bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of E-Portfolio Software
Authors: Himpsl Klaus , Baumgartner Peter
Published: March 2009

E-Portfolios are a new type of software and it is still relatively vague to determine, which functions are obligatory â?? that is which functions constitute characteristic features â?? and which functions are just optional (â??nice to haveâ??). This article describes the concept and the preliminary results of a research project which was conducted to evaluate E-Portfolio software, and aims at providing decision guidance for implementing E-Portfolios in higher education - first and foremost from the pedagogical perspective. Which recommendations can be made to an institution which now wants to implement electronic portfolios with a certain objective?
Results From a Hindcast Study of the Ocean Circulation Africa
Authors: Evensen Geir
Published: March 2009

This paper presents results from a circulation model for the west Africancoast. The model covers all of the southern Atlantic but has enhancedresolution along the west African coast and in particular in the Angola Basinand Gulf of Guinea. An 11 year hind cast run was performed from 1986 to 1996using synoptic forcing fields. This simulation has produced a large amount ofdata which has been analyzed and intercompared with results in the openliterature, and a validation has been carried out using current meter data fromseveral locations off the west coast of Africa.

Introduction

The oceanic processes along the western coast of Africa are strongly influencedby the Equatorial current system. The Northern Equatorial Counter Current(NECC) which continues as the Guinea Current (GC) induces strong currents andupwelling along the Ivory Coast. The Benguela Current (BC) originates from thedynamically active Benguela upwelling zone and propagates Northwards along thecoast until it separates and feeds into the Southern Equatorial Current (SEC). The Equatorial undercurrents affect the characteristics of water masses alongthe west African coast, where they also feed poleward undercurrents.

Thus, to have a realistic model for the circulation along the west coast of Africa which can be integrated for many years without being influenced by poorspecification of open boundary conditions, one either has to use a rather largedomain or alternatively nest a high resolution coastal model into a large scale South Atlantic model. The approach taken here is to apply a "global"South Atlantic model with variable grid resolution which is enhanced along thewest African coast. This allows for high resolution coastal modeling studieswithout having to specify open boundary conditions for a regional model. Theopen boundaries can be moved far enough away to not influence the particularregion of interest.

In the next Section the general model setup is discussed. Thereafter a fewexamples from the model results will be shown, and finally some results from astatistical validation will be presented.

Model setup

The physical model to be used is based on the Miami Isopycnic Coordinate Ocean Model (MICOM) which is an isopycnic dynamic-thermodynamic ocean generalcirculation model developed by Bleck and coworkers1,2,3,4. In thevertical, MICOM uses potential density as the coordinate. This can clearly bedone since the stratification is a monotone function of depth, thus changing todensity as a coordinate, does not involve any assumptions or simplifications. The advantage of using density surfaces as a coordinate is evident since theeddy mixing in the ocean is mainly along neutral surfaces, or approximatelysurfaces of constant density. The cross isopycnal mixing is orders of magnitudelower5 and can in most model experiments be neglected (except forlong term climate simulations). This leads to a formalism where the ocean isdivided into a number of layers each having a density which is constant in timeand increasing with depth.
Measuring the Bathymetry of Shallow Seas Using Radar Imagery From Satellite and Aircraft
Authors: de Valk C.F. , Wensink G.J.
Published: March 2009

Introduction

Under the appropriate conditions, satellite or aircraft radar images overshallow seas show features of the seabed. These conditions are a reasonablystrong current, a moderate wind speed, a stable atmosphere and a well-mixedwater column. The underlying mechanism is that depth variations inducevariations in the tidal current, which affect the surface waves and thereforeradar backscatter. Use of radar images to map the seabed topography is nottrivial, as the image brightness pattern depends on current direction, wind-wave direction and the orientation of the topographic features to becharted.

ARGOSS has developed techniques for mapping of the seabed that use radar imagesas the primary data source and a limited number of sounding data forcalibration. The most recent version of this mapping software, BAS2D, incorporates a comprehensive model of the physical mechanisms involved. Potential advantages of the technique are that fewer sounding data are neededto obtain charts with the same degree of detail and accuracy, and possibly alsothat charts can be updated more frequently without requiring more frequentship-borne surveys.

The BAS2D software is currently being tested on both satellite imagery andairborne imagery in differnt radar wavelength bands. Tests of the method on L-and C-band aircraft imagery planned for last year were postponed due toproblems with data acquisition, but they will be completed in the course ofthis year.

This paper discusses case studies carried out using C-band radar imagery fromthe ERS-2 satellite at two sites in the North Sea.

One is the Plaatgat area near a tidal inlet between the islands of Ameland andSchiermonnikoog in the north of the Netherlands, and the other in the FlemishBanks of the coast of Belgium. The morphology and the hydraulic regime of thesesites are very different. The dominant seabed features in the Plaatgat area aredeep curved tidal channels and shoals. BAS2D has been used to produce maps of a3 km × 3 km area with a resolution of 50 m × 50 m which were compared withsoundings along tracks at 200 m intervals from Rijkswaterstaat. The FlemishBanks test area is characterised by large banks almost parallel to thecoastline with on top of these short steep sand waves with wavelengths about200 m. A small area of 1.5 km by 1.5 km of the Kwintebank was charted with aresolution of 25 m × 25 m using a SAR image as well as sounding data from WWK(Administration of Water Infrastructure and Sea Affairs) in Belgium.

Methods

Under favourable meteorological and hydrodynamic conditions (moderate winds of3 to 10 m/s, a neutrally stable atmosphere and moderate tidal currents of about0.5 m/s), Synthetic Aperture Radar (SAR) imagery shows features of the bottomtopography of shallow seas (Alpers and Hennings 1984).
Enabling Enhancements of Riser VIV Design Techniques Through Detailed Interpretation of Test Results for VIV Suppression Devices
Authors: Spencer Don , Leverette Steve , Masters Rodney , Quinn Ronan , Schaudt Kenneth J.
Published: March 2009

This paper presents the developments and key findings of a comprehensive test program executed by AIMS International, Inc. to predict the effectiveness of various Vortex-Induced-Vibration (VIV) suppression devices for riser systems. In addition, the test results were fully integrated into a widely-used riser analysis numerical code, whereby the suppression characteristics of the test devices were compared with standard design practices for a typical riser concept.

This paper will discuss the (1) extensive testing of conventional and ROV deployable VIV suppression systems; (2) development of stable, low-drag fairing designs that are not subject to galloping; (3) implementation of these systems in the empirical models such as SHEAR7 and; (4) evaluation of the impact of such suppression devices.

Introduction

The search for, and production of, hydrocarbon has been relentlessly moving into deeper and deeper water. In the Gulf of Mexico where much of this deep water activity has been pioneered, slender and flexible components are used to moor floating platforms or to transport fluids to and from the seabed. The Loop Current and its associated eddies interact with these relatively bluff bodies causing the shedding of von Karmen vortices. Under certain conditions, the interaction of the vortices with the body produces VIV. This phenomenon can significantly increase the drag of the body and the vibration can lead to shortened life through fatigue. In the Gulf of Mexico, the problem is compounded by several factors: as production moves into deeper water the Loop Current and its associated eddies become stronger and more prevalent, the risers need more external buoyancy to support their weight hence their diameter increases and, of course, the risers are longer. All of these factors contribute to the overall drag of the riser or drill string and must be carried by the floating platform and its mooring or positioning system.
The Heme Oxygenase-1/Carbon Monoxide Pathway Suppresses TLR4 Signaling by Regulating the Interaction of TLR4 with Caveolin-1
Authors: Wang Xiao Mei , Kim Hong Pyo , Nakahira Kiichi , Ryter Stefan W. , Choi Augustine M. K.
Published: March 2009

Caveolin-1 (cav-1), the principle structural protein of plasmalemmal caveolae, regulates inflammatory signaling processes originating at the membrane. We show that cav-1 bound to TLR4 and inhibited LPS-induced proinflammatory cytokine (TNF-α and IL-6) production in murine macrophages. Mutation analysis revealed a cav-1 binding motif in TLR4, essential for this interaction and for attenuation of proinflammatory signaling. Cav-1 was required for the anti-inflammatory effects of carbon monoxide (CO), a product of heme oxygenase-1 (HO-1) activity. CO augmented the cav-1/TLR4 interaction. Upon LPS stimulation, HO-1 trafficked to the caveolae by a p38 MAPK-dependent mechanism, where it down-regulated proinflammatory signaling. These results reveal an anti-inflammatory network involving cav-1 and HO-1.
Cutting Edge: The PTPN22 Allelic Variant Associated with Autoimmunity Impairs B Cell Signaling
Authors: Arechiga Adrian F. , Habib Tania , He Yantao , Zhang Xian , Zhang Zhong-Yin , Funk Andrew , Buckner Jane H.
Published: March 2009

PTPN22 is a gene encoding the protein tyrosine phosphatase Lyp. A missense mutation changing residue 1858 from cytosine to thymidine (1858C/T) is associated with multiple autoimmune disorders. Studies have demonstrated that Lyp has an inhibitory effect on TCR signaling; however, the presence of autoantibodies in all of the diseases associated with the 1858T variant and recent evidence that Ca2+ flux is altered in B cells of 1858T carriers indicate a role for Lyp in B cell signaling. In this study we show that B cell signal transduction is impaired in individuals who express the variant. This defect in signaling is characterized by a deficit in proliferation, a decrease in phosphorylation of key signaling proteins, and is reversed by inhibition of Lyp. These findings suggest that the PTPN22 1858T variant alters BCR signaling and implicate B cells in the mechanism by which the PTPN22 1858T variant contributes to autoimmunity.
Chlamydia trachomatis Infection Modulates Trophoblast Cytokine/Chemokine Production
Authors: de la Torre Eugenia , Mulla Melissa J. , Yu Andrew G. , Lee Seung-Joon , Kavathas Paula B. , Abrahams Vikki M.
Published: March 2009

It is well established that intrauterine infections can pose a threat to pregnancy by gaining access to the placenta and fetus, and clinical studies have strongly linked bacterial infections with preterm labor. Although Chlamydia trachomatis (Ct) can infect the placenta and decidua, little is known about its effects on trophoblast cell immune function. We have demonstrated that Ct infects trophoblast cells to form inclusions and completes the life cycle within these cells by generating infectious elementary bodies. Moreover, infection with Ct leads to differential modulation of the trophoblast cell’s production of cytokines and chemokines. Using two human first trimester trophoblast cell lines, Sw.71 and H8, the most striking feature we found was that Ct infection results in a strong induction of IL-1β secretion and a concomitant reduction in MCP-1 (CCL2) production in both cell lines. In addition, we have found that Ct infection of the trophoblast results in the cleavage and degradation of NF-κB p65. These findings suggest that the effect of a Chlamydia infection on trophoblast secretion of chemokines and cytokines involves both activation of innate immune receptors expressed by the trophoblast and virulence factors secreted into the trophoblast by the bacteria. Such altered trophoblast innate immune responses may have a profound impact on the microenvironment of the maternal-fetal interface and this could influence pregnancy outcome.
TLR-9 Activation Aggravates Concanavalin A-Induced Hepatitis via Promoting Accumulation and Activation of Liver CD4+ NKT Cells
Authors: Jiang Wei , Sun Rui , Zhou Rongbin , Wei Haiming , Tian Zhigang
Published: March 2009

Increasing evidence suggests that TLRs are involved in the pathogenesis of liver diseases; however, the underlying mechanisms remain obscure. In this study, we found that treatment with CpG-oligodeoxynucleotide (ODN) promoted the accumulation and activation of murine hepatic NKT cells. Additional experiments showed that CpG-ODN preferred to act on CD4+ NKT cells, while having less effect on CD4− NKT cells. The effect of CpG-ODN on liver NKT cells depended on the presence of Kupffer cells and IL-12. Meanwhile, CpG-ODN pretreatment aggravated liver injury and promoted the production of inflammatory cytokines in a Con A-induced fulminant hepatitis model via TLR9 activation. Collectively, our data demonstrate that TLR9 stimulation prefers to promote the accumulation and activation of hepatic CD4+ NKT cells and suggest that TLR9 signaling might be involved in the pathogenesis of human hepatitis.
MHC Class I/Peptide Transfer between Dendritic Cells Overcomes Poor Cross-Presentation by Monocyte-Derived APCs That Engulf Dying Cells
Authors: Qu Chunfeng , Nguyen Van Anh , Merad Miriam , Randolph Gwendalyn J.
Published: March 2009

In vivo data suggest that monocytes participate critically in cross-presentation, but other data suggest that lymph node resident dendritic cells (DCs) mainly cross-present. Here, we utilized a three-dimensional model of a blood vessel wall that endogenously supports DC development from human monocytes, and we incorporated dying autologous cells in the subendothelial matrix of the model. Flu-infected dying cells promoted monocytes to become mature DCs and cross-present cell-associated Ags for the activation of CTLs. Similar responses were induced by loading the dying cells with the TLR7/8 ligand ssRNA, whereas dying cells loaded with TLR3 ligand were less efficient. Monocyte-derived DCs that developed in this model cross-presented Ag to T cells efficiently regardless of whether they engulfed detectable amounts of labeled dying cells. Unexpectedly, the monocyte-derived cells that directly engulfed dying cells in vitro were not the major APCs stimulating CD8+ lymphocytes. Instead, bystander DCs acquired more robust capacity to cross-prime through receipt of MHC class I/peptide from the phagocytic, monocyte-derived cells. In mice, lymph node-homing monocyte-derived DCs processed Ags from engulfed cells and then transferred MHC class I/peptide complexes to confer cross-priming capacity to MHC class I-deficient lymph node resident CD8α+ DCs. Thus, natural or synthetic TLR7/8 agonists contained within dying cells promote the conversion of monocytes to DCs with capacity for cross-presentation and for “cross-dressing” other DCs. These data reveal a way in which migratory monocyte-derived DCs and other DCs, like lymph node resident DCs, both mediate cross-presentation.
Tc17, a Unique Subset of CD8 T Cells That Can Protect against Lethal Influenza Challenge
Authors: Hamada Hiromasa , Garcia-Hernandez Maria de la Luz , Reome Joyce B. , Misra Sara K. , Strutt Tara M. , McKinstry Kai K. , Cooper Andrea M. , Swain Susan L. , Dutton Richard W.
Published: March 2009

We show here that IL-17-secreting CD4 T (Th)17 and CD8 T (Tc)17 effector cells are found in the lung following primary challenge with influenza A and that blocking Ab to IL-17 increases weight loss and reduces survival. Tc17 effectors can be generated in vitro using naive CD8 T cells from OT-I TCR-transgenic mice. T cell numbers expand 20-fold and a majority secretes IL-17, but little IFN-γ. Many of the IL-17-secreting cells also secrete TNF and some secrete IL-2. Tc17 are negative for granzyme B, perforin message, and cytolytic activity, in contrast to Tc1 effectors. Tc17 populations express message for orphan nuclear receptor γt and FoxP3, but are negative for T-bet and GATA-3 transcription factors. The FoxP3-positive, IL-17-secreting and IFN-γ-secreting cells represent three separate populations. The IFN-γ-, granzyme B-, FoxP3-positive cells and cells positive for IL-22 come mainly from memory cells and decrease in number when generated from CD44low rather than unselected CD8 T cells. Cells of this unique subset of CD8 effector T cells expand greatly after transfer to naive recipients following challenge and can protect them against lethal influenza infection. Tc17 protection is accompanied by greater neutrophil influx into the lung than in Tc1-injected mice, and the protection afforded by Tc17 effectors is less perforin but more IFN-γ dependent, implying that different mechanisms are involved.
Critical Role for STAT3 in IL-17A-Mediated CCL11 Expression in Human Airway Smooth Muscle Cells
Authors: Saleh Ali , Shan Lianyu , Halayko Andrew J. , Kung Sam , Gounni Abdelilah S.
Published: March 2009

IL-17A has been shown to be expressed at higher levels in respiratory secretions from asthmatics and to correlate with airway hyperresponsiveness. Although these studies raise the possibility that IL-17A may influence allergic disease, the mechanism remains unknown. We previously demonstrated that IL-17A mediates CC chemokine (CCL11) production from human airway smooth muscle (ASM) cells. In this study, we demonstrate that STAT3 activation is critical in IL-17A-mediated CCL11 expression in ASM cells. IL-17A mediated a rapid phosphorylation of STAT3 but not STAT6 or STAT5 in ASM cells. Interestingly, transient transfection with wild-type or mutated CCL11 promoter constructs showed that IL-17A-mediated CCL11 expression relies on the STAT6 binding site. However, STAT3 but not STAT6 in vivo binding to the CCL11 promoter was detected following IL-17A stimulation of ASM cells. Overexpression of DN STAT3 (STAT3β) abolishes IL-17A-induced CCL11 promoter activity. This effect was not observed with STAT6 DN or the STAT3 mutant at Ser727. Interestingly, disruption of STAT3 activity with the SH2 domain binding peptide, but not with control peptide, results in a significant reduction of IL-17A-mediated STAT3 phosphorylation and CCL11 promoter activity. IL-17A-mediated CCL11 promoter activity and mRNA were significantly diminished in STAT3- but not STAT6-silenced ASM cells. Finally, IL-17A-induced STAT3 phosphorylation was sensitive to pharmacological inhibitors of JAK2 and ERK1/2. Taken together, our data provide the first evidence of IL-17A-mediated gene expression via STAT3 in ASM cells. Collectively, our results raise the possibility that the IL-17A/STAT3 signaling pathway may play a crucial role in airway inflammatory responses.
Human Dendritic Cells Stimulated via TLR7 and/or TLR8 Induce the Sequential Production of Il-10, IFN-γ, and IL-17A by Naive CD4+ T Cells
Authors: Lombardi Vincent , Van Overtvelt Laurence , Horiot Stéphane , Moingeon Philippe
Published: March 2009

Depending upon which TLRs are triggered, dendritic cells (DCs) may orient the differentiation of naive CD4+ T cells toward either Th1, Th2, regulatory T cells, or the recently defined Th17 lineage. In this study, we report that a dual stimulation of TLR4 and TLR7/8 with LPS plus R848 leads human monocyte-derived DCs (MoDCs) to produce multiple pro- and anti-inflammatory cytokines, including IL-10, IL-12, and IL-23. Surprisingly, a significant variability in the up-regulation of these cytokines is observed in DCs obtained from various healthy donors, with approximately one of three being “high responders.” High responding MoDCs stimulated via TLR4 and TLR7/8 induce naive allogeneic CD4+ T cell to secrete sequentially IL-10 and IFN-γ, and eventually IL-17A, whereas low responding MoDCs only stimulate IFN-γ production. Both TLR7 and TLR8 play a central role in this phenomenon: TLR4 triggering with LPS up-regulates TLR7 expression on human MoDCs from high responders, silencing of either TLR7 or TLR8 mRNAs inhibits cytokine production in LPS plus R848-treated MoDCs, and plasmacytoid DCs constitutively expressing high levels of TLR7 induce the production of IL-10, IFN-γ, and IL-17A by naive T cells when stimulated with R848 alone. Collectively, our results illustrate the synergy between TLR4 and TLR7/8 in controlling the sequential production of regulatory and proinflammatory cytokines by naive CD4+ T cells. The observed polymorphism in DC responses to such TLR-mediated stimuli could explain differences in the susceptibility to infectious pathogens or autoimmune diseases within the human population.
Chitin Is a Size-Dependent Regulator of Macrophage TNF and IL-10 Production
Authors: Da Silva Carla A. , Chalouni Cécile , Williams Adam , Hartl Dominik , Lee Chun G. , Elias Jack A.
Published: March 2009

Chitin is a ubiquitous polysaccharide in fungi, insects, and parasites. We hypothesized that chitin is a size-dependent regulator of innate immunity. To test this hypothesis, we characterized the effects of chitins of different sizes on murine bronchoalveolar or peritoneal macrophages. In these studies, large chitin fragments were inert, while both intermediate-sized chitin (40–70 μm) and small chitin (SC; <40 μm, largely 2–10 μm) stimulated TNF elaboration. In contrast, only SC induced IL-10 elaboration. The effects of intermediate-sized chitin were mediated by pathways that involve TLR2, dectin-1, and NF-κB. In contrast, the effects of SC were mediated by TLR2-dependent and -independent, dectin-1-dependent pathways that involved the mannose receptor and spleen tyrosine kinase. Chitin contains size-dependent pathogen-associated molecular patterns that stimulate TLR2, dectin-1, and the mannose receptor, differentially activate NF-κB and spleen tyrosine kinase, and stimulate the production of pro- and anti-inflammatory cytokines.
NADPH Oxidase 2 Interaction with TLR2 Is Required for Efficient Innate Immune Responses to Mycobacteria via Cathelicidin Expression
Authors: Yang Chul-Su , Shin Dong-Min , Kim Ki-Hye , Lee Zee-Won , Lee Chul-Ho , Park Sung Goo , Bae Yun Soo , Jo Eun-Kyeong
Published: March 2009

Gp91phox/NADPH oxidase (NOX) 2 is the main catalytic component of NOX, which mediates the phagocytic killing of ingested pathogens via the production of reactive oxygen species (ROS). However, Mycobacterium tuberculosis (Mtb) is relatively resistant to the microbicidal effects of ROS. Thus, the exact roles of NOX2 in the innate immune control against Mtb infection are not fully resolved. In this study, we show that NOX2 is essential for TLR2-dependent inflammatory responses and 1,25-dihydroxyvitamin D3 (1,25D3)-mediated antimicrobial activity against Mtb via cathelicidin expression. NOX2-null macrophages prominently abrogated Mtb-induced ROS production and inflammatory signaling activation in a TLR2-dependent manner. Mtb triggered a physical association between NOX2 and TLR2. In addition, the knockdown of NOX2 inhibited 1,25D3-triggered antimicrobial activity against viable Mtb through the modulation of cathelicidin expression in human macrophages. Treatment of NOX2 knocked down cells with cathelicidin restored the 1,25D3-induced antimicrobial effect, suggesting that the NOX2-dependent induction of cathelicidin in macrophages is part of a defensive strategy against Mtb. Furthermore, cathelicidin expression was required for the Mtb-induced release of ROS and the production of proinflammatory cytokines/chemokines, indicating a positive circuit of inflammation in response to Mtb. Our data collectively demonstrate a novel regulatory mechanism for TLR2-dependent innate responses to Mtb involving crosstalk between NOX2 and TLR2 and the expression of cathelicidin.
IFN-β1a Inhibits the Secretion of Th17-Polarizing Cytokines in Human Dendritic Cells via TLR7 Up-Regulation
Authors: Zhang Xin , Jin Jianping , Tang Yunan , Speer Danielle , Sujkowska Danuta , Markovic-Plese Silva
Published: March 2009

IFN-β, an effective therapy against relapsing-remitting multiple sclerosis, is naturally secreted during the innate immune response against viral pathogens. The objective of this study was to characterize the immunomodulatory mechanisms of IFN-β targeting innate immune response and their effects on dendritic cell (DC)-mediated regulation of T cell differentiation. We found that IFN-β1a in vitro treatment of human monocyte-derived DCs induced the expression of TLR7 and the members of its downstream signaling pathway, including MyD88, IL-1R-associated kinase 4, and TNF receptor-associated factor 6, while it inhibited the expression of IL-1R. Using small interfering RNA TLR7 gene silencing, we confirmed that IFN-β1a-induced changes in MyD88, IL-1R-associated kinase 4, and IL-1R expression were dependent on TLR7. TLR7 expression was also necessary for the IFN-β1a-induced inhibition of IL-1β and IL-23 and the induction of IL-27 secretion by DCs. Supernatant transfer experiments confirmed that IFN-β1a-induced changes in DC cytokine secretion inhibit Th17 cell differentiation as evidenced by the inhibition of retinoic acid-related orphan nuclear hormone receptor C and IL-17A gene expression and IL-17A secretion. Our study has identified a novel therapeutic mechanism of IFN-β1a that selectively targets the autoimmune response in multiple sclerosis.
Modulation of TLR Signaling by Multiple MyD88-Interacting Partners Including Leucine-Rich Repeat Fli-I-Interacting Proteins
Authors: Dai Penggao , Jeong Sun Yong , Yu Yanbao , Leng Taohua , Wu Weidong , Xie Ling , Chen Xian
Published: March 2009

Emerging evidences suggest TLR-mediated signaling is tightly regulated by a specific chain of intracellular protein-protein interactions, some of which are yet to be identified. Previously we utilized a dual-tagging quantitative proteomics approach to uncover MyD88 interactions in LPS-stimulated cells and described the function of Fliih, a leucine-rich repeat (LRR) protein that negatively regulates NF-κB activity. Here we characterize two distinct LRR-binding MyD88 interactors, LRRFIP2 and Flap-1, and found that both are positive regulators of NF-κB activity. Upon LPS stimulation, LRRFIP2 was also found to positively regulate cytokine production in macrophages, suggesting a functional role in TLR4-mediated inflammatory response. Furthermore, we observed that immediately following LPS stimulation both LRRFIP2 and Flap-1 compete with Fliih for interacting with MyD88 to activate the signaling. By using a novel multiplex quantitative proteomic approach, we found that at endogenous levels these positive and negative regulators interact with MyD88 in a timely and orderly manner to differentially mediate the NF-κB activity through the course of signaling from initiation to prolongation, and to repression. Based on these data, we describe a mechanistic model in which selective modulation of TLR signaling is achieved by temporal and dynamic interactions of MyD88 with its regulators.
RhoA GTPase Activation by TLR2 and TLR3 Ligands: Connecting via Src to NF-κB
Authors: Manukyan Maria , Nalbant Perihan , Luxen Sylvia , Hahn Klaus M. , Knaus Ulla G.
Published: March 2009

Rho GTPases are essential regulators of signaling networks emanating from many receptors involved in innate or adaptive immunity. The Rho family member RhoA controls cytoskeletal processes as well as the activity of transcription factors such as NF-κB, C/EBP, and serum response factor. The multifaceted host cell activation triggered by TLRs in response to soluble and particulate microbial structures includes rapid stimulation of RhoA activity. RhoA acts downstream of TLR2 in HEK-TLR2 and monocytic THP-1 cells, but the signaling pathway connecting TLR2 and RhoA is still unknown. It is also not clear if RhoA activation is dependent on a certain TLR adapter. Using lung epithelial cells, we demonstrate TLR2- and TLR3-triggered recruitment and activation of RhoA at receptor-proximal cellular compartments. RhoA activity was dependent on TLR-mediated stimulation of Src family kinases. Both Src family kinases and RhoA were required for NF-κB activation, whereas RhoA was dispensable for type I IFN generation. These results suggest that RhoA plays a role downstream of MyD88-dependent and -independent TLR signaling and acts as a molecular switch downstream of TLR-Src-initiated pathways.
Synergy between Individual TNF-Dependent Functions Determines Granuloma Performance for Controlling Mycobacterium tuberculosis Infection
Authors: Ray J. Christian J. , Flynn JoAnne L. , Kirschner Denise E.
Published: March 2009

Mycobacterium tuberculosis is one of the world’s most deadly human pathogens; an integrated understanding of how it successfully survives in its host is crucial to developing new treatment strategies. One notable characteristic of infection with M. tuberculosis is the formation of granulomas, aggregates of immune cells whose structure and function may reflect success or failure of the host to contain infection. One central regulator of host responses to infection, including granuloma formation, is the pleiotropic cytokine TNF-α. Experimental work has characterized roles for TNF in macrophage activation; regulation of apoptosis; chemokine and cytokine production; and regulation of cellular recruitment via transendothelial migration. Separating the effects of these functions is presently difficult or impossible in vivo. To this end, we applied a computational model to understand specific roles of TNF in control of tuberculosis in a single granuloma. In the model, cells are represented as discrete entities on a spatial grid responding to environmental stimuli by following programmed rules determined from published experimental studies. Simulated granulomas emerge as a result of these rules. After confirming the importance of TNF in this model, we assessed the effects of individual TNF functions. The model predicts that multiple TNF activities contribute to control of infection within the granuloma, with macrophage activation as a key effector mechanism for controlling bacterial growth. Results suggest that bacterial numbers are a strong contributing factor to granuloma structure with TNF. Finally, TNF-dependent apoptosis may reduce inflammation at the cost of impairing mycobacterial clearance.
Class I HLA Folding and Antigen Presentation in β2-Microglobulin-Defective Daudi Cells
Authors: Martayan Aline , Sibilio Leonardo , Tremante Elisa , Monaco Elisa Lo , Mulder Arend , Fruci Doriana , Cova Agata , Rivoltini Licia , Giacomini Patrizio
Published: March 2009

To present virus and tumor Ags, HLA class I molecules undergo a complex multistep assembly involving discrete but transient folding intermediates. The most extensive folding abnormalities occur in cells lacking the class I L chain subunit, called β2-microglobulin (β2m). Herein, this issue was investigated taking advantage of eight conformational murine mAbs (including the prototypic W6/32 mAb) to mapped H chain epitopes of class I molecules, four human mAbs to class I alloantigens, as well as radioimmunoprecipitation, in vitro assembly, pulse-chase, flow cytometry, and peptide-pulse/ELISPOT experiments. We show that endogenous (HLA-A1, -A66, and -B58) as well as transfected (HLA-A2) heavy chains in β2m-defective Burkitt lymphoma Daudi cells are capable of being expressed on the cell surface, although at low levels, and exclusively as immature glycoforms. In addition, HLA-A2 is: 1) partially folded at crucial interfaces with β2m, peptide Ag, and CD8; 2) receptive to exogenous peptide; and 3) capable of presenting exogenous peptide epitopes (from virus and tumor Ags) to cytotoxic T lymphocytes (bulk populations as well as clones) educated in a β2m-positive environment. These experiments demonstrate a precursor-product relationship between novel HLA class I folding intermediates, and define a stepwise mechanism whereby distinct interfaces of the class I H chain undergo successive, ligand-induced folding adjustments in vitro as well as in vivo. Due to this unprecedented class I plasticity, Daudi is the first human cell line in which folding and function of class I HLA molecules are observed in the absence of β2m. These findings bear potential implications for tumor immunotherapy.
T-Independent Antibody Responses to T-Dependent Antigens: A Novel Follicular Dendritic Cell-Dependent Activity
Authors: El Shikh Mohey Eldin M. , El Sayed Rania M. , Szakal Andras K. , Tew John G.
Published: March 2009

Follicular dendritic cells (FDCs) periodically arrange membrane-bound immune complexes (ICs) of T-dependent Ags 200–500Å apart, and in addition to Ag, they provide B cells with costimulatory signals. This prompted the hypothesis that Ag in FDC-ICs can simultaneously cross-link multiple BCRs and induce T cell-independent (TI) B cell activation. TI responses are characterized by rapid IgM production. OVA-IC-bearing FDCs induced OVA-specific IgM in anti-Thy-1-pretreated nude mice and by purified murine and human B cells in vitro within just 48 h. Moreover, nude mice immunized with OVA-ICs exhibited well-developed GL-7+ germinal centers with IC-retaining FDC-reticula and Blimp-1+ plasmablasts within 48 h. In contrast, FDCs with unbound-OVA, which would have free access to BCRs, induced no germinal centers, plasmablasts, or IgM. Engagement of BCRs with rat-anti-mouse IgD (clone 11–26) does not activate B cells even when cross-linked. However, B cells were activated when anti-IgD-ICs, formed with Fc-specific rabbit anti-rat IgG, were loaded on FDCs. B cell activation was indicated by high phosphotyrosine levels in caps and patches, expression of GL-7 and Blimp-1, and B cell proliferation within 48 h after stimulation with IC-bearing FDCs. Moreover, anti-IgD-IC-loaded FDCs induced strong polyclonal IgM responses within 48 h. Blockade of FDC-FcγRIIB inhibited the ability of FDC-ICs to induce T-independent IgM responses. Similarly, neutralizing FDC-C4BP or -BAFF, to minimize these FDC-costimulatory signals, also inhibited this FDC-dependent IgM response. This is the first report of FDC-dependent but TI responses to T cell-dependent Ags.
Characterization of a CD44/CD122int Memory CD8 T Cell Subset Generated under Sterile Inflammatory Conditions
Authors: Mbitikon-Kobo Florentin-Martial , Vocanson Marc , Michallet Marie-Cécile , Tomkowiak Martine , Cottalorda Anne , Angelov Georgi S. , Coupet Charles-Antoine , Djebali Sophia , Marçais Antoine , Dubois Bertrand , Bonnefoy-Bérard Nathalie , Nicolas Jean-François , Arpin Christophe , Marvel Jacqueline
Published: March 2009

Most memory CD8 T cell subsets that have been hitherto defined are generated in response to infectious pathogens. In this study, we have characterized the CD8 T cells that survive priming conditions, devoid of pathogen-derived danger signals. In both a TCR-transgenic model and a model of contact hypersensitivity, we show that the priming of naive CD8 T cells under sterile inflammatory conditions generates memory. The corresponding memory CD8 T cells can be identified by their intermediate expression levels of CD44 and CD122. We also show that CD44/122int memory CD8 T cells spontaneously develop in wild type mice and that they display intermediate levels of several other memory traits including functional (IFN-γ secretion capacity, CCL5 messenger stores), phenotypic, and molecular (T-bet and eomesodermin expression levels) features. We finally show that they correspond to an early differentiation stage and can further differentiate in CD44/122high memory T cells. Altogether, our results identify a new memory CD8 T cell subset that is generated under sterile inflammatory conditions and involved in the recall contact hypersensitivity reactions that are responsible for allergic contact dermatitis.
Two Distinct Populations of H Chain-Edited B Cells Show Differential Surrogate L Chain Dependence
Authors: Nakajima Pamela B. , Kiefer Kerstin , Price Amy , Bosma Gayle C. , Bosma Melvin J.
Published: March 2009

Developing autoreactive B cells may edit (change) their specificity by secondary H or L chain gene rearrangement. Recently, using mice hemizygous for a site-directed VDJH and VJκ transgene (tg) encoding an autoreactive Ab, we reported ongoing L chain editing not only in bone marrow cells with a pre-B/immature B cell phenotype but also in immature/transitional splenic B cells. Using the same transgenic model, we report here that editing at the H chain locus appears to occur exclusively in bone marrow cells with a pro-B phenotype. H chain editing is shown to involve VH replacement at the tg allele or VH rearrangement at the wild-type (wt) allele when the tg is inactivated by nonproductive VH replacement. VH replacement/rearrangement at the tg/wt alleles was found to entail diverse usage of VH genes. Whereas the development of edited B cells expressing the wt allele was dependent on the λ5 component of the surrogate L chain, the development of B cells expressing the tg allele, including those with VH replacement, appeared to be λ5 independent. We suggest that the unique CDR3 region of the tg-encoded μH chain is responsible for the λ5 independence of tg-expressing B cells.
A Central Role for Induced Regulatory T Cells in Tolerance Induction in Experimental Colitis
Authors: Haribhai Dipica , Lin Wen , Edwards Brandon , Ziegelbauer Jennifer , Salzman Nita H. , Carlson Marc R. , Li Shun-Hwa , Simpson Pippa M. , Chatila Talal A. , Williams Calvin B.
Published: March 2009

In addition to thymus-derived or natural T regulatory (nTreg) cells, a second subset of induced T regulatory (iTreg) cells arises de novo from conventional CD4+ T cells in the periphery. The function of iTreg cells in tolerance was examined in a CD45RBhighCD4+ T cell transfer model of colitis. In situ-generated iTreg cells were similar to nTreg cells in their capacity to suppress T cell proliferation in vitro and their absence in vivo accelerated bowel disease. Treatment with nTreg cells resolved the colitis, but only when iTreg cells were also present. Although iTreg cells required Foxp3 for suppressive activity and phenotypic stability, their gene expression profile was distinct from the established nTreg “genetic signature,” indicative of developmental and possibly mechanistic differences. These results identified a functional role for iTreg cells in vivo and demonstrated that both iTreg and nTreg cells can act in concert to maintain tolerance.
Polysaccharide-Protein Complex from Lycium barbarum L. Is a Novel Stimulus of Dendritic Cell Immunogenicity
Authors: Chen Zhisong , Lu Jinhua , Srinivasan Nalini , Tan Benny Kwong Huat , Chan Soh Ha
Published: March 2009

Dendritic cell (DC) immunogenicity correlates with its maturation, which can be induced by toxic microbial products such as LPS. In this study, we report that a nontoxic polysaccharide-protein complex isolated from a Chinese medicinal herb, Lycium barbarum (LBP), induces phenotypic and functional maturation of DCs with strong immunogenicity. LBP up-regulated DC expression of CD40, CD80, CD86, and MHC class II molecules; down-regulated DC uptake of Ag; enhanced DC allostimulatory activity; and induced IL-12p40 and p70 production. All of its five fractions were active. LBP developed enhanced Th1 response, and LBP-treated DCs enhanced Th1 and Th2 responses in vitro and in vivo. Our study provides evidence and rationale on using LBP in various clinical conditions to enhance host immunity and suggests LBP as a potent adjuvant for the design of DC-based vaccines.
The Role of ICOS in Directing T Cell Responses: ICOS-Dependent Induction of T Cell Anergy by Tolerogenic Dendritic Cells
Authors: Tuettenberg Andrea , Huter Eva , Hubo Mario , Horn Julia , Knop Jürgen , Grimbacher Bodo , Kroczek Richard A. , Stoll Sabine , Jonuleit Helmut
Published: March 2009

Tolerogenic dendritic cells (DC) play an important role in maintaining peripheral T cell tolerance in steady-state conditions through induction of anergic, IL-10-producing T cells with suppressive properties. ICOS, an activation-induced member of the CD28 family on T cells, is involved in the induction of IL-10, which itself could contribute to induction of anergy and development of suppressive T cells. Therefore, we analyzed the functional role of ICOS in the differentiation process of human CD4+ T cells upon their interaction with tolerogenic DC. We compared the functional properties of CD4+ T cells from healthy volunteers and ICOS-deficient patients after stimulation with tolerogenic DC. We report that induction of T cell anergy and suppressive capacity is completely blocked after knockdown of ICOS expression in T cells as well as after blocking of ICOS-ICOS ligand interaction in DC/T cell cocultures. Moreover, CD4+ T cells from ICOS-deficient patients were completely resistant to anergy induction and differentiation into suppressive T cells even after supplementation of IL-10. Furthermore, ICOS/ICOS ligand interaction stabilizes IL-10R expression on T cells and thus renders them sensitive to IL-10 effects. Taken together, these results indicate a crucial role for ICOS in the induction of peripheral tolerance maintained by tolerogenic DC mediated mostly via an IL-10-independent mechanism.
CD1d Activation and Blockade: A New Antitumor Strategy
Authors: Teng Michele W. L. , Yue Simon , Sharkey Janelle , Exley Mark A. , Smyth Mark J.
Published: March 2009

CD1d is expressed on APCs and presents glycolipids to CD1d-restricted NKT cells. For the first time, we demonstrate the ability of anti-CD1d mAbs to inhibit the growth of different CD1d-negative experimental carcinomas in mice. Anti-CD1d mAbs systemically activated CD1d+ APC, as measured by production of IFN-γ and IL-12. Tumor growth inhibition was found to be completely dependent on IFN-γ and IL-12 and variably dependent on CD8+ T cells and NK cells, depending upon the tumor model examined. Anti-CD1d mAb induced greater CD8+ T cell-dependent tumor suppression where regulatory CD1d-restricted type II NKT cells have been implicated, and were less effective in a NK cell-dependent manner against tumors where T regulatory cells were immunosuppressive. The ability of anti-CD1d mAbs to coincidently activate CD1d+ APCs to release IL-12 and inhibit CD1d-restricted type II NKT cells makes CD1d an exciting new target for immunotherapy of cancer based on tumor immunoregulation.
B7 Costimulation Is Critical for Host Control of Chronic Mycobacterium tuberculosis Infection
Authors: Bhatt Kamlesh , Uzelac Aleksandra , Mathur Sanjeev , McBride Amanda , Potian Julius , Salgame Padmini
Published: March 2009

Although much is understood regarding the role of B7/CD28 family of costimulatory molecules in regulating host resistance in the context of several pathogens, analogous information with Mycobacterium tuberculosis is lacking. To address the requirements of B7-mediated costimulation in host resistance against tuberculosis, mice deficient in both B7.1 and B7.2 (B7DKO) were aerosol infected with M. tuberculosis Erdman and disease progression was monitored. We report herein that B7DKO mice are initially able to contain the bacterial load in the lung, but exhibit enhanced susceptibility during chronic infection. Despite the early control of bacterial replication, B7DKO mice essentially start off with compromised Th1 immunity and slower granulomatous response in the lung, characterized by markedly reduced lymphocytic infiltration. As the infection progresses from acute phase to the chronic phase, the nascent granulomas in the B7DKO lungs never fully achieve the architecture of granulomas developing in wild-type mice. Instead, lesions spread progressively to involve much of the lung in the B7DKO mice, ultimately leading to necrosis. Thus, early control of M. tuberculosis growth in the lung can occur in the absence of B7 costimulation and is less dependent on Th1 immunity and formation of a granulomatous structure. However, B7 costimulation is critical for long-term containment of infection within lung granulomas. These findings suggest that the use of costimulation-based immunomodulators may have significant repercussions on the induction of host protective immunity against tuberculosis.
ERK5 Knockdown Generates Mouse Leukemia Cells with Low MHC Class I Levels That Activate NK Cells and Block Tumorigenesis
Authors: Charni Seyma , Aguilo Juan Ignacio , Garaude Johan , de Bettignies Geoffroy , Jacquet Chantal , Hipskind Robert A. , Singer Dinah , Anel Alberto , Villalba Martin
Published: March 2009

Tumor cell-based vaccines are currently used in clinical trails, but they are in general poorly immunogenic because they are composed of cell extracts or apoptotic cells. Live tumor cells should be much better Ags provided that they are properly processed by the host immune system. We show herein that stable expression of a small hairpin RNA for ERK5 (shERK5) decreases ERK5 levels in human and mouse leukemic cells and leads to their elimination by NK cells in vivo. The shERK5 cells show down-regulation of MHC class I expression at the plasma membrane. Accordingly, ectopic activation of the ERK5 pathway induces MHC class I gene expression. Coinjection of shERK5-expressing cells into the peritoneum diminishes survival of engrafted wild-type tumor cells. Moreover, s.c. injection of shERK5-expressing cells strongly diminishes tumor development by wild-type cells. Our results show that shERK5 expression in leukemia cells effectively attenuates their tumor activity and allows their use as a tumor cell-based vaccine.
Evolution and Survival of Marine Carnivores Did Not Require a Diversity of Killer Cell Ig-Like Receptors or Ly49 NK Cell Receptors
Authors: Hammond John A. , Guethlein Lisbeth A. , Abi-Rached Laurent , Moesta Achim K. , Parham Peter
Published: March 2009

Ly49 lectin-like receptors and killer cell Ig-like receptors (KIR) are structurally unrelated cell surface glycoproteins that evolved independently to function as diverse NK cell receptors for MHC class I molecules. Comparison of primates and various domesticated animals has shown that species have either a diverse Ly49 or KIR gene family, but not both. In four pinniped species of wild marine carnivore, three seals and one sea lion, we find that Ly49 and KIR are each represented by single, orthologous genes that exhibit little polymorphism and are transcribed to express cell surface protein. Pinnipeds are therefore species in which neither Ly49 nor KIR are polygenic, but retain the ancestral single-copy state. Whereas pinniped Ly49 has been subject to purifying selection, we find evidence for positive selection on KIR3DL during pinniped evolution. This selection, which focused on the D0 domain and the stem, points to the functionality of the KIR and most likely led to the sea lion’s loss of D0. In contrast to the dynamic and rapid evolution of the KIR and Ly49 genes in other species, the pinniped KIR and Ly49 have been remarkably stable during the >33 million years since the last common ancestor of seals and sea lions. These results demonstrate that long-term survival of placental mammal species need not require a diverse system of either Ly49 or KIR NK cell receptors.