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author:("Boyman, our")
1.  Human natural killer cells prevent infectious mononucleosis features by targeting lytic Epstein-Barr virus infection 
Cell reports  2013;5(6):1489-1498.
Primary infection with the human oncogenic Epstein Barr virus (EBV) can result in infectious mononucleosis (IM), a self-limiting disease caused by massive lymphocyte expansion, which predisposes for the development of distinct EBV-associated lymphomas. It remains unclear why some individuals experience this symptomatic primary EBV infection, while the majority acquires the virus asymptomatically. Using a mouse model with reconstituted human immune system components, we show here that depletion of human natural killer (NK) cells enhances IM symptoms and promotes EBV-associated tumorigenesis, mainly due to loss of immune control over lytic EBV infection. These data suggest that failure of innate immune control by human NK cells augments symptomatic lytic EBV infection, which drives lymphocyte expansion and predisposes for EBV-associated malignancies.
PMCID: PMC3895765  PMID: 24360958
humanized mice; CD8+ T cells; lymphoma; BZLF1; NKp46
2.  Limitations of IL-2 and Rapamycin in Immunotherapy of Type 1 Diabetes 
Diabetes  2013;62(9):3120-3131.
Administration of low-dose interleukin-2 (IL-2) alone or combined with rapamycin (RAPA) prevents hyperglycemia in NOD mice. Also, low-dose IL-2 cures recent-onset type 1 diabetes (T1D) in NOD mice, partially by boosting pancreatic regulatory T cells (Treg cells). These approaches are currently being evaluated in humans. Our objective was to study the effect of higher IL-2 doses (250,000–500,000 IU daily) as well as low-dose IL-2 (25,000 IU daily) and RAPA (1 mg/kg daily) (RAPA/IL-2) combination. We show that, despite further boosting of Treg cells, high doses of IL-2 rapidly precipitated T1D in prediabetic female and male mice and increased myeloid cells in the pancreas. Also, we observed that RAPA counteracted IL-2 effects on Treg cells, failed to control IL-2–boosted NK cells, and broke IL-2–induced tolerance in a reversible way. Notably, the RAPA/IL-2 combination failure to cure T1D was associated with an unexpected deleterious effect on glucose homeostasis at multiple levels, including β-cell division, glucose tolerance, and liver glucose metabolism. Our data help to understand the therapeutic limitations of IL-2 alone or RAPA/IL-2 combination and could lead to the design of improved therapies for T1D.
PMCID: PMC3749335  PMID: 23670972
3.  Cytokine Complex–expanded Natural Killer Cells Improve Allogeneic Lung Transplant Function via Depletion of Donor Dendritic Cells 
Rationale: Natural killer (NK) cells are innate lymphocytes that target virus-infected and tumor cells. Much less is known about their ability to limit adaptive immune responses.
Objectives: Thus, we investigated to what extent NK cells can influence mouse lung allograft rejection.
Methods: For this purpose, we employed an orthotopic lung transplantation model in mice.
Measurements and Main Results: We demonstrate here that NK cells infiltrate mouse lung allografts before T cells and thereby diminished allograft inflammation, and that NK-cell deficiency enhanced allograft rejection. In contrast, expansion of recipient NK cells through IL-15/IL-15Rα complex treatment resulted in decreased T-cell infiltration and alloreactive T-cell priming as well as improved function of the allogeneic lung transplant. Only perforin-competent, but not perforin-deficient, NK cells were able to transfer these beneficial effects into transplanted NK cell–deficient IL-15Rα−/− mice. These NK cells killed allogeneic dendritic cells (DCs) in vitro and significantly decreased the number of allogeneic DCs in transplanted lungs in vivo. Furthermore, DC-depleted lung allografts presented decreased signs of rejection.
Conclusions: These results suggest that NK cells favor allograft acceptance by depleting donor-derived DCs, which otherwise would prime alloreactive T-cell responses. Thus, conditioning regimens that augment NK-cell reactivity should be clinically explored to prepare lung allograft recipients.
PMCID: PMC3734612  PMID: 23590269
natural killer cells; dendritic cells; lung; mouse transplantation; acute rejection
4.  Epidermal IL-15Rα acts as an endogenous antagonist of psoriasiform inflammation in mouse and man 
The Journal of Experimental Medicine  2013;210(10):2105-2117.
Epidermal IL-15Rα, shed by keratinocytes upon stimulation with inflammatory cytokines, counteracts IL-15–induced proliferation of IL-17–producing T cells to dampen psoriatic skin disease.
Stromal cells at epithelial surfaces contribute to innate immunity by sensing environmental danger signals and producing proinflammatory cytokines. However, the role of stromal cells in controlling local inflammation is unknown. We show that endogenous soluble IL-15 receptor α (IL-15Rα) derived from epidermal stroma, notably keratinocytes, protects against dendritic cell/IL-15-mediated, T cell-driven skin inflammation in vivo, and is relevant to human psoriasis. Selective lack of IL-15Rα on stromal epidermal cells exacerbated psoriasiform inflammation in animals. Epidermal IL-15Rα was shed by keratinocytes via proteolytic cleavage by matrix metalloproteinases upon stimulation with proinflammatory cytokines to counteract IL-15–induced proliferation of IL-17+ αβ and γδ T cells and production of TNF, IL-23, IL-17, and IL-22 during skin inflammation. Notably, administration of soluble IL-15Rα was able to repress secretion of IL-1β, IL-6, and TNF by keratinocytes, dampen expansion of IL-17+ αβ and γδ T cells in vivo, and prevent psoriasis in two mouse models, including human xenograft AGR mice. Serum levels of soluble IL-15Rα negatively correlated with disease severity, and levels rose upon successful treatment of psoriasis in patients. Thus, stressed epidermal stromal cells use soluble IL-15Rα to dampen chronic inflammatory skin disease.
PMCID: PMC3782049  PMID: 24019554
5.  Homeostatic maintenance of T cells and natural killer cells 
Homeostasis in the immune system encompasses the mechanisms governing maintenance of a functional and diverse pool of lymphocytes, thus guaranteeing immunity to pathogens while remaining self-tolerant. Antigen-naïve T cells rely on survival signals through contact with self-peptide-loaded major histocompatibility complex (MHC) molecules plus interleukin (IL)-7. Conversely, antigen-experienced (memory) T cells are typically MHC-independent and they survive and undergo periodic homeostatic proliferation through contact with both IL-7 and IL-15. Also, non-conventional γδ T cells rely on a mix of IL-7 and IL-15 for their homeostasis, whereas natural killer cells are mainly dependent on contact with IL-15. Homeostasis of CD4+ T regulatory cells is different in being chiefly regulated by contact with IL-2. Notably, increased levels of these cytokines cause expansion of responsive lymphocytes, such as found in lymphopenic hosts or following cytokine injection, whereas reduced cytokine levels cause a decline in cell numbers.
PMCID: PMC3909665  PMID: 22460580
CD4+ T cell; CD8+ T cell; NK cell; IL-4; IL-10; IL-21; Interferon; TSLP
6.  Research needs in allergy: an EAACI position paper, in collaboration with EFA 
Papadopoulos, Nikolaos G | Agache, Ioana | Bavbek, Sevim | Bilo, Beatrice M | Braido, Fulvio | Cardona, Victoria | Custovic, Adnan | deMonchy, Jan | Demoly, Pascal | Eigenmann, Philippe | Gayraud, Jacques | Grattan, Clive | Heffler, Enrico | Hellings, Peter W | Jutel, Marek | Knol, Edward | Lötvall, Jan | Muraro, Antonella | Poulsen, Lars K | Roberts, Graham | Schmid-Grendelmeier, Peter | Skevaki, Chrysanthi | Triggiani, Massimo | vanRee, Ronald | Werfel, Thomas | Flood, Breda | Palkonen, Susanna | Savli, Roberta | Allegri, Pia | Annesi-Maesano, Isabella | Annunziato, Francesco | Antolin-Amerigo, Dario | Apfelbacher, Christian | Blanca, Miguel | Bogacka, Ewa | Bonadonna, Patrizia | Bonini, Matteo | Boyman, Onur | Brockow, Knut | Burney, Peter | Buters, Jeroen | Butiene, Indre | Calderon, Moises | Cardell, Lars Olaf | Caubet, Jean-Christoph | Celenk, Sevcan | Cichocka-Jarosz, Ewa | Cingi, Cemal | Couto, Mariana | deJong, Nicolette | Del Giacco, Stefano | Douladiris, Nikolaos | Fassio, Filippo | Fauquert, Jean-Luc | Fernandez, Javier | Rivas, Montserrat Fernandez | Ferrer, Marta | Flohr, Carsten | Gardner, James | Genuneit, Jon | Gevaert, Philippe | Groblewska, Anna | Hamelmann, Eckard | Hoffmann, Hans Jürgen | Hoffmann-Sommergruber, Karin | Hovhannisyan, Lilit | Hox, Valérie | Jahnsen, Frode L | Kalayci, Ömer | Kalpaklioglu, Ayse Füsun | Kleine-Tebbe, Jörg | Konstantinou, George | Kurowski, Marcin | Lau, Susanne | Lauener, Roger | Lauerma, Antti | Logan, Kirsty | Magnan, Antoine | Makowska, Joanna | Makrinioti, Heidi | Mangina, Paraskevi | Manole, Felicia | Mari, Adriano | Mazon, Angel | Mills, Clare | Mingomataj, ErvinÇ | Niggemann, Bodo | Nilsson, Gunnar | Ollert, Markus | O'Mahony, Liam | O'Neil, Serena | Pala, Gianni | Papi, Alberto | Passalacqua, Gianni | Perkin, Michael | Pfaar, Oliver | Pitsios, Constantinos | Quirce, Santiago | Raap, Ulrike | Raulf-Heimsoth, Monika | Rhyner, Claudio | Robson-Ansley, Paula | Alves, Rodrigo Rodrigues | Roje, Zeljka | Rondon, Carmen | Rudzeviciene, Odilija | Ruëff, Franziska | Rukhadze, Maia | Rumi, Gabriele | Sackesen, Cansin | Santos, Alexandra F | Santucci, Annalisa | Scharf, Christian | Schmidt-Weber, Carsten | Schnyder, Benno | Schwarze, Jürgen | Senna, Gianenrico | Sergejeva, Svetlana | Seys, Sven | Siracusa, Andrea | Skypala, Isabel | Sokolowska, Milena | Spertini, Francois | Spiewak, Radoslaw | Sprikkelman, Aline | Sturm, Gunter | Swoboda, Ines | Terreehorst, Ingrid | Toskala, Elina | Traidl-Hoffmann, Claudia | Venter, Carina | Vlieg-Boerstra, Berber | Whitacker, Paul | Worm, Margitta | Xepapadaki, Paraskevi | Akdis, Cezmi A
In less than half a century, allergy, originally perceived as a rare disease, has become a major public health threat, today affecting the lives of more than 60 million people in Europe, and probably close to one billion worldwide, thereby heavily impacting the budgets of public health systems. More disturbingly, its prevalence and impact are on the rise, a development that has been associated with environmental and lifestyle changes accompanying the continuous process of urbanization and globalization. Therefore, there is an urgent need to prioritize and concert research efforts in the field of allergy, in order to achieve sustainable results on prevention, diagnosis and treatment of this most prevalent chronic disease of the 21st century.
The European Academy of Allergy and Clinical Immunology (EAACI) is the leading professional organization in the field of allergy, promoting excellence in clinical care, education, training and basic and translational research, all with the ultimate goal of improving the health of allergic patients. The European Federation of Allergy and Airways Diseases Patients’ Associations (EFA) is a non-profit network of allergy, asthma and Chronic Obstructive Pulmonary Disorder (COPD) patients’ organizations. In support of their missions, the present EAACI Position Paper, in collaboration with EFA, highlights the most important research needs in the field of allergy to serve as key recommendations for future research funding at the national and European levels.
Although allergies may involve almost every organ of the body and an array of diverse external factors act as triggers, there are several common themes that need to be prioritized in research efforts. As in many other chronic diseases, effective prevention, curative treatment and accurate, rapid diagnosis represent major unmet needs. Detailed phenotyping/endotyping stands out as widely required in order to arrange or re-categorize clinical syndromes into more coherent, uniform and treatment-responsive groups. Research efforts to unveil the basic pathophysiologic pathways and mechanisms, thus leading to the comprehension and resolution of the pathophysiologic complexity of allergies will allow for the design of novel patient-oriented diagnostic and treatment protocols. Several allergic diseases require well-controlled epidemiological description and surveillance, using disease registries, pharmacoeconomic evaluation, as well as large biobanks. Additionally, there is a need for extensive studies to bring promising new biotechnological innovations, such as biological agents, vaccines of modified allergen molecules and engineered components for allergy diagnosis, closer to clinical practice. Finally, particular attention should be paid to the difficult-to-manage, precarious and costly severe disease forms and/or exacerbations. Nonetheless, currently arising treatments, mainly in the fields of immunotherapy and biologicals, hold great promise for targeted and causal management of allergic conditions. Active involvement of all stakeholders, including Patient Organizations and policy makers are necessary to achieve the aims emphasized herein.
PMCID: PMC3539924  PMID: 23121771
Allergy; Allergic diseases; Policy; Research needs; Research funding; Europe
7.  Exploiting a natural conformational switch to engineer an Interleukin-2 superkine 
Nature  2012;484(7395):529-533.
The immunostimulatory cytokine interleukin-2 (IL-2) is a growth factor for a wide range of leukocytes, including T cells and natural killer (NK) cells1–3. Considerable effort has been invested using IL-2 as a therapeutic agent for a variety of immune disorders ranging from AIDS to cancer. However, adverse effects have limited its use in the clinic. On activated T cells, IL-2 signals through a quaternary “high affinity” receptor complex consisting of IL-2, IL-2Rα (termed CD25), IL-2Rβ, and γc4–8. Naïve T cells express only a low density of IL-2Rβ and γc, and are therefore relatively insensitive to IL-2, but acquire sensitivity after CD25 expression, which captures the cytokine and presents it to IL-2Rβ andγc. Here, using in vitro evolution, we eliminated IL-2’s functional requirement for CD25 expression by engineering an IL-2 “superkine” (termed super-2) with increased binding affinity for IL-2Rβ. Crystal structures of super-2 in free and receptor-bound forms showed that the evolved mutations are principally in the core of the cytokine, and molecular dynamics simulations indicated that the evolved mutations stabilized IL-2, including a flexible helix in the IL-2Rβ binding site, into an optimized receptor-binding conformation resembling that when bound to CD25. The evolved mutations in super-2 recapitulated the functional role of CD25 by eliciting potent phosphorylation of STAT5 and vigorous proliferation T cells irrespective of CD25 expression. Compared to IL-2, super-2 induced superior expansion of cytotoxic T cells, leading to improved anti-tumor responses in vivo, and elicited proportionally less expansion of T regulatory cells and reduced pulmonary edema. Collectively, we show that in vitro evolution has mimicked the functional role of CD25 in enhancing IL-2 potency and regulating target cell specificity, which has implications for immunotherapy.
PMCID: PMC3338870  PMID: 22446627
8.  In vivo expansion of T reg cells with IL-2–mAb complexes: induction of resistance to EAE and long-term acceptance of islet allografts without immunosuppression 
Via a transcription factor, Foxp3, immunoregulatory CD4+CD25+ T cells (T reg cells) play an important role in suppressing the function of other T cells. Adoptively transferring high numbers of T reg cells can reduce the intensity of the immune response, thereby providing an attractive prospect for inducing tolerance. Extending our previous findings, we describe an in vivo approach for inducing rapid expansion of T reg cells by injecting mice with interleukin (IL)-2 mixed with a particular IL-2 monoclonal antibody (mAb). Injection of these IL-2–IL-2 mAb complexes for a short period of 3 d induces a marked (>10-fold) increase in T reg cell numbers in many organs, including the liver and gut as well as the spleen and lymph nodes, and a modest increase in the thymus. The expanded T reg cells survive for 1–2 wk and are highly activated and display superior suppressive function. Pretreating with the IL-2–IL-2 mAb complexes renders the mice resistant to induction of experimental autoimmune encephalomyelitis; combined with rapamycin, the complexes can also be used to treat ongoing disease. In addition, pretreating mice with the complexes induces tolerance to fully major histocompatibility complex–incompatible pancreatic islets in the absence of immunosuppression. Tolerance is robust and the majority of grafts are accepted indefinitely. The approach described for T reg cell expansion has clinical potential for treating autoimmune disease and promoting organ transplantation.
PMCID: PMC2715127  PMID: 19332874
9.  An intense form of homeostatic proliferation of naive CD8+ cells driven by IL-2 
The Journal of Experimental Medicine  2007;204(8):1787-1801.
In conditions of T lymphopenia, interleukin (IL) 7 levels rise and, via T cell receptor for antigen–self–major histocompatibility complex (MHC) interaction, induce residual naive T cells to proliferate. This pattern of lymphopenia-induced “homeostatic” proliferation is typically quite slow and causes a gradual increase in total T cell numbers and differentiation into cells with features of memory cells. In contrast, we describe a novel form of homeostatic proliferation that occurs when naive T cells encounter raised levels of IL-2 and IL-15 in vivo. In this situation, CD8+ T cells undergo massive expansion and rapid differentiation into effector cells, thus closely resembling the T cell response to foreign antigens. However, the responses induced by IL-2/IL-15 are not seen in MHC-deficient hosts, implying that the responses are driven by self-ligands. Hence, homeostatic proliferation of naive T cells can be either slow or fast, with the quality of the response to self being dictated by the particular cytokine (IL-7 vs. IL-2/IL-15) concerned. The relevance of the data to the gradual transition of naive T cells into memory-phenotype (MP) cells with age is discussed.
PMCID: PMC2118670  PMID: 17664294
10.  GATA3-Driven Th2 Responses Inhibit TGF-β1–Induced FOXP3 Expression and the Formation of Regulatory T Cells 
PLoS Biology  2007;5(12):e329.
Transcription factors act in concert to induce lineage commitment towards Th1, Th2, or T regulatory (Treg) cells, and their counter-regulatory mechanisms were shown to be critical for polarization between Th1 and Th2 phenotypes. FOXP3 is an essential transcription factor for natural, thymus-derived (nTreg) and inducible Treg (iTreg) commitment; however, the mechanisms regulating its expression are as yet unknown. We describe a mechanism controlling iTreg polarization, which is overruled by the Th2 differentiation pathway. We demonstrated that interleukin 4 (IL-4) present at the time of T cell priming inhibits FOXP3. This inhibitory mechanism was also confirmed in Th2 cells and in T cells of transgenic mice overexpressing GATA-3 in T cells, which are shown to be deficient in transforming growth factor (TGF)-β–mediated FOXP3 induction. This inhibition is mediated by direct binding of GATA3 to the FOXP3 promoter, which represses its transactivation process. Therefore, this study provides a new understanding of tolerance development, controlled by a type 2 immune response. IL-4 treatment in mice reduces iTreg cell frequency, highlighting that therapeutic approaches that target IL-4 or GATA3 might provide new preventive strategies facilitating tolerance induction particularly in Th2-mediated diseases, such as allergy.
Author Summary
Specific immune responses against foreign or autologous antigens are driven by specialized epitope-specific T cells, whose numbers expand upon recognition of antigen found on professional antigen-presenting cells. The subsequent maturation process involves the differentiation of certain T cell phenotypes such as pro-inflammatory cells (Th1, Th2, Th17) or regulatory T (Treg) cells, which serve to keep the immune response in check. The current study focuses on the role of two key transcription factors—FOXP3 and GATA3—in controlling the commitment of these cells. We demonstrate that the Th2 cytokine IL-4 inhibits the induction of FOXP3 and thus inhibits the generation of inducible Treg cells. We show that IL-4–induced GATA3 mediates FOXP3 inhibition by directly binding to a GATA element in the FOXP3 promoter. We hypothesize that therapeutic agents aimed at neutralizing IL-4 could be a novel strategy to facilitate inducible Treg cell generation and thus promotion of tolerance in allergies and other Th2-dominated diseases.
It is shown that Th2 responses prevent the generation of inducible Tregs. This is mediated by IL-4 induction of GATA3, which binds directly to and represses the FOXP3 promoter. This mechanism is likely to be relevant in the induction of immunotolerance, particularly in allergic diseases.
PMCID: PMC2222968  PMID: 18162042
11.  A major histocompatibility complex class I–dependent subset of memory phenotype CD8+ cells 
The Journal of Experimental Medicine  2006;203(7):1817-1825.
Most memory phenotype (MP) CD44hi CD8+ cells are resting interleukin (IL)-15–dependent cells characterized by high expression of the IL-2/IL-15 receptor β (CD122). However, some MP CD8+ cells have a CD122lo phenotype and are IL-15 independent. Here, evidence is presented that the CD122lo subset of MP CD8+ cells is controlled largely by major histocompatibility complex (MHC) class I molecules. Many of these cells display surface markers typical of recently activated T cells (CD62Llo, CD69hi, CD43hi, and CD127lo) and show a high rate of background proliferation. Cells with this phenotype are highly enriched in common γ chain–deficient mice and absent from MHC-I−/− mice. Unlike CD122hi CD8+ cells, CD122lo MP CD8+ cells survive poorly after transfer to MHC-I−/− hosts and cease to proliferate. Although distinctly different from typical antigen-specific memory cells, CD122lo MP CD8+ cells closely resemble the antigen-dependent memory CD8+ cells found in chronic viral infections.
PMCID: PMC2118360  PMID: 16818671
12.  Plasmacytoid predendritic cells initiate psoriasis through interferon-α production 
Psoriasis is one of the most common T cell–mediated autoimmune diseases in humans. Although a role for the innate immune system in driving the autoimmune T cell cascade has been proposed, its nature remains elusive. We show that plasmacytoid predendritic cells (PDCs), the natural interferon (IFN)-α–producing cells, infiltrate the skin of psoriatic patients and become activated to produce IFN-α early during disease formation. In a xenograft model of human psoriasis, we demonstrate that blocking IFN-α signaling or inhibiting the ability of PDCs to produce IFN-α prevented the T cell–dependent development of psoriasis. Furthermore, IFN-α reconstitution experiments demonstrated that PDC-derived IFN-α is essential to drive the development of psoriasis in vivo. These findings uncover a novel innate immune pathway for triggering a common human autoimmune disease and suggest that PDCs and PDC-derived IFN-α represent potential early targets for the treatment of psoriasis.
PMCID: PMC2212894  PMID: 15998792
13.  Spontaneous Development of Psoriasis in a New Animal Model Shows an Essential Role for Resident T Cells and Tumor Necrosis Factor-α 
Psoriasis is a common T cell–mediated autoimmune disorder where primary onset of skin lesions is followed by chronic relapses. Progress in defining the mechanism for initiation of pathological events has been hampered by the lack of a relevant experimental model in which psoriasis develops spontaneously. We present a new animal model in which skin lesions spontaneously developed when symptomless prepsoriatic human skin was engrafted onto AGR129 mice, deficient in type I and type II interferon receptors and for the recombination activating gene 2. Upon engraftment, resident human T cells in prepsoriatic skin underwent local proliferation. T cell proliferation was crucial for development of a psoriatic phenotype because blocking of T cells led to inhibition of psoriasis development. Tumor necrosis factor-α was a key regulator of local T cell proliferation and subsequent disease development. Our observations highlight the importance of resident T cells in the context of lesional tumor necrosis factor-α production during development of a psoriatic lesion. These findings underline the importance of resident immune cells in psoriasis and will have implications for new therapeutic strategies for psoriasis and other T cell–mediated diseases.
PMCID: PMC2213300  PMID: 14981113
autoimmunity; immunotherapy; inflammation; mouse model; skin

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