bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of T Cell Responses to the RgpA-Kgp Proteinase-Adhesin Complexes of Porphyromonas gingivalis in BALB/c Mice
Authors: Tam Vivian , O'Brien-Simpson Neil M. , Pathirana Rishi D. , Frazer Leanne T. , Reynolds Eric C. 
Published: April 2014

Abstract
Porphyromonas gingivalis is a Gram-negative bacterium strongly associated with chronic periodontitis, an inflammatory oral disease. A major virulence factor common to all characterized strains of P. gingivalis is the RgpA-Kgp proteinase-adhesin complexes (RgpA-Kgp complexes). In this study, we investigated T cell proliferative and cytokine responses to the RgpA-Kgp complexes and identified T cell epitopes in BALB/c mice utilizing Pepscan methodology. T cell proliferative responses were found to be predominantly directed toward the proteinase catalytic domains. Eleven T cell epitopes were identified using RgpA-Kgp-primed lymph node T cells (IL-4 dominant) and 21 using an RgpA-Kgp-specific T cell line (IFN-γ dominant), with 5 T cell epitopes, including the immunodominant epitope peptide 22, common to both T cell populations. Peptide 22 (439ANYTAHGSETAWADP453) from the Kgp proteinase catalytic domain induced a Th2 cytokine response in mice, and peptide 22-primed T cells had a Th2 cytokine profile when stimulated with the RgpA-Kgp complexes. Truncation and alanine scanning of peptide 22 identified the minimum epitope (442TAHGSETAWA451), and residues His444, Glu447, and Trp450 as critical for T cell proliferation. With a view to vaccine development, peptide 22 was incorporated into a synthetic peptide polymer. Peptide 22 polymer induced strong T cell proliferation and crossreactivity to native RgpA-Kgp complexes. In conclusion, we have identified a major T cell epitope of P. gingivalis and established that antigenicity of the T cell epitope is retained when delivered as a peptide polymer. The strategies employed here may have potential in the development of a synthetic peptide vaccine for P. gingivalis.
Essential Involvement of CX3CR1-Mediated Signals in the Bactericidal Host Defense during Septic Peritonitis
Authors: Ishida Yuko , Hayashi Takahito , Goto Takatsugu , Kimura Akihiko , Akimoto Shigeru , Mukaida Naofumi , Kondo Toshikazu 
Published: April 2014

Abstract
Cecal ligation and puncture (CLP) caused septic peritonitis in wild-type (WT) mice, with ∼33% mortality within 7 days after the procedure. Concomitantly, the protein level of intraperitoneal CX3CL1/fractalkine was increased, with infiltration by CX3CR1-expressing macrophages into the peritoneum. CLP induced 75% mortality in CX3CR1-deficient (CX3CR1−/−) mice, which, however, exhibited a similar degree of intraperitoneal leukocyte infiltration as WT mice. Despite this, CX3CR1−/− mice exhibited impairment in intraperitoneal bacterial clearance, together with a reduction in the expression of intraperitoneal inducible NO synthase (iNOS) and bactericidal proinflammatory cytokines, including IL-1β, TNF-α, IFN-γ, and IL-12, compared with WT mice. Bactericidal ability of peritoneal phagocytes such as neutrophils and macrophages was consistently attenuated in CX3CR1−/− mice compared with WT mice. Moreover, when WT macrophages were stimulated in vitro with CX3CL1, their bactericidal activity was augmented in a dose-dependent manner, with enhanced iNOS gene expression and subsequent NO generation. Furthermore, CX3CL1 enhanced the gene expression of IL-1β, TNF-α, IFN-γ, and IL-12 by WT macrophages with NF-κB activation. Thus, CX3CL1-CX3CR1 interaction is crucial for optimal host defense against bacterial infection by activating bacterial killing functions of phagocytes, and by augmenting iNOS-mediated NO generation and bactericidal proinflammatory cytokine production mainly through the NF-κB signal pathway, with few effects on macrophage infiltration.
Liver X Receptor Agonists Increase Airway Reactivity in a Model of Asthma via Increasing Airway Smooth Muscle Growth
Authors: Birrell Mark A. , De Alba Jorge , Catley Matthew C. , Hardaker Elizabeth , Wong Sissie , Collins Michael , Clarke Deborah L. , Farrow Stuart N. , Willson Timothy M. , Collins Jon L. , Belvisi Maria G. 
Published: April 2014

Abstract
The liver X receptors (LXRα/β) are orphan nuclear receptors that are expressed in a large number of cell types and have been shown to have anti-inflammatory properties. Nuclear receptors have previously proved to be amenable targets for small molecular mass pharmacological agents in asthma, and so the effect of an LXR ligand was assessed in models of allergic airway inflammation. LXR agonist, GW 3965, was profiled in rat and mouse models of allergic asthma. In the Brown Norway rats, GW 3965 (3–30 mg/kg) was unable to reduce the bronchoalveolar lavage eosinophilia associated with this model and had no impact on inflammatory biomarkers (eotaxin and IL-1β). The compound did significantly stimulate ABCA-1 (ATP-binding cassette A1) mRNA expression, indicating that there was adequate exposure/LXR activation. In the mouse model, the LXR ligand surprisingly increased airway reactivity, an effect that was apparent in both the Ag and nonchallenged groups. This increase was not associated with a change in lung tissue inflammation or number of mucus-containing cells. There was, however, a marked increase in airway smooth muscle thickness in both treated groups. We demonstrated an increase in contractile response to exogenous methacholine in isolated airways taken from LXR agonist-treated animals compared with the relevant control tissue. We corroborated these findings in a human system by demonstrating increased proliferation of cultured airway smooth muscle. This phenomenon, if evidenced in man, would indicate that LXR ligands may directly increase airway reactivity, which could be detrimental, especially in patients with existing respiratory disease and with already compromised lung function.
TLR-2 and IL-17A in Chitin-Induced Macrophage Activation and Acute Inflammation
Authors: Da Silva Carla A. , Hartl Dominik , Liu Wei , Lee Chun G. , Elias Jack A. 
Published: April 2014

Abstract
Chitin is a ubiquitous polysaccharide in fungi, insects, and parasites. To test the hypothesis that chitin is an important immune modulator, we characterized the ability of chitin fragments to regulate murine macrophage cytokine production in vitro and induce acute inflammation in vivo. In this study, we show that chitin is a size-dependent stimulator of macrophage IL-17A production and IL-17AR expression and demonstrate that these responses are TLR-2 and MyD88-dependent. We further demonstrate that IL-17A pathway activation is an essential event in the stimulation of some but not all chitin-stimulated cytokines and that chitin uses a TLR-2, MyD88-, and IL-17A-dependent mechanism(s) to induce acute inflammation. These studies demonstrate that chitin is a size-dependent pathogen-associated molecular pattern that activates TLR-2 and MyD88 in a novel IL-17A/IL-17AR-based innate immunity pathway.
Hydrogen Sulfide Augments Neutrophil Migration through Enhancement of Adhesion Molecule Expression and Prevention of CXCR2 Internalization: Role of ATP-Sensitive Potassium Channels
Authors: Dal-Secco Daniela , Cunha Thiago M. , Freitas Andressa , Alves-Filho José Carlos , Souto Fabrício O. , Fukada Sandra Y. , Grespan Renata , Alencar Nylane M. N. , Neto Alberto F. , Rossi Marcos A. , Ferreira Sérgio H. , Hothersall John S. , Cunha Fernando Q. 
Published: April 2014

Abstract
In this study, we have addressed the role of H2S in modulating neutrophil migration in either innate (LPS-challenged naive mice) or adaptive (methylated BSA (mBSA)-challenged immunized mice) immune responses. Treatment of mice with H2S synthesis inhibitors, dl-propargylglycine (PAG) or β-cyanoalanine, reduced neutrophil migration induced by LPS or methylated BSA (mBSA) into the peritoneal cavity and by mBSA into the femur/tibial joint of immunized mice. This effect was associated with decreased leukocyte rolling, adhesion, and P-selectin and ICAM-1 expression on endothelium. Predictably, treatment of animals with the H2S donors, NaHS or Lawesson’s reagent, enhanced these parameters. Moreover, the NaHS enhancement of neutrophil migration was not observed in ICAM-1-deficient mice. Neither PAG nor NaHS treatment changed LPS-induced CD18 expression on neutrophils, nor did the LPS- and mBSA-induced release of neutrophil chemoattractant mediators TNF-α, keratinocyte-derived chemokine, and LTB4. Furthermore, in vitro MIP-2-induced neutrophil chemotaxis was inhibited by PAG and enhanced by NaHS treatments. Accordingly, MIP-2-induced CXCR2 internalization was enhanced by PAG and inhibited by NaHS treatments. Moreover, NaHS prevented MIP-2-induced CXCR2 desensitization. The PAG and NaHS effects correlated, respectively, with the enhancement and inhibition of MIP-2-induced G protein-coupled receptor kinase 2 expression. The effects of NaHS on neutrophil migration both in vivo and in vitro, together with CXCR2 internalization and G protein-coupled receptor kinase 2 expression were prevented by the ATP-sensitive potassium (KATP+) channel blocker, glybenclamide. Conversely, diazoxide, a KATP+ channel opener, increased neutrophil migration in vivo. Together, our data suggest that during the inflammatory response, H2S augments neutrophil adhesion and locomotion, by a mechanism dependent on KATP+ channels.
Endogenous Hydrogen Sulfide Regulates Inflammatory Response by Activating the ERK Pathway in Polymicrobial Sepsis
Authors: Zhang Huili , Moochhala Shabbir M. , Bhatia Madhav 
Published: April 2014

Abstract
Hydrogen sulfide (H2S) up-regulates inflammatory response in several inflammatory diseases. However, to date, little is known about the molecular mechanism by which H2S provokes the inflammatory response in sepsis. Thus, the aim of this study was to investigate the signaling pathway underlying the proinflammatory role of H2S in cecal ligation and puncture (CLP)-induced sepsis. Male Swiss mice were subjected to CLP and treated with dl-propargylglycine (PAG; 50 mg/kg i.p., an inhibitor of H2S formation), NaHS (10 mg/kg, i.p., an H2S donor), or saline. PAG was administered 1 h before CLP, whereas NaHS was given at the time of CLP. CLP-induced sepsis resulted in a time-dependent increase in the synthesis of endogenous H2S. Maximum phosphorylation of ERK1/2 and degradation of IκBα in lung and liver were observed 4 h after CLP. Inhibition of H2S formation by PAG significantly reduced the phosphorylation of ERK1/2 in lung and liver 4 h after CLP, coupled with decreased degradation of IκBα and activation of NF-κB. In contrast, injection of NaHS significantly enhanced the activation of ERK1/2 in lung and liver, therefore leading to a further rise in tissue NF-κB activity. As a result, pretreatment with PAG significantly reduced the production of cytokines and chemokines in sepsis, whereas exogenous H2S greatly increased it. In addition, pretreatment with PD98059, an inhibitor of ERK kinase (MEK-1), significantly prevented NaHS from aggravating systemic inflammation in sepsis. In conclusion, the present study shows for the first time that H2S may regulate systemic inflammatory response in sepsis via ERK pathway.
Cross-Tolerization between Nod1 and Nod2 Signaling Results in Reduced Refractoriness to Bacterial Infection in Nod2-Deficient Macrophages
Authors: Kim Yun-Gi , Park Jong-Hwan , Daignault Stephanie , Fukase Koichi , Núñez Gabriel 
Published: April 2014

Abstract
Nod2 is an intracellular innate immune receptor that plays a role in host defense and susceptibility to inflammatory disease. We show in this study that macrophages rendered refractory to TLR4 and Nod2 signaling by exposure to LPS and muramyl dipeptide (MDP) exhibit impaired TNF-α and IL-6 production in response to pathogenic Listeria monocytogenes and Yersinia pseudotuberculosis as well as commensal bacteria including Escherichia coli and Bacteroides fragilis. Surprisingly, Nod2 deficiency was associated with impaired tolerization in response to pathogenic and commensal bacteria. Mechanistically, reduced tolerization of Nod2-null macrophages was mediated by recognition of bacteria through Nod1 because it was abolished in macrophages deficient in Nod1 and Nod2. Consistently, Nod2-null macrophages tolerant to LPS and MDP showed enhanced production of TNF-α and IL-6 as well as increased NF-κB and MAPK activation in response to the dipeptide KF1B, the Nod1 agonist. Furthermore, reduced tolerization of Nod2-deficient macrophages in response to bacteria was abolished when mutant macrophages were also rendered tolerant to the Nod1 ligand. Finally, MDP stimulation induced refractoriness not only to MDP, but also to iE-DAP stimulation, providing a mechanism to explain the reduced tolerization of Nod2-deficient macrophages infected with bacteria. These results demonstrate that cross-tolerization between Nod1 and Nod2 leads to increase recognition of both pathogenic and commensal bacteria in Nod2-deficient macrophages pre-exposed to microbial ligands.
Evidence for an Association between Thyroid-Stimulating Hormone and Insulin-Like Growth Factor 1 Receptors: A Tale of Two Antigens Implicated in Graves’ Disease
Authors: Tsui Shanli , Naik Vibha , Hoa Neil , Hwang Catherine J. , Afifiyan Nikoo F. , Sinha Hikim Amiya , Gianoukakis Andrew G. , Douglas Raymond S. , Smith Terry J. 
Published: April 2014

Abstract
Thyroid-stimulating hormone receptor (TSHR) plays a central role in regulating thyroid function and is targeted by IgGs in Graves’ disease (GD-IgG). Whether TSHR is involved in the pathogenesis of thyroid-associated ophthalmopathy (TAO), the orbital manifestation of GD, remains uncertain. TSHR signaling overlaps with that of insulin-like grow factor 1 receptor (IGF-1R). GD-IgG can activate fibroblasts derived from donors with GD to synthesize T cell chemoattractants and hyaluronan, actions mediated through IGF-1R. In this study, we compare levels of IGF-1R and TSHR on the surfaces of TAO and control orbital fibroblasts and thyrocytes and explore the physical and functional relationship between the two receptors. TSHR levels are 11-fold higher on thyrocytes than on TAO or control fibroblasts. In contrast, IGF-1R levels are 3-fold higher on TAO vs control fibroblasts. In pull-down studies using fibroblasts, thyrocytes, and thyroid tissue, Abs directed specifically against either IGF-1Rβ or TSHR bring both proteins out of solution. Moreover, IGF-1Rβ and TSHR colocalize to the perinuclear and cytoplasmic compartments in fibroblasts and thyrocytes by confocal microscopy. Examination of orbital tissue from patients with TAO reveals similar colocalization to cell membranes. Treatment of primary thyrocytes with recombinant human TSH results in rapid ERK phosphorylation which can be blocked by an IGF-1R-blocking mAb. Our findings suggest that IGF-1R might mediate some TSH-provoked signaling. Furthermore, they indicate that TSHR levels on orbital fibroblasts are considerably lower than those on thyrocytes and that this receptor associates with IGF-1R in situ and together may comprise a functional complex in thyroid and orbital tissue.
Cutting Edge: CD25+ Regulatory T Cells Prevent Expansion and Induce Apoptosis of B Cells Specific for Tissue Autoantigens
Authors: Ludwig-Portugall Isis , Hamilton-Williams Emma E. , Gottschalk Catherine , Kurts Christian 
Published: April 2014

Abstract
To study the role of CD25+ regulatory T cells (Tregs) in peripheral B cell tolerance, we generated transgenic rat insulin promoter RIP-OVA/HEL mice expressing the model Ags OVA and HEL in pancreatic islet β cells (where RIP is rat insulin promoter and HEL is hen egg lysozyme). Adoptively transferred transgenic OVA-specific CD4+ and CD8+ T cells proliferated only in the autoantigen-draining pancreatic lymph node (PLN), demonstrating pancreas-specific Ag expression. Transferred HEL-specific transgenic B cells (IgHEL cells) disappeared within 3 wk from transgenic but not from nontransgenic mice immunized with autoantigen. Depletion of CD25+ FoxP3+ cells completely restored IgHEL cell numbers. Treg exerted an analogous suppressive effect on endogenous HEL-specific autoreactive B cells. Tregs acted by inhibiting the proliferation of IgHEL cells in the spleen and PLN and by systemic induction of their apoptosis. Furthermore, they reduced BCR and MHC II surface expression on IgHEL cells in the PLN. These findings demonstrate that autoreactive B cells specific for a nonlymphoid tissue autoantigen are controlled by Tregs.
Disruption of the Transcription Factor Nrf2 Promotes Pro-Oxidative Dendritic Cells That Stimulate Th2-Like Immunoresponsiveness upon Activation by Ambient Particulate Matter
Authors: Williams Marc A. , Rangasamy Tirumalai , Bauer Stephen M. , Killedar Smruti , Karp Matthew , Kensler Thomas W. , Yamamoto Masayuki , Breysse Patrick , Biswal Shyam , Georas Steve N. 
Published: April 2014

Abstract
Oxidative stress is important in dendritic cell (DC) activation. Environmental particulate matter (PM) directs pro-oxidant activities that may alter DC function. Nuclear erythroid 2 p45-related factor 2 (Nrf2) is a redox-sensitive transcription factor that regulates expression of antioxidant and detoxification genes. Oxidative stress and defective antioxidant responses may contribute to the exacerbations of asthma. We hypothesized that PM would impart differential responses by Nrf2 wild-type DCs as compared with Nrf2−/− DCs. We found that the deletion of Nrf2 affected important constitutive functions of both bone marrow-derived and highly purified myeloid lung DCs such as the secretion of inflammatory cytokines and their ability to take up exogenous Ag. Stimulation of Nrf2−/− DCs with PM augmented oxidative stress and cytokine production as compared with resting or Nrf2+/+ DCs. This was associated with the enhanced induction of Nrf2-regulated antioxidant genes. In contrast to Nrf2+/+ DCs, coincubation of Nrf2−/− DCs with PM and the antioxidant N-acetyl cysteine attenuated PM-induced up-regulation of CD80 and CD86. Our studies indicate a previously underappreciated role of Nrf2 in innate immunity and suggest that deficiency in Nrf2-dependent pathways may be involved in susceptibility to the adverse health effects of air pollution in part by promoting Th2 cytokine responses in the absence of functional Nrf2. Moreover, our studies have uncovered a hierarchal response to oxidative stress in terms of costimulatory molecule expression and cytokine secretion in DCs and suggest an important role of heightened oxidative stress in proallergic Th2-mediated immune responses orchestrated by DCs.
Differential Susceptibility of Allogeneic Targets to Indirect CD4 Immunity Generates Split Tolerance
Authors: Chan William F. N. , Razavy Haide , Anderson Colin C. 
Published: April 2014

Abstract
CD4 T cells frequently help to activate CD8 T and B cells that effect transplant rejection. However, CD4 T cells alone can reject transplants, either directly or indirectly. The relative effectiveness of indirect CD4 immunity in rejecting different types of allogeneic grafts is unknown. To address this, we used a TCR transgenic mouse model in which indirect CD4 alloimmunity alone can be studied. We challenged transgenic recipients with hematopoietic cells and shortly thereafter skin transplants that could only be rejected indirectly, and observed Ag-specific indirect donor B cell and skin rejection, but not T cell elimination, reflecting a state of split tolerance. Deficiency of indirect CD4 alloimmunity in donor T cell rejection was also apparent when acute indirect rejection of donor islets occurred despite generation and maintenance of mixed T cell chimerism, due to migration of the few passenger T cells into recipient circulation. Although passenger lymphocytes delayed indirect islet rejection, they enhanced rejection by a full repertoire capable of both direct and indirect reactivity. Interestingly, the persistence of chimerism was associated with the eventual development of tolerance, as demonstrated by acceptance of donor skin grafts given late to hematopoietic cell recipients, and hyporesponsiveness of transgenic T cells from islet recipients in vitro. Mechanistically, tolerance was recessive and associated with progressive down-regulation of CD4. Collectively, our data indicate that indirect CD4 immunity is not equally destructive toward different types of allogeneic grafts, the deficiency of which generates split tolerance. The futility of these responses can convert immunity into tolerance.
Proinflammatory S100 Proteins Regulate the Accumulation of Myeloid-Derived Suppressor Cells
Authors: Sinha Pratima , Okoro Chinonyerem , Foell Dirk , Freeze Hudson H. , Ostrand-Rosenberg Suzanne , Srikrishna Geetha 
Published: April 2014

Abstract
Chronic inflammation is a complex process that promotes carcinogenesis and tumor progression; however, the mechanisms by which specific inflammatory mediators contribute to tumor growth remain unclear. We and others recently demonstrated that the inflammatory mediators IL-1β, IL-6, and PGE2 induce accumulation of myeloid-derived suppressor cells (MDSC) in tumor-bearing individuals. MDSC impair tumor immunity and thereby facilitate carcinogenesis and tumor progression by inhibiting T and NK cell activation, and by polarizing immunity toward a tumor-promoting type 2 phenotype. We now show that this population of immature myeloid cells induced by a given tumor share a common phenotype regardless of their in vivo location (bone marrow, spleen, blood, or tumor site), and that Gr1highCD11bhighF4/80−CD80+IL4Rα+/−Arginase+ MDSC are induced by the proinflammatory proteins S100A8/A9. S100A8/A9 proteins bind to carboxylated N-glycans expressed on the receptor for advanced glycation end-products and other cell surface glycoprotein receptors on MDSC, signal through the NF-κB pathway, and promote MDSC migration. MDSC also synthesize and secrete S100A8/A9 proteins that accumulate in the serum of tumor-bearing mice, and in vivo blocking of S100A8/A9 binding to MDSC using an anti-carboxylated glycan Ab reduces MDSC levels in blood and secondary lymphoid organs in mice with metastatic disease. Therefore, the S100 family of inflammatory mediators serves as an autocrine feedback loop that sustains accumulation of MDSC. Since S100A8/A9 activation of MDSC is through the NF-κB signaling pathway, drugs that target this pathway may reduce MDSC levels and be useful therapeutic agents in conjunction with active immunotherapy in cancer patients.
Protein Kinase C-θ Is Required for Efficient Positive Selection
Authors: Morley Sharon Celeste , Weber K. Scott , Kao Henry , Allen Paul M. 
Published: April 2014

Abstract
Protein kinase C-θ (PKCθ) is critical for TCR-initiated signaling in mature T cells, but initial reports found no requirement for PKCθ in thymocyte development. Thymocytes and peripheral T cells utilize many of the same signaling components and, given the significant role of PKCθ in peripheral T cells, it was surprising that it was not involved at all in TCR signaling in thymocytes. We decided to re-evaluate the role of PKCθ in thymocyte development using the well-characterized class II-restricted n3.L2 TCR-transgenic TCR model. Analysis of n3.L2 PKCθ−/− mice revealed a defect in thymocyte-positive selection, resulting in a 50% reduction in the generation of n3.L2 CD4 single-positive thymocytes and n3.L2 CD4 mature T cells. Competition between n3.L2 WT and n3.L2 PKCθ−/− thymocytes in bone marrow chimeras revealed a more dramatic defect, with a &gt;80% reduction in generation of n3.L2 CD4 single-positive thymocytes derived from PKCθ−/− mice. Inefficient positive selection of n3.L2 PKCθ−/− CD4 single-positive cells resulted from “weaker” signaling through the TCR and correlated with diminished ERK activation. The defect in positive selection was not complete in the PKCθ−/− mice, most likely accounted for by compensation by other PKC isoforms not evident in peripheral cells. Similar decreased positive selection of both CD4 and CD8 single-positive thymocytes was also seen in nontransgenic PKCθ−/− mice. These findings now place PKCθ as a key signaling molecule in the positive selection of thymocytes as well as in the activation of mature T cells.