PAR-1 contributes to the innate immune response during viral infection

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Abstract

Coagulation is a host defense system that limits the spread of pathogens. Coagulation proteases, such as thrombin, also activate cells by cleaving PARs. In this study, we analyzed the role of PAR-1 in coxsackievirus B3–induced (CVB3-induced) myocarditis and influenza A infection. CVB3-infected Par1^–/– mice expressed reduced levels of IFN-β and CXCL10 during the early phase of infection compared with Par1^+/+ mice that resulted in higher viral loads and cardiac injury at day 8 after infection. Inhibition of either tissue factor or thrombin in WT mice also significantly increased CVB3 levels in the heart and cardiac injury compared with controls. BM transplantation experiments demonstrated that PAR-1 in nonhematopoietic cells protected mice from CVB3 infection. Transgenic mice overexpressing PAR-1 in cardiomyocytes had reduced CVB3-induced myocarditis. We found that cooperative signaling between PAR-1 and TLR3 in mouse cardiac fibroblasts enhanced activation of p38 and induction of IFN-β and CXCL10 expression. Par1^–/– mice also had decreased CXCL10 expression and increased viral levels in the lung after influenza A infection compared with Par1^+/+ mice. Our results indicate that the tissue factor/thrombin/PAR-1 pathway enhances IFN-β expression and contributes to the innate immune response during single-stranded RNA viral infection.

Authors

Silvio Antoniak, A. Phillip Owens III, Martin Baunacke, Julie C. Williams, Rebecca D. Lee, Alice Weithäuser, Patricia A. Sheridan, Ronny Malz, James P. Luyendyk, Denise A. Esserman, JoAnn Trejo, Daniel Kirchhofer, Burns C. Blaxall, Rafal Pawlinski, Melinda A. Beck, Ursula Rauch, Nigel Mackman

SHP-1 phosphatase activity counteracts increased T cell receptor affinity

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Abstract

Anti-self/tumor T cell function can be improved by increasing TCR-peptide MHC (pMHC) affinity within physiological limits, but paradoxically further increases (K_d < 1 μM) lead to drastic functional declines. Using human CD8⁺ T cells engineered with TCRs of incremental affinity for the tumor antigen HLA-A2/NY-ESO-1, we investigated the molecular mechanisms underlying this high-affinity–associated loss of function. As compared with cells expressing TCR affinities generating optimal function (K_d = 5 to 1 μM), those with supraphysiological affinity (K_d = 1 μM to 15 nM) showed impaired gene expression, signaling, and surface expression of activatory/costimulatory receptors. Preferential expression of the inhibitory receptor programmed cell death-1 (PD-1) was limited to T cells with the highest TCR affinity, correlating with full functional recovery upon PD-1 ligand 1 (PD-L1) blockade. In contrast, upregulation of the Src homology 2 domain-containing phosphatase 1 (SHP-1/PTPN6) was broad, with gradually enhanced expression in CD8⁺ T cells with increasing TCR affinities. Consequently, pharmacological inhibition of SHP-1 with sodium stibogluconate augmented the function of all engineered T cells, and this correlated with the TCR affinity–dependent levels of SHP-1. These data highlight an unexpected and global role of SHP-1 in regulating CD8⁺ T cell activation and responsiveness and support the development of therapies inhibiting protein tyrosine phosphatases to enhance T cell–mediated immunity.

Authors

Michael Hebeisen, Lukas Baitsch, Danilo Presotto, Petra Baumgaertner, Pedro Romero, Olivier Michielin, Daniel E. Speiser, Nathalie Rufer

2-photon imaging of phagocyte-mediated T cell activation in the CNS

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Abstract

Autoreactive T cells can infiltrate the CNS to cause disorders such as multiple sclerosis. In order to visualize T cell activation in the CNS, we introduced a truncated fluorescent derivative of nuclear factor of activated T cells (NFAT) as a real-time T cell activation indicator. In experimental autoimmune encephalomyelitis, a rat model of multiple sclerosis, we tracked T cells interacting with structures of the vascular blood-brain barrier (BBB). 2-photon imaging documented the cytoplasmic-nuclear translocation of fluorescent NFAT, indicative of calcium-dependent activation of the T cells in the perivascular space, but not within the vascular lumen. The activation was related to contacts with the local antigen-presenting phagocytes and was noted only in T cells with a high pathogenic potential. T cell activation implied the presentation of an autoantigen, as the weakly pathogenic T cells, which remained silent in the untreated hosts, were activated upon instillation of exogenous autoantigen. Activation did not cogently signal long-lasting arrest, as individual T cells were able to sequentially contact fresh APCs. We propose that the presentation of local autoantigen by BBB-associated APCs provides stimuli that guide autoimmune T cells to the CNS destination, enabling them to attack the target tissue.

Authors

Marija Pesic, Ingo Bartholomäus, Nikolaos I. Kyratsous, Vigo Heissmeyer, Hartmut Wekerle, Naoto Kawakami

Specialized role of migratory dendritic cells in peripheral tolerance induction

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Abstract

Harnessing DCs for immunotherapies in vivo requires the elucidation of the physiological role of distinct DC populations. Migratory DCs traffic from peripheral tissues to draining lymph nodes charged with tissue self antigens. We hypothesized that these DC populations have a specialized role in the maintenance of peripheral tolerance, specifically, to generate suppressive Foxp3⁺ Tregs. To examine the differential capacity of migratory DCs versus blood-derived lymphoid-resident DCs for Treg generation in vivo, we targeted a self antigen, myelin oligodendrocyte glycoprotein, using antibodies against cell surface receptors differentially expressed in these DC populations. Using this approach together with mouse models that lack specific DC populations, we found that migratory DCs have a superior ability to generate Tregs in vivo, which in turn drastically improve the outcome of experimental autoimmune encephalomyelitis. These results provide a rationale for the development of novel therapies targeting migratory DCs for the treatment of autoimmune diseases.

Authors

Juliana Idoyaga, Christopher Fiorese, Lori Zbytnuik, Ashira Lubkin, Jennifer Miller, Bernard Malissen, Daniel Mucida, Miriam Merad, Ralph M. Steinman

An obligate cell-intrinsic function for CD28 in Tregs

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Abstract

Tregs expressing the transcription factor FOXP3 are critical for immune homeostasis. The costimulatory molecule CD28 is required for optimal activation and function of naive T cells; however, its role in Treg function has been difficult to dissect, as CD28 is required for thymic Treg development, and blockade of CD28-ligand interactions has confounding effects in trans on nonregulatory cells. To address this question, we created Treg-specific Cd28 conditional knockout mice. Despite the presence of normal numbers of FOXP3⁺ cells, these animals accumulated large numbers of activated T cells, developed severe autoimmunity that primarily affected the skin and lungs, and failed to appropriately resolve induced experimental allergic encephalomyelitis. This in vivo functional impairment was accompanied by dampened expression of CTLA-4, PD-1, and CCR6. Disease occurrence was not due to subversion of Cd28-deficient Tregs into pathogenic cells, as complementation with normal Tregs prevented disease occurrence. Interestingly, in these “competitive” environments, Cd28-deficient Tregs exhibited a pronounced proliferative/survival disadvantage. These data demonstrate clear postmaturational roles for CD28 in FOXP3⁺ Tregs and provide mechanisms which we believe to be novel to explain how interruption of CD28-ligand interactions may enhance immune responses independent of effects on thymic development or on other cell types.

Authors

Ruan Zhang, Alexandria Huynh, Gregory Whitcher, JiHoon Chang, Jonathan S. Maltzman, Laurence A. Turka

CXCR5⁺ T helper cells mediate protective immunity against tuberculosis

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Abstract

One third of the world’s population is infected with Mycobacterium tuberculosis (Mtb). Although most infected people remain asymptomatic, they have a 10% lifetime risk of developing active tuberculosis (TB). Thus, the current challenge is to identify immune parameters that distinguish individuals with latent TB from those with active TB. Using human and experimental models of Mtb infection, we demonstrated that organized ectopic lymphoid structures containing CXCR5⁺ T cells were present in Mtb-infected lungs. In addition, we found that in experimental Mtb infection models, the presence of CXCR5⁺ T cells within ectopic lymphoid structures was associated with immune control. Furthermore, in a mouse model of Mtb infection, we showed that activated CD4⁺CXCR5⁺ T cells accumulated in Mtb-infected lungs and produced proinflammatory cytokines. Mice deficient in Cxcr5 had increased susceptibility to TB due to defective T cell localization within the lung parenchyma. We demonstrated that CXCR5 expression in T cells mediated correct T cell localization within TB granulomas, promoted efficient macrophage activation, protected against Mtb infection, and facilitated lymphoid follicle formation. These data demonstrate that CD4⁺CXCR5⁺ T cells play a protective role in the immune response against TB and highlight their potential use for future TB vaccine design and therapy.

Authors

Samantha R. Slight, Javier Rangel-Moreno, Radha Gopal, Yinyao Lin, Beth A. Fallert Junecko, Smriti Mehra, Moises Selman, Enrique Becerril-Villanueva, Javier Baquera-Heredia, Lenin Pavon, Deepak Kaushal, Todd A. Reinhart, Troy D. Randall, Shabaana A. Khader

Superior T memory stem cell persistence supports long-lived T cell memory

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Abstract

Long-lived memory T cells are able to persist in the host in the absence of antigen; however, the mechanism by which they are maintained is not well understood. Recently, a subset of human T cells, stem cell memory T cells (T_SCM cells), was shown to be self-renewing and multipotent, thereby providing a potential reservoir for T cell memory throughout life. However, their in vivo dynamics and homeostasis still remain to be defined due to the lack of suitable animal models. We identified T cells with a T_SCM phenotype and stem cell–like properties in nonhuman primates. These cells were the least-differentiated memory subset, were functionally distinct from conventional memory cells, and served as precursors of central memory. Antigen-specific T_SCM cells preferentially localized to LNs and were virtually absent from mucosal surfaces. They were generated in the acute phase of viral infection, preferentially survived in comparison with all other memory cells following elimination of antigen, and stably persisted for the long term. Thus, one mechanism for maintenance of long-term T cell memory derives from the unique homeostatic properties of T_SCM cells. Vaccination strategies designed to elicit durable cellular immunity should target the generation of T_SCM cells.

Authors

Enrico Lugli, Maria H. Dominguez, Luca Gattinoni, Pratip K. Chattopadhyay, Diane L. Bolton, Kaimei Song, Nichole R. Klatt, Jason M. Brenchley, Monica Vaccari, Emma Gostick, David A. Price, Thomas A. Waldmann, Nicholas P. Restifo, Genoveffa Franchini, Mario Roederer

Transepithelial migration of neutrophils into the lung requires TREM-1

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Abstract

Acute respiratory infections are responsible for more than 4 million deaths each year. Neutrophils play an essential role in the innate immune response to lung infection. These cells have an armamentarium of pattern recognition molecules and antimicrobial agents that identify and eliminate pathogens. In the setting of infection, neutrophil triggering receptor expressed on myeloid cells 1 (TREM-1) amplifies inflammatory signaling. Here we demonstrate for the first time that TREM-1 also plays an important role in transepithelial migration of neutrophils into the airspace. We developed a TREM-1/3–deficient mouse model of pneumonia and found that absence of TREM-1/3 markedly increased mortality following Pseudomonas aeruginosa challenge. Unexpectedly, TREM-1/3 deficiency resulted in increased local and systemic cytokine production. TREM-1/3–deficient neutrophils demonstrated intact bacterial killing, phagocytosis, and chemotaxis; however, histologic examination of TREM-1/3–deficient lungs revealed decreased neutrophil infiltration of the airways. TREM-1/3–deficient neutrophils effectively migrated across primary endothelial cell monolayers but failed to migrate across primary airway epithelia grown at the air-liquid interface. These data define a new function for TREM-1 in neutrophil migration across airway epithelial cells and suggest that it amplifies inflammation through targeted neutrophil migration into the lung.

Authors

Julia Klesney-Tait, Kathy Keck, Xiaopeng Li, Susan Gilfillan, Karel Otero, Sankar Baruah, David K. Meyerholz, Steven M. Varga, Cory J. Knudson, Thomas O. Moninger, Jessica Moreland, Joseph Zabner, Marco Colonna

IL-17A secretion by CD8⁺ T cells supports Th17-mediated autoimmune encephalomyelitis

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Abstract

IL-17–producing CD8+ T (Tc17) cells are detectible in multiple sclerosis (MS) lesions; however, their contribution to the disease is unknown. To identify functions of Tc17 cells, we induced EAE, a murine model of MS, in mice lacking IFN regulatory factor 4 (IRF4). IRF4-deficient mice failed to generate Tc17 and Th17 cells and were resistant to EAE. After adoptive transfer of WT CD8+ T cells and subsequent immunization for EAE induction in these mice, the CD8+ T cells developed a Tc17 phenotype in the periphery but could not infiltrate the CNS. Similarly, transfer of small numbers of WT CD4+ T cells alone did not evoke EAE, but when transferred together with CD8+ T cells, IL-17–producing CD4+ (Th17) T cells accumulated in the CNS and mice developed severe disease. Th17 accumulation and development of EAE required IL-17A production by CD8+ T cells, suggesting that Tc17 cells are required to promote CD4+ T cell–mediated induction of EAE. Accordingly, patients with early-stage MS harbored a greater number of Tc17 cells in the cerebrospinal fluid than in peripheral blood. Our results reveal that Tc17 cells contribute to the initiation of CNS autoimmunity in mice and humans by supporting Th17 cell pathogenicity.

Authors

Magdalena Huber, Sylvia Heink, Axel Pagenstecher, Katharina Reinhard, Josephine Ritter, Alexander Visekruna, Anna Guralnik, Nadine Bollig, Katharina Jeltsch, Christina Heinemann, Eva Wittmann, Thorsten Buch, Olivia Prazeres da Costa, Anne Brüstle, Dirk Brenner, Tak W. Mak, Hans-Willi Mittrücker, Björn Tackenberg, Thomas Kamradt, Michael Lohoff

Extrathymic development of murine T cells after bone marrow transplantation

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Abstract

Restoring T cell competence is a significant clinical challenge in patients whose thymic function is severely compromised due to age or cytoreductive conditioning. Here, we demonstrate in mice that mesenteric LNs (MLNs) support extrathymic T cell development in euthymic and athymic recipients of bone marrow transplantation (BMT). Furthermore, in aged murine BMT recipients, the contribution of the MLNs to the generation of T cells was maintained, while the contribution of the thymus was significantly impaired. Thymic impairment resulted in a proportional increase in extrathymic-derived T cell progenitors. Extrathymic development in athymic recipients generated conventional naive TCRαβ T cells with a broad Vβ repertoire and intact functional and proliferative potential. Moreover, in the absence of a functional thymus, immunity against known pathogens could be augmented using engineered precursor T cells with viral specificity. These findings demonstrate the potential of extrathymic T cell development for T cell reconstitution in patients with limited thymic function.

Authors

Amanda M. Holland, Johannes L. Zakrzewski, Jennifer J. Tsai, Alan M. Hanash, Jarrod A. Dudakov, Odette M. Smith, Mallory L. West, Natalie V. Singer, Jessie Brill, Joseph C. Sun, Marcel R.M. van den Brink