bluuebunny/crossref_metadata_2025_split huggingface dataset:
Allelic Exclusion of the TCR α-Chain Is an Active Process Requiring TCR-Mediated Signaling and c-Cbl
Authors: Niederberger Nathalie , Holmberg Kaisa , Alam S. Munir , Sakati Wayne , Naramura Mayumi , Gu Hua , Gascoigne Nicholas R. J. 
Published: April 2014

AbstractPhenotypic allelic exclusion at the TCRα locus is developmentally regulated in thymocytes. Many immature thymocytes express two cell surface α-chain species. Following positive selection, the vast majority of mature thymocytes and peripheral T cells display a single cell surface α-chain. A posttranslational mechanism occurring at the same time as positive selection and TCR up-regulation leads to this phenotypic allelic exclusion. Different models have been proposed to explain the posttranslational regulation of the α-chain allelic exclusion. In this study, we report that allelic exclusion is not regulated by competition between distinct α-chains for a single β-chain, as proposed by the dueling α-chain model, nor by limiting CD3 ζ-chain in mature TCRhigh thymocytes. Our data instead favor the selective retention model where the positive selection signal through the TCR leads to phenotypic allelic exclusion by specifically maintaining cell surface expression of the selected α-chain while the nonselected α-chain is internalized. The use of inhibitors specific for Lck and/or other Src kinases indicates a role for these protein tyrosine kinases in the signaling events leading to the down-regulation of the nonselectable α-chain. Loss of the ubiquitin ligase/TCR signaling adapter molecule c-Cbl, which is important in TCR down-modulation and is a negative regulator of T cell signaling, leads to increased dual α-chain expression on the cell surface of double-positive thymocytes. Thus, not only is there an important role for TCR signaling in causing α-chain allelic exclusion, but differential ubiquitination by c-Cbl may be an important factor in causing only the nonselected α-chain to be down-modulated.
B1 Cells Contribute to Serum IgM, But Not to Intestinal IgA, Production in Gnotobiotic Ig Allotype Chimeric Mice
Authors: Thurnheer M. Christine , Zuercher Adrian W. , Cebra John J. , Bos Nicolaas A. 
Published: April 2014

Abstract
B1 cells are a significant source of natural serum IgM, thereby serving as a first line of defense against systemic bacterial and viral infections. They can migrate to the intestinal lamina propria and differentiate into IgA-producing plasma cells and thus might play a similar role in mucosal immunity. To investigate the contribution of B1 cells to the intestinal IgA response induced by the commensal flora in immunocompetent animals, we generated gnotobiotic and conventionally reared Ig allotype chimeric mice. In this system B1- and B2-derived Abs can be distinguished based on different allotypes. FACS analysis of peritoneal cavity cells and analysis of B1- and B2-derived serum IgM indicated stable B1/B2 chimerism and the establishment of a functional B1 population. Monoassociation with either Morganella morganii, Bacteroides distasonis, or segmented filamentous bacteria induced germinal center reactions in Peyer’s patches and led to the production of intestinal IgA, partially reactive with bacterial Ag. A considerable amount of serum IgM was B1 cell derived in both monoassociated and conventionally reared mice. However, most of the total as well as bacteria-specific intestinal IgA was produced by B2 cells. These data suggest that intestinal IgA production induced by commensal bacteria is mainly performed by B2, not B1, cells.
TGF-β1 Suppresses Myeloid Fcγ Receptor Function by Regulating the Expression and Function of the Common γ-Subunit
Authors: Tridandapani Susheela , Wardrop Richard , Baran Christopher P. , Wang Yijie , Opalek Judy M. , Caligiuri Michael A. , Marsh Clay B. 
Published: April 2014

AbstractWe have previously reported that FcγR-mediated function in myeloid cells is a tightly regulated event that is influenced by the cytokines present in the milieu. TGF-β1 is an immunosuppressive cytokine with pleiotropic effects on immune responses; however, the molecular mechanism by which TGF-β suppresses immune responses is poorly understood. In this study, we have analyzed the effect of TGF-β on FcγR-mediated activation of myeloid cells. We report that TGF-β1-treated THP-1 human myeloid cells displayed reduced ability to phagocytose IgG-coated particles. Because FcγR expression is modulated by cytokines, we analyzed expression levels of FcγRI, FcγRIIa, FcγRIIb, and FcγRIIIa in cells cultured with or without TGF-β1 and found while total protein levels of the FcγR were not reduced, surface expression of FcγRI and FcγRIII was lower in cells cultured with TGF-β1. Concomitantly, there was a dose-dependent reduction in the expression of the FcγR-associated γ-subunit. This suppressive effect of TGF-β was likewise observed in bone marrow-derived murine myeloid cells and human monocytes. Importantly, TGF-β1 also significantly reduced the production of monocyte chemoattractant protein-1 induced by immobilized IgG, which would further reduce monocyte recruitment to the site of inflammation. In contrast, human alveolar macrophages were refractory to this effect, expressing low levels of TGF-β type II receptors compared with peripheral blood monocytes from the same donor. These data provide insight into the regulation of immune responses by TGF-β1 and demonstrate the selectivity of these effects.
The Cyclopentenone-Type Prostaglandin 15-Deoxy-Δ12,14-Prostaglandin J2 Inhibits CD95 Ligand Gene Expression in T Lymphocytes: Interference with Promoter Activation Via Peroxisome Proliferator-Activated Receptor-γ-Independent Mechanisms
Authors: Cippitelli Marco , Fionda Cinzia , Di Bona Danilo , Lupo Aldo , Piccoli Mario , Frati Luigi , Santoni Angela 
Published: April 2014

Abstract
15-Deoxy-Δ12,14-PGJ2 (15d-PGJ2) is a cyclopentenone-type PG endowed with anti-inflammatory properties and produced by different cells, including those of the immune system. 15d-PGJ2 is a natural ligand of the peroxisome proliferator-activated receptor (PPAR)-γ nuclear receptor, but relevant PPARγ-independent actions mediated by this prostanoid have been described. Fas (APO-1/CD95) and its ligand (Fas-L) are cell surface proteins whose interaction activates apoptosis of Fas-expressing targets. In T cells, the Fas-Fas-L system regulates activation-induced cell death and has been implicated in diseases in which lymphocyte homeostasis is compromised. Moreover, several studies have described the pathogenic functions of Fas and Fas-L in vivo, particularly in the induction-progression of organ-specific autoimmune diseases. In this study we describe the effect of 15d-PGJ2 on the activation of the fas-L gene in T lymphocytes. We show that 15d-PGJ2 inhibits fas-L mRNA expression, activation-induced cell death, and fas-L promoter activity by mechanisms independent of PPARγ and mediated by its chemically reactive cyclopentenone moiety. Our data indicate that 15d-PGJ2 may repress fas-L activation by interfering with the expression and/or transcriptional activity of different transcription factors (early growth response types 3 and 1, NF-κB, AP-1, c-Myc, Nur77) whose altered balancing and transactivation may contribute for overall repression of this gene. In addition, the activation/expression of the heat shock response genes HSF-1 and HSP70 is not directly involved in the repression, and the electrophilic molecule cyclopentenone (2-cyclopenten-1-one) may reproduce the effects mediated by 15d-PGJ2. These results suggest that modulation of Fas-L by 15d-PGJ2 in T cells may represent an additional tool to consider for treatment of specific autoimmune and inflammatory disorders.
Enforcedbcl-xLGene Expression Restored Splenic B Lymphocyte Development in BAFF-R Mutant Mice
Authors: Amanna Ian J. , Dingwall Jennifer P. , Hayes Colleen E. 
Published: April 2014

AbstractThe TNFR family member BAFF-R facilitates peripheral B cell development, although it is unclear whether it promotes survival of B cells, or also initiates a differentiation program. We show that disruption of the BAFF-R encoding gene Tnfrsf13c in strain A/WySnJ mice causes a progressive decline in peripheral B cell numbers, beginning at the transitional 1 developmental stage and continuing through the mature peripheral B cell stage. Bcl-xL overexpression in A/WySnJ B cells decreased the turnover of transitional B cells, as determined by 5-bromo-2′-deoxyuridine labeling, and restored follicular B cell development. We conclude that the mutant A/WySnJ allele of Tnfrsf13c can be complemented through the survival signal provided by Bcl-xL.
Influenza A Virus Infection Inhibits the Efficient Recruitment of Th2 Cells into the Airways and the Development of Airway Eosinophilia
Authors: Wohlleben Gisela , Müller Justus , Tatsch Ursula , Hambrecht Christine , Herz Udo , Renz Harald , Schmitt Edgar , Moll Heidrun , Erb Klaus J. 
Published: April 2014

AbstractMost infections with respiratory viruses induce Th1 responses characterized by the generation of Th1 and CD8+ T cells secreting IFN-γ, which in turn have been shown to inhibit the development of Th2 cells. Therefore, it could be expected that respiratory viral infections mediate protection against asthma. However, the opposite seems to be true, because viral infections are often associated with the exacerbation of asthma. For this reason, we investigated what effect an influenza A (flu) virus infection has on the development of asthma. We found that flu infection 1, 3, 6, or 9 wk before allergen airway challenge resulted in a strong suppression of allergen-induced airway eosinophilia. This effect was associated with strongly reduced numbers of Th2 cells in the airways and was not observed in IFN-γ- or IL-12 p35-deficient mice. Mice infected with flu virus and immunized with OVA showed decreased IL-5 and increased IFN-γ, eotaxin/CC chemokine ligand (CCL)11, RANTES/CCL5, and monocyte chemoattractant protein-1/CCL2 levels in the bronchoalveolar lavage fluid, and increased airway hyperreactivity compared with OVA-immunized mice. These results suggest that the flu virus infection reduced airway eosinophilia by inducing Th1 responses, which lead to the inefficient recruitment of Th2 cells into the airways. However, OVA-specific IgE and IgG1 serum levels, blood eosinophilia, and goblet cell metaplasia in the lung were not reduced by the flu infection. Flu virus infection also directly induced AHR and goblet cell metaplasia. Taken together, our results show that flu virus infections can induce, exacerbate, and suppress features of asthmatic disease in mice.
TGF-β1 Regulates Lymphocyte Homeostasis by Preventing Activation and Subsequent Apoptosis of Peripheral Lymphocytes
Authors: Bommireddy Ramireddy , Saxena Vijay , Ormsby Ilona , Yin Moying , Boivin Gregory P. , Babcock George F. , Singh Ram R. , Doetschman Thomas 
Published: April 2014

AbstractTGF-β1 plays an important role in the maintenance of immune homeostasis and self-tolerance. To determine the mechanism by which TGF-β1 prevents autoimmunity we have analyzed T cell activation in splenic lymphocytes from TGF-β1-deficient mice. Here we demonstrate that unlike wild-type splenic lymphocytes, those from Tgfb1−/− mice are hyporesponsive to receptor-mediated mitogenic stimulation, as evidenced by diminished proliferation and reduced IL-2 production. However, they have elevated levels of IFN-γ and eventually undergo apoptosis. Receptor-independent stimulation of Tgfb1−/− T cells by PMA plus ionomycin induces IL-2 production and mitogenic response, and it rescues them from anergy. Tgfb1−/− T cells display decreased CD3 expression; increased expression of the activation markers LFA-1, CD69, and CD122; and increased cell size, all of which indicate prior activation. Consistently, mutant CD4+ T cells have elevated intracellular Ca2+ levels. However, upon subsequent stimulation in vitro, increases in Ca2+ levels are less than those in wild-type cells. This is also consistent with the anergic phenotype. Together, these results demonstrate that the ex vivo proliferative hyporesponsiveness of Tgfb1−/− splenic lymphocytes is due to prior in vivo activation of T cells resulting from deregulated intracellular Ca2+ levels.
CD5 Inhibits Signaling at the Immunological Synapse Without Impairing Its Formation
Authors: Brossard Cédric , Semichon Monique , Trautmann Alain , Bismuth Georges 
Published: April 2014

AbstractPhysiologically, Ag detection by T cells occurs at the immunological synapse (IS) formed at the interface with an APC. CD5 is considered as an inhibitory molecule for Ag receptor-mediated signals in T cells. However, the influence of CD5 at the IS on synapse formation and functioning has not yet been reported. We demonstrate here that CD5 is recruited and tightly colocalized with CD3 in different human and murine IS. Following transfection in a CD5-negative T cell line of CD5 fused to the green fluorescent protein, we show that CD5 recruitment includes a fast Ag-independent and a slower Ag-dependent component. In video-imaging recordings of doubly transfected cells, the movements of CD3 and CD5 show similar kinetics, and the amount of CD3 recruited to the synapse is unaffected by CD5 expression. Moreover, APC-T cell adhesion is unchanged in CD5-expressing cells. Despite this, the extent of tyrosine phosphorylation at the synapse and the amplitude of calcium responses induced by Ag recognition are both decreased by CD5. These inhibitions increase with CD5 membrane levels. They also requires the pseudo-immunoreceptor tyrosine-based activation motif expressed in the cytoplasmic domain of the molecule. Thus, CD5 is rapidly recruited at the IS and lowers the T cell response elicited by Ag presentation by targeting downstream signaling events without affecting IS formation.
IKKβ Is Required for Peripheral B Cell Survival and Proliferation
Authors: Li Zhi-Wei , Omori Sidne A. , Labuda Tord , Karin Michael , Rickert Robert C. 
Published: April 2014

Abstract
NF-κB activity in mammalian cells is regulated through the IκB kinase (IKK) complex, consisting of two catalytic subunits (IKKα and IKKβ) and a regulatory subunit (IKKγ). Targeted deletion of Ikkβ results in early embryonic lethality, thus complicating the examination of IKKβ function in adult tissues. Here we describe the role of IKKβ in B lymphocytes made possible by generation of a mouse strain that expresses a conditional Ikkβ allele. We find that the loss of IKKβ results in a dramatic reduction in all peripheral B cell subsets due to associated defects in cell survival. IKKβ-deficient B cells are also impaired in mitogenic responses to LPS, anti-CD40, and anti-IgM, indicating a general defect in the ability to activate the canonical NF-κB signaling pathway. These findings are consistent with a failure to mount effective Ab responses to T cell-dependent and independent Ags. Thus, IKKβ provides a requisite role in B cell activation and maintenance and thus is a key determinant of humoral immunity.
Naive T Cell Recruitment to Nonlymphoid Tissues: A Role for Endothelium-Expressed CC Chemokine Ligand 21 in Autoimmune Disease and Lymphoid Neogenesis
Authors: Weninger Wolfgang , Carlsen Hege S. , Goodarzi Mahmoud , Moazed Farzad , Crowley Maura A. , Baekkevold Espen S. , Cavanagh Lois L. , von Andrian Ulrich H. 
Published: April 2014

AbstractNaive T cells are usually excluded from nonlymphoid tissues. Only when such tertiary tissues are subjected to chronic inflammation, such as in some (but not all) autoimmune diseases, are naive T cells recruited to these sites. We show that the CCR7 ligand CC chemokine ligand (CCL)21 is sufficient for attracting naive T cells into tertiary organs. We performed intravital microscopy of cremaster muscle venules in T-GFP mice, in which naive T cells express green fluorescent protein (GFP). GFP+ cells underwent selectin-dependent rolling, but no firm adherence (sticking). Superfusion with CCL21, but not CXC chemokine ligand 12, induced integrin-dependent sticking of GFP+ cells. Moreover, CCL21 rapidly elicited accumulation of naive T cells into sterile s.c. air pouches. Interestingly, a second CCR7 ligand, CCL19, triggered T cell sticking in cremaster muscle venules, but failed to induce extravasation in air pouches. Immunohistochemistry studies implicate ectopic expression of CCL21 as a mechanism for naive T cell traffic in human autoimmune diseases. Most blood vessels in tissue samples from patients with rheumatoid arthritis (85 ± 10%) and ulcerative colitis (66 ± 1%) expressed CCL21, and many perivascular CD45RA+ naive T cells were found in these tissues, but not in psoriasis, where CCL21+ vessels were rare (17 ± 1%). These results identify endothelial CCL21 expression as an important determinant for naive T cell migration to tertiary tissues, and suggest the CCL21/CCR7 pathway as a therapeutic target in diseases that are associated with naive T cell recruitment.
A Role of CXC Chemokine Ligand 12/Stromal Cell-Derived Factor-1/Pre-B Cell Growth Stimulating Factor and Its Receptor CXCR4 in Fetal and Adult T Cell Development in Vivo
Authors: Ara Toshiaki , Itoi Manami , Kawabata Kenji , Egawa Takeshi , Tokoyoda Koji , Sugiyama Tatsuki , Fujii Nobutaka , Amagai Takashi , Nagasawa Takashi 
Published: April 2014

AbstractThe functions of a chemokine CXC chemokine ligand (CXCL) 12/stromal cell-derived factor-1/pre-B cell growth stimulating factor and its physiologic receptor CXCR4 in T cell development are controversial. In this study, we have genetically further characterized their roles in fetal and adult T cell development using mutant and chimeric mice. In CXCL12−/− or CXCR4−/− embryos on a C57BL/6 background, accumulation of T cell progenitors in the outer mesenchymal layer of the thymus anlage during initial colonization of the fetal thymus was comparable with that seen in wild-type embryos. However, the expansion of CD3−CD4−CD8− triple-negative T cell precursors at the CD44−CD25+ and CD44−CD25− stages, and CD4+CD8+ double-positive thymocytes was affected during embryogenesis in these mutants. In radiation chimeras competitively repopulated with CXCR4−/− fetal liver cells, the reduction in donor-derived thymocytes compared with wild-type chimeras was much more severe than the reduction in donor-derived myeloid lineage cells in bone marrow. Triple negative CD44+CD25+ T cell precursors exhibited survival response to CXCL12 in the presence of stem cell factor as well as migratory response to CXCL12. Thus, it may be that CXCL12 and CXCR4 are involved in the expansion of T cell precursors in both fetal and adult thymus in vivo. Finally, enforced expression of bcl-2 did not rescue impaired T cell development in CXCR4−/− embryos or impaired reconstitution of CXCR4−/− thymocytes in competitively repopulated mice, suggesting that defects in T cell development caused by CXCR4 mutation are not caused by reduced expression of bcl-2.
Maternal Autoantibody Triggers De Novo T Cell-Mediated Neonatal Autoimmune Disease
Authors: Setiady Yulius Y. , Samy Eileen T. , Tung Kenneth S. K. 
Published: April 2014

AbstractAlthough human maternal autoantibodies may transfer transient manifestation of autoimmune disease to their progeny, some neonatal autoimmune diseases can progress, leading to the loss of tissue structure and function. In this study we document that murine maternal autoantibody transmitted to progeny can trigger de novo neonatal pathogenic autoreactive T cell response and T cell-mediated organ-specific autoimmune disease. Autoantibody to a zona pellucida 3 (ZP3) epitope was found to induce autoimmune ovarian disease (AOD) and premature ovarian failure in neonatal, but not adult, mice. Neonatal AOD did not occur in T cell-deficient pups, and the ovarian pathology was transferable by CD4+ T cells from diseased donors. Interestingly, neonatal AOD occurred only in pups exposed to ZP3 autoantibody from neonatal days 1–5, but not from day 7 or day 9. The disease susceptibility neonatal time window was not related to a propensity of neonatal ovaries to autoimmune inflammation, and it was not affected by infusion of functional adult CD4+CD25+ T cells. However, resistance to neonatal AOD in 9-day-old mice was abrogated by CD4+CD25+ T cell depletion. Finally, neonatal AOD was blocked by Ab to IgG-FcR, and interestingly, the disease was not elicited by autoantibody to a second, independent native ZP3 B cell epitope. Therefore, a new mechanism of neonatal autoimmunity is presented in which epitope-specific autoantibody stimulates de novo autoimmune pathogenic CD4+ T cell response.
Endogenous IL-17 as a Mediator of Neutrophil Recruitment Caused by Endotoxin Exposure in Mouse Airways
Authors: Miyamoto Masahide , Prause Olof , Sjöstrand Margareta , Laan Martti , Lötvall Jan , Lindén Anders 
Published: April 2014

AbstractWe have previously demonstrated that administration of the recently described cytokine IL-17 in rat airways in vivo recruits and activates neutrophils locally. In the current study, we examined whether endogenous IL-17 is involved in mediating neutrophil recruitment caused by endotoxin exposure in mouse airways. Our in vivo data show that local endotoxin exposure causes the release of free, soluble IL-17 protein 6 h later. Systemic pretreatment with a neutralizing anti-IL-17 Ab almost completely inhibits neutrophil recruitment 24 h, but not 6 h, after endotoxin exposure in the airways. Pretreatment with neutralizing anti-IL-6 and anti-macrophage inflammatory protein (MIP)-2 Abs inhibits neutrophil recruitment caused by local endotoxin exposure and IL-17, respectively. Our in vitro data show that endotoxin exposure stimulates the release of soluble IL-17 protein in T lymphocytes harvested from lung and spleen, respectively, and that this cytokine release requires coculture with airway macrophages. Intracellular IL-17 protein is detected in T lymphocytes from spleen but not in airway macrophages after coculture and stimulation of these two cell types. Finally, anti-IL-17 does not alter endotoxin-induced release of IL-6 and MIP-2 from T lymphocytes and airway macrophages in coculture. In conclusion, our results indicate that endotoxin exposure causes the release of IL-17 from T lymphocytes and that this cytokine release requires the presence of macrophages. Once released, endogenous IL-17 acts in part by inducing local release of neutrophil-mobilizing cytokines such as IL-6 and MIP-2, from nonlymphocyte, nonmacrophage cells, and this contributes to recruitment of neutrophils in the airways. These IL-17-related mechanisms constitute potential targets for pharmacotherapy against exaggerated neutrophil recruitment in airway disease.
The Paradox of Immune Molecular Recognition of α-Galactosylceramide: Low Affinity, Low Specificity for CD1d, High Affinity for αβ TCRs
Authors: Cantu Carlos , Benlagha Kamel , Savage Paul B. , Bendelac Albert , Teyton Luc 
Published: April 2014

Abstract
CD1 resembles both class I and class II MHC but differs by the important aspect of presenting lipid/glycolipids, instead of peptides, to T cells. Biophysical studies of lipid/CD1 interactions have been limited, and kinetics of binding are in contradiction with functional studies. We have revisited this issue by designing new assays to examine the loading of CD1 with lipids. As expected for hydrophobic interactions, binding affinity was not high and had limited specificity. Lipid critical micelle concentration set the limitation to these studies. Once loaded onto CD1d, the recognition of glycolipids by αβ T cell receptor was studied by surface plasmon resonance using soluble Vα14-Vβ8.2 T cell receptors. The Vα14 Jα18 chain could be paired with NK1.1 cell-derived Vβ chain, or any Vβ8 chain, to achieve high affinity recognition of α-galactosylceramide. Biophysical analysis indicated little effect of temperature or ionic strength on the binding interaction, in contrast to what has been seen in peptide/MHC-TCR studies. This suggests that there is less accommodation made by this TCR in recognizing α-galactosylceramide, and it can be assumed that the most rigid part of the Ag, the sugar moiety, is critical in the interaction.