bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of Surfactant Proteins A, D, and C1q in the Clearance of Apoptotic Cells In Vivo and In Vitro: Calreticulin and CD91 as a Common Collectin Receptor Complex
Authors: Vandivier R. William , Ogden Carol Anne , Fadok Valerie A. , Hoffmann Peter R. , Brown Kevin K. , Botto Marina , Walport Mark J. , Fisher James H. , Henson Peter M. , Greene Kelly E. 
Published: April 2014

AbstractRemoval of cells dying by apoptosis is essential to normal development, maintenance of tissue homeostasis, and resolution of inflammation. Surfactant protein A (SP-A) and surfactant protein D (SP-D) are high abundance pulmonary collectins recently implicated in apoptotic cell clearance in vitro. Other collectins, such as mannose-binding lectin and the collectin-like C1q, have been shown to bind to apoptotic cells and drive ingestion through interaction with calreticulin and CD91 on the phagocyte in vitro. However, only C1q has been shown to enhance apoptotic cell uptake in vivo. We sought to determine the relative importance of SP-A, SP-D, and C1q in pulmonary clearance of apoptotic cells using knockout and overexpressing mice, and to determine the role of calreticulin and CD91 in this process. SP-A, SP-D, and C1q all enhanced apoptotic cell ingestion by resident murine and human alveolar macrophages in vitro. However, only SP-D altered apoptotic cell clearance from the naive murine lung, suggesting that SP-D plays a particularly important role in vivo. Similar to C1q and mannose-binding lectin, SP-A and SP-D bound to apoptotic cells in a localized, patchy pattern and drove apoptotic cell ingestion by phagocytes through a mechanism dependent on calreticulin and CD91. These results suggest that the entire collectin family of innate immune proteins (including C1q) works through a common receptor complex to enhance removal of apoptotic cells, and that collectins are integral, organ-specific components of the clearance machinery.
Breakdown of CTL Tolerance to Self HLA-B*2705 Induced by Exposure toChlamydia trachomatis
Authors: Popov Igor , Cruz Charles S. Dela , Barber Brian H. , Chiu Basil , Inman Robert D. 
Published: April 2014

AbstractThere is a strong association between seronegative arthritis and HLA B27, but it is still unresolved whether the contribution of B27 to disease pathogenesis is solely as a restriction element for an arthritogenic peptide, or whether B27 itself serves as an autoantigen. This study uses transgenic rats to address the question as to whether exposure to an arthritogenic pathogen can alter tolerance to B27. Unlike their nontransgenic counterparts, B27-transgenic rats are tolerant of B27 immunization using either B27+ splenocytes or plasmid DNA and do not develop anti-B27 CTL. However, if splenocytes from such immunized animals are exposed to Chlamydia in vitro, CTL are generated that lyse B27+ targets. No killing was seen with targets transfected with control B7, B14, B40, or B44. This phenomenon was not observed with immunization by nontransgenic splenocytes, or HLA-A2 DNA alone. Using targets expressing mutated B27, we show that the epitope for autoreactive CTL recognition of B27 involves the Lys70 amino acid residue in the α1 domain of the MHC class I molecule. The generation of CTL with specificity for B27 under these conditions demonstrates that tolerance to B27 can be subverted by Chlamydia. This indicates a dynamic interrelationship between the pathogen and B27, which may have important implications for B27-related spondyloarthropathies triggered by intracellular bacteria.
Cutting Edge: CATERPILLER: A Large Family of Mammalian Genes Containing CARD, Pyrin, Nucleotide-Binding, and Leucine-Rich Repeat Domains
Authors: Harton Jonathan A. , Linhoff Michael W. , Zhang Jinghua , Ting Jenny P.-Y. 
Published: April 2014

Abstract
Large mammalian proteins containing a nucleotide-binding domain (NBD) and C-terminal leucine-rich repeats (LRR) similar in structure to plant disease resistance proteins have been suggested as critical in innate immunity. Our interest in CIITA, a NBD/LRR protein, and recent reports linking mutations in two other NBD/LRR proteins to inflammatory disorders have prompted us to perform a search for other members. Twenty-two known and novel NBD/LRR genes are spread across eight human chromosomes, with multigene clusters occurring on 11, 16, and 19. Most of these are telomeric. Their N termini vary, but most have a pyrin domain. The genomic organization demonstrates a high degree of conservation of the NBD- and LRR-encoding exons. Except for CIITA, all the predicted NBD/LRR proteins are likely ATP-binding proteins. Some have broad tissue expression, whereas others are restricted to myeloid cells. The implications of these data on origins, expression, and function of these genes are discussed.
Cutting Edge: A Crucial Role for B7-CD28 in Transmitting T Help from APC to CTL
Authors: Prilliman Kiley R. , Lemmens Edward E. , Palioungas Georgia , Wolfe Thomas G. , Allison James P. , Sharpe Arlene H. , Schoenberger Stephen P. 
Published: April 2014

Abstract
Although APC activation via CD40-CD40L signaling plays a critical role in enabling CD4+ T cells to provide the “help” necessary for cross-priming of naive CTL, it is unclear how this makes the APC competent for priming. We have investigated the roles of B7-1/B7-2 and their TCRs CD28/CTLA-4 in cross-priming of CD4-dependent CTL in vivo. We find that both CD28 and B7-1/B7-2 are required for CD40-activated APC to cross-prime CTL, and that priming by CD40-activated APC was prevented by blockade of CD28. Conversely, augmenting CD28 signals with an agonistic Ab bypassed the requirement for CD4+ T help or CD40 activation. Interestingly, blockade of the negative regulatory B7 receptor CTLA-4 failed to prime CTL in the absence of T help. These results support a model in which activation-induced up-regulation of B7 molecules on APC leads to increased CD28 signaling and a commitment to cross-priming of CD4-dependent CTL.
Cutting Edge: Down-Regulation of MICA on Human Tumors by Proteolytic Shedding
Authors: Salih Helmut R. , Rammensee Hans-Georg , Steinle Alexander 
Published: April 2014

Abstract
The immunoreceptor NKG2D stimulates tumor immunity through activation of CD8 T cells and NK cells. Its ligand MICA has been shown to be broadly expressed on human tumors of epithelial origin. MICA expression correlates with an enrichment of Vδ1 T cells in tumor tissue. We report that human tumor cells spontaneously release a soluble form of MICA encompassing the three extracellular domains, which is present at high levels in sera of patients with gastrointestinal malignancies, but not in healthy donors. Release of MICA from tumor cells is blocked by inhibition of metalloproteinases, concomitantly causing accumulation of MICA on the cell surface. Shedding of MICA by tumor cells may modulate NKG2D-mediated tumor immune surveillance. In addition, determination of soluble MICA levels may be implemented as an immunological diagnostic marker in patients with epithelial malignancies.
Antisense Cyclic Adenosine 5′-Monophosphate Response Element Modulator Up-Regulates IL-2 in T Cells from Patients with Systemic Lupus Erythematosus
Authors: Tenbrock Klaus , Juang Yuang-Taung , Gourley Mark F. , Nambiar Madhusoodana P. , Tsokos George C. 
Published: April 2014

AbstractThe cAMP response element modulator (CREM) has been shown to bind specifically to the −180 site of the IL-2 promoter in vitro. CREM protein is increased in T cells of patients with systemic lupus erythematosus (SLE), and it has been considered responsible for the decreased production of IL-2. In this work we show that transcriptional up-regulation is responsible for the increased CREM protein levels and that CREM binds to the IL-2 promoter in live SLE T cells. Suppression of the expression of CREM mRNA and protein by an antisense CREM plasmid, which was force expressed in SLE T cells by electroporation, resulted in decreased CREM protein binding to the IL-2 promoter and increased expression of IL-2 mRNA and protein. Our data demonstrate that antisense constructs can be used to effectively eliminate the expression of a transcriptional repressor. This approach can be used therapeutically in conditions where increased production of IL-2 is desired.
Generation Ex Vivo of TGF-β-Producing Regulatory T Cells from CD4+CD25− Precursors
Authors: Zheng Song Guo , Gray J. Dixon , Ohtsuka Kazuo , Yamagiwa Satoshi , Horwitz David A. 
Published: April 2014

AbstractPreviously we reported that TGF-β has an important role in the generation and expansion of human “professional” CD4+CD25+ regulatory T cells in the periphery that have a cytokine-independent mechanism of action. In this study we used low-dose staphylococcal enterotoxin to induce T cell-dependent Ab production. We report that TGF-β induces activated CD4+CD25− T cells to become Th3 suppressor cells. While stimulating CD4+ cells with TGF-β modestly increased expression of CD25 and intracellular CTLA-4 in primary cultures, upon secondary stimulation without TGF-β the total number and those expressing these markers dramatically increased. This expansion was due to both increased proliferation and protection of these cells from activation-induced apoptosis. Moreover, adding as few as 1% of these TGF-β-primed CD4+ T cells to fresh CD4+ cells and B cells markedly suppressed IgG production. The inhibitory effect was mediated by TGF-β and was also partially contact dependent. Increased TGF-β production was associated with a decreased production of IFN-γ and IL-10. Depletion studies revealed that the precursors of these TGF-β-producing CD4+ suppressor cells were CD25 negative. These studies provide evidence that CD4+CD25+ regulatory cells in human blood consist of at least two subsets that have TGF-β-dependent and independent mechanisms of action. TGF-β has an essential role in the generation of both of these T suppressor cell subsets from peripheral T cells. The ability to induce CD4+ and CD8+ cells to become regulatory cells ex vivo has the potential to be useful in the treatment of autoimmune diseases and to prevent transplant rejection.
Crucial Role of DNA Methylation in Determination of Clonally Distributed Killer Cell Ig-like Receptor Expression Patterns in NK Cells
Authors: Santourlidis Simeon , Trompeter Hans-Ingo , Weinhold Sandra , Eisermann Britta , Meyer Klaus L. , Wernet Peter , Uhrberg Markus 
Published: April 2014

AbstractHuman NK cells are characterized by the expression of surface receptors of the killer cell Ig-like receptor (KIR) family, which are involved in the specific recognition of pathogenic target cells. Each NK cell expresses and maintains an individual subset of inhibitory and stimulatory KIR and in this way contributes to a diversified NK cell repertoire. To date, the molecular basis for generation of clonally distributed KIR expression patterns has been elusive. Here, analyses of DNA methylation patterns of KIR genes in NK cell lines as well as in NK cells, freshly isolated from peripheral blood, demonstrated that a small CpG island surrounding the transcriptional start site of each KIR gene is consistently demethylated in expressed KIR and methylated in unexpressed KIR. DNA-demethylating treatment resulted in a rapid and stable induction of transcription and cell surface expression of all formerly unexpressed KIR in NK cell lines, NK cell clones, and freshly isolated NK cells, but not in other cell types. In vitro methylation of KIR CpG islands repressed reporter gene expression in NK cells. We conclude that clonal patterns of KIR expression are mainly epigenetically determined and maintained through DNA methylation.
Pentoxifylline Functions As an Adjuvant In Vivo to Enhance T Cell Immune Responses by Inhibiting Activation-Induced Death
Authors: Suresh Radhakrishnan , Vig Monika , Bhatia Sumeena , Goodspeed Eric P. B. , John Beena , Kandpal Usha , Srivastava Smita , George Anna , Sen Ranjan , Bal Vineeta , Durdik Jeannine M. , Rath Satyajit 
Published: April 2014

AbstractModalities for inducing long-lasting immune responses are essential components of vaccine design. Most currently available immunological adjuvants empirically used for this purpose cause some inflammation, limiting clinical acceptability. We show that pentoxifylline (PF), a phosphodiesterase (PDE) inhibitor in common clinical use, enhances long-term persistence of T cell responses, including protective responses to a bacterial immunogen, Salmonella typhimurium, via a cAMP-dependent protein kinase A-mediated effect on T cells if given to mice for a brief period during immunization. PF inhibits activation-mediated loss of superantigen-reactive CD4 as well as CD8 T cells in vivo without significantly affecting their activation, and inhibits activation-induced death and caspase induction in stimulated CD4 as well as CD8 T cells in vitro without preventing the induction of activation markers. Consistent with this ability to prevent activation-induced death in not only CD4 but also CD8 T cells, PF also enhances the persistence of CD8 T cell responses in vivo. Thus, specific inhibition of activation-induced T cell apoptosis transiently during immune priming is likely to enhance the persistence of CD4 and CD8 T cell responses to vaccination, and pharmacological modulators of the cAMP pathway already in clinical use can be used for this purpose as immunological adjuvants.
The Notch Ligand Jagged-1 Is Able to Induce Maturation of Monocyte-Derived Human Dendritic Cells
Authors: Weijzen Sanne , Velders Markwin P. , Elmishad Amira G. , Bacon Patricia E. , Panella Jeffrey R. , Nickoloff Brian J. , Miele Lucio , Kast W. Martin 
Published: April 2014

Abstract
Notch receptors play a key role in several cellular processes including differentiation, proliferation, and apoptosis. This study investigated whether the activation of Notch signaling would affect the maturation of dendritic cells (DCs). Direct stimulation of Notch signaling in DCs with a peptide ligand induced DC maturation, similar to LPS: DCs up-regulated maturation markers, produced IL-12, lost endocytosis capacity, and became able to activate allogeneic T cells. Furthermore, coculture of DCs with cells expressing Notch ligand Jagged-1 induced up-regulation of maturation markers, IL-12 production, T cell proliferative responses, and IFN-γ production. Our data suggest that activation of Notch by Jagged-1 plays an important role in maturation of human DCs. Additionally, they reveal a novel role for Notch signaling in cell maturation events distal to the cell fate decision fork. These data may have important medical implications, since they provide new reagents to induce DC activity, which may be beneficial as adjuvants in situations where an immune response needs to be elicited, such as tumor immunotherapy.
BLyS and APRIL Form Biologically Active Heterotrimers That Are Expressed in Patients with Systemic Immune-Based Rheumatic Diseases
Authors: Roschke Viktor , Sosnovtseva Svetlana , Ward Christopher D. , Hong June S. , Smith Rodger , Albert Vivian , Stohl William , Baker Kevin P. , Ullrich Stephen , Nardelli Bernardetta , Hilbert David M. , Migone Thi-Sau 
Published: April 2014

AbstractBLyS and APRIL are two members of the TNF superfamily that are secreted by activated myeloid cells and have costimulatory activity on B cells. BLyS and APRIL share two receptors, TACI and BCMA, whereas a third receptor, BAFF-R, specifically binds BLyS. Both BLyS and APRIL have been described as homotrimeric molecules, a feature common to members of the TNF superfamily. In this study, we show that APRIL and BLyS can form active heterotrimeric molecules when coexpressed and that circulating heterotrimers are present in serum samples from patients with systemic immune-based rheumatic diseases. These findings raise the possibility that active BLyS/APRIL heterotrimers may play a role in rheumatic and other autoimmune diseases and that other members of the TNF ligand superfamily may also form active soluble heterotrimers.
Amelioration of Collagen-Induced Arthritis by Blockade of Inducible Costimulator-B7 Homologous Protein Costimulation
Authors: Iwai Hideyuki , Kozono Yuko , Hirose Sachiko , Akiba Hisaya , Yagita Hideo , Okumura Ko , Kohsaka Hitoshi , Miyasaka Nobuyuki , Azuma Miyuki 
Published: April 2014

Abstract
B7 homologous protein (B7h)/B7-related protein 1 (B7RP-1) is a new member of the B7 family of costimulatory molecules that specifically interacts with inducible costimulator (ICOS) expressed on activated T cells. Collagen type II (CII)-induced arthritis (CIA) is an experimental model of arthritis that has been used to dissect the pathogenesis of human rheumatoid arthritis. In this study, we have investigated the effect of neutralizing anti-B7h mAb on the development and disease progression of CIA. Administration of anti-B7h mAb significantly ameliorated the disease as assessed by clinical arthritis score and histology in the joints, and a beneficial effect was also obtained by a delayed treatment after the onset of disease. Expression of ICOS and B7h was observed in the inflamed synovial tissue as well as in the draining lymph nodes (LNs) and expansion of ICOS+ T cells in the LN was reduced by the anti-B7h mAb treatment. Expression of mRNA for proinflammatory cytokines such as TNF-α, IL-1β, and IL-6 in the joints was inhibited by the treatment. Proliferative responses and production of IFN-γ and IL-10 upon restimulation with CII in vitro were significantly inhibited in LN cells from the anti-B7h mAb-treated mice. Serum anti-CII IgG1, IgG2a, and IgG2b levels were also reduced. Our present results showed a beneficial effect of the B7h blockade on CIA through anti-inflammatory actions and inhibition of both Th1- and Th2-mediated immune responses, suggesting that the ICOS-B7h interaction plays an important role in the pathogenesis of CIA and thus the blockade of this pathway may be beneficial for the treatment of human rheumatoid arthritis.
Src Homology 2 Domain-Containing Inositol Polyphosphate Phosphatase Regulates NF-κB-Mediated Gene Transcription by Phagocytic FcγRs in Human Myeloid Cells
Authors: Tridandapani Susheela , Wang Yijie , Marsh Clay B. , Anderson Clark L. 
Published: April 2014

AbstractFcγR-mediated phagocytosis is accompanied by the generation of tissue-damaging products such as inflammatory cytokines and reactive oxygen species. Hence, the phagocytic response must be a tightly regulated process. Recent studies have established that clustering FcγR on human myeloid cells causes tyrosine phosphorylation of Src homology 2 domain-containing inositol polyphosphate phosphatase (SHIP). However, it is not known how these immunoreceptor tyrosine-based activation motif (ITAM)-bearing phagocytic FcγR activate SHIP, or whether the activation of SHIP by ITAMs has any functional relevance. Experiments addressing the mechanism of SHIP association with ITAMs have been done in in vitro systems using phosphopeptides. In this study we undertook to dissect the molecular mechanism by which SHIP associates with the native ITAM-FcγR and becomes phosphorylated. In this report we provide evidence that first, SHIP is indeed phosphorylated by ITAM-FcγR, using cell systems that lack FcγRIIb expression; second, coimmunoprecipitation experiments demonstrate that SHIP associates with native ITAM-bearing FcγRIIa in vivo; and third, phosphorylation of SHIP by FcγRIIa is inhibited by overexpressing either the SHIP Src homology 2 domain or a dominant negative mutant of Shc. In contrast, SHIP phosphorylation was not inhibited by a dominant negative mutant of Grb2. We extend these observations to show that SHIP activation by ITAM-FcγR down-regulates NF-κB-induced gene transcription. These findings both provide a molecular mechanism for SHIP association with native ITAM-bearing receptors and demonstrate that SHIP association with ITAM-FcγR serves to regulate gene expression during the phagocytic process.
Enhancement of Complement Activation and Opsonophagocytosis by Complexes of Mannose-Binding Lectin with Mannose-Binding Lectin-Associated Serine Protease After Binding toStaphylococcus aureus
Authors: Neth Olaf , Jack Dominic L. , Johnson Marina , Klein Nigel J. , Turner Malcolm W. 
Published: April 2014

AbstractHuman mannose-binding lectin (MBL) is a serum protein of the innate immune system that circulates as a complex with a group of so-called MBL-associated serine proteases (MASP-1, MASP-2, and MASP-3). Complexes of MBL-MASP2 are able to activate the complement system in an Ab and C1-independent fashion after binding of the lectin to appropriate microbial sugar arrays. We have evaluated the additive effect of the lectin pathway relative to other complement activation pathways and the subsequent effect on neutrophil phagocytosis. Complement activation in the sera of MBL-deficient individuals was studied with and without the addition of exogenous MBL-MASP. Flow cytometry was used to measure the deposition of C4, factor B, C3b, and iC3b on Staphylococcus aureus. Deposition of the first cleavage product of the lectin pathway, C4b, was increased using the sera of three different MBL-deficient individuals when exogenous MBL-MASP was added. Factor B was deposited in association with C4, but there was no evidence of independent alternative pathway activation. Similar enhancement of C3b deposition was also observed, with evidence of elevated amounts of C3b processed to iC3b. The increase in opsonic C3 fragments mediated by MBL was associated with a significant increase in the uptake of organisms by neutrophils. We also observed significant increases in phagocytosis with MBL-MASPs that were independent of complement activation. We conclude that MBL-MASP makes a major contribution to complement-mediated host defense mechanisms.
Neutrophil Influx in Response to a Peritoneal Infection with Salmonella Is Delayed in Lipopolysaccharide-Binding Protein or CD14-Deficient Mice
Authors: Yang Kang K. , Dorner Brigitte G. , Merkel Ulrike , Ryffel Bernard , Schütt Christine , Golenbock Douglas , Freeman Mason W. , Jack Robert S. 
Published: April 2014

Abstract
The induction of an adaptive immune response to a previously unencountered pathogen is a time-consuming process and initially the infection must be held in check by the innate immune system. In the case of an i.p. infection with Salmonella typhimurium, survival requires both CD14 and LPS-binding protein (LBP) which, together with Toll-like receptor 4 and myeloid differentiation protein 2, provide a sensitive means to detect bacterial LPS. In this study, we show that in the first hours after i.p. infection with Salmonella a local inflammatory response is evident and that concomitantly neutrophils flood into the peritoneum. This rapid neutrophil influx is dependent on TNF since it is 1) abolished in TNF KO mice and 2) can be induced by i.p. injection of TNF in uninfected animals. Neutrophil influx is not strictly dependent on the presence of either LBP or CD14. However, in their absence, no local inflammatory response is evident, neutrophil migration is delayed, and the mice succumb to the infection. Using confocal microscopy, we show that the neutrophils which accumulate in CD14 and LBP null mice, albeit with delayed kinetics, are nevertheless fully capable of ingesting the bacteria. We suggest that the short delay in neutrophil influx gives the pathogen a decisive advantage in this infection model.