bluuebunny/crossref_metadata_2025 huggingface dataset:
Immune Modulation in Multiple Sclerosis Patients Treated with the Pregnancy Hormone Estriol
Authors: Soldan Samantha S. , Retuerto Ana Isabel Alvarez , Sicotte Nancy L. , Voskuhl Rhonda R.
Published: April 2014

The protective effect of pregnancy on putative Th1-mediated autoimmune diseases, such as multiple sclerosis and rheumatoid arthritis, is associated with a Th1 to Th2 immune shift during pregnancy. The hormone estriol increases during pregnancy and has been shown to ameliorate experimental autoimmune encephalomyelitis and collagen-induced arthritis. In addition, estrogens induce cytokine changes consistent with a Th1 to Th2 shift when administered in vitro to human immune cells and in vivo to mice. In a pilot trial, oral estriol treatment of relapsing remitting multiple sclerosis patients caused significant decreases in enhancing lesions on brain magnetic resonance imaging. Here, the immunomodulatory effects of oral estriol therapy were assessed. PBMCs collected longitudinally during the trial were stimulated with mitogens, recall Ags, and glatiramer acetate. Cytokine profiles of stimulated PBMCs were determined by intracellular cytokine staining (IL-5, IL-10, IL-12 p40, TNF-α, and IFN-γ) and cytometric bead array (IL-2, IL-4, IL-5, IL-10, TNF-α, and IFN-γ). Significantly increased levels of IL-5 and IL-10 and decreased TNF-α were observed in stimulated PBMC isolated during estriol treatment. These changes in cytokines correlated with reductions of enhancing lesions on magnetic resonance imaging in relapsing remitting multiple sclerosis. The increase in IL-5 was primarily due to an increase in CD4+ and CD8+ T cells, the increase in IL-10 was primarily due to an increase in CD64+ monocytes/macrophages with some effect in T cells, while the decrease in TNF-α was primarily due to a decrease in CD8+ T cells. Further study of oral estriol therapy is warranted in Th1-mediated autoimmune diseases with known improvement during pregnancy.
Cutting Edge: Stimulation with the Cognate Self-Antigen Induces Expression of the Ly49A Receptor on Self-Reactive T Cells Which Modulates Their Responsiveness
Authors: Saurer Leslie , Seibold Inge , Vallan Claudio , Held Werner , Mueller Christoph
Published: April 2014

NK cell self-tolerance is maintained by inhibitory receptors specific for MHC class I molecules. Inhibitory NK receptors are also expressed on memory CD8 T cells but their biological relevance on T cells is unclear. In this study, we describe the expression of the Ly49A receptor on a subset of autoreactive T cells which persist in mice double-transgenic for the lymphocytic choriomeningitis virus-derived peptide gp33 and a TCRαβ specific for the gp33. No Ly49A-expressing cells are found in TCRαβ single-transgenic mice, indicating that the presence of the autoantigen is required for Ly49A induction. Direct evidence for an Ag-specific initiation of Ly49A expression has been obtained in vitro after stimulation of autoreactive TCRαβ T cells with the cognate self-Ag. This expression of Ly49A substantially reduces Ag-specific activation of autoreactive T cells. These findings thus suggest that autoantigen-specific induction of inhibitory NK cell receptors on T cells may contribute to peripheral self-tolerance.
Cutting Edge: A Potent Adjuvant Effect of Ligand to Receptor Activator of NF-κB Gene for Inducing Antigen-Specific CD8+ T Cell Response by DNA and Viral Vector Vaccination
Authors: Miyahira Yasushi , Akiba Hisaya , Katae Masaharu , Kubota Kaori , Kobayashi Seiki , Takeuchi Tsutomu , García-Sastre Adolfo , Fukuchi Yoshinosuke , Okumura Ko , Yagita Hideo , Aoki Takashi
Published: April 2014

The ligand to receptor activator of NF-κB (RANK-L)/RANK interaction has been implicated in CD40 ligand/CD40-independent T cell priming by dendritic cells. In this report, we show that the coadministration of the RANK-L gene with a Trypanosoma cruzi gene markedly enhances the induction of Trypanosoma Ag-specific CD8+ T cells and improves the DNA vaccine efficacy. A similarly potent adjuvant effect of the RANK-L gene on the induction of Ag-specific CD8+ T cells was also observed when recombinant influenza virus expressing murine malaria Ag was used as an immunogen. In contrast, the coadministration of the CD40L gene was not effective in these systems. Our results demonstrated, for the first time, the potent immunostimulatory effect of the RANK-L gene to improve the CD8+ T cell-mediated immunity against infectious agents.
B Lymphocyte Development in Rabbit: Progenitor B Cells and Waning of B Lymphopoiesis
Authors: Jasper Paul J. , Zhai Shi-Kang , Kalis Susan L. , Kingzette Mae , Knight Katherine L.
Published: April 2014

In mammals that use gut-associated lymphoid tissues for expansion and somatic diversification of the B cell repertoire, B lymphopoiesis occurs early in ontogeny and does not appear to continue throughout life. In these species, including sheep, rabbit, and cattle, little is known about the pathway of B cell development and the time at which B lymphopoiesis wanes. We examined rabbit bone marrow by immunofluorescence with anti-CD79a and anti-μ and identified both proB and preB cells. The proB cells represent the vast majority of B-lineage cells in the bone marrow at birth and by incorporation of 5-bromo-2′-deoxyuridine, they appear to be a dynamic population. PreB cells reach maximum levels in the bone marrow at 3 wk of age, and B cells begin to accumulate at 7 wk of age. We cloned two VpreB and one λ5 gene and demonstrated that they are expressed within B-lineage cells in bone marrow. VpreB and λ5 coimmunoprecipitated with the μ-chain in lysates of 293T cells transfected with VpreB, λ5, and μ, indicating that VpreB, λ5, and μ-chains associate in a preB cell receptor-like complex. By 16 wk of age, essentially no proB or preB cells are found in bone marrow and by PCR amplification, B cell recombination excision circles were reduced 200-fold. By 18 mo of age, B cell recombination excision circles were reduced 500- to 1000-fold. We suggest that B cell development in the rabbit occurs primarily through the classical, or ordered, pathway and show that B lymphopoiesis is reduced over 99% by 16 wk of age.
Neuronal Repellent Slit2 Inhibits Dendritic Cell Migration and the Development of Immune Responses
Authors: Guan Hongbing , Zu Guorui , Xie Yi , Tang Hao , Johnson Martin , Xu Xiaochun , Kevil Christophe , Xiong Wen-Cheng , Elmets Craig , Rao Yi , Wu Jane Y. , Xu Hui
Published: April 2014

One of the essential functions of dendritic cells is to take up Ags in peripheral tissues and migrate into secondary lymphoid organs to present Ags to lymphocytes for the induction of immune responses. Although many studies have demonstrated that the migration of dendritic cells is closely associated with the development of immune responses, little is known about factors that inhibit dendritic cell migration and control the extent of immune responses to Ag stimulation. We show that Slit2, a neuronal repellent factor, is up-regulated in the skin by allergen sensitization and down-regulates the migration of Langerhans cells. The effect is mediated by direct interaction of Slit2 with cells that express a Slit-specific receptor, Robo1. Slit2-mediated inhibition of Langerhans cell migration results in suppression of contact hypersensitivity responses. These findings provide insights into a novel mechanism by which Slit2 functions as an anti-inflammatory factor for the initiation of immune responses.
CD43 Modulates Severity and Onset of Experimental Autoimmune Encephalomyelitis
Authors: Ford Mandy L. , Onami Thandi M. , Sperling Anne I. , Ahmed Rafi , Evavold Brian D.
Published: April 2014

Experimental autoimmune encephalomyelitis (EAE) is a mouse model of multiple sclerosis characterized by infiltration of activated CD4+ T lymphocytes into tissues of the CNS. This study investigated the role of CD43 in the induction and progression of EAE. Results demonstrate that CD43-deficient mice have reduced and delayed clinical and histological disease severity relative to CD43+/+ mice. This reduction was characterized by decreased CD4+ T cell infiltration of the CNS of CD43−/− mice but similar numbers of Ag-specific T cells in the periphery, suggesting a defect in T cell trafficking to the CNS. The absence of CD43 also affected cytokine production, as myelin oligodendrocyte glycoprotein (MOG) 35–55-specific CD43−/− CD4+ T cells exhibited reduced IFN-γ and increased IL-4 production. CD43−/− CD4+ MOG-primed T cells exhibited reduced encephalitogenicity relative to CD43+/+ cells upon adoptive transfer into naive recipients. These results suggest a role for CD43 in the differentiation and migration of MOG35–55-specific T cells in EAE, and identify it as a potential target for therapeutic intervention.
Proinflammatory Cytokines Dominate the Early Immune Response to Filarial Parasites
Authors: Babu Subash , Nutman Thomas B.
Published: April 2014

Although the early human immune response to the infective-stage larvae (L3) of Brugia malayi has not been well-characterized in vivo (because of the inability to determine the precise time of infection), the consensus has been that it must involve a predominant Th2 environment. We have set up an in vitro system to study this early immune response by culturing PBMC from unexposed individuals with live L3 of B. malayi. After 24 h of culture, T cell responses were examined by flow cytometry and by quantitative real-time RT-PCR for multiple cytokines. T cells were activated early following exposure to L3 as indicated by up-regulation of surface markers CD69 and CD71. The frequency of T cells expressing proinflammatory Th1 cytokines (IFN-γ, TNF-α, GM-CSF, IL-1α, and IL-8) but not Th2 cytokines (IL-4, IL-5, IL-6, IL-10, and IL-13) was significantly increased in response to L3. This T cell response occurred in both the CD4 and CD8 T cell compartment and was restricted to the effector/memory pool (CD45RO+). This T cell response was not due to LPS activity from the parasite or from its endosymbiont, Wolbachia; moreover, it required the presence of APC as well as direct contact with live L3. Real-time RT-PCR analysis of multiple cytokines in the T cells confirmed the increased expression of proinflammatory Th1 cytokines. Up-regulation of these cytokines suggests that the primary immune response to the live infective stage of the parasite is not predominantly Th2 in nature but rather dominated by a proinflammatory response.
Mycobacterium aviumInhibition of IFN-γ Signaling in Mouse Macrophages: Toll-Like Receptor 2 Stimulation Increases Expression of Dominant-Negative STAT1β by mRNA Stabilization
Authors: Alvarez Gail R. , Zwilling Bruce S. , Lafuse William P.
Published: April 2014

Mycobacterial infections of macrophages have been shown to inhibit the ability of the macrophage to respond to IFN-γ. We previously reported that Mycobacterium avium infection of mouse macrophages decreases IFN-γ-induced STAT1 tyrosine phosphorylation and STAT1 DNA binding. Because macrophages respond to M. avium through Toll-like receptor 2 (TLR2), we determined whether TLR2 stimulation inhibits the response to IFN-γ. Treatment of mouse RAW264.7 macrophages with TLR2 agonists inhibited the induction of IFN-γ-inducible genes by IFN-γ. In contrast to M. avium infection, TLR2 agonists did not inhibit the IFN-γ induction of DNA-binding activity of STAT1 and the tyrosine phosphorylation of STAT1α. Instead, IFN-γ induction of RAW264.7 cells treated with TLR2 agonists resulted in an increase in the tyrosine phosphorylation of the dominant-negative STAT1β. TLR2 stimulation of RAW264.7 cells increased both STAT1β protein and mRNA expression, suggesting that the increased STAT1β phosphorylation results from increased STAT1β expression. Because STAT1α and STAT1β mRNA have different 3′ untranslated regions, and 3′ untranslated regions can regulate mRNA stability, we examined the effects of TLR2 stimulation on mRNA stability. TLR2 stimulation of RAW264.7 cells increased the stability of STAT1β mRNA, while not affecting the stability of STAT1α mRNA. The ability of STAT1β to function as a dominant negative was confirmed by overexpression of STAT1β in RAW264.7 macrophages by transient transfection, which inhibited IFN-γ-induced gene expression. These findings suggest that M. avium infection of mouse macrophages inhibits IFN-γ signaling through a TLR2-dependent increase in STAT1β expression by mRNA stablization and a TLR2-independent inhibition of STAT1 tyrosine phosphorylation.
Surface Translocation of Pactolus Is Induced by Cell Activation and Death, but Is Not Required for Neutrophil Migration and Function
Authors: Garrison Sean , Hojgaard Andrias , Margraf Rebecca , Weis Janis J. , Weis John H.
Published: April 2014

Pactolus is a cell surface protein expressed by murine neutrophils. Pactolus is similar to the β integrins, except it lacks a functional metal ion-dependent adhesion site domain and is expressed without an α-chain partner. The majority of the Pactolus protein is held within the cell in dense granules in a highly glycosylated form. This intracellular form of Pactolus can be released to the cell surface following inflammatory activation or ligation of Pactolus on the cell surface. In addition, intracellular Pactolus translocates to the neutrophil surface following induction of apoptosis. Neutrophil activation studies suggest that Pactolus does not serve as an activating or phagocytic receptor for the neutrophil. To further define the function of Pactolus, a Pactolus-null mouse was generated. Pactolus-deficient animals mature appropriately and possess normal numbers of neutrophils, display appropriate migration into sites of inflammation, and combat introduced infections efficiently. These data suggest that Pactolus does not function as a neutrophil phagocytic or adhesion receptor, but may instead serve as a sugar-bearing ligand for lectin recognition by other cells.
Peroxisome Proliferator Activator Receptor-γ Ligands, 15-Deoxy-Δ12,14-Prostaglandin J2 and Ciglitazone, Reduce Systemic Inflammation in Polymicrobial Sepsis by Modulation of Signal Transduction Pathways
Authors: Zingarelli Basilia , Sheehan Maeve , Hake Paul W. , O’Connor Michael , Denenberg Alvin , Cook James A.
Published: April 2014

Peroxisome proliferator activator receptor-γ (PPARγ) is a nuclear receptor that controls the expression of several genes involved in metabolic homeostasis. We investigated the role of PPARγ during the inflammatory response in sepsis by the use of the PPARγ ligands, 15-deoxy-Δ12,14-PGJ2 (15d-PGJ2) and ciglitazone. Polymicrobial sepsis was induced by cecal ligation and puncture in rats and was associated with hypotension, multiple organ failure, and 50% mortality. PPARγ expression was markedly reduced in lung and thoracic aorta after sepsis. Immunohistochemistry showed positive staining for nitrotyrosine and poly(ADP-ribose) synthetase in thoracic aortas. Plasma levels of TNF-α, IL-6, and IL-10 were increased. Elevated activity of myeloperoxidase was found in lung, colon, and liver, indicating a massive infiltration of neutrophils. These events were preceded by degradation of inhibitor κBα (IκBα), activation of IκB kinase complex, and c-Jun NH2-terminal kinase and, subsequently, activation of NF-κB and AP-1 in the lung. In vivo treatment with ciglitazone or 15d-PGJ2 ameliorated hypotension and survival, blunted cytokine production, and reduced neutrophil infiltration in lung, colon, and liver. These beneficial effects of the PPARγ ligands were associated with the reduction of IκB kinase complex and c-Jun NH2-terminal kinase activation and the reduction of NF-κB and AP-1 DNA binding in the lung. Furthermore, treatment with ciglitazone or 15d-PGJ2 up-regulated the expression of PPARγ in lung and thoracic aorta and abolished nitrotyrosine formation and poly(ADP-ribose) expression in aorta. Our data suggest that PPARγ ligands attenuate the inflammatory response in sepsis through regulation of the NF-κB and AP-1 pathways.
Trachea Allograft Class I Molecules Directly Activate and Retain CD8+ T Cells That Cause Obliterative Airways Disease
Authors: Richards David M. , Dalheimer Stacy L. , Hertz Marshall I. , Mueller Daniel L.
Published: April 2014

Human T cells responding against transplanted allogeneic lung tissue have been implicated in late graft failure secondary to obliterative bronchiolitis. This obliterative airways disease (OAD) also develops in heterotopic murine tracheal allografts in association with graft infiltration by both CD8+ and CD4+ T cells. To date, there has been little evidence to suggest that directly alloreactive CD8+ T cells either promote chronic rejection or lead to the development of OAD following airway allotransplantation. Using Ld-specific TCR-Tg 2C CD8+ T cells adoptively transferred into wild-type B6 (H-2b) mice and the transplantation of BALB/c (H-2d) tracheal allografts, we now show that the direct recognition of donor-specific class I MHC molecules by host CD8+ T cells leads to their activation, clonal expansion within the graft, and differentiation to an effector phenotype with the capacity to induce airway fibrosis. In addition, these experiments demonstrate that ongoing direct alloantigen recognition within the transplanted airway tissue is necessary for the recruitment and retention of these directly alloreactive CD8+ T cells. Thus, these experiments are the first to definitively show a role for directly alloreactive CD8+ T cells in the chronic rejection that leads to OAD.
Estrogen Receptor α Mediates Estrogen’s Immune Protection in Autoimmune Disease
Authors: Liu Hong-biao , Loo Kyi Kyi , Palaszynski Karen , Ashouri Judith , Lubahn Dennis B. , Voskuhl Rhonda R.
Published: April 2014

Estrogens are known to influence a variety of autoimmune diseases, but it is not known whether their actions are mediated through classic estrogen receptor α (ERα). The presence of a functional ER was demonstrated in secondary lymphoid tissues, then ERα expression was shown at both the RNA and protein levels in these tissues. Use of ERα knockout mice revealed that both the estrogen-induced disease protection and the estrogen-induced reduction in proinflammatory cytokines were dependent upon ERα in the prototypic Th1-mediated autoimmune disease experimental autoimmune encephalomyelitis. These findings are central to the design of selective ER modifiers which aim to target biologic responses in specific organ systems.
Cutting Edge: In Vivo Induction of Integrated HIV-1 Expression by Mycobacteria Is Critically Dependent on Toll-Like Receptor 2
Authors: Báfica André , Scanga Charles A. , Schito Marco L. , Hieny Sara , Sher Alan
Published: April 2014

Mycobacterial infection has been implicated as a possible factor in AIDS progression in populations where HIV-1 and Mycobacterium tuberculosis are coendemic. In support of this concept, we have previously shown that HIV-1-transgenic (Tg) mice infected with mycobacteria display enhanced viral gene and protein expression. In this study, we demonstrate that the induction of HIV-1 observed in this model is dependent on Toll-like receptor 2 (TLR2), a pattern recognition receptor known to be involved in mycobacteria-host interaction. Spleen cells from HIV-1-Tg mice deficient in TLR2 (Tg/TLR2−/−) were found to be completely defective in p24 production induced in response to live M. tuberculosis or Mycobacterium avium as well as certain mycobacterial products. Importantly, following in vivo mycobacterial infection, Tg/TLR2−/− mice failed to display the enhanced HIV-1 gag/env mRNA and p24 protein synthesis exhibited by wild-type Tg animals. Together, these results argue that TLR2 plays a crucial role in the activation of HIV-1 expression by mycobacterial coinfections.
Baculovirus Induces an Innate Immune Response and Confers Protection from Lethal Influenza Virus Infection in Mice
Authors: Abe Takayuki , Takahashi Hitoshi , Hamazaki Hiroyuki , Miyano-Kurosaki Naoko , Matsuura Yoshiharu , Takaku Hiroshi
Published: April 2014

A recombinant baculovirus expressing the hemagglutinin gene of the influenza virus, A/PR/8/34 (H1N1), under the control of the chicken β-actin promoter, was constructed. To determine the induction of protective immunity in vivo, mice were inoculated with the recombinant baculovirus by intramuscular, intradermal, i.p., and intranasal routes and then were challenged with a lethal dose of the influenza virus. Intramuscular or i.p. immunization with the recombinant baculovirus elicited higher titers of antihemagglutinin Ab than intradermal or intranasal administration. However, protection from a lethal challenge of the influenza virus was only achieved by intranasal immunization of the recombinant baculovirus. Surprisingly, sufficient protection from the lethal influenza challenge was also observed in mice inoculated intranasally with a wild-type baculovirus, as evaluated by reductions in the virus titer, inflammatory cytokine production, and pulmonary consolidations. These results indicate that intranasal inoculation with a wild-type baculovirus induces a strong innate immune response, which protects mice from a lethal challenge of influenza virus.
The Immune Response Modifier and Toll-Like Receptor 7 Agonist S-27609 Selectively Induces IL-12 and TNF-α Production in CD11c+CD11b+CD8− Dendritic Cells
Authors: Doxsee Christie L. , Riter Tony R. , Reiter Michael J. , Gibson Shelia J. , Vasilakos John P. , Kedl Ross M.
Published: April 2014

IL-12 and TNF-α production by dendritic cells (DCs) is a critical step in the initiation of local inflammation and adaptive immune responses. We show in this study that a small molecule immune response modifier that is a Toll-like receptor 7 (TLR7) agonist induces IL-12 and TNF-α production from murine CD11c+CD11b+CD8− DCs, a subset not previously known for this activity. Stimulation of these DCs through TLR7 in vivo induces significant cytokine production even 12 h after initial stimulation, as well as migration of the DC into T cell zones of the lymphoid tissue. In contrast, stimulation through TLR4 and TLR9 induced IL-12 production predominantly from CD8+ DCs, consistent with previously published data. All TLR stimuli induced the increase in surface expression of the activation markers B7-1, B7-2, and class II in both CD8+ and CD8− DCs, demonstrating that CD8+ DCs do respond to TLR7-mediated stimuli. To date this is the only known stimuli to induce preferential cytokine production from CD8− DCs. Given the efficacy of TLR7 agonists as antiviral agents, the data collectively indicate that stimulation of CD8− DCs through TLR7 most likely plays a role in the generation of antiviral immune responses.
Early Defect Prethymic in Bone Marrow T Cell Progenitors in Athymicnu/nuMice
Authors: Chatterjea-Matthes Devavani , García-Ojeda Marcos E. , Dejbakhsh-Jones Sussan , Jerabek Libuse , Manz Markus G. , Weissman Irving L. , Strober Samuel
Published: April 2014

nu/nu mice fail to develop a thymus and mature T cells due to a defect in the whn gene encoding a transcription factor necessary for terminal epithelial cell differentiation. We investigated whether early T cell progenitor development in the nu/nu bone marrow is also defective. We demonstrated a maturation arrest of nu/nu marrow T cell progenitors associated with a lack of pTα gene expression and a failure to give rise to mature T cells in adoptive euthymic hosts. Wild-type hemopoietic stem cells rapidly matured into functional T cell progenitors in the marrow of euthymic or thymectomized but not nu/nu hosts. We show that defects in bone marrow prethymic T cell development can also contribute to T cell deficiency in nu/nu mice.
Functional Analysis of the TCR Binding Domain of Toxic Shock Syndrome Toxin-1 Predicts Further Diversity in MHC Class II/Superantigen/TCR Ternary Complexes
Authors: McCormick John K. , Tripp Timothy J. , Llera Andrea S. , Sundberg Eric J. , Dinges Martin M. , Mariuzza Roy A. , Schlievert Patrick M.
Published: April 2014

Superantigens (SAGs) aberrantly alter immune system function through simultaneous interaction with lateral surfaces of MHC class II molecules on APCs and with particular variable regions of the TCR β-chain (Vβ). To further define the interface between the bacterial SAG toxic shock syndrome toxin-1 (TSST-1) and the TCR, we performed alanine scanning mutagenesis within the putative TCR binding region of TSST-1 along the central α helix adjacent to the N-terminal α helix and the β7-β9 loop as well as with two universally conserved SAG residues (Leu137 and Tyr144 in TSST-1). Mutants were analyzed for multiple functional activities, and various residues appeared to play minor or insignificant roles in the TCR interaction. The locations of six residues (Gly16, Trp116, Glu132, His135, Gln136, and Gln139), each individually critical for functional activity as well as direct interaction with the human TCR Vβ2.1-chain, indicate that the interface occurs in a novel region of the SAG molecule. Based on these data, a model of the MHC/TSST-1/TCR ternary complex predicts similarities seen with other characterized SAGs, although the CDR3 loop of Vβ2.1 is probably involved in direct SAG-TCR molecular interactions, possibly contributing to the TCR Vβ specificity of TSST-1.
Repetitive Elements in Mammalian Telomeres Suppress Bacterial DNA-Induced Immune Activation
Authors: Gursel Ihsan , Gursel Mayda , Yamada Hiroshi , Ishii Ken J. , Takeshita Fumihiko , Klinman Dennis M.
Published: April 2014

Bacterial DNA contains immunostimulatory CpG motifs that trigger an innate immune response capable of promoting host survival following infectious challenge. Yet CpG-driven immune activation may also have deleterious consequences, ranging from autoimmune disease to death. We find that repetitive elements present at high frequency in mammalian telomeres, but rare in bacteria, down-regulate CpG-induced immune activation. Suppressive activity correlates with the ability of telomeric TTAGGG repeats to form G-tetrads. Colocalization of CpG DNA with Toll-like receptor 9 in endosomal vesicles is disrupted by these repetitive elements, although cellular binding and uptake remain unchanged. These findings are the first to establish that specific host-derived molecules can down-regulate the innate immune response elicited by a TLR ligand.
Alternate Class I MHC Antigen Processing Is Inhibited by Toll-Like Receptor Signaling Pathogen-Associated Molecular Patterns:Mycobacterium tuberculosis19-kDa Lipoprotein, CpG DNA, and Lipopolysaccharide
Authors: Tobian Aaron A. R. , Potter Nicholas S. , Ramachandra Lakshmi , Pai Rish K. , Convery Marilyn , Boom W. Henry , Harding Clifford V.
Published: April 2014

Pathogen-associated molecular patterns (PAMPs) signal through Toll-like receptors (TLRs) to activate immune responses, but prolonged exposure to PAMPs from Mycobacterium tuberculosis (MTB) and other pathogens inhibits class II MHC (MHC-II) expression and Ag processing, which may allow MTB to evade CD4+ T cell immunity. Alternate class I MHC (MHC-I) processing allows macrophages to present Ags from MTB and other bacteria to CD8+ T cells, but the effect of PAMPs on this processing pathway is unknown. In our studies, MTB and TLR-signaling PAMPs, MTB 19-kDa lipoprotein, CpG DNA, and LPS, inhibited alternate MHC-I processing of latex-conjugated Ag by IFN-γ-activated macrophages. Inhibition was dependent on TLR-2 for MTB 19-kDa lipoprotein (but not whole MTB or the other PAMPs); inhibition was dependent on myeloid differentiation factor 88 for MTB and all of the individual PAMPs. Inhibition of MHC-II and alternate MHC-I processing was delayed, appearing after 16 h of PAMP exposure, as would occur in chronically infected macrophages. Despite inhibition of alternate MHC-I Ag processing, there was no inhibition of MHC-I expression, MHC-I-restricted presentation of exogenous peptide or conventional MHC-I processing of cytosolic Ag. MTB 19-kDa lipoprotein and other PAMPs inhibited phagosome maturation and phagosome Ag degradation in a myeloid differentiation factor 88-dependent manner; this may limit availability of peptides to bind MHC-I. By inhibiting both MHC-II and alternate MHC-I Ag processing, pathogens that establish prolonged infection of macrophages (>16 h), e.g., MTB, may immunologically silence macrophages and evade surveillance by both CD4+ and CD8+ T cells, promoting chronic infection.
Murine Macrophages Produce Secretory Leukocyte Protease Inhibitor During Clearance of Apoptotic Cells: Implications for Resolution of the Inflammatory Response
Authors: Odaka Chikako , Mizuochi Toshiaki , Yang Jingxuan , Ding Aihao
Published: April 2014

Macrophage-derived secretory leukocyte protease inhibitor (SLPI) can be induced locally as well as systemically in response to microbial products such as LPS and lipotechoic acid. It is not known whether phagocytosis of apoptotic cells, an essential function of macrophages, can regulate expression and secretion of SLPI. In this study, we report that exposure of peritoneal macrophages of BALB/c mice or murine macrophage cell lines RAW264.7 and J774.1 to apoptotic target cells induced an elevation in SLPI secretion. Secreted SLPI retained its antichymotrypsin activity. SLPI expression in thymuses from BALB/c mice that had been injected with anti-CD3 Ab to induce apoptosis of thymocytes was also elevated both at the mRNA and protein levels. Colchicine, a microtubular inhibitor, blocked the internalization of apoptotic cells by macrophages but not SLPI secretion, suggesting that surface recognition of apoptotic cells is sufficient for the induction of SLPI. Exposure of RAW264.7 cells to apoptotic CTLL-2 cells induced both SLPI and TNF-α, and addition of IFN-γ inhibited SLPI but augmented TNF-α production. Transfection of either the secreted or a nonsecreted form of SLPI into RAW264.7 cells led to suppression of TNF-α production in response to apoptotic cells. Thus, macrophages secrete an increased amount of SLPI when encountering apoptotic cells, which may help to attenuate potential inflammation during clearance of these cells.
Pivotal Role of Stat4 and Stat6 in the Pathogenesis of the Lupus-Like Disease in the New Zealand Mixed 2328 Mice
Authors: Jacob Chaim O. , Zang Song , Li Lily , Ciobanu Voicu , Quismorio Frank , Mizutani Akiei , Satoh Minoru , Koss Michael
Published: April 2014

We have developed novel genetically lupus-prone (NZB × NZW)F1-derived congenic New Zealand mixed (NZM) 2328 lines, which are either Stat4- or Stat6-deficient. Our studies show that the deficiency of Stat4 and Stat6 significantly alters the phenotype of the lupus-like disease in NZM 2328 congenic mice. Specifically, Stat4-deficient NZM mice develop accelerated nephritis and increased mortality in the absence of high levels of autoantibodies including anti-dsDNA Abs, and in the presence of relatively reduced levels of IFN-γ. In contrast, Stat6-deficient NZM mice display a significant reduction in incidence of kidney disease, with a dramatic increase in survival, despite the presence of high levels of anti-dsDNA Abs. The lack of correlation between levels of these autoantibodies and kidney disease raises the question of the direct cause-effect relationships between the presence of autoantibodies and kidney disease. Furthermore, these results also question the apparent equation of the effect of Stat deficiency with loss of secretion or response to particular cytokines.
Inhibitory Signal Override Increases Susceptibility to Mercury-Induced Autoimmunity
Authors: Zheng Yan , Monestier Marc
Published: April 2014

After exposure to subtoxic doses of heavy metals such as mercury, H-2s mice develop an autoimmune syndrome consisting of the rapid production of IgG autoantibodies that are highly specific for nucleolar autoantigens and a polyclonal increase in serum IgG1 and IgE. In this study, we explore the role of two inhibitory immunoreceptors, CTLA-4 and FcγRIIB, in the regulation of mercury-induced autoimmunity. In susceptible mice treated with mercuric chloride (HgCl2), administration of a blocking anti-CTLA-4 Ab resulted in a further increase in anti-nucleolar autoantibodies and in total serum IgG1 levels. Furthermore, in some DBA/2 mice, which are normally resistant to heavy metal-induced autoimmunity, anti-CTLA-4 treatment leads to the production of anti-nucleolar Abs, thereby overcoming the genetic restriction of the disease. In mice deficient for the FcγRIIB, HgCl2 administration did not trigger autoantibody production, but resulted in an increase in IgE serum levels. Taken together, these results indicate that different inhibitory mechanisms regulate various manifestations of this autoimmune syndrome.
Enhanced Immunogenicity and Protective Efficacy Against Mycobacterium tuberculosis of Bacille Calmette-Guérin Vaccine Using Mucosal Administration and Boosting with a Recombinant Modified Vaccinia Virus Ankara
Authors: Goonetilleke Nilu P. , McShane Helen , Hannan Carolyn M. , Anderson Richard J. , Brookes Roger H. , Hill Adrian V. S.
Published: April 2014

Heterologous prime-boost immunization strategies can evoke powerful T cell immune responses and may be of value in developing an improved tuberculosis vaccine. We show that recombinant modified vaccinia virus Ankara, expressing Mycobacterium tuberculosis Ag 85A (M.85A), strongly boosts bacille Calmette-Guérin (BCG)-induced Ag 85A specific CD4+ and CD8+ T cell responses in mice. A comparison of intranasal (i.n.) and parenteral immunization of BCG showed that while both routes elicited comparable T cell responses in the spleen, only i.n. delivery elicited specific T cell responses in the lung lymph nodes, and these responses were further boosted by i.n. delivery of M.85A. Following aerosol challenge with M. tuberculosis, i.n. boosting of BCG with either BCG or M.85A afforded unprecedented levels of protection in both the lungs (2.5 log) and spleens (1.5 log) compared with naive controls. Protection in the lung correlated with the induction of Ag 85A-specific, IFN-γ-secreting T cells in lung lymph nodes. These findings support further evaluation of mucosally targeted prime-boost vaccination approaches for tuberculosis.
Cutting Edge: H-2DM Is Responsible for the Large Differences in Presentation Among Peptides Selected by I-Ak During Antigen Processing
Authors: Lovitch Scott B. , Petzold Shirley J. , Unanue Emil R.
Published: April 2014

We quantitated the amounts of peptides from hen egg-white lysozyme presented by I-Ak molecules in APC lines. The large chemical gradient of presentation of the four hen egg-white lysozyme epitopes observed in cell lines expressing HLA-DM or H-2DM (referred to in this study as DM) was significantly diminished in the T2.Ak line lacking DM. Differences in levels of presentation between wild-type and DM-deficient APC were observed for all four epitopes, but differences were most evident for the highest affinity epitope. As a result of these quantitative differences in display, presentation of all four epitopes to T cells was impaired in the line lacking DM. The binding affinity of the pool of naturally processed peptides from DM-expressing lines was higher than that from the DM-deficient line. Thus, using a direct biochemical approach in APC, we demonstrate that DM influences the selection of peptides bound to MHC class II by favoring high affinity peptides.
Systemic Overexpression of IL-10 Induces CD4+CD25+ Cell Populations In Vivo and Ameliorates Type 1 Diabetes in Nonobese Diabetic Mice in a Dose-Dependent Fashion
Authors: Goudy Kevin S. , Burkhardt Brant R. , Wasserfall Clive , Song Sihong , Campbell-Thompson Martha L. , Brusko Todd , Powers Matthew A. , Clare-Salzler Michael J. , Sobel Eric S. , Ellis Tamir M. , Flotte Terence R. , Atkinson Mark A.
Published: April 2014

Early systemic treatment of nonobese diabetic mice with high doses of recombinant adeno-associated virus (rAAV) vector expressing murine IL-10 prevents type 1 diabetes. To determine the therapeutic parameters and immunological mechanisms underlying this observation, female nonobese diabetic mice at 4, 8, and 12 wk of age were given a single i.m. injection of rAAV-murine IL-10 (104, 106, 108, and 109 infectious units (IU)), rAAV-vector expressing truncated murine IL-10 fragment (109 IU), or saline. Transduction with rAAV-IL-10 at 109 IU completely prevented diabetes in all animals injected at all time points, including, surprisingly, 12-wk-old animals. Treatment with 108 IU provided no protection in the 12-wk-old injected mice, partial prevention in 8-wk-old mice, and full protection in all animals injected at 4 wk of age. All other treatment groups developed diabetes at a similar rate. The rAAV-IL-10 therapy attenuated pancreatic insulitis, decreased MHC II expression on CD11b+ cells, increased the population of CD11b+ cells, and modulated insulin autoantibody production. Interestingly, rAAV-IL-10 therapy dramatically increased the percentage of CD4+CD25+ regulatory T cells. Adoptive transfer studies suggest that rAAV-IL-10 treatment alters the capacity of splenocytes to impart type 1 diabetes in recipient animals. This study indicates the potential for immunomodulatory gene therapy to prevent autoimmune diseases, including type 1 diabetes, and implicates IL-10 as a molecule capable of increasing the percentages of regulatory cells in vivo.
Dissociating the Enhancing and Inhibitory Effects of Pertussis Toxin on Autoimmune Disease
Authors: Su Shao Bo , Silver Phyllis B. , Wang Peng , Chan Chi-Chao , Caspi Rachel R.
Published: April 2014

Pertussis toxin (PT) has both enhancing and inhibitory effects on experimental autoimmune disease, depending on its time of administration relative to immunization. The inhibitory effect is due to blocking of Gi-coupled receptors by the enzymatic A subunit. In this study, we attribute the enhancing effect of PT to the cell-binding B subunit (PT-B). C57BL/6 mice, a strain that requires PT to develop experimental uveitis, were immunized with a retinal Ag and were injected with whole PT, PT-B, or vehicle. Disease and associated immunological responses were evaluated. The results showed that PT-B, determined to be free of biologically significant contamination with whole PT or with endotoxin, was able to mimic all the effects of PT with respect to disease induction, enhancement of delayed-type hypersensitivity, enhancement of lymphocyte proliferation, induction of an innate IL-12 response, and promotion of an adaptive IFN-γ response to the uveitogenic Ag. Our results suggest that PT-B is largely responsible for the disease-enhancing properties of PT.
Allele-Specific Expression of the IL-1α Gene in Human CD4+ T Cell Clones
Authors: Bayley Jean-Pierre , van Rietschoten Johanna G. I. , Bakker Aleida M. , van Baarsen Lisa , Kaijzel Eric L. , Wierenga Eddy A. , van der Pouw Kraan Tineke C. T. M. , Huizinga Tom W. J. , Verweij Cornelis L.
Published: April 2014

A number of reports have described the monoallelic expression of murine cytokine genes. Here we describe the monoallelic expression of the human IL-1α gene in CD4+ T cells. Analysis of peripheral blood T cell clones derived from healthy individuals revealed that the IL-1α gene shows predominantly monoallelic expression. Monoallelic expression was observed in Th0, Th1, and Th2 cell clones. In addition, we demonstrate monoallelic expression in T cell clones from rheumatoid arthritis patients derived from synovial fluid of the knee joint, suggesting that the occurrence of this phenomenon is not different from that in clones derived from healthy individuals. The finding of monoallelic expression of a cytokine gene in human CD4+ T cell clones provides evidence for allele-specific silencing/activation as another layer of regulation of IL-1α gene expression.
The Fas/Fas Ligand Pathway Is Important for Optimal Tumor Regression in a Mouse Model of CTL Adoptive Immunotherapy of Experimental CMS4 Lung Metastases
Authors: Caldwell Sheila A. , Ryan Mary H. , McDuffie Elwood , Abrams Scott I.
Published: April 2014

The mechanisms of CTL-mediated tumor regression in vivo remain to be fully understood. If CTL do mediate tumor regression in vivo by direct cytotoxicity, this may occur via two major effector mechanisms involving the secretion of perforin/granzymes and/or engagement of Fas by Fas ligand (FasL) expressed by the activated CTL. Although the perforin pathway has been considered the dominant player, it is unclear whether Fas-mediated cytotoxicity is additionally required for optimal tumor rejection. Previously, we produced H-2Ld-restricted CTL reactive against the CMS4 sarcoma, which expresses a naturally occurring rejection Ag recognized by these CTL and harbors a cytokine (IFN-γ plus TNF)-inducible, Fas-responsive phenotype. The adoptive transfer of these CTL to syngeneic BALB/c mice with minimal (day 3 established) or extensive (day 10 established) experimental pulmonary metastases resulted in strong antitumor responses. Here we investigated whether a FasL-dependent CTL effector mechanism was important for optimal tumor regression in this adoptive immunotherapy model. The approach taken was to compare the therapeutic efficacy of wild-type to FasL-deficient (gld) CTL clones by adoptive transfer. In comparison with wild-type CTL, gld-CTL efficiently mediated tumor cytolysis and produced comparable amounts of IFN-γ, after tumor-specific stimulation, as in vitro assessments of Ag recognition. Moreover, gld-CTL mediated comparably potent antitumor effects in a minimal disease setting, but were significantly less effective under conditions of an extensive tumor burden. Overall, under conditions of extensive lung metastases, these data revealed for the first time an important role for a FasL-dependent CTL effector mechanism in optimal tumor regression.
Spontaneous Membrane Transfer Through Homotypic Synapses Between Lymphoma Cells
Authors: Poupot Mary , Fournié Jean-Jacques
Published: April 2014

Formation of an immunological synapse by T, B, or NK cells is associated with an intercellular transfer of some membrane fragments from their respective target cells. This capture is thought to require effector cell activation by surface recognition of stimulatory ligand(s). However, spontaneous synaptic transfers between homotypic lymphoid cells has never been described. In this study, we show that without adding Ag, resting healthy lymphoid cells and several tumor cell lines are inactive. Conversely, however, some leukemia cell lines including the Burkitt’s lymphoma Daudi continuously uptake patches of autologous cell membranes. This intercellular transfer does not involve cytosol molecules or exosomes, but requires cell contact. In homotypic Daudi cell conjugates, this occurs through immunological synapses, involves constitutive protein kinase C and mitogen-activated protein/extracellular signal-regulated kinase kinase activity and strongly increases upon B cell receptor activation. Thus, spontaneous homosynaptic transfer may reflect the hitherto unsuspected autoreactivity of some leukemia cell lines.
Francisella tularensisSelectively Induces Proinflammatory Changes in Endothelial Cells
Authors: Forestal Colin A. , Benach Jorge L. , Carbonara Chateen , Italo Jaime K. , Lisinski Tracy J. , Furie Martha B.
Published: April 2014

Naturally acquired infections with Francisella tularensis, the bacterial agent of tularemia, occur infrequently in humans. However, the high infectivity and lethality of the organism in humans raise concerns that it might be exploited as a weapon of bioterrorism. Despite this potential for illicit use, the pathogenesis of tularemia is not well understood. To examine how F. tularensis interacts with cells of its mammalian hosts, we tested the ability of a live vaccine strain (LVS) to induce proinflammatory changes in cultured HUVEC. Living F. tularensis LVS induced HUVEC to express the adhesion molecules VCAM-1 and ICAM-1, but not E-selectin, and to secrete the chemokine CXCL8, but not CCL2. Stimulation of HUVEC by the living bacteria was partially suppressed by polymyxin B, an inhibitor of LPS, but did not require serum, suggesting that F. tularensis LVS does not stimulate endothelium through the serum-dependent pathway that is typically used by LPS from enteric bacteria. In contrast to the living organisms, suspensions of killed F. tularensis LVS acquired the ability to increase endothelial expression of both E-selectin and CCL2. Up-regulation of E-selectin and CCL2 by the killed bacteria was not inhibited by polymyxin B. Exposure of HUVEC to either live or killed F. tularensis LVS for 24 h promoted the transendothelial migration of subsequently added neutrophils. These data indicate that multiple components of F. tularensis LVS induce proinflammatory changes in endothelial cells in an atypical manner that may contribute to the exceptional infectivity and virulence of this pathogen.
CD1d-Restricted NKT Cells Express a Chemokine Receptor Profile Indicative of Th1-Type Inflammatory Homing Cells
Authors: Thomas Seddon Y. , Hou Runhua , Boyson Jonathan E. , Means Terry K. , Hess Christoph , Olson Douglas P. , Strominger Jack L. , Brenner Michael B. , Gumperz Jenny E. , Wilson S. Brian , Luster Andrew D.
Published: April 2014

CD1d-restricted T cells (NKT cells) are innate memory cells activated by lipid Ags and play important roles in the initiation and regulation of the immune response. However, little is known about the trafficking patterns of these cells or the tissue compartment in which they exert their regulatory activity. In this study, we determined the chemokine receptor profile expressed by CD1d-restricted T cells found in the peripheral blood of healthy volunteers as well as CD1d-restricted T cell clones. CD1d-restricted T cells were identified by Abs recognizing the invariant Vα24 TCR rearrangement or by binding to CD1d-Fc fusion tetramers loaded with α-GalCer. CD1d-restricted T cells in the peripheral blood and CD1d-restricted T cell clones expressed high levels of CXCR3, CCR5, and CCR6; intermediate levels of CXCR4 and CXCR6; and low levels of CXCR1, CCR1, CCR2, and CX3CR1, a receptor pattern often associated with tissue-infiltrating effector Th1 cells and CD8+ T cells. Very few of these cells expressed the lymphoid-homing receptors CCR7 or CXCR5. CCR4 was expressed predominantly on CD4+, but not on double-negative CD1d-restricted T cells, which may indicate differential trafficking patterns for these two functionally distinct subsets. CD1d-restricted T cell clones responded to chemokine ligands for CXCR1/2, CXCR3, CXCR4, CXCR6, CCR4, and CCR5 in calcium flux and/or chemotaxis assays. These data indicate that CD1d-restricted T cells express a chemokine receptor profile most similar to Th1 inflammatory homing cells and suggest that these cells perform their function in peripheral tissue sites rather than in secondary lymphoid organs.
Overlapping and Selective Roles of Endothelial Intercellular Adhesion Molecule-1 (ICAM-1) and ICAM-2 in Lymphocyte Trafficking
Authors: Lehmann Joachim C. U. , Jablonski-Westrich Dorothee , Haubold Uta , Gutierrez-Ramos Jose-C. , Springer Timothy , Hamann Alf
Published: April 2014

The integrin LFA-1 interacts with a variety of ligands termed ICAMs. ICAM-1 and ICAM-2 are both expressed on endothelium and serve as counterreceptors during lymphocyte trafficking. In this study, we analyzed their relative contribution to lymphocyte recirculation through lymph nodes and to recruitment into lung and inflamed skin by blocking mAbs against ICAM-1 and ICAM-2 and mice deficient for ICAM-1. The entry of lymphocytes into peripheral and mesenteric lymph nodes was found to be unaffected by the functional deletion of either ICAM-1 or ICAM-2. However, when both pathways were blocked, recirculation through lymph nodes was strongly reduced. Trapping of lymphocytes in the lung after i.v. injection is partly mediated by LFA-1/ICAM interactions; the data presented in this study show an exclusive role of ICAM-1 in LFA-1-dependent lung trapping. Similarly, ICAM-1, but not ICAM-2, was required for the migration of T effector cells into the inflamed skin. These results indicate that ICAM-1 and ICAM-2 have redundant functions in lymphocyte recirculation through lymph nodes, but ICAM-1 is unique in supporting migration into inflamed sites and trapping within the lung.