bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stromal Cell-Derived Factor 1 (CXCL12) Induces Human Cell Migration into Human Lymph Nodes Transplanted into SCID Mice
Authors: Blades Mark C. , Manzo Antonio , Ingegnoli Francesca , Taylor Peter R. , Panayi Gabriel S. , Irjala Heikki , Jalkanen Sirpa , Haskard Dorian O. , Perretti Mauro , Pitzalis Costantino 
Published: April 2014

Abstract
Stromal cell-derived factor 1 (SDF-1; CXCL12), a CXC chemokine, has a primary role in signaling the recruitment of hemopoietic stem cell precursors to the bone marrow during embryonic development. In postnatal life, SDF-1 is widely expressed and is induced in chronically inflamed tissues such as psoriatic skin and the rheumatoid synovium, but has also been implicated in the migration of lymphocytes to lymphoid organs. To investigate the role of SDF-1 in recirculation and homing in vivo, we have developed a model in which human peripheral lymph nodes (huPLN) are transplanted into SCID mice. We have shown that huPLN transplants are viable, vascularized by the murine circulation that forms functional anastomoses with transplant vessels. In addition, grafts retain some features of the pretransplantation tissue, such as lymphoid follicles, lymphatic and high endothelial venule markers. We also show that SDF-1 is capable of inducing the migration of a SDF-1-responsive cell line (U937) and human PBLs from the murine circulation into the grafts in a dose-dependant manner, inhibitable by CXCR4 blockade. The mechanism of action of SDF-1 in this model is independent from that of TNF-α and does not rely on the up-regulation of adhesion molecules (such as ICAM-1) on the graft vascular endothelium. This is the first description of huPLN transplantation into SCID mice and of the functional effects of SDF-1 in regard to the migration of human cells into huPLN in vivo. This model provides a powerful tool to investigate the pathways involved in cell migration into lymphoid organs and potentially to target them for therapeutic purposes.
Orally Tolerized T Cells Are Only Able to Enter B Cell Follicles Following Challenge with Antigen in Adjuvant, but They Remain Unable to Provide B Cell Help
Authors: Smith Karen M. , McAskill Fiona , Garside Paul 
Published: April 2014

Abstract
Although it is well documented that feeding Ag can tolerize or prime systemic humoral and cell-mediated immune responses, the mechanisms involved remain unclear. Elucidation of these mechanisms remains, in part, complicated by the inability to assess responses by individual lymphocyte populations. In the past, in vivo studies have examined T cell responses at the gross level by examining their ability to support B cell Ab production. However, as the fed Ag has the capacity to affect B cells directly, analyzing the functional capacity of a single Ag-specific T cell population in vivo has been difficult. Using a double-adoptive transfer system, we have primed or tolerized T cells, independently of B cells with a high dose of fed Ag, and examined the ability of these primed or tolerized T cells to support B cell clonal expansion in response to a conjugated Ag in vivo. We have been able to show that primed T cells support B cell clonal expansion and Ab production whereas tolerized T cells do not. Thus, we have provided direct evidence that tolerized T cells are functionally unable to help B cells in vivo. Furthermore, we have shown that this inability of tolerized T cells to support fulminant B cell responses is not a result of defective clonal expansion or follicular migration, since following challenge tolerized T cells are similar to primed T cells in both of these functions.
Fibroblasts from Human Spleen Regulate NK Cell Differentiation from Blood CD34+ Progenitors Via Cell Surface IL-15
Authors: Briard Diane , Brouty-Boyé Danièle , Azzarone Bruno , Jasmin Claude 
Published: April 2014

Abstract
Besides a structural role in tissue architecture, fibroblasts have been shown to regulate the proliferation and differentiation of other neighboring specialized cell types, but differently according to the anatomic site and pathologic status of their tissue of origin. In this study we report a novel regulatory function of human spleen-derived fibroblasts in the development of NK cells from adult resting blood progenitors. When CD34+ cells were cocultured with spleen-derived fibroblasts in monolayers, nonadherent CD56+CD3− NK cells were predominantly produced after 2–3 wk of culture in the absence of exogenous cytokines. Most NK cells expressed class I-recognizing CD94 and NK p46, p44, and p30 receptors as well as perforin and granzyme lytic granules. Moreover, these cells demonstrated spontaneous killing activity. Cell surface immunophenotyping of spleen-derived fibroblasts revealed a low and consistent expression of IL-15, Flt3 ligand, and c-kit ligand. Additionally, low picogram amounts of the three cytokines were produced extracellularly. Neutralizing Abs to IL-15, but not the other two ligands, blocked NK cell development. Additionally, suppressing direct contacts of CD34+ progenitors and fibroblasts by microporous membrane abrogated NK cell production. We conclude that stromal fibroblasts within the human spleen are involved via constitutive cell surface expression of bioactive IL-15 in the development of functional activated NK cells under physiologic conditions.
Prostanoids Play a Major Role in the Primary Tumor-Induced Inhibition of Dendritic Cell Differentiation
Authors: Sombroek Claudia C. , Stam Anita G. M. , Masterson Allan J. , Lougheed Sinéad M. , Schakel Marcel J. A. G. , Meijer Chris J. L. M. , Pinedo Herbert M. , van den Eertwegh Alfons J. M. , Scheper Rik J. , de Gruijl Tanja D. 
Published: April 2014

Abstract
Production of immunosuppressive factors is one of the mechanisms by which tumors evade immunosurveillance. Soluble factors hampering dendritic cell (DC) development have recently been identified in culture supernatants derived from tumor cell lines. In this study, we investigated the presence of such factors in 24-h culture supernatants from freshly excised solid human tumors (colon, breast, renal cell carcinoma, and melanoma). While primary tumor-derived supernatant (TDSN) profoundly hampered the in vitro DC differentiation from CD14+ plastic-adherent monocytes or CD34+ precursors (based on morphology and CD1a/CD14 phenotype), the effects of tested tumor cell line-derived supernatants were minor. Cyclooxygenase (COX)-1- and COX-2-regulated prostanoids present in the primary TDSN were found to be solely responsible for the observed hampered differentiation of monocyte-derived DC (MoDC). In contrast, both prostanoids and IL-6 were found to contribute to the TDSN-induced inhibition of DC differentiation from CD34+ precursor cells. While the addition of TDSN during differentiation interfered with the ability of CD34-derived DC to stimulate a primary allogeneic T cell response, it actually increased this ability of MoDC. These opposite effects were correlated to different effects of the TDSN on the expression levels of CD86 and HLA-DR on the DC from the different precursor origins. Although TDSN increased the T cell-stimulatory capacity of MoDC, TDSN inhibited the IL-12 production and increased the IL-10 production of MoDC, thus skewing them to a type-2 T cell-inducing phenotype. In conclusion, this study demonstrates that primary tumors negatively impact DC development and function through COX-1 and -2 regulated factors, whereas tumor-derived cell lines may lose this ability upon in vitro propagation.
Transmodulation of BCR Signaling by Transduction- Incompetent Antigen Receptors: Implications for Impaired Signaling in Anergic B Cells
Authors: Vilen Barbara J. , Burke Kathy M. , Sleater Michelle , Cambier John C. 
Published: April 2014

Abstract
B cell tolerance can be maintained by functional inactivation, or anergy, wherein B cell Ag receptors (BCR) remain capable of binding Ag, but are unable to transduce signals. Although the molecular mechanisms underlying this unresponsiveness are unknown, some models of B cell anergy are characterized by disruption of proximal BCR signaling events, and by destabilization of the BCR complex. Receptor destabilization is manifest by a reduced ability to coimmunoprecipitate membrane Ig with the Ig-α/Ig-β signal-transducing complex. To begin to explore the possibility that anergy is the consequence of receptor destabilization, we analyzed a panel of B lymphoma transfectants expressing constant amounts of signal-competent Ag receptors and varied amounts of a receptor with identical specificity, but bearing mutations that render it incapable of interacting with Ig-α/Ig-β. This analysis revealed that coaggregation of signal-incompetent receptors prevented Ag-induced Ig-α and Syk phosphorylation, mobilization of Ca2+, and the up-regulation of CD69 mediated by competent receptors. In contrast, Ag-induced Cbl and Erk phosphorylation were unaffected. Data indicate that coaggregation of destabilized receptors (as few as ∼15% of total) with signal-competent receptors significantly affects the ability of competent receptors to transduce signals. Thus, BCR destabilization may underlie the Ag unresponsiveness of anergic B cells.
T Cell-Dependent Maturation of Dendritic Cells in Response to Bacterial Superantigens
Authors: Muraille Eric , De Trez Carl , Pajak Bernard , Brait Maryse , Urbain Jacques , Leo Oberdan 
Published: April 2014

AbstractDendritic cells (DC) express a set of germline-encoded transmembrane Toll-like receptors that recognize shared microbial products, such as Escherichia coli LPS, termed pathogen-associated molecular patterns. Analysis of the in vivo response to pathogen-associated molecular patterns has uncovered their ability to induce the migration and the maturation of DC, favoring thus the delivery of Ag and costimulatory signals to naive T cells in vivo. Bacterial superantigens constitute a particular class of pathogen-derived molecules known to induce a potent inflammatory response in vivo, secondary to the activation of a large repertoire of T cells. We demonstrate in this work that Staphylococcal superantigens induce migration and maturation of DC populations in vivo. However, in contrast to LPS, superantigens failed to induce DC maturation in RAG or MHC class II-deficient mice, suggesting that T cell activation was a prerequisite for DC maturation. This conclusion was further supported by the finding that T cell activation induced by 1) mitogenic anti-CD3 mAbs, 2) allo-MHC determinants, or 3) nominal Ag in a TCR-transgenic model induces DC maturation in vivo. These studies also revealed that DC that matured in response to T cell mitogens display, comparatively to LPS, a distinctive phenotype characterized by high expression of the MHC class II, CD40, and CD205 markers, but only moderate (CD86) to minimal (CD80) expression of CD28/CTLA4 ligands. This work demonstrates that activation of a sufficient number of naive T cells in vivo constitutes a novel form of immune danger, functionally linked to DC maturation.
Matrix Metalloproteinases 9 and 2 Are Necessary for the Migration of Langerhans Cells and Dermal Dendritic Cells from Human and Murine Skin
Authors: Ratzinger Gudrun , Stoitzner Patrizia , Ebner Susanne , Lutz Manfred B. , Layton Guy T. , Rainer Christian , Senior Robert M. , Shipley J. Michael , Fritsch Peter , Schuler Gerold , Romani Nikolaus 
Published: April 2014

AbstractDendritic cells migrate from the skin to the draining lymph nodes. They transport immunogenic MHC-peptide complexes, present them to Ag-specific T cells in the T areas, and thus generate immunity. Migrating dendritic cells encounter physical obstacles, such as basement membranes and collagen meshwork. Prior work has revealed that matrix metalloproteinase-9 (MMP-9) contributes to mouse Langerhans cell migration. In this study, we use mouse and human skin explant culture models to further study the role of MMPs in the migration and maturation of skin dendritic cells. We found that MMP-2 and MMP-9 are expressed on the surface of dendritic cells from the skin, but not from other sources. They are also expressed in migrating Langerhans cells in situ. The migration of both Langerhans cells and dermal dendritic cells is inhibited by a broad spectrum inhibitor of MMPs (BB-3103), by Abs to MMP-9 and -2, and by the natural tissue inhibitors of metalloproteinases (TIMP), TIMP-1 and TIMP-2. Inhibition by anti-MMP-2 and TIMP-2 define a functional role for MMP-2 in addition to the previously described function of MMP-9. The importance of MMP-9 was emphasized using MMP-9-deficient mice in which Langerhans cell migration from skin explants was strikingly reduced. However, MMP-9 was only required for Langerhans cell migration and not maturation, since nonmigrating Langerhans cells isolated from the epidermis matured normally with regard to morphology, phenotype, and T cell stimulatory function. These data underscore the importance of MMPs, and they may be of relevance for therapeutically regulating dendritic cell migration in clinical vaccination approaches.
Contrasting the Roles of Costimulation and the Natural Adjuvant Lipopolysaccharide During the Induction of T Cell Immunity
Authors: Maxwell Joseph R. , Ruby Carl , Kerkvliet Nancy I. , Vella Anthony T. 
Published: April 2014

Abstract
The requirements for circumventing tolerance induction in favor of memory T cell development are poorly understood. Although two signals (Ag and costimulation) are necessary to drive effective T cell clonal expansion, few memory T cells remain after the response wanes. The adjuvant LPS can increase numbers of long-lived Ag-specific T cells, but its mechanism of action is not understood. In this report, it is shown that LPS, when combined with two-signal stimulation, profoundly enhances T cell survival in vivo. This survival does not appear to be dependent on the cytokines TNF-α, IL-1β, IL-6, and IFN-γ, nor is it dependent on the transcription factor NF-κB. However, in vivo proliferation of NF-κB-deficient T cells was comparable to that of wild-type T cells, yet their early accumulation in the lymph nodes was severely reduced unless the mice were treated with LPS and an agonistic CD40 mAb. Most importantly, we found that activation of two different costimulatory signals, CD40 and OX40, could not substitute for LPS in rescuing T cells from peripheral deletion. Perhaps surprisingly, these data show that LPS delivers a qualitatively different signal than multiple costimulatory signals.
On CD28/CD40 Ligand Costimulation, Common γ-Chain Signals, and the Alloimmune Response
Authors: Demirci Gülçin , Gao Wenda , Zheng Xin Xiao , Malek Thomas R. , Strom Terry B. , Li Xian Chang 
Published: April 2014

Abstract
Activation and robust expansion of naive T cells often require T cell costimulatory signals and T cell growth factors. However, the precise growth and costimulation requirements for activation and expansion of CD4+ and CD8+ T cells in vivo in allograft response are still not clearly defined. In the present study, we critically examined the role of CD28/CD40 ligand (CD40L) costimulation and the common γ-chain (γc) signals, a shared signaling component by receptors for all known T cell growth factors (i.e., IL-2, IL-4, IL-7, IL-9, IL-15, IL-21), in activation and expansion of CD4+ and CD8+ T cells in the allogeneic hosts. We found that CD28/CD40L costimulation and the γc signals are differentially involved in proliferation and clonal expansion of CD4+ and CD8+ T cells in response to alloantigen stimulation. CD8+ T cells are highly dependent on the γc signals for survival, expansion, and functional maturation, whereas in vivo expansion of alloreactive CD4+ T cells is largely γc independent. T cell costimulation via CD28 and CD40L, however, is necessary and sufficient for activation and expansion of CD4+ T cells in vivo. In a skin transplant model, blocking both CD28/CD40L and the γc pathways induced prolonged skin allograft survival. Our study provides critical insights that the CD4 and CD8 compartments are most likely governed by distinct mechanisms in vivo, and targeting both costimulatory and γc signals may be highly effective in certain cytopathic conditions involving activation of both CD4+ and CD8+ T cells.
Competition Between CTL Narrows the Immune Response Induced by Prime-Boost Vaccination Protocols
Authors: Palmowski Michael J. , Choi Ed Man-Lik , Hermans Ian F. , Gilbert Sarah C. , Chen Ji-Li , Gileadi Uzi , Salio Mariolina , Van Pel Aline , Man Stephen , Bonin Eivor , Liljestrom Peter , Dunbar P. Rod , Cerundolo Vincenzo 
Published: April 2014

AbstractRecombinant vaccines encoding strings of virus- or tumor-derived peptides and/or proteins are currently being designed for use against both cancer and infectious diseases. These vaccines aim to induce cytotoxic immune responses against several Ags simultaneously. We developed a novel tetramer-based technique, based on chimeric HLA A2/H-2Kb H chains, to directly monitor the CTL response to such vaccines in HLA-A2 transgenic mice. We found that priming and boosting with the same polyepitope construct induced immune responses that were dominated by CTL of a single specificity. When a mixture of viruses encoding single proteins was used to boost the polyepitope primed response, CTL of multiple specificities were simultaneously expanded to highly effective levels in vivo. In addition, we show that a preexisting response to one of the epitopes encoded within a polyepitope construct significantly impaired the ability of the vaccine to expand CTL of other specificities. Our findings define a novel vaccination strategy optimized for the induction of an effective polyvalent cytotoxic response.
Generation of CD4+CD25+ Regulatory T Cells from Autoreactive T Cells Simultaneously with Their Negative Selection in the Thymus and from Nonautoreactive T Cells by Endogenous TCR Expression
Authors: Kawahata Kimito , Misaki Yoshikata , Yamauchi Michiko , Tsunekawa Shinji , Setoguchi Keigo , Miyazaki Jun-ichi , Yamamoto Kazuhiko 
Published: April 2014

Abstract
Normal T cell repertoire contains regulatory T cells that control autoimmune responses in the periphery. One recent study demonstrated that CD4+CD25+ T cells were generated from autoreactive T cells without negative selection. However, it is unclear whether, in general, positive selection and negative selection of autoreactive T cells are mutually exclusive processes in the thymus. To investigate the ontogeny of CD4+CD25+ regulatory T cells, neo-autoantigen-bearing transgenic mice expressing chicken egg OVA systemically in the nuclei (Ld-nOVA) were crossed with transgenic mice expressing an OVA-specific TCR (DO11.10). Ld-nOVA × DO11.10 mice had increased numbers of CD4+CD25+ regulatory T cells in the thymus and the periphery despite clonal deletion. In Ld-nOVA × DO11.10 mice, T cells expressing endogenous TCR αβ chains were CD4+CD25− T cells, whereas T cells expressing autoreactive TCR were selected as CD4+CD25+ T cells, which were exclusively dominant in recombination-activating gene 2-deficient Ld-nOVA × DO11.10 mice. In contrast, in DO11.10 mice, CD4+CD25+ T cells expressed endogenous TCR αβ chains, which disappeared in recombination-activating gene 2-deficient DO11.10 mice. These results indicate that part of autoreactive T cells that have a high affinity TCR enough to cause clonal deletion could be positively selected as CD4+CD25+ T cells in the thymus. Furthermore, it is suggested that endogenous TCR gene rearrangement might critically contribute to the generation of CD4+CD25+ T cells from nonautoreactive T cell repertoire, at least under the limited conditions such as TCR-transgenic models, as well as the generation of CD4+CD25− T cells from autoreactive T cell repertoire.
NF-κB2 Is Required for Optimal CD40-Induced IL-12 Production but Dispensable for Th1 Cell Differentiation
Authors: Speirs Kendra , Caamano Jorge , Goldschmidt Michael H. , Hunter Christopher A. , Scott Phillip 
Published: April 2014

Abstract
NF-κB is a ubiquitously expressed transcription factor involved in the regulation of innate and adaptive immunity. As part of studies to define the role of various NF-κB family members in Th cell development and maintenance, we infected NF-κB2−/− and control mice with Leishmania major and followed disease progression. NF-κB2−/− mice on a normally resistant background develop chronic nonhealing lesions associated with uncontrolled parasite replication and a failure to develop an IFN-γ response. We show that there are no intrinsic defects in Th cell differentiation in the absence of NF-κB2. Indeed, NF-κB2−/− T cells are able to develop a Th1 phenotype and protect recombination-activating gene−/− mice from progressive cutaneous leishmaniasis. We demonstrate instead that the susceptibility of NF-κB2−/− mice to L. major is the result of an IL-12 deficiency, and we provide evidence for a specific impairment in CD40-induced IL-12 production by macrophages lacking this transcription factor.
Aberrant Expression of Fas Ligand in Mice Deficient for the MHC Class II Transactivator
Authors: Gourley Tania S. , Patel Dipak R. , Nickerson Kevin , Hong Soon-Cheol , Chang Cheong-Hee 
Published: April 2014

Abstract
The MHC class II transactivator (CIITA) is a critical regulator of MHC class II genes and other genes involved in the Ag presentation pathway. CIITA-deficient mice lack MHC class II expression on almost all APCs. In this study, we show that these mice also have aberrant Fas ligand expression on both CD4 T cells and B cells. We found that Fas ligand expression was greatly increased on CIITA-deficient CD4 T cells during the Th1 differentiation process. However, both CIITA-deficient and control Th1 effector cells up-regulated Fas ligand to similar levels if cells were reactivated. The introduction of CIITA into primary CD4 T cells via retroviral infection resulted in a reduction in the level of Fas ligand and delay in apoptosis after activation. Interestingly, activated B cells from the CIITA-deficient mice also showed increased levels of Fas ligand that could be to some degree inhibited by the introduction of IL-4.
CTLA-4 Suppresses Proximal TCR Signaling in Resting Human CD4+ T Cells by Inhibiting ZAP-70 Tyr319 Phosphorylation: A Potential Role for Tyrosine Phosphatases
Authors: Guntermann Christine , Alexander Denis R. 
Published: April 2014

AbstractThe balance between positive and negative signals plays a key role in determining T cell function. CTL-associated Ag-4 is a surface receptor that can inhibit T cell responses induced upon stimulation of the TCR and its CD28 coreceptor. Little is known regarding the signaling mechanisms elicited by CTLA-4. In this study we analyzed CTLA-4-mediated inhibition of TCR signaling in primary resting human CD4+ T cells displaying low, but detectable, CTLA-4 cell surface expression. CTLA-4 coligation with the TCR resulted in reduced downstream protein tyrosine phosphorylation of signaling effectors and a striking inhibition of extracellular signal-regulated kinase 1/2 activation. Analysis of proximal TCR signaling revealed that TCR ζ-chain phosphorylation and subsequent ζ-associated protein of 70 kDa (ZAP-70) tyrosine kinase recruitment were not significantly affected by CTLA-4 engagement. However, the association of p56lck with ZAP-70 was inhibited following CTLA-4 ligation, correlating with reduced actions of p56lck in the ZAP-70 immunocomplex. Moreover, CTLA-4 ligation caused the selective inhibition of CD3-mediated phosphorylation of the positive regulatory ZAP-70 Y319 site. In addition, we demonstrate protein tyrosine phosphatase activity associated with the phosphorylated CTLA-4 cytoplasmic tail. The major phosphatase activity was attributed to Src homology protein 2 domain-containing tyrosine phosphatase 1, a protein tyrosine phosphatase that has been shown to be a negative regulator of multiple signaling pathways in hemopoietic cells. Collectively, our findings suggest that CTLA-4 can act early during the immune response to regulate the threshold of T cell activation.