bluuebunny/crossref_metadata_2025 huggingface dataset:
Expression and Cellular Provenance of Thymic Stromal Lymphopoietin and Chemokines in Patients with Severe Asthma and Chronic Obstructive Pulmonary Disease
Authors: Ying Sun , O'Connor Brian , Ratoff Jonathan , Meng Qiu , Fang Cailong , Cousins David , Zhang Guizhen , Gu Shuyan , Gao Zhongli , Shamji Betty , Edwards Matthew J. , Lee Tak H. , Corrigan Chris J.
Published: April 2014

Asthma and chronic obstructive pulmonary disease (COPD) are associated with Th2 and Th1 differentiated T cells. The cytokine thymic stromal lymphopoietin (TSLP) promotes differentiation of Th2 T cells and secretion of chemokines which preferentially attract them. We hypothesized that there is distinct airways expression of TSLP and chemokines which preferentially attract Th1- and Th2-type T cells, and influx of T cells bearing their receptors in asthma and COPD. In situ hybridization, immunohistochemistry, and ELISA were used to examine the expression and cellular provenance of TSLP, Th2-attracting (TARC/CCL17, MDC/CCL22, I-309/CCL1), and Th1-attracting (IP-10/CXCL10, I-TAC/CXCL11) chemokines in the bronchial mucosa and bronchoalveolar lavage fluid of subjects with moderate/severe asthma, COPD, and controls. Cells expressing mRNA encoding TSLP, TARC/CCL17, MDC/CCL22, and IP-10/CXCL10, but not I-TAC/CXCL11 and I-309/CCL1, were significantly increased in severe asthma and COPD as compared with non-smoker controls (p < 0.02). This pattern was reflected in bronchoalveolar lavage fluid protein concentrations. Expression of the same chemokines was also increased in ex- and current smokers. The cellular sources of TSLP and chemokines were strikingly similar in severe asthma and COPD. The numbers of total bronchial mucosal T cells expressing the chemokine receptors CCR4, CCR8, and CXCR3 did not significantly differ in asthma, COPD, and controls. Both asthma and COPD are associated with elevated bronchial mucosal expression of TSLP and the same Th1- and Th2-attracting chemokines. Increased expression of these chemokines is not, however, associated with selective accumulation of T cells bearing their receptors.
Airway House Dust Extract Exposures Modify Allergen-Induced Airway Hypersensitivity Responses by TLR4-Dependent and Independent Pathways
Authors: Lam Diane , Ng Nicholas , Lee Steve , Batzer Glenda , Horner Anthony A.
Published: April 2014

TLR ligands and other allergen-nonspecific immunostimulatory molecules are ubiquitous in ambient air and have profound modulatory activities in animal models of allergic asthma. However, several of these molecules have been shown to promote exaggerated Th2-biased airway hypersensitivity responses (AHRs), whereas others attenuate the asthmatic phenotype. Therefore, it has proven difficult to extrapolate experimental results with purified molecules toward a more general understanding of the allergen-nonspecific immunomodulatory influence of living environments on the natural history of allergic asthma. These investigations determined how regular and intermittent airway exposures to an unpurified, but sterile house dust extract standard (HDEst) affected the OVA-specific AHR and immune status of previously Th2-sensitized mice. Low-dose daily and high-dose intermittent HDEst exposures modulated ongoing AHRs considerably, reducing eosinophil recruitment and methacholine responsiveness, while increasing neutrophilic inflammation. However, only daily airway delivery of low-dose HDEst attenuated OVA-specific Th2 cytokine production and Th2-biased AHRs to allergen challenge 1 mo later. Finally, whereas LPS mimicked many of the immunomodulatory characteristics of HDEst in this murine asthma model, daily airway HDEst delivery was highly effective in attenuating the AHR of OVA/alum-sensitized TLR4-deficient mice. Taken together, these investigations provide direct evidence that living environments contain allergen-nonspecific immunostimulatory molecules that influence the airway hypersensitivity status of allergen-sensitized mice by TLR4-dependent and independent mechanisms.
Antigen Persistence Is Required for Dendritic Cell Licensing and CD8+ T Cell Cross-Priming
Authors: Jusforgues-Saklani Hélène , Uhl Martin , Blachère Nathalie , Lemaître Fabrice , Lantz Olivier , Bousso Philippe , Braun Deborah , Moon James J. , Albert Matthew L.
Published: April 2014

It has been demonstrated that CD4+ T cells require Ag persistence to achieve effective priming, whereas CD8+ T cells are on “autopilot” after only a brief exposure. This finding presents a disturbing conundrum as it does not account for situations in which CD8+ T cells require CD4+ T cell help. We used a physiologic in vivo model to study the requirement of Ag persistence for the cross-priming of minor histocompatibility Ag-specific CD8+ T cells. We report inefficient cross-priming in situations in which male cells are rapidly cleared. Strikingly, the failure to achieve robust CD8+ T cell activation is not due to a problem with cross-presentation. In fact, by providing “extra help” in the form of dendritic cells (DCs) loaded with MHC class II peptide, it was possible to achieve robust activation of CD8+ T cells. Our data suggest that the “licensing” of cross-presenting DCs does not occur during their initial encounter with CD4+ T cells, thus accounting for the requirement for Ag persistence and suggesting that DCs make multiple interactions with CD8+ T cells during the priming phase. These findings imply that long-lived Ag is critical for efficient vaccination protocols in which the CD8+ T cell response is helper-dependent.
Apoptotic Cells Induce Immunosuppression through Dendritic Cells: Critical Roles of IFN-γ and Nitric Oxide
Authors: Ren Guangwen , Su Juanjuan , Zhao Xin , Zhang Liying , Zhang Jimin , Roberts Arthur I. , Zhang Huatang , Das Gobardhan , Shi Yufang
Published: April 2014

Apoptotic cells induce immunosuppression through unknown mechanisms. To identify the underlying molecular mediators, we examined how apoptotic cells induce immunoregulation by dendritic cells (DC). We found that administration of DC exposed to apoptotic cells (DCap) strongly inhibited the expansion of lymphocytes in draining lymph nodes in vivo and the subsequent Ag-specific activation of these lymphocytes ex vivo. Unexpectedly, DCap supported T cell activation to a similar extent as normal DC in vitro, leading to proliferation and IL-2 production, except that DCap did not support T cell production of IFN-γ. Surprisingly, when DCap were cocultured with normal DC, they completely lost their ability to support T cell activation, an effect reversed by anti-IFN-γ or inhibitors of inducible NO synthase (iNOS). As expected, exposure to apoptotic cells rendered DCap capable of producing much more NO in response to exogenous IFN-γ than normal DC. Furthermore, DCap from iNOS−/− or IFN-γR1−/− mice were not inhibitory in vitro or in vivo. Therefore, the IFN-γ-induced production of NO by apoptotic cell-sensitized DC plays a key role in apoptotic cell-mediated immunosuppression.
Tumor-Induced CD11b+Gr-1+ Myeloid Cells Suppress T Cell Sensitization in Tumor-Draining Lymph Nodes
Authors: Watanabe Satoshi , Deguchi Katsuya , Zheng Rongxiu , Tamai Hidemasa , Wang Li-xin , Cohen Peter A. , Shu Suyu
Published: April 2014

Suppression of tumor-specific T cell sensitization is a predominant mechanism of tumor escape. To identify tumor-induced suppressor cells, we transferred spleen cells from mice bearing progressive MCA205 sarcoma into sublethally irradiated mice. These mice were then inoculated subdermally with tumor cells to stimulate T cell response in the tumor-draining lymph-node (TDLN). Tumor progression induced splenomegaly with a dramatic increase (22.1%) in CD11b+Gr-1+ myeloid-derived suppressor cells (MDSC) compared with 2.6% of that in normal mice. Analyses of therapeutic effects by the adoptive immunotherapy revealed that the transfer of spleen cells from tumor-bearing mice severely inhibited the generation of tumor-immune T cells in the TDLN. We further identified MDSC to be the dominant suppressor cells. However, cells of identical phenotype from normal spleens lacked the suppressive effects. The suppression was independent of CD4+CD25+ regulatory T cells. Intracellular IFN-γ staining revealed that the transfer of MDSC resulted in a decrease in numbers of tumor-specific CD4+ and CD8+ T cells. Transfer of MDSC from MCA207 tumor-bearing mice also suppressed the MCA205 immune response indicating a lack of immunologic specificity. Further analyses demonstrated that MDSC inhibited T cell activation that was triggered either by anti-CD3 mAb or by tumor cells. However, MDSC did not suppress the function of immune T cells in vivo at the effector phase. Our data provide the first evidence that the systemic transfer of MDSC inhibited and interfered with the sensitization of tumor-specific T cell responses in the TDLN.
Transcription Factor-Dependent Chromatin Remodeling of Il18r1 during Th1 and Th2 Differentiation
Authors: Yu Qing , Chang Hua-Chen , Ahyi Ayele-Nati N. , Kaplan Mark H.
Published: April 2014

The IL-18Rα-chain is expressed on Th1 but not Th2 cells. We have recently shown that Stat4 is an important component of programming the Il18r1 locus (encoding IL-18Rα) for maximal expression in Th1 cells. Il18r1 is reciprocally repressed during Th2 development. In this report, we demonstrate the establishment of DH patterns that are distinct among undifferentiated CD4 T, Th1, and Th2 cells. Stat6 is required for the repression of Il18r1 expression and in Stat6-deficient Th2 cultures, mRNA levels, histone acetylation, and H3K4 methylation levels are intermediate between levels observed in Th1 and Th2 cells. Despite the repressive effects of IL-4 during Th2 differentiation, we observed only modest binding of Stat6 to the Il18r1 locus. In contrast, we observed robust GATA-3 binding to a central region of the locus where DNase hypersensitivity sites overlapped with conserved non-coding sequences in Il18r1 introns. Ectopic expression of GATA-3 in differentiated Th1 cells repressed Il18r1 mRNA and surface expression of IL-18Rα. These data provide further mechanistic insight into transcription factor-dependent establishment of Th subset-specific patterns of gene expression.
Statins Induce Regulatory T Cell Recruitment via a CCL1 Dependent Pathway
Authors: Mira Emilia , León Beatriz , Barber Domingo F. , Jiménez-Baranda Sonia , Goya Iñigo , Almonacid Luis , Márquez Gabriel , Zaballos Angel , Martínez-A. Carlos , Stein Jens V. , Ardavín Carlos , Mañes Santos
Published: April 2014

The statins, a group of inhibitors of the 3-hydroxy-3-methylglutaryl coenzyme A reductase, are reported to influence a variety of immune system activities through 3-hydroxy-3-methylglutaryl coenzyme A reductase-dependent and -independent mechanisms. How statin treatment regulates immune system function in vivo nonetheless remains to be fully defined. We analyzed the immunomodulatory effects of lovastatin in a Candida albicans-induced delayed-type hypersensitivity reaction in mice. In this model, lovastatin administration reduced the acute inflammatory response elicited by C. albicans challenge. This anti-inflammatory activity of lovastatin was associated with a shift from a Th1 to a Th2 immune response, as well as an increase in the percentage of regulatory T cells at the inflammation site and in the regional draining lymph node. The lovastatin-induced increase in regulatory T cells in the inflamed skin was dependent on expression of CCL1, a chemokine that is locally up-regulated by statin administration. The anti-inflammatory effect of lovastatin was abrogated in CCL1-deficient mice. These results suggest that local regulation of chemokine expression may be an important process in statin-induced modulation of the immune system.
Splenectomy Protects against Sepsis Lethality and Reduces Serum HMGB1 Levels
Authors: Huston Jared M. , Wang Haichao , Ochani Mahendar , Ochani Kanta , Rosas-Ballina Mauricio , Gallowitsch-Puerta Margot , Ashok Mala , Yang Lihong , Tracey Kevin J. , Yang Huan
Published: April 2014

High mobility group box 1 (HMGB1) is a critical mediator of lethal sepsis. Previously, we showed that apoptotic cells can activate macrophages to release HMGB1. During sepsis, apoptosis occurs primarily in lymphoid organs, including the spleen and thymus. Currently, it is unclear whether this accelerated lymphoid organ apoptosis contributes to systemic release of HMGB1 in sepsis. In this study, we report that splenectomy significantly reduces systemic HMGB1 release and improves survival in mice with polymicrobial sepsis. Treatment with a broad-spectrum caspase inhibitor reduces systemic lymphocyte apoptosis, suppresses circulating HMGB1 concentrations, and improves survival during polymicrobial sepsis, but fails to protect septic mice following splenectomy. These findings indicate that apoptosis in the spleen is essential to the pathogenesis of HMGB1-mediated sepsis lethality.
The Induction of Inflammation by Dectin-1 In Vivo Is Dependent on Myeloid Cell Programming and the Progression of Phagocytosis
Authors: Rosas Marcela , Liddiard Kate , Kimberg Matti , Faro-Trindade Inês , McDonald Jacqueline U. , Williams David L. , Brown Gordon D. , Taylor Philip R.
Published: April 2014

Dectin-1 is the archetypal signaling, non-Toll-like pattern recognition receptor that plays a protective role in immune defense to Candida albicans as the major leukocyte receptor for β-glucans. Dectin-1-deficiency is associated with impaired recruitment of inflammatory leukocytes and inflammatory mediator production at the site of infection. In this study, we have used mice to define the mechanisms that regulate the dectin-1-mediated inflammatory responses. Myeloid cell activation by dectin-1 is controlled by inherent cellular programming, with distinct macrophage and dendritic cell populations responding differentially to the engagement of this receptor. The inflammatory response is further modulated by the progression of the phagocytosis, with “frustrated phagocytosis” resulting in dramatically augmented inflammatory responses. These studies demonstrate that dectin-1 in isolation is sufficient to drive a potent inflammatory response in a context-dependent manner. This has implications for the mechanism by which myeloid cells are activated during fungal infections and the processes involved in the therapeutic manipulation of the immune system via exogenous dectin-1 stimulation or blockade.
Modulation of Lipid and Protein Mediators of Inflammation by Cytosolic Phospholipase A2α during Experimental Sepsis
Authors: Uozumi Naonori , Kita Yoshihiro , Shimizu Takao
Published: April 2014

Cytosolic phospholipase A2α (cPLA2α) is one of the key enzymes in lipid mediator generation. It preferentially hydrolyzes arachidonoyl-phospholipid in response to cellular stimuli, liberating arachidonic acid, the shared precursor of PGs and leukotrienes. Mice with disruption of the cPLA2α gene exhibit a more than 80% decrease in the generation of these lipid mediators, leading to dramatic phenotypes in various models of inflammatory and allergic disease. In this study, we use the cecal ligation and puncture model of sepsis along with multiplex quantitation systems to explore interactions between eicosanoids and protein mediators. cPLA2α-deficient mice exhibited significantly less weight loss accompanied by decreased generation of PGs, leukotriene B4, IL-6, and CCL2. Despite these differences, genetic ablation of cPLA2α did not provide any survival advantage. Unexpectedly, abundant production of 12-hydroxy-eicosatetraenoic acid, another arachidonic acid-derived lipid mediator, was found to be unaffected by disruption of the cPLA2α gene. Eicosanoid production preceded the production of cytokines. Eicosanoid modulation of IL-6 and CCL2 expression was suggested by scattergram analyses. These results provide in vivo evidence for the rapid generation of eicosanoids, regulatory role(s) for cPLA2α-derived lipid mediators on protein mediator production, and the existence of a robust cPLA2α-independent pathway(s) of eicosanoid generation.
Protection of Murine Systemic Lupus by theEaTransgene without Expression of I-E Heterodimers
Authors: Martínez-Soria Eduardo , Santiago-Raber Marie-Laure , Ho Liza , Moll Thomas , Izui Shozo
Published: April 2014

A high-level expression of the Ea transgene encoding the MHC class II I-E α-chain is very effective in the protection from systemic lupus erythematosus (SLE) in mice. However, it has not been elucidated whether this protection results from the induction or increased expression of I-E heterodimers or from the generation of I-E α-chain-derived peptides displaying high affinity for I-A molecules, because previous studies were conducted in lupus-prone mice expressing I-E β-chains. To address this question, we assessed the protective effect of the Ea transgene in lupus-prone BXSB mice bearing the H2q haplotype (i.e., unable to express I-E heterodimers because of a deficiency in I-E β-chains). We observed that the Ea transgene expression resulted in a marked suppression of the development of SLE in H2q BXSB mice despite the absence of I-E expression. The observed protection was not associated with any detectable levels of T cell depletion and regulatory T cell expansion. Significantly, transgenic I-E α-chains were substantially expressed on the surface of B lymphocytes and dendritic cells, but not of macrophages, without apparent formation of mixed-isotype heterodimers with I-A β-chains. Our results demonstrate for the first time that the Ea transgene is able to prevent the development of SLE without induction of I-E heterodimer expression, indicating a critical role of I-E α-chains, but not I-E heterodimers, in the Ea transgene-mediated protection from SLE. Taken together, our data favor a model of autoimmunity prevention based on competition for Ag presentation between I-E α-chain-derived peptides and autoantigens.
PP2A Dephosphorylates Elf-1 and Determines the Expression of CD3ζ and FcRγ in Human Systemic Lupus Erythematosus T Cells
Authors: Juang Yuang-Taung , Wang Ying , Jiang Guisen , Peng Hai-Bin , Ergin Sukran , Finnell Michelle , Magilavy Abigail , Kyttaris Vasileios C. , Tsokos George C.
Published: April 2014

T cells from patients with systemic lupus erythematosus are characterized by decreased expression of CD3ζ-chain and increased expression of FcRγ-chain, which becomes part of the CD3 complex and contributes to aberrant signaling. Elf-1 enhances the expression of CD3ζ, whereas it suppresses the expression of FcRγ gene and lupus T cells have decreased amounts of DNA-binding 98 kDa form of Elf-1. We show that the aberrantly increased PP2A in lupus T cells dephosphorylates Elf-1 at Thr-231. Dephosphorylation results in limited expression and binding of the 98 kDa Elf-1 form to the CD3ζ and FcRγ promoters. Suppression of the expression of the PP2A leads to increased expression of CD3ζ and decreased expression of FcRγ genes and correction of the early signaling response. Therefore, PP2A serves as a central determinant of abnormal T cell function in human lupus and may represent an appropriate treatment target.
Cutting Edge: Th1 Cells Facilitate the Entry of Th17 Cells to the Central Nervous System during Experimental Autoimmune Encephalomyelitis
Authors: O'Connor Richard A. , Prendergast Catriona T. , Sabatos Catherine A. , Lau Clement W. Z. , Leech Melanie D. , Wraith David C. , Anderton Stephen M.
Published: April 2014

It has recently been proposed that experimental autoimmune encephalomyelitis, once considered the classical Th1 disease, is predominantly Th17 driven. In this study we show that myelin-reactive Th1 preparations devoid of contaminating IL-17+ cells are highly pathogenic. In contrast, Th17 preparations lacking IFN-γ+ cells do not cause disease. Our key observation is that only Th1 cells can access the noninflamed CNS. Once Th1 cells establish the experimental autoimmune encephalomyelitis lesion, Th17 cells appear in the CNS. These data shed important new light on the ability of Th1 vs Th17 cells to access inflamed vs normal tissue. Because the IL-17-triggered release of chemokines by stromal cells could attract many other immune cells, allowing Th17 cells to access the tissues only under conditions of inflammation may be a key process limiting (auto)immune pathology. This has major implications for the design of therapeutic interventions, many of which are now aiming at Th17 rather than Th1 cells.
IL-12Rβ2 Promotes the Development of CD4+CD25+ Regulatory T Cells
Authors: Zhao Zhao , Yu Shuo , Fitzgerald Denise C. , Elbehi Mohamed , Ciric Bogoljub , Rostami A. M. , Zhang Guang-Xian
Published: April 2014

We have previously shown that mice lacking the IL-12-specific receptor subunit β2 (IL-12Rβ2) develop more severe experimental autoimmune encephalomyelitis than wild-type (WT) mice. The mechanism underlying this phenomenon is not known; nor is it known whether deficiency of IL-12Rβ2 impacts other autoimmune disorders similarly. In the present study we demonstrate that IL-12Rβ2−/− mice develop earlier onset and more severe disease in the streptozotocin-induced model of diabetes, indicating predisposition of IL-12Rβ2-deficient mice to autoimmune diseases. T cells from IL-12Rβ2−/− mice exhibited significantly higher proliferative responses upon TCR stimulation. The numbers of naturally occurring CD25+CD4+ regulatory T cells (Tregs) in the thymus and spleen of IL-12Rβ2−/− mice were comparable to those of WT mice. However, IL-12Rβ2−/− mice exhibited a significantly reduced capacity to develop Tregs upon stimulation with TGF-β, as shown by significantly lower numbers of CD25+CD4+ T cells that expressed Foxp3. Functionally, CD25+CD4+ Tregs derived from IL-12Rβ2−/− mice were less efficient than those from WT mice in suppressing effector T cells. The role of IL-12Rβ2 in the induction of Tregs was confirmed using small interfering RNA. These findings suggest that signaling via IL-12Rβ2 regulates both the number and functional maturity of Treg cells, which indicates a novel mechanism underlying the regulation of autoimmune diseases by the IL-12 pathway.
CD137 Induces Proliferation of Murine Hematopoietic Progenitor Cells and Differentiation to Macrophages
Authors: Jiang Dongsheng , Chen Yifeng , Schwarz Herbert
Published: April 2014

CD137 is a member of the TNFR family, and reverse signaling through the CD137 ligand, which is expressed as a cell surface transmembrane protein, costimulates or activates APCs. CD137 and CD137 ligand are expressed on small subsets of bone marrow cells. Activation of bone marrow cells through CD137 ligand induces proliferation, colony formation and an increase in cell numbers. Compared with total bone marrow cells, the small subpopulation of progenitor cells that express no lineage markers but express CD117 cells (or Lin−, CD117+ cells) responds with the same activities to CD137 ligand signaling, but at a significantly enhanced rate. Concomitantly to proliferation, the cells differentiate to CFU granulocyte-macrophage and CFU macrophage, and then to monocytes and macrophages but not to granulocytes or dendritic cells. Hematopoietic progenitor cells differentiated in the presence of CD137 protein display enhanced phagocytic activity, secrete high levels of IL-10 but little IL-12 in response to LPS, and are incapable of stimulating T cell proliferation. These data demonstrate that reverse CD137 ligand signaling takes place in hematopoietic progenitor cells, in which it induces proliferation, an increase in cell numbers, colony formation, and differentiation toward monocytes and macrophages.
Editing Antigen Presentation: Antigen Transfer between Human B Lymphocytes and Macrophages Mediated by Class A Scavenger Receptors
Authors: Harvey Bohdan P. , Quan Timothy E. , Rudenga Benjamin J. , Roman Robert M. , Craft Joe , Mamula Mark J.
Published: April 2014

B lymphocytes can function independently as efficient APCs. However, our previous studies demonstrate that both dendritic cells and macrophages are necessary to propagate immune responses initiated by B cell APCs. This finding led us to identify a process in mice whereby Ag-specific B cells transfer Ag to other APCs. In this study, we report the ability and mechanism by which human B lymphocytes can transfer BCR-captured Ag to macrophages. The transfer of Ag involves direct contact between the two cells followed by the capture of B cell-derived membrane and/or intracellular components by the macrophage. These events are abrogated by blocking scavenger receptor A, a receptor involved in the exchange of membrane between APCs. Macrophages acquire greater amounts of Ag in the presence of specific B cells than in their absence. This mechanism allows B cells to amplify or edit the immune response to specific Ag by transferring BCR-captured Ag to other professional APCs, thereby increasing the frequency of its presentation. Ag transfer may perpetuate chronic autoimmune responses to specific self-proteins and help explain the efficacy of B cell-directed therapies in human disease.
Smallpox Inhibitor of Complement Enzymes (SPICE): Regulation of Complement Activation on Cells and Mechanism of Its Cellular Attachment
Authors: Liszewski M. Kathryn , Bertram Paula , Leung Marilyn K. , Hauhart Richard , Zhang Lijuan , Atkinson John P.
Published: April 2014

Despite eradication of smallpox three decades ago, public health concerns remain due to its potential use as a bioterrorist weapon. Smallpox and other orthopoxviruses express virulence factors that inhibit the host’s complement system. In this study, our goals were to characterize the ability of the smallpox inhibitor of complement enzymes, SPICE, to regulate human complement on the cell surface. We demonstrate that SPICE binds to a variety of cell types and that the heparan sulfate and chondroitin sulfate glycosaminoglycans serve as attachment sites. A transmembrane-engineered version as well as soluble recombinant SPICE inhibited complement activation at the C3 convertase step with equal or greater efficiency than that of the related host regulators. Moreover, SPICE attached to glycosaminoglycans was more efficient than transmembrane SPICE. We also demonstrate that this virulence activity of SPICE on cells could be blocked by a mAb to SPICE. These results provide insights related to the complement inhibitory activities of poxviral inhibitors of complement and describe a mAb with therapeutic potential.
High Mobility Group Protein-1 Inhibits Phagocytosis of Apoptotic Neutrophils through Binding to Phosphatidylserine
Authors: Liu Gang , Wang Jing , Park Young-Jun , Tsuruta Yuko , Lorne Emmanuel F. , Zhao Xia , Abraham Edward
Published: April 2014

Phagocytosis of apoptotic cells, also called efferocytosis, is an essential feature of immune responses and critical to resolution of inflammation. Impaired efferocytosis is associated with an unfavorable outcome from inflammatory diseases, including acute lung injury and pulmonary manifestations of cystic fibrosis. High mobility group protein-1 (HMGB1), a nuclear nonhistone DNA-binding protein, has recently been found to be secreted by immune cells upon stimulation with LPS and cytokines. Plasma and tissue levels of HMGB1 are elevated for prolonged periods in chronic and acute inflammatory conditions, including sepsis, rheumatoid arthritis, acute lung injury, burns, and hemorrhage. In this study, we found that HMGB1 inhibits phagocytosis of apoptotic neutrophils by macrophages in vivo and in vitro. Phosphatidylserine (PS) is directly involved in the inhibition of phagocytosis by HMGB1, as blockade of HMGB1 by PS eliminates the effects of HMGB1 on efferocytosis. Confocal and fluorescence resonance energy transfer demonstrate that HMGB1 interacts with PS on the neutrophil surface. However, HMGB1 does not inhibit PS-independent phagocytosis of viable neutrophils. Bronchoalveolar lavage fluid from Scnn+ mice, a murine model of cystic fibrosis lung disease which contains elevated concentrations of HMGB1, inhibits neutrophil efferocytosis. Anti-HMGB1 Abs reverse the inhibitory effect of Scnn+ bronchoalveolar lavage on efferocytosis, showing that this effect is due to HMGB1. These findings demonstrate that HMGB1 can modulate phagocytosis of apoptotic neutrophils and suggest an alternative mechanism by which HMGB1 is involved in enhancing inflammatory responses.
Inhibition of Arginase Activity Enhances Inflammation in Mice with Allergic Airway Disease, in Association with Increases in Protein S-Nitrosylation and Tyrosine Nitration
Authors: Ckless Karina , Lampert Anniek , Reiss Jessica , Kasahara David , Poynter Matthew E. , Irvin Charles G. , Lundblad Lennart K. A. , Norton Ryan , van der Vliet Albert , Janssen-Heininger Yvonne M. W.
Published: April 2014

Pulmonary inflammation in asthma is orchestrated by the activity of NF-κB. NO and NO synthase (NOS) activity are important modulators of inflammation. The availability of the NOS substrate, l-arginine, is one of the mechanisms that controls the activity of NOS. Arginase also uses l-arginine as its substrate, and arginase-1 expression is highly induced in a murine model of asthma. Because we have previously described that arginase affects NOx content and interferes with the activation of NF-κB in lung epithelial cells, the goal of this study was to investigate the impact of arginase inhibition on the bioavailability of NO and the implications for NF-κB activation and inflammation in a mouse model of allergic airway disease. Administration of the arginase inhibitor BEC (S-(2-boronoethyl)-l-cysteine) decreased arginase activity and caused alterations in NO homeostasis, which were reflected by increases in S-nitrosylated and nitrated proteins in the lungs from inflamed mice. In contrast to our expectations, BEC enhanced perivascular and peribronchiolar lung inflammation, mucus metaplasia, NF-κB DNA binding, and mRNA expression of the NF-κB-driven chemokine genes CCL20 and KC, and lead to further increases in airways hyperresponsiveness. These results suggest that inhibition of arginase activity enhanced a variety of parameters relevant to allergic airways disease, possibly by altering NO homeostasis.
Unique Properties of the Chicken TLR4/MD-2 Complex: Selective Lipopolysaccharide Activation of the MyD88-Dependent Pathway
Authors: Keestra A. Marijke , van Putten Jos P. M.
Published: April 2014

During evolution, mammals have evolved a powerful innate immune response to LPS. Chickens are much more resistant to LPS-induced septic shock. Herein we report that chickens sense LPS via orthologs of mammalian TLR4 and myeloid differentiation protein-2 (MD-2) rather than the previously implicated chicken TLR2 isoform type 2 (chTLR2t2) receptor. Cloning and expression of recombinant chTLR4 and chMD-2 in HeLa 57A cells activated NF-κB at concentrations of LPS as low as 100 pg/ml. Differential pairing of chicken and mammalian TLR4 and MD-2 indicated that the protein interaction was species-specific in contrast to the formation of functional human and murine chimeric complexes. The chicken LPS receptor responded to a wide variety of LPS derivatives and to the synthetic lipid A compounds 406 and 506. The LPS specificity resembled the functionality of the murine rather than the human TLR4/MD-2 complex. Polymorphism in chTLR4 (Tyr383His and Gln611Arg) did not influence the LPS response. Interestingly, LPS consistently failed to activate the MyD88-independent induction of IFN-β in chicken cells, in contrast to the TLR3 agonist poly(I:C) that yielded a potent IFN-β response. These results suggest that chicken lack a functional LPS-specific TRAM-TRIF (TRIF-related adapter molecule/TIR-domain-containing adapter-inducing IFN-β) signaling pathway, which may explain their aberrant response to LPS compared with the mammalian species.
4-1BB Enhances Proliferation of Beryllium-Specific T Cells in the Lung of Subjects with Chronic Beryllium Disease
Authors: Mack Douglas G. , Lanham Allison K. , Palmer Brent E. , Maier Lisa A. , Watts Tania H. , Fontenot Andrew P.
Published: April 2014

In contrast to naive T cells, reactivation of memory cells is less dependent on CD28-mediated costimulation. We have shown that circulating beryllium-specific CD4+ T cells from chronic beryllium disease patients remain CD28-dependent, while those present in the lung no longer require CD28 for T cell activation. In the present study, we analyzed whether other costimulatory molecules are essential for beryllium-induced T cell function in the lung. Enhanced proliferation of a beryllium-responsive, HLA-DP2-restricted T cell line was seen after the induction of 4-1BB ligand expression on the surface of HLA-DP2-expressing fibroblasts. Following beryllium exposure, CD4+ T cells from blood and bronchoalveolar lavage of chronic beryllium disease patients up-regulate 4-1BB expression, and the majority of beryllium-responsive, IFN-γ-producing CD4+ T cells in blood coexpress CD28 and 4-1BB. Conversely, a significant fraction of IFN-γ-producing bronchoalveolar lavage (BAL) T cells express 4-1BB in the absence of CD28. In contrast to blood, inhibition of the 4-1BB ligand-4-1BB interaction partially blocked beryllium-induced proliferation of BAL CD4+ T cells, and a lack of 4-1BB expression on BAL T cells was associated with increased beryllium-induced cell death. Taken together, these findings suggest an important role of 4-1BB in the costimulation of beryllium-responsive CD4+ T cells in the target organ.
Cutting Edge: The Mechanism of Invariant NKT Cell Responses to Viral Danger Signals
Authors: Tyznik Aaron J. , Tupin Emmanuel , Nagarajan Niranjana A. , Her Min J. , Benedict Chris A. , Kronenberg Mitchell
Published: April 2014

Invariant NK T (iNKT) cells influence the response to viral infections, although the mechanisms are poorly defined. In this study we show that these innate-like lymphocytes secrete IFN-γ upon culture with CpG oligodeoxynucleotide-stimulated dendritic cells (DCs) from mouse bone marrow. This requires TLR9 signaling and IL-12 secretion by the activated DCs, but it does not require CD1d expression. iNKT cells also produce IFN-γ in response to mouse CMV infection. Their mechanism of mouse CMV detection is quite similar to that of CpG, requiring both TLR9 signaling and IL-12 secretion, while the need for CD1d expression is relatively minor. Consequently, iNKT cells have the ability to respond to a variety of microbes, including viruses, in an Ag-independent manner, suggesting they may play a broad role in antipathogen defenses despite their limited TCR repertoire.
IFN-γ-Induced TNF-α Expression Is Regulated by Interferon Regulatory Factors 1 and 8 in Mouse Macrophages
Authors: Vila-del Sol Virginia , Punzón Carmen , Fresno Manuel
Published: April 2014

We have previously described that IFN-γ induces cyclooxygenase 2 and inducible NO synthase expression by a mechanism that involved endogenously produced TNF-α. In this study, we report that TNF-α production is induced by IFN-γ treatment in the murine macrophage cell line RAW 264.7. TNF-α mRNA levels are increased in cells treated with IFN-γ in a time-dependent manner and IFN-γ also increased human TNF-α promoter-dependent transcription. Two regions in the TNF-α promoter seem to be responsible for the IFN-γ response: a distal region between −1311 and −615 bp of the human TNF-α promoter, and a proximal region located between −95 and −36 bp upstream of the transcriptional start. In contrast, IFN-γ stimulation induces the expression of the transcription factors IRF-1 and IRF-8. Overexpression of these transcription factors produces an increase in the transcriptional activity of the human TNF-α promoter. There is a correlation between the regions of the TNF-α promoter responsible of the transcriptional activation elicited by IRF-1 and IRF-8 and those required for IFN-γ response. In addition, IRF-1 and IRF-8 are recruited to the TNF-α promoter in IFN-γ-treated RAW 264.7 cells, as demonstrated by chromatin immunoprecipitation assays. Moreover, overexpression of IRF-1 and IRF-8 induces TNF-α production in unstimulated RAW 264.7 macrophages, comparable to the production of TNF-α elicited by IFN-γ stimulation, and silencing of IRF-1 and/or IRF-8 with specific small interfering RNAs, decreases IFN-γ-elicited TNF-α production. In summary, IFN-γ treatment induces TNF-α expression at transcriptional level requiring the coordinate action of IRF-1 and IRF-8.
Activation of Nonclassical CD1d-Restricted NK T Cells Induces Airway Hyperreactivity in β2-Microglobulin-Deficient Mice
Authors: Koh Youngil I. , Kim Hye Young , Meyer Everett H. , Pichavant Muriel , Akbari Omid , Yasumi Takahiro , Savage Paul B. , DeKruyff Rosemarie H. , Umetsu Dale T.
Published: April 2014

Allergic asthma is characterized by Th2-driven eosinophilic airway inflammation and by a central feature called airway hyperreactivity (AHR), development of which requires the presence of classical type I invariant NK T (iNKT) cells. Allergen-induced AHR, however, develops in β2-microglobulin (β2m)−/− mice, which lack classical iNKT cells, suggesting that in some situations iNKT cells may be dispensable for the development of AHR. In contrast, our studies now suggest that a CD1d-restricted, NK1.1+ noninvariant TCR NKT cell population is present in β2m−/− mice and is responsible for the development of AHR but not for Th2 responses. Furthermore, treatment of β2m−/− mice with anti-CD1d mAb or anti-NK1.1 mAb unexpectedly abolished allergen-induced AHR. The CD1-restricted NKT cells in these mice, which failed to respond to α-galactosylceramide and which therefore were not classical type I iNKT cells, appear to represent an NKT cell subset restricted by a β2m-independent form of CD1d. These results indicate that, although classical type I iNKT cells are normally required for the development of AHR, under different circumstances other NKT cell subsets, including nonclassical NKT cells, may substitute for classical iNKT cells and induce AHR.
Galectin-1 Promotes Immunoglobulin Production during Plasma Cell Differentiation
Authors: Tsai Chih-Ming , Chiu Yi-Kai , Hsu Tsui-Ling , Lin I-Ying , Hsieh Shie-Liang , Lin Kuo-I
Published: April 2014

Galectin-1, a β-galactoside-binding soluble lectin, has been implicated in regulating immune system homeostasis. We investigated the function of galectin-1 in plasma cell differentiation and found that it is induced in primary murine and human differentiating B cells. B lymphocyte-induced maturation protein-1 (Blimp-1), a master regulator for plasma cell differentiation, was necessary and sufficient to induce galectin-1 expression. Notably, ectopic expression of galectin-1 in mature B cells increased Ig μ-chain transcript levels as well as the overall level of Ig production. This function of galectin-1 was dependent on binding to cell surface glycosylated counter receptors, as a galectin-1 mutant deficient in β-galactoside binding showed diminished ability to promote Ig production. Extracellular galectin-1 bound more significantly to mature B cells than to plasma cells. Lastly, we found that the sugar compound N-acetyllactosamine blocked the binding of galectin-1 to murine splenic B cells and inhibited their differentiation. Taken together, these data are the first to demonstrate a role for galectin-1 in promoting Ig production during plasma cell differentiation.
Nicotinamide Phosphoribosyl Transferase/Pre-B Cell Colony-Enhancing Factor/Visfatin Is Required for Lymphocyte Development and Cellular Resistance to Genotoxic Stress
Authors: Rongvaux Anthony , Galli Mara , Denanglaire Sébastien , Van Gool Frédéric , Drèze Pierre L. , Szpirer Claude , Bureau Fabrice , Andris Fabienne , Leo Oberdan
Published: April 2014

Nicotinamide phosphoribosyl transferase (Nampt)/pre-B cell colony-enhancing factor (PBEF)/visfatin is a protein displaying multiple functional properties. Originally described as a cytokine-like protein able to regulate B cell development, apoptosis, and glucose metabolism, this protein also plays an important role in NAD biosynthesis. To gain insight into its physiological role, we have generated a mouse strain expressing a conditional Nampt allele. Lack of Nampt expression strongly affects development of both T and B lymphocytes. Analysis of hemizygous cells and in vitro cell lines expressing distinct levels of Nampt illustrates the critical role of this protein in regulating intracellular NAD levels. Consequently, a clear relationship was found between intracellular Nampt levels and cell death in response to the genotoxic agent MNNG (N-methyl-N′-nitro-N-nitrosoguanidine), confirming that this enzyme represents a key regulator of cell sensitivity to NAD-consuming stress secondary to poly(ADP-ribose) polymerases overactivation. By using mutant forms of this protein and a well-characterized pharmacological inhibitor (FK866), we unequivocally demonstrate that the ability of the Nampt to regulate cell viability during genotoxic stress requires its enzymatic activity. Collectively, these data demonstrate that Nampt participates in cellular resistance to genotoxic/oxidative stress, and it may confer to cells of the immune system the ability to survive during stressful situations such as inflammation.
Inhibitory Immunoglobulin-Like Receptors LILRB and PIR-B Negatively Regulate Osteoclast Development
Authors: Mori Yu , Tsuji Sukenao , Inui Masanori , Sakamoto Yuzuru , Endo Shota , Ito Yumi , Fujimura Shion , Koga Takako , Nakamura Akira , Takayanagi Hiroshi , Itoi Eiji , Takai Toshiyuki
Published: April 2014

Osteoclasts, multinucleated cells of myeloid-monocytic origin, are responsible for bone resorption, which is crucial for maintenance of bone homeostasis in concert with bone-forming osteoblasts of nonhematopoietic, mesenchymal origin. Receptor activator of NF-κB ligand (RANKL) and M-CSF, expressed on the surface of and secreted by osteoblasts, respectively, are essential factors that facilitate osteoclast formation. In contrast to the activation processes for osteoclast formation, inhibitory mechanisms for it are poorly understood. Herein we demonstrate that inhibitory Ig-like receptors recruiting Src homology 2 domain-containing tyrosine phosphatase 1 (SHP-1) are expressed on osteoclast precursor cells like other myeloid cells, and that they play a regulatory role in the development of osteoclasts. We detected cell-surface expression of paired Ig-like receptor (PIR)-B and four isoforms of leukocyte Ig-like receptor (LILR)B on cultured osteoclast precursor cells of mouse and human origin, respectively, and showed that all of these ITIM-harboring inhibitory receptors constitutively recruit SHP-1 in the presence of RANKL and M-CSF, and that some of them can suppress osteoclast development in vitro. Fluorescence energy transfer analyses have suggested that the constitutive binding of either murine PIR-B or its human ortholog LILRB1 to MHC class I molecules on the same cell surface comprises one of the mechanisms for developmental regulation. These results constitute the first evidence of the regulation of osteoclast formation by cell-surface, ITIM-harboring Ig-like receptors. Modulation of these regulatory receptors may be a novel way to control various skeletal system disorders and inflammatory arthritis.
Vaccination-Induced Systemic Autoimmunity in Farmed Atlantic Salmon
Authors: Koppang Erling O. , Bjerkås Inge , Haugarvoll Erlend , Chan Edward K. L. , Szabo Nancy J. , Ono Nobutaka , Akikusa Bunshiro , Jirillo Emilio , Poppe Trygve T. , Sveier Harald , Tørud Brit , Satoh Minoru
Published: April 2014

Over half of the salmon consumed globally are farm-raised. The introduction of oil-adjuvanted vaccines into salmon aquaculture made large-scale production feasible by preventing infections. The vaccines that are given i.p. contain oil adjuvant such as mineral oil. However, in rodents, a single i.p. injection of adjuvant hydrocarbon oil induces lupus-like systemic autoimmune syndrome, characterized by autoantibodies, immune complex glomerulonephritis, and arthritis. In the present study, whether the farmed salmon that received oil-adjuvanted vaccine have autoimmune syndrome similar to adjuvant oil-injected rodents was examined. Sera and tissues were collected from vaccinated or unvaccinated Atlantic salmon (experimental, seven farms) and wild salmon. Autoantibodies (immunofluorescence, ELISA, and immunoprecipitation) and IgM levels (ELISA) in sera were measured. Kidneys and livers were examined for pathology. Autoantibodies were common in vaccinated fish vs unvaccinated controls and they reacted with salmon cells/Ags in addition to their reactivity with mammalian Ags. Diffuse nuclear/cytoplasmic staining was common in immunofluorescence but some had more specific patterns. Serum total IgM levels were also increased in vaccinated fish; however, the fold increase of autoantibodies was much more than that of total IgM. Sera from vaccinated fish immunoprecipitated ferritin and ∼50% also reacted with other unique proteins. Thrombosis and granulomatous inflammation in liver, and immune-complex glomerulonephritis were common in vaccinated fish. Autoimmunity similar to the mouse model of adjuvant oil-induced lupus is common in vaccinated farmed Atlantic salmon. This may have a significant impact on production loss, disease of previously unknown etiology, and future strategies of vaccines and salmon farming.
Protein Kinase Cθ Regulates Stability of the Peripheral Adhesion Ring Junction and Contributes to the Sensitivity of Target Cell Lysis by CTL
Authors: Beal Allison M. , Anikeeva Nadia , Varma Rajat , Cameron Thomas O. , Norris Philip J. , Dustin Michael L. , Sykulev Yuri
Published: April 2014

Destruction of virus-infected cells by CTL is an extremely sensitive and efficient process. Our previous data suggest that LFA-1-ICAM-1 interactions in the peripheral supramolecular activation cluster (pSMAC) of the immunological synapse mediate formation of a tight adhesion junction that might contribute to the sensitivity of target cell lysis by CTL. Herein, we compared more (CD8+) and less (CD4+) effective CTL to understand the molecular events that promote efficient target cell lysis. We found that abrogation of the pSMAC formation significantly impaired the ability of CD8+ but not CD4+ CTL to lyse target cells despite having no effect of the amount of released granules by both CD8+ and CD4+ CTL. Consistent with this, CD4+ CTL break their synapses more often than do CD8+ CTL, which leads to the escape of the cytolytic molecules from the interface. CD4+ CTL treatment with a protein kinase Cθ inhibitor increases synapse stability and sensitivity of specific target cell lysis. Thus, formation of a stable pSMAC, which is partially controlled by protein kinase Cθ, functions to confine the released lytic molecules at the synaptic interface and to enhance the effectiveness of target cell lysis.
Neutrophil Elastase Mediates Innate Host Protection against Pseudomonas aeruginosa
Authors: Hirche Tim O. , Benabid Rym , Deslee Gaetan , Gangloff Sophie , Achilefu Samuel , Guenounou Moncef , Lebargy François , Hancock Robert E. , Belaaouaj Azzaq
Published: April 2014

According to the widely accepted view, neutrophil elastase (NE), a neutrophil-specific serine protease, is a major contributor to Pseudomonas aeruginosa infection-associated host tissue inflammation and damage, which in severe cases can lead to death. Herein, we provide for the first time compelling evidence that the host rather employs NE to protect itself against P. aeruginosa infection. Using a clinically relevant model of pneumonia, targeted deficiency in NE increased the susceptibility of mice to P. aeruginosa. We found that NE was required for maximal intracellular killing of P. aeruginosa by neutrophils. In investigating the mechanism of NE-mediated killing of P. aeruginosa, we found that NE degraded the major outer membrane protein F, a protein with important functions, including porin activity, maintenance of structural integrity, and sensing of host immune system activation. Consistent with this, the use of an isogenic mutant deficient in outer membrane protein F negated the role of NE in host defense against P. aeruginosa infection.