bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transglutaminase Type II Is a Key Element in the Regulation of the Anti-Inflammatory Response Elicited by Apoptotic Cell Engulfment
Authors: Falasca Laura , Iadevaia Valentina , Ciccosanti Fabiola , Melino Gennaro , Serafino Annalucia , Piacentini Mauro 
Published: April 2014

Abstract
A key feature of the macrophage-dependent clearance of apoptotic cells is the down-regulation of proinflammatory cytokines. Deficiency in the phagocytosis of apoptotic cells is often associated with the development of inflammatory reactions, resulting in chronic inflammatory and autoimmune diseases. The molecular mechanisms that regulate the engulfment process and particularly the immunomodulatory factors involved are still largely unknown in mammals. We have previously reported that the ablation of transglutaminase type II (TG2) in mice results in the defective clearance of apoptotic cells associated with the development of splenomegaly, autoantibodies, and glomerulonephritis. In this study we have investigated the mechanisms at the basis of the development of inflammation/autoimmunity associated with the defective clearance of apoptotic cells characterizing TG2 knockout mice. To this aim we compared the macrophage response to apoptotic cell exposure in wild-type vs TG2-null mice. We demonstrated that the lack of TG2 results in an impaired capacity of macrophages to engulf, but not to bind, apoptotic cells, which is paralleled by an abnormal inflammatory response both in vivo and in vitro. We have identified a differential response in the release of several cytokines in TG2−/− vs wild-type mice. Particularly relevant is the finding that both TGF-β and IL-12 regulations were significantly altered in the absence of TG2. These results help explain the autoimmune phenotype developed by these mice and suggest that TG2 is a key regulatory element of the anti-inflammatory features of apoptosis.
Proteolytic Activation of Alternative CCR1 Ligands in Inflammation
Authors: Berahovich Robert D. , Miao Zhenhua , Wang Yu , Premack Brett , Howard Maureen C. , Schall Thomas J. 
Published: April 2014

Abstract
Although chemokines CCL3/MIP-1α and CCL5/RANTES are considered to be primary CCR1 ligands in inflammatory responses, alternative CCR1 ligands have also been described. Indeed, four such chemokines, CCL6/C10/MIP-related protein-1, CCL9/MIP-1γ/MIP-related protein-2, CCL15/MIP-1δ/hemofiltrate CC chemokine-2/leukotactin-1, and CCL23/CKβ8/myeloid progenitor inhibitory factor-1, are unique in possessing a separately encoded N-terminal domain of 16–20 residues and two additional precisely positioned cysteines that form a third disulfide bridge. In vitro, these four chemokines are weak CCR1 agonists, but potency can be increased up to 1000-fold by engineered or expression-associated N-terminal truncations. We examined the ability of proinflammatory proteases, human cell supernatants, or physiological fluids to perform N-terminal truncations of these chemokines and thereby activate their functions. Remarkably, most of the proteases and fluids removed the N-terminal domains from all four chemokines, but were relatively unable to cleave the truncated forms further. The truncated chemokines exhibited up to 1000-fold increases in CCR1-mediated signaling and chemotaxis assays in vitro. In addition, N-terminally truncated CCL15/MIP-1δ and CCL23/CKβ8, but not CCL3/MIP-1α or CCL5/RANTES, were detected at relatively high levels in synovial fluids from rheumatoid arthritis patients. These data suggest that alternative CCR1 ligands are converted into potent chemoattractants by proteases released during inflammatory responses in vivo.
Effects of Leflunomide on Hyaluronan Synthases (HAS): NF-κB-Independent Suppression of IL-1-Induced HAS1 Transcription by Leflunomide
Authors: Stuhlmeier Karl M. 
Published: April 2014

Abstract
Despite evidence that points to unfettered hyaluronic acid (HA) production as a culprit in the progression of rheumatic disorders, little is known about differences in regulation and biological functions of the three hyaluronan synthase (HAS) genes. Testing the effects of drugs with proven anti-inflammatory effects could help to clarify biological functions of these genes. In this study, we demonstrate that leflunomide suppresses HA release in fibroblast-like synoviocytes (FLS) in a dose-dependent manner. We further demonstrate that leflunomide suppresses HA synthase activity, as determined by 14C-glucuronic acid incorporation assays. Additional experiments revealed that in FLS, leflunomide specifically blocked the induction of HAS1. HAS2 and HAS3, genes that are, in contrast to HAS1, constitutively expressed in FLS, are not significantly affected. Leflunomide can function as a NF-κB inhibitor. However, EMSA experiments demonstrate that at the concentrations used, leflunomide neither interferes with IL-1β- nor with PMA-induced NF-κB translocation. Furthermore, reconstituting the pyrimidine synthase pathway did not lead to the restoration of IL-1β-induced HAS1 activation. More importantly, two tyrosine kinase inhibitors mimicked the effect of leflunomide in that both blocked IL-1β-induced HAS1 activation without affecting HAS2 or HAS3. These data point at HAS1 activation as the possible cause for unfettered HA production in rheumatoid arthritis and might explain, at least in part, the beneficial effects of leflunomide treatment. These findings also support the concept that IL-1β-induced HAS1 activation depends on the activation of tyrosine kinases, and indicate that leflunomide blocks HA release by suppressing tyrosine kinases rather than through inhibition of NF-κB translocation.
Identification of a Novel Blocker of IκBα Kinase That Enhances Cellular Apoptosis and Inhibits Cellular Invasion through Suppression of NF-κB-Regulated Gene Products
Authors: Ichikawa Haruyo , Takada Yasunari , Murakami Akira , Aggarwal Bharat B. 
Published: April 2014

Abstract
1′-Acetoxychavicol acetate (ACA), extracted from rhizomes of the commonly used ethno-medicinal plant Languas galanga, has been found to suppress chemical- and virus-induced tumor initiation and promotion through a poorly understood mechanism. Because several genes that regulate cellular proliferation, carcinogenesis, metastasis, and survival are regulated by activation of the transcription factor NF-κB, we postulated that ACA might mediate its activity through modulation of NF-κB activation. For this report, we investigated the effect of ACA on NF-κB and NF-κB-regulated gene expression activated by various carcinogens. We found that ACA suppressed NF-κB activation induced by a wide variety of inflammatory and carcinogenic agents, including TNF, IL-1β, PMA, LPS, H2O2, doxorubicin, and cigarette smoke condensate. Suppression was not cell type specific, because both inducible and constitutive NF-κB activations were blocked by ACA. ACA did not interfere with the binding of NF-κB to the DNA, but, rather, inhibited IκBα kinase activation, IκBα phosphorylation, IκBα degradation, p65 phosphorylation, and subsequent p65 nuclear translocation. ACA also inhibited NF-κB-dependent reporter gene expression activated by TNF, TNFR1, TNFR-associated death domain protein, TNFR-associated factor-2, and IκBα kinase, but not that activated by p65. Consequently, ACA suppressed the expression of TNF-induced NF-κB-regulated proliferative (e.g., cyclin D1 and c-Myc), antiapoptotic (survivin, inhibitor of apoptosis protein-1 (IAP1), IAP2, X-chromosome-linked IAP, Bcl-2, Bcl-xL, Bfl-1/A1, and FLIP), and metastatic (cyclooxygenase-2, ICAM-1, vascular endothelial growth factor, and matrix metalloprotease-9) gene products. ACA also enhanced the apoptosis induced by TNF and chemotherapeutic agents and suppressed invasion. Overall, our results indicate that ACA inhibits activation of NF-κB and NF-κB-regulated gene expression, which may explain the ability of ACA to enhance apoptosis and inhibit invasion.
Cross Talk between MyD88 and Focal Adhesion Kinase Pathways
Authors: Zeisel Mirjam B. , Druet Vanessa A. , Sibilia Jean , Klein Jean-Paul , Quesniaux Valérie , Wachsmann Dominique 
Published: April 2014

Abstract
Focal adhesion kinase (FAK) is a nonreceptor protein tyrosine kinase involved in signaling downstream of integrins, linking bacterial detection, cell entry, and initiation of proinflammatory response through MAPKs and NF-κB activation. In this study, using protein I/II from Streptococcus mutans as a model activator of FAK, we investigated the potential link between FAK and TLR pathways. Using macrophages from TLR- or MyD88-deficient mice, we report that MyD88 plays a major role in FAK-dependent protein I/II-induced cytokine release. However, response to protein I/II stimulation was independent of TLR4, TLR2, and TLR6. The data suggest that there is a cross talk between FAK and MyD88 signaling pathways. Moreover, MyD88-dependent, LPS-induced IL-6 secretion by human and murine fibroblasts required the presence of FAK, confirming that MyD88 and FAK pathways are interlinked.
Tolerogenic Semimature Dendritic Cells Suppress Experimental Autoimmune Thyroiditis by Activation of Thyroglobulin-Specific CD4+CD25+ T Cells
Authors: Verginis Panayotis , Li Haiyan S. , Carayanniotis George 
Published: April 2014

Abstract
Ex vivo treatment of bone marrow-derived dendritic cells (DCs) with TNF-α has been previously shown to induce partial maturation of DCs that are able to suppress autoimmunity. In this study, we demonstrate that i.v. administration of TNF-α-treated, semimature DCs pulsed with thyrogloblin (Tg), but not with OVA Ag, inhibits the subsequent development of Tg-induced experimental autoimmune thyroiditis (EAT) in CBA/J mice. This protocol activates CD4+CD25+ T cells in vivo, which secrete IL-10 upon specific recognition of Tg in vitro and express regulatory T cell (Treg)-associated markers such as glucocorticoid-induced TNFR, CTLA-4, and Foxp3. These CD4+CD25+ Treg cells suppressed the proliferation and cytokine release of Tg-specific, CD4+CD25− effector cells in vitro, in an IL-10-independent, cell contact-dependent manner. Prior adoptive transfer of the same CD4+CD25+ Treg cells into CBA/J hosts suppressed Tg-induced EAT. These results demonstrate that the tolerogenic potential of Tg-pulsed, semimature DCs in EAT is likely to be mediated through the selective activation of Tg-specific CD4+CD25+ Treg cells and provide new insights for the study of Ag-specific immunoregulation of autoimmune diseases.
Cutting Edge: IL-10-Independent STAT3 Activation byToxoplasma gondiiMediates Suppression of IL-12 and TNF-α in Host Macrophages
Authors: Butcher Barbara A. , Kim Leesun , Panopoulos Athanasia D. , Watowich Stephanie S. , Murray Peter J. , Denkers Eric Y. 
Published: April 2014

AbstractInfection of mouse macrophages by Toxoplasma gondii renders the cells resistant to proinflammatory effects of LPS triggering. In this study, we show that cell invasion is accompanied by rapid and sustained activation of host STAT3. Activation of STAT3 did not occur with soluble T. gondii extracts or heat-killed tachyzoites, demonstrating a requirement for live parasites. Parasite-induced STAT3 phosphorylation and suppression of LPS-triggered TNF-α and IL-12 was intact in IL-10-deficient macrophages, ruling out a role for this anti-inflammatory cytokine in the suppressive effects of T. gondii. Most importantly, Toxoplasma could not effectively suppress LPS-triggered TNF-α and IL-12 synthesis in STAT3-deficient macrophages. These results demonstrate that T. gondii exploits host STAT3 to prevent LPS-triggered IL-12 and TNF-α production, revealing for the first time a molecular mechanism underlying the parasite’s suppressive effect on macrophage proinflammatory cytokine production.
Cutting Edge: Signaling Lymphocytic Activation Molecule-Associated Protein Controls NKT Cell Functions
Authors: Chung Brian , Aoukaty Ala , Dutz Jan , Terhorst Cox , Tan Rusung 
Published: April 2014

AbstractX-linked lymphoproliferative disease (XLP) is a fatal immunological disorder that typically manifests following EBV infection. XLP patients exhibit a number of immune defects including abnormal T, B, and NK lymphocyte function. These defects have been attributed to mutations of Src homology 2 domain-containing gene 1A (SH2D1A), the gene encoding signaling lymphocytic activation molecule-associated protein (SAP), an intracellular adaptor molecule expressed in lymphocytes. We have observed that SAP knockout (SAPKO) mice and humans with XLP have a complete lack of CD1d-restricted NKT cells. As expected, SAPKO mice injected with the NKT cell agonist, α-galactosylceramide failed to generate NKT cell IFN-γ or IL-4. Furthermore, in contrast to wild-type littermates, SAPKO mice coinjected with OVA and α-galactosylceramide failed to mount OVA-specific CTL responses. These data suggest that an absence of NKT cells may underlie part of the immune dysregulation seen in SAPKO mice and in XLP patients.
Cutting Edge: Recent Immune Status Determines the Source of Antigens That Drive Homeostatic T Cell Expansion
Authors: Kieper William C. , Troy Amy , Burghardt J. Theodore , Ramsey Chris , Lee Joon Youb , Jiang Han-Qing , Dummer Wolfgang , Shen Hao , Cebra John J. , Surh Charles D. 
Published: April 2014

Abstract
Homeostatic proliferation of naive T cells transferred to T cell-deficient syngeneic mice is driven by low-affinity self-MHC/peptide ligands and the cytokine IL-7. In addition to homeostatic proliferation, a subset of naive T cells undergoes massive proliferation in chronically immunodeficient hosts, but not in irradiated normal hosts. Such rapid T cell proliferation occurs largely independent of homeostatic factors, because it was apparent in the absence of IL-7 and in T cell-sufficient hosts devoid of functional T cell immunity. Strikingly, immunodeficient mice raised under germfree conditions supported only slow homeostatic proliferation, but not the marked T cell proliferation observed in conventionally raised immunodeficient mice. Thus, polyclonal naive T cell expansion in T cell-deficient hosts can be driven predominantly by either self-Ags or foreign Ags depending on the host’s previous state of T cell immunocompetency.
Cutting Edge: Stat5 Mediates the IL-7-Induced Accessibility of a Representative D-Distal VH Gene
Authors: Stanton Michelle L. , Brodeur Peter H. 
Published: April 2014

Abstract
During B cell development, discrete domains within the Igh locus are activated independently for recombination. The D-distal VH genes are uniquely dependent on IL-7R signaling, which is thought to establish local chromatin accessibility through an unknown mechanism. To dissect this mechanism, we used a murine B cell line that responds to IL-7 by specifically inducing accessibility of a representative D-distal gene (A1) but not a D-proximal gene (V11). We demonstrate that IL-7-activated Stat5 is recruited rapidly to the A1 gene, with a concomitant increase in germline transcription and H4 acetylation. Furthermore, retroviral transduction of dominant negative or constitutively active Stat5 demonstrated that Stat5 activation is both necessary and sufficient for the IL-7-induced A1 germline transcription. Lastly, as with all known Stat5 target genes, A1 germline transcription requires a deacetylase activity. These results demonstrate that in response to IL-7 signaling, Stat5 is recruited to the D-distal A1 gene and induces accessibility.
Cutting Edge: Novel Role of Lipoxygenases in the Inflammatory Response: Promotion of TNF mRNA Decay by 15-Hydroperoxyeicosatetraenoic Acid in a Monocytic Cell Line
Authors: Ferrante Judith V. , Ferrante Antonio 
Published: April 2014

AbstractThe metabolism of arachidonic acid via the lipoxygenase and cyclooxygenase pathways generates metabolites that regulate the inflammatory response. Although products of lipoxygenase are classically proinflammatory, recently it has been demonstrated that lipoxins, 15-hydroperoxyeicosatetraenoic acid (15-HPETE) and 15-hydroxyeicosatetraenoic acid exhibit anti-inflammatory activity. We now demonstrate for the first time that 15-HPETE regulates the production of the proinflammatory cytokine TNF posttranscriptionally by promoting degradation of LPS-induced TNFmRNA in a human monocytic cell line, Mono Mac 6. 15-HPETE causes a significant increase in the rate of TNF but not G3PDHmRNA degradation in the presence of the transcription inhibitor, actinomycin D. The decay of TNFmRNA is accelerated 1.7-fold, and its half-life is decreased by 57%. In view of its chemical and physical properties, we propose that 15-HPETE may function by destabilizing TNFmRNA by interaction with a trans-activating protein bound to the AU-rich element of TNFmRNA.
CD4− Plasmacytoid Dendritic Cells (pDCs) Migrate in Lymph Nodes by CpG Inoculation and Represent a Potent Functional Subset of pDCs
Authors: Yang Guo-Xiang , Lian Zhe-Xiong , Kikuchi Kentaro , Liu Yong-Jun , Ansari Aftab A. , Ikehara Susumu , Gershwin M. Eric 
Published: April 2014

Abstract
We have recently identified two groups of plasmacytoid dendritic cells (pDCs) isolated from murine liver based on the expression of CD4 and other cell surface markers uniquely expressed by pDCs. Herein, we describe the identification of both CD4+ and CD4− pDCs that clearly exist in lymph nodes (LNs), spleen, liver, thymus, bone marrow, and lung. Normally, CD4+ pDCs are enriched in LNs. However, after in vivo systemic injection with bacterial CpG, a larger number of CD4− pDCs are recruited to the LNs and local inoculation by CpG drives CD4− pDCs migrating into local sentinel LNs, suggesting that CD4− pDCs are the main subpopulation migrating to the peripheral LNs. Furthermore, although both freshly isolated CD4+ pDCs and CD4− pDCs appear as an immature plasmacytoid cell and develop into a DC morphology following activation, the two subsets have strikingly different immune features, including differences in the production pattern of cytokines stimulated with CpG and in T cell activation.
Mannose-Binding Lectin-Deficient Mice Display Defective Apoptotic Cell Clearance but No Autoimmune Phenotype
Authors: Stuart Lynda M. , Takahashi Kazue , Shi Lei , Savill John , Ezekowitz R. Alan B. 
Published: April 2014

AbstractMannose-binding lectin (MBL) is a circulating serum protein that is sequestered to sites of inflammation and infection. MBL is a member of the collectin family with structural similarities to the lung collectins and functional similarities to C1q. Both MBL and C1q activate complement; C1q activates the classical pathway and MBL the lectin pathway. Here we demonstrate that MBL binds apoptotic cells in vitro and confirm a role for MBL in clearance of apoptotic cells in vivo. Despite MBL null mice demonstrating defective apoptotic cell clearance they did not develop spontaneous autoimmunity, lymphoproliferation, or germinal center expansion although increased numbers of peritoneal B1 cells were detected. These data demonstrate an important in vivo role for MBL in clearance of dying cells and adds the MBL null animals to the few animals with demonstrable in vivo apoptotic cell clearance defects. Moreover, it demonstrates that failure of apoptotic cell clearance can be dissociated from autoimmunity.
Very Low-Dose Tolerance with Nucleosomal Peptides Controls Lupus and Induces Potent Regulatory T Cell Subsets
Authors: Kang Hee-Kap , Michaels Marissa A. , Berner Beate R. , Datta Syamal K. 
Published: April 2014

AbstractWe induced very low-dose tolerance by injecting lupus prone (SWR × NZB)F1 (SNF1) mice with 1 μg nucleosomal histone peptide autoepitopes s.c. every 2 wk. The subnanomolar peptide therapy diminished autoantibody levels and prolonged life span by delaying nephritis, especially by reducing inflammatory cell reaction and infiltration in kidneys. H471–94 was the most effective autoepitope. Low-dose tolerance therapy induced CD8+, as well as CD4+CD25+ regulatory T (Treg) cell subsets containing autoantigen-specific cells. These adaptive Treg cells suppressed IFN-γ responses of pathogenic lupus T cells to nucleosomal epitopes at up to a 1:100 ratio and reduced autoantibody production up to 90–100% by inhibiting nucleosome-stimulated T cell help to nuclear autoantigen-specific B cells. Both CD4+CD25+ and CD8+ Treg cells produced and required TGF-β1 for immunosuppression, and were effective in suppressing lupus autoimmunity upon adoptive transfer in vivo. The CD4+CD25+ T cells were partially cell contact dependent, but CD8+ T cells were contact independent. Thus, low-dose tolerance with highly conserved histone autoepitopes repairs a regulatory defect in systemic lupus erythematosus by generating long-lasting, TGF-β-producing Treg cells, without causing allergic/anaphylactic reactions or generalized immunosuppression.
Protein Conformation Significantly Influences Immune Responses to Prion Protein
Authors: Khalili-Shirazi Azadeh , Quaratino Sonia , Londei Marco , Summers Linda , Tayebi Mourad , Clarke Anthony R. , Hawke Simon H. , Jackson Graham S. , Collinge John 
Published: April 2014

AbstractIn prion diseases, such as variant Creutzfeldt-Jakob disease normal cellular prion protein (PrPC), a largely α-helical structure is converted to an abnormal conformational isoform (PrPSc) that shows an increase in β-sheet content. Similarly, the recombinant form of PrPC (rα-PrP) can be converted to a conformation dominated by β-sheet (rβ-PrP) by reduction and mild acidification in vitro, a process that may mimic in vivo conversion following PrPC internalization during recycling. Despite PrPSc accumulation and prion propagation in the lymphoreticular system before detectable neuroinvasion, no Ab response to PrP has been detected, probably due to immune tolerance. To investigate how the immune system may respond to α- and β-PrP, we immunized Prnp0/0 mice that are not tolerant of PrP with rα-PrP and rβ-PrP. In this study, we show that although T cells stimulated by these differently folded conformers PrP recognize similar immunodominant epitopes (residues 111–130 and 191–210) the cytokine profile in response to rα- and rβ-PrP was different. Challenge with rα-PrP elicited a strong response of IL-5 and IL-10, whereas rβ-PrP led to an early increased production of IFN-γ. In addition, immunization with rα-PrP led to production of predominantly IgG1 isotype Ab in the sera, whereas after immunization with rβ-PrP, IgG2b was significantly produced. Thus, both humoral and cellular responses to these differently folded isoforms of the same protein are different, indicating a possible involvement of Th1 and Th2 pathway activation. These differences may be exploitable diagnostically and therapeutically for prion diseases, such as variant Creutzfeldt-Jakob disease.
Coligation of the B Cell Receptor with Complement Receptor Type 2 (CR2/CD21) Using Its Natural Ligand C3dg: Activation without Engagement of an Inhibitory Signaling Pathway
Authors: Lyubchenko Taras , Dal Porto Joe , Cambier John C. , Holers V. Michael 
Published: April 2014

AbstractC3dg is a cleavage product of the C3 component of complement that can facilitate the coligation of the complement receptor 2 (CR2/CD21) with the BCR via C3dg/Ag complexes. This interaction can greatly amplify BCR-mediated signaling events and acts to lower the threshold for B cell activation. Although previous studies have used anti-CR2 Abs or used chimeric Ags in the context of BCR transgenic mice as surrogate C3d-containing ligands, we have used a physiological form of C3d to study signaling in B cells from wild-type C57BL/6 mice. We find that while CR2-enhanced BCR signaling causes intracellular Ca2+ mobilization and total pTyr phosphorylation of an intensity comparable to optimal BCR ligation using anti-IgM Abs, it does so with limited activation of inhibitory effectors (such as CD22, Src homology region 2 domain containing phosphatase 1, and SHIP-1) and without substantial receptor cross-linking. In summary, we demonstrate that CR2-enhanced BCR signaling may proceed not only through the previously described amplification of positive signaling pathways, but is potentially augmented by a lack of normal inhibitory/feedback signaling.