bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lymphoepithelial Interactions Trigger Specific Regulation of Gene Expression in the M Cell-Containing Follicle-Associated Epithelium of Peyer’s Patches
Authors: El Bahi Sophia , Caliot Elise , Bens Marcelle , Bogdanova Anna , Kernéis Sophie , Kahn Axel , Vandewalle Alain , Pringault Eric 
Published: April 2014

Abstract
In the intestine, the follicle-associated epithelium (FAE) of Peyer’s patches (PP) performs Ag sampling as the first step in developing immune responses. Depending on the species, this epithelium contains 10–50% of M cells, which act as regulated gates in epithelial barriers that can be used opportunistically by pathogens to invade their host. However, the mechanisms involved in the differentiation and uptake processes of M cells are not known, in part because their limited number in the intestinal mucosa has hampered molecular and biochemical studies. In this work we provide evidence that PP lymphocytes can themselves modulate gene expression in PP in vivo and in an in vitro model of FAE. Transgenic mice carrying a reporter gene under the control of a modified l-pyruvate kinase promoter (SVPK) exhibit strong transgene expression in PP and FAE, but not in the adjacent villous cells. We used the mouse intestinal epithelial cell line m-ICcl2 transfected with the SVPK promoter fused to β-galactosidase to investigate the direct effect of PP lymphocytes on SVPK promoter activity. β-Galactosidase expression was 4.4-fold higher in transfected m-ICcl2 cells when they were cultured with PP lymphocytes. Conversely, green fluorescent protein expression was 1.8-fold lower in stably transfected differentiated intestinal Caco-2cl1 cells with the sucrase isomaltase promoter fused to green fluorescent protein cDNA when they were cultured with PP lymphocytes, indicating that the in vivo FAE down-regulation of sucrase isomaltase promoter is transcriptionally regulated.
I-κB Kinases α and β Have Distinct Roles in Regulating Murine T Cell Function
Authors: Ren Hong , Schmalstieg Aurelia , van Oers Nicolai S. C. , Gaynor Richard B. 
Published: April 2014

AbstractNF-κB is a transcription factor that regulates a variety of genes involved in the control of the immune and inflammatory responses. Activation of NF-κB is mediated by an inducible I-κB kinase (IKK) complex comprised of two catalytic subunits, IKKα and IKKβ. In this study, the role of these kinases in the development and function of T lymphocytes was explored using transgenic mice expressing the dominant-negative forms of one or both kinases under the control of a T cell-specific promoter. Activation of the NF-κB pathway in thymocytes isolated from these transgenic mice following treatment with either PMA and ionomycin or anti-CD3 was markedly inhibited. Although inhibition of IKKα and/or IKKβ function did not alter T cell development in these transgenic mice, the proliferative response to anti-CD3 was reduced in thymocytes isolated from mice expressing dominant-negative IKKβ. However, inhibition of both IKKα and IKKβ was required to markedly reduce cytokine production in thymocytes isolated from these transgenic mice. Finally, we demonstrated that IKKα and IKKβ have opposite roles on the regulation of anti-CD3-induced apoptosis of double-positive thymocytes. These results suggest that IKKα and IKKβ have distinct roles in regulating thymocyte function.
Selective Requirement for CD40-CD154 in Drug-Induced Type 1 Versus Type 2 Responses to Trinitrophenyl-Ovalbumin
Authors: Nierkens Stefan , van Helden Pauline , Bol Marianne , Bleumink Rob , van Kooten Peter , Ramdien-Murli Seema , Boon Louis , Pieters Raymond 
Published: April 2014

AbstractCD154 is transiently expressed by activated T cells and interacts with CD40 on B cells, dendritic cells, macrophages, and monocytes. This costimulatory receptor-ligand couple seems decisive in Ag-driven immune responses but may be differentially involved in type 1 vs type 2 responses. We studied the importance of CD40-CD154 in both responses using the reporter Ag popliteal lymph node assay in which selectively acting drugs generate clearly polarized type 1 (streptozotocin) or type 2 (D-penicillamine, diphenylhydantoin) responses to a constant coinjected Ag in the same mouse strain. Treatment of mice with anti-CD154 reduced characteristic immunological parameters in type 2 responses (B and CD4+ T cell proliferation, IgG1 and IgE Abs, and IL-4 secretion) and only slightly affected the type 1 response (small decrease in IFN-γ production, influx of CD11c+ and F4/80+ cells, and prevention of architectural disruption of the lymph node, but no effect on IgG2a Ab and TNF-α secretion or B and CD4+ T cell proliferation). The findings indicate that the CD40-CD154 costimulatory interaction is a prerequisite in drug-induced type 2 responses and is only marginally involved in type 1 responses. The observed expression patterns of CD80 and CD86 on different APC (B cells in type 2 and dendritic cells in type 1) may be responsible for this discrepancy.
Cells Expressing Indoleamine 2,3-Dioxygenase Inhibit T Cell Responses
Authors: Mellor Andrew L. , Keskin Derin B. , Johnson Theodore , Chandler Phillip , Munn David H. 
Published: April 2014

Abstract
Pharmacological inhibition of indoleamine 2,3-dioxygenase (IDO) activity during murine gestation results in fetal allograft rejection and blocks the ability of murine CD8+ dendritic cells to suppress delayed-type hypersensitivity responses to tumor-associated peptide Ags. These observations suggest that cells expressing IDO inhibit T cell responses in vivo. To directly evaluate the hypothesis that cells expressing IDO inhibit T cell responses, we prepared IDO-transfected cell lines and transgenic mice overexpressing IDO and assessed allogeneic T cell responses in vitro and in vivo. T cells cocultured with IDO-transfected cells did not proliferate but expressed activation markers. The potency of allogeneic T cell responses was reduced significantly when mice were preimmunized with IDO-transfected cells. In addition, adoptive transfer of alloreactive donor T cells yielded reduced numbers of donor T cells when injected into IDO-transgenic recipient mice. These outcomes suggest that genetically enhanced IDO activity inhibited T cell proliferation in vitro and in vivo. Genetic manipulation of IDO activity may be of therapeutic utility in suppressing undesirable T cell responses.
In Vivo CD86 Blockade Inhibits CD4+ T Cell Activation, Whereas CD80 Blockade Potentiates CD8+ T Cell Activation and CTL Effector Function
Authors: Lang Thomas J. , Nguyen Phuong , Peach Robert , Gause William C. , Via Charles S. 
Published: April 2014

AbstractTo address whether a functional dichotomy exists between CD80 and CD86 in naive T cell activation in vivo, we administered anti-CD80 or CD86 blocking mAb alone or in combination to mice with parent-into-F1 graft-vs-host disease (GVHD). In this model, the injection of naive parental T cells into unirradiated F1 mice results in either a Th1 cytokine-driven, cell-mediated immune response (acute GVHD) or a Th2 cytokine-driven, Ab-mediated response (chronic GVHD) in the same F1 recipient. Combined CD80/CD86 blockade beginning at the time of donor cell transfer mimicked previous results seen with CTLA4Ig and completely abrogated either acute or chronic GVHD by preventing the activation and maturation of donor CD4+ T cells as measured by a block in acquisition of memory marker phenotype and cytokine production. Similar results were seen with selective CD86 blockade; however, the degree of CD4 inhibition was always less than that seen with combined CD80/CD86 blockade. A more striking effect was seen with selective CD80 blockade in that chronic GVHD was converted to acute GVHD. This effect was associated with the induction of Th1 cytokine production, donor CD8+ T cell activation, and development of antihost CTL. The similarity of this effect to that reported for selective CTLA4 blockade suggests that CD80 is a critical ligand for CTLA4 in mediating the down-regulation of Th1 responses and CD8+ T cell activation. In contrast, CD86 is critical for the activation of naive CD4+ T cells in either a Th1 or a Th2 cytokine-mediated response.
Suppression of IL-12 Production by Soluble CD40 Ligand: Evidence for Involvement of the p44/42 Mitogen-Activated Protein Kinase Pathway
Authors: Wittmann Miriam , Kienlin Petra , Mommert Susanne , Kapp Alexander , Werfel Thomas 
Published: April 2014

AbstractIL-12 is a key cytokine in skewing immune responses toward Th1-like reactions. Human monocytes/macrophages produce high amounts of bioactive IL-12 when a priming signal (IFN-γ or GM-CSF) precedes a second signal (e.g., LPS). We and others have previously shown that preincubation with LPS before this stimulation procedure can efficiently and selectively suppress the production of IL-12 by human monocytes. In this study, we show that an almost complete suppression of IL-12 production can also be observed after preincubation of monocytes with costimulatory cell surface molecules that bind to members of the TNFR superfamily (CD40 ligand, TNF-related activation-induced cytokine (TRANCE)). The suppression of IL-12 was observable on the mRNA and protein levels and was not due to endogenous production of known IL-12 antagonists (i.e., IL-10, IL-4, and PGE2), to an increased number of cells undergoing apoptosis, nor to down-regulation of the IFN-γ or CD40 receptor. Cell surface expression of the costimulatory molecules CD80 and CD86 was not reduced by the preincubation procedure, and only a moderate reduction of IL-6 production was observed. Several studies have identified signal transduction pathways that are activated by CD40 signaling, including activation of mitogen-activated protein kinases. The presence of the extracellular signal-related kinase-specific mitogen-activated protein kinase kinase 1/2-specific inhibitors PD98059 and U0126 abrogated suppression induced by sCD40 ligand or other second signals. This indicates that activation of extracellular signal-regulated kinase 1/2 contributes to the underlying mechanism of IL-12 suppression. This mechanism may be relevant in other inflammatory responses and may help to develop therapeutic strategies in Th1-mediated diseases.
A Molecular Marker for Thymocyte-Positive Selection: Selection of CD4 Single-Positive Thymocytes with Shorter TCRB CDR3 During T Cell Development
Authors: Yassai Maryam , Ammon Kristin , Goverman Joan , Marrack Phillipa , Naumov Yuri , Gorski Jack 
Published: April 2014

Abstract
The generation of the naive T cell repertoire is a direct result of maturation and selection events in the thymus. Although maturation events are judged predominantly on the expression of surface markers, molecular markers, more intimately involved in the selection process, can be informative. We have identified a molecular marker for selection in later stages of maturation in humans. Thymocytes are selected for the expression of TCR β-chains with shorter CDR3 at the double-positive to single-positive (SP) transition. Here we extend these studies to the mouse and show that the selection phenotype is not related to α-chain pairing but is a function of the MHC haplotype. Interestingly, the selection is much more apparent in CD4 SP thymocytes than in CD8 SP cells. This is in contrast to human thymocytes, where the selection is equally apparent in both lineages. The involvement of MHC in the process argues that this is a positive selection stage. The difference in the extent of this selection between the two SP lineages may indicate a class difference in the nature of the TCR-MHC interaction, the role of coreceptors in the selection process, or both.
Human NK Cell-Mediated Cytotoxicity Triggered by CD86 and Galα1,3-Gal Is Inhibited in Genetically Modified Porcine Cells
Authors: Costa Cristina , Barber Domingo F. , Fodor William L. 
Published: April 2014

AbstractDelayed xenograft rejection is a major hurdle that needs to be addressed to prolong graft survival in pig-to-primate xenotransplantation. NK cell activation has been implicated in delayed xenograft rejection. Both Ab-dependent and independent mechanisms are responsible for the high susceptibility of porcine cells to human NK cell-mediated cytotoxicity. Previous reports demonstrated a role of Galα1,3-Gal Ag in triggering the Ab-independent responses. We hypothesize that expression of CD80 and/or CD86 on porcine cells may also play a role in NK cell activation as human NK cells express a variant of CD28. Our initial analysis showed that porcine endothelial cells and fibroblasts express CD86, but not CD80. Genetic engineering of these cells to express hCD152-hCD59, a chimeric molecule designed to block CD86 in cis, was accompanied by a reduction in susceptibility to human NK cell-mediated cytotoxicity. The use of a specific anti-porcine CD86-blocking Ab and the NK92 and YTS cell lines further confirmed the involvement of CD86 in triggering NK cell-mediated lysis of porcine cells. Maximal protection was achieved when hCD152-hCD59 was expressed in H transferase-transgenic cells, which show reduced Galα1,3-Gal expression. In this work, we describe two mechanisms of human NK cell-mediated rejection of porcine cells and demonstrate that genetically modified cells resist Ab-independent NK cell-mediated cytotoxicity.
The Potency of TCR Signaling Differentially Regulates NFATc/p Activity and Early IL-4 Transcription in Naive CD4+ T Cells
Authors: Brogdon Jennifer L. , Leitenberg David , Bottomly Kim 
Published: April 2014

AbstractThe potency of TCR signaling can regulate the differentiation of naive CD4+ T cells into Th1 and Th2 subsets. In this work we demonstrate that TCR signaling by low-affinity, but not high-affinity, peptide ligands selectively induces IL-4 transcription within 48 h of priming naive CD4+ T cells. This early IL-4 transcription is STAT6 independent and occurs before an increase in GATA-3. Furthermore, the strength of the TCR signal differentially affects the balance of NFATp and NFATc DNA binding activity, thereby regulating IL-4 transcription. Low-potency TCR signals result in high levels of nuclear NFATc and low levels of NFATp, which are permissive for IL-4 transcription. These data provide a model for how the strength of TCR signaling can influence the generation of Th1 and Th2 cells.
Molecular Mechanisms Underlying Differential Contribution of CD28 Versus Non-CD28 Costimulatory Molecules to IL-2 Promoter Activation
Authors: Zhou Xu-Yu , Yashiro-Ohtani Yumi , Nakahira Masakiyo , Park Woong Ryeon , Abe Ryo , Hamaoka Toshiyuki , Naramura Mayumi , Gu Hua , Fujiwara Hiromi 
Published: April 2014

AbstractT cell costimulation via CD28 and other (non-CD28) costimulatory molecules induces comparable levels of [3H]TdR incorporation, but fundamentally differs in the contribution to IL-2 production. In this study, we investigated the molecular basis underlying the difference between CD28 and non-CD28 costimulation for IL-2 gene expression. Resting T cells from a mutant mouse strain generated by replacing the IL-2 gene with a cDNA encoding green fluorescent protein were stimulated with a low dose of anti-CD3 plus anti-CD28 or anti-non-CD28 (CD5 or CD9) mAbs. CD28 and non-CD28 costimulation capable of inducing potent [3H]TdR uptake resulted in high and marginal levels of green fluorescent protein expression, respectively, indicating their differential IL-2 promoter activation. CD28 costimulation exhibited a time-dependent increase in the binding of transcription factors to the NF-AT and NF-κB binding sites and the CD28-responsive element of the IL-2 promoter, whereas non-CD28 costimulation did not. Particularly, a striking difference was observed for the binding of NF-κB to CD28-responsive element and the NF-κB binding site. Decreased NF-κB activation in non-CD28 costimulation resulted from the failure to translocate a critical NF-κB member, c-Rel, to the nuclear compartment due to the lack of IκBβ inactivation. These observations suggest that unlike CD28 costimulation, non-CD28 costimulation fails to sustain IL-2 promoter activation and that such a failure is ascribed largely to the defect in the activation of c-Rel/NF-κB.
Identification of a Candidate Regulatory Region in the HumanCD8Gene Complex by Colocalization of DNase I Hypersensitive Sites and Matrix Attachment Regions Which Bind SATB1 and GATA-3
Authors: Kieffer Lynda J. , Greally John M. , Landres Inna , Nag Shanta , Nakajima Yuko , Kohwi-Shigematsu Terumi , Kavathas Paula B. 
Published: April 2014

AbstractTo locate elements regulating the human CD8 gene complex, we mapped nuclear matrix attachment regions (MARs) and DNase I hypersensitive (HS) sites over a 100-kb region that included the CD8B gene, the intergenic region, and the CD8A gene. MARs facilitate long-range chromatin remodeling required for enhancer activity and have been found closely linked to several lymphoid enhancers. Within the human CD8 gene complex, we identified six DNase HS clusters, four strong MARs, and several weaker MARs. Three of the strong MARs were closely linked to two tissue-specific DNase HS clusters (III and IV) at the 3′ end of the CD8B gene. To further establish the importance of this region, we obtained 19 kb of sequence and screened for potential binding sites for the MAR-binding protein, SATB1, and for GATA-3, both of which are critical for T cell development. By gel shift analysis we identified two strong SATB1 binding sites, located 4.5 kb apart, in strong MARs. We also detected strong GATA-3 binding to an oligonucleotide containing two GATA-3 motifs located at an HS site in cluster IV. This clustering of DNase HS sites and MARs capable of binding SATB1 and GATA-3 at the 3′ end of the CD8B gene suggests that this region is an epigenetic regulator of CD8 expression.
Detailed Analysis of CD4+ Th Responses to Envelope and Gag Proteins of Simian Immunodeficiency Virus Reveals an Exclusion of Broadly Reactive Th Epitopes from the Glycosylated Regions of Envelope
Authors: Sarkar Surojit , Kalia Vandana , Murphey-Corb Michael , Montelaro Ronald C. 
Published: April 2014

Abstract
Ag-specific CD4+ Th cells play a key role in the development, maturation, and maintenance of pathogen-specific humoral and cellular immune responses. To define the fine specificity of broadly reactive Th responses associated with mature immunity in a lentiviral system, we analyzed peptide-specific Th responses in eight macaques chronically infected with a reference live attenuated SIV at 12–14 mo postinoculation. All macaques had stable immunocompetent Th cells at the time of analysis, and a unique array of Th responses to 20-mer overlapping peptides from envelope (Env) and Gag was identified for each macaque, which were then used to define a set of 31 broadly reactive peptide epitopes. Only 5 of the 31 broadly reactive Th epitope peptides mapped to the surface (SU) domain of Env. Interestingly, these were all confined to two conserved nonglycosylated regions toward the carboxyl terminus of SU, suggesting a structural influence of glycosylation on development of Th responses. Gag and the Env transmembrane proteins contained the majority of broadly reactive peptide epitopes (12 and 14 peptides, respectively), which were uniformly distributed throughout their sequence. This study defines for the first time broadly reactive Th epitope peptides of SIV Env and Gag proteins that are associated with enduring broadly protective vaccine immunity to attenuated SIV, which may be used for the design and evaluation of experimental vaccines. Moreover, the data suggest that extensive glycosylation of SU may provide yet another immune escape mechanism developed by lentiviruses to restrict the breadth of Th repertoire to SU, a major immunologically exposed protein of the virus.
Two Lipoproteins Extracted fromEscherichia coliK-12 LCD25 Lipopolysaccharide Are the Major Components Responsible for Toll-Like Receptor 2-Mediated Signaling
Authors: Lee Hyun-Ku , Lee Jongdae , Tobias Peter S. 
Published: April 2014

AbstractToll-like receptor 2 (TLR2)-mediated cell activation induced by commercial preparations of LPS was recently shown to arise from impurities whose identities are not known. In this work, we determined the molecules responsible for TLR2-mediated cell activation in LPS derived from Escherichia coli K-12 strain LCD25. When LCD25 LPS was phenol extracted, two proteins capable of TLR2-mediated cell activation were purified and identified as E. coli lipoproteins. We cloned, expressed, and purified these two lipoproteins, Lip19 and Lip12. Lip19 or Lip12 activated TNF-α production from RAW264.7 and THP-1 cells in a TLR2-dependent manner. However, neither Lip19 nor Lip12 activated HUVECs, which lack endogenous TLR2. Additionally, IκB kinase β and c-Jun N-terminal kinase 1 activation in THP-1 cells induced by Lip19 or Lip12 was observed. TLR2 activation by Lip19 and Lip12 in HEK293 cells was blocked by inhibitory anti-TLR2 mAbs. The unlipidated mutants, Lip19-C19S and Lip12-C21S, in which the NH2-terminal cysteine was substituted by serine, lost their ability to activate TLR2-transfected HEK 293 cells. Taken together, these results demonstrate that two lipoproteins constitute the major contaminants responsible for TLR2-mediated cell activation in E. coli LCD25 LPS.
Leptin-Deficient Mice Exhibit Impaired Host Defense in Gram-Negative Pneumonia
Authors: Mancuso Peter , Gottschalk Andrew , Phare Susan M. , Peters-Golden Marc , Lukacs Nicholas W. , Huffnagle Gary B. 
Published: April 2014

AbstractLeptin is an adipocyte-derived hormone that is secreted in correlation with total body lipid stores. Serum leptin levels are lowered by the loss of body fat mass that would accompany starvation and malnutrition. Recently, leptin has been shown to modulate innate immune responses such as macrophage phagocytosis and cytokine synthesis in vitro. To determine whether leptin plays a role in the innate host response against Gram-negative pneumonia in vivo, we compared the responses of leptin-deficient and wild-type mice following an intratracheal challenge of Klebsiella pneumoniae. Following K. pneumoniae administration, we observed increased leptin levels in serum, bronchoalveolar lavage fluid, and whole lung homogenates. In a survival study, leptin-deficient mice, as compared with wild-type mice, exhibited increased mortality following K. pneumoniae administration. The increased susceptibility to K. pneumoniae in the leptin-deficient mice was associated with reduced bacterial clearance and defective alveolar macrophage phagocytosis in vitro. The exogenous addition of very high levels of leptin (500 ng/ml) restored the defect in alveolar macrophage phagocytosis of K. pneumoniae in vitro. While there were no differences between wild-type and leptin-deficient mice in lung homogenate cytokines TNF-α, IL-12, or macrophage-inflammatory protein-2 after K. pneumoniae administration, leukotriene synthesis in lung macrophages from leptin-deficient mice was reduced. Leukotriene production was restored by the addition of exogenous leptin (500 ng/ml) to macrophages in vitro. This study demonstrates for the first time that leptin-deficient mice display impaired host defense in bacterial pneumonia that may be due to a defect in alveolar macrophage phagocytosis and leukotriene synthesis.