectives)., Design: Semistructured interviews following a prespecified interview guide, transcribed verbatim and analysed in accordance with the grounded theory process. Investigator triangulation served to ensure rigour of the analysis., Setting: Interviews were embedded in a multicentre, randomised, active-controlled, open-label platform trial testing efficacy and safety of experimental therapeutics for patients with COVID-19 (Austrian Corona Virus Adaptive Clinical Trial)., Participants: 20 patients (60±15 years) providing 21 interviews from 8 June 2020 to 25 April 2021., Results: Qualitative data analysis revealed four central themes with subthemes. Theme 1, 'A Severe Disease', related to objective 1, was characterised by subthemes 'symptom burden', 'unpredictability of the disease course', 'fear of death' and 'long-term aftermaths with lifestyle consequences'. Theme 2, 'Saved and Burdened by Hospitalization', related to objective 1, comprised patients describing their in-hospital experience as 'safe haven' versus 'place of fear', highlighting the influence of 'isolation'. Theme 3, 'Managing One's Own Health', related to objective 1, showed how patients relied on 'self-management' and 'coping' strategies. Theme 4, 'Belief in Medical Research', related to objective 2, captured patients' 'motivation for study participation', many expressing 'information gaps' and 'situational helplessness' in response to study inclusion, while fewer mentioned 'therapy side-effects' and provided 'study reflection'. Investigator triangulation with an expert focus group of three doctors who worked at the study centre confirmed the plausibility of these results., Conclusions: Several of the identified themes (2, 3, 4) are modifiable and open for interventions to improve care of patients with COVID-19. Patient-specific communication and information is of utmost importance during clinical trial participation, and was criticised by participants of the present study. Disease self-management should be actively encouraged., Trial Registration Number: NCT04351724., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Repeated vaccination against SARS-CoV-2 increases serological response in kidney transplant recipients (KTR) with high interindividual variability. No decision support tool exists to predict SARS-CoV-2 vaccination response to third or fourth vaccination in KTR. We developed, internally and externally validated five different multivariable prediction models of serological response after the third and fourth vaccine dose against SARS-CoV-2 in previously seronegative, COVID-19-naïve KTR. Using 20 candidate predictor variables, we applied statistical and machine learning approaches including logistic regression (LR), least absolute shrinkage and selection operator (LASSO)-regularized LR, random forest, and gradient boosted regression trees. For development and internal validation, data from 590 vaccinations were used. External validation was performed in four independent, international validation cohorts comprising 191, 184, 254, and 323 vaccinations, respectively. LASSO-regularized LR performed on the whole development dataset yielded a 20- and 10-variable model, respectively. External validation showed AUC-ROC of 0.840, 0.741, 0.816, and 0.783 for the sparser 10-variable model, yielding an overall performance 0.812. A 10-variable LASSO-regularized LR model predicts vaccination response in KTR with good overall accuracy. Implemented as an online tool, it can guide decisions whether to modulate immunosuppressive therapy before additional active vaccination, or to perform passive immunization to improve protection against COVID-19 in previously seronegative, COVID-19-naïve KTR., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Osmanodja, Stegbauer, Kantauskaite, Rump, Heinzel, Reindl-Schwaighofer, Oberbauer, Benotmane, Caillard, Masset, Kerleau, Blancho, Budde, Grunow, Mikhailov, Schrezenmeier and Ronicke.)

Background: Pretransplant kidney graft biopsies have been suggested for organ quality assessment. Data on the association between donor proteinuria and organ quality of deceased donors are not available., Methods: In this prospective study, we analyzed 147 pretransplant kidney biopsies from 88 deceased adult donors procured and transplanted consecutively at the Medical University Vienna between July 2017 and May 2020. Lesions in each renal compartment were scored from 0 to 5 with each ascending score representing a 20% increase in organ damage. A chronic lesions score was calculated including glomerulosclerosis, intima fibrosis, hyalinosis, interstitial fibrosis, and tubular atrophy., Results: The median chronic lesion score was 2 (interquartile range [IQR] 1-4) and the median donor urinary protein to creatinine ratio (UPCR) was 382 mg/dL (IQR 222-703). There was a positive correlation between UPCR and number of chronic lesions (β 0.15, 95% confidence interval, 0.03-0.28; P = 0.019). Biopsies with 2 or more lesions had a median UPCR of 486 mg/dL (IQR 251-717) compared with 274 mg/dL (IQR 211-556; P = 0.016) in biopsies with <2 lesions. The risk for detection of 2 or more lesions rose by 18% for every log increase in UPCR (risk ratio 1.18, 95% confidence interval, 1.03-1.25; P = 0.017). Multivariable and sensitivity analysis revealed an independent and robust association between chronic lesions and UPCR., Conclusions: Donor UPCR is associated with chronic lesions in pretransplant deceased donor kidney graft biopsies. This finding justifies further investigation of donor proteinuria for the assessment of organ quality and outcome., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Impaired response to COVID-19 vaccination is of particular concern in immunosuppressed patients. To determine the best vaccination strategy for this vulnerable group we performed a single center, 1:1 randomized blinded clinical trial. Patients who failed to seroconvert upon two mRNA vaccinations (BNT162b2 or mRNA-1273) are randomized to receive either a third dose of the same mRNA or the vector vaccine ChAdOx1 nCoV-19. Primary endpoint is the difference in SARS-CoV-2 spike antibody seroconversion rate between vector and mRNA vaccinated patients four weeks after the third dose. Secondary outcomes include cellular immune responses. Seroconversion rates at week four are significantly higher in the mRNA (homologous vaccination, 15/24, 63%) as compared to the vector vaccine group (heterologous vaccination, 4/22, 18%). SARS-CoV-2-specific T-cell responses are reduced but could be increased after a third dose of either vector or mRNA vaccine. In a multivariable logistic regression analysis, patient age and vaccine type are associated with seroconversion. No serious adverse event is attributed to COVID-19 booster vaccination. Efficacy and safety data underline the importance of a booster vaccination and support the use of a homologous mRNA booster vaccination in immunosuppressed patients.Trial registration: EudraCT No.: 2021-002693-10., (© 2022. The Author(s).)

Objectives: Ventilator-induced lung injury (VILI) is a major contributor to morbidity and mortality in critically ill patients. Mechanical damage to the lungs is potentially aggravated by the activation of the renin-angiotensin system (RAS). This article describes RAS activation profiles in VILI and discusses the effects of angiotensin (Ang) 1-7 supplementation or angiotensin-converting enzyme (ACE) inhibition with captopril as protective strategies., Design: Animal study., Setting: University research laboratory., Subjects: C57BL/6 mice., Interventions: Anesthetized mice ( n = 12-18 per group) were mechanically ventilated with low tidal volume (LV T , 6 mL/kg), high tidal volume (HV T , 15 mL/kg), or very high tidal volume (VHV T , 30 mL/kg) for 4 hours, or killed after 3 minutes (sham). Additional VHV T groups received infusions of 60 μg/kg/hr Ang 1-7 or a single dose of 100 mg/kg captopril., Measurements and Main Results: VILI was characterized by increased bronchoalveolar lavage fluid levels of interleukin (IL)-6, keratinocyte-derived cytokine, and macrophage inflammatory protein-2 (MIP2). The Ang metabolites in plasma measured with liquid chromatography tandem mass spectrometry showed a strong activation of the classical (Ang I, Ang II) and alternative RAS (Ang 1-7, Ang 1-5), with highest concentrations found in the HV T group. Although the lung-tissue ACE messenger RNA expression was unchanged, its protein expression showed a dose-dependent increase under mechanical ventilation. The ACE2 messenger RNA expression decreased in all ventilated groups, whereas ACE2 protein levels remained unchanged. Both captopril and Ang 1-7 led to markedly increased Ang 1-7 plasma levels, decreased Ang II levels, and ACE activity (Ang II/Ang I ratio), and effectively prevented VILI., Conclusions: VILI is accompanied by a strong activation of the RAS. Based on circulating Ang metabolite levels and tissue expression of RAS enzymes, classical ACE-dependent and alternative RAS cascades were activated in the HV T group, whereas classical RAS activation prevailed with VHV T ventilation. Ang 1-7 or captopril protected from VILI primarily by modifying the systemic RAS profile., Competing Interests: Dr. Ullrich reports travel expenses and honoraria from Biotest, grants from CCORE, Bayer AG, and Biotest, holds a patent (EP 151897774, minimally invasive liquid lung) and equity in CCORE Technology, a medical device company that develops minimally invasive blood purification devices. Dr. Krenn received funding from Apeptico GmbH and Biotest GmbH. Drs. Poglitsch and Domenig are employed at Attoquant Diagnostics. Dr. Ullrich’s institution received funding from Apeptico, Bayer AG, Philips, and Biotest; he received funding from Biotest, F4 Pharma, and CCORE Technologies. The remaining authors have disclosed that they do not have any potential conflicts of interest., (Copyright © 2022 by the Society of Critical Care Medicine and Wolters Kluwer Health, Inc. All Rights Reserved.)

Response to SARS-CoV-2-vaccines in kidney-transplant recipients (KTR) is severely reduced. Heterologous3 rd vaccination combining mRNA and vector vaccines did not increase seroconversion at 4 weeks after vaccination, but evolution of antibody levels beyond the first month remains unknown. We have recently completed a randomized-controlled trial on heterologous (Ad26COVS1) vs. homologous (BNT162b2 or mRNA-1273) 3 rd vaccination in 201 KTR not developing SARS-CoV-2-spike-protein antibodies following two doses of mRNA vaccine (EurdraCT: 2021-002927-39). Here, we report seroconversion at the second follow-up at 3 months after the 3 rd vaccination (prespecified secondary endpoint). In addition, higher cut-off levels associated with neutralizing capacity and protective immunity were applied (i.e., > 15, > 100, > 141, and > 264 BAU/ml). A total of 169 patients were available for the 3-month follow-up. Overall, seroconversion at 3 months was similar between both groups (45 vs. 50% for mRNA and the vector group, respectively; p = 0.539). However, when applying higher cut-off levels, a significantly larger number of individuals in the vector group reached antibody levels > 141 and > 264 BAU/ml at the 3-month follow-up (141 BAU/ml: 4 vs. 15%, p = 0.009 and 264 BAU/ml: 1 vs. 10%, p = 0.018 for mRNA vs. the vector vaccine group, respectively). In line, antibody levels in seroconverted patients further increased from month 1 to month 3 in the vector group while remaining unchanged in the mRNA group (median increase: mRNA = 1.35 U/ml and vector = 27.6 U/ml, p = 0.004). Despite a similar overall seroconversion rate at 3 months following 3 rd vaccination in KTR, a heterologous 3rd booster vaccination with Ad26COVS1 resulted in significantly higher antibody levels in responders., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Heinzel, Schretzenmeier, Regele, Hu, Raab, Eder, Aigner, Jabbour, Aschauer, Stefanski, Dörner, Budde, Reindl-Schwaighofer and Oberbauer.)

Secondary hyperparathyroidism in chronic kidney disease poses a major risk factor for vascular calcification and high bone turnover, leading to mineralization defects. The aim was to analyze the effect of active vitamin D and calcimimetic treatment on fibroblast growth factor 23 (FGF23), serum calcification propensity (T50), a surrogate marker of calcification stress and bone specific alkaline phosphatase (BAP) in hemodialysis. This is a subanalysis of a randomized trial comparing etelcalcetide vs. alfacalcidol in 62 hemodialysis patients for 1 year. We compared the change of BAP and serum calcification propensity between the two medications and assessed the influence of FGF23 change over time. We found no significant differences in the change of BAP or serum calcification propensity (T50) levels from baseline to study end between treatment arms (difference in change of marker between treatment with etelcalcetide vs. alfacalcidol: BAP : 2.0 ng/ml [95% CI-1.5,5.4], p = 0.3; T50: -15 min [95% CI -49,19], p = 0.4). Using FGF23 change over time, we could show that BAP levels at study end were associated with FGF23 change (-0.14 [95% CI -0.21, -0.08], p < 0.001). We did not observe the same association between FGF23 change and T50 (effect of FGF23 change on T50: 3.7 [95% CI -5.1, 12], p = 0.4; R 2 = 0.07 vs. R 2 = 0.06). No significant difference was found in serum calcification propensity (T50) values between treatment arms. FGF23 was not associated with serum calcification propensity (T50), but was negatively correlated with BAP underlying its role in the bone metabolism., Clinical Trial Registration: [www.ClinicalTrials.gov], identifier [NCT03182699]., Competing Interests: RO reports grants from Amgen during the conduct of the study. In addition, RO, KD, and RR-S have a patent “Methods of treating left ventricle hypertrophy” pending. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Dörr, Hödlmoser, Kammer, Reindl-Schwaighofer, Lorenz, Reiskopf, Jagoditsch, Marculescu and Oberbauer.)

In dialysis patients the humoral response to anti-SARS-CoV-2 vaccines is attenuated and rapidly declines over time. However, data on the persistence of the immune response in peritoneal dialysis (PD) patients are scarce, particularly after a third (booster) dose with mRNA-1273 vaccine. In this prospective cohort study, we report anti-SARS-CoV-2 antibody levels in PD patients before and after the third dose of mRNA-1273 vaccine. Six months after the second dose, anti-SARS-CoV-2 antibodies were detected in all patients ( n = 34). However, within this time period antibodies substantially declined in 31 of 34 patients (4.5-fold, median = 192 BAU/mL, p = 1.27 × 10 -9 ) and increased in three patients. In accordance with government regulations, a third dose of mRNA-1273 vaccine (50 μg) was given to 27 PD patients 6 months after the second dose which induced a significant increase of anti-SARS-CoV-2 antibody titers (58.6-fold, median = 19405 BAU/mL, p = 1.24 × 10 -29 ). A mixed model analysis showed that a lower Davies Comorbidity Score and a higher GFR were associated with higher antibody titers ( p = 0.03 and p = 0.02). The most common adverse events after the third dose were pain at the injection site (77.8%) and fatigue (51.9%). No hospitalizations were reported. In conclusion, 6 months after the second dose of mRNA-1273 vaccine, anti-SARS-CoV-2 antibodies substantially decreased in PD patients, whereas a well-tolerated third dose induced a robust humoral response. Our data suggest that the administration of a booster dose within a shorter interval than 6 months should be considered in PD patients in order to maintain high anti-SARS-CoV-2 antibody levels and assure protection from severe COVID-19 disease., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Beilhack, Monteforte, Frommlet, Reindl-Schwaighofer, Strassl and Vychytil.)

Introduction: Kidney transplant recipients (KTR) are at high risk of developing severe COVID-19. However, vaccine response in this population is severely impaired with humoral response rates of 36-54 and 55-69% after two or three doses of SARS-COV-2 vaccines, respectively. Triple immunosuppression and specifically the use of anti-proliferative agents such as mycophenolic acid (MPA) or azathioprine (AZA) have been identified as risk factors for vaccine hypo-responsiveness., Methods: We hypothesized that in vaccine non-responders to at least three previous vaccine doses, pausing of MPA or AZA for 1 week before and 1 week after an additional vaccination would improve humoral response rates. We conducted an open-label, non-randomized controlled pilot study including 40 KTR with no detectable humoral response after three or four previous vaccine doses. Primary endpoint was seroconversion following SARS-CoV-2 vaccination. MPA and AZA was paused in 18 patients 1 week before until 1 week after an additional vaccine dose while immunosuppression was continued in 22 patients., Results: There was no difference in the humoral response rate between the MPA/AZA pause group and the control group (29 vs. 32%, p > 0.99). Absolute antibody levels were also not statistically significantly different between the two groups ( p = 0.716).Renal function in the MPA/AZA pause group remained stable and there was no detection of new onset donor-specific antibodies or an increase of donor-derived cell-free DNA serving as a marker of allograft damage throughout the study period., Conclusion: Pausing of MPA/AZA for 2 weeks peri-vaccination did not increase the rate of seroconversion in kidney transplant. However, one in three KTR without humoral immune response to at least three previous vaccinations developed antibodies after an additional vaccine dose supporting continued vaccination in non-responders., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Regele, Heinzel, Hu, Raab, Eskandary, Faé, Zelzer, Böhmig, Bond, Fischer, Oberbauer and Reindl-Schwaighofer.)

Background: At Eurotransplant (ET), kidneys are transferred to "rescue allocation" (RA), whenever the standard allocation (SA) algorithms Eurotransplant Kidney Allocation System (ETKAS) and Eurotransplant Senior Program (ESP) fail. We analyzed the outcome of RA., Methods: Retrospective patient clinical and demographic characteristics association analyses were performed with graft outcomes for 2422 recipients of a deceased donor renal transplantation (DDRT) after RA versus 25 481 after SA from 71 centers across all ET countries from 2006 to 2018., Results: Numbers of DDRTs after RA increased over the time, especially in Germany. RA played a minor role in ESP versus ETKAS (2.7% versus 10.4%). RA recipients and donors were older compared with SA recipients and donors, cold ischemia times were longer, waiting times were shorter, and the incidence of primary nonfunction was comparable. Among ETKAS recipients, HLA matching was more favorable in SA (mean 3.7 versus 2.5). In multivariate modeling, the incidence of graft loss in ETKAS recipients was reduced in RA compared with SA (subdistribution hazard ratio, 0.80; 95% confidence interval [0.70-0.91], P < 0.001), whereas other outcomes (mortality, death with functioning graft (DwFG)) were not significantly different. None of the 3 outcomes were significantly different when comparing RA with SA within the ESP program., Conclusions: Facing increased waiting times and mortality on dialysis due to donor shortage, this study reveals encouragingly positive DDRT outcomes following RA. This supports the extension of RA to more patients and as an alternative tool to enable transplantation in patients in countries with prohibitively long waiting times or at risk of deterioration., Competing Interests: The authors declare no funding or conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

Fibroblast growth factor 23 (FGF23) is elevated in patients with chronic kidney disease and contributes to left ventricular hypertrophy (LVH). The aim of the analysis was to determine whether this effect is mediated by the renin-angiotensin-aldosterone system (RAAS) in hemodialysis. Serum samples from 62 randomized hemodialysis patients with LVH were analyzed for plasma renin activity (PRA-S), angiotensin II (AngII), and metabolites, angiotensin-converting enzyme-2 (ACE2) and aldosterone using a high throughput mass spectrometry assay. Compared to healthy individuals, levels of the RAAS parameters PRA-S, AngII and aldosterone were generally lower [median (IQR) PRA-S 130 (46-269) vs. 196 (98, 238) pmol/L; AngII 70 (28-157) vs. 137 (76, 201) pmol/L; Aldosterone 130 (54, 278) vs. 196 (98, 238) pmol/L]. We did not find an indication that the effect of FGF23 on LVH was mediated by RAAS parameters, with all estimated indirect effects virtually zero. Furthermore, FGF23 was not associated with RAAS parameter levels throughout the study. While there was a clear association between FGF23 levels and left ventricular mass index (LVMI) at the end of the study and in the FGF23 fold change and LVMI change analysis, no association between RAAS and LVMI was observed. Serum concentrations of PRA-S, AngII, and aldosterone were below the ranges measured in healthy controls suggesting that RAAS is not systemically activated in hemodialysis patients. The effect of FGF23 on LVMI was not mediated by systemic RAAS activity. These findings challenge the current paradigm of LVH progression and treatment with RAAS blockers in dialysis., Clinical Trial Registration: [https://clinicaltrials.gov/ct2/show/NCT03182699], identifier [NCT03182699]., Competing Interests: RO reported grants from Amgen during the conduct of the study. In addition, RO, KD, and RR-S had a patent “Methods of treating left ventricle hypertrophy” pending. MP was employed by Attoquant Diagnostics. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Dörr, Kammer, Reindl-Schwaighofer, Lorenz, Marculescu, Poglitsch, Beitzke and Oberbauer.)

Background: Late antibody-mediated rejection (ABMR) after kidney transplantation is a major cause of long-term allograft loss with currently no proven treatment strategy. Design for trials testing treatment for late ABMR poses a major challenge as hard clinical endpoints require large sample sizes. We performed a retrospective cohort study applying commonly used selection criteria to evaluate the slope of the estimated glomerular filtration rate (eGFR) within an early and short timeframe after biopsy as a surrogate of future allograft loss for clinical trials addressing late ABMR., Methods: Study subjects were identified upon screening of the Vienna transplant biopsy database. Main inclusion criteria were (i) a solitary kidney transplant between 2000 and 2013, (ii) diagnosis of ABMR according to the Banff 2015 scheme at >12 months post-transplantation, (iii) age 15-75 years at ABMR diagnosis, (iv) an eGFR > 25 mL/min/1.73 m 2 at ABMR diagnosis, and (v) a follow-up for at least 36 months after ABMR diagnosis. The primary outcome variable was death-censored graft survival. A mixed effects model with linear splines was used for eGFR slope modeling and association of graft failure and eGFR slope was assessed applying a multivariate competing risk analysis with landmarks set at 12 and 24 months after index biopsy., Results: A total of 70 allografts from 68 patients were included. An eGFR loss of 1 ml/min/1.73 m 2 per year significantly increased the risk for allograft failure, when eGFR slopes were modeled over 12 months [HR 1.1 (95% CI: 1.01-1.3), p = 0.020] or over 24 months [HR 1.3 (95% CI: 1.1-1.4), p = 0.001] after diagnosis of ABMR with landmarks set at both time points. Covariables influencing graft loss in all models were histologic evidence of glomerulonephritis concurring with ABMR as well as the administration of anti-thymocyte globulin (ATG) at the time of transplantation., Conclusion: Our study supports the use of the eGFR slope modeled for at least 12 months after biopsy-proven diagnosis of late ABMR, as a surrogate parameter for future allograft loss. The simultaneous occurrence of glomerulonephritis together with ABMR at index biopsy and the use of ATG at the time of transplantation-likely representing a confounder in pre-sensitized recipients-were strongly associated with worse transplant outcomes., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Borski, Kainz, Kozakowski, Regele, Kläger, Strassl, Fischer, Faé, Wenda, Kikić, Bond, Reindl-Schwaighofer, Mayer, Eder, Wahrmann, Haindl, Doberer, Böhmig and Eskandary.)

The assessment of systemic corticosteroid effects on intrapulmonary disease biomarkers is challenging. This retrospective evaluation of a human endotoxemia model quantified ACE2 and fibrin degradation product (FDP) concentrations in bronchoalveolar lavage fluid (BALF) samples from a randomized, double-blind, placebo-controlled study (NCT01714427). Twenty-four healthy volunteers received either 2 × 40 mg intravenous dexamethasone or placebo. These doses were administered 12 h apart prior to bronchoscopy-guided intrabronchial lipopolysaccharide (LPS) stimulation (control: saline into the contralateral lung segment). We quantified ACE2 concentration, the Angiotensin-II-to-Angiotensin-1-7 conversion rate as well as FDP in BALF 6 h after LPS instillation. In placebo-treated subjects, LPS instillation increased ACE2 concentrations compared to unstimulated lung segments [1,481 (IQR: 736-1,965) vs. 546 (413-988) pg/mL; p = 0.016]. Dexamethasone abolished the increase in ACE2 concentrations (p=0.13). Accordingly, LPS instillation increased the Angiotensin-II-to-Angiotensin-1-7 conversion capacity significantly in the placebo cohort, indicating increased enzymatic activity ( p = 0.012). FDP increased following LPS-instillation [8.9 (2.7-12.2) vs. 6.6 (0.9-9.6) ng/mL, p = 0.025] in the placebo group, while dexamethasone caused a shut-down of fibrinolysis in both lung segments. LPS instillation increased ACE2 concentration, its enzymatic activity and FDP, which was mitigated by systemic dexamethasone treatment. Our results strengthen previously published findings regarding the efficiency of corticosteroids for the treatment of COVID-19-induced acute lung injury., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Reindl-Schwaighofer, Eskandary, Bartko, Heinzel, Jilma, Hecking and Schoergenhofer.)

Background: Pre-sensitized kidney transplant recipients have a higher risk for rejection following kidney transplantation and therefore receive lymphodepletional induction therapy with anti-human T-lymphocyte globulin (ATLG) whereas non-sensitized patients are induced in many centers with basiliximab. The time course of lymphocyte reconstitution with regard to the overall and donor-reactive T-cell receptor (TCR) specificity remains elusive., Methods/design: Five kidney transplant recipients receiving a 1.5-mg/kg ATLG induction therapy over 7 days and five patients with 2 × 20 mg basiliximab induction therapy were longitudinally monitored. Peripheral mononuclear cells were sampled pre-transplant and within 1, 3, and 12 months after transplantation, and their overall and donor-reactive TCRs were determined by next-generation sequencing of the TCR beta CDR3 region. Overall TCR repertoire diversity, turnover, and donor specificity were assessed at all timepoints., Results: We observed an increase in the donor-reactive TCR repertoire after transplantation in patients, independent of lymphocyte counts or induction therapy. Donor-reactive CD4 T-cell frequency in the ATLG group increased from 1.14% + -0.63 to 2.03% + -1.09 and from 0.93% + -0.63 to 1.82% + -1.17 in the basiliximab group in the first month. Diversity measurements of the entire T-cell repertoire and repertoire turnover showed no statistical difference between the two induction therapies. The difference in mean clonality between groups was 0.03 and 0.07 pre-transplant in the CD4 and CD8 fractions, respectively, and was not different over time (CD4: F(1.45, 11.6) = 0.64 p = 0.496; CD8: F(3, 24) = 0.60 p = 0.620). The mean difference in R20, a metric for immune dominance, between groups was -0.006 in CD4 and 0.001 in CD8 T-cells and not statistically different between the groups and subsequent timepoints (CD4: F(3, 24) = 0.85 p = 0.479; CD8: F(1.19, 9.52) = 0.79 p = 0.418)., Conclusion: Reduced-dose ATLG induction therapy led to an initial lymphodepletion followed by an increase in the percentage of donor-reactive T-cells after transplantation similar to basiliximab induction therapy. Furthermore, reduced-dose ATLG did not change the overall TCR repertoire in terms of a narrowed or skewed TCR repertoire after immune reconstitution, comparable to non-depletional induction therapy., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Aschauer, Jelencsics, Hu, Gregorich, Reindl-Schwaighofer, Wenda, Wekerle, Heinzel and Oberbauer.)

Importance: Fewer than 50% of kidney transplant recipients (KTRs) develop antibodies against the SARS-CoV-2 spike protein after 2 doses of an mRNA vaccine. Preliminary data suggest that a heterologous vaccination, combining mRNA and viral vector vaccines, may increase immunogenicity., Objective: To assess the effectiveness of a third dose of an mRNA vs a vector vaccine in KTRs who did not have antibodies against the SARS-CoV-2 spike protein after 2 doses of an mRNA vaccine., Design, Setting, and Participants: This was a single center, single-blinded, 1:1 randomized clinical trial of a third dose of vaccine against SARS-CoV-2, conducted from June 15 to August 16, 2021, in 201 KTRs who had not developed SARS-CoV-2 spike protein antibodies after 2 doses of an mRNA vaccine. Data analyses were performed from August 17 to August 31, 2021., Interventions: mRNA (BNT162b2 or mRNA-1273) or vector (Ad26COVS1) as a third dose of a SARS-CoV-2 vaccine., Main Outcomes and Measures: The primary study end point was seroconversion after 4 weeks (29-42 days) following the third vaccine dose. Secondary end points included neutralizing antibodies and T-cell response assessed by interferon-γ release assays (IGRA). In addition, the association of patient characteristics and vaccine response was assessed using logistic regression, and the reactogenicity of the vaccines was compared., Results: Among the study population of 197 kidney transplant recipients (mean [SD] age, 61.2 [12.4] years; 82 [42%] women), 39% developed SARS-CoV-2 antibodies after the third vaccine. There was no statistically significant difference between groups, with an antibody response rate of 35% and 42% for the mRNA and vector vaccines, respectively. Only 22% of seroconverted patients had neutralizing antibodies. Similarly, T-cell response assessed by IGRA was low with only 17 patients showing a positive response after the third vaccination. Receiving nontriple immunosuppression (odds ratio [OR], 3.59; 95% CI, 1.33-10.75), longer time after kidney transplant (OR, 1.44; 95% CI, 1.15-1.83, per doubling of years), and torque teno virus plasma levels (OR, 0.92; 95% CI, 0.88-0.96, per doubling of levels) were associated with vaccine response. The third dose of an mRNA vaccine was associated with a higher frequency of local pain at the injection site compared with the vector vaccine, while systemic symptoms were comparable between groups., Conclusions and Relevance: This randomized clinical trial found that 39% of KTRs without an immune response against SARS-CoV-2 after 2 doses of an mRNA vaccine developed antibodies against the SARS-CoV-2 spike protein 4 weeks after a third dose of an mRNA or a vector vaccine. The heterologous vaccination strategy with a vector-based vaccine was well tolerated and safe but not significantly better than the homologous mRNA-based strategy., Trial Registration: EudraCT Identifier: 2021-002927-39.

Background: Next-generation sequencing (NGS) is nowadays the most used high-throughput technology for DNA sequencing. Among others NGS enables the in-depth analysis of immune repertoires. Research in the field of T cell receptor (TCR) and immunoglobulin (IG) repertoires aids in understanding immunological diseases. A main objective is the analysis of the V(D)J recombination defining the structure and specificity of the immune repertoire. Accurate processing, evaluation and visualization of immune repertoire NGS data is important for better understanding immune responses and immunological behavior., Results: ImmunoDataAnalyzer (IMDA) is a pipeline we have developed for automatizing the analysis of immunological NGS data. IMDA unites the functionality from carefully selected immune repertoire analysis software tools and covers the whole spectrum from initial quality control up to the comparison of multiple immune repertoires. It provides methods for automated pre-processing of barcoded and UMI tagged immune repertoire NGS data, facilitates the assembly of clonotypes and calculates key figures for describing the immune repertoire. These include commonly used clonality and diversity measures, as well as indicators for V(D)J gene segment usage and between sample similarity. IMDA reports all relevant information in a compact summary containing visualizations, calculations, and sample details, all of which serve for a more detailed overview. IMDA further generates an output file including key figures for all samples, designed to serve as input for machine learning frameworks to find models for differentiating between specific traits of samples., Conclusions: IMDA constructs TCR and IG repertoire data from raw NGS reads and facilitates descriptive data analysis and comparison of immune repertoires. The IMDA workflow focus on quality control and ease of use for non-computer scientists. The provided output directly facilitates the interpretation of input data and includes information about clonality, diversity, clonotype overlap as well as similarity, and V(D)J gene segment usage. IMDA further supports the detection of sample swaps and cross-sample contamination that potentially occurred during sample preparation. In summary, IMDA reduces the effort usually required for immune repertoire data analysis by providing an automated workflow for processing raw NGS data into immune repertoires and subsequent analysis. The implementation is open-source and available on https://bioinformatics.fh-hagenberg.at/immunoanalyzer/ ., (© 2021. The Author(s).)

Background and Objectives: The median kidney transplant half-life is 10-15 years. Because of the scarcity of donor organs and immunologic sensitization of candidates for retransplantation, there is a need for quantitative information on if and when a second transplantation is no longer associated with a lower risk of mortality compared with waitlisted patients treated by dialysis. Therefore, we investigated the association of time on waiting list with patient survival in patients who received a second transplantation versus remaining on the waiting list., Design, Setting, Participants, & Measurements: In this retrospective study using target trial emulation, we analyzed data of 2346 patients from the Austrian Dialysis and Transplant Registry and Eurotransplant with a failed first graft, aged over 18 years, and waitlisted for a second kidney transplantation in Austria during the years 1980-2019. The differences in restricted mean survival time and hazard ratios for all-cause mortality comparing the treatment strategies "retransplant" versus "remain waitlisted with maintenance dialysis" are reported for different waiting times after first graft loss., Results: Second kidney transplantation showed a longer restricted mean survival time at 10 years of follow-up compared with remaining on the waiting list (5.8 life months gained; 95% confidence interval, 0.9 to 11.1). This survival difference was diminished in patients with longer waiting time after loss of the first allograft; restricted mean survival time differences at 10 years were 8.0 (95% confidence interval, 1.9 to 14.0) and 0.1 life months gained (95% confidence interval, -14.3 to 15.2) for patients with waiting time for retransplantation of <1 and 8 years, respectively., Conclusions: Second kidney transplant is associated with patient survival compared with remaining waitlisted and treatment by dialysis, but the survival difference diminishes with longer waiting time., (Copyright © 2022 by the American Society of Nephrology.)

Background: Antigen recognition of allo-peptides and HLA molecules leads to the activation of donor-reactive T-cells following transplantation, potentially causing T-cell-mediated rejection (TCMR). Sequencing of the T-cell receptor (TCR) repertoire can be used to track the donor-reactive repertoire in blood and tissue of patients after kidney transplantation., Methods/design: In this prospective cohort study, 117 non-sensitized kidney transplant recipients with anti-CD25 induction were included. Peripheral mononuclear cells (PBMCs) were sampled pre-transplant and at the time of protocol or indication biopsies together with graft tissue. Next-generation sequencing (NGS) of the CDR3 region of the TCRbeta chain was performed after donor stimulation in mixed lymphocyte reactions to define the donor-reactive TCR repertoire. Blood and tissue of six patients experiencing a TCMR and six patients without rejection on protocol biopsies were interrogated for these TCRs. To elucidate common features of T-cell clonotypes, a network analysis of the TCR repertoires was performed., Results: After transplantation, the frequency of circulating donor-reactive CD4 T-cells increased significantly from 0.86 ± 0.40% to 2.06 ± 0.40% of all CD4 cells (p < 0.001, mean dif.: -1.197, CI: -1.802, -0.593). The number of circulating donor-reactive CD4 clonotypes increased from 0.72 ± 0.33% to 1.89 ± 0.33% (p < 0.001, mean dif.: -1.168, CI: -1.724, -0.612). No difference in the percentage of donor-reactive T-cells in the circulation at transplant biopsy was found between subjects experiencing a TCMR and the control group [p = 0.64 (CD4 + ), p = 0.52 (CD8 + )]. Graft-infiltrating T-cells showed an up to six-fold increase of donor-reactive T-cell clonotypes compared to the blood at the same time (3.7 vs. 0.6% and 2.4 vs. 1.5%), but the infiltrating TCR repertoire was not reflected by the composition of the circulating TCR repertoire despite some overlap. Network analysis showed a distinct segregation of the donor-reactive repertoire with higher modularity than the overall TCR repertoire in the blood. These findings indicate an unchoreographed process of diverse T-cell clones directed against numerous non-self antigens found in the allograft., Conclusion: Donor-reactive T-cells are enriched in the kidney allograft during a TCMR episode, and dominant tissue clones are also found in the blood., Trial Registration: Clinicaltrials.gov: NCT: 03422224 (https://clinicaltrials.gov/ct2/show/NCT03422224)., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Aschauer, Jelencsics, Hu, Heinzel, Gregorich, Vetter, Schaller, Winkler, Weinberger, Pimenov, Gualdoni, Eder, Kainz, Troescher, Regele, Reindl-Schwaighofer, Wekerle, Huppa, Sykes and Oberbauer.)

Purpose: AT04A and AT06A are two AFFITOPE® peptide vaccine candidates being developed for the treatment of hypercholesterolemia by inducing proprotein convertase subtilisin/kexin type 9 (PCSK9)-specific antibodies. This study aimed to investigate safety, tolerability, antibody development, and reduction of low-density lipoprotein cholesterol (LDLc) following four subcutaneous immunizations., Methods: This phase I, single-blind, randomized, placebo-controlled study was conducted in a total of 72 healthy subjects with a mean fasting LDLc level at baseline of 117.1 mg/dL (range 77-196 mg/dL). Each cohort enrolled 24 subjects to receive three priming immunizations at weeks 0, 4, and 8 and to receive a single booster immunization at week 60 of either AT04A, AT06A, or placebo. In addition to safety (primary objective), the antigenic peptide- and PCSK9-specific antibody response and the impact on LDLc were evaluated over a period of 90 weeks., Results: The most common systemic treatment-related adverse events (AEs) reported were fatigue, headache, and myalgia in 75% of subjects in the AT06A group and 58% and 46% of subjects in the placebo and AT04A groups, respectively. Injection site reactions (ISR) representing 63% of all treatment-emergent adverse events (TEAEs), were transient and mostly of mild or moderate intensity and rarely severe (3%). Both active treatments triggered a robust, long-lasting antibody response towards the antigenic peptides used for immunization that optimally cross-reacted with the target epitope on PCSK9. In the AT04A group, a reduction in serum LDLc was observed with a mean peak reduction of 11.2% and 13.3% from baseline compared to placebo at week 20 and 70 respectively, and over the whole study period, the mean LDLc reduction for the AT04A group vs. placebo was -7.2% (95% CI [-10.4 to -3.9], P < 0.0001). In this group, PCSK9 target epitope titers above 50 were associated with clinically relevant LDLc reductions with an individual maximal decrease of 39%., Conclusions: Although both AT04A and AT06 were safe and immunogenic, only AT04A demonstrated significant LDLc-lowering activity, justifying further development., Trial Registration: EudraCT: 2015-001719-11. ClinicalTrials.gov Identifier: NCT02508896., (© 2021. The Author(s).)

Background: Nonpathogenic torque teno viruses (TTVs) are highly prevalent in transplant recipients and associated with immunosuppression. Studies in kidney transplant patients have proposed assessment of TTV load for risk stratification of clinically overt graft rejection. The value of TTV quantification in the context of subclinical rejection has not been evaluated., Methods: In this prospective trial, 307 consecutive kidney transplant recipients were subjected to per-protocol monitoring of plasma TTV. TTV was analyzed in the context of protocol biopsies (n = 82), scheduled 1 year posttransplantation., Results: TTV load at the time of biopsy was lower in recipients with rejection (n = 19; according to Banff, including borderline changes suspicious for acute T cell-mediated rejection) than those without rejection (n = 63) whereby each log increase in TTV copies/mL decreased the risk for rejection by 9% (risk ratio 0.91, 95% confidence interval, 0.85-0.97; P = 0.004). Development of chronic lesions (cg, cv, ci, ct, ah, ptcml) was associated with the number of days with a TTV load <1 × 106 copies/mL between months 3 and 12 posttransplant (β 0.07, 95% confidence interval, 0.01-0.14; P = 0.02)., Conclusions: This trial demonstrates an association between TTV and subclinical graft rejection in kidney transplant recipients. A TTV load <1 × 106 copies/mL suggests suboptimal immunosuppression., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc.)

Circulating donor-specific antibodies (DSA) do not necessarily indicate antibody-mediated rejection (ABMR). Here, we evaluated the diagnostic value of donor-derived cell-free DNA (dd-cfDNA) as an add-on to DSA detection. The study included two independent cohorts of DSA + kidney allograft recipients, 45 subclinical cases identified by cross-sectional antibody screening (cohort 1), and 30 recipients subjected to indication biopsies (cohort 2). About 50% of the DSA + recipients had ABMR and displayed higher dd-cfDNA levels than DSA + ABMR - recipients (cohort 1: 1.90% [median; IQR: 0.78-3.90%] vs. 0.52% [0.35-0.72%]; P < 0.001); (cohort 2: 1.20% [0.82-2.50%] vs. 0.59% [0.28-2.05%]; P = 0.086). Receiver operating characteristic (ROC) analysis revealed an area under the curve (AUC) of 0.89 and 0.69 for dd-cfDNA, and 0.88 and 0.77 for DSA mean fluorescence intensity (MFI), respectively. In combined models, adding dd-cfDNA to DSA-MFI or vice versa significantly improved the diagnostic accuracy. Limited diagnostic performance of dd-cfDNA in cohort 2 was related to the frequent finding of other types of graft injury among ABMR - recipients, like T cell-mediated rejection or glomerulonephritis. For dd-cfDNA in relation to injury of any cause an AUC of 0.97 was calculated. Monitoring of dd-cfDNA in DSA + patients may be a useful tool to detect ABMR and other types of injury., (© 2021 The Authors. Transplant International published by John Wiley & Sons Ltd on behalf of Steunstichting ESOT.)

Background and Objectives: In patients with kidney failure due to IgA nephropathy, IgA deposits can recur in a subsequent kidney transplant. The incidence, effect, and risk factors of IgA nephropathy recurrence is unclear, because most studies have been single center and sample sizes are relatively small., Design, Setting, Participants, & Measurements: We performed a multicenter, international, retrospective study to determine the incidence, risk factors, and treatment response of recurrent IgA nephropathy after kidney transplantation. Data were collected from all consecutive patients with biopsy-proven IgA nephropathy transplanted between 2005 and 2015, across 16 "The Post-Transplant Glomerular Disease" study centers in Europe, North America, and South America., Results: Out of 504 transplant recipients with IgA nephropathy, recurrent IgA deposits were identified by kidney biopsy in 82 patients; cumulative incidence of recurrence was 23% at 15 years (95% confidence interval, 14 to 34). Multivariable Cox regression revealed a higher risk for recurrence of IgA deposits in patients with a pre-emptive kidney transplant (hazard ratio, 3.45; 95% confidence interval, 1.31 to 9.17) and in patients with preformed donor-specific antibodies (hazard ratio, 2.59; 95% confidence interval, 1.09 to 6.19). After kidney transplantation, development of de novo donor-specific antibodies was associated with subsequent higher risk of recurrence of IgA nephropathy (hazard ratio, 6.65; 95% confidence interval, 3.33 to 13.27). Immunosuppressive regimen was not associated with recurrent IgA nephropathy in multivariable analysis, including steroid use. Graft loss was higher in patients with recurrence of IgA nephropathy compared with patients without (hazard ratio, 3.69; 95% confidence interval, 2.04 to 6.66), resulting in 32% (95% confidence interval, 50 to 82) graft loss at 8 years after diagnosis of recurrence., Conclusions: In our international cohort, cumulative risk of IgA nephropathy recurrence increased after transplant and was associated with a 3.7-fold greater risk of graft loss., (Copyright © 2021 by the American Society of Nephrology.)

Background: Glomerulonephritis (GN), including post-transplant IgAN (post-Tx IgAN) is an important contributor to decreased long-term allograft survival. The immunopathological detection of the complement degradation product C4d in glomeruli (C4dG) has been recently described as a risk factor in native kidney IgAN, however little is known about C4dG deposition in post-Tx IgAN. We hypothesized that glomerular C4d may indicate a more aggressive disease course and worse allograft survival in patients with post-Tx IgAN., Methods: In this retrospective study we assessed the presence and clinical relevance of C4dG in patients with post-transplant IgAN. We analyzed 885 renal allograft recipients, including 84 patients with post-transplant GN. All patients were transplanted between January 1999 and April 2006 and underwent at least one biopsy for differnt causes. The primary endpoint was death-censored graft survival, with a median follow-up of 9.6 (IQR 3.8-13.2) years., Results: The prevalence of post-Tx GN was 9.5%. Twenty-seven patients with post-Tx IgAN were included. C4dG positive patients (N = 18, 66.7%) had significantly worse allograft survival compared to C4dG negative post-Tx IgAN patients and patients without post-Tx IgAN [C4dG positive: 27.8% vs. 55.6% and 66.0%; log-rank: p = 0.01]. C4dG remained a significant risk factor (HR 2.22, 95% CI 1.27-3.87) for allograft loss even after adjustment for T cell mediated rejection (TCMR) and antibody mediated rejection., Conclusion: Glomerular C4d deposition is an independent risk factor for worse graft-survival in patients with post-Tx IgAN, even after adjusting for other risk factors such as antibody mediated rejection.  Assessment of glomerular C4d deposition may provide a valuable prognostic risk assessment tool to identify high risk patients in post-Tx IgAN.

[Figure: see text].