Generation and characterization of antagonistic anti-human CD39 nanobodies

CD39 is the major enzyme controlling the levels of extracellular adenosine triphosphate (ATP) via the stepwise hydrolysis of ATP to adenosine diphosphate (ADP) and adenosine monophosphate (AMP). As extracellular ATP is a strong promoter of inflammation, monoclonal antibodies (mAbs) blocking CD39 are utilized therapeutically in the field of immune-oncology. Though anti-CD39 mAbs are highly specific for their target, they lack deep penetration into the dense tissue of solid tumors, due to their large size. To overcome this limitation, we generated and characterized nanobodies that targeted and blocked human CD39. From cDNA-immunized alpacas we selected 16 clones from seven nanobody families that bind to two distinct epitopes of human CD39. Among these, clone SB24 inhibited the enzymatic activity of CD39. Of note, SB24 blocked ATP degradation by both soluble and cell surface CD39 as a 15kD monomeric nanobody. Dimerization via fusion to an immunoglobulin Fc portion further increased the blocking potency of SB24 on CD39-transfected HEK cells. Finally, we confirmed the CD39 blocking properties of SB24 on human PBMCs. In summary, SB24 provides a new small biological antagonist of human CD39 with potential application in cancer therapy.

Thymic Atrophy and Immune Dysregulation in Infants with Complex Congenital Heart Disease

Congenital heart disease (CHD) is the most common birth defect, and up to 50% of infants with CHD require cardiovascular surgery early in life. Current clinical practice often involves thymus resection during cardiac surgery, detrimentally affecting T-cell immunity. However, epidemiological data indicate that CHD patients face an elevated risk for infections and immune-mediated diseases, independent of thymectomy. Hence, we examined whether the cardiac defect impacts thymus function in individuals with CHD. We investigated thymocyte development in 58 infants categorized by CHD complexity. To assess the relationship between CHD complexity and thymic function, we analyzed T-cell development, thymic output, and biomarkers linked to cardiac defects, stress, or inflammation. Patients with highly complex CHD exhibit thymic atrophy, resulting in low frequencies of recent thymic emigrants in peripheral blood, even prior to thymectomy. Elevated plasma cortisol levels were detected in all CHD patients, while high NT-proBNP and IL-6 levels were associated with thymic atrophy. Our findings reveal an association between complex CHD and thymic atrophy, resulting in reduced thymic output. Consequently, thymus preservation during cardiovascular surgery could significantly enhance immune function and the long-term health of CHD patients.

Purinergic enzymes on extracellular vesicles: immune modulation on the go

An increase in the extracellular concentration of ATP as a consequence of cellular stress or cell death results in the activation of immune cells. To prevent inflammation, extracellular ATP is rapidly metabolized to adenosine, which deploys an anti-inflammatory signaling cascade upon binding to P1 receptors on immune cells. The ectonucleotidases necessary for the degradation of ATP and generation of adenosine are present on the cell membrane of many immune cells, and their expression is tightly regulated under conditions of inflammation. The discovery that extracellular vesicles (EVs) carry purinergic enzyme activity has brought forward the concept of EVs as a new player in immune regulation. Adenosine-generating EVs derived from cancer cells suppress the anti-tumor response, while EVs derived from immune or mesenchymal stem cells contribute to the restoration of homeostasis after infection. Here we will review the existing knowledge on EVs containing purinergic enzymes and molecules, and discuss the relevance of these EVs in immune modulation and their potential for therapy.

Reduction of IFN-I responses by plasmacytoid dendritic cells in a longitudinal trans men cohort

Type I interferons (IFN-I) are important mediators of antiviral immunity and autoimmune diseases. Female plasmacytoid dendritic cells (pDCs) exert an elevated capacity to produce IFN-I upon toll-like receptor 7 (TLR7) activation compared to male pDCs, and both sex hormones and X-encoded genes have been implicated in these sex-specific differences. Using longitudinal samples from a trans men cohort receiving gender-affirming hormone therapy (GAHT), the impact of testosterone injections on TLR7-mediated IFN-I production by pDCs was assessed. Single-cell RNA analyses of pDCs showed downregulation of IFN-I-related gene expression signatures but also revealed transcriptional inter-donor heterogeneity. Longitudinal quantification showed continuous reduction of IFN-I protein production by pDCs and reduced expression of IFN-I-stimulated genes in peripheral blood mononuclear cells (PBMCs). These studies in trans men demonstrate that testosterone administration reduces IFN-I production by pDCs over time and provide insights into the immune-modulatory role of testosterone in sex-specific IFN-I-mediated immune responses.

The Clinical Significance of CD73 in Cancer

The search for new and effective treatment targets for cancer immunotherapy is an ongoing challenge. Alongside the more established inhibitory immune checkpoints, a novel potential target is CD73. As one of the key enzymes in the purinergic signalling pathway CD73 is responsible for the generation of immune suppressive adenosine. The expression of CD73 is higher in tumours than in the corresponding healthy tissues and associated with a poor prognosis. CD73, mainly by the production of adenosine, is critical in the suppression of an adequate anti-tumour immune response, but also in promoting cancer cell proliferation, tumour growth, angiogenesis, and metastasis. The upregulation of CD73 and generation of adenosine by tumour or tumour-associated immune cells is a common resistance mechanism to many cancer treatments such as chemotherapy, radiotherapy, targeted therapy, and immunotherapy. Therefore, the inhibition of CD73 represents a new and promising approach to increase therapy efficacy. Several CD73 inhibitors have already been developed and successfully demonstrated anti-cancer activity in preclinical studies. Currently, clinical studies evaluate CD73 inhibitors in different therapy combinations and tumour entities. The initial results suggest that inhibiting CD73 could be an effective option to augment anti-cancer immunotherapeutic strategies. This review provides an overview of the rationale behind the CD73 inhibition in different treatment combinations and the role of CD73 as a prognostic marker.

The role of the ATP-adenosine axis in ischemic stroke

In ischemic stroke, the primary neuronal injury caused by the disruption of energy supply is further exacerbated by secondary sterile inflammation. The inflammatory cascade is largely initiated by the purine adenosine triphosphate (ATP) which is extensively released to the interstitial space during brain ischemia and functions as an extracellular danger signaling molecule. By engaging P2 receptors, extracellular ATP activates microglia leading to cytokine and chemokine production and subsequent immune cell recruitment from the periphery which further amplifies post-stroke inflammation. The ectonucleotidases CD39 and CD73 shape and balance the inflammatory environment by stepwise degrading extracellular ATP to adenosine which itself has neuroprotective and anti-inflammatory signaling properties. The neuroprotective effects of adenosine are mainly mediated through A₁ receptors and inhibition of glutamatergic excitotoxicity, while the anti-inflammatory capacities of adenosine have been primarily attributed to A_2A receptor activation on infiltrating immune cells in the subacute phase after stroke. In this review, we summarize the current state of knowledge on the ATP-adenosine axis in ischemic stroke, discuss contradictory results, and point out potential pitfalls towards translating therapeutic approaches from rodent stroke models to human patients.

Ex Vivo Model of Neuroblastoma Plasticity

Tumor plasticity is essential for adaptation to changing environmental conditions, in particular during the process of metastasis. In this study, we compared morphological and biochemical differences between LAN-1 neuroblastoma (NB) cells recovered from a subcutaneous xenograft primary tumor (PT) and the corresponding three generations of bone metastasis (BM I-III). Moreover, growth behavior, as well as the response to chemotherapy and immune cells were assessed. For this purpose, F-actin was stained, mRNA and protein expression assessed, and lactate secretion analyzed. Further, we measured adhesion to collagen I, the growth rate of spheroids in the presence and absence of vincristine, and the production of IL-6 by peripheral blood mononuclear cells (PBMCs) co-incubated with PT or BM I-III. Analysis of PT and the three BM generations revealed that their growth rate decreased from PT to BM III, and accordingly, PT cells reacted most sensitively to vincristine. In addition, morphology, adaption to hypoxic conditions, as well as transcriptomes showed strong differences between the cell lines. Moreover, BM I and BM II cells exhibited a significantly different ability to stimulate human immune cells compared to PT and BM III cells. Interestingly, the differences in immune cell stimulation corresponded to the expression level of the cancer-testis antigen MAGE-A3. In conclusion, our ex vivo model allows to analyze the adaption of tumor populations to different microenvironments and clearly demonstrates the strong alteration of tumor cell populations during this process.

Impact of Betamethasone Pretreatment on Engrafment of Cord Blood-Derived Hematopoietic Stem Cells

Hematopoietic stem cell (HSC) transplantation is crucial to cure hematologic malignancies. Umbilical cord blood (UCB) is a source of stem cells, but 90% of UCB units are discarded due to low cellularity. Improving the engraftment capacities of CD34⁺ stem cells would allow the use of UCB that were so far rejected. Betamethasone induces long-term transcriptomic and epigenomic changes in immune cells through glucocorticoid receptor. We hypothesize that discarded UCB could be used owing to improvements induced by betamethasone. Isolated CD34⁺ HSC from UCB were exposed to the synthetic glucocorticoids betamethasone and fluticasone for 20 h, and cell phenotype was determined before transplantation. NSG mice were sub-lethally irradiated (1 Gy or 2 Gy) 6 h before intravenously transferring 2-5 × 10⁵ CD34⁺ HSC. The peripheral blood engraftment levels and the leukocyte subsets were followed up for 20 weeks using flow cytometry. At end point, the engraftment and leukocyte subsets were determined in the spleen and bone marrow. We demonstrated that betamethasone has surprising effects in recovering immune system homeostasis. Betamethasone and fluticasone increase CXCR4 and decrease HLA class II and CD54 expression in CD34⁺ HSCs. Both glucocorticoids-exposed cells showed a similar engraftment in 2 Gy-irradiated NSG mice. Interestingly, betamethasone-exposed cells showed enhanced engraftment in 1 Gy-irradiated NSG mice, with a trend to increase regulatory T cell percentage when compared to control. Betamethasone induces alterations in CD34⁺ HSCs and improve the engraftment, leading to a faster immune system recovery, which will contribute to engrafted cells survival.

IMMU-20. MODULATION OF THE PERIPHERAL T CELL BIOLOGY IN GLIOBLASTOMA

Cancer is a systemic disease. Due to the exceedingly rare occurrence of metastasis of cerebral glioma, systemic alterations have, however, not been considered to play a major role in disease progression of glioma. T cells orchestrate the adaptive immune response in an antigen-specific, cytokine mediated manner. The aim of our study was to investigate how cerebral glioma impacts systemic T cell immunobiology. We performed gene expression profiling of peripheral blood T cells in patients with IDHwt glioblastomas as well as in a murine glioma model. In addition, we analyzed the levels of soluble immune biomarkers in patient blood and performed flow-cytometric phenotyping of human peripheral blood CD3+ T cells. We discovered a significant skewing of peripheral T cell phenotypes in IDHwt glioblastoma patients compared to healthy donors (HD), showing CD4+ TH1 expansion and reduced numbers of T follicular helper cells (TFH), TH1* and mucosa associated invariant T (MAIT) cells, while TH2 and TH17 percentages remained stable. Interestingly, peripheral memory CD4+ T cells exhibited reduced Fas and PD-1 expression, while CD8 T cells were primarily affected in the non-memory CD45RA+ compartment, displaying reduced numbers of CD8+ CD127+ CD27+ cells. Compared to healthy individuals, GBM patients had significantly increased levels of soluble CD27 while levels of soluble CD25 were reduced (p < 0.05). GSEA and ORA analysis of differentially expressed genes in murine gliomas showed alterations in RNA binding and processing, as well as ribosomal activity in both cell types, indicating systemic modulation in translational- and cell cycle pathways in glioblastoma. Taken together, our results demonstrate a significant skewing of the peripheral T immunobiology in patients with IDHwt gliomas. Our data highlights the importance of considering malignant glioma as a systemic disease that fundamentally alters the immune repertoire in affected patients.

P2×7 is expressed on human innate-like T lymphocytes and mediates susceptibility to ATP-induced cell death

Extracellular ATP activates the P2×7 receptor, leading to inflammasome activation and release of pro-inflammatory cytokines in monocytes. However, a detailed analysis of P2×7 receptor expression and function in the human T cell compartment has not been reported. Here, we used a P2×7-specific nanobody to assess cell membrane expression and function of P2×7 on peripheral T lymphocyte subsets. The results show that innate-like T cells, which effectively react to innate stimuli by secreting high amounts of pro-inflammatory cytokines, have the highest expression of P2×7 in the human T cell compartment. Using Tγδ cells as example for an innate-like lymphocyte population, we demonstrate that these cells are more sensitive to P2×7 receptor activation than conventional T cells, affecting fundamental cellular mechanisms like calcium signaling and ATP-induced cell death. The increased susceptibility of innate-like T cells to P2×7-mediated cell death provides a mechanism to control their homeostasis under inflammatory conditions. Understanding the expression and function of P2×7 on human immune cells is essential to assume the benefits and consequences of newly developed P2×7-based therapeutic approaches. This article is protected by copyright. All rights reserved.

Protein kinase inhibitor ceritinib blocks ectonucleotidase CD39 - a promising target for cancer immunotherapy

Background

An important mechanism, by which cancer cells achieve immune escape, is the release of extracellular adenosine into their microenvironment. Adenosine activates adenosine A_2A and A_2B receptors on immune cells constituting one of the strongest immunosuppressive mediators. In addition, extracellular adenosine promotes angiogenesis, tumor cell proliferation, and metastasis. Cancer cells upregulate ectonucleotidases, most importantly CD39 and CD73, which catalyze the hydrolysis of extracellular ATP to AMP (CD39) and further to adenosine (CD73). Inhibition of CD39 is thus expected to be an effective strategy for the (immuno)therapy of cancer. However, suitable small molecule inhibitors for CD39 are not available. Our aim was to identify drug-like CD39 inhibitors and evaluate them in vitro.

Methods

We pursued a repurposing approach by screening a self-compiled collection of approved, mostly ATP-competitive protein kinase inhibitors, on human CD39. The best hit compound was further characterized and evaluated in various orthogonal assays and enzyme preparations, and on human immune and cancer cells.

Results

The tyrosine kinase inhibitor ceritinib, a potent anticancer drug used for the treatment of anaplastic lymphoma kinase (ALK)-positive metastatic non-small cell lung cancer, was found to strongly inhibit CD39 showing selectivity versus other ectonucleotidases. The drug displays a non-competitive, allosteric mechanism of CD39 inhibition exhibiting potency in the low micromolar range, which is independent of substrate (ATP) concentration. We could show that ceritinib inhibits ATP dephosphorylation in peripheral blood mononuclear cells in a dose-dependent manner, resulting in a significant increase in ATP concentrations and preventing adenosine formation from ATP. Importantly, ceritinib (1–10 µM) substantially inhibited ATP hydrolysis in triple negative breast cancer and melanoma cells with high native expression of CD39.

Conclusions

CD39 inhibition might contribute to the effects of the powerful anticancer drug ceritinib. Ceritinib is a novel CD39 inhibitor with high metabolic stability and optimized physicochemical properties; according to our knowledge, it is the first brain-permeant CD39 inhibitor. Our discovery will provide the basis (i) to develop more potent and balanced dual CD39/ALK inhibitors, and (ii) to optimize the ceritinib scaffold towards interaction with CD39 to obtain potent and selective drug-like CD39 inhibitors for future in vivo studies.

Specific CD4+ T Cell Responses to Ancestral SARS-CoV-2 in Children Increase With Age and Show Cross-Reactivity to Beta Variant

SARS-CoV-2 is still a major burden for global health despite effective vaccines. With the reduction of social distancing measures, infection rates are increasing in children, while data on the pediatric immune response to SARS-CoV-2 infection is still lacking. Although the typical disease course in children has been mild, emerging variants may present new challenges in this age group. Peripheral blood mononuclear cells (PBMC) from 51 convalescent children, 24 seronegative siblings from early 2020, and 51 unexposed controls were stimulated with SARS-CoV-2-derived peptide MegaPools from the ancestral and beta variants. Flow cytometric determination of activation-induced markers and secreted cytokines were used to quantify the CD4+ T cell response. The average time after infection was over 80 days. CD4+ T cell responses were detected in 61% of convalescent children and were markedly reduced in preschool children. Cross-reactive T cells for the SARS-CoV-2 beta variant were identified in 45% of cases after infection with an ancestral SARS-CoV-2 variant. The CD4+ T cell response was accompanied most predominantly by IFN-γ and Granzyme B secretion. An antiviral CD4+ T cell response was present in children after ancestral SARS-CoV-2 infection, which was reduced in the youngest age group. We detected significant cross-reactivity of CD4+ T cell responses to the more recently evolved immune-escaping beta variant. Our findings have epidemiologic relevance for children regarding novel viral variants of concern and vaccination efforts.

Alterations of NK Cell Phenotype During Pregnancy in Multiple Sclerosis

In multiple sclerosis (MS), relapse rate is decreased by 70-80% in the third trimester of pregnancy. However, the underlying mechanisms driving this effect are poorly understood. Evidence suggests that CD56^bright NK cell frequencies increase during pregnancy. Here, we analyze pregnancy-related NK cell shifts in a large longitudinal cohort of pregnant women with and without MS, and provide in-depth phenotyping of NK cells. In healthy pregnancy and pregnancy in MS, peripheral blood NK cells showed significant frequency shifts, notably an increase of CD56^bright NK cells and a decrease of CD56^dim NK cells toward the third trimester, indicating a general rather than an MS-specific phenomenon of pregnancy. Additional follow-ups in women with MS showed a reversal of NK cell changes postpartum. Moreover, high-dimensional profiling revealed a specific CD56^bright subset with receptor expression related to cytotoxicity and cell activity (e.g., CD16⁺ NKp46^high NKG2D^high NKG2A^high phenotype) that may drive the expansion of CD56^bright NK cells during pregnancy in MS. Our data confirm that pregnancy promotes pronounced shifts of NK cells toward the regulatory CD56^bright population. Although exploratory results on in-depth CD56^bright phenotype need to be confirmed in larger studies, our findings suggest an increased regulatory NK activity, thereby potentially contributing to disease amelioration of MS during pregnancy.

Nt5e deficiency does not affect post-stroke inflammation and lesion size in a murine ischemia/reperfusion stroke model

Extracellular ATP released to the ischemic brain parenchyma is quickly metabolized by ectonucleotidases. Among them, the ecto-5′-nucleotidase CD73 encoded by Nt5e generates immunosuppressive adenosine. Genetic deletion of Nt5e led to increased infarct size in the murine photothrombotic stroke model. We aimed at validating this result using the transient middle cerebral artery occlusion (tMCAO) stroke model that represents pathophysiological aspects of penumbra and reperfusion. Three days after tMACO, we did not detect a difference in stroke size between CD73-deficient (CD73^−/−) and control mice. Consistent with this finding, CD73^−/− and control mice showed comparable numbers and composition of brain-infiltrating leukocytes measured by flow cytometry. Using NanoString technology, we further demonstrated that CD73^−/− and control mice do not differ regarding glia cell gene expression profiles. Our findings highlight the potential impact of stroke models on study outcome and the need for cross-validation of originally promising immunomodulatory candidates.

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Infarct volume on day 3 after tMCAO was comparable among CD73^−/− and control mice

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Brain leukocyte infiltration on day 3 after tMCAO was similar in CD73^−/− and control mice

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Glial RNA expression profile on day 3 after tMCAO was similar in CD73^−/− and control mice

Immune signature of multiple sclerosis-associated depression

Multiple neurobiological pathways have been implicated in the pathobiology of major depressive disorder (MDD). The identification of reliable biological substrates across the entire MDD spectrum, however, is hampered by a vast heterogeneity in the clinical presentation, presumably as a consequence of heterogeneous pathobiology. One way to overcome this limitation could be to explore disease subtypes based on biological similarity such as "inflammatory depression". As such a subtype may be particularly enriched in depressed patients with an underlying inflammatory condition, multiple sclerosis (MS) could provide an informative disease context for this approach. Few studies have explored immune markers of MS-associated depression and replications are missing. To address this, we analyzed data from two independent case-control studies on immune signatures of MS-associated depression, conducted at two different academic MS centers (overall sample size of n = 132). Using a stepwise data-driven approach, we identified CD4⁺CCR7^lowT_CM cell frequencies as a robust correlate of depression in MS. This signature was associated with core symptoms of depression and depression severity (but not MS severity per se) and linked to neuroinflammation as determined by magnetic resonance imaging (MRI). Furthermore, exploratory analyses of T cell polarization revealed this was largely driven by cells with a T_H1-like phenotype. Our findings suggest (neuro)immune pathways linked to affective symptoms of autoimmune disorders such as MS, with potential relevance for the understanding of "inflammatory" subtypes of depression.

Treating sarcoidosis-associated progressive multifocal leukoencephalopathy with infliximab

Although most of the progressive multifocal leukoencephalopathy cases in sarcoidosis patients are explained by the treatment with immunosuppressive drugs, it is also reported in treatment-naive sarcoidosis patients, which implies a general predisposition of sarcoidosis patients for progressive multifocal leukoencephalopathy. Indeed, it was shown that active sarcoidosis patients have increased regulatory T cell frequencies which could lead to a subsequent systemic immunosuppression. However, if sarcoidosis with systemic changes of T cell subsets frequencies constitute a risk factor for the development of progressive multifocal leukoencephalopathy, which could then be counteracted by sarcoidosis treatment, is not known. In this cohort study, we included, characterized and followed-up six patients with bioptically confirmed definite progressive multifocal leukoencephalopathy and definite or probable sarcoidosis presenting between April 2013 and January 2019, four of them had no immunosuppressive therapy at the time of developing first progressive multifocal leukoencephalopathy symptoms. Analysis of immune cell subsets in these patients revealed significant imbalances of CD4⁺ T cell and regulatory T cell frequencies. Due to the progression of progressive multifocal leukoencephalopathy in four patients, we decided to treat sarcoidosis anticipating normalization of immune cell subset frequencies and thereby improving progressive multifocal leukoencephalopathy. Notably, by treatment with infliximab, an antibody directed against tumour necrosis factor-α, three patients continuously improved clinically, JC virus was no longer detectable in the cerebrospinal fluid and regulatory T cell frequencies decreased. One patient was initially misdiagnosed as neurosarcoidosis and died 9 weeks after treatment initiation due to aspiration pneumonia. Our study provides insight that sarcoidosis can lead to changes in T cell subset frequencies, which predisposes to progressive multifocal leukoencephalopathy. Although immunosuppressive drugs should be avoided in progressive multifocal leukoencephalopathy, paradoxically in patients with sarcoidosis treatment with the immunosuppressive infliximab might restore normal T cell distribution and thereby halt progressive multifocal leukoencephalopathy progression.

Phenotypic analysis of the pediatric immune response to SARS-CoV-2 by flow cytometry

INTRODUCTION

Pediatric SARS-CoV-2 infection is often mild or asymptomatic and the immune responses of children are understudied compared to adults. Here, we present and evaluate the performance of a two-panel (16- and 17 parameter) flow cytometry-based approach for immune phenotypic analysis of cryopreserved PBMC samples from children after SARS-CoV-2 infection. The panels were optimized based on previous SARS-CoV-2 related studies for the pediatric immune system.

METHODS

PBMC samples from seven SARS-CoV-2 seropositive children from early 2020 and five age-matched healthy controls were stained for analysis of T cells (Panel T), B and innate immune cells (Panel B). Performance of the panels was evaluated in two parallel approaches, namely classical manual gating of known subpopulations and unbiased clustering using the R-based algorithm PhenoGraph.

RESULTS

Using manual gating we clearly identified 14 predefined subpopulations of interest for Panel T and 19 populations in Panel B in low-volume pediatric samples. PhenoGraph found 18 clusters within the T cell panel and 21 clusters within the innate and B cell panel that could be unmistakably annotated. Combining the data of the two panels and analysis approaches, we found expected differentially abundant clusters in SARS-CoV-2 seropositive children compared to healthy controls, underscoring the value of these two panels for the analysis of immune response to SARS-CoV-2.

CONCLUSION

We established a two-panel flow cytometry approach that can be used with limited amounts of cryopreserved pediatric samples. Our workflow allowed for a rapid, comprehensive, and robust pediatric immune phenotyping with comparable performance in manual gating and unbiased clustering. These panels may be adapted for large multi-center cohort studies to investigate the pediatric immune response to emerging virus variants in the ongoing and future pandemics. This article is protected by copyright. All rights reserved.

The New Old CD8+ T Cells in the Immune Paradox of Pregnancy

CD8+ T cells are the most frequent T cell population in the immune cell compartment at the feto-maternal interface. Due to their cytotoxic potential, the presence of CD8+ T cells in the immune privileged pregnant uterus has raised considerable interest. Here, we review our current understanding of CD8+ T cell biology in the uterus of pregnant women and discuss this knowledge in relation to a recently published immune cell Atlas of human decidua. We describe how the expansion of CD8+ T cells with an effector memory phenotype often presenting markers of exhaustion is critical for a successful pregnancy, and host defense towards pathogens. Moreover, we review new evidence on the presence of long-lasting immunological memory to former pregnancies and discuss its impact on prospective pregnancy outcomes. The formation of fetal-specific memory CD8+ T cell subests in the uterus, in particular of tissue resident, and stem cell memory cells requires further investigation, but promises interesting results to come. Advancing the knowledge of CD8+ T cell biology in the pregnant uterus will be pivotal for understanding not only tissue-specific immune tolerance but also the etiology of complications during pregnancy, thus enabling preventive or therapeutic interventions in the future.

CD73-mediated adenosine production by CD8 T cell-derived extracellular vesicles constitutes an intrinsic mechanism of immune suppression

Immune cells at sites of inflammation are continuously activated by local antigens and cytokines, and regulatory mechanisms must be enacted to control inflammation. The stepwise hydrolysis of extracellular ATP by ectonucleotidases CD39 and CD73 generates adenosine, a potent immune suppressor. Here we report that human effector CD8 T cells contribute to adenosine production by releasing CD73-containing extracellular vesicles upon activation. These extracellular vesicles have AMPase activity, and the resulting adenosine mediates immune suppression independently of regulatory T cells. In addition, we show that extracellular vesicles isolated from the synovial fluid of patients with juvenile idiopathic arthritis contribute to T cell suppression in a CD73-dependent manner. Our results suggest that the generation of adenosine upon T cell activation is an intrinsic mechanism of human effector T cells that complements regulatory T cell-mediated suppression in the inflamed tissue. Finally, our data underscore the role of immune cell-derived extracellular vesicles in the control of immune responses.

Identification of the Mouse T Cell ADP-Ribosylome Uncovers ARTC2.2 Mediated Regulation of CD73 by ADP-Ribosylation

Mouse T cells express the ecto-ADP-ribosyltransferase ARTC2.2, which can transfer the ADP-ribose group of extracellular nicotinamide adenine dinucleotide (NAD⁺) to arginine residues of various cell surface proteins thereby influencing their function. Several targets of ARTC2.2, such as P2X7, CD8a and CD25 have been identified, however a comprehensive mouse T cell surface ADP-ribosylome analysis is currently missing. Using the Af1521 macrodomain-based enrichment of ADP-ribosylated peptides and mass spectrometry, we identified 93 ADP-ribsoylated peptides corresponding to 67 distinct T cell proteins, including known targets such as CD8a and CD25 but also previously unknown targets such as CD73. We evaluated the impact of ADP-ribosylation on the capability of CD73 to generate adenosine from adenosine monophosphate. Our results show that extracellular NAD⁺ reduces the enzymatic activity of CD73 HEK cells co-transfected with CD73/ARTC2.2. Importantly, NAD⁺ significantly reduced CD73 activity on WT CD8 T cells compared to ARTC2ko CD8 T cells or WT CD8 T cells treated with an ARTC2.2-blocking nanobody. Our study provides a comprehensive list of T cell membrane proteins that serve as targets for ADP-ribosylation by ARTC2.2 and whose function may be therefore affected by ADP-ribosylation.

P16.03 Cerebral gliom alters the peripheral CD4+ T helper cell phenotype

BACKGROUND

Cancer is a systemic disease. Due to the exceedingly rare occurrence of metastasis of cerebral glioma, systemic alterations have, however, not been considered to play a major role in disease progression of glioma. CD4+ T helper (TH) cells orchestrate the adaptive immune response in an antigen-specific, cytokine mediated manner. The aim of our study was to investigate how far cerebral glioma impacts the systemic CD4+ immune repertoire.

MATERIAL AND METHODS

We performed flow-cytometry analysis of the peripheral blood CD4+ TH cell phenotype and cytokine production in 100 patients with IDHwt, 30 IDHmut and 16 IDHmut 1p19q co-deleted gliomas in comparison with age-matched healthy donors (HD). Data was analyzed using a Fortessa LSR and Diva software. Multiparameter analyses were performed using UMAP and SpadeVizR trees. The study was approved by the ethics committee (PV4904).

RESULTS

We found a significant skewing of the peripheral immunophenotype in IDHwt glioma patients, showing a TH1 expansion and reduced numbers of T follicular helper cells (TFH), TH1* and mucosa associated invariant T (MAIT) cells (p<0.001), while TH2 and TH17 percentages remained stable compared to IDHmut and HD. Although TH1 cells were dominant in IDHwt patients (p<0.01), intracellular cytokine staining showed a reduction of IFNγ and TNFα production after in vitro stimulation, while IL-4 was significantly increased compared to HD (p<0.05). No alterations between all groups were observed in IL-2, IL-10 or IL-17 production. Profiling of metabolic surface markers further revealed increased expression of GLUT1 on CD4+ T cells in IDHwt patients, indicating an activated CD4+ repertoire compared to HD.

CONCLUSION

Taken together, our results show a CD4+ TH cell type specific skewing of the peripheral immune repertoire in patients with IDHwt gliomas. Our data highlights the importance of considering malignant glioma as a disease with profound systemic effects fundamentally altering the immune repertoire in affected patients.

Single-cell atlas of hepatic T cells reveals expansion of liver-resident naive-like CD4+ T cells in primary sclerosing cholangitis

BACKGROUND & AIMS

Little is known about the composition of intrahepatic immune cells and their contribution to the pathogenesis of primary sclerosing cholangitis (PSC). Herein, we aimed to create an atlas of intrahepatic T cells and thereby perform an in-depth characterization of T cells in inflamed human liver.

METHODS

Different single-cell RNA sequencing methods were combined with in silico analyses on intrahepatic and peripheral T cells from patients with PSC (n = 11) and healthy donors (HDs, n = 4). Multi-parameter flow cytometry and functional in vitro experiments were conducted on samples from patients with PSC (n = 24), controls with other liver diseases and HDs.

RESULTS

We identified a population of intrahepatic naive-like CD4⁺ T cells, which was present in all liver diseases tested, but particularly expanded in PSC. This population had a transcriptome and T cell receptor repertoire similar to circulating naive T cells but expressed a set of genes associated with tissue residency. Their periductal location supported the concept of tissue-resident naive-like T cells in livers of patients with PSC. Trajectory inference suggested that these cells had the developmental propensity to acquire a T helper 17 (T_H17) polarization state. Functional and chromatin accessibility experiments revealed that circulating naive T cells in patients with PSC were predisposed to polarize towards T_H17 cells.

CONCLUSION

We report the first atlas of intrahepatic T cells in PSC, which led to the identification of a previously unrecognized population of tissue-resident naive-like T cells in the inflamed human liver and to the finding that naive CD4⁺ T cells in PSC harbour the propensity to develop into T_H17 cells.

LAY SUMMARY

The composition of intrahepatic immune cells in primary sclerosing cholangitis (PSC) and their contribution to disease pathogenesis is widely unknown. We analysed intrahepatic T cells and identified a previously uncharacterized population of liver-resident CD4⁺ T cells which are expanded in the livers of patients with PSC compared to healthy liver tissue and other liver diseases. These cells are likely to contribute to the pathogenesis of PSC and could be targeted in novel therapeutic approaches.

Increased frequency of TIGIT+CD73-CD8+ T cells with a TOX+ TCF-1low profile in patients with newly diagnosed and relapsed AML

The inhibitory receptor TIGIT, as well as theectonucleotidases CD39 and CD73 constitute potential exhaustion markers for T cells. Detailed analysis of these markers can shed light into dysregulation of the T-cell response in acute myeloid leukemia (AML) and will help to identify potential therapeutic targets.  The phenotype and expression of transcription factors was assessed on different T-cell populations derived from peripheral blood (PB, n = 38) and bone marrow (BM, n = 43). PB and BM from patients with AML diagnosis, in remission and at relapse were compared with PB from healthy volunteers (HD) (n = 12) using multiparameter flow cytometry. An increased frequency of terminally differentiated (CD45R^-CCR7^-)CD8⁺ T cells was detected in PB and BM regardless of the disease state. Moreover, we detected an increased frequency of two distinct T-cell populations characterized by the co-expression of PD-1 or CD39 on TIGIT⁺CD73^-CD8⁺ T cells in newly diagnosed and relapsed AML in comparison to HDs. In contrast to the PD-1⁺TIGIT⁺CD73^-CD8⁺ T-cell population, the frequency of CD39⁺TIGIT⁺CD73^-CD8⁺ T cells was normalized in remission. PD-1⁺- and CD39⁺TIGIT⁺CD73^-CD8⁺ T cells exhibited additional features of exhaustion by decreased expression of CD127 and TCF-1 and increased intracellular expression of the transcription factor TOX. CD8⁺ T cells in AML exhibit a key signature of two subpopulations, PD-1⁺TOX⁺TIGIT⁺CD73^-CD8⁺- and CD39⁺TOX⁺TIGIT⁺CD73^-CD8⁺ T cells that were increased at different stages of the disease. These results provide a rationale to analyze TIGIT blockade in combination with inhibition of the purinergic signaling and depletion of TOX to improve T-cell mediated cytotoxicity in AML. Abbreviations: AML: Acute myeloid leukemia; pAML: newly diagnosed AML; rAML: relapse AML; lrAML: AML in remission; HD: healthy donor; PB: peripheral blood; BM: bone marrow; TIGIT: T-cell immunoreceptor with Ig and ITIM domains; PD-1: Programmed cell death protein 1; CD73: ecto-5'-nucleotidase; CD39: ectonucleoside triphosphate diphosphohydrolase 1; ATP: adenosine triphosphate; ADO: adenosine; CD127: interleukin-7 receptor; CAR-T cell: chimeric antigen receptor T cell; TCF-1: transcription factor T-cell factor 1; TOX: Thymocyte selection-associated high mobility group box protein; NFAT: nuclear factor of activated T cells; NA: Naïve; CM: Central Memory; EM Effector Memory; EMRA: Terminal Effector Memory cells; FMO: Fluorescence minus one; PVR: poliovirus receptor; PVRL2: poliovirus receptor-related 2; IFN-γ: Interferon-γ; IL-2: interleukin-2; MCF: multiparametric flow cytometry; TNFα: Tumornekrosefaktor α; RT: room temperature.

A simple, sensitive, and low-cost FACS assay for detecting antibodies against the native SARS-CoV-2 spike protein

Background: Hamburg is a city state of approximately 1.9 Mio inhabitants in Northern Germany. Currently, the COVID‐19 epidemic that had largely subsided during last summer is resurging in Hamburg and in other parts of the world, underlining the need for additional tools to monitor SARS‐CoV‐2 antibody responses.

Aim: We aimed to develop and validate a simple, low‐cost assay for detecting antibodies against the native coronavirus 2 spike protein (CoV‐2 S) that does not require recombinant protein or virus.

Method: We transiently co‐transfected HEK cells or CHO cells with expression vectors encoding CoV‐2 S and nuclear GFP. Spike protein‐specific antibodies in human serum samples bound to transfected cells were detected with fluorochrome conjugated secondary antibodies by flow cytometry orimmunofluorescence microscopy. We applied this assay to monitor antibody development in COVID‐19 patients, household contacts, and hospital personnel during the ongoing epidemic in the city state of Hamburg.

Results: All recovered COVID‐19 patients showed high levels of CoV‐2 S‐specific antibodies. With one exception, all household members that did not develop symptoms also did not develop detectable antibodies. Similarly, lab personnel that worked during the epidemic and followed social distancing guidelines remained antibody‐negative.

Conclusion: We conclude that high‐titer CoV‐2 S‐specific antibodies are found in most recovered COVID‐19 patients and in symptomatic contacts, but only rarely in asymptomatic contacts. The assay may help health care providers to monitor disease progression and antibody responses in vaccination trials, to identify health care personnel that likely are resistant to re‐infection, and recovered individuals with high antibody titers that may be suitable asplasma and/or antibody donors.

Vesical Imaging-Reporting and Data System (VI-RADS®): Initial experience in the classification of muscle-invasive bladder cancer

OBJECTIVE

to analyze the diagnostic accuracy of the VI-RADS® system in the differentiation of non-muscle-invasive bladder tumors (NMIBT from muscle-invasive bladder tumors (MIBT in suspicious cystoscopic findings without prior transurethral resection (TUR evaluated by radiologists with no prior experience in its use.

MATERIAL AND METHODS

retrospective study carried out with 18 patients with suspicious lesions in cystoscopy. All of them underwent MRI of the bladder. Two radiologists with no prior experience in the use of the VI-RADS® system evaluated the results. All patients underwent TUR of the suspicious lesions after MRI. The sensitivity and specificity of the system were analyzed for VI-RADS® values ≥ 3 or VI-RADS® ≥ 4, as well as the Cohen's kappa coefficient between both radiologists.

RESULTS

the mean values of sensitivity and specificity of both radiologists considering both the VI-RADS® ≥ 3 or VI-RADS® ≥ 4 values were 91.7% and 87.5%, respectively. The kappa coefficient considering the VI-RADS® ≥ 3 as positive, was 0.551 (P<.05), while considering the VI-RADS® ≥ 4 as positive, it was 0.571 (P<.05).

CONCLUSION

The VI--RADS® system presents excellent sensitivity (91.7% and specificity (87.5% values in the classification of MIBT performed by radiologists with no prior experience in its use, with a moderate interobserver agreement.

The transcription factor Bcl11b promotes both canonical and adaptive NK cell differentiation

Epigenetic landscapes can provide insight into regulation of gene expression and cellular diversity. Here, we examined the transcriptional and epigenetic profiles of seven human blood natural killer (NK) cell populations, including adaptive NK cells. The BCL11B gene, encoding a transcription factor (TF) essential for T cell development and function, was the most extensively regulated, with expression increasing throughout NK cell differentiation. Several Bcl11b-regulated genes associated with T cell signaling were specifically expressed in adaptive NK cell subsets. Regulatory networks revealed reciprocal regulation at distinct stages of NK cell differentiation, with Bcl11b repressing RUNX2 and ZBTB16 in canonical and adaptive NK cells, respectively. A critical role for Bcl11b in driving NK cell differentiation was corroborated in BCL11B-mutated patients and by ectopic Bcl11b expression. Moreover, Bcl11b was required for adaptive NK cell responses in a murine cytomegalovirus model, supporting expansion of these cells. Together, we define the TF regulatory circuitry of human NK cells and uncover a critical role for Bcl11b in promoting NK cell differentiation and function.

OMIP 073: Analysis of human thymocyte development with a 14-color flow cytometry panel

This panel was designed for the identification and detailed characterization of the different developmental steps of human thymocytes. We optimized the panel for fresh tissue in order to provide an unbiased analysis of T cell development. Accurate selection of antibodies and precise gating allow us to phenotype 14 major stages of human thymocyte development and illustrate the trajectories of T cell development from early thymic progenitors (ETP) to mature T cells that are ready to populate the periphery. The panel identifies ETPs, T-lineage-committed cells (TC), CD34-positive immature single-positive CD4 cells (ISP4 CD34+), CD34-negative immature single-positive CD4 cells (ISP4 CD34-), CD45-low early double-positive cells (EDP CD45low), CD45-high early double-positive cells (EDP CD45high), late double-positive cells (LDP), single-positive CD4 cells (SP4), single-positive CD8 cells (SP8), ready-to-egress single-positive CD4 cells (rSP4), ready-to-egress single-positive CD8 cells (rSP8), T γδ cells (Tγδ), T regulatory cells (Treg), and ready-to-egress T regulatory cells (rTreg). To highlight important checkpoints during T cell development, we added antibodies relevant for specific developmental steps to the panel. These include CD1a to define TCs, CD28 as a marker for ß-selection and CD69 in combination with CD45RA to determine the maturation stage of thymocytes shortly before they become ready to egress the thymus and colonize the periphery. Moreover, Annexin V, as a marker for apoptosis, provides valuable extra information concerning the apoptotic death of thymocytes. Currently, we use this panel to identify aberrations in T cell development in health and disease.

2-Methoxyestradiol and its derivatives inhibit store-operated Ca2+ entry in T cells: Identification of a new and potent inhibitor

T cell activation starts with formation of second messengers that release Ca²⁺ from the endoplasmic reticulum (ER) and thereby activate store-operated Ca²⁺ entry (SOCE), one of the essential signals for T cell activation. Recently, the steroidal 2-methoxyestradiol was shown to inhibit nuclear translocation of the nuclear factor of activated T cells (NFAT). We therefore investigated 2-methoxyestradiol for inhibition of Ca²⁺ entry in T cells, screened a library of 2-methoxyestradiol analogues, and characterized the derivative 2-ethyl-3-sulfamoyloxy-17β-cyanomethylestra-1,3,5(10)-triene (STX564) as a novel, potent and specific SOCE inhibitor. STX564 inhibits Ca²⁺ entry via SOCE without affecting other ion channels and pumps involved in Ca²⁺ signaling in T cells. Downstream effects such as cytokine expression and cell proliferation were also inhibited by both 2-methoxyestradiol and STX564, which has potential as a new chemical biology tool.

T Cell Repertoire Dynamics during Pregnancy in Multiple Sclerosis

Identifying T cell clones associated with human autoimmunity has remained challenging. Intriguingly, many autoimmune diseases, including multiple sclerosis (MS), show strongly diminished activity during pregnancy, providing a unique research paradigm to explore dynamics of immune repertoire changes during active and inactive disease. Here, we characterize immunomodulation at the single-clone level by sequencing the T cell repertoire in healthy women and female MS patients over the course of pregnancy. Clonality is significantly reduced from the first to third trimester in MS patients, indicating that the T cell repertoire becomes less dominated by expanded clones. However, only a few T cell clones are substantially modulated during pregnancy in each patient. Moreover, relapse-associated T cell clones identified in an individual patient contract during pregnancy and expand during a postpartum relapse. Our data provide evidence that profiling the T cell repertoire during pregnancy could serve as a tool to discover and track "private" T cell clones associated with disease activity in autoimmunity.

Next-Generation Sequencing of T and B Cell Receptor Repertoires from COVID-19 Patients Showed Signatures Associated with Severity of Disease

We profiled adaptive immunity in COVID-19 patients with active infection or after recovery and created a repository of currently >14 million B and T cell receptor (BCR and TCR) sequences from the blood of these patients. The B cell response showed converging IGHV3-driven BCR clusters closely associated with SARS-CoV-2 antibodies. Clonality and skewing of TCR repertoires were associated with interferon type I and III responses, early CD4+ and CD8+ T cell activation, and counterregulation by the co-receptors BTLA, Tim-3, PD-1, TIGIT, and CD73. Tfh, Th17-like, and nonconventional (but not classical antiviral) Th1 cell polarizations were induced. SARS-CoV-2-specific T cell responses were driven by TCR clusters shared between patients with a characteristic trajectory of clonotypes and traceability over the disease course. Our data provide fundamental insight into adaptive immunity to SARS-CoV-2 with the actively updated repository providing a resource for the scientific community urgently needed to inform therapeutic concepts and vaccine development.

The induction and function of the anti-inflammatory fate of TH17 cells

T_H17 cells exemplify environmental immune adaptation: they can acquire both a pathogenic and an anti-inflammatory fate. However, it is not known whether the anti-inflammatory fate is merely a vestigial trait, or whether it serves to preserve the integrity of the host tissues. Here we show that the capacity of T_H17 cells to acquire an anti-inflammatory fate is necessary to sustain immunological tolerance, yet it impairs immune protection against S. aureus. Additionally, we find that TGF-β signalling via Smad3/Smad4 is sufficient for the expression of the anti-inflammatory cytokine, IL-10, in T_H17 cells. Our data thus indicate a key function of T_H17 cell plasticity in maintaining immune homeostasis, and dissect the molecular mechanisms explaining the functional flexibility of T_H17 cells with regard to environmental changes.

CD4⁺ T helper cells producing IL-17A (T_H17 cells) can take on pathogenic or anti-inflammatory functions in context-specific manners. Here the authors show that the anti-inflammatory fate of T_H17 cells contributes, via TGF-β signaling and induction of IL-10, to host immune tolerance, but also simultaneously dampens protective immunity against S. aureus.

Immune System Remodelling by Prenatal Betamethasone: Effects on β-Cells and Type 1 Diabetes

Type 1 diabetes (T1D) is a multifactorial disease of unknown aetiology. Studies focusing on environment-related prenatal changes, which might have an influence on the development of T1D, are still missing. Drugs, such as betamethasone, are used during this critical period without exploring possible effects later in life. Betamethasone can interact with the development and function of the two main players in T1D, the immune system and the pancreatic β-cells. Short-term or persistent changes in any of these two players may influence the initiation of the autoimmune reaction against β-cells. In this review, we focus on the ability of betamethasone to induce alterations in the immune system, impairing the recognition of autoantigens. At the same time, betamethasone affects β-cell gene expression and apoptosis rate, reducing the danger signals that will attract unwanted attention from the immune system. These effects may synergise to hinder the autoimmune attack. In this review, we compile scattered evidence to provide a better understanding of the basic relationship between betamethasone and T1D, laying the foundation for future studies on human cohorts that will help to fully grasp the role of betamethasone in the development of T1D.

Generation and Function of Non-cell-bound CD73 in Inflammation

Extracellular adenine nucleotides participate in cell-to-cell communication and modulate the immune response. The concerted action of ectonucleotidases CD39 and CD73 plays a major role in the local production of anti-inflammatory adenosine, but both ectonucleotidases are rarely co-expressed by human T cells. The expression of CD39 on T cells increases upon T cell activation and is high at sites of inflammation. CD73, in contrast, disappears from the cellular membrane after activation. The possibility that CD73 could act in trans would resolve the conundrum of both enzymes being co-expressed for the degradation of ATP and the generation of adenosine. An enzymatically active soluble form of CD73 has been reported, and AMPase activity has been detected in body fluids of patients with inflammation and cancer. It is not yet clear how CD73, a glycosylphosphatidylinositol (GPI)-anchored protein, is released from the cell membrane, but plausible mechanisms include cleavage by metalloproteinases and shedding mediated by cell-associated phospholipases. Importantly, like many other GPI-anchored proteins, CD73 at the cell membrane is preferentially localized in detergent-resistant domains or lipid rafts, which often contribute to extracellular vesicles (EVs). Indeed, CD73-containing vesicles of different size and origin and with immunomodulatory function have been found in the tumor microenvironment. The occurrence of CD73 as non-cell-bound molecule widens the range of action of this enzyme at sites of inflammation. In this review, we will discuss the generation of non-cell-bound CD73 and its physiological role in inflammation.

Inflammatory Phenotype of Intrahepatic Sulfatide-Reactive Type II NKT Cells in Humans With Autoimmune Hepatitis

Background: Natural Killer T (NKT) cells are CD1d-restricted innate-like T cells that can rapidly release stored cytokines upon recognition of lipid antigens. In mice, type I NKT cells seem to promote liver inflammation, whereas type II NKT cells seem to restrict hepatitis. Here, we aimed at characterizing the role of human type I and type II NKT in patients with autoimmune hepatitis (AIH).

Methods: NKT cells were analyzed by flow cytometry in peripheral blood and liver of AIH patients and control groups. α-galactosylceramide-loaded or sulfatide-loaded tetramers were used to detect type I or II NKT cells, respectively. Hepatic CD1d was stained by in situ-hybridization of liver biopsies.

Results and Conclusions: Type II NKT cells were more prevalent in human peripheral blood and liver than type I NKT cells. In AIH patients, the frequency of sulfatide-reactive type II NKT cells was significantly increased in peripheral blood (0.11% of peripheral blood leukocytes) and liver (3.78% of intrahepatic leukocytes) compared to healthy individuals (0.05% and 1.82%) and patients with drug-induced liver injury (0.06% and 2.03%; p < 0.05). Intrahepatic type II NKT cells of AIH patients had a different cytokine profile than healthy subjects with an increased frequency of TNFα (77.8% vs. 59.1%, p < 0.05), decreased IFNγ (32.7% vs. 63.0%, p < 0.05) and a complete lack of IL-4 expressing cells (0% vs. 2.1%, p < 0.05). T cells in portal tracts expressed significantly more CD1d-RNA in AIH livers compared to controls. This study supports that in contrast to their assumed protective role in mice, human intrahepatic, sulfatide-reactive type II NKT cells displayed a proinflammatory cytokine profile in patients with AIH. Infiltrating T cells in portal areas of AIH patients overexpressed CD1d and could thereby activate type II NKT cells.

Prenatal Betamethasone interferes with immune system development and alters target cells in autoimmune diabetes

Non-genetic factors are crucial in the pathogenesis of type 1 diabetes (T1D), a disease caused by autoimmunity against insulin-producing β-cells. Exposure to medications in the prenatal period may influence the immune system maturation, thus altering self-tolerance. Prenatal administration of betamethasone –a synthetic glucocorticoid given to women at risk of preterm delivery– may affect the development of T1D. It has been previously demonstrated that prenatal betamethasone administration protects offspring from T1D development in nonobese diabetic (NOD) mice. The direct effect of betamethasone on the immature and mature immune system of NOD mice and on target β-cells is analysed in this paper. In vitro, betamethasone decreased lymphocyte viability and induced maturation-resistant dendritic cells, which in turn impaired γδ T cell proliferation and decreased IL-17 production. Prenatal betamethasone exposure caused thymus hypotrophy in newborn mice as well as alterations in immune cells subsets. Furthermore, betamethasone decreased β-cell growth, reduced C-peptide secretion and altered the expression of genes related to autoimmunity, metabolism and islet mass in T1D target tissue. These results support the protection against T1D in the betamethasone-treated offspring and demonstrate that this drug alters the developing immune system and β-cells. Understanding how betamethasone generates self-tolerance could have potential clinical relevance in T1D.

Basic clinical features do not predict dopamine transporter binding in idiopathic REM behavior disorder

REM sleep behavior disorder (RBD) is strongly associated with development of Parkinson’s Disease and other α-synuclein-related disorders. Dopamine transporter (DAT) binding deficit predicts conversion to α-synuclein-related disorders in individuals with RBD. In turn, identifying which individuals with RBD have the highest likelihood of having abnormal DAT binding would be useful. The objective of this analysis was to examine if there are basic clinical predictors of DAT deficit in RBD. Participants referred for inclusion in the RBD cohort of the Parkinson Progression Markers Initiative were included. Assessments at the screening visit including DAT SPECT imaging, physical examination, cognitive function screen, and questionnaire-based non-motor assessment. The group with DAT binding deficit (n = 49) was compared to those without (n = 26). There were no significant differences in demographic or clinical features between the two groups. When recruiting RBD cohorts enriched for high risk of neurodegenerative disorders, our data support the need for objective biomarker assessments.

The clinical characteristics of patients with rapid eye movement sleep behavior disorder (RBD) are not associated with reduced dopamine transporter binding, an established imaging biomarker of Parkinson’s Disease (PD). Because around 80 percent of patients with RBD develop PD, there is great hope that research on these patients will help uncover early signs of the disease and guide the development of neuroprotective therapies. Lana Chahine at The University of Pittsburgh, USA, and colleagues in the Parkinson Progression Markers Initiative (PPMI) Sleep Working Group analyzed the clinical features of 75 individuals with RBD. They found no significant differences in demographic features or in motor and non-motor symptoms between RBD patients with dopamine transporter binding deficit and those without. These findings highlight the need to assess dopamine transporter binding to determine the future risk of PD.

BCL11B mutations in patients affected by a neurodevelopmental disorder with reduced type 2 innate lymphoid cells

The transcription factor BCL11B is essential for development of the nervous and the immune system, and Bcl11b deficiency results in structural brain defects, reduced learning capacity, and impaired immune cell development in mice. However, the precise role of BCL11B in humans is largely unexplored, except for a single patient with a BCL11B missense mutation, affected by multisystem anomalies and profound immune deficiency. Using massively parallel sequencing we identified 13 patients bearing heterozygous germline alterations in BCL11B. Notably, all of them are affected by global developmental delay with speech impairment and intellectual disability; however, none displayed overt clinical signs of immune deficiency. Six frameshift mutations, two nonsense mutations, one missense mutation, and two chromosomal rearrangements resulting in diminished BCL11B expression, arose de novo. A further frameshift mutation was transmitted from a similarly affected mother. Interestingly, the most severely affected patient harbours a missense mutation within a zinc-finger domain of BCL11B, probably affecting the DNA-binding structural interface, similar to the recently published patient. Furthermore, the most C-terminally located premature termination codon mutation fails to rescue the progenitor cell proliferation defect in hippocampal slice cultures from Bcl11b-deficient mice. Concerning the role of BCL11B in the immune system, extensive immune phenotyping of our patients revealed alterations in the T cell compartment and lack of peripheral type 2 innate lymphoid cells (ILC2s), consistent with the findings described in Bcl11b-deficient mice. Unsupervised analysis of 102 T lymphocyte subpopulations showed that the patients clearly cluster apart from healthy children, further supporting the common aetiology of the disorder. Taken together, we show here that mutations leading either to BCL11B haploinsufficiency or to a truncated BCL11B protein clinically cause a non-syndromic neurodevelopmental delay. In addition, we suggest that missense mutations affecting specific sites within zinc-finger domains might result in distinct and more severe clinical outcomes.

CD39 is upregulated during activation of mouse and human T cells and attenuates the immune response to Listeria monocytogenes

The ectoenzymes CD39 and CD73 degrade extracellular ATP to adenosine. ATP is released by stressed or damaged cells and provides pro-inflammatory signals to immune cells through P2 receptors. Adenosine, on the other hand, suppresses immune cells by stimulating P1 receptors. Thus, CD39 and CD73 can shape the quality of immune responses. Here we demonstrate that upregulation of CD39 is a consistent feature of activated conventional CD4⁺ and CD8⁺ T cells. Following stimulation in vitro, CD4⁺ and CD8⁺ T cells from human blood gained surface expression of CD39 but displayed only low levels of CD73. Activated human T cells from inflamed joints largely presented with a CD39⁺CD73^— phenotype. In line, in spleens of mice with acute Listeria monocytogenes, listeria-specific CD4⁺ and CD8⁺ T cells acquired a CD39⁺CD73^— phenotype. To test the function of CD39 in control of bacterial infection, CD39-deficient (CD39^-/-) mice were infected with L. monocytogenes. CD39^-/- mice showed better initial control of L. monocytogenes, which was associated with enhanced production of inflammatory cytokines. In the late stage of infection, CD39^-/- mice accumulated more listeria-specific CD8⁺ T cells in the spleen than wildtype animals suggesting that CD39 attenuates the CD8⁺ T-cell response to infection. In conclusion, our results demonstrate that CD39 is upregulated on conventional CD4⁺ and CD8⁺ T cells at sites of acute infection and inflammation, and that CD39 dampens responses to bacterial infection.