bluuebunny/crossref_metadata_2025 huggingface dataset:
Homeostatic Proliferation of a Qa-1b-Restricted T Cell: A Distinction between the Ligands Required for Positive Selection and for Proliferation in Lymphopenic Hosts
Authors: Sullivan Barbara A. , Reed-Loisel Lisa M. , Kersh Gilbert J. , Jensen Peter E.
Published: April 2014

Naive T cells proliferate in response to self MHC molecules after transfer into lymphopenic hosts, a process that has been termed homeostatic proliferation (HP). Previous studies have demonstrated that HP is driven by low level signaling induced by interactions with the same MHC molecules responsible for positive selection in the thymus. Little is known about the homeostatic regulation of T cells specific for class Ib molecules, including Qa-1 and H2-M3, though it has been suggested that their capacity to undergo homeostatic expansion may be inherently limited. In this study, we demonstrate that naive 6C5 TCR transgenic T cells with specificity for Qa-1b have a capacity similar to conventional T cells to undergo HP after transfer into sublethally irradiated mice. Proliferation was largely dependent on the expression of β2-microglobulin, and experiments with congenic recipients expressing Qa-1a instead of Qa-1b demonstrated that HP is specifically driven by Qa-1b and not through cross-recognition of classical class I molecules. Thus, the same MHC molecule that mediates positive selection of 6C5 T cells is also required for HP. Homeostatic expansion, like positive selection, occurs in the absence of a Qa-1 determinant modifier, the dominant self-peptide bound to Qa-1 molecules. However, experiments with TAP−/− recipients demonstrate a clear distinction between the ligand requirements for thymic selection and HP. Positive selection of 6C5 T cells is dependent on TAP function, thus selection is presumably mediated by TAP-dependent peptides. By contrast, HP occurs in TAP−/− recipients, providing an example where the ligand requirements for HP are less stringent than for thymic selection.
Negative Regulation of NK Cell Activities by Inhibitory Receptor CD94/NKG2A Leads to Altered NK Cell-Induced Modulation of Dendritic Cell Functions in Chronic Hepatitis C Virus Infection
Authors: Jinushi Masahisa , Takehara Tetsuo , Tatsumi Tomohide , Kanto Tatsuya , Miyagi Takuya , Suzuki Takahiro , Kanazawa Yoshiyuki , Hiramatsu Naoki , Hayashi Norio
Published: April 2014

NK cells are potent activators of dendritic cells (DCs), but it remains obscure how third-party cells affect the ability of NK cells to modulate DC functions. We show here that NK cells derived from healthy donors (N-NK), when cocultured with human liver epithelial cells, induced maturation as well as activation of DCs, such as increased migratory capacity as well as T cell stimulatory activity. In contrast, NK cells from chronic hepatitis C virus-infected donors (HCV-NK) were not capable of activating DCs under the same conditions. In comparison to N-NK, HCV-NK showed higher expression of CD94/NKG2A and produced IL-10 and TGFβ when cultured with hepatic cells, most of which express HLA-E, a ligand for CD94/NKG2A. Blockade of NKG2A restored the ability of HCV-NK to activate DCs, which appeared to result from the reduced NK cell production of IL-10 and TGFβ. The blockade also endowed HCV-NK with an ability to drive DCs to generate Th1-polarized CD4+ T cells. These findings show that NK cell modulation of DCs is regulated by third-party cells through NK receptor and its ligand interaction. Aberrant expression of NK receptors may have an impact on the magnitude and direction of DC activation of T cells under pathological conditions, such as chronic viral infection.
Expression and Characterization of a Novel CD6 Ligand in Cells Derived from Joint and Epithelial Tissues
Authors: Saifullah Mohammad K. , Fox David A. , Sarkar Sujata , Abidi Syed M. A. , Endres Judith , Piktel Joseph , Haqqi Tariq M. , Singer Nora G.
Published: April 2014

CD6 is a T cell surface glycoprotein that plays an important role in interactions of thymocytes with thymic epithelial cells and in mature T cell interactions with selected nonprofessional tissue APCs. We describe a novel CD6 ligand (CD6L) 3A11 Ag that is distinct from the known CD6L (CD166). The 3A11 protein is expressed on cells derived from human thymus, skin, synovium, and cartilage, and its expression is enhanced by IFN-γ. mAbs directed against the 3A11 Ag and CD166 exhibit distinct patterns of binding to a panel of cell lines. Confocal microscopy shows that both CD166 and the 3A11 Ag are expressed at the cell surface, and that these proteins colocalize. The 3A11 Ag has a molecular mass of 130 kDa and is immunoprecipitated using either mAb 3A11 or soluble CD6-Ig fusion protein. mAbs directed against individual CD6L were less potent than was soluble CD6-Ig fusion protein in reducing adhesion of T cells to adherent 3A11-positive epithelial cells in vitro, suggesting that these Abs recognize epitopes on the 3A11 Ag and CD166 that are distinct from CD6 binding sites. Finally, transfection of epithelial cells with CD166-specific small interfering RNAs significantly decreased CD166 expression without alteration in 3A11 Ag levels, and thus confirmed that these two CD6L are distinct. Taken together, our data identifies a novel 130-kDa CD6L that may mediate interactions of synovial and epithelial cells with T lymphocytes.
Human Ribonuclease A Superfamily Members, Eosinophil-Derived Neurotoxin and Pancreatic Ribonuclease, Induce Dendritic Cell Maturation and Activation
Authors: Yang De , Chen Qian , Rosenberg Helene F. , Rybak Susanna M. , Newton Dianne L. , Wang Zhao Yuan , Fu Qin , Tchernev Velizar T. , Wang Minjuan , Schweitzer Barry , Kingsmore Stephen F. , Patel Dhavalkumar D. , Oppenheim Joost J. , Howard O. M. Zack
Published: April 2014

A number of mammalian antimicrobial proteins produced by neutrophils and cells of epithelial origin have chemotactic and activating effects on host cells, including cells of the immune system. Eosinophil granules contain an antimicrobial protein known as eosinophil-derived neurotoxin (EDN), which belongs to the RNase A superfamily. EDN has antiviral and chemotactic activities in vitro. In this study, we show that EDN, and to a lesser extent human pancreatic RNase (hPR), another RNase A superfamily member, activates human dendritic cells (DCs), leading to the production of a variety of inflammatory cytokines, chemokines, growth factors, and soluble receptors. Human angiogenin, a RNase evolutionarily more distant to EDN and hPR, did not display such activating effects. Additionally, EDN and hPR also induced phenotypic and functional maturation DCs. These RNases were as efficacious as TNF-α, but induced a different set of cytokine mediators. Furthermore, EDN production by human macrophages could be induced by proinflammatory stimuli. The results reveal the DC-activating activity of EDN and hPR and suggest that they are likely participants of inflammatory and immune responses. A number of endogenous mediators in addition to EDN have been reported to have both chemotactic and activating effects on APCs, and can thus amplify innate and Ag-specific immune responses to danger signals. We therefore propose these mediators be considered as endogenous multifunctional immune alarmins.
Vesicle Size Influences the Trafficking, Processing, and Presentation of Antigens in Lipid Vesicles
Authors: Brewer James M. , Pollock Kevin G. J. , Tetley Laurence , Russell David G.
Published: April 2014

Although it is accepted that particulate Ags are more immunogenic than soluble Ags in vivo, it is unclear whether this effect can be explained solely through enhanced uptake by APCs. In this study we demonstrate that vesicle size modulated the efficiency of Ag presentation by murine macrophages and that this effect was accompanied by a profound change in trafficking of Ag. Ag prepared in large particles (560 nm) was delivered into early endosome-like, immature phagosomes, whereas smaller vesicles (155 nm) and soluble Ags localized rapidly to late endosomes/lysosomes. However, peptide/class II complexes could be detected in both compartments. Phagosomes formed on uptake of large vesicles recruit Ag-processing apparatus while retaining the characteristics of early endosomes. In contrast, smaller vesicles bypassed this compartment, appeared to go more rapidly to lysosomal compartments, and exhibited reduced Ag-presenting efficiency. We conclude that the ability of phagocytosed, particulate Ag to target early phagosomes results in more efficient Ag presentation.
IκB Kinase Complex α Kinase Activity Controls Chemokine and High Endothelial Venule Gene Expression in Lymph Nodes and Nasal-Associated Lymphoid Tissue
Authors: Drayton Danielle L. , Bonizzi Giuseppina , Ying Xiaoyan , Liao Shan , Karin Michael , Ruddle Nancy H.
Published: April 2014

The lymphotoxin (LT) β receptor plays a critical role in secondary lymphoid organogenesis and the classical and alternative NF-κB pathways have been implicated in this process. IKKα is a key molecule for the activation of the alternative NF-κB pathway. However, its precise role and target genes in secondary lymphoid organogenesis remain unknown, particularly with regard to high endothelial venules (HEV). In this study, we show that IKKαAA mutant mice, who lack inducible kinase activity, have hypocellular lymph nodes (LN) and nasal-associated lymphoid (NALT) tissue characterized by marked defects in microarchitecture and HEV. In addition, IKKαAA LNs showed reduced lymphoid chemokine CCL19, CCL21, and CXCL13 expression. IKKαAA LN- and NALT-HEV were abnormal in appearance with reduced expression of peripheral node addressin (PNAd) explained by a severe reduction in the HEV-associated proteins, glycosylation-dependent cell adhesion molecule 1 (GlyCAM-1), and high endothelial cell sulfotransferase, a PNAd-generating enzyme that is a target of LTαβ. In this study, analysis of LTβ−/− mice identifies GlyCAM-1 as another LTβ-dependent gene. In contrast, TNFRI−/− mice, which lose classical NF-κB pathway activity but retain alternative NF-κB pathway activity, showed relatively normal GlyCAM-1 and HEC-6ST expression in LN-HEV. In addition, in this communication, it is demonstrated that LTβR is prominently expressed on LN- and NALT-HEV. Thus, these data reveal a critical role for IKKα in LN and NALT development, identify GlyCAM-1 and high endothelial cell sulfotransferase as new IKKα-dependent target genes, and suggest that LTβR signaling on HEV can regulate HEV-specific gene expression.
PIASy-Deficient Mice Display Modest Defects in IFN and Wnt Signaling
Authors: Roth Wera , Sustmann Claudio , Kieslinger Matthias , Gilmozzi Andrea , Irmer Denis , Kremmer Elisabeth , Turck Chris , Grosschedl Rudolf
Published: April 2014

Protein inhibitors of activated STATs (PIAS) represent a small family of nuclear proteins that modulate the activity of many transcription factors and act as E3 ligases for covalent modification of proteins with the small ubiquitin-like modifier (SUMO). In particular, PIASy has been shown to inhibit the activation of gene expression by the IFN-responsive transcription factor STAT1 and the Wnt-responsive transcription factor LEF1. To assess the function of PIASy in vivo, we generated and analyzed mice carrying a targeted mutation of the Piasy gene. We find that homozygous mutant mice have no obvious morphological defects and have a normal distribution of lymphocyte populations. Molecular analysis of signaling in response to IFN-γ and Wnt agonists revealed a modest reduction in the activation of endogenous and transfected target genes. Two-dimensional analysis of total proteins and SUMO-modified proteins in transformed pre-B cells showed no significant differences between wild-type mice and homozygous mutant mice. Taken together, our data indicate that PIASy has a modest effect on cytokine and Wnt signaling, suggesting a redundancy with other members of the family of PIAS proteins.
The Bax N Terminus Is Required for Negative Regulation by the Mitogen-Activated Protein Kinase Kinase and Akt Signaling Pathways in T Cells
Authors: Parikh Neha , Sade Hadassah , Kurian Leo , Sarin Apurva
Published: April 2014

The Bcl-2 family proapoptotic protein, Bax, redistributes to the mitochondrion in response to varied stimuli, triggering loss of mitochondrial integrity and apoptosis. Suppression of MAPK kinase (MEK1) by the reagent UO126 in activated T cells maintained in the cytokine IL-2 disrupts cytoplasmic localization of Bax and cell survival. UO126 triggers mitochondrial translocation of ectopically expressed Bax-GFP, and both UO126 and dominant negative MEK-1 (DN-MEK1) trigger increased apoptosis in Bax-GFP-expressing T cell lines. Because inhibition of PI3K or its target Akt also triggers mitochondrial translocation of Bax in T cells and apoptosis in Bax-transfected cell lines, we generated Bax deletion mutants to identify the region(s) that confers sensitivity to regulation by MEK1 and Akt. A deletion mutant (Bax1–171) without the C terminus mitochondrial targeting sequence or an Akt target site (Ser184) localizes to the cytoplasm and triggers low level apoptosis that is enhanced by DN-Akt or DN-MEK1. A construct that lacks the first 29 aa (Bax-δ29) largely localizes to mitochondria, is highly apoptogenic, and is not inhibited by Akt or MEK1. Furthermore, Bax-δ29 overcomes IL-2-dependent survival in a T cell line, whereas Bax triggers comparatively low levels of apoptosis in these cells. Cytoplasmic localization and regulation by MEK1 and Akt are restored in a mutant deleted of the first 13 aa (Bax-δ13). Taken together, our results identify a region in the Bax N terminus that determines cellular localization regulated by MEK- and Akt-dependent signaling in T cells.
Identification and Partial Characterization of a Variant of Human CXCR3 Generated by Posttranscriptional Exon Skipping
Authors: Ehlert Jan Erik , Addison Christina A. , Burdick Marie D. , Kunkel Steven L. , Strieter Robert M.
Published: April 2014

Chemokines are recognized as functionally important in many pathological disorders, which has led to increased interest in mechanisms related to the regulation of chemokine receptor (CKR) expression. Known mechanisms for regulating CKR activity are changes in gene expression or posttranslational modifications. However, little is known about CKR with respect to a third regulatory mechanism, which is observed among other seven-transmembrane receptor subfamilies, the concept of differential splicing or processing of heteronuclear RNA. We now report on the discovery of a variant human CKR, CXCR3, resulting from alternative splicing via exon skipping. The observed RNA processing entails a drastically altered C-terminal protein sequence with a predicted four- or five-transmembrane domain structure, differing from all known functional CKR. However, our data indicate that that this splice variant, which we termed CXCR3-alt, despite its severe structural changes still localizes to the cell surface and mediates functional activity of CXCL11.
The Functional Interaction of the β2 Integrin Lymphocyte Function-Associated Antigen-1 with Junctional Adhesion Molecule-A Is Mediated by the I Domain
Authors: Fraemohs Line , Koenen Rory R. , Ostermann Georg , Heinemann Bo , Weber Christian
Published: April 2014

Binding of the β2 integrin LFA-1 (αLβ2) to junctional adhesion molecule-A (JAM-A) has been shown to enhance leukocyte adhesion and transendothelial migration. This is mediated by the membrane-proximal Ig-like domain 2 of JAM-A; however, the location of the JAM-A binding site in LFA-1 has not been identified. We have deleted the I domain in the αL subunit of LFA-1 and expressed this αL mutant in αl-deficient Jurkat J-β2.7 cells to demonstrate that the I domain of LFA-1 is crucial for their adhesion to immobilized JAM-A. This was substantiated by blocking the stimulated adhesion of wild-type Jurkat T cells or monocytic Mono Mac 6 cells to JAM-A using the I domain-directed mAb TS1/22 or the small molecule antagonist BIRT 377, which stabilizes the low-affinity conformation of the I domain. The immobilized LFA-1 I domain locked in the open high-affinity conformation was sufficient to support binding of transfected Chinese hamster ovary cells expressing JAM-A. Solid-phase binding assays confirmed a direct interaction of recombinant JAM-A with the immobilized locked-open I domain. These data provide the first evidence that the I domain of LFA-1 contains a functional binding site for JAM-A.
Differential Regulation of Primary and Secondary CD8+ T Cells in the Central Nervous System
Authors: Ramakrishna Chandran , Stohlman Stephen A. , Atkinson Roscoe A. , Hinton David R. , Bergmann Cornelia C.
Published: April 2014

T cell accumulation and effector function following CNS infection is limited by a paucity of Ag presentation and inhibitory factors characteristic of the CNS environment. Differential susceptibilities of primary and recall CD8+ T cell responses to the inhibitory CNS environment were monitored in naive and CD8+ T cell-immune mice challenged with a neurotropic coronavirus. Accelerated virus clearance and limited spread in immunized mice was associated with a rapid and increased CNS influx of virus-specific secondary CD8+ T cells. CNS-derived secondary CD8+ T cells exhibited increased cytolytic activity and IFN-γ expression per cell compared with primary CD8+ T cells. However, both Ag-specific primary and secondary CD8+ T cells demonstrated similar contraction rates. Thus, CNS persistence of increased numbers of secondary CD8+ T cells reflected differences in the initial pool size during peak inflammation rather than enhanced survival. Unlike primary CD8+ T cells, persisting secondary CD8+ T cells retained ex vivo cytolytic activity and expressed high levels of IFN-γ following Ag stimulation. However, both primary and secondary CD8+ T cells exhibited reduced capacity to produce TNF-α, differentiating them from effector memory T cells. Activation of primary and secondary CD8+ T cells in the same host using adoptive transfers confirmed similar survival, but enhanced and prolonged effector function of secondary CD8+ T cells in the CNS. These data suggest that an instructional program intrinsic to T cell differentiation, rather than Ag load or factors in the inflamed CNS, prominently regulate CD8+ T cell function.
Single-Epitope DNA Vaccination Prevents Exhaustion and Facilitates a Broad Antiviral CD8+ T Cell Response during Chronic Viral Infection
Authors: Bartholdy Christina , Stryhn Anette , Christensen Jan Pravsgaard , Thomsen Allan Randrup
Published: April 2014

Induction of a monospecific antiviral CD8+ T cell response may pose a risk to the host due to the narrow T cell response induced. At the individual level, this may result in selection of CD8+ T cell escape variants, particularly during chronic viral infection. Second, prior immunization toward a single dominant epitope may suppress the response to other viral epitopes, and this may lead to increased susceptibility to reinfection with escape variants circulating in the host population. To address these issues, we induced a memory response consisting solely of monospecific, CD8+ T cells by use of DNA vaccines encoding immunodominant epitopes of lymphocytic choriomeningitis virus (LCMV). We analyzed the spectrum of the CD8+ T cell response and the susceptibility to infection in H-2b and H-2d mice. Priming for a monospecific, CD8+ T cell response did not render mice susceptible to viral variants. Thus, vaccinated mice were protected against chronic infection with LCMV, and no evidence indicating biologically relevant viral escape was obtained. In parallel, a broad and sustained CD8+ T cell response was generated upon infection, and in H-2d mice epitope spreading was observed. Even after acute LCMV infection, DNA vaccination did not significantly impair naturally induced immunity. Thus, the response to the other immunogenic epitopes was not dramatically suppressed in DNA-immunized mice undergoing normal immunizing infection, and the majority of mice were protected against rechallenge with escape variants. These findings underscore that a monospecific vaccine may induce efficient protective immunity given the right set of circumstances.
Maximum Immunobioactivity of Murine Small Intestinal Intraepithelial Lymphocytes Resides in a Subpopulation of CD43+ T Cells
Authors: Wang Heuy-Ching , Montufar-Solis Dina , Teng Ba-Bie , Klein John R.
Published: April 2014

CD43 has been linked to many function-associated T cell activities. Using mAbs that recognize two different CD43 determinants, we show that, although mouse small intestinal intraepithelial lymphocytes (IELs) expressed the CD43 core molecule reactive with mAb R2/60, only about one-half of the total IELs—including some but not all of the TCRαβ and TCRγδ cells—expressed the CD43 S7− reactive determinant. CD43 S7+ IELs secreted more IL-2, IL-4, IL-10, IL-17, and IFN-γ following anti-CD3 stimulation, and were >4-fold more cytotoxic in fresh isolates and >16-fold more cytotoxic after anti-CD3 stimulation, than S7− IELs. S7+ but not S7− IELs from the ileum of IL-10−/− mice spontaneously produced IFN-γ. In vivo BrdU uptake by IELs in non-Ag-primed mice was greatest in the S7+ population, indicating that significantly more S7+ IELs than S7− IELs undergo cell expansion under normal homeostatic conditions. DNA microarray analyses showed that S7+ IELs expressed higher levels of genes associated with activated T cells, whereas S7− IELs expressed genes used in the regulation of NK cells. These findings define two functionally distinct populations of IELs based on CD43 expression independent of TCR class, and they identify a subset of IELs that may serve as a target to better control intestinal inflammation.
Cmv1-Independent Antiviral Role of NK Cells Revealed in Murine Cytomegalovirus-Infected New Zealand White Mice
Authors: Rodriguez Marisela , Sabastian Pearl , Clark Patricia , Brown Michael G.
Published: April 2014

Ly49H+ NK cells play a critical role in innate antiviral immune responses to murine CMV (MCMV). Ly49Hb6 recognition of MCMV-encoded m157 on infected cells activates natural killing required for host resistance. We show that mAb 3D10 (anti-Ly49H) recognizes comparable subsets of NK cells from New Zealand White (NZW), New Zealand Black (NZB), and C57BL/6 spleens. However, virus levels in the spleens of MCMV-infected NZW and NZB mice differed greatly. We found that MCMV replication in infected NZW spleens was limited through NK cells. Alternately, NZB mice were profoundly susceptible to MCMV infection. Although 3D10 mAb injections given before infection interfere with Cmv1-type resistance in C57BL/6 mice, similar mAb injections did not affect NZW resistance, likely because NZW NK cell receptors did not bind MCMV-encoded m157. Instead, anti-MCMV host defenses in hybrid NZ offspring were associated with multiple chromosome locations including several putative quantitative trait loci that did not overlap with H-2 or NK gene complex loci. This study revealed a novel pathway used by NK cells to defend against MCMV infection. Thus, the importance of Ly49H in MCMV infection may be shaped by other additional background genes.
Multiple Roles of CLAN (Caspase-Associated Recruitment Domain, Leucine-Rich Repeat, and NAIP CIIA HET-E, and TP1-Containing Protein) in the Mammalian Innate Immune Response
Authors: Damiano Jason S. , Newman Ruchi M. , Reed John C.
Published: April 2014

NAIP CIIA HET-E and TP1 (NACHT) family proteins are involved in sensing intracellular pathogens or pathogen-derived molecules, triggering host defense responses resulting in caspase-mediated processing of proinflammatory cytokines and NF-κB activation. Caspase-associated recruitment domain, leucine-rich repeat, and NACHT-containing protein (CLAN), also known as ICE protease-activating factor, belongs to a branch of the NACHT family that contains proteins carrying caspase-associated recruitment domains (CARDs) and leucine-rich repeats (LRRs). By using gene transfer and RNA-interference approaches, we demonstrate in this study that CLAN modulates endogenous caspase-1 activation and subsequent IL-1β secretion from human macrophages after exposure to LPS, peptidoglycan, and pathogenic bacteria. CLAN was also found to mediate a direct antibacterial effect within macrophages after Salmonella infection and to sensitize host cells to Salmonella-induced cell death through a caspase-1-independent mechanism. These results indicate that CLAN contributes to several biological processes central to host defense, suggesting a prominent role for this NACHT family member in innate immunity.
Ethanol Blocks Leukocyte Recruitment and Endothelial Cell Activation In Vivo and In Vitro
Authors: Saeed Rubina W. , Varma Santosh , Peng Tina , Tracey Kevin J. , Sherry Barbara , Metz Christine N.
Published: April 2014

Immune system impairment and increased susceptibility to infection among alcohol abusers is a significant but not well-understood problem. We hypothesized that acute ethanol administration would inhibit leukocyte recruitment and endothelial cell activation during inflammation and infection. Using LPS and carrageenan air pouch models in mice, we found that physiological concentrations of ethanol (1–5 g/kg) significantly blocked leukocyte recruitment (50–90%). Because endothelial cell activation and immune cell-endothelial cell interactions are critical regulators of leukocyte recruitment, we analyzed the effect of acute ethanol exposure on endothelial cell activation in vivo using the localized Shwartzman reaction model. In this model, ethanol markedly suppressed leukocyte accumulation and endothelial cell adhesion molecule expression in a dose-dependent manner. Finally, we examined the direct effects of ethanol on endothelial cell activation and leukocyte-endothelial cell interactions in vitro. Ethanol, at concentrations within the range found in human blood after acute exposure and below the levels that induce cytotoxicity (0.1–0.5%), did not induce endothelial cell activation, but significantly inhibited TNF-mediated endothelial cell activation, as measured by adhesion molecule (E-selectin, ICAM-1, VCAM-1) expression and chemokine (IL-8, MCP-1, RANTES) production and leukocyte adhesion in vitro. Studies exploring the potential mechanism by which ethanol suppresses endothelial cell activation revealed that ethanol blocked NF-κB nuclear entry in an IκBα-dependent manner. These findings support the hypothesis that acute ethanol overexposure may increase the risk of infection and inhibit the host inflammatory response, in part, by blocking endothelial cell activation and subsequent immune cell-endothelial cell interactions required for efficient immune cell recruitment.
Intranasal Exposure of Mice to House Dust Mite Elicits Allergic Airway Inflammation via a GM-CSF-Mediated Mechanism
Authors: Cates Elizabeth C. , Fattouh Ramzi , Wattie Jennifer , Inman Mark D. , Goncharova Susanna , Coyle Anthony J. , Gutierrez-Ramos José-Carlos , Jordana Manel
Published: April 2014

It is now well established that passive exposure to inhaled OVA leads to a state of immunological tolerance. Therefore, to elicit allergic sensitization, researchers have been compelled to devise alternative strategies, such as the systemic delivery of OVA in the context of powerful adjuvants, which are alien to the way humans are exposed and sensitized to allergens. The objectives of these studies were to investigate immune-inflammatory responses to intranasal delivery of a purified house dust mite (HDM) extract and to evaluate the role of GM-CSF in this process. HDM was delivered to BALB/c mice daily for 10 days. After the last exposure, mice were killed, bronchoalveolar lavage was performed, and samples were obtained. Expression/production of Th2-associated molecules in the lymph nodes, lung, and spleen were evaluated by real-time quantitative PCR and ELISA, respectively. Using this exposure protocol, exposure to HDM alone generated Th2 sensitization based on the expression/production of Th2 effector molecules and airway eosinophilic inflammation. Flow cytometric analysis demonstrated expansion and activation of APCs in the lung and an influx of activated Th2 effector cells. Moreover, this inflammation was accompanied by airways hyper-responsiveness and a robust memory-driven immune response. Finally, administration of anti-GM-CSF-neutralizing Abs markedly reduced immune-inflammatory responses in both lung and spleen. Thus, intranasal delivery of HDM results in Th2 sensitization and airway eosinophilic inflammation that appear to be mediated, at least in part, by endogenous GM-CSF production.
Platelet Endothelial Cell Adhesion Molecule Deficiency or Blockade Significantly Reduces Leukocyte Emigration in a Majority of Mouse Strains
Authors: Schenkel Alan R. , Chew Tina W. , Muller William A.
Published: April 2014

PECAM is a molecule used specifically during the diapedesis step when neutrophils and monocytes leave the blood compartment. Anti-PECAM reagents, such as Abs and soluble fusion proteins, block diapedesis both in vivo and in vitro. However, the PECAM knockout mouse in C57BL/6 strain has no serious defects in most models of inflammation. We show in this study that the same PECAM knockout backcrossed into the FVB/n strain clearly has reduced leukocyte emigration in two models of inflammation. Furthermore, we show that anti-PECAM reagents can block leukocyte emigration in several other wild-type strains of mice like FVB/n, SJL, and the outbred strain Swiss Webster. This clearly shows that the C57BL/6 strain is uniquely able to compensate for the loss of PECAM function. Murine models of inflammatory disease that have been studied using C57BL/6 mice should be re-evaluated using FVB/n or other mouse strains to determine whether PECAM plays a role in those models.
IL-5 and Granulocyte-Macrophage Colony-Stimulating Factor Activate STAT3 and STAT5 and Promote Pim-1 and Cyclin D3 Protein Expression in Human Eosinophils
Authors: Stout Barbara A. , Bates Mary Ellen , Liu Lin Ying , Farrington Natasha N. , Bertics Paul J.
Published: April 2014

Allergic inflammation is characterized by elevated eosinophil numbers and by the increased production of the cytokines IL-5 and GM-CSF, which control several eosinophil functions, including the suppression of apoptosis. The JAK/STAT pathway is important for several functions in hemopoietic cells, including the suppression of apoptosis. We report in this study that STAT3, STAT5a, and STAT5b are expressed in human eosinophils and that their signaling pathways are active following IL-5 or GM-CSF treatment. However, in airway eosinophils, the phosphorylation of STAT5 by IL-5 is reduced, an event that may be related to the reduced expression of the IL-5Rα on airway eosinophils. Furthermore, IL-5 and GM-CSF induced the protein expression of cyclin D3 and the kinase Pim-1, both of which are regulated by STAT-dependent processes in some cell systems. Pim-1 is more abundantly expressed in airway eosinophils than in blood eosinophils. Because Pim-1 reportedly has a role in the modulation of apoptosis, these results suggest that Pim-1 action is linked to the suppression of eosinophil apoptosis by these cytokines. Although cyclin D3 is known to be critical for cell cycle progression, eosinophils are terminally differentiated cells that do not proceed through the cell cycle. Thus, this apparent cytokine regulation of cyclin D3 suggests that there is an alternative role(s) for cyclin D3 in eosinophil biology.
CD56bright NK Cells Are Enriched at Inflammatory Sites and Can Engage with Monocytes in a Reciprocal Program of Activation
Authors: Dalbeth Nicola , Gundle Roger , Davies Robert J. O. , Lee Y. C. Gary , McMichael Andrew J. , Callan Margaret F. C.
Published: April 2014

Human NK cells may be divided into a CD56dim subset and a CD56bright subset. In peripheral blood, CD56dim NK cells dominate, whereas in lymph nodes, CD56bright NK cells are more common. In this study we show that CD56bright NK cells accumulate within inflammatory lesions in a wide variety of clinical diseases affecting several different anatomical sites. We demonstrate that when activated by the monokines IL-12, IL-15, and IL-18, these NK cells promote TNF-α production by CD14+ monocytes in a manner that is dependent on cell:cell contact. Conversely, CD14+ monocytes synergize with monokines to promote IFN-γ production by these NK cells. Again, this interaction is dependent on cell:cell contact. The experiments show that CD56bright NK cells accumulate in inflammatory lesions and, in the appropriate cytokine environment, can engage with CD14+ monocytes in a reciprocal activatory fashion, thereby amplifying the inflammatory response. Such a positive feedback loop is likely to be important in the pathogenesis of chronic inflammatory conditions such as rheumatoid arthritis.
Identification of Selective Basophil Chemoattractants in Human Nasal Polyps as Insulin-Like Growth Factor-1 and Insulin-Like Growth Factor-2
Authors: Hartnell Adele , Heinemann Akos , Conroy Dolores M. , Wait Robin , Sturm Gunter J. , Caversaccio Marco , Jose Peter J. , Williams Timothy J.
Published: April 2014

In a search for novel leukocyte chemoattractants at sites of allergic inflammation, we found basophil-selective chemoattractant activity in extracts of human nasal polyps. The extracts were fractionated by reverse phase HPLC, and the resulting fractions were tested for leukocyte-stimulating activity using sensitive shape change assays. The basophil-selective activity detected was not depleted by a poxvirus CC-chemokine-binding protein affinity column. This activity was further purified by HPLC, and proteins in the bioactive fractions were analyzed by tandem electrospray mass spectrometry. Insulin-like growth factor-2 (IGF-2) was identified in these HPLC fractions, and the basophil-stimulating activity was inhibited by an anti-IGF-2-neutralizing Ab. Recombinant IGF-2 induced a substantial shape change response in basophils, but not eosinophils, neutrophils, or monocytes. IGF-2 stimulated chemokinesis of basophils, but not eosinophils or neutrophils, and synergized with eotaxin-1/CCL11 in basophil chemotaxis. IGF-2 also caused up-regulation of basophil CD11b expression and inhibited apoptosis, but did not stimulate degranulation or Ca2+ flux. Recombinant IGF-1 exhibited similar basophil-selective effects as IGF-2, and both growth factors were detected in nasal polyp extracts by ELISA. This is the first demonstration of chemokinetic factors that increase the motility of basophils, but do not act on other granulocytes or monocytes. IGF-1 and IGF-2 could play a role in the selective recruitment of basophils in vivo.
Decreased Expression of the Ets Family Transcription Factor Fli-1 Markedly Prolongs Survival and Significantly Reduces Renal Disease in MRL/lpr Mice
Authors: Zhang Xian K. , Gallant Sarah , Molano Ivan , Moussa Omar M. , Ruiz Phillip , Spyropoulos Demetri D. , Watson Dennis K. , Gilkeson Gary
Published: April 2014

Increased Fli-1 mRNA is present in PBLs from systemic lupus erythematosus patients, and transgenic overexpression of Fli-1 in normal mice leads to a lupus-like disease. We report in this study that MRL/lpr mice, an animal model of systemic lupus erythematosus, have increased splenic expression of Fli-1 protein compared with BALB/c mice. Using mice with targeted gene disruption, we examined the effect of reduced Fli-1 expression on disease development in MRL/lpr mice. Complete knockout of Fli-1 is lethal in utero. Fli-1 protein expression in heterozygous MRL/lpr (Fli-1+/−) mice was reduced by 50% compared with wild-type MRL/lpr (Fli-1+/+) mice. Fli-1+/− MRL/lpr mice had significantly decreased serum levels of total IgG and anti-dsDNA Abs as disease progressed. Fli-1+/− MRL/lpr mice had significantly increased splenic CD8+ and naive T cells compared with Fli-1+/+ MRL/lpr mice. Both in vivo and in vitro production of MCP-1 were significantly decreased in Fli-1+/− MRL/lpr mice. The Fli-1+/− mice had markedly decreased proteinuria and significantly lower pathologic renal scores. At 48 wk of age, survival was significantly increased in the Fli-1+/− MRL/lpr mice, as 100% of Fli-1+/− MRL/lpr mice were alive, in contrast to only 27% of Fli-1+/+ mice. These findings indicate that Fli-1 expression is important in lupus-like disease development, and that modulation of Fli-1 expression profoundly decreases renal disease and improves survival in MRL/lpr mice.
CD30/CD30 Ligand (CD153) Interaction Regulates CD4+ T Cell-Mediated Graft-versus-Host Disease
Authors: Blazar Bruce R. , Levy Robert B. , Mak Tak W. , Panoskaltsis-Mortari Angela , Muta Hiromi , Jones Monica , Roskos Melinda , Serody Jonathan S. , Yagita Hideo , Podack Eckhard R. , Taylor Patricia A.
Published: April 2014

CD30, a TNFR family member, is expressed on activated CD4+ and CD8+ T cells and B cells and is a marker of Hodgkin’s lymphoma; its ligand, CD30L (CD153) is expressed by activated CD4+ and CD8+ T cells, B cells, and macrophages. Signaling via CD30 can lead to proliferation or cell death. CD30-deficient (−/−) mice have impaired thymic negative selection and increased autoreactivity. Although human alloreactive T cells preferentially reside within the CD30+ T cell subset, implicating CD30 as a regulator of T cell immune responses, the role of CD30/CD153 in regulating graft-vs-host disease (GVHD) has not been reported. We used a neutralizing anti-CD153 mAb, CD30−/− donor mice, and generated CD153−/− recipient mice to analyze the effect of CD30/CD153 interaction on GVHD induction. Our data indicate that the CD30/CD153 pathway is a potent regulator of CD4+, but not CD8+, T cell-mediated GVHD. Although blocking CD30/CD153 interactions in vivo did not affect alloreactive CD4+ T cell proliferation or apoptosis, a substantial reduction in donor CD4+ T cell migration into the gastrointestinal tract was readily observed with lesser effects in other GVHD target organs. Blockade of the CD30/CD153 pathway represents a new approach for preventing CD4+ T cell-mediated GVHD.
CD4+CD25bright T Cells in Human Intestinal Lamina Propria as Regulatory Cells
Authors: Makita Shin , Kanai Takanori , Oshima Shigeru , Uraushihara Koji , Totsuka Teruji , Sawada Taisuke , Nakamura Tetsuya , Koganei Kazutaka , Fukushima Tsuneo , Watanabe Mamoru
Published: April 2014

It is well known that immune responses in the intestine remain in a state of controlled inflammation, suggesting that not only active suppression by regulatory T cells plays an important role in the normal intestinal homeostasis, but also its dysregulation leads to the development of inflammatory bowel disease. In this study, we demonstrate that the CD4+CD25bright T cells reside in the human intestinal lamina propria (LP) and functionally retain regulatory activities. All human LP CD4+ T cells regardless of CD25 expression constitutively expressed CTLA-4, glucocorticoid-induced TNFR family-related protein, and Foxp3 and proliferate poorly. Although LP CD4+CD25− T cells showed an activated and anergic/memory phenotype, they did not retain regulatory activity. In LP CD4+CD25+ T cells, however, cells expressing CD25 at high levels (CD4+CD25bright) suppressed the proliferation and various cytokine productions of CD4+CD25− T cells. LP CD4+CD25bright T cells by themselves produced fewer amounts of IL-2, IFN-γ, and IL-10. Interestingly, LP CD4+CD25bright T cells with regulatory T activity were significantly increased in patients with active inflammatory bowel disease. These results suggest that CD4+CD25bright T cells found in the normal and inflamed intestinal mucosa selectively inhibit the host immune response and therefore may contribute to the intestinal immune homeostasis.
Proliferation and Differentiation of CD8+ T Cells in the Absence of IL-2/15 Receptor β-Chain Expression or STAT5 Activation
Authors: Teague Ryan M. , Tempero Richard M. , Thomas Sunil , Murali-Krishna Kaja , Nelson Brad H.
Published: April 2014

Major gains in the efficacy of T cell-based therapies for cancer and infectious diseases could be realized through improved understanding of the signals that control expansion and differentiation of CD8+ cytolytic T cells. IL-2, IL-15, and the downstream transcription factor STAT5 have all been implicated as important regulators of these processes, yet there are conflicting data regarding their contribution to in vivo T cell responses. We used a murine adoptive T cell transfer model to examine the contribution of IL-2 and IL-15 signaling to the proliferation and differentiation of naive, CD8+ T cells bearing an OVA-specific TCR transgene (OT-I). OT-I T cells failed to express the high affinity IL-2R (CD25) while proliferating in vivo, irrespective of the mode of Ag delivery. Moreover, OT-I T cells rendered genetically deficient in the shared IL-2/IL-15Rβ subunit (IL-2Rβ) demonstrated normal Ag-induced proliferation and cytolytic activity in vivo. Accordingly, activation of STAT5 was not detected in proliferating IL-2Rβ-deficient OT-I T cells, thus implicating a STAT5-independent cytokine or costimulatory pathway in this process. Even though IL-2 and IL-15 were dispensable for CD8+ T cell proliferation, systemic infusion of IL-2 nevertheless promoted the expansion of OT-I T cells in vivo. Thus, IL-2 and IL-15 signals are not essential for CD8+ T cell proliferation or differentiation, but IL-2 can promote supraphysiological expansion when supplied exogenously. These findings challenge current models that place CD8+ T cell proliferation under the control of STAT5-dependent cytokines and suggest new approaches to the therapeutic manipulation of T cell numbers in vivo.
Functional Analysis of −571 IL-10 Promoter Polymorphism Reveals a Repressor Element Controlled by Sp1
Authors: Steinke John W. , Barekzi Elizabeth , Hagman James , Borish Larry
Published: April 2014

Transcriptional dysregulation of the IL-10 gene may contribute to the development and severity of autoimmune, infectious, neoplastic, and allergic diseases. A C to A base substitution has been identified at −571 bp in the IL-10 promoter and has been linked to immune diseases. The role of this polymorphism in IL-10 promoter function was assessed using luciferase reporter constructs. The presence of an A at −571 (A allele) increases promoter activity compared with that of a promoter with a C at this position (C allele). Binding of nuclear extract proteins from IL-10-producing human cell lines to DNA sequences including this base exchange and flanking sequences was demonstrated using EMSAs. Specific binding of the transcription factors Sp1 and Sp3 was demonstrated to a region immediately upstream of the polymorphism. No differences in the binding affinity of recombinant Sp1 were observed between the two forms of the promoter. Reconstitution of Sp1 expression decreased IL-10 promoter function in an Sp1-deficient cell line, demonstrating that this element functions as a repressor. The C to A base exchange relieves the repression mediated by Sp1. Individuals carrying the A allele of the IL-10 promoter may display increased synthesis of IL-10, resulting in suppressed immune responses and a modulation of their susceptibility to autoimmune, infectious, neoplastic, or atopic disease.
The Chemoattractants, IL-8 and Formyl-Methionyl-Leucyl-Phenylalanine, Regulate Granulocyte Colony-Stimulating Factor Signaling by Inducing Suppressor of Cytokine Signaling-1 Expression
Authors: Stevenson Nigel J. , Haan Serge , McClurg Angela E. , McGrattan Michael J. , Armstrong Marilyn A. , Heinrich Peter C. , Johnston James A.
Published: April 2014

Suppressors of cytokine signaling (SOCS) are encoded by immediate early genes known to inhibit cytokine responses in a classical feedback loop. SOCS gene expression has been shown to be induced by many cytokines, growth factors, and innate immune stimuli, such as LPS. In this paper, we report that the chemoattractants, IL-8 and fMLP, up-regulate SOCS1 mRNA in human myeloid cells, primary human neutrophils, PBMCs, and dendritic cells. fMLP rapidly up-regulates SOCS1, whereas the induction of SOCS1 upon IL-8 treatment is delayed. IL-8 and fMLP did not signal via Jak/STATs in primary human macrophages, thus implicating the induction of SOCS by other intracellular pathways. As chemoattractant-induced SOCS1 expression in neutrophils may play an important role in regulating the subsequent response to growth promoting cytokines like G-CSF, we investigated the effect of chemoattractant-induced SOCS1 on cytokine signal transduction. We show that pretreatment of primary human neutrophils with fMLP or IL-8 blocks G-CSF-mediated STAT3 activation. This study provides evidence for cross-talk between chemoattractant and cytokine signal transduction pathways involving SOCS proteins, suggesting that these chemotactic factors may desensitize neutrophils to G-CSF via rapid induction of SOCS1 expression.
Rates of Recombination and Chain Pair Biases Greatly Influence the Primary γδ TCR Repertoire in the Thymus of Adult Mice
Authors: Pereira Pablo , Boucontet Laurent
Published: April 2014

Analyses of the rearrangement status of the TCRγ and TCRδ chain loci in progenies of individual γδ thymocytes showed a hierarchy of the different Vγ and Vδ gene segments to participate in a recombination reaction. Moreover, individual TCRγ chains only pair efficiently with a variable number of TCRδ chains. Interestingly, these two parameters are inversely correlated such that the TCRγ and TCRδ chains that rearrange more often show a higher level of restriction in their pairing capabilities. Our data suggest that these mechanisms, together with a natural variation affecting the expected frequencies at which rearrangement of different Vγ gene segments give raise to functional TCRγ chains, have coevolved to maximize the diversity of the γδ TCR repertoire minimizing the risk that a γδ T cell will express more than one TCR specificity at the cell surface, despite the fact that multiple TCRγ rearrangements take place in the same progenitor cell.
Signaling of Apoptosis through TLRs Critically Involves Toll/IL-1 Receptor Domain-Containing Adapter Inducing IFN-β, but Not MyD88, in Bacteria-Infected Murine Macrophages
Authors: Ruckdeschel Klaus , Pfaffinger Gudrun , Haase Rudolf , Sing Andreas , Weighardt Heike , Häcker Georg , Holzmann Bernhard , Heesemann Jürgen
Published: April 2014

TLRs are important sensors of the innate immune system that serve to identify conserved microbial components to mount a protective immune response. They furthermore control the survival of the challenged cell by governing the induction of pro- and antiapoptotic signaling pathways. Pathogenic Yersinia spp. uncouple the balance of life and death signals in infected macrophages, which compels the macrophage to undergo apoptosis. The initiation of apoptosis by Yersinia infection specifically involves TLR4 signaling, although Yersinia can activate TLR2 and TLR4. In this study we characterized the roles of downstream TLR adapter proteins in the induction of TLR-responsive apoptosis. Experiments using murine macrophages defective for MyD88 or Toll/IL-1R domain-containing adapter inducing IFN-β (TRIF) revealed that deficiency of TRIF, but not of MyD88, provides protection against Yersinia-mediated cell death. Similarly, apoptosis provoked by treatment of macrophages with the TLR4 agonist LPS in the presence of a proteasome inhibitor was inhibited in TRIF-defective, but not in MyD88-negative, cells. The transfection of macrophages with TRIF furthermore potently promoted macrophage apoptosis, a process that involved activation of a Fas-associated death domain- and caspase-8-dependent apoptotic pathway. These data indicate a crucial function of TRIF as proapoptotic signal transducer in bacteria-infected murine macrophages, an activity that is not prominent for MyD88. The ability to elicit TRIF-dependent apoptosis was not restricted to TLR4 activation, but was also demonstrated for TLR3 agonists. Together, these results argue for a specific proapoptotic activity of TRIF as part of the host innate immune response to bacterial or viral infection.