bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective Inhibition of Inducible NO Synthase Activity In Vivo Reverses Inflammatory Abnormalities in Surfactant Protein D-Deficient Mice
Authors: Atochina-Vasserman Elena N. , Beers Michael F. , Kadire Helchem , Tomer Yaniv , Inch Adam , Scott Pamela , Guo Chang J. , Gow Andrew J.
Published: April 2014

Surfactant protein D (SP-D)-deficient (SP-D−/−) mice exhibit early development of emphysema. Previously we have shown that SP-D deficiency results in increased production and activity of inducible NO synthase (iNOS). In this study, we examined whether treatment with the iNOS inhibitor 1400W could inhibit the inflammatory phenotype. Mice were treated with 1400W systemically for 7 wk from 3 wk of age. Treatment reduced total lung NO synthase activity to 14.7 ± 6.1% of saline-treated 10-wk-old SP-D−/− littermates. Long-term administration of 1400W reduced lung inflammation and cellular infiltration; and significantly attenuated the increased levels of matrix metalloproteinases 2 and 9, chemokines (KC, TARC), and cytokines (IFN-γ) seen in bronchoalveolar lavage (BAL) of SP-D−/− mice. Abrogation of these levels was associated with decreasing BAL chemotactic activity for RAW cells. Two weeks of treatment with 1400W reduced total lung NO synthase (NOS) activity to 12.7 ± 6.3% of saline-treated SP-D−/− mice. Short-term iNOS inhibition resulted in attenuation of pulmonary inflammation within SP-D−/− mice as shown by decreases in total BAL cell count (63 ± 6% of SP-D−/− control), macrophage size (>25 μm) within the BAL (62 ± 10% of SP-D−/− control), and a percentage of BAL macrophages producing oxidants (76 ± 9% of SP-D−/− control). These studies showed that s.c. delivery of 1400W can be achieved in vivo and can attenuate the inflammatory processes within SP-D deficiency. Our results represent the first report linking defects in the innate immune system in the lung with alterations in NO homeostasis.
Introduction of Zwitterionic Motifs into Bacterial Polysaccharides Generates TLR2 Agonists Able to Activate APCs
Authors: Gallorini Simona , Berti Francesco , Parente Pierino , Baronio Roberta , Aprea Susanna , D’Oro Ugo , Pizza Mariagrazia , Telford John L. , Wack Andreas
Published: April 2014

It was shown previously that bacterial polysaccharides (PS), which naturally contain both positive and negative charges, are able to activate T cells and APCs. However, the vast majority of bacterial PS are anionic and do not have these properties. In this study, we show that chemical introduction of positive charges into naturally anionic bacterial PS confers to the resulting zwitterionic PS (ZPS) the ability to activate pure human monocytes, monocyte-derived dendritic cells, and mouse bone marrow-derived dendritic cells, as do natural bacterial ZPS. Cells are induced to up-regulate MHC class II and costimulatory molecules and to produce cytokines. In mixed monocyte-T cell cocultures, ZPS induce MHC II-dependent T cell proliferation and up-regulation of activation markers. These stimulatory qualities of ZPS disappear when the positive charge is chemically removed from the molecules and thus the zwitterionic motif is destroyed. The ability of natural and chemically derived ZPS to activate APCs can be blocked by anti-TLR2 mAbs, and TLR2 transfectants show reporter gene transcription upon incubation with ZPS. In conclusion, the generation of a zwitterionic motif in bacterial PS confers the ability to activate both APCs and T cells. This finding has important implications for the design of novel polysaccharide vaccines.
Interaction between GATA-3 and the Transcriptional Coregulator Pias1 Is Important for the Regulation of Th2 Immune Responses
Authors: Zhao Xinyan , Zheng Bo , Huang Yanfang , Yang Dan , Katzman Shoshana , Chang Chawnshang , Fowell Deborah , Zeng Wei-ping
Published: April 2014

Th2 cytokine expression is dependent on the transcription factor GATA-3. However, the molecular interactions of GATA-3 leading to Th2 cytokine gene activation have not been well characterized. Here, we reported a number of GATA-3 associated proteins in Th2 cells, and one of such proteins Pias1 functioned as a positive transcriptional coregulator for GATA-3. When overexpressed in Th2 cells, Pias1 enhanced the expression of IL-13, and to lesser degrees, IL-4 and -5. Conversely, Pias1 siRNA down-regulated the Th2 cytokine expression. In Leishmania major infection, manipulating Pias1 expression in parasite-reactive CD4 T cells altered severity of disease caused by Th2 responses. Mechanistically, Pias1 markedly potentiated GATA-3-mediated activation of the IL-13 promoter by facilitating the recruitment of GATA-3 to the promoter. In contrast, IL-5 promoter was modestly enhanced by Pias1 and no effect was observed on IL-4 promoter. Thus, both promoter activation and additional mechanisms are responsible for regulation by Pias1.
An Effect of Parasite-Encoded Arginase on the Outcome of Murine Cutaneous Leishmaniasis
Authors: Gaur Upasna , Roberts Sigrid C. , Dalvi Rahul P. , Corraliza Inés , Ullman Buddy , Wilson Mary E.
Published: April 2014

Classical activation of macrophages infected with Leishmania species results in expression and activation of inducible NO synthase (iNOS) leading to intracellular parasite killing. Macrophages can contrastingly undergo alternative activation with increased arginase activity, metabolism of arginine along the polyamine pathway, and consequent parasite survival. An active role for parasite-encoded arginase in host microbicidal responses has not previously been documented. To test the hypothesis that parasite-encoded arginase can influence macrophage responses to intracellular Leishmania, a comparative genetic approach featuring arginase-deficient mutants of L. mexicana lacking both alleles of the gene encoding arginase (Δarg), as well as wild-type and complemented Δarg controls (Δarg[pArg]), was implemented. The studies showed: 1) the absence of parasite arginase resulted in a significantly attenuated infection of mice (p < 0.05); 2) poorer survival of Δarg in mouse macrophages than controls correlated with greater NO generation; 3) the difference between Δarg or control intracellular survival was abrogated in iNOS-deficient macrophages, suggesting iNOS activity was responsible for increased Δarg killing; 4) consistently, immunohistochemistry showed enhanced nitrotyrosine modifications in tissues of mice infected with Δarg compared with control parasites. Furthermore, 5) in the face of decreased parasite survival, lymph node cells draining cutaneous lesions of Δarg parasites produced more IFN-γ and less IL-4 and IL-10 than controls. These data intimate that parasite-encoded arginase of Leishmania mexicana subverts macrophage microbicidal activity by diverting arginine away from iNOS.
Gads−/− Mice Reveal Functionally Distinct Subsets of TCRβ+ CD4−CD8− Double-Negative Thymocytes
Authors: Zeng Ling , Dalheimer Stacy L. , Yankee Thomas M.
Published: April 2014

TCRβ expression in CD4−CD8− double-negative (DN) thymocytes induces signaling pathways that promote survival and proliferation, as well as differentiation into CD4+CD8+ double-positive thymocytes. The signaling pathways that regulate survival, proliferation, and differentiation remain unclear. We used Gads-deficient mice to investigate the signaling pathways that regulate these cell fates. During this investigation, we focused on TCRβ+ DN thymocytes and found that there are at least three functionally distinct subsets of TCRβ+ DN thymocytes: TCRβ+ DN3E, TCRβ+ DN3L, and TCRβ+ DN4. Survival and proliferation of TCRβ+ DN3E were independent of Gads, but survival and proliferation of TCRβ+ DN3L cells were Gads dependent. Likewise, expression of Bcl-2 in TCRβ+ DN3E cells was Gads independent, but Gads was necessary for Bcl-2 expression in TCRβ+ DN3L cells. Bcl-2 expression was not dependent on Gads in TCRβ+ DN4 cells, but proliferation of TCRβ+ DN4 cells was Gads dependent. Gads was not required for the differentiation of DN thymocytes into DP thymocytes. In fact, Gads−/− DN3E cells differentiated into DP thymocytes more readily than wild-type cells. We conclude that signaling pathways required to initiate TCRβ-induced survival and proliferation are distinct from the pathways that maintain survival and proliferation. Furthermore, signaling pathways that promote survival and proliferation may slow differentiation.
Parallel Expansion of Human Virus-Specific FoxP3− Effector Memory and De Novo-Generated FoxP3+ Regulatory CD8+ T Cells upon Antigen Recognition In Vitro
Authors: Billerbeck Eva , Blum Hubert E. , Thimme Robert
Published: April 2014

Although FoxP3 has been shown to be the most specific marker for regulatory CD4+ T cells, its significance in the CD8+ T cell population is not well understood. In this study, we show that the in vitro stimulation of human PBMC with hepatitis C virus or Flu virus-specific peptides gives rise to two distinct Ag-specific T cell populations: FoxP3− and FoxP3+CD8+ T cells. The FoxP3+ virus-specific CD8+ T cells share phenotypical markers of regulatory T cells, such as CTLA-4 and glucocorticoid-induced TNFR family-related gene, and do produce moderate amounts of IFN-γ but not IL-2 or IL-10. IL-2 and IL-10 are critical cytokines, however, because the expansion of virus-specific FoxP3+CD8+ T cells is blocked by IL-2- or IL-10-neutralizing mAbs. The virus-specific FoxP3+CD8+ T cells have a reduced proliferative capacity, indicating anergy, and display a cell-cell contact-dependent suppressive activity. Taken together, our results indicate that stimulation with a defined viral Ag leads to the expansion of two different cell populations: FoxP3− memory/effector as well as FoxP3+ regulatory virus-specific CD8+ T cells.
Ig Allotypic Inclusion Does Not Prevent B Cell Development or Response
Authors: Velez Maria-Gabriela , Kane Melissa , Liu Sucai , Gauld Stephen B. , Cambier John C. , Torres Raul M. , Pelanda Roberta
Published: April 2014

B cells expressing two different Igκ L chains (allotype included) have been occasionally observed. To determine frequency and function of these cells, we have analyzed gene-targeted mice that carry a human and a mouse Igk C region genes. Using different methodologies, we found that cells expressing two distinct κ-chains were 1.4–3% of all B cells and that they were present in the follicular, marginal zone, and B1 mature B cell subsets. When stimulated in vitro with anti-IgM, dual κ surface-positive cells underwent activation that manifested with cell proliferation and/or up-regulation of activation markers and similar to single κ-expressing B cells. Yet, when activated by divalent reagents that bound only one of the two κ-chains, dual κ B cells responded suboptimally in vitro, most likely because of reduced Ag receptor cross-linking. Nonetheless, dual κ B cells participated in a SRBC-specific immune response in vivo. Finally, we found that Ig allotype-included B cells that coexpress autoreactive and nonautoreactive Ag receptors were also capable of in vitro responses following BCR aggregation. In summary, our studies demonstrate that Igκ allotype-included B cells are present in the mouse mature B cell population and are responsive to BCR stimulation both in vitro and in vivo. Moreover, because in vitro activation in response to anti-IgM was also observed in cells coexpressing autoreactive and nonautoreactive Abs, our studies suggest a potential role of allotype-included B cells in both physiological and pathological immune responses.
Stat5 Is Essential for Early B Cell Development but Not for B Cell Maturation and Function
Authors: Dai Xuezhi , Chen Yuhong , Di Lie , Podd Andrew , Li Geqiang , Bunting Kevin D. , Hennighausen Lothar , Wen Renren , Wang Demin
Published: April 2014

The two closely related Stat5 (Stat5A and Stat5B) proteins are activated by a broad spectrum of cytokines. However, with the complication of the involvement of Stat5A/5B in stem cell function, the role of Stat5A/5B in the development and function of lymphocytes, especially B cells, is not fully understood. In this study, we demonstrated that Stat5A/5B−/− fetal liver cells had severe diminution of B cell progenitors but clearly had myeloid progenitors. Consistently, the mutant fetal liver cells could give rise to hemopoietic progenitors and myeloid cells but not B cells beyond pro-B cell progenitors in lethally irradiated wild-type or Jak3−/− mice. Deletion of Stat5A/5B in vitro directly impaired IL-7-mediated B cell expansion. Of note, reintroduction of Stat5A back into Stat5A/5B−/− fetal liver cells restored their abilities to develop B cells. Importantly, CD19-Cre-mediated deletion of Stat5A/5B in the B cell compartment specifically impaired early B cell development but not late B cell maturation. Moreover, the B cell-specific deletion of Stat5A/5B did not impair splenic B cell survival, proliferation, and Ig production. Taken together, these data demonstrate that Stat5A/5B directly control IL-7-mediated early B cell development but are not required for B cell maturation and Ig production.
Protection from Lethal Infection by Adoptive Transfer of CD8 T Cells Genetically Engineered to Express Virus-Specific Innate Immune Receptor
Authors: Iizuka Koho , Nakajima Chigusa , Iizuka Yoshie-Matsubayashi , Takase Mitsuyo , Kato Takako , Noda Satoshi , Tanaka Kazuo , Kanagawa Osami
Published: April 2014

CMV infection is one of the most common complications in immunocompromised individuals, such as organ and bone marrow transplant patients. Both innate and adaptive immune responses are required for defense against CMV infection. In murine CMV (MCMV) infection, strains harboring the MCMV-specific NK cell activation receptor, Ly49H (Klra8), are resistant. In contrast, MCMV infection of mice lacking Ly49H gene causes early mortality due to uncontrolled viral replication. In this study, we report the successful protection of mice from lethal MCMV infection with gene-transferred polyclonal CD8 T cells. CD8 T cells expressing a chimeric receptor comprising Ly49H extracellular and CD3ζ cytoplasmic domains are capable of killing target cells expressing the MCMV protein, m157. CD8 T cells expressing the chimeric receptor protect mice in vivo from lethality in the acute phase of MCMV infection, leading to the establishment of long-term protection. These data provide proof-of-principle evidence that a novel strategy for harnessing CD8 cytolytic function through TCR-independent yet pathogen-specific receptor can result in effective protection of hosts from pathogens.
Clonal Expansion of CD8+ Effector T Cells in Childhood Tuberculosis
Authors: Jacobsen Marc , Detjen Anne K. , Mueller Henrik , Gutschmidt Andrea , Leitner Sandra , Wahn Ulrich , Magdorf Klaus , Kaufmann Stefan H. E.
Published: April 2014

The role of CD8+ T cells in human tuberculosis (TB) remains elusive. We analyzed the T cell repertoire and phenotype in 1) children with active TB (≤4 years), 2) healthy latently Mycobacterium tuberculosis-infected children, and 3) noninfected age-matched (tuberculin skin test-negative) controls. Ex vivo phenotyping of T cell subpopulations by flow cytometry revealed a significant increase in the proportion of CD8+CD45RO−CD62L−CD28−CD27− effector T cells (TEF) in the peripheral blood of children with active TB (22.1 vs 9.5% in latently M. tuberculosis-infected children, vs 8.5% in tuberculin skin test-negative controls). Analyses of TCR variable β-chains revealed markedly skewed repertoires in CD8+ TEF and effector memory T cells. Expansions were restricted to single TCR variable β-chains in individual donors indicating clonal growth. CDR3 spectratyping and DNA sequencing verified clonal expansion as the cause for CD8+ effector T cell enrichment in individual TB patients. The most prominent enrichment of highly similar TEF clones (>70% of CD8+ TEF) was found in two children with active severe TB. Therefore, clonal expansion of CD8+ TEF occurs in childhood TB with potential impact on course and severity of disease.
Biodistribution Studies of Epithelial Cell Adhesion Molecule (EpCAM)-Directed Monoclonal Antibodies in the EpCAM-Transgenic Mouse Tumor Model
Authors: Kosterink Jos G. W. , McLaughlin Pamela M. J. , Lub-de Hooge Marjolijn N. , Hendrikse Harry H. , van Zanten Jacoba , van Garderen Evert , Harmsen Martin C. , de Leij Lou F. M. H.
Published: April 2014

The human pancarcinoma-associated epithelial cell adhesion molecule (EpCAM) (EGP-2, CO17-1A) is a well-known target for carcinoma-directed immunotherapy. Mouse-derived mAbs directed to EpCAM have been used to treat colon carcinoma patients showing well-tolerable toxic side effects but limited antitumor effects. Humanized or fully human anti-EpCAM mAbs may induce stronger antitumor activity, but proved to produce severe pancreatitis upon use in patients. To evaluate treatment-associated effects before a clinical trial, we have generated a transgenic mouse tumor model that expresses human EpCAM similar to carcinoma patients. In this study, we use this model to study the in vivo behavior of two humanized and one mouse-derived anti-EpCAM mAb, i.e., MOC31-hFc, UBS54, and MOC31. The pharmacokinetics and tissue distribution of the fully human mAb UBS54 and the mouse-derived MOC31 were largely the same after injection in tumor-bearing transgenic mice, whereas the molecularly engineered, humanized MOC31-hFc behaved differently. Injection of UBS54 and MOC31 resulted in significant, dose-dependent uptake of mAb in EpCAM-expressing normal and tumor tissues, accompanied by a drop in serum level, whereas injection of MOC31-hFc resulted in uptake in tumor tissue, limited uptake by normal tissues, and slow blood clearance. It is concluded that the EpCAM-transgenic mouse model provides valuable insights into the potential behavior of humanized anti-EpCAM mAbs in patients. mAbs sharing the same epitope and isotype but constructed differently were shown to behave differently in the model, indicating that the design of mAbs is important for eventual success in in vivo application.
Honokiol, a Natural Plant Product, Inhibits Inflammatory Signals and Alleviates Inflammatory Arthritis
Authors: Munroe Melissa E. , Arbiser Jack L. , Bishop Gail A.
Published: April 2014

Honokiol (HNK), a phenolic compound isolated and purified from magnolia, has been found to have a number of pharmacologic benefits, including anti-angiogenic and anti-inflammatory properties. HNK has long been used in traditional Asian medicine without toxic side effects. We and others have extensively studied signaling to B cells by CD40 and its Epstein Barr viral mimic, latent membrane protein 1 (LMP1), which has been implicated in exacerbation of chronic autoimmune disease. We asked whether HNK could inhibit CD40 and LMP1 inflammatory signaling mechanisms. In vivo, HNK stabilized the severity of symptomatic collagen-induced arthritis in both CD40-LMP1 transgenic mice and their congenic C57BL/6 counterparts. Ex vivo studies, including collagen-specific serum Ab and Ag recall responses, as well as CD40 or LMP1-mediated activation of splenic B cells, supported the anti-inflammatory effects of HNK. In mouse B cell lines expressing the human CD40-LMP1 chimeric receptor, CD40- and LMP1-mediated NF-κB and AP-1 activation were abrogated in a dose-dependent manner, with a concomitant decrease in TNF-α and IL-6. These promising findings suggest that the nontoxic anti-inflammatory properties of HNK could be valuable for blocking the autoimmune response.
Antiparallel Segregation of Notch Components in the Immunological Synapse Directs Reciprocal Signaling in Allogeneic Th:DC Conjugates
Authors: Luty Winifred H. , Rodeberg David , Parness Jerome , Vyas Yatin M.
Published: April 2014

Direct T cell allorecognition underlies the development of a vigorous immune response in the clinical setting of acute graft rejection. The Notch pathway is an important regulator of Th immune responses, yet the molecular underpinnings of directional Notch signaling, otherwise critical for binary cell fate decisions, are unknown during autologous or allogeneic Th:DC interactions. Using the development of immune synapses (IS) in the allogeneic, human physiological Th:DC interaction, we demonstrate that Th-Notch1 receptor and DC-Notch ligands (Delta-like1, Jagged1) cluster in their apposed central-supramolecular-activation-clusters (cSMAC), whereas DC-Notch1 receptor and Th-Notch ligands cluster in their apposed peripheral-SMAC (pSMAC). Numb, a negative regulator of Notch, is excluded from the IS-microdomains where Notch1 receptor accumulates. This antiparallel arrangement across the partnering halves of the IS supports reciprocal Notch signal propagation in the DC-to-Th direction via the cSMAC and Th-to-DC direction via the pSMAC. As a result, processed Notch1 receptor (Notch-intracellular-domain, NICD1) and its ligands, as well as their downstream targets, HES-1 and phosphorylated-STAT3, accumulate in the nuclei of both cell-types. There is also enhancement of GLUT1 expression in both cell-types, as well as increased production of Th-IFN-γ. Significantly, neutralizing Notch1R Ab inhibits NICD1 and HES-1 nuclear translocation, and production of IFN-γ. In contrast, the IS formed during Ag-nonspecific, autologous Th:DC interaction is immature, resulting in failure of Notch1 receptor segregation and subsequent nuclear translocation of NICD1. Our results provide the first evidence for the asymmetric recruitment of Notch components in the Th:DC immunological synapse, which regulates the bidirectional Notch signal propagation.
Urotensin II is a New Chemotactic Factor for UT Receptor-Expressing Monocytes
Authors: Segain Jean-Pierre , Rolli-Derkinderen Malvyne , Gervois Nadine , Raingeard de la Blétière Diane , Loirand Gervaise , Pacaud Pierre
Published: April 2014

Urotensin II (U-II), a vasoactive cyclic neuropeptide which activates the G protein-coupled receptor UT receptor, exerts various cardiovascular effects and may play a role in the pathophysiology of atherosclerosis. In this study, we report that the UT receptor is expressed and functional on human PBMC and rat splenocytes. PBMC surface expression of the UT receptor was mainly found in monocytes and NK cells, also in a minority of B cells, but not in T cells. Stimulation of monocytes with LPS increased UT receptor mRNA and protein expression. Cloning and functional characterization of the human UT receptor gene promoter revealed the presence of NF-κB-binding sites involved in the stimulation of UT receptor gene expression by LPS. Activation of the UT receptor by U-II induced chemotaxis with maximal activity at 10 and 100 nM. This U-II effect was restricted to monocytes. Analysis of the signaling pathway involved indicated that U-II-mediated chemotaxis was related to RhoA and Rho kinase activation and actin cytoskeleton reorganization. The present results thus identify U-II as a chemoattractant for UT receptor-expressing monocytes and indicate a pivotal role of the RhoA-Rho kinase signaling cascade in the chemotaxis induced by U-II.
Lack of Reactive Oxygen Species Breaks T Cell Tolerance to Collagen Type II and Allows Development of Arthritis in Mice
Authors: Hultqvist Malin , Bäcklund Johan , Bauer Kristin , Gelderman Kyra A. , Holmdahl Rikard
Published: April 2014

The view on reactive oxygen species (ROS) in inflammation is currently shifting from being considered damaging toward having a more complex role in regulating inflammatory reactions. We recently demonstrated a role of ROS in regulation of animal models for the autoimmune disease rheumatoid arthritis. Low levels of ROS production, due to a mutation in the Ncf1 gene coding for the Ncf1 (alias p47phox) subunit of the NADPH oxidase complex, was shown to be associated with increased autoimmunity and arthritis severity in both rats and mice. To further investigate the role of ROS in autoimmunity, we studied transgenic mice expressing collagen type II (CII) with a mutation (D266E) in the immunodominant epitope that mimics the rat and human CII (i.e., mutated mouse collagen or MMC). This mutation results in a stronger binding of the epitope to the MHC class II molecule and leads to more pronounced tolerance and resistance to arthritis induced with rat CII. When the Ncf1 mutation was bred into these mice, tolerance was broken, resulting in enhanced T cell autoreactivity, high titers of anti-CII Abs, and development of severe arthritis. These findings highlight the importance of a sufficient ROS production in maintenance of tolerance to self-Ags, a central mechanism in autoimmune diseases such as rheumatoid arthritis. This is important as we, for the first time, can follow the effect of ROS on molecular mechanisms where T cells are responsible for either protection or promotion of arthritis depending on the level of oxygen species produced.
A Fusion Protein Consisting of IL-16 and the Encephalitogenic Peptide of Myelin Basic Protein Constitutes an Antigen-Specific Tolerogenic Vaccine That Inhibits Experimental Autoimmune Encephalomyelitis
Authors: Mannie Mark D. , Abbott Derek J.
Published: April 2014

To test a novel concept for the generation of tolerogenic vaccines, fusion proteins were constructed encompassing a tolerogenic or biasing cytokine and the major encephalitogenic peptide of guinea pig myelin basic protein (GPMBP; i.e., neuroantigen or NAg). The cytokine domain was predicted to condition APC while simultaneously targeting the covalently linked encephalitogenic peptide to the MHC class II Ag processing pathway of those conditioned APC. Rats were given three s.c. injections of cytokine-NAg in saline 1–2 wk apart and then at least 1 wk later were challenged with NAg in CFA. The rank order of tolerogenic activity in the Lewis rat model of EAE was NAgIL16 > IL2NAg > IL1RA-NAg, IL13NAg ≥ IL10NAg, GPMBP, GP69–88, and saline. NAgIL16 was also an effective inhibitor of experimental autoimmune encephalomyelitis when administered after an encephalitogenic challenge during the onset of clinical signs. Covalent linkage of the NAg and IL-16 was required for inhibition of experimental autoimmune encephalomyelitis. These data identify IL-16 as an optimal cytokine partner for the generation of tolerogenic vaccines and indicate that such vaccines may serve as Ag-specific tolerogens for the treatment of autoimmune disease.
Prostaglandin E2 Is a Major Inhibitor of Dendritic Cell Maturation and Function in Ixodes scapularis Saliva
Authors: Sá-Nunes Anderson , Bafica André , Lucas David A. , Conrads Thomas P. , Veenstra Timothy D. , Andersen John F. , Mather Thomas N. , Ribeiro José M. C. , Francischetti Ivo M. B.
Published: April 2014

Tick saliva is thought to contain a number of molecules that prevent host immune and inflammatory responses. In this study, the effects of Ixodes scapularis saliva on cytokine production by bone marrow-derived dendritic cells (DCs) from C57BL/6 mice stimulated by TLR-2, TLR-4, and TLR-9 ligands were studied. Saliva at remarkably diluted concentrations (<1/2000) promotes a dose-dependent inhibition of IL-12 and TNF-α production induced by all TLR ligands used. Using a combination of fractionation techniques (microcon filtration, molecular sieving, and reversed-phase chromatography), we unambiguously identified PGE2 as the salivary inhibitor of IL-12 and TNF-α production by DCs. Moreover, we have found that I. scapularis saliva (dilution 1/200; ∼10 nM PGE2) marginally inhibited LPS-induced CD40, but not CD80, CD86, or MHC class II expression. In addition, saliva significantly suppressed the ability of DCs to stimulate Ag-specific CD4+ T cell proliferation and IL-2 production. Notably, the effect of saliva on DC maturation and function was reproduced by comparable concentrations of standard PGE2. These findings indicate that PGE2 accounts for most inhibition of DC function observed with saliva in vitro. The role of salivary PGE2 in vector-host interaction and host immune modulation and inflammation in vivo is also discussed. This study is the first to identify molecularly a DC inhibitor from blood-sucking arthropods.
Both Infiltrating Regulatory T Cells and Insufficient Antigen Presentation Are Involved in Long-Term Cardiac Xenograft Survival
Authors: Chen Wenhao , Diao Jun , Stepkowski Stanislaw M. , Zhang Li
Published: April 2014

We have previously shown that pretransplant donor lymphocyte infusion (DLI) together with transient depletion of CD4+ T cells could induce permanent rat-to-mouse heart graft survival, whereas depleting CD4+ T cells alone failed to do so. In this study, we investigated the mechanism leading to long-term xenograft survival. We found that peripheral CD4+ T cells from DLI/anti-CD4-treated mice could mount rat heart graft rejection after adoptive transfer into B6 CD4−/− mice. Infusing donor-Ag-loaded mature dendritic cells (DCs) could break long-term cardiac xenograft survival in DLI/anti-CD4-treated mice. Interestingly, when the number and phenotype of graft-infiltrating cells were compared between anti-CD4- and DLI/anti-CD4-treated groups, we observed a significant increase in both the number and suppressive activity of αβ-TCR+CD3+CD4−CD8− double negative regulatory T cells and decrease in the numbers of CD4+ and CD8+ T cells in the xenografts of DLI/anti-CD4-treated mice. Moreover, there was a significant reduction in MHC class II-high DCs within the xenografts of DLI/anti-CD4-treated recipients. DCs isolated from the xenografts of anti-CD4- but not DLI/anti-CD4-treated recipients could stimulate CD4+ T cell proliferation. Our data indicate that functional anti-donor T cells are present in the secondary lymphoid organs of the mice that permanently accepted cardiac xenografts. Their failure to reject xenografts is associated with an increase in double negative regulatory T cells as well as a reduction in Ag stimulation by DCs found within grafts. These findings suggest that local regulatory mechanisms need to be taken into account to control anti-xenograft T cell responses.
Respiratory Syncytial Virus Synergizes with Th2 Cytokines to Induce Optimal Levels of TARC/CCL17
Authors: Monick Martha M. , Powers Linda S. , Hassan Ihab , Groskreutz Dayna , Yarovinsky Timur O. , Barrett Christopher W. , Castilow Elaine M. , Tifrea Delia , Varga Steven M. , Hunninghake Gary W.
Published: April 2014

Respiratory syncytial virus (RSV) is a ubiquitous virus that preferentially infects airway epithelial cells, causing asthma exacerbations and severe disease in immunocompromised hosts. Acute RSV infection induces inflammation in the lung. Thymus- and activation-regulated chemokine (TARC) recruits Th2 cells to sites of inflammation. We found that acute RSV infection of BALB/c mice increased TARC production in the lung. Immunization of BALB/c mice with individual RSV proteins can lead to the development of Th1- or Th2-biased T cell responses in the lung after RSV infection. We primed animals with a recombinant vaccinia virus expressing either the RSV fusion (F) protein or the RSV attachment (G) protein, inducing Th1- and Th2-biased pulmonary memory T cell responses, respectively. After RSV infection, TARC production significantly increased in the vaccinia virus G-primed animals only. These data suggest a positive feedback loop for TARC production between RSV infection and Th2 cytokines. RSV-infected lung epithelial cells cultured with IL-4 or IL-13 demonstrated a marked increase in the production of TARC. The synergistic effect of RSV and IL-4/IL-13 on TARC production reflected differential induction of NFκB and STAT6 by the two stimuli (both are in the TARC promoter). These findings demonstrate that RSV induces a chemokine TARC that has the potential to recruit Th2 cells to the lung.
Ig Heavy Chain Promotes Mature B Cell Survival in the Absence of Light Chain
Authors: Geraldes Pedro , Rebrovich Michelle , Herrmann Kai , Wong Jamie , Jäck Hans-Martin , Wabl Matthias , Cascalho Marilia
Published: April 2014

Survival of mature B cells is thought to depend on the BCR signaling (BCR) because ablation of either H chain (HC) expression or BCR signaling causes B cells to rapidly disappear. Whether a complete BCR is required for survival of mature B cells is not known. To address this question, we generated a mouse in which we can repress the expression of a transgenic Ig L chain (IgL) by doxycycline (IgL-repressible mouse). Repression of IgL abrogated expression. Surprisingly, however, IgL-negative B cells survived longer than 14 wk, expressed signal-competent HC on the cell’s surface, and active unfolded protein response factors. Like postgerminal center B cells, IgL-negative B cells were small lymphocytes, not dividing and expressed Bcl-6. Our results indicate that expression of unpaired HC, as it may occur as a consequence of Ag ligation, somatic hypermutation, or receptor editing, facilitates the survival of cells either by inducing receptor signaling or by inducing unfolded protein response and/or the expression of survival genes such as Bcl-6.
Eosinophils from Lineage-Ablated ΔdblGATA Bone Marrow Progenitors: The dblGATA Enhancer in the Promoter of GATA-1 Is Not Essential for Differentiation Ex Vivo
Authors: Dyer Kimberly D. , Czapiga Meggan , Foster Barbara , Foster Paul S. , Kang Elizabeth M. , Lappas Courtney M. , Moser Jennifer M. , Naumann Nora , Percopo Caroline M. , Siegel Steven J. , Swartz Jonathan M. , Ting-De Ravin SukSee , Rosenberg Helene F.
Published: April 2014

A critical role for eosinophils in remodeling of allergic airways was observed in vivo upon disruption of the dblGATA enhancer that regulates expression of GATA-1, which resulted in an eosinophil-deficient phenotype in the ΔdblGATA mouse. We demonstrate here that bone marrow progenitors isolated from ΔdblGATA mice can differentiate into mature eosinophils when subjected to cytokine stimulation ex vivo. Cultured ΔdblGATA eosinophils contain cytoplasmic granules with immunoreactive major basic protein and they express surface Siglec F and transcripts encoding major basic protein, eosinophil peroxidase, and GATA-1, -2, and -3 to an extent indistinguishable from cultured wild-type eosinophils. Fibroblast coculture and bone marrow cross-transplant experiments indicate that the in vivo eosinophil deficit is an intrinsic progenitor defect, and remains unaffected by interactions with stromal cells. Interestingly, and in contrast to those from the wild type, a majority of the GATA-1 transcripts from cultured ΔdblGATA progenitors express a variant GATA-1 transcript that includes a first exon (1EB), located ∼3700 bp downstream to the previously described first exon found in hemopoietic cells (1EA) and ∼42 bp upstream to another variant first exon, 1EC. These data suggest that cultured progenitors are able to circumvent the effects of the ΔdblGATA ablation by using a second, more proximal, promoter and use this mechanism to generate quantities of GATA-1 that will support eosinophil growth and differentiation.
Triggering of Dendritic Cell Responses after Exposure to Activated, but Not Resting, Apoptotic PBMCs
Authors: Johansson Ulrika , Walther-Jallow Lilian , Smed-Sörensen Anna , Spetz Anna-Lena
Published: April 2014

Dendritic cells (DCs) can be activated by signaling via pathogen receptors, by interaction with activated T cells or by exposure to inflammatory mediators. Clearance of apoptotic cells by DCs is generally considered a silent event that is not associated with an inflammatory response. Necrotic cell death, in contrast, leads to induction of inflammation. However, emerging data challenge the view of apoptotic cells as inherently nonimmunogenic. In this study, we report that the activation state of the apoptotic cell may determine whether the exposed DC becomes activated and rendered proficient in Ag presentation. We show that coculture with activated, but not resting, apoptotic PBMCs leads to up-regulation of surface expression of the costimulatory molecules CD80, CD83, and CD86 in human DCs as well as release of proinflammatory cytokines. Furthermore, we show that DCs exposed to allogeneic, activated apoptotic PBMCs induce proliferation and IFN-γ production in autologous T cells. Together, these findings show that activated apoptotic PBMCs per se provide an activation/maturation signal to DCs, suggesting that activated apoptotic PBMCs possess endogenous adjuvant properties.
Myeloid and Plasmacytoid Dendritic Cells Are Susceptible to Recombinant Adenovirus Vectors and Stimulate Polyfunctional Memory T Cell Responses
Authors: Loré Karin , Adams William C. , Havenga Menzo , Precopio Melissa L. , Holterman Lennart , Goudsmit Jaap , Koup Richard A.
Published: April 2014

Although replication-incompetent recombinant adenovirus (rAd) type 5 is a potent vaccine vector for stimulating T and B cell responses, high seroprevalence of adenovirus type 5 (Ad5) within human populations may limit its clinical utility. Therefore, alternative adenovirus serotypes have been studied as vaccine vectors. In this study, we characterized the ability of rAd5 and rAd35 to infect and induce maturation of human CD11c+ myeloid dendritic cells (MDCs) and CD123+ plasmacytoid dendritic cells (PDCs), and their ability to stimulate Ag-specific T cells. Both MDCs and PDCs were found to express the primary receptor for Ad35 (CD46) but not Ad5 (coxsackie-adenovirus receptor; CAR). Both dendritic cell (DC) subsets were also more susceptible to rAd35 than to rAd5. MDCs were more susceptible to both rAd35 and rAd5 than were PDCs. Whereas rAd35 used CD46 for entry into DCs, entry of rAd5 may be through a CAR-independent pathway. Exposure to rAd35 but not rAd5 induced high levels of IFN-α in PDCs and phenotypic differentiation in both DC subsets. MDCs and PDCs exposed to either rAd5 or rAd35 encoding for CMV pp65 were able to present pp65 and activate CMV-specific memory CD8+ and CD4+ T cells in a dose-dependent manner, but MDCs stimulated the highest frequencies of pp65-specific T cells. Responding T cells expressed multiple functions including degranulation (CD107a surface mobilization) and production of IFN-γ, IL-2, TNF-α, and MIP-1β. Thus, the ability of rAd35 to naturally target important DC subsets, induce their maturation, and appropriately present Ag to T cells may herald greater in vivo immunogenicity than has been observed with rAd5.
Genetic Engineering of the Major Timothy Grass Pollen Allergen, Phl p 6, to Reduce Allergenic Activity and Preserve Immunogenicity
Authors: Vrtala Susanne , Focke Margarete , Kopec Jolanta , Verdino Petra , Hartl Arnulf , Sperr Wolfgang R. , Fedorov Alexander A. , Ball Tanja , Almo Steve , Valent Peter , Thalhamer Josef , Keller Walter , Valenta Rudolf
Published: April 2014

On the basis of IgE epitope mapping data, we have produced three allergen fragments comprising aa 1–33, 1–57, and 31–110 of the major timothy grass pollen allergen Phl p 6 aa 1–110 by expression in Escherichia coli and chemical synthesis. Circular dichroism analysis showed that the purified fragments lack the typical α-helical fold of the complete allergen. Superposition of the sequences of the fragments onto the three-dimensional allergen structure indicated that the removal of only one of the four helices had led to the destabilization of the α helical structure of Phl p 6. The lack of structural fold was accompanied by a strong reduction of IgE reactivity and allergenic activity of the three fragments as determined by basophil histamine release in allergic patients. Each of the three Phl p 6 fragments adsorbed to CFA induced Phl p 6-specific IgG Abs in rabbits. However, immunization of mice with fragments adsorbed to an adjuvant allowed for human use (AluGel-S) showed that only the Phl p 6 aa 31–110 induced Phl p 6-specific IgG Abs. Anti-Phl p 6 IgG Abs induced by vaccination with Phl p 6 aa 31–110 inhibited patients’ IgE reactivity to the wild-type allergen as well as Phl p 6-induced basophil degranulation. Our results are of importance for the design of hypoallergenic allergy vaccines. They show that it has to be demonstrated that the hypoallergenic derivative induces a robust IgG response in a formulation that can be used in allergic patients.
Nonclassical IL-1β Secretion Stimulated by P2X7 Receptors Is Dependent on Inflammasome Activation and Correlated with Exosome Release in Murine Macrophages
Authors: Qu Yan , Franchi Luigi , Nunez Gabriel , Dubyak George R.
Published: April 2014

Several mechanistically distinct models of nonclassical secretion, including exocytosis of secretory lysosomes, shedding of plasma membrane microvesicles, and direct efflux through plasma membrane transporters, have been proposed to explain the rapid export of caspase-1-processed IL-1β from monocytes/macrophages in response to activation of P2X7 receptors (P2X7R) by extracellular ATP. We compared the contribution of these mechanisms to P2X7R-stimulated IL-1β secretion in primary bone marrow-derived macrophages isolated from wild-type, P2X7R knockout, or apoptosis-associated speck-like protein containing a C-terminal CARD knockout mice. Our experiments revealed the following: 1) a novel correlation between IL-1β secretion and the release of the MHC-II membrane protein, which is a marker of plasma membranes, recycling endosomes, multivesicular bodies, and released exosomes; 2) a common and absolute requirement for inflammasome assembly and active caspase-1 in triggering the cotemporal export of IL-1β and MHC-II; and 3) mechanistic dissociation of IL-1β export from either secretory lysosome exocytosis or plasma membrane microvesicle shedding on the basis of different requirements for extracellular Ca2+ and differential sensitivity to pharmacological agents that block activation of caspase-1 inflammasomes. Thus, neither secretory lysosome exocytosis nor microvesicle shedding models constitute the major pathways for nonclassical IL-1β secretion from ATP-stimulated murine macrophages. Our findings suggest an alternative model of IL-1β release that may involve the P2X7R-induced formation of multivesicular bodies that contain exosomes with entrapped IL-1β, caspase-1, and other inflammasome components.
IFN-γ-Mediated Survival Enables Human Neutrophils to Produce MCP-1/CCL2 in Response to Activation by TLR Ligands
Authors: Yoshimura Teizo , Takahashi Munehisa
Published: April 2014

TLRs are key elements of the pathogen recognition mechanism used by the host immune system. Neutrophils express almost all TLRs, and activation of TLRs, such as TLR2 and TLR4, has been shown to induce the production of proinflammatory cytokines and chemokines, potentially linking innate and adaptive immunity. In the present study, we investigated whether activation of TLRs induces neutrophil production of MCP-1/CCL2, a key mediator involved in the development of adaptive immunity. Activation of neutrophils with LPS, lipoteichoic acid, or N-palmitoyl-S-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-[R]-Cys-[S]-Ser-[S]-Lys did not induce significant MCP-1 production and release; however, the Th1 cytokine IFN-γ dramatically up-regulated MCP-1 production in cells activated with each TLR ligand. The majority of MCP-1 was released between 24 and 48 h of culture, indicating that this is a late event. The effect of IFN-γ appeared to be due to its antiapoptotic effect, but not priming effect, revealing a biological consequence of IFN-γ-induced neutrophil survival. Although IFN-γ failed to protect neutrophils from cell death at a higher dose of LPS, the p38 MAPK inhibitor SB203580 dramatically increased MCP-1 release and neutrophil survival at this LPS concentration. Thus, p38 MAPK plays a previously uncharacterized role in neutrophil function. Taken together, our results indicate that human neutrophils produce MCP-1 in a Th1 microenvironment and this neutrophil-derived MCP-1 potentially amplifies the development of Th1 adaptive responses.
CCR4-Expressing T Cell Tumors Can Be Specifically Controlled via Delivery of Toxins to Chemokine Receptors
Authors: Baatar Dolgor , Olkhanud Purevdorj , Newton Dianne , Sumitomo Kenya , Biragyn Arya
Published: April 2014

Expression of chemokine receptors by tumors, specifically CCR4 on cutaneous T cell lymphomas, is often associated with a poor disease outcome. To test the hypothesis that chemokine receptor-expressing tumors can be successfully controlled by delivering toxins through their chemokine receptors, we have generated fusion proteins designated chemotoxins: chemokines fused with toxic moieties that are nontoxic unless delivered into the cell cytosol. We demonstrate that chemokines fused with human RNase eosinophil-derived neurotoxin or with a truncated fragment of Pseudomonas exotoxin 38 are able to specifically kill tumors in vitro upon internalization through their respective chemokine receptors. Moreover, treatment with the thymus and activation-regulated chemokine (CCL17)-expressing chemotoxin efficiently eradicated CCR4-expressing cutaneous T cell lymphoma/leukemia established in NOD-SCID mice. Taken together, this work represents a novel concept that may allow control of growth and dissemination of tumors that use chemokine receptors to metastasize and circumvent immunosurveillance.
Molecular Analysis of Alloreactive CTL Post-Hemopoietic Stem Cell Transplantation
Authors: O’Keefe Christine L. , Gondek Lukasz , Davis Randall , Kuczkowski Elizabeth , Sobecks Ronald M. , Rodriguez Alexander , Narvaez Yadira , McIver Zachariah , Tuthill Ralph , Laughlin Mary , Bolwell Brian , Maciejewski Jaroslaw P.
Published: April 2014

The development of laboratory tests for the diagnosis and monitoring of graft-vs-host disease (GVHD) is hampered by a lack of knowledge of minor histocompatibility Ags triggering alloresponses. We hypothesized that the unique molecular structure of the TCR could be used as a marker for the unidentified Ags and exploited for molecular monitoring of GVHD posttransplant. To identify alloreactive T cell clones, we performed in vitro allostimulation cultures for a cohort of patients undergoing hemopoietic stem cell transplantation and determined the sequence of the CDR3 of immunodominant alloreactive clones; 10 corresponding clonotypes restricted to activated T cells were identified. As an alternative method for the identification of alloreactive clones, molecular TCR analysis was applied to biopsies of GVHD-affected tissues. Culture- and biopsy-derived clonotypes were used to design sequence-specific quantitative PCR assays to monitor the levels of putative allospecific clonotypes in posttransplant blood samples and subsequent biopsies. Because of the rational design of the methods used to identify immunodominant clonotypes, we were able to follow the behavior of potentially GVHD-specific T cells during the transplant course. Based on our results, we conclude that molecular T cell diagnostics can be a powerful tool for monitoring immune responses posttransplantation.
Structure and Function: Heat Shock Proteins and Adaptive Immunity
Authors: Javid Babak , MacAry Paul A. , Lehner Paul J.
Published: April 2014

Heat shock proteins (HSPs) have been implicated in the stimulation and generation of both innate and adaptive immunity. The ability of HSPs to bind antigenic peptides and deliver them to APCs is the basis of the generation of peptide-specific T lymphocyte responses both in vitro and in vivo. The different HSP families are genetically and biochemically unrelated, and the structural basis of peptide binding and the dynamic models of ligand interaction are known only for some of the HSPs. We examine the contribution of HSP structure to its immunological functions and the potential “immunological repertoire” of HSPs as well as the use of biophysical techniques to quantify HSP-peptide interactions and optimize vaccine design. Although biochemical evidence for HSP-mediated endogenous processing of Ag has now emerged, the issue of whether HSP-peptide complexes act as physiological sources of Ag in cross-presentation is controversial. We assess the contribution of biochemical studies in this field.