ObjectiveTo assess whether reshaping of the immune balance by infusion of autologous natural regulatory T cells (nTregs) in patients after kidney transplantation is safe, feasible, and enables the tapering of lifelong high dose immunosuppression, with its limited efficacy, adverse effects, and high direct and indirect costs, along with addressing several key challenges of nTreg treatment, such as easy and robust manufacturing, danger of over immunosuppression, interaction with standard care drugs, and functional stability in an inflammatory environment in a useful proof-of-concept disease model.DesignInvestigator initiated, monocentre, nTreg dose escalation, phase I/IIa clinical trial (ONEnTreg13).SettingCharité-University Hospital, Berlin, Germany, within the ONE study consortium (funded by the European Union).ParticipantsRecipients of living donor kidney transplant (ONEnTreg13, n=11) and corresponding reference group trial (ONErgt11-CHA, n=9).InterventionsCD4+ CD25+ FoxP3+ nTreg products were given seven days after kidney transplantation as one intravenous dose of 0.5, 1.0, or 2.5-3.0×106 cells/kg body weight, with subsequent stepwise tapering of triple immunosuppression to low dose tacrolimus monotherapy until week 48.Main outcome measuresThe primary clinical and safety endpoints were assessed by a composite endpoint at week 60 with further three year follow-up. The assessment included incidence of biopsy confirmed acute rejection, assessment of nTreg infusion related adverse effects, and signs of over immunosuppression. Secondary endpoints addressed allograft functions. Accompanying research included a comprehensive exploratory biomarker portfolio.ResultsFor all patients, nTreg products with sufficient yield, purity, and functionality could be generated from 40-50 mL of peripheral blood taken two weeks before kidney transplantation. None of the three nTreg dose escalation groups had dose limiting toxicity. The nTreg and reference groups had 100% three year allograft survival and similar clinical and safety profiles. Stable monotherapy immunosuppression was achieved in eight of 11 (73%) patients receiving nTregs, while the reference group remained on standard dual or triple drug immunosuppression (P=0.002). Mechanistically, the activation of conventional T cells was reduced and nTregs shifted in vivo from a polyclonal to an oligoclonal T cell receptor repertoire.ConclusionsThe application of autologous nTregs was safe and feasible even in patients who had a kidney transplant and were immunosuppressed. These results warrant further evaluation of Treg efficacy and serve as the basis for the development of next generation nTreg approaches in transplantation and any immunopathologies.Trial registrationNCT02371434 (ONEnTreg13) and EudraCT:2011-004301-24 (ONErgt11).

Cytomegalovirus (CMV) infections have a major impact on morbidity and mortality of transplant patients. Among the complex antiviral T-cell response, CMV-IE-1 antigen-specific CD8+ cells are crucial for preventing CMV disease but do not protect from recurring/lasting CMV reactivation. Recently, we confirmed that adoptive transfer of autologous IE-1/pp65-specific T-cell lines was able to combat severe CMV disease; however, the control of CMV infection was only temporary. We hypothesized that CMV-induced regulatory T cells (iTreg) might be related to recurring/lasting CMV infection.

EBV infection leads to life-long viral persistence. Although EBV infection can result in chronic disease and malignant transformation, most carriers remain disease-free as a result of effective control by T cells. EBV-specific IFN-c-producing T cells could be demonstrated in acute and chronic infection as well as during latency. Recent studies, however, provide evidence that assessing IFN-c alone is insufficient to assess the quantity and quality of a T-cell response. Using overlapping peptide pools of latent EBV nuclear antigen 1 and lytic BZLF-1 protein and multicolor flow cytometry, we demonstrate that the majority of ex vivo EBV-reactive T cells in healthy virus carriers are indeed IL-2-and/or TNF-producing memory cells, the latter being significantly more frequent in BM. After in vitro expansion, a substantial number of EBV-specific CD4 1 and CD8 1 T cells retained a CC-chemokine receptor 7 (CCR7)-positive memory phenotype. Based on their cytokine profiles, six different EBV-specific T-cell subsets could be distinguished with TNF-single or TNF/IL-2-double producing cells expressing the highest CCR7 levels resembling earlydifferentiated memory T cells. Our study delineates the memory T-cell profile of a protective immune response and provides a basis for analyzing T-cell responses in EBVassociated diseases.Key words: BM . EBV . Immune monitoring . Multifunctional T cells . T-cell memory IntroductionEBV is a human gamma herpesvirus that is widespread in all human populations. Following oral transmission, EBV replicates in the oropharyngeal epithelial cells and infects mucosal B cells, leading to a life-long persistence in the memory B-cell pool [1,2]. The primary infection occurs usually during childhood and is often asymptomatic; however, infection is manifested as acute infectious mononucleosis in a subset of patients [3]. Despite the relatively benign course in most carriers, EBV reactivation is considered as a risk-factor both for malignant transformation and autoimmune diseases. The ability of the EBV encoded protein 1566LMP-1 to induce T-cell-independent immunoglobulin class switch DNA recombination and BAFF, a B-cell activating factor, that rescues self-reactive T cells, is considered to play an important role in the pathogenesis of EBV-related autoimmune and lymphoproliferative disease [4]. EBV is causatively linked to nasopharyngeal carcinoma and B-cell malignant diseases such as endemic Burkitt's lymphoma, Hodgkin's lymphoma and posttransplant lymphoproliferative diseases (PTLD) [5][6][7]. Recent data suggest that EBV is associated with various autoimmune diseases as systemic lupus erythematosus, rheumatoid arthritis, multiple sclerosis and primary Sjögren's syndrome [8,9]. Chronic active EBV infection can also cause Chronic Fatigue Syndrome, which is frequently associated with autoimmune thyreoiditis [10].The EBV cycle has two distinct stages, the latent infection where the genome is maintained at a constant copy number per cell and limited regions of the genome are expressed and the lytic cycle w...

Chronically immunosuppressed patients, like solid-organ-transplant (SOT) recipients, are at increased risk for severe human cytomegalovirus (HCMV) infection. Despite the availability of effective antiviral drugs, lasting control of remaining viruses is dependent on an effective T-cell immunity. So in some patients conventional antiviral therapy cannot control the infection and prolonged virostatic therapy is limited by its side effects and the development of viral resistance. Selective reconstitution of cellular immunity by adoptive transfer of HCMV-specific T cells derived from healthy donors is a safe and effective approach in hematopoietic stem cell transplant recipients. The aim of this study was to determine whether functional HCMV-specific T cells can also be generated from chronically immunosuppressed patients. Autologous CD4+/8+ T-cell lines directed against the HCMV protein IE-1 were generated from the peripheral blood of SOT patients using a recently developed modular protocol easily applicable to good-manufacturing-practice conditions. T-cell lines from SOT patients showed similar features as cells from healthy donors regarding phenotype, functionality (HCMV-specific killing, gene expression pattern, and cytokine secretion), IE-1 epitope recognition, and dominance of distinct T-cell receptor V beta families. Most importantly, this protocol also allowed the generation of T-cell lines from immunosuppressed patients with HCMV infection/chronic HCMV disease. Our data suggest the potential of this autologous approach for the treatment of SOT recipients suffering from HCMV infection/disease poorly responding to virostatic therapy.

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Adoptive transfer of regulatory T cells (Treg) is a promising new therapeutic option to treat detrimental inflammatory conditions after transplantation and during autoimmune disease. To reach sufficient cell yield for treatment, ex vivo isolated autologous or allogenic Tregs need to be expanded extensively in vitro during manufacturing of the Treg product. However, repetitive cycles of restimulation and prolonged culture have been shown to impact T cell phenotypes, functionality and fitness. It is therefore critical to scrutinize the molecular changes which occur during T cell product generation, and reexamine current manufacturing practices. We performed genome-wide DNA methylation profiling of cells throughout the manufacturing process of a polyclonal Treg product that has proven safety and hints of therapeutic efficacy in kidney transplant patients. We found progressive DNA methylation changes over the duration of culture, which were donor-independent and reproducible between manufacturing runs. Differentially methylated regions (DMRs) in the final products were significantly enriched at promoters and enhancers of genes implicated in T cell activation. Additionally, significant hypomethylation did also occur in promoters of genes implicated in functional exhaustion in conventional T cells, some of which, however, have been reported to strengthen immunosuppressive effector function in Tregs. At the same time, a set of reported Treg-specific demethylated regions increased methylation levels with culture, indicating a possible destabilization of Treg identity during manufacturing, which was independent of the purity of the starting material. Together, our results indicate that the repetitive TCR-mediated stimulation lead to epigenetic changes that might impact functionality of Treg products in multiple ways, by possibly shifting to an effector Treg phenotype with enhanced functional activity or by risking destabilization of Treg identity and impaired TCR activation. Our analyses also illustrate the value of epigenetic profiling for the evaluation of T cell product manufacturing pipelines, which might open new avenues for the improvement of current adoptive Treg therapies with relevance for conventional effector T cell products.

Cell therapies have significant therapeutic potential in diverse fields including regenerative medicine, transplantation tolerance, and autoimmunity. Within these fields, regulatory T cells (Treg) have been deployed to ameliorate aberrant immune responses with great success. However, translation of the cryopreservation strategies employed for other cell therapy products, such as effector T cell therapies, to Treg therapies has been challenging. The lack of an optimized cryopreservation strategy for Treg products presents a substantial obstacle to their broader application, particularly as administration of fresh cells limits the window available for sterility and functional assessment. In this study, we aimed to develop an optimized cryopreservation strategy for our CD4+CD25+Foxp3+ Treg clinical product. We investigate the effect of synthetic or organic cryoprotectants including different concentrations of DMSO on Treg recovery, viability, phenotype, cytokine production, suppressive capacity, and in vivo survival following GMP-compliant manufacture. We additionally assess the effect of adding the extracellular cryoprotectant polyethylene glycol (PEG), or priming cellular expression of heat shock proteins as strategies to improve viability. We find that cryopreservation in serum-free freezing medium supplemented with 10% human serum albumin and 5% DMSO facilitates improved Treg recovery and functionality and supports a reduced DMSO concentration in Treg cryopreservation protocols. This strategy may be easily incorporated into clinical manufacture protocols for future studies.