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Seroconversion after COVID-19 vaccination is impaired in kidney transplant recipients. Emerging variants of concern such as the B.1.617.2 (delta) and the B.1.1.529 (omicron) variants pose an increasing threat to these patients. In this observational cohort study, we measured anti-S1 IgG, surrogate neutralizing, and anti-receptor-binding domain antibodies three weeks after a third mRNA vaccine dose in 49 kidney transplant recipients and compared results to 25 age-matched healthy controls. In addition, vaccine-induced neutralization of SARS-CoV-2 wild-type, the B.1.617.2 (delta), and the B.1.1.529 (omicron) variants was assessed using a live-virus assay. After a third vaccine dose, anti-S1 IgG, surrogate neutralizing, and anti-receptor-binding domain antibodies were significantly lower in kidney transplant recipients compared to healthy controls. Only 29/49 (59%) sera of kidney transplant recipients contained neutralizing antibodies against the SARS-CoV-2 wild-type or the B.1.617.2 (delta) variant and neutralization titers were significantly reduced compared to healthy controls (p < 0.001). Vaccine-induced cross-neutralization of the B.1.1.529 (omicron) variants was detectable in 15/35 (43%) kidney transplant recipients with seropositivity for anti-S1 IgG, surrogate neutralizing, and/or anti-RBD antibodies. Neutralization of the B.1.1.529 (omicron) variants was significantly reduced compared to neutralization of SARS-CoV-2 wild-type or the B.1.617.2 (delta) variant for both, kidney transplant recipients and healthy controls (p < .001 for all)., Dietmar Hopp Stiftung; Heidelberg Faculty of Medicine Rahel Goitein-Straus Program; Heidelberg Faculty of Medicine Physician Scientist Program; German Federal Research Network Applied Surveillance and Testing (BFAST); Network University Medicine; Helmholtz Association Initiative and Networking Fund Project Virological and Immunological Determinants of COVID-19 Pathogenesis

Background and objectives: antibody response after severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) vaccination is impaired in kidney transplant recipients. Emerging variants, such as B.1.617.2 ( d), are of particular concern because of their higher transmissibility and partial immune escape. Little is known about protection against these variants in immunocompromised patients. Design, setting, participants, and measurements: in this prospective two-center study, antispike 1 IgG and surrogate neutralizing antibodies were measured in 173 kidney transplant recipients and 166 healthy controls with different vaccination schedules. In addition, different SARS-CoV-2 epitope antibodies from 135 vaccinated kidney transplant recipients were compared with antibodies in 25 matched healthy controls after second vaccination. In 36 kidney transplant recipients with seroconversion, neutralization against B.1.1.7 ( a), B.1.351 ( b), and B.1.617.2 ( d) was determined on VeroE6 cells and compared with neutralization in 25 healthy controls. Results: kidney transplant recipients had significantly lower seroconversion rates compared with healthy controls. After the second vaccination, antispike 1, antireceptor-binding domain, and surrogate neutralizing antibodies were detectable in 30%, 27%, and 24% of kidney transplant recipients, respectively. This compares with 100%, 96%, and 100% in healthy controls, respectively (P,0.001). Neutralization against B.1.1.7 was detectable in all kidney transplant recipients with seroconversion, with a median serum dilution that reduces infection of cells by 50% of 80 (interquartile range, 80-320). In contrast, only 23 of 36 (64%) and 24 of 36 (67%) kidney transplant recipients showed neutralization against B.1.351 and B.1.617.2, respectively, with median serum dilutions that reduce infection of cells by 50% of 20 (interquartile range, 0-40) and 20 (interquartile range, 0-40), respectively. Neutralization against different variants was significantly higher in healthy controls (P,0.001), with all patients showing neutralization against all tested variants. Conclusions: seroconverted kidney transplant recipients show impaired neutralization against emerging variants of concern after standard two-dose vaccination., Dietmar Hopp Stiftung; German Federal Research Network Applied Surveillance and Testing; Network University Medicine; fightCOVID@DKFZ Initiative; Helmholtz Association Initiative and Networking Fund Project Virological and Immunological Determinants of COVID-19 Pathogenesis; Lessons to Get Prepared for Future Pandemics; Heidelberg Faculty of Medicine Rahel Goitein-Strauss Program; Heidelberg Faculty of Medicine Physician Scientist Program

The impaired immune response to coronavirus disease 2019 (COVID-19) vaccination in kidney transplant recipients (KTRs) leads to an urgent need for adapted immunization strategies.Sixty-nine KTRs without seroconversion after ≥3 COVID-19 vaccinations were enrolled, and humoral response was determined after an additional full-dose mRNA-1273 vaccination by measuring severe acute respiratory syndrome coronavirus 2-specific antibodies and neutralizing antibody activity against the Delta and Omicron variants 1 and 3 mo postvaccination. T-cell response was analyzed 3 mo postvaccination by assessing interferon-γ release. Mycophenolic acid (MPA) was withdrawn in 41 KTRs 1 wk before until 4 wk after vaccination to evaluate effects on immunogenicity. Graft function, changes in donor-specific anti-HLA antibodies, and donor-derived cell-free DNA were monitored in KTRs undergoing MPA withdrawal.Humoral response to vaccination was significantly stronger in KTRs undergoing MPA withdrawal 1 mo postvaccination; however, overall waning humoral immunity was noted in all KTRs 3 mo after vaccination. Higher anti-S1 immunoglobulin G levels correlated with better neutralizing antibody activity against the Delta and Omicron variants, whereas no significant association was detected between T-cell response and neutralizing antibody activity. No rejection occurred during study, and graft function remained stable in KTRs undergoing MPA withdrawal. In 22 KTRs with Omicron variant breakthrough infections, neutralizing antibody activity was better against severe acute respiratory syndrome coronavirus 2 wild-type and the Delta variants than against the Omicron variant.MPA withdrawal to improve vaccine responsiveness should be critically evaluated because withdrawing MPA may be associated with enhanced alloimmune response, and the initial effect of enhanced seroconversion rates in KTRs with MPA withdrawal disappears 3 mo after vaccination.

Introduction: donor-derived modified immune cells (MIC) induced long-term specific immunosuppression against the allogeneic donor in preclinical models of transplantation. In a phase I clinical trial (TOL-1 Study), MIC treatment resulted in a cellular phenotype that was directly and indirectly suppressive to the recipient's immune system allowing for reduction of conventional immunosuppressive therapy. Here, we describe a protocol for a randomised controlled, multicentre phase-IIb clinical trial of individualised immunosuppression with intravenously administered donor MIC compared with standard-of-care (SoC) in living donor kidney transplantation (TOL-2 Study). Methods and analysis: sixty-three living donor kidney transplant recipients from six German transplant centres are randomised 2:1 to treatment with MIC (MIC group, N=42) or no treatment with MIC (control arm, N=21). MIC are manufactured from donor peripheral blood mononuclear cells under Good Manufacturing Practice conditions. The primary objective of this trial is to determine the efficacy of MIC treatment together with reduced conventional immunosuppressive therapy in terms of achieving an operational tolerance-like phenotype compared with SoC 12 months after MIC administration. Key secondary endpoints are the number of patient-relevant infections as well as a composite of biopsy-proven acute rejection, graft loss, graft dysfunction or death. Immunosuppressive therapy of MIC-treated patients is reduced during follow-up under an extended immunological monitoring including human leucocyte antigen-antibody testing, and determination of lymphocyte subsets, for example, regulatory B lymphocytes (Breg) and antidonor T cell response. A Data Safety Monitoring Board has been established to allow an independent assessment of safety and efficacy. Ethics and dissemination: ethical approval has been provided by the Ethics Committee of the Medical Faculty of the University of Heidelberg, Heidelberg, Germany (AFmu-580/2021, 17 March 2022) and from the Federal Institute for Vaccines and Biomedicines, Paul-Ehrlich-Institute, Langen, Germany (Vorlage-Nr. 4586/02, 21 March 2022). Written informed consent will be obtained from all patients and respective donors prior to enrolment in the study. The results from the TOL-2 Study will be published in peer-reviewed medical journals and will be presented at symposia and scientific meetings. Trial registration number NCT05365672., Preparation of the study was funded by the Federal Ministry of Education and Research, Berlin, Germany (FKZ 161B0560A, 161B0560B, and FKZ 031B0560A, 031B0560B), and TolerogenixX GmbH, Heidelberg, Germany (N/A). Conduct of the study is funded by TolerogenixX GmbH (N/A).

An imbalance between CD4+-regulatory T-cells (Tregs) and CD4+-responder T-cells (Tresps) correlates with active disease flares in systemic lupus erythematosus (SLE) patients. Both cell subsets consist of highly proliferating Tregs/Tresps expressing inducible T-cell co-stimulatory molecule (ICOS) and less proliferating ICOS--Tregs/Tresps.Six-colour-flow-cytometric analysis was used to examine the effect of ICOS+- and ICOS--Treg/Tresp cell differentiation on the composition of the total CD4+-T-helper cell pool with ICOS+- and ICOS--Tregs/Tresps. Functionality of Tregs was examined using suppression assays.In 83 healthy volunteers, the ratio of ICOS+-Tregs/ICOS+-Tresps increased significantly with age, while that of ICOS--Tregs/ICOS--Tresps did not change. In 86 SLE patients (SLEDAI7), disease activity was associated with an age-independently increased ratio of both ICOS+-Tregs/ICOS+-Tresps and ICOS--Tregs/ICOS--Tresps. In these patients, the functional activity of ICOS+-Tregs, but not of ICOS--Tregs, was preserved. In 13 markedly active disease patients (SLEDAI7), the percentage of both ICOS+-Tregs and ICOS+-Tresps, was strongly increased within total CD4+-T-helper cells. However, the increased ratio of ICOS+-Tregs/ICOS+-Tresps was not maintained in these patients, due to terminal differentiation and accumulation of naïve cells within total ICOS+-Tregs. Despite increased differentiation of both ICOS--Tregs and ICOS--Tresps, the percentage of ICOS--Tregs increased within CD4+-T-helper cells, while that of ICOS--Tresps decreased, resulting in a significantly increased ratio of ICOS--Tregs/ICOS--Tresps independent of age.Our data reveal a crucial role of Treg immune senescence for the occurrence of disease flares in SLE patients, with ICOS+-Treg cells being most affected.

Eine spontane oder operationale Toleranz ist ein in der Natur selten vorkommendes Phanomen. Durch die Etablierung eines dauerhaften „kunstlichen“ Chimarismus bei einem Transplantatempfanger kann eine Toleranz gegen den spezifischen Spender jedoch zuverlassig etabliert werden. Dies geschieht allerdings zum Preis einer aufwendigen und belastenden vorbereitenden Therapie sowie der Gefahr der Entwicklung einer Graft-versus-Host-Erkrankung. Neuere Ansatze mit sog. ATMP („advanced therapy medicinal products“) setzen nur auf einen kurzzeitigen Chimarismus, der uber den Anstieg regulatorischer Zellpopulationen zu einer dauerhaften Transplantatakzeptanz fuhrt. Vielversprechend scheinen in diesem Zusammenhang Therapien mit regulatorischen T‑Zellen zu sein, diese konnen moglicherweise in Zukunft durch Einbringung eines chimaren Antigenrezeptors (CAR) weiter verbessert werden (sog. A2-CAR-Treg [„regulatory T cells“]). Einen anderen Ansatz stellt die Therapie mit MIC („modified immune cells“), ausgehend von Monozyten, dar. Diese Zellen fuhren beim Empfanger zu einer Reduktion der spenderspezifischen T‑Zell-Antwort und zur Ausbildung regulatorischer B‑Lymphozyten. Idealerweise sind regulatorische Zellprodukte zukunftig in der Lage, medikamentose Immunsuppression bei Transplantation und Autoimmunerkrankungen einzusparen oder vollstandig zu ersetzen. Regulatorische B‑Lymphozyten scheinen eine wichtige Rolle im Zusammenhang mit der Etablierung einer dauerhaften Transplantatakzeptanz zu spielen.

Background: to characterize humoral response after standard anti-SARS-CoV-2 vaccination in Rituximab-treated patients and to determine the optimal time point after last Rituximab treatment for appropriate immunization. Methods: sixty-four patients who received Rituximab within the last seven years prior to the first anti-SARS-CoV-2 vaccination were recruited in a prospective observational study. Anti-S1 IgG, SARS-CoV-2 specific neutralization, and various SARS-CoV-2 target antibodies were determined. A live virus assay was used to assess neutralizing antibody activity against B.1.617.2 (delta). In Rituximab-treated patients, CD19+ peripheral B-cells were quantified using flow cytometry. Results: after second vaccination, all antibodies were significantly reduced compared to healthy controls. Neutralizing antibody activity against B.1.617.2 (delta) was detectable with a median (IQR) ID50 of 0 (0–1:20) compared to 1:320 (1:160–1:320) in healthy controls (for all p < 0.001). Longer time period since last Rituximab administration correlated with higher anti-SARS-CoV-2 antibody levels and a stronger neutralization of B.1.617.2 (delta). With one exception, only patients with a CD19+ cell proportion ? 1% had detectable neutralizing antibodies. Conclusion: our data indicate that a reconstitution of the B-cell population to >1% seems crucial in developing neutralizing antibodies against SARS-CoV-2. We suggest that anti-SARS-CoV-2 vaccination should be administered at least 8–12 months after the last Rituximab treatment for sufficient humoral responses., Dietmar Hopp Stiftung; Heidelberg Faculty of Medicine Rahel Goitein-Strauss Program; Heidelberg Faculty of Medicine Physician Scientist Program; German Federal Research Network Applied Surveillance and Testing (BFAST); Network University Medicine; Virological and Immunological Determinants of COVID-19 Pathogenesis; Helmholtz Association Initiative and Networking Fund Project

To study the impact of glucocorticoid maintenance dose and treatment duration on outcomes in patients with AAV (ANCA-associated vasculitis) with emphasis on infectious complications. A total of 130 AAV patients from two German vasculitis centers diagnosed between August 2004 and January 2019 treated with cyclophosphamide and glucocorticoids for induction therapy and glucocorticoids for maintenance therapy were retrospectively enrolled. We investigated the influence of glucocorticoid maintenance therapy on patient survival, time to relapse, kidney function, infectious complications and irreversible physical damage. The patients were divided into the following groups: patients treated according to the predefined reduction scheme ($$\ge $$ ≥ 7.5 mg had an increased rate of infectious episodes per patient (1.7 vs. 0.6; p p = 0.007), pneumonia (p = 0.003), opportunistic pneumonia (p = 0.022) and sepsis (p = 0.008). Especially pneumonia during the first 24 months after disease onset [hazard ratio, 3.0 (95% CI 1.5 − 6.1)] led to more deaths from infection (p = 0.034). Glucocorticoid maintenance therapy after 6 months had no impact on relapse rate or patient survival and decline in kidney function was comparable. Glucocorticoid maintenance therapy with $$\ge $$ ≥ 7.5 mg after 6 months is associated with more severe infectious complications leading to an increased frequency of deaths from infection. Glucocorticoid maintenance therapy has no effect on time to relapse or patient survival and should therefore be critically revised throughout the aftercare of AAV patients.

Objectives: humoral immunity wanes over time after two-dose BNT162b2 vaccination. Emerging variants of concern, such as the B.1.617.2 (delta) variant, are increasingly responsible for breakthrough infections owing to their higher transmissibility and partial immune escape. Longitudinal data on neutralization against the B.1.617.2 (delta) variant are urgently needed to guide vaccination strategies. Methods: in this prospective longitudinal observational study, anti-S1 IgG and surrogate neutralizing antibodies were measured in 234 collected samples from 60 health care workers after two-dose vaccination with BNT162b2 at five different time points over an 8-month period. In addition, antibodies against various severe acute respiratory syndrome coronavirus 2 epitopes, neutralization against wild-type, and cross-neutralization against the B.1.617.2 (delta) variant using a live virus assay were measured 6 weeks (second time point) and 8 months (last time point) after first vaccine dose. Results: median (interquartile range) anti-S1 IgG, surrogate neutralizing, and receptor-binding domain antibodies decreased significantly from a maximum level of 147 (102–298), 97 (96–98), and 20 159 (19 023–21 628) to 8 (4–13), 92 (80–96), and 15 324 (13 055–17 288) at the 8-month follow-up, respectively (p < 0.001 for all). Neutralization against the B.1.617.2 (delta) variant was detectable in all 36 (100%) participants at 6 weeks and in 50 of 53 (94%) participants 8 months after first vaccine dose. Median (interquartile) ID50 as determined by a live virus assay decreased from 160 (80–320) to 40 (20–40) (p < 0.001). Discussion: although humoral immunity wanes over time after two-dose BNT162b2 vaccination in healthy individuals, most individuals still had detectable neutralizing activity against the B.1.617.2 (delta) variant after 8 months., Dietmar Hopp Stiftung; Heidelberg Faculty of Medicine Rahel Goitein-Strauss Program; Heidelberg Faculty of Medicine Physician Scientist Program; German Federal Research Network Applied Surveillance and Testing (BFAST); Network University Medicine; DKFZ@fightCOVID; Helmholtz Association Initiative and Networking Fund Project Virological and Immunological Determinants of COVID-19 Pathogenesis

Hemodialysis patients are at high risk for severe COVID-19, and impaired seroconversion rates have been demonstrated after COVID-19 vaccination. Humoral immunity wanes over time and variants of concern with immune escape are posing an increasing threat. Little is known about protection against the B.1.617.2 (delta) variant of concern in hemodialysis patients before and after third vaccination. We determined anti-S1 IgG, surrogate neutralizing, and IgG antibodies against different SARS-CoV-2 epitopes in 84 hemodialysis patients directly before and three weeks after a third vaccine dose with BNT162b2. Third vaccination was performed after a median (IQR) of 119 (109-165) days after second vaccination. In addition, neutralizing activity against the B.1.617.2 (delta) variant was assessed in 31 seroconverted hemodialysis patients before and after third vaccination. Triple seropositivity for anti-S1 IgG, surrogate neutralizing, and anti-RBD antibodies increased from 31/84 (37%) dialysis patients after second to 80/84 (95%) after third vaccination. Neutralizing activity against the B.1.617.2 (delta) variant was significantly higher after third vaccination with a median (IQR) ID50 of 1:320 (1:160-1:1280) compared with 1:20 (0-1:40) before a third vaccine dose (P, Dietmar Hopp Stiftung; Heidelberg Faculty of Medicine Rahel Goitein-Strauss Program

Chronic kidney failure (KF) provokes the development of immune senescent CD8

Because of the current organ shortage, ABO-incompatible (ABOi) transplantations have been increasingly performed in recent years. The results seem comparable to those of compatible transplantations, but there have also been reports of increased side effects possibly because of the desensitization therapy. To address an increase in severe infectious complications, we compared the outcomes of 48 ABOi transplant recipients to outcomes of 96 matched ABO-compatible (ABOc) controls transplanted at Heidelberg University Hospital from August 2005 to April 2018. Over a follow-up period of 8 years, ABOi transplant recipients had comparable graft and patient survival as well as graft function compared with ABOc patients. T-cell-mediated and antibody-mediated rejections were not different between groups. In ABOi transplant recipients, urosepsis (22.9% vs. 8.5%; P = 0.019) and pneumonia with opportunistic pathogens (8.3% vs. 1.0%, P = 0.025) appeared more frequently. As a consequence, a significantly higher number of deaths from infection have been observed after ABOi transplantations (6.3% vs. 0%, P = 0.010). High-titer recipients (isoagglutinin titer of ≥1:256) showed a higher incidence of BK virus replication and postoperative bleeding complications. ABO-incompatible transplantations can be performed with results that are not different from results after ABOc transplantations. However, an increased rate of serious infectious complications must be taken into account.

Dysregulations in the differentiation of CD4+-regulatory-T-cells (Tregs) and CD4+-responder-T-cells (Tresps) are involved in the development of active systemic lupus erythematosus (SLE). Three differentiation pathways of highly proliferative inducible costimulatory molecule (ICOS)+- and less proliferative ICOS−-CD45RA+CD31+-recent-thymic-emigrant (RTE)-Tregs/Tresps via CD45RA−CD31+-memory-Tregs/Tresps (CD31+-memory-Tregs/Tresps), their direct proliferation via CD45RA+CD31−-mature naïve (MN)-Tregs/Tresps, and the production and differentiation of resting MN-Tregs/Tresp into CD45RA−CD31−-memory-Tregs/Tresps (CD31−-memory-Tregs/Tresps) were examined in 115 healthy controls, 96 SLE remission patients, and 20 active disease patients using six color flow cytometric analysis. In healthy controls an appropriate sequence of these pathways ensured regular age-dependent differentiation. In SLE patients, an age-independently exaggerated differentiation was observed for all Treg/Tresp subsets, where the increased conversion of resting MN-Tregs/Tresps particularly guaranteed the significantly increased ratios of ICOS+-Tregs/ICOS+-Tresps and ICOS−-Tregs/ICOS−-Tresps during remission. Changes in the differentiation of resting ICOS+-MN-Tresps and ICOS−-MN-Tregs from conversion to proliferation caused a significant shift in the ratio of ICOS+-Tregs/ICOS+-Tresps in favor of ICOS+-Tresps and a further increase in the ratio of ICOS−-Tregs/ICOS−-Tresps with active disease. The differentiation of ICOS+-RTE-Tregs/Tresps seems to be crucial for keeping patients in remission, where their limited production of proliferating resting MN-Tregs may be responsible for the occurrence of active disease flares.

Treatment of ANCA-associated vasculitis (AAV) improved over the last decades but disease-unspecific agents such as cyclophosphamide are still associated with serious adverse events, including high rates of infectious complications and malignancy with increased mortality. In this comparative cohort study, we included 121 AAV patients with renal involvement from 2 German vasculitis centers. Patients were separated into subsequent groups: 2.5 to 3 g vs >3 g cumulative cyclophosphamide induction dose. We investigated if a cyclophosphamide induction dose of 2.5 to 3 g could maintain efficacy while minimizing adverse events in AAV patients with renal involvement. Patients with 2.5 to 3 g vs >3 g cumulative cyclophosphamide (median 3.0 g vs 5.5 g, P

Background and Aims An imbalance between CD4+-regulatory T-cells (Tregs) and CD4+-responder T-cells (Tresps) correlates with active disease flares in Systemic Lupus Erythematosus (SLE) patients. Both cell subsets consist of highly proliferative inducible T-cell co-stimulatory molecule expressing (ICOS+-) and less proliferating ICOS--Treg/Tresp cells. Method In this study we aimed to examine the role of age-dependent differentiation for maintaining the ICOS+-Treg/ICOS+-Tresp or ICOS--Treg/ICOS--Tresp balance in SLE remission patients compared to active disease patients and to evaluate the influence of proliferation inhibitor or glucocorticoid therapy concerning the maintenance of these equilibria. Results In 83 healthy volunteers, the ratio of ICOS+-Tregs/ICOS+-Tresps increased significantly with age, while that of ICOS--Tregs/ICOS--Tresps did not change. In 86 SLE remission patients, medication controlled disease activity was associated with an age-independently increased ratio of both ICOS+-Tregs/ICOS+-Tresps and ICOS--Tregs/ICOS--Tresps. In 13 active disease patients this increased ICOS+-Treg/ICOS+-Tresp ratio could not be maintained, due to an age-dependent earlier terminal differentiation of ICOS+-Tregs than of ICOS+-Tresps. The increased ratio of ICOS--Treg/ICOS--Tresp was maintained in active disease patients, but it decreased with age. This was attributable to an age-independent aberrant differentiation of ICOS--Tresps and a resulting loss of age-dependent differentiation of ICOS--Tregs. Especially the administration of proliferation inhibitors (azathioprine or mycophenolic acid) ensured prolonged differentiation and maintenance of functional ICOS+-Tregs with age. There was a similar but weaker effect of this medication on ICOS+-Tresps, causing a significant decrease of these cells with age. The proliferation capacity was neither affected in ICOS+-Tregs/Tresps nor in ICOS--Tregs/Tresps. As a result, the ratio of ICOS+-Tregs/ICOS+-Tresps increased significantly with age and kept the patients in remission. In contrast, glucocorticoids increased the differentiation of ICOS--Tregs especially in younger individuals, but had an adverse effect on their proliferation capacity. Conclusion Our data reveal a crucial role of the ICOS+-Treg/ICOS+-Tresp balance for the maintenance of self-tolerance and avoidance of disease flares in SLE. The used immunosuppressive therapy, especially the administration of proliferation inhibitors, has a decisive effect on the preservation of regular differentiation of all Treg/Tresp subsets with age, and most importantly avoids the terminal differentiation and immune senescence of ICOS+-Tregs.

BACKGROUND: Preclinical experiments have shown that donor blood cells, modified in vitro by an alkylating agent (modified immune cells [MICs]), induced long-term specific immunosuppression against the allogeneic donor. METHODS: In this phase I trial, patients received either 1.5 × 10(6) MICs per kg BW on day –2 (n = 3, group A), or 1.5 × 10(8) MICs per kg BW on day –2 (n = 3, group B) or day –7 (n = 4, group C) before living donor kidney transplantation in addition to post-transplantation immunosuppression. The primary outcome measure was the frequency of adverse events (AEs) until day 30 (study phase) with follow-up out to day 360. RESULTS: MIC infusions were extremely well tolerated. During the study phase, 10 treated patients experienced a total of 69 AEs that were unlikely to be related or not related to MIC infusion. No donor-specific human leukocyte antigen Abs or rejection episodes were noted, even though the patients received up to 1.3 × 10(10) donor mononuclear cells before transplantation. Group C patients with low immunosuppression during follow-up showed no in vitro reactivity against stimulatory donor blood cells on day 360, whereas reactivity against third-party cells was still preserved. Frequencies of CD19(+)CD24(hi)CD38(hi) transitional B lymphocytes (Bregs) increased from a median of 6% before MIC infusion to 20% on day 180, which was 19- and 68-fold higher, respectively, than in 2 independent cohorts of transplanted controls. The majority of Bregs produced the immunosuppressive cytokine IL-10. MIC-treated patients showed the Immune Tolerance Network operational tolerance signature. CONCLUSION: MIC administration was safe and could be a future tool for the targeted induction of tolerogenic Bregs. TRIAL REGISTRATION: EudraCT number: 2014-002086-30; ClinicalTrials.gov identifier: NCT02560220. FUNDING: Federal Ministry for Economic Affairs and Technology, Berlin, Germany, and TolerogenixX GmbH, Heidelberg, Germany.

Premature aging of both CD4+ regulatory T (Treg) and CD4+ responder‐T (Tresp) cells in patients with end‐stage renal disease (ESRD) is expected to affect the success of later kidney transplantation. Both T‐cell populations are released from the thymus as inducible T‐cell co‐stimulator‐positive (ICOS +) and ICOS − recent thymic emigrant (RTE) Treg/Tresp cells, which differ primarily in their proliferative capacities. In this study, we analysed the effect of ESRD and subsequent renal replacement therapies on the differentiation of ICOS + and ICOS − RTE Treg/Tresp cells into ICOS + CD31− or ICOS − CD31− memory Treg/Tresp cells and examined whether diverging pathways affected the suppressive activity of ICOS + and ICOS − Treg cells in co‐culture with autologous Tresp cells. Compared with healthy controls, we found an increased differentiation of ICOS + RTE Treg/Tresp cells and ICOS − RTE Treg cells through CD31+ memory Treg/Tresp cells into CD31− memory Treg/Tresp cells in ESRD and dialysis patients. In contrast, ICOS − RTE Tresp cells showed an increased differentiation via ICOS − mature naive (MN) Tresp cells into CD31− memory Tresp cells. Thereby, the ratio of ICOS + Treg/ICOS + Tresp cells was not changed, whereas that of ICOS − Treg/ICOS − Tresp cells was significantly increased. This differentiation preserved the suppressive activity of both Treg populations in ESRD and partly in dialysis patients. After transplantation, the increased differentiation of ICOS + and ICOS − RTE Tresp cells proceeded, whereas that of ICOS + RTE Treg cells ceased and that of ICOS − RTE Treg cells switched to an increased differentiation via ICOS − MN Treg cells. Consequently, the ratios of ICOS + Treg/ICOS + Tresp cells and of ICOS − Treg/ICOS − Tresp cells decreased significantly, reducing the suppressive activity of Treg cells markedly. Our data reveal that an increased tolerance‐inducing differentiation of ICOS + and ICOS − Treg cells preserves the functional activity of Treg cells in ESRD patients, but this cannot be maintained during long‐term renal replacement therapy.

A new immune monitoring tool which assesses the expression of nuclear factor of activated T cells (NFAT)-regulated genes measures the functional effects of cyclosporine A. This is the first prospective randomized controlled study to compare standard pharmacokinetic monitoring by cyclosporine trough levels to NFAT-regulated gene expression (NFAT-RE).Expression of the NFAT-regulated genes was determined by qRT-PCR at cyclosporine trough and peak level. Cardiovascular risk was assessed by change of pulse wave velocity from baseline to month 6. Clinical follow-up was 12 months.In total, 55 stable kidney allograft recipients were enrolled. Mean baseline residual NFAT-RE was 13.1 ± 9.1%. Patients in the NFAT-RE group showed a significant decline in pulse wave velocity from baseline to month 6 versus the standard group (-1.7 ± 2.0 m/s vs 0.4 ± 1.4 m/s, P0.001). Infections occurred more often in the standard group compared with the immune monitoring group. No opportunistic infections occurred with NFAT-RE monitoring. At 12 months of follow-up, renal function was significantly better with NFAT-RE versus standard monitoring (Nankivell glomerular filtration rate: 68.5 ± 17.4 mL/min vs 57.2 ± 19.0 mL/min; P = 0.009).NFAT-RE as translational immune monitoring tool proved efficacious and safe in individualizing cyclosporine therapy, with the opportunity to reduce the cardiovascular risk and improve long-term renal allograft function.

It has been demonstrated that patients on hemo- or peritoneal dialysis are particularly susceptible to SARS-CoV-2 infection and impaired seroconversion compared to healthy controls. Follow-up data on vaccination response in dialysis patients is limited but is greatly needed to individualize and guide (booster) vaccination strategies. In this prospective, multicenter study we measured anti-spike S1 and neutralizing antibodies in 124 hemodialysis patients, 41 peritoneal dialysis patients, and 20 age- and sex-matched healthy controls over 12 weeks after homologous BNT162b2 vaccination. Compared to healthy controls, both hemodialysis and peritoneal dialysis patients had lower anti-S1 IgG antibodies (median (IQR) 7.0 (2.8–24.3) and 21.8 (5.8–103.9) versus 134.9 (23.8–283.6), respectively, p &lt, 0.001 and p &lt, 0.05) and a reduced SARS-CoV-2 spike protein–ACE2 binding inhibition caused by vaccine-induced antibodies (median (IQR) 56% (40–81) and 77% (52–89) versus 96% (90–98), respectively, 0.01) three weeks after the second vaccination. Twelve weeks after the second vaccination, the spike protein–ACE2 binding inhibition significantly decreased to a median (IQR) of 45% (31–60) in hemodialysis patients and 55% (36–78) in peritoneal dialysis patients, respectively (p &lt, 0.05). Peritoneal dialysis patients mounted higher antibody levels compared with hemodialysis patients at all time points during the 12-week follow-up. Individual booster vaccinations in high-risk individuals without seroconversion or rapidly waning neutralizing antibody levels are required and further data on the neutralization of emerging variants of concern in these patients are urgently needed.

The introduction of calcineurin inhibitors (CNI) has greatly improved graft survival in the past three decades. However, long-term graft survival is still limited due to chronic allograft injury and side-effects of immunosuppressive medication. Areas covered: The present overview gives an update on pharmacotherapeutic strategies after kidney transplantation. The main focus is on CNI-sparing regimens using co-stimulatory blockade and on new substances on the horizone. Expert opinion: CNI sparing regimens are well-established. Complete CNI avoidance after kidney transplantation was often associated with impaired graft survival until the approval of the co-stimulation blocker belatacept for de novo immunosuppression after kidney transplantation. Concerns still exist with respect to severe T-cell-mediated rejection episodes in the early phase after transplantation. Thus, a triple drug regimen with CNI, mycophenolic acid and steroids still represents the gold-standard of immunosuppressive therapy. Alternative substances expand the possibilities of tailoring individual immunosuppression for different indications such as biopsy-proven CNI toxicity, polyoma virus BK nephropathy or CNI-triggered thrombotic microangiopathy. However, a change of the immunosuppressive therapy must always be balanced against each patient´s individual immunological risk in order to address the importance of chronic antibody-mediated rejection driven by donor specific antibodies (DSA).

Alternative C activation is involved in the pathogenesis of ANCA-associated vasculitis. However, glucocorticoids used as treatment contribute to the morbidity and mortality of vasculitis. We determined whether avacopan (CCX168), an orally administered, selective C5a receptor inhibitor, could replace oral glucocorticoids without compromising efficacy. In this randomized, placebo-controlled trial, adults with newly diagnosed or relapsing vasculitis received placebo plus prednisone starting at 60 mg daily (control group), avacopan (30 mg, twice daily) plus reduced-dose prednisone (20 mg daily), or avacopan (30 mg, twice daily) without prednisone. All patients received cyclophosphamide or rituximab. The primary efficacy measure was the proportion of patients achieving a ≥50% reduction in Birmingham Vasculitis Activity Score by week 12 and no worsening in any body system. We enrolled 67 patients, 23 in the control and 22 in each of the avacopan groups. Clinical response at week 12 was achieved in 14 of 20 (70.0%) control patients, 19 of 22 (86.4%) patients in the avacopan plus reduced-dose prednisone group (difference from control 16.4%; two-sided 90% confidence limit, −4.3% to 37.1%; P=0.002 for noninferiority), and 17 of 21 (81.0%) patients in the avacopan without prednisone group (difference from control 11.0%; two-sided 90% confidence limit, −11.0% to 32.9%; P=0.01 for noninferiority). Adverse events occurred in 21 of 23 (91%) control patients, 19 of 22 (86%) patients in the avacopan plus reduced-dose prednisone group, and 21 of 22 (96%) patients in the avacopan without prednisone group. In conclusion, C5a receptor inhibition with avacopan was effective in replacing high-dose glucocorticoids in treating vasculitis.

Refinement of immunosuppressive strategies has led to further improvement of kidney graft survival in recent years. Currently, the main limitations to long-term graft survival are life-threatening side effects of immunosuppression and chronic allograft injury, emphasizing the need for innovative immunosuppressive regimens that resolve this therapeutic dilemma. Several cell therapeutic approaches to immunosuppression and donor-specific unresponsiveness have been tested in early phase I and phase II clinical trials in kidney transplantation. The aim of this overview is to summarize current cell therapeutic approaches to immunosuppression in clinical kidney transplantation with a focus on myeloid suppressor cell therapy by mitomycin C-induced cells (MICs). MICs show great promise as a therapeutic agent to achieve the rapid and durable establishment of donor-unresponsiveness in living-donor kidney transplantation. Cell-based therapeutic approaches may eventually revolutionize immunosuppression in kidney transplantation in the near future.

In recent studies, semi-selective compared to antigen-specific immunoadsorption (IA) columns showed comparable effectiveness in anti-A/B antibody removal before incompatible living donor kidney transplantation. Semi-selective columns allow a greater number of IA treatments at lower costs. They are also capable of removing potentially harmful human leukocyte antigen alloantibodies. Nevertheless, additional plasma exchange treatments are often necessary to reach the preoperative target titer, most likely due to an inadequate anti-A/B IgM antibody depletion.We compared the effectiveness of immunoglobulin and anti-A/B antibody reduction by different semi-selective (Therasorb Ig-flex, Therasorb Ig-omni5, Immunosorba) and antigen-specific (Glycosorb) IA columns during the desensitization of 63 ABO-incompatible living donor kidney transplant candidates with a total of 375 IA treatments. Fifty-three patients were eventually transplanted.Total IgM reduction during the first IA treatment was significantly greater with the Therasorb Ig-omni5 compared to the Therasorb Ig-flex (mean: -71.3 vs -41.6; p = 0.001) or Immunosorba columns (mean: -71.3 vs -42.8; p = 0.03). During a median of 5.5-6 pre-transplant IA treatments, Therasorb Ig-flex and Therasorb Ig-omni5 columns were equally effective in the reduction of total IgM while both showed superior IgM reduction compared to the Immunosorba columns (Therasorb Ig-flex, mean: -81.2 vs -72.2; p = 0.01; Therasorb Ig-omni5, mean: -88.2 vs -72.2; p = 0.02). IgG reduction was not significantly different between groups. Likewise, anti-A/B IgM antibody reduction (titer Saline) during the first IA treatment was significantly greater with the Therasorb Ig-omni5 compared to the Therasorb Ig-flex (mean titer reduction: -1.9 vs -1.1; p = 0.02) and tended to be greater than with Immunosorba or Glycosorb columns. During a median of 5-6 pre-transplant IA treatments, overall anti-A/B IgM antibody reduction was significantly greater when IA was performed with the Therasorb Ig-flex (mean titer reduction: -3.8 vs -1.3; p 0.001) or Therasorb Ig-omni5 (mean titer reduction: -4.3 vs -1.3; p = 0.01) compared to the Immunosorba columns with no differences compared to the Glycosorb columns. Again, anti-A/B IgG antibody reduction (titer Coombs) was not significantly different between groups.The semi-selective Therasorb Ig-omni5 device offers potential advantages in reducing total IgM as well as anti-A/B IgM antibodies.

Background: Modified immune cells (MICs) are mononuclear cells that gain immunosuppressive properties after incubation with the proliferation inhibitor mitomycin C. We recently showed that syngeneic MIC therapy controlled experimental autoimmune encephalitis (EAE) (1). In addition, allogeneic MIC therapy prevented rejection in rat heart and hindlimb as well as pig kidney transplantation (2). Objectives: We now wanted to translate these encouraging findings to the prevention and treatment of lupus nephritis. Methods: Splenocytes of syngeneic NZB/W F1 (BWF1) donor mice were incubated with mitomycin C and injected into recipient’s tail vein after matching for age and disease activity. Group 1 received no MIC therapy, group 2 standard-dose MIC therapy with 1.5x108/kg BW once and group 3 repeated MIC therapy with 1.5x108/kg BW at weeks 1, 2 and 3. Group 4 received MIC infusions before disease onset as preemptive treatment approach. Disease activity was monitored by loss of body weight, protein excretion, serum creatinine and dsDNA antibodies. Combined primary endpoint was day 40 post-treatment, protein excretion ≥3g/l for 2 consecutive weeks and >30% loss of original body weight. Histopathology with PAS and HE staining was performed to assess degree of lupus nephritis. Regulatory cell subsets were measured in peripheral blood. Results: MIC therapy prevented the progression of fatal lupus nephritis in BWF1 mice. Protein excretion, serum creatinine and dsDNA antibodies were lower in standard-dose (group 2) and preemptive (group 4) groups compared to control group (group 1) whereas repeated MIC therapy after disease onset had no effect (Figure 1A-E). The primary endpoint was reached significantly more often in control group (group 1, 67%) compared to treatment groups 2 (14%), 3 (14%) and 4 (0%) (Figure 1F). Renal architecture was preserved in different MIC treatment groups (groups 2-4) with decreased glomerular and tubular damage scores (Figure 1G). Most importantly, frequencies of CD8+CD25+FoxP3+ regulatory T cells and CD19+CD5+CD1dhigh regulatory B cells were significantly higher in MIC-treated (groups 2-4) compared to control animals of group 1, whereas double negative T cells were markedly reduced (Figure 1H). Conclusion: MIC therapy inhibits progression of active lupus nephritis. Interestingly, preemptive MIC therapy was even able to prevent onset of disease with no significant disease activity at completion of the study. In accordance with our previous pre-clinical EAE experiments (1) and a first in-human clinical trial in living-donor kidney transplantation (TOL-1 study), MIC therapy was able to induce an in-vivo induction of regulatory cell subsets. This clinically applicable cell therapeutic approach may control lupus nephritis by specifically silencing deleterious autoimmune responses. References: [1] Terness P, Oelert T, et al. Mitomycin C-treated dendritic cells inactivate autoreactive T cells: toward the development of a tolerogenic vaccine in autoimmune diseases. Proc Natl Acad Sci USA. 2008 Nov 25;105(47):18442–7. [2] Jiga LP, Ehser S, Kleist C, Opelz G, Terness P. Inhibition of heart allograft rejection with mitomycin C-treated donor dendritic cells. Transplantation. 2007 Feb 15;83(3):347–50. Disclosure of Interests: Claudius Speer Grant/research support from: Research Grant from TolerogenixX GmbH, Daniela Kim Grant/research support from: Research Grant from TolerogenixX GmbH, Christian Kleist Shareholder of: TolerogenixX GmbH, Anita Schmitt Shareholder of: TolerogenixX GmbH, Michael Schmitt: None declared, Claudia Sommerer: None declared, Andrea Steinborn: None declared, Florian Kalble: None declared, Christian Nusshag: None declared, Lei Wang Grant/research support from: Research Grant from TolerogenixX GmbH, Employee of: TolerogenixX GmbH, Alexander Kunz Grant/research support from: Research Grant from TolerogenixX GmbH, Employee of: TolerogenixX GmbH, Hanns-Martin Lorenz: None declared, Martin Zeier: None declared, Christian Morath Shareholder of: TolerogenixX GmbH, Matthias Schaier Shareholder of: TolerogenixX GmbH

Background Modified immune cells (MICs) are mononuclear cells that gain immunosuppressive properties after incubation with the proliferation inhibitor mitomycin C. We showed that syngeneic MIC cell therapy prevented experimental autoimmune encephalitis (EAE) as well as alloreactive rejection in rat heart and hindlimb and pig kidney transplantation. We now aimed to translate these encouraging investigations to prevent murine lupus nephritis and control autoimmunity by MIC therapy. Methods Splenocytes of syngeneic NZB/W F1 (BWF1) mice were harvested from a donor, incubated with mitomycin C and injected into recipients tail vein after matching for age and disease activity. Group 1 received no MIC therapy, group 2 standard-dose MIC therapy with 1.5 × 108/kg BW once and group 3 repeated MIC therapy with 1.5 × 108/kg BW at week 1, 2 and 3, respectively. Group 4 was dosed with repeated MIC therapy before disease onset as preemptive treatment approach. Disease activity was monitored by loss of body weight, protein excretion and serum creatinine. Combined primary endpoint was day 40 post-treatment, protein excretion 3 g/L for 2 consecutive weeks and >30% loss of original body weight. Histopathology with PAS and HE staining was performed to assess degree of lupus nephritis. In the peripheral blood we determined regulatory cell subsets. Results MIC therapy prevented the progression of fatal lupus nephritis in BMF1 mice. Protein excretion and serum creatinine were lower in standard-dose group and preemptive group compared to control group whereas repeated MIC therapy in active disease failed to inhibit both significantly. Accomplishment of combined primary endpoint was significantly increased in group 1 (67%) compared to group 2 (14%), group 3 (14%) and group 4 (0%), respectively. Renal architecture was preserved throughout different MIC treatment groups with decreased glomerular and tubular damage scores. After MIC therapy, frequencies of CD8 +CD25+FoxP3+regulatory T cells and CD19 +CD5+CD1 dhigh regulatory B cells increased significantly, whereas double negative T cells were markedly reduced throughout all treatment groups. Conclusions MIC therapy inhibits progression of active lupus nephritis. Interestingly, preemptive MIC therapy was even able to prevent onset of disease since no significant disease activity was observed at completion of the study. In accordance with our previous pre-clinical EAE experiments and a first in-human clinical trial in living-donor kidney transplantation (TOL-1 study), MIC therapy enables an in-vivo induction of regulatory cell subsets. This clinically applicable cell therapeutic approach may control lupus nephritis by specifically silencing deleterious autoimmune response. Funding Source(s): Research grant from TolerogenixX GmbH Disease activity was assessed after MIC cell therapy by loss of original body weight (A), protein excretion via semiquantitative sticks (B), albuminuria via ELISA (C) and serum creatinine via ELISA (D). Primary endpoint was defined as day 40 post-treatment, protein excretion 3 g/L for 2 consecutive weeks and >30% loss of original body weight (E). Histopathology with PAS and HE staining was performed. Representative PAS staining for different treatment groups and the control group are shown (F). Different regulatory cell subsets as well as DN T cells were determined in peripheral blood. Representative dot plots of regulatory CD19 +CD5+CD1 dhigh B cells, CD8 +CD25+FoxP3+T cells and CD3 +CD4 CD8- double-negative T cells are shown (G).

Problem Recent studies revealed appropriate differentiation of recent thymic emigrant (RTE)-regulatory T cells (Tregs) to be crucial for maintaining healthy pregnancy. Currently, the role of responder T cells (Tresps) is not known. Method of study Six-color flow cytometric analysis was used to detect differences in the differentiation of highly proliferative inducible co-stimulatory (ICOS)+-RTE-Tregs/Tresps and apoptosis-sensitive ICOS−-RTE-Tregs/Tresps into mature naive (MN)-, CD31+-memory and CD31−-memory Tregs/Tresps in women with spontaneous preterm labor (sPL) compared to healthy pregnancy. Results Healthy pregnancy was characterized by an increased differentiation of ICOS+- and ICOS−-RTE-Tregs, as well as ICOS+-RTE-Tresps via CD31+-memory Tregs/Tresps into CD31−-memory Tregs/Tresps. Women with sPL showed an early interruption of RTE-Treg/Tresp differentiation. Instead, ICOS+-MN-Tresps and partly ICOS−-MN-Tregs differentiated into CD31−-memory Tregs/Tresps, causing a significant reduction of both ICOS+-Tregs and ICOS+-Tresps, but an increase of ICOS−-Tresps within total CD4+-T-helper cells. Conclusion Aberrant differentiation of ICOS+-T cells is associated with sPL.

Background CD4+ T cells are of great importance in the pathogenesis of systemic lupus erythematosus (SLE), as an imbalance between CD4+ regulatory T cells (Tregs) and CD4+ responder T cells (Tresps) causes flares of active disease in SLE patients. In this study, we aimed to find the role of aberrant Treg/Tresp cell differentiation for maintaining Treg/Tresp cell balance and Treg functionality. Methods To determine differences in the differentiation of Tregs/Tresps we calculated the percentages of CD45RA+CD31+ recent thymic emigrant (RTE) Tregs/Tresps and CD45RA+CD31− mature naive (MN) Tregs/Tresps, as well as CD45RA−CD31+ and CD45RA−CD31− memory Tregs/Tresps (CD31+ and CD31− memory Tregs/Tresps) within the total Treg/Tresp pool of 78 SLE remission patients compared with 94 healthy controls of different ages. The proliferation capacity of each Treg/Tresp subset was determined by staining the cells with anti-Ki67 monoclonal antibodies. Differences in the autologous or allogeneic Treg function between SLE remission patients and healthy controls were determined using suppression assays. Results With age, we found an increased differentiation of RTE Tregs via CD31+ memory Tregs and of RTE Tresps via MN Tresps into CD31− memory Tregs/Tresp in healthy volunteers. This opposite differentiation of RTE Tregs and Tresps was associated with an age-dependent increase in the suppressive activity of both naive and memory Tregs. SLE patients showed similar age-dependent Treg cell differentiation. However, in these patients RTE Tresps differentiated increasingly via CD31+ memory Tresps, whereby CD31− memory Tresps arose that were much more difficult to inhibit for Tregs than those that emerged through differentiation via MN Tresps. Consequently, the increase in the suppressive activity of Tregs with age could not be maintained in SLE patients. Testing the Tregs of healthy volunteers and SLE patients with autologous and nonautologous Tresps revealed that the significantly decreased Treg function in SLE patients was not exclusively attributed to an age-dependent diminished sensitivity of the Tresps for Treg suppression. The immunosuppressive therapy reduced the accelerated age-dependent Tresp cell proliferation to normal levels, but simultaneously inhibited Treg cell proliferation below normal levels. Conclusions Our data reveal that the currently used immunosuppressive therapy has a favorable effect on the differentiation and proliferation of Tresps but has a rather unfavorable effect on the proliferation of Tregs. Newer substances with more specific effects on the immune system would be desirable. Electronic supplementary material The online version of this article (10.1186/s13075-018-1778-6) contains supplementary material, which is available to authorized users.