bluuebunny/crossref_metadata_2025 huggingface dataset:
Cutting Edge: The Dendritic Cell Cytoskeleton Is Critical for the Formation of the Immunological Synapse
Authors: Al-Alwan Monther M. , Rowden Geoffrey , Lee Timothy D. G. , West Kenneth A.
Published: April 2014

The binding of a T cell to an APC results in T cell actin cytoskeletal rearrangement leading to the formation of an immunological synapse. The APC cytoskeleton has been thought to play a passive role in this process. In this study, we demonstrate that dendritic cells (DC), unlike other APC, actively polarize their actin cytoskeleton during interaction with T cells. DC cytoskeletal rearrangement was critical for both the clustering and the activation of resting T cells. This study provides compelling evidence that the APC cytoskeleton plays an active role in the immunological synapse and may explain the unique ability of DC to activate resting T cells.
Cutting Edge: Expression of the C-C Chemokine Receptor CCR3 in Human Airway Epithelial Cells
Authors: Stellato Cristiana , Brummet Mary E. , Plitt James R. , Shahabuddin Syed , Baroody Fuad M. , Liu Mark C. , Ponath Paul D. , Beck Lisa A.
Published: April 2014

Chemokine-induced eosinophil chemotaxis is mediated primarily through the C-C chemokine receptor, CCR3. We have now detected CCR3 immunoreactivity on epithelial cells in biopsies of patients with asthma and other respiratory diseases. CCR3 mRNA was detected by Northern blot analysis after TNF-α stimulation of the human primary bronchial epithelial cells as well as the epithelial cell line, BEAS-2B; IFN-γ potentiated the TNF-α-induced expression. Western blots and flow cytometry confirmed the expression of CCR3 protein. This receptor is functional based on studies demonstrating eotaxin-induced intracellular Ca2+ flux and tyrosine phosphorylation of cellular proteins. The specificity of this functional response was confirmed by blocking these signaling events with anti-CCR3 mAb (7B11) or pertussis toxin. Furthermore, 125I-eotaxin binding assay confirmed that CCR3 expressed on epithelial cells have the expected ligand specificity. These studies indicate that airway epithelial cells express CCR3 and suggest that CCR3 ligands may influence epithelial cell functions.
Natural Autoreactive B Cells in Transgenic Mice Reproduce an Apparent Paradox to the Clonal Tolerance Theory
Authors: Koenig-Marrony Severine , Soulas Pauline , Julien Sylvie , Knapp Anne-Marie , Garaud Jean-Claude , Martin Thierry , Pasquali Jean-Louis
Published: April 2014

Naturally occurring autoreactive B cells are thought to be physically eliminated or rendered functionally silent through different mechanisms of tolerance. However, multireactive low affinity natural autoantibody-producing B cells seem to escape these mechanisms in normal adults and could constitute the B cell pool from which pathological autoantibodies can emerge. To analyze this apparent paradox to the clonal tolerance theory, we have made two transgenic mouse lines (μk, μ∂k) producing a natural low affinity multireactive human autoantibody. These models enable us to test both the central tolerance mechanisms (reactivity with single-stranded DNA) and the peripheral tolerance mechanisms after Ag administration. Not only are the multireactive B cells not deleted in the bone marrow, they circulate and remain in the periphery even after the prolonged administration of Ag, the presence of membrane IgD increasing the number of mature autoreactive B cells. Self-reactive B cells are shown to be autoantigen ignorant both in vivo and in vitro, but they are not anergic because they can be easily activated through both B cell receptor-dependent and -independent pathways. Thus, these mouse lines reproduce an apparent paradox to the clonal tolerance theory meriting further investigation of the biological significance of this phenomenon.
Th Type 1-Stimulating Activity of Lung Macrophages Inhibits Th2-Mediated Allergic Airway Inflammation by an IFN-γ-Dependent Mechanism
Authors: Tang Chibing , Inman Mark D. , van Rooijen Nico , Yang Pingchang , Shen Huahao , Matsumoto Koichiro , O’Byrne Paul M.
Published: April 2014

In the mucosal immune system, resident dendritic cells are specialized for priming Th2-polarized immunity, whereas the Ag-presenting activity of macrophages has been linked with the development of Th1 phenotype. As an immune switch toward Th1 can protect against Th2-mediated allergic response, this study investigated the capacity of lung macrophages to stimulate Th1 responses during the secondary exposure to inhaled allergen, thereby suppressing Th2-mediated allergic airway inflammation in a murine model of allergic asthma. Following airway macrophage depletion in OVA-sensitized mice, lung T cells defaulted to a phenotype that produced less Th1 (IFN-γ) and more Th2 (IL-4 and IL-5) cytokines, leading to more severe airway hyperreactivity and inflammation after intranasal Ag challenge. After OVA pulsing and adoptive transfer, lung macrophages selectively promoted a Th1 response in Ag-sensitized recipients and did not induce pulmonary eosinophilia. By contrast, OVA pulsing and adoptive transfer of a lung cell preparation, consisting of dendritic cells, B cells, and macrophages, promoted a Th2 response with an associated inflammatory response that was suppressed when macrophages were present and pretreated with IFN-γ, but exacerbated when macrophages were depleted before IFN-γ treatment. In addition, Th1-promoting activity of lung macrophages was not related to the autocrine production of IL-12p40. These results suggest that the Th1-promoting APC activity may be an inherent property of the lung macrophage population, and may play an important role, upon stimulation by IFN-γ, in antagonizing an ongoing Th2 immunity and Th2-dependent allergic responses.
Osteoprotegerin, a Crucial Regulator of Bone Metabolism, Also Regulates B Cell Development and Function
Authors: Yun Theodore J. , Tallquist Michelle D. , Aicher Alexandra , Rafferty Katherine L. , Marshall Aaron J. , Moon James J. , Ewings Maria K. , Mohaupt Mariette , Herring Susan W. , Clark Edward A.
Published: April 2014

Osteoprotegerin (OPG) is a CD40-regulated gene in B cells and dendritic cells (DCs). We investigated the role of OPG in the immune system by generating opg−/− mice. Like its role as a regulator of bone metabolism, OPG also influences processes in the immune system, notably in B cell development. Ex vivo, opg−/− pro-B cells have enhanced proliferation to IL-7, and in opg−/− spleen, there is an accumulation of type 1 transitional B cells. Furthermore, opg−/− bone marrow-derived DCs are more effective in stimulating allogeneic T cells than control DCs. When challenged with a T-dependent Ag, opg−/− mice had a compromised ability to sustain an IgG3 Ag-specific response. Thus, in the immune system, OPG regulates B cell maturation and development of efficient Ab responses.
The Human Endoplasmic Reticulum Molecular Chaperone BiP Is an Autoantigen for Rheumatoid Arthritis and Prevents the Induction of Experimental Arthritis
Authors: Corrigall Valerie M. , Bodman-Smith Mark D. , Fife Mark S. , Canas Benito , Myers Linda K. , Wooley Paul H. , Soh Cecilia , Staines Norman A. , Pappin Darryl J. C. , Berlo Suzanne E. , van Eden Willem , van der Zee Ruurd , Lanchbury Jerry S. , Panayi Gabriel S.
Published: April 2014

Rheumatoid arthritis (RA) is the most common, crippling human autoimmune disease. Using Western blotting and tandem mass spectroscopy, we have identified the endoplasmic reticulum chaperone BiP, a 78-kDa glucose-regulated protein, as a possible autoantigen. It preferentially stimulated increased proliferation of synovial T cells from patients with RA but not from patients with other arthritides. Mice with established collagen- or pristane-induced arthritis developed IgG Abs to BiP. Although BiP injected in CFA failed to induce arthritis in several strains of rats and mice, including HLA-DR4+/−- and HLA-DR1+/+-transgenic animals, it completely inhibited the development of arthritis when given i.v. 1 wk before the injection of type II collagen arthritis. Preimmunization with BiP suppressed the development of adjuvant arthritis in Lewis rats in a similar manner. This is the first report of a mammalian chaperone that is an autoantigen in human RA and in experimental arthritis and that can also prevent the induction of experimental arthritis. These findings may stimulate the development of new immunotherapies for the treatment of RA.
Infection of Human Dendritic Cells by Dengue Virus Causes Cell Maturation and Cytokine Production
Authors: Ho Ling-Jun , Wang Jaang-Jiun , Shaio Men-Fang , Kao Chuan-Liang , Chang Deh-Ming , Han Shou-Wha , Lai Jenn-Haung
Published: April 2014

Dengue virus (DV) infection is a major problem in public health. It can cause fatal diseases such as Dengue hemorrhagic fever and Dengue shock syndrome. Dendritic cells (DC) are professional APCs required for establishing a primary immune response. Here, we investigated the role of human PBMC-derived DC in DV infection. Using different techniques, including plaque assay, flow cytometry analysis, nested RT-PCR, and confocal microscope and electron microscope examinations, we show that DV can enter cultured human DC and produce virus particles. After entrance, DV could be visualized in cystic vesicles, vacuoles, and the endoplasmic reticulum. The DV-infected DC also showed proliferation and hypertrophy of the endoplasmic reticulum as well as the swollen mitochondria. In addition, the DV-stimulated DC could express maturation markers such as B7-1, B7-2, HLA-DR, CD11b, and CD83. Furthermore, the infection of DC by DV induced production of TNF-α and IFN-α, but not IL-6 and IL-12. Although DC underwent spontaneous apoptosis in the absence of feeding cytokines, this process appeared to be delayed after DV infection. Our observations provide important information in understanding the pathogenesis of DV infection.
A Receptor Presentation Hypothesis for T Cell Help That Recruits Autoreactive B Cells
Authors: Zhang Xianghua , Smith Diana S. , Guth Amanda , Wysocki Lawrence J.
Published: April 2014

To uncover mechanisms that drive spontaneous expansions of autoreactive B cells in systemic lupus erythematosus, we analyzed somatic mutations in variable region genes expressed by a panel of (NZB × SWR)F1 hybridomas representing a large, spontaneously arising clone with specificity for chromatin. A single mutation within the Jκ intron that was shared by all members of the lineage indicated that the clone emanated from a single mutated precursor cell and led to the prediction that a somatic mutation producing a functionally decisive amino acid change in the coding region would also be universally shared. Upon cloning and sequencing the corresponding germline VH gene, we found that two replacement somatic mutations in FR1 and CDR2 were indeed shared by all seven clone members. Surprisingly, neither mutation influenced Ab binding to chromatin; however, one of them produced a nonconservative amino acid replacement in a mutationally “cold” region of FR1 and created an immunodominant epitope for class II MHC-restricted T cells. The epitope was restricted by IAq (SWR), and the SWR MHC locus is associated with systemic lupus erythematosus in (NZB × SWR)F1 mice. These, and related findings, provoke the hypothesis that autoreactive B cells may be recruited by a “receptor presentation” mechanism involving cognate interactions between T cells and somatically generated V region peptides that are self-presented by B cells.
Functional Analysis of the Molecular Factors Controlling Qa1-Mediated Protection of Target Cells from NK Lysis
Authors: Gays Frances , Fraser Karen P. , Toomey Jennifer A. , Diamond Austin G. , Millrain Margaret M. , Dyson P. Julian , Brooks Colin G.
Published: April 2014

CD94/NKG2 receptors on mouse NK cells recognize the nonclassical class I molecule Qa1 and can deliver inhibitory signals that prevent NK cells from lysing Qa1-expressing cells. However, the exact circumstances under which Qa1 protects cells from NK lysis and, in particular, the role of the dominant Qa1-associated peptide, Qdm, are unclear. In this study, we examined in detail the lysis of Qa1-expressing cells by fetal NK cells that express CD94/NKG2 receptors for Qa1 but that lack receptors for classical class I molecules. Whereas mouse L cells and human C1R cells transfected with Qa1 were resistant to lysis by these effectors, Qa1-transfected TAP-deficient human T2 cells showed no resistance despite expressing high levels of surface Qa1. However, these cells could be efficiently protected by exposure to low concentrations of Qdm peptide or certain Qdm-related peptides. By contrast, even prolonged exposure of TAP-deficient RMA/S cells to high doses of Qdm peptide failed to induce levels of surface Qa1 detectable with a Qa1-specific mAb or to protect them from NK lysis, although such treatment induced sensitivity to lysis by Qa1-specific CTL. Collectively, these findings indicate that high surface expression of Qa1 is necessary but not sufficient for protection, and that effective protection requires the expression of sufficient levels of suitable Qa1-peptide complexes to overcome activatory signals. Results obtained with a series of substituted Qdm peptides suggest that residues at positions 3, 4, 5, and 8 of the Qdm sequence, AMAPRTLLL, are important for recognition of Qa1-Qdm complexes by inhibitory CD94/NKG2 receptors.
Stat5 and Sp1 Regulate Transcription of the Cyclin D2 Gene in Response to IL-2
Authors: Martino Anthony , Holmes James H. , Lord James D. , Moon James J. , Nelson Brad H.
Published: April 2014

The IL-2R promotes rapid expansion of activated T cells through signals mediated by the adaptor protein Shc and the transcription factor Stat5. The mechanisms that engage the cell cycle are not well defined. We report on the transcriptional regulation of the cell cycle gene cyclin D2 by the IL-2R. IL-2-responsive induction of a luciferase reporter gene containing 1624 bp of the cyclin D2 promoter/enhancer was studied in the murine CD8+ T cell line CTLL2. Reporter gene deletional analysis and EMSAs indicate an IL-2-regulated enhancer element flanks nucleotide −1204 and binds a complex of at least three proteins. The enhancer element is bound constitutively by Sp1 and an unknown factor(s) and inducibly by Stat5 in response to IL-2. The Stat5 binding site was essential for IL-2-mediated reporter gene activity, and maximum induction required the adjacent Sp1 binding site. Receptor mutagenesis studies in the pro-B cell line BA/FG (a derivative of the BA/F3 cell line) demonstrated a correlation between Stat5 activity and cyclin D2 mRNA levels when the Stat5 signal was isolated, disrupted, and then rescued. Further, a dominant-negative form of Stat5 lacking the trans-activation domain inhibited induction of cyclin D2 mRNA. We propose that the IL-2R regulates the cyclin D2 gene in part through formation of an enhancer complex containing Stat5 and Sp1.
Outer Membrane Protein-Specific Monoclonal Antibodies Protect SCID Mice from Fatal Infection by the Obligate Intracellular Bacterial Pathogen Ehrlichia chaffeensis
Authors: Shu-yi Li Julia , Yager Eric , Reilly Melissa , Freeman Christine , Reddy G. Roman , Reilly Andrew A. , Chu Frederick K. , Winslow Gary M.
Published: April 2014

Previous studies of Ehrlichia chaffeensis infection in the mouse have demonstrated that passive transfer of polyclonal Abs from resistant immunocompetent mice to susceptible SCID mice ameliorated infection and disease, even when Abs were administered during established infection. To identify particular Abs that could mediate bacterial clearance in vivo, E. chaffeensis-specific mAbs were generated and administered to infected SCID mice. Bacterial infection in the livers was significantly lowered after administration of either of two Abs of different isotypes (IgG2a and IgG3). Moreover, repeated administration of one Ab (Ec56.5; IgG2a) rescued mice from an otherwise lethal infection for at least 5 wk. Both protective Abs recognized the E. chaffeensis major outer membrane protein (OMP)-1g. Further studies revealed that both Abs recognized closely related epitopes within the amino terminus of the first hypervariable region of OMP-1g. Analyses of human sera showed that E. chaffeensis-infected patients also generated serological responses to OMP-1g hypervariable region 1, indicating that humans and mice recognize identical or closely related epitopes. These studies demonstrate that OMP-specific mAbs can mediate bacterial elimination in SCID mice, and indicate that Abs, in the absence of cell-mediated immunity, can play a significant role in host defense during infection by this obligate intracellular bacterium.
Protective Immunity Against the ProtozoanLeishmania chagasiIs Induced by Subclinical Cutaneous Infection with Virulent But Not Avirulent Organisms
Authors: Streit Judy A. , Recker Thomas J. , Filho Frederico Gueiros , Beverley Stephen M. , Wilson Mary E.
Published: April 2014

Protective immunity against Leishmania major is provided by s.c. immunization with a low dose of L. major promastigotes or with dihydrofolate-thymidylate synthase gene locus (DHFR-TS) gene knockout L. major organisms. Whether these vaccine strategies will protect against infection with other Leishmania species that elicit distinct immune responses and clinical syndromes is not known. Therefore, we investigated protective immunity to Leishmania chagasi, a cause of visceral leishmaniasis. In contrast to L. major, a high dose s.c. inoculum of L. chagasi promastigotes was required to elicit protective immunity. Splenocytes from mice immunized with a high dose produced significantly greater amounts of IFN-γ and lower TGF-β than mice immunized with a low dose of promastigotes. The development of protective immunity did not require the presence of NK cells. Protection was not afforded by s.c. immunization with either attenuated L. chagasi or with L. major promastigotes, and s.c. L. chagasi did not protect against infection with L. major. Subcutaneous immunization with DHFR-TS gene knockouts derived from L. chagasi, L. donovani, or L. major did not protect against L. chagasi infection. We conclude that s.c. inoculation of high doses of live L. chagasi causes a subclinical infection that elicits protective immune responses in susceptible mice. However, L. chagasi that have been attenuated either by long-term passage or during the raising of recombinant gene knockout organisms do not elicit protective immunity, either because they fail to establish a subclinical infection or because they no longer express critical antigenic epitopes.
Overexpression of IL-15 In Vivo Enhances Tc1 Response, Which Inhibits Allergic Inflammation in a Murine Model of Asthma
Authors: Ishimitsu Ryotaro , Nishimura Hitoshi , Yajima Toshiki , Watase Taketo , Kawauchi Hideyuki , Yoshikai Yasunobu
Published: April 2014

IL-15, a pleiotropic cytokine, is involved in the inflammatory responses in various infectious and autoimmune diseases. We have recently constructed IL-15-transgenic (Tg) mice, which have an increased number of memory-type CD8+ T cells in the peripheral lymphoid tissues. In the present study, we found that eosinophilia and Th2-type cytokine production in the airway were severely attenuated in OVA-sensitized IL-15-Tg mice following OVA inhalation. IL-15-Tg mice preferentially developed Tc1 responses mediated by CD8+ T cells after OVA sensitization, and in vivo depletion of CD8+ T cells by anti-CD8 mAb aggravated the allergic airway inflammation in IL-15-Tg mice following OVA inhalation. Adoptive transfer of CD8+ T cells from OVA-sensitized IL-15-Tg mice into normal mice before OVA sensitization suppressed Th2 response to OVA in the normal mice. These results suggest that overexpression of IL-15 in vivo suppresses Th2-mediated-allergic airway response via induction of CD8+ T cell-mediated Tc1 response.
Fibrinogen Promotes Neutrophil Activation and Delays Apoptosis
Authors: Rubel Carolina , Fernández Gabriela C. , Dran Graciela , Bompadre Macarena Beigier , Isturiz Martín A. , Palermo Marina S.
Published: April 2014

The acute phase of the inflammatory response involves an increase in the concentrations of different plasma proteins that include fibrinogen (Fbg) and multiple proinflammatory mediators. In parallel, neutrophil activation is thought to play a crucial role in several inflammatory conditions, and it has been recently demonstrated that Fbg specifically binds to the α-subunit of CD11b/CD18 on neutrophil surface. Although several reports have shown that CD11b engagement modulates neutrophil responses, the effect of human Fbg (hFbg), one of CD11b physiologic ligands, has not been exhaustively investigated. We have now shown that incubation of purified neutrophils with hFbg induces a transient and rapid elevation of free intracellular Ca2+. This early intracellular signal is accompanied by changes in the expression of neutrophil activation markers, including enhancement of CD11b and CD66b, and down-regulation of FcγRIII. In addition, we have evaluated the effect of hFbg on two functional events related to expression and resolution of inflammation: cytotoxic capacity and rate of neutrophil apoptosis. We have found that activation of neutrophils by hFbg resulted in both enhancement of phagocytosis and Ab-dependent cellular cytotoxicity, and delay of apoptosis. We conclude that during inflammatory processes, soluble Fbg could influence neutrophil responses, increasing and prolonging their functional capacity.
Expression of the Complement Anaphylatoxin C3a and C5a Receptors on Bronchial Epithelial and Smooth Muscle Cells in Models of Sepsis and Asthma
Authors: Drouin Scott M. , Kildsgaard Jens , Haviland Joie , Zabner Joseph , Jia Hong Pen , McCray Paul B. , Tack Brian F. , Wetsel Rick A.
Published: April 2014

The presence of the complement-derived anaphylatoxin peptides, C3a and C5a, in the lung can induce respiratory distress characterized by contraction of the smooth muscle walls in bronchioles and pulmonary arteries and aggregation of platelets and leukocytes in pulmonary vessels. C3a and C5a mediate these effects by binding to their specific receptors, C3aR and C5aR, respectively. The cells that express these receptors in the lung have not been thoroughly investigated, nor has their expression been examined during inflammation. Accordingly, C3aR and C5aR expression in normal human and murine lung was determined in this study by immunohistochemistry and in situ hybridization. In addition, the expression of these receptors was delineated in mice subjected to LPS- and OVA-induced models of inflammation. Under noninflamed conditions, C3aR and C5aR protein and mRNA were expressed by bronchial epithelial and smooth muscle cells of both human and mouse lung. C3aR expression increased significantly on both bronchial epithelial and smooth muscle cells in mice treated with LPS; however, in the OVA-challenged animals only the bronchial smooth muscle cells showed increased C3aR expression. C5aR expression also increased significantly on bronchial epithelial cells in mice treated with LPS, but was not elevated in either cell type in the OVA-challenged mice. These results demonstrate the expression of C3aR and C5aR by cells endogenous to the lung, and, given the participation of bronchial epithelial and smooth muscle cells in the pathology of diseases such as sepsis and asthma, the data suggest a role for these receptors during lung inflammation.
Resolution of Bronchial Hyperresponsiveness and Pulmonary Inflammation Is Associated with IL-3 and Tissue Leukocyte Apoptosis
Authors: Lloyd Clare M. , Gonzalo Jose-Angel , Nguyen Trang , Delaney Tracy , Tian Jane , Oettgen Hans , Coyle Anthony J. , Gutierrez-Ramos Jose-Carlos
Published: April 2014

We have used two models of murine pulmonary inflammation to investigate the signals responsible for the resolution of bronchial hyperresponsiveness (BHR). Both protocols involved two sensitizations with OVA followed by serial aerosolized challenge with OVA. We determined that administration of the second sensitization by aerosol (model A) was associated with a transient response, whereas administration by the i.p. route (model B) induced a sustained response, in the form of BHR and eosinophilia. This difference in kinetics was due solely to the route of the second Ag administration and was not associated with Ag dose or adjuvant. Differences in kinetics of lung eosinophilia/BHR were shown to be independent of IgE levels and IL-4 or IL-5. However, IL-3 levels in model A closely correlated with the rate of leukocyte clearance by apoptosis and were observed concomitant with a decline in BHR. Blockage of IL-3 in model B increased leukocyte apoptosis but reduced tissue eosinophilia and BHR. The use of mouse models in which a single different administration of allergen is associated with a failure/success to resolve inflammation and BHR by 72 h postchallenge indicates a link between IL-3 production, leukocyte apoptosis, and BHR responses.
Studies Using Leukemia Inhibitory Factor (LIF) Knockout Mice and a LIF Adenoviral Vector Demonstrate a Key Anti-Inflammatory Role for This Cytokine in Cutaneous Inflammation
Authors: Zhu Min , Oishi Kazuhiko , Chul Lee Sang , Patterson Paul H.
Published: April 2014

Previous work has implicated the cytokine leukemia inhibitory factor (LIF) in cutaneous inflammation, although results have differed as to whether LIF is pro- or anti-inflammatory in this setting. We examined edema, inflammatory cell infiltration, and cytokine responses following CFA injection in the adult mouse footpad. Inflammatory cell infiltration and edema are significantly enhanced when CFA is injected in LIF knockout mice as compared with injection of wild-type littermates. Moreover, local injection of an adenoviral vector encoding LIF suppresses both measures of inflammation. In contrast, injection of an adenoviral vector encoding β-galactosidase has no discernable effect on inflammation. In addition, comparison of the CFA responses in LIF knockout vs wild-type skin reveals that LIF is an important regulator of IL-1β, IL-6, IL-7, IL-2Rα, and IFN-γ in cutaneous inflammation. These and our previous data indicate that both endogenous and exogenous LIF are anti-inflammatory in the CFA model and that LIF is a key regulator of the cytokine cascade. The results also indicate that adenoviral gene delivery can be an effective therapeutic approach in this paradigm.
Low-Dose Estrogen Therapy Ameliorates Experimental Autoimmune Encephalomyelitis in Two Different Inbred Mouse Strains
Authors: Bebo Bruce F. , Fyfe-Johnson Amber , Adlard Kirsten , Beam Aaron G. , Vandenbark Arthur A. , Offner Halina
Published: April 2014

It has been proposed that homeostatic levels of estrogen can enhance female susceptibility to autoimmunity, whereas the heightened levels of estrogen associated with pregnancy are protective. This hypothesis was tested using the mouse model of experimental autoimmune encephalomyelitis (EAE). Diestrus (<100 pg/ml in serum) levels of 17β-estradiol were found to significantly reduce the clinical manifestations of active EAE in both male and female mice. Estriol was also effective but at doses below those previously established for pregnancy. The reduction in disease severity was accompanied by a coincident reduction in the number and size of inflammatory foci in the CNS of estrogen (17β-estradiol or estriol)-treated mice. Recipients of encephalitogenic T cells from low-dose estrogen-treated mice developed less severe paralysis than mice receiving T cells from placebo-treated mice. A modest shift in Th1/Th2 balance suggested that low dose estrogen therapy could bias the immune reaction toward a protective anti-inflammatory cytokine response. However, estrogen treatment at the onset of active EAE failed to reduce disease severity, a result that is consistent with the hypothesis that naive cells are more sensitive to sex hormones than differentiated effector cells. These data suggest that treatment with low doses of estrogen can reduce the capacity of developing myelin-reactive T cells to initiate disease and challenges the idea that increased susceptibility to autoimmunity in females is dependent on homeostatic levels of estrogen.
Effective Antigen-Specific Immunotherapy in the Marmoset Model of Multiple Sclerosis
Authors: McFarland Hugh I. , Lobito Adrian A. , Johnson Michele M. , Palardy Gregory R. , Yee Christina S. K. , Jordan E. Kay , Frank Joseph A. , Tresser Nancy , Genain Claude P. , Mueller John P. , Matis Louis A. , Lenardo Michael J.
Published: April 2014

Mature T cells initially respond to Ag by activation and expansion, but high and repeated doses of Ag cause programmed cell death and can suppress T cell-mediated diseases in rodents. We evaluated repeated systemic Ag administration in a marmoset model of experimental allergic encephalomyelitis that closely resembles the human disease multiple sclerosis. We found that treatment with MP4, a chimeric, recombinant polypeptide containing human myelin basic protein and human proteolipid protein epitopes, prevented clinical symptoms and did not exacerbate disease. CNS lesions were also reduced as assessed in vivo by magnetic resonance imaging. Thus, specific Ag-directed therapy can be effective and nontoxic in primates.
Innate and Adaptive Immune Responses to Nonvascular Xenografts: Evidence That Macrophages Are Direct Effectors of Xenograft Rejection
Authors: Fox Annette , Mountford Joanne , Braakhuis Andrea , Harrison Leonard C.
Published: April 2014

Nonvascularized xenograft rejection is T cell mediated, but is dependent on initial macrophage (Mφ) infiltration. We developed an i.p. transplant model to define the roles of Mφ and T cells in xenograft rejection. Nonobese diabetic or BALB/c mice were injected i.p. with xenogeneic, allogeneic, or syngeneic cells, and the responding cells in subsequent lavages were assessed by flow cytometry and adoptive transfer. Neutrophils and monocytes/elicited Mφ were rapidly recruited in response to xenogeneic pig (PK15 or spleen) cells and, to a significantly lesser extent, allogeneic cells. These innate responses preceded T cell infiltration and occurred in their absence in SCID mice. Syngeneic cells induced negligible neutrophil or Mφ responses. Neutrophils and Mφ induced by xenogeneic cells in SCID mice stimulated T cell recruitment after transfer to immunocompetent mice. T cells in turn were required for Mφ activation and xenogeneic cell rejection. Thus, Mφ harvested from immunocompetent but not SCID mice injected with xenogeneic cells expressed activation markers and rejected xenogeneic cells when transferred into SCID mice. These findings demonstrate the interdependent roles of Mφ and T cells in xenograft rejection. The requirement for Mφ reflects their ability to mount a rapid, local innate response that stimulates T cell recruitment and, having received T cell help, to act as direct effectors of rejection.
Cutting Edge Commentary: Origins of B-1 Cells
Authors: Wortis Henry H. , Berland Robert
Published: April 2014

The origin of B-1a cells, a minority population of B cells that express CD5, are abundant in coelomic cavities, and often produce autoantibodies, has been the subject of study for many years. Accumulating evidence demonstrates that the hypothesis that only B cells arising in fetal or neonatal tissues have the potential to become B-1a cells cannot be true. Rather, B cell receptor-mediated signaling initiated by ligation of autoantigen has now been shown to be required for induction of the B-1a phenotype. Furthermore, cells with a functional B-1a phenotype can be induced from adult precursors by appropriate Ag. At the same time, microenvironment-specific events may determine the likelihood that a given B cell, either adult or fetal derived, enters this pathway. CD5 expression and possibly localization to the peritoneum appear to provide some protection to autoreactive cells otherwise slated for elimination.
Cutting Edge: Peripheral Neuropeptides Attract Immature and Arrest Mature Blood-Derived Dendritic Cells
Authors: Dunzendorfer Stefan , Kaser Arthur , Meierhofer Christian , Tilg Herbert , Wiedermann Christian J.
Published: April 2014

Dendritic cells (DC) are highly motile and play a key role in mediating immune responses in various tissues and lymphatic organs. We investigated locomotion of mononuclear cell-derived DC at different maturation stages toward gradients of sensory neuropeptides in vitro. Calcitonin gene-related peptide, vasoactive intestinal polypeptide, secretin, and secretoneurin induced immature DC chemotaxis comparable to the potency of RANTES, whereas substance P and macrophage-inflammatory protein-3β stimulated immature cell migration only slightly. Checkerboard analyses revealed a true chemotactic response induced by neuropeptides. Upon maturation of DC, neuropeptides inhibited spontaneous, macrophage-inflammatory protein-3β- and 6Ckine-induced cell migration. Maturation-dependent changes in migratory behavior coincided with distinct neuropeptide-induced signal transduction in DC. Peripheral neuropeptides might guide immature DC to peripheral nerve fibers where high concentrations of these peptides can arrest the meanwhile matured cells. It seems that one function of sensory nerves is to fasten DC at sites of inflammation.
Cutting Edge: Stat6-Dependent Substrate Depletion Regulates Nitric Oxide Production
Authors: Rutschman Robert , Lang Roland , Hesse Matthias , Ihle James N. , Wynn Thomas A. , Murray Peter J.
Published: April 2014

The cytokines IL-4 and IL-13 inhibit the production of NO from activated macrophages through an unresolved molecular mechanism. We show here that IL-4 and IL-13 regulate NO production through depletion of arginine, the substrate of inducible NO synthase (iNOS). Inhibition of NO production from murine macrophages stimulated with LPS and IFN-γ by IL-4 or IL-13 was dependent on Stat6, cell density in the cultures, and pretreatment for at least 6 h. IL-4/IL-13 did not interfere with the expression or activity of iNOS but up-regulated arginase I (the liver isoform of arginase) in a Stat6-dependent manner. Addition of exogenous arginine completely restored NO production in IL-4-treated macrophages. Furthermore, impaired killing of the intracellular pathogen Toxoplasma gondii in IL-4-treated macrophages was overcome by supplementing l-arginine. The simple system of regulated substrate competition between arginase and iNOS has implications for understanding the physiological regulation of NO production.
Novel Secondary Ig VH Gene Rearrangement and In-Frame Ig Heavy Chain Complementarity-Determining Region III Insertion/Deletion Variants in De Novo Follicular Lymphoma
Authors: Kobrin Carol B. , Bendandi Maurizio , Kwak Larry W.
Published: April 2014

Human germinal center B cell tumors retain the ability of their nontransformed counterparts to somatically hypermutate Ig V genes by nucleotide substitution. Among a survey of 60 primary previously untreated, clonal, follicular lymphomas we have identified a rare VH rearrangement variant and two other in-frame nucleotide insertion/deletion variants within complementarity-determining region III of the Ig heavy chain. The neoplastic origin of the VH rearrangement variant was directly demonstrated in cells isolated by microdissection from malignant follicles. In all three cases a common clonal origin for the variants was demonstrated by complementarity-determining region III nucleotide sequence homology and shared somatic mutations in germline encoded positions in framework region IV. The monoclonal nature of the tumors was independently confirmed by demonstrating a single t(14;18) translocation breakpoint in the two cases with a detectable translocation. All the variants occurred in functional VH rearrangements, which in two cases were directly shown to encode functional Ab molecules. Both recombination-activating genes 1 and 2 were expressed in lymph node tumor cells containing the VH rearrangement variant, although recombination-activating gene expression among a panel of lymphomas was not limited to this variant.
Effector Function of Resting T Cells: Activation of Synovial Fibroblasts
Authors: Yamamura Yuji , Gupta Raj , Morita Yoshitaka , He Xiaogang , Pai Rajiv , Endres Judith , Freiberg Andrew , Chung Kevin , Fox David A.
Published: April 2014

Synovial tissue in rheumatoid arthritis is characterized by infiltration with large numbers of T lymphocytes and APCs as well as hyperplasia of synovial fibroblasts. Current understanding of the pathogenesis of RA includes the concept that synovial fibroblasts, which are essential to cartilage and bone destruction, are regulated by cytokines derived primarily from monocyte-macrophage cells. Recently it has been found that synovial fibroblasts can also function as accessory cells for T cell activation by superantigens and other stimuli. We have now found that highly purified resting T cells, even in the absence of T cell mitogens, induce activation of synovial fibroblasts when cocultured for 6–24 h. Such activation was evident by induction or augmentation of mRNA for stromelysin, IL-6, and IL-8, gene products important in joint inflammation and joint destruction. Furthermore, increased production of IL-6 and IL-8 was quantitated by intracellular cytokine staining and flow cytometry. This technique, previously used for analysis of T cell function, was readily adaptable for assays of synovial fibroblasts. Resting T cells also induced synovial fibroblasts to produce PGE2, indicating activation of expression of the cyclooxygenase 2 gene. Synergy was observed between the effects of IL-17, a cytokine derived from stimulated T cells that activates fibroblasts, and resting T lymphocytes. Various subsets of T cells, CD4+, CD8+, CD45RO+, and CD45RA+ all had comparable ability to induce synovial fibroblast activation. These results establish an Ag-independent effector function for resting T cells that is likely to be important in inflammatory compartments in which large numbers of T lymphocytes and fibroblasts can come into direct contact with each other.
IFN-γ-Dependent Inhibition of Tumor Angiogenesis by Tumor-Infiltrating CD4+ T Cells Requires Tumor Responsiveness to IFN-γ
Authors: Beatty Gregory L. , Paterson Yvonne
Published: April 2014

The importance of CD4+ T cells in the induction of an optimal antitumor immune response has largely been attributed to their ability to provide costimulatory signals for the priming of MHC class I-restricted CD8+ CTL. However, many reports have demonstrated a requirement for CD4+ T cells in the effector phase of tumor rejection indicating a greater responsibility for CD4+ T cells in controlling tumor outgrowth. We demonstrate here a critical role for CD4+ T cells in restraining initial tumor development through the inhibition of tumor angiogenesis. Using a tumor variant that is unresponsive to IFN-γ, we show that tumor responsiveness to IFN-γ is necessary for IFN-γ-dependent inhibition of tumor angiogenesis by CD4+ T cells. These studies reveal a pivotal role for CD4+ T cells in controlling early tumor development through inhibition of tumor angiogenesis.
Oral QS-21 Requires Early IL-4 Help for Induction of Mucosal and Systemic Immunity
Authors: Boyaka Prosper N. , Marinaro Mariarosaria , Jackson Raymond J. , van Ginkel Frederik W. , Cormet-Boyaka Estelle , Kirk Kevin L. , Kensil Charlotte R. , McGhee Jerry R.
Published: April 2014

The highly purified saponin derivative, QS-21, from the Quillaja saponaria Molina tree has been proved to be safe for parenteral administration and represents a potential alternative to bacterial enterotoxin derivatives as a mucosal adjuvant. Here we report that p.o. administration of QS-21 with the vaccine protein tetanus toxoid elicited strong serum IgM and IgG Ab responses, which were only slightly enhanced by further oral immunization. The IgG Ab subclass responses were predominantly IgG1 followed by IgG2b for the 50-μg p.o. dose of QS-21, whereas the 250-μg p.o. dose also induced IgG2a and IgG3 Abs. Low oral QS-21 doses induced transient IgE Ab responses 7 days after the primary immunization, whereas no IgE Ab responses were seen in mice given the higher QS-21 dose. Further, low but not high p.o. QS-21 doses triggered Ag-specific secretory IgA (S-IgA) Ab responses. Th cell responses showed higher IFN-γ (Th1-type) and lower IL-5, IL-6, and IL-10 (Th2-type) secretion after the high QS-21 p.o. dose than after low doses. Interestingly, the mucosal adjuvant activity of low oral QS-21 doses was diminished in IL-4−/− mice, suggesting a role for this cytokine in the initiation of mucosal immunity by oral QS-21. In summary, our results show that oral QS-21 enhances immunity to coadministered Ag and that different doses of QS-21 lead to distinct patterns of cytokine and serum Ab responses. We also show that an early IL-4 response is required for the induction of mucosal immunity by oral QS-21 as adjuvant.
Vγ2 TCR Repertoire Overlap in Different Anatomical Compartments of Healthy, Unrelated Rhesus Macaques
Authors: MacDougall Alex V. , Enders Patrick , Hatfield Glen , Pauza David C. , Rakasz Eva
Published: April 2014

γδ T cells show preferential homing that is characterized by biased TCR repertoire at different anatomical locations. The processes that regulate this compartmentalization are largely unknown. A model that allows repeated multiple sample procurement under different conditions and enables with relatively straightforward extrapolation to a human situation will facilitate our understanding. The peripheral blood Vγ2 T cell population is the best-characterized human γδ T cell subset. To determine its diversity at multiple immunocompartments matching blood, colon, and vagina samples from rhesus macaques were investigated. Four joining segments used in Vγ2-Jγ transcripts were identified, including one segment with no human counterpart. Like in humans, the rhesus peripheral blood Vγ2 TCR repertoire was limited and contained common sequences that were shared by genetically heterogeneous animals. Furthermore, this subset comprised several phylogenetically conserved Vγ2 complementarity-determining region 3 (CDR3) motifs between rhesus and humans. Common sequences were also found within the colon and vagina of the same animal, and within the peripheral blood and intestine of different unrelated animals. These results validate rhesus macaques as a useful model for γδ TCR repertoire and homing studies. Moreover, they provide evidence that the concept of limited but overlapping Vγ TCR repertoire between unrelated individuals can be extended including the mucosa of the digestive and reproductive tract.
Induction of Hyporesponsiveness and Impaired T Lymphocyte Activation by the CD31 Receptor:Ligand Pathway in T Cells
Authors: Prager Elisabeth , Staffler Günther , Majdic Otto , Säemann Marcus D. , Godár Samuel , Zlabinger Gerhard J. , Stockinger Hannes
Published: April 2014

CD31 is a member of the Ig superfamily expressed on various cell types of the vasculature, including a certain subpopulation of T lymphocytes. Previous reports suggest that interaction of CD31 with its heterophilic ligand on T cells (T cell CD31 ligand) plays a regulatory role in T lymphocyte activation. Here we demonstrate that a soluble rCD31-receptorglobulin (CD31Rg) specifically down-regulated the proliferation of human peripheral blood CD31− T lymphocytes stimulated via CD3 and CD28 mAbs. Notably, engagement of the T cell CD31 ligand by CD31Rg during primary stimulation also induced a prolonged unresponsive state in T cells. Retroviral transduction of CD31 into CD31− Th clones resulted in a significant inhibition of their proliferative capacity. When cocultured with purified CD31− T lymphocytes, irradiated CD31-transduced Th clones counterregulated the CD3/CD28-mediated activation of these cells. Furthermore, primary stimulation in the presence of CD31-transduced Th clones induced a comparable state of hyporesponsiveness in the T cell responders as the soluble CD31Rg. Thus, by counterregulating the activation of cognate T lymphocytes, CD31-expressing T cells might contribute to the establishment and maintenance of peripheral tolerance.
Protection Against Diabetes and Improved NK/NKT Cell Performance in NOD.NK1.1 Mice Congenic at the NK Complex
Authors: Carnaud Claude , Gombert Jean-Marc , Donnars Olivier , Garchon Henri-Jean , Herbelin André
Published: April 2014

The NK1.1 cell surface receptor, which belongs to the NKR-P1 gene cluster, has been bred onto nonobese diabetic (NOD) mice for two purposes. The first was to tag NK and NKT cells for easier experimental identification of those subsets and better analysis of their implication in type 1 diabetes. The second was to produce a congenic strain carrying Idd6, a susceptibility locus that has been repeatedly mapped in the vicinity of the NKR-P1 gene cluster and the NK complex, to explore the impact of this locus upon autoimmune diabetes. NOD.NK1.1 mice express the NK1.1 marker selectively on the surface of their NK and NKT cell subsets. In addition, the mice manifest reduced disease incidence and improved NK and NKT cell performance, as compared with wild-type NOD mice. The association of those two features in the same congenic strain constitutes a strong argument in favor of Idd6 being associated to the NK complex. This could explain at the same time the multiple alterations of innate immunity reported in NOD mice and the fact that disease onset can be readily modified by boosting the innate immune system of the mouse.
Microbial Lipopeptides Stimulate Dendritic Cell Maturation Via Toll-Like Receptor 2
Authors: Hertz Cheryl J. , Kiertscher Sylvia M. , Godowski Paul J. , Bouis Deborah A. , Norgard Michael V. , Roth Michael D. , Modlin Robert L.
Published: April 2014

The ability of dendritic cells (DC) to initiate immune responses in naive T cells is dependent upon a maturation process that allows the cells to develop their potent Ag-presenting capacity. Although immature DC can be derived in vitro by treatment of peripheral blood monocytes with GM-CSF and IL-4, additional signals such as those provided by TNF-α, CD40 ligand, or LPS are required for complete maturation and maximum APC function. Because we recently found that microbial lipoproteins can activate monocytes and DC through Toll-like receptor (TLR) 2, we also investigated whether lipoproteins can drive DC maturation. Immature DC were cultured with or without lipoproteins and were monitored for expression of cell surface markers indicative of maturation. Stimulation with lipopeptides increased expression of CD83, MHC class II, CD80, CD86, CD54, and CD58, and decreased CD32 expression and endocytic activity; these lipopeptide-matured DC also displayed enhanced T cell stimulatory capacity in MLR, as measured by T cell proliferation and IFN-γ secretion. The lipid moiety of the lipopeptide was found to be essential for induction of maturation. Preincubation of maturing DC with an anti-TLR2 blocking Ab before addition of lipopeptide blocked the phenotypic and functional changes associated with DC maturation. These results demonstrate that lipopeptides can stimulate DC maturation via TLR2, providing a mechanism by which products of bacteria can participate in the initiation of an immune response.