bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of HLA Class II/Peptide-TCR Interactions of the Immunodominant T Cell Epitope in Art v 1, the Major Mugwort Pollen Allergen
Authors: Jahn-Schmid Beatrice , Sirven Philémon , Leb Victoria , Pickl Winfried F. , Fischer Gottfried F. , Gadermaier Gabriele , Egger Matthias , Ebner Christof , Ferreira Fatima , Maillére Bernard , Bohle Barbara 
Published: April 2014

AbstractMore than 95% of mugwort pollen-allergic individuals are sensitized to Art v 1, the major allergen in mugwort pollen. Interestingly, the CD4 T cell response to Art v 1 involves only one single immunodominant peptide, Art v 125–36 (KCIEWEKAQHGA), and is highly associated with the expression of HLA-DR1. Therefore, we investigated the molecular basis of this unusual immunodominance among allergens. Using artificial APC expressing exclusively HLA-DRB1*0101 and HLA-DRA*0101, we formally showed that DR1 acts as restriction element for Art v 125–36-specific T cell responses. Further assessment of binding of Art v 125–36 to artificial HLA-DR molecules revealed that its affinity was high for HLA-DR1. Amino acid I27 was identified as anchor residue interacting with DR molecules in pocket P1. Additionally, Art v 125–36 bound with high affinity to HLA-DRB1*0301 and *0401, moderately to HLA-DRB1*1301 and HLA-DRB5*0101, and weakly to HLA-DRB1*1101 and *1501. T cell activation was also inducible by Art v 125–36-loaded, APC-expressing HLA molecules other than DR1, indicating degeneracy of peptide binding and promiscuity of TCR recognition. Specific binding of HLA-DRB1*0101 tetramers containing Art v 119–36 allowed the identification of Art v 125–36-specific T cells by flow cytometry. In summary, the immunodominance of Art v 125–36 relies on its affinity to DR1, but is not dictated by it. Future investigations at the molecular HLA/peptide/TCR and cellular level using mugwort pollen allergy as a disease model may allow new insights into tolerance and pathomechanisms operative in type I allergy, which may instigate new, T cell-directed strategies in specific immunotherapy.
Memory B Cells and Pneumococcal Antibody After Splenectomy
Authors: Wasserstrom Heather , Bussel James , Lim Lony C.-L. , Cunningham-Rundles Charlotte 
Published: April 2014

Abstract
Splenectomized patients are susceptible to bloodstream infections with encapsulated bacteria, potentially due to loss of blood filtering but also defective production of anticarbohydrate Ab. Recent studies propose that a lack of Ab is related to reduced numbers of IgM+ CD27+ memory B cells found after splenectomy. To test this, we analyzed CD27+ memory B cell subsets, IgG, and IgM pneumococcal Ab responses in 26 vaccinated splenectomized subjects in comparison to memory B cell subsets and Ab responses in healthy controls. As shown previously, the splenectomized autoimmune subjects had fewer total, isotype switched, and IgM+ CD27+ memory B cells as compared with controls, but there was no difference in memory B cells subsets between controls and splenectomized subjects with spherocytosis. There was no difference between the geometric mean IgG Ab response between normal controls and splenectomized subjects (p = 0.51; p = 0.81). Control subjects produced more IgM Ab than splenectomized autoimmune subjects (p = 0.01) but the same levels as subjects with spherocytosis (p = 0.15.) There was no correlation between memory B cell subsets and IgG or IgM Ab responses for controls or splenectomized subjects. These data suggest that splenectomy alone may not be the sole reason for loss of memory B cells and reduced IgM antipneumococcal Ab. Because subjects with autoimmunity had splenectomy at a significantly older age than participants with spherocytosis, these data suggest that an age-related loss of extra splenic sites necessary for the maintenance or function of memory B cells may lead to impaired immunity in these subjects.
TGF-β Utilizes SMAD3 to Inhibit CD16-Mediated IFN-γ Production and Antibody-Dependent Cellular Cytotoxicity in Human NK Cells
Authors: Trotta Rossana , Col Jessica Dal , Yu Jianhua , Ciarlariello David , Thomas Brittany , Zhang Xiaoli , Allard Jeffrey , Wei Min , Mao Hsiaoyin , Byrd John C. , Perrotti Danilo , Caligiuri Michael A. 
Published: April 2014

Abstract
TGF-β can be a potent suppressor of lymphocyte effector cell functions and can mediate these effects via distinct molecular pathways. The role of TGF-β in regulating CD16-mediated NK cell IFN-γ production and antibody-dependent cellular cytotoxicity (ADCC) is unclear, as are the signaling pathways that may be utilized. Treatment of primary human NK cells with TGF-β inhibited IFN-γ production induced by CD16 activation with or without IL-12 or IL-2, and it did so without affecting the phosphorylation/activation of MAP kinases ERK and p38, as well as STAT4. TGF-β treatment induced SMAD3 phosphorylation, and ectopic overexpression of SMAD3 resulted in a significant decrease in IFN-γ gene expression following CD16 activation with or without IL-12 or IL-2. Likewise, NK cells obtained from smad3−/− mice produced more IFN-γ in response to CD16 activation plus IL-12 when compared with NK cells obtained from wild-type mice. Coactivation of human NK cells via CD16 and IL-12 induced expression of T-BET, the positive regulator of IFN-γ, and T-BET was suppressed by TGF-β and by SMAD3 overexpression. An extended treatment of primary NK cells with TGF-β was required to inhibit ADCC, and it did so by inhibiting granzyme A and granzyme B expression. This effect was accentuated in cells overexpressing SMAD3. Collectively, our results indicate that TGF-β inhibits CD16-mediated human NK cell IFN-γ production and ADCC, and these effects are mediated via SMAD3.
Plasmacytoid Dendritic Cells Take Up Opsonized Antigen Leading to CD4+ and CD8+ T Cell Activation In Vivo
Authors: Björck Pia , Beilhack Andreas , Herman Edward I. , Negrin Robert S. , Engleman Edgar G. 
Published: April 2014

Abstract
Plasmacytoid dendritic cells (pDC) are the body’s main source of IFN-α, but, unlike classical myeloid DC (myDC), they lack phagocytic activity and are generally perceived as playing only a minor role in Ag processing and presentation. We show that murine pDC, as well as myDC, express Fcγ receptors (CD16/CD32) and can use these receptors to acquire Ag from immune complexes (IC), resulting in the induction of robust Ag-specific CD4+ and CD8+ T cell responses. IC-loaded pDC stimulate CD4+ T cells to proliferate and secrete a mixture of IL-4 and IFN-γ, and they induce CD8+ T cells to secrete IL-10 as well as IFN-γ. In contrast, IC-loaded myDC induce both CD4+ and CD8+ T cells to secrete mainly IFN-γ. These results indicate that pDC can shape an immune response by acquiring and processing opsonized Ag, leading to a predominantly Th2 response.
Staphylococcus aureus-Induced Plasmacytoid Dendritic Cell Activation Is Based on an IgG-Mediated Memory Response
Authors: Parcina Marijo , Wendt Constanze , Goetz Friedrich , Zawatzky Rainer , Zähringer Ulrich , Heeg Klaus , Bekeredjian-Ding Isabelle 
Published: April 2014

Abstract
Type I IFNs represent a major antimicrobial defense mechanism due to their property of enhancing immune responses by priming both innate and adaptive immune cells. Plasmacytoid dendritic cells (pDC) are the major source of type I IFN in the human body and represent innate immune cells involved in first-line defense against invading pathogens. Although pDC activation has been extensively studied upon stimulation with synthetic TLR ligands, viruses, and intracellular bacteria, there is only scarce information on extracellular bacteria. In this study we show that the triggering of human pDC-derived IFN-α secretion by Staphylococcus aureus is independent of TLR2 and specific for coagulase-positive staphylococci. Specificity of the pDC response to S. aureus is independent of the bacterial virulence factors protein A and α-toxin but is mediated by Ag-specific IgG and CD32. S. aureus-induced pDC activation can be blocked by inhibitory DNA oligonucleotides and chloroquine, suggesting that engagement of TLR7/9 by bacterial nucleic acids after CD32-mediated uptake of these compounds may play a central role in this process. Altogether, we propose that in marked contrast to nonselective TLR2-dependent activation of most innate immune cells, pDC activation by S. aureus represents an Ag-specific memory response since it requires the presence of class-switched immunoglobulins.
TLR2 Expression in Astrocytes Is Induced by TNF-α- and NF-κB-Dependent Pathways
Authors: Phulwani Nirmal K. , Esen Nilufer , Syed Mohsin Md. , Kielian Tammy 
Published: April 2014

Abstract
Astrocytes participate in CNS innate immune responses as evident by their ability to produce a wide array of inflammatory mediators upon exposure to diverse stimuli. Although we have established that astrocytes use TLR2 to signal inflammatory mediator production in response to Staphylococcus aureus, a common etiological agent of CNS infections, the signal transduction pathways triggered by this pathogen and how TLR2 expression is regulated remain undefined. Three disparate inhibitors that block distinct steps in the NF-κB pathway, namely SC-514, BAY 11-7082, and caffeic acid phenethyl ester, attenuated NO, TNF-α, and CXCL2 release from S. aureus-activated astrocytes. Among these proinflammatory mediators, autocrine/paracrine TNF-α was pivotal for augmenting TLR2 expression, since receptor levels were not elevated in astrocytes isolated from TNF-α knockout mice upon bacterial exposure. Since TLR2 is critical for signaling astrocytic cytokine production in response to S. aureus, we evaluated the effect of TNF-α loss on proinflammatory mediator release. Interestingly, among the molecules assayed, only NO production was significantly attenuated in TNF-α knockout astrocytes compared with wild-type cells. Similar results were obtained following LPS treatment, suggesting that TNF-α is an important regulator of astrocytic TLR2 expression and NO release in response to diverse microbial stimuli. In addition, NF-κB inhibitors attenuated TNF-α-induced TLR2 expression in astrocytes. Overall, this study suggests that two important anti-bacterial effector molecules, TLR2 and NO, are regulated, in part, by NF-κB-dependent autocrine/paracrine effects of TNF-α in astrocytes.
High Sensitivity of Intestinal CD8+ T Cells to Nucleotides Indicates P2X7 as a Regulator for Intestinal T Cell Responses
Authors: Heiss Kirsten , Jänner Nathalie , Mähnß Birgit , Schumacher Valéa , Koch-Nolte Friedrich , Haag Friedrich , Mittrücker Hans-Willi 
Published: April 2014

Abstract
The purinoreceptor P2X7 is expressed on subsets of T cells and mediates responses of these cells to extracellular nucleotides such as ATP or NAD+. We identified P2X7 as a molecule highly up-regulated on conventional CD8αβ+ and unconventional CD8αα+ T cells of the intestinal epithelium of mice. In contrast, CD8+ T cells derived from spleen, mesenteric lymph nodes, and liver expressed only marginal levels of P2X7. However, P2X7 was highly up-regulated on CD8+ T cells from spleen and lymph nodes when T cells were activated in the presence of retinoic acid. High P2X7 expression on intestinal CD8+ T cells as well as on CD8+ T cells incubated with retinoic acid resulted in enhanced sensitivity of cells to extracellular nucleotides. Both cell populations showed a high level of apoptosis following incubation with NAD+ and the ATP derivative 2′,3′-O-(benzoyl-4-benzoyl)-ATP, and injection of NAD+ caused selective in vivo depletion of intestinal CD8+ T cells. Following oral infection with Listeria monocytogenes, P2X7-deficient mice showed similar CD8+ T cell responses in the spleen, but enhanced responses in the intestinal mucosa, when compared with similarly treated wild-type control mice. Overall, our observations define P2X7 as a new regulatory element in the control of CD8+ T cell responses in the intestinal mucosa.
CD8+ Th17 Mediate Costimulation Blockade-Resistant Allograft Rejection in T-bet-Deficient Mice
Authors: Burrell Bryna E. , Csencsits Keri , Lu Guanyi , Grabauskiene Svetlana , Bishop D. Keith 
Published: April 2014

Abstract
While studying Th responses induced by cardiac transplantation, we observed that mice deficient in the Th1 transcription factor T-bet (T-bet−/−) mount both Th1 and Th17 responses, whereas wild-type recipients mount only Th1 responses. Cells producing both IFN-γ and IL-17 were readily detectable within the rejecting graft of T-bet−/− recipients, but were absent from the spleen, indicating that the in vivo microenvironment influences Th function. In addition, disrupting CD40-CD40L costimulatory interactions was highly effective at prolonging allograft survival in WT mice, but ineffective in T-bet−/− recipients. In this study, we report that CD8+ Th17 mediate costimulation blockade-resistant rejection in T-bet−/− allograft recipients. Depleting CD8+ cells or neutralizing IL-17 or the Th17-inducing cytokine IL-6 ablated the Th17 response and reversed costimulation blockade-resistant graft rejection. Neutralizing IL-4 in IFN-γ−/− allograft recipients did not induce Th17, suggesting that T-bet, rather than IL-4 and IFN-γ (known inhibitors of Th17), plays a critical role in negatively regulating Th17 in the transplant setting.
Pretransplant Infusion of Mesenchymal Stem Cells Prolongs the Survival of a Semiallogeneic Heart Transplant through the Generation of Regulatory T Cells
Authors: Casiraghi Federica , Azzollini Nadia , Cassis Paola , Imberti Barbara , Morigi Marina , Cugini Daniela , Cavinato Regiane Aparecida , Todeschini Marta , Solini Samantha , Sonzogni Aurelio , Perico Norberto , Remuzzi Giuseppe , Noris Marina 
Published: April 2014

Abstract
In this study, we investigated whether mesenchymal stem cells (MSC) had immunomodulatory properties in solid organ allotransplantation, using a semiallogeneic heart transplant mouse model, and studied the mechanism(s) underlying MSC tolerogenic effects. Either single (portal vein, day −7) or double (portal vein, day −7 and tail vein, day −1) pretransplant infusions of donor-derived B6C3 MSC in B6 recipients induced a profound T cell hyporesponsiveness and prolonged B6C3 cardiac allograft survival. The protolerogenic effect was abrogated when donor-derived MSC were injected together with B6C3 hematopoietic stem cells (HSC), suggesting that HSC negatively impact MSC immunomodulatory properties. Both the induction (pretransplant) and the maintenance phase (&gt;100 days posttransplant) of donor-derived MSC-induced tolerance were associated with CD4+CD25+Foxp3+ Treg expansion and impaired anti-donor Th1 activity. MSC-induced regulatory T cells (Treg) were donor-specific since adoptive transfer of splenocytes from tolerant mice prevented the rejection of fully MHC-mismatched donor-specific secondary allografts but not of third-party grafts. In addition, infusion of recipient-derived B6 MSC tolerized a semiallogeneic B6C3 cardiac allograft, but not a fully MHC-mismatched BALB/c graft, and expanded Treg. A double i.v. pretransplant infusion of recipient-derived MSC had the same tolerogenic effect as the combined intraportal/i.v. MSC infusions, which makes the tolerogenic protocol applicable in a clinical setting. In contrast, single MSC infusions given either peritransplant or 1 day after transplant were less effective. Altogether these findings indicate that MSC immunomodulatory properties require HSC removal, partial sharing of MHC Ags between the donor and the recipient and pretransplant infusion, and are associated with expansion of donor-specific Treg.
Defects in Skin γδ T Cell Function Contribute to Delayed Wound Repair in Rapamycin-Treated Mice
Authors: Mills Robyn E. , Taylor Kristen R. , Podshivalova Katie , McKay Dianne B. , Jameson Julie M. 
Published: April 2014

Abstract
Disruptions in the normal program of tissue repair can result in poor wound healing, which perturbs the integrity of barrier tissues such as the skin. Such defects in wound repair occur in transplant recipients treated with the immunosuppressant drug rapamycin (sirolimus). Intraepithelial lymphocytes, such as γδ T cells in the skin, mediate tissue repair through the production of cytokines and growth factors. The capacity of skin-resident T cells to function during rapamycin treatment was analyzed in a mouse model of wound repair. Rapamycin treatment renders skin γδ T cells unable to proliferate, migrate, and produce normal levels of growth factors. The observed impairment of skin γδ T cell function is directly related to the inhibitory action of rapamycin on mammalian target of rapamycin. Skin γδ T cells treated with rapamycin are refractory to IL-2 stimulation and attempt to survive in the absence of cytokine and growth factor signaling by undergoing autophagy. Normal wound closure can be restored in rapamycin-treated mice by addition of the skin γδ T cell-produced factor, insulin-like growth factor-1. These studies not only reveal that mammalian target of rapamycin is a master regulator of γδ T cell function but also provide a novel mechanism for the increased susceptibility to nonhealing wounds that occurs during rapamycin administration.
Elevating Calcium in Th2 Cells Activates Multiple Pathways to Induce IL-4 Transcription and mRNA Stabilization
Authors: Guo Liying , Urban Joseph F. , Zhu Jinfang , Paul William E. 
Published: April 2014

Abstract
PMA and ionomycin cause T cell cytokine production. We report that ionomycin alone induces IL-4 and IFN-γ, but not IL-2, from in vivo- and in vitro-generated murine Th2 and Th1 cells. Ionomycin-induced cytokine production requires NFAT, p38, and calmodulin-dependent kinase IV (CaMKIV). Ionomycin induces p38 phosphorylation through a calcium-dependent, cyclosporine A-inhibitable pathway. Knocking down ASK1 inhibits ionomycin-induced p38 phosphorylation and IL-4 production. Ionomycin also activates CaMKIV, which, together with p38, induces AP-1. Cooperation between AP-1 and NFAT leads to Il4 gene transcription. p38 also regulates IL-4 production by mRNA stabilization. TCR stimulation also phosphorylates p38, partially through the calcium-dependent pathway; activated p38 is required for optimal IL-4 and IFN-γ.
SAP Enables T Cells to Help B Cells by a Mechanism Distinct from Th Cell Programming or CD40 Ligand Regulation
Authors: Kamperschroer Cris , Roberts Deborah M. , Zhang Yongqing , Weng Nan-ping , Swain Susan L. 
Published: April 2014

Abstract
Genetic mutations disrupting the function of signaling lymphocytic activation molecule-associated protein (SAP) lead to T cell intrinsic defects in T cell-dependent Ab responses. To better understand how SAP enables Th cells to help B cells, we first assessed whether molecules important for B cell help are dysregulated in SAP-deficient (SAP knockout (KO)) mice. CD40 ligand (CD40L) expression was enhanced on unpolarized SAP KO T cells; however, Th2 polarization returned their CD40L expression to wild-type levels without rescuing their ability to help B cells. CD40L also localized normally to the site of contact between SAP KO T cells and Ag-bearing B cells. Finally, CD40L-deficient Th cells and SAP KO Th cells differed in their abilities to help B cells in vitro. These data argue that Ab defects caused by SAP deficiency do not result from a loss of CD40L regulation or CD40L function on CD4 T cells. SAP KO Th cells additionally displayed normal patterns of migration and expression of ICOS and CXCR5. Global gene expression was remarkably similar in activated SAP KO vs wild-type T cells, prompting us to investigate whether SAP is necessary for “programming” T cells to become B cell helpers. By restricting SAP expression during differentiation, we determined that SAP is not required during the first 5 days of T cell activation/differentiation to generate Th cells capable of helping B cells. Instead, SAP is necessary for very late stages of differentiation or, most likely, for allowing Th cells to communicate during cognate T:B interactions.
Effector Mechanisms of the Autoimmune Syndrome in the Murine Model of Autoimmune Polyglandular Syndrome Type 1
Authors: DeVoss Jason J. , Shum Anthony K. , Johannes Kellsey P. A. , Lu Wen , Krawisz Anna K. , Wang Peter , Yang Ting , LeClair Norbert P. , Austin Cecilia , Strauss Erich C. , Anderson Mark S. 
Published: April 2014

Abstract
Mutations in the Aire gene result in a clinical phenomenon known as Autoimmune Polyglandular Syndrome (APS) Type I, which classically manifests as a triad of adrenal insufficiency, hypoparathyroidism, and chronic mucocutaneous infections. In addition to this triad, a number of other autoimmune diseases have been observed in APS1 patients including Sjögren’s syndrome, vitiligo, alopecia, uveitis, and others. Aire-deficient mice, the animal model for APS1, have highlighted the role of the thymus in the disease process and demonstrated a failure in central tolerance in aire-deficient mice. However, autoantibodies have been observed against multiple organs in both mice and humans, making it unclear what the specific role of B and T cells are in the pathogenesis of disease. Using the aire-deficient mouse as a preclinical model for APS1, we have investigated the relative contribution of specific lymphocyte populations, with the goal of identifying the cell populations which may be targeted for rational therapeutic design. In this study, we show that T cells are indispensable to the breakdown of self-tolerance, in contrast to B cells which play a more limited role in autoimmunity. Th1 polarized CD4+ T cells, in particular, are major contributors to the autoimmune response. With this knowledge, we go on to use therapies targeted at T cells to investigate their ability to modulate disease in vivo. Depletion of CD4+ T cells using a neutralizing Ab ameliorated the disease process. Thus, therapies targeted specifically at the CD4+ T cell subset may help control autoimmune disease in patients with APS1.
An Atypical NF-κB-Regulated Pathway Mediates Phorbol Ester-Dependent Heme Oxygenase-1 Gene Activation in Monocytes
Authors: Naidu Srivatsava , Wijayanti Nastiti , Santoso Sentot , Kietzmann Thomas , Immenschuh Stephan 
Published: April 2014

AbstractHeme oxygenase (HO)-1 catalyzes the rate-limiting step of heme degradation and plays an important anti-inflammatory role via its enzymatic products carbon monoxide and biliverdin. In this study it is reported that the HO-1 gene is transcriptionally induced by the phorbol ester PMA in cell cultures of monocytic cells with a regulatory pattern that is different from that of LPS-dependent HO-1 induction in these cells. Activation of HO-1 by PMA was mediated via a newly identified κB element of the proximal rat HO-1 gene promoter region (−284 to −275). This HO-κB element was a nuclear target for the NF-κB subunit p65/RelA as determined by nuclear binding assays and transfection experiments with luciferase reporter gene constructs in RAW264.7 monocytes. Moreover, PMA-dependent induction of endogenous HO-1 gene expression and promoter activity was abrogated in embryonic fibroblasts from p65−/− mice. PMA-dependent HO-1 gene activation was reduced by an overexpressed dominant negative mutant of IκBα, but not by dominant negative IκB kinase-2, suggesting that the classical NF-κB pathway was not involved in this regulation. The antioxidant N-acetylcysteine and inhibitors of p38 MAPK or serine/threonine kinase CK2 blocked PMA-dependent HO-1 gene activation. Finally, it is demonstrated by luciferase assays with a Gal4-CHOP fusion protein that the activation of p38 MAPK by PMA was independent of CK2. Taken together, induction of HO-1 gene expression by PMA is regulated via an IκB kinase-independent, atypical NF-κB pathway that is mediated via the activation of p38 MAPK and CK2.