bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selective Delivery of Augmented IL-2 Receptor Signals to Responding CD8+ T Cells Increases the Size of the Acute Antiviral Response and of the Resulting Memory T Cell Pool
Authors: Cheng Laurence E. , Greenberg Philip D. 
Published: April 2014

Abstract
CD8+ T cells respond to IL-2 produced both endogenously and by CD4+ Th during an antiviral response. However, IL-2R signals can potentially promote CD8+ T cell death as well as proliferation, making it unclear whether IL-2R signals provide a predominantly positive or negative effect upon CD8+ T cell responses to viral infection. To more precisely define the direct role of IL-2R signaling on CD8+ T cells during the response to a virus, we examined the effect of delivering augmented IL-2R signals selectively to CD8+ T cells responding to lymphocytic choriomeningitis virus infection. Although naive CD8+ T cells are competent to produce IL-2, CD8+ T cells lose this capacity upon differentiation into effector CD8+ T cells. However, effector CD8+ T cells do retain the capacity to produce GM-CSF upon Ag stimulation. Thus, to deliver enhanced autocrine IL-2R signals to CD8+ T cells, we established a transgenic mouse strain expressing a chimeric GM-CSF/IL-2R (GMIL2R). As GM-CSF production is Ag dependent, the GMIL2R delivers an augmented IL-2R signal exclusively to CD8+ T cells responding to Ag. Following lymphocytic choriomeningitis virus infection, GMIL2R transgenic mice exhibited an increase in both the peak CD8+ T cell response achieved and the size of the resulting memory pool established. Upon secondary viral challenge, the GMIL2R also enhanced the proliferative response of memory CD8+ T cells. Thus, our findings indicate that IL-2 delivery to responding CD8+ T cells is a limiting factor in both the acute and memory antiviral responses.
A Positive Regulatory Role for Suppressor of Cytokine Signaling 1 in IFN-γ-Induced MHC Class II Expression in Fibroblasts
Authors: Ilangumaran Subburaj , Finan Dina , La Rose José , Raine Jason , Silverstein Anna , De Sepulveda Paulo , Rottapel Robert 
Published: April 2014

Abstract
Suppressor of cytokine signaling 1 (SOCS1) is rapidly induced following stimulation by several cytokines. SOCS1 negatively regulates cytokine receptor signal transduction by inhibiting Janus family tyrosine kinases. Lack of such feedback regulation underlies the premature death of SOCS1−/− mice due to unbridled IFN-γ signaling. We used mouse embryo fibroblasts derived from SOCS1−/− mice to investigate the role of SOCS1 in IFN-γ signaling pathways. SOCS1−/− fibroblasts were exquisitely sensitive to the IFN-γ-mediated growth arrest and showed sustained STAT1 phosphorylation. However, SOCS1−/− fibroblasts were inefficient in MHC class II surface expression following IFN-γ stimulation, despite a marked induction of the MHC class II transactivator and MHC class II gene expression. Retroviral transduction of wild-type SOCS1 relieved the growth-inhibitory effects of IFN-γ in SOCS1−/− fibroblasts by inhibiting STAT1 activation. SOCS1R105K, carrying a mutation within the phosphotyrosine-binding pocket of the Src homology 2 domain, did not inhibit STAT1 phosphorylation, yet considerably inhibited IFN-γ-mediated growth arrest. Strikingly, expression of SOCS1R105K restored the IFN-γ-induced MHC class II expression in SOCS1−/− cells, indicating that expression of SOCS1 facilitates MHC class II expression in fibroblasts. Our results show that SOCS1, in addition to its negative regulatory role of inhibiting Janus kinases, has an unanticipated positive regulatory function in retarding the degradation of IFN-γ-induced MHC class II proteins in fibroblasts.
The β2-Adrenergic Agonist Salbutamol Potentiates Oral Induction of Tolerance, Suppressing Adjuvant Arthritis and Antigen-Specific Immunity
Authors: Cobelens Pieter M. , Kavelaars Annemieke , Vroon Anne , Ringeling Marion , van der Zee Ruurd , van Eden Willem , Heijnen Cobi J. 
Published: April 2014

AbstractTherapeutic protocols for treating autoimmune diseases by feeding autoantigens during the disease process have not been very successful to date. In vitro it has been shown that β-adrenergic agonists inhibit pro-inflammatory cytokine production and up-regulate anti-inflammatory cytokine production. We hypothesized that the protective effect of oral administration of Ag would be enhanced by oral coadministration of the β2-adrenergic agonist salbutamol. Here we demonstrate that oral administration of salbutamol in combination with the Ag mycobacterial 65-kDa heat shock protein increased the efficacy of disease-suppressive tolerance induction in rat adjuvant arthritis. To study the mechanism of salbutamol in more detail, we also tested oral administration of salbutamol in an OVA tolerance model in BALB/c mice. Oral coadministration of OVA/salbutamol after immunization with OVA efficiently suppressed both cellular and humoral responses to OVA. Coadministration of salbutamol was associated with an immediate increase in IL-10, TGF-β, and IL-1R antagonist in the intestine. The tolerizing effect of salbutamol/OVA was maintained for at least 12 wk. At this time point IFN-γ production in Ag-stimulated splenocytes was increased in the OVA/salbutamol-treated animals. In conclusion, salbutamol can be of great clinical benefit for the treatment of autoimmune diseases by promoting oral tolerance induction.
Dynamic Association of CD45 with Detergent-Insoluble Microdomains in T Lymphocytes
Authors: Edmonds Stuart D. , Ostergaard Hanne L. 
Published: April 2014

Abstract
The receptor-like protein tyrosine phosphatase CD45 is essential for TCR signal transduction. Substrates of CD45 include the protein tyrosine kinases p56lck and p59fyn, both of which have been shown to be enriched in detergent-insoluble microdomains. Here we find that there is a cholesterol-dependent association between CD45 and the raft-associated protein linker for activation of T cells, suggesting that CD45 and linker for activation of T cells may colocalize in lipid rafts. Consistent with this observation, we find that ∼5% of total CD45 can be detected in Triton X-100-insoluble buoyant fractions of sucrose gradients, demonstrating that CD45 is not excluded from lipid rafts. Upon stimulation of T cells with anti-CD3, there is a reduction in the amount of CD45 found associating with lipid rafts. Our data suggest that CD45 is present in lipid rafts in T cells before activation, perhaps to activate raft-associated p56lck, allowing membrane-proximal signaling events to proceed. Furthermore, the reduction in CD45 content of lipid rafts after CD3 stimulation may serve to limit the amounts of activated p56lck in rafts and thus possibly the duration of T cell responses.
HLA-DR4 Molecules in Neuroendocrine Epithelial Cells Associate to a Heterogeneous Repertoire of Cytoplasmic and Surface Self Peptides
Authors: Muntasell Aura , Carrascal Montserrat , Serradell Laurence , Veelen Peter van , Verreck Frank , Koning Frits , Raposo Graça , Abián Joaquín , Jaraquemada Dolores 
Published: April 2014

AbstractExpression of MHC class II genes by epithelial cells is induced in inflammatory conditions such as autoimmunity and organ transplantation. Class II ligands generated by the epithelial cell processing mechanisms are unknown, although some unique epitopes have been described in epithelial cells that B cells could not generate. Epithelial cells are the targets of autoreactive T cell responses in autoimmune diseases and of transplant rejection processes, which may involve recognition of cell type-specific epitopes. In the present report, we have compared the DR4-associated repertoire and the intracellular distribution of class II, invariant chain (Ii), and DM molecules between a human DR4-, Ii-, and DM-transfected rat neuroendocrine epithelial cell line and a homozygous DR4 (DRB1*0401) lymphoblastoid B cell line, by mass spectrometry sequencing techniques, and immunoelectron microscopy. The epithelial cells chosen for transfection, RINm5F, are rat insular cells widely used for human studies of autoimmune diabetes. The results revealed a remarkably heterogeneous pool of self protein-derived peptides from the cell surface and various intracellular compartments, including the cytosol and secretory vesicles in epithelial cells, compared with a very restricted homogeneous repertoire in lymphoblastoid B cell lines, where few epitopes from surface molecules were predominant. The generation of distinct DR4-associated peptide repertoires in these two cell types could be due to the effect of several factors including differences in subcellular location of Ii and DM molecules, differential DO expression, and cell type-specific mechanisms of class II ligand generation. This is specially relevant to processes involving epithelial T cell interactions such as organ-specific autoimmunity and transplant rejection.
Cysteine Residues Required for the Attachment of the Light Chain in Human IgA2
Authors: Chintalacharuvu Koteswara R. , Yu Li J. , Bhola Nishant , Kobayashi Kunihiko , Fernandez Christine Z. , Morrison Sherie L. 
Published: April 2014

AbstractIn humans, there are two subclasses of IgA, IgA1 and IgA2, with IgA2 existing as three allotypes, IgA2m(1), IgA2m(2) and IgA2(n). In IgA1, Cys133 in CH1 forms the disulfide bond to the L chain. Our previous studies indicated that in IgA2 lacking Cys133, a disulfide bond forms between the α-chain and the L chain when Cys220 is followed by Arg221, but not when Cys220 is followed by Pro221, suggesting that the Cys in CH1 might be involved in disulfide bonding to the L chain. However, here we show that covalent assembly of the H and L chains in IgA2(n) requires hinge-proximal Cys241 and Cys242 in CH2 and not Cys196 or Cys220 in CH1. Using pulse-chase experiments, we have demonstrated that wild-type IgA2(n) with Arg221 and Cys241 and Cys242 assembles through a disulfide-bonded HL intermediate. In contrast, the major intermediate for IgA2 m(1) with Pro221 assembly was H2 even though both Cys241 and Cys242 were present. Only a small fraction of IgA2 m(1) assembles through disulfide-bonded HL. Overall, our studies indicate that for IgA2 covalent assembly of the H and L chains requires the hinge-proximal cysteines in CH2 and that the structure of CH1 influences the efficiency with which this covalent bond forms.
Inhibition of HIV-1 Infection by Small Interfering RNA-Mediated RNA Interference
Authors: Capodici John , Karikó Katalin , Weissman Drew 
Published: April 2014

Abstract
RNA interference (RNAi) is an ancient antiviral response that processes dsRNA and associates it into a nuclease complex that identifies RNA with sequence homology and specifically cleaves it. We demonstrate that RNAi mediated by 21-bp dsRNA specifically inhibits HIV-1 infection of permanent cell lines and primary CD4+ T cells. Inhibition of HIV replication was measured by p24 Gag protein content in supernatant, Northern blot analysis, and DNA PCR for products of reverse transcription. The inhibition occurred at two points in the viral life cycle, after fusion and before reverse transcription and during transcription of viral RNA from integrated provirus. Treatment of HIV-infected activated CD4+ T cells with a fluorine-derivatized siRNA that is resistant to RNase A yielded similar inhibition of HIV infection. In addition, the derivatized siRNA could be delivered without lipofectin complexing and in the presence of serum. The identification of RNAi activity against HIV-1 presents a new approach to study viral infections and a proof of concept of RNAi antiviral activity in mammalian cells.
Dysregulation of LPS-Induced Toll-Like Receptor 4-MyD88 Complex Formation and IL-1 Receptor-Associated Kinase 1 Activation in Endotoxin-Tolerant Cells
Authors: Medvedev Andrei E. , Lentschat Arnd , Wahl Larry M. , Golenbock Douglas T. , Vogel Stefanie N. 
Published: April 2014

Abstract
Prior exposure to LPS induces a transient state of cell refractoriness to subsequent LPS restimulation, known as endotoxin tolerance. Induction of LPS tolerance has been reported to correlate with decreased cell surface expression of the LPS receptor complex, Toll-like receptor 4 (TLR4)/MD-2. However, other results have underscored the existence of mechanisms of LPS tolerance that operate downstream of TLR4/MD-2. In the present study we sought to delineate further the molecular basis of LPS tolerance by examining the TLR4 signaling pathway in endotoxin-tolerant cells. Pretreatment of human monocytes with LPS decreased LPS-mediated NF-κB activation, p38 mitogen-activated protein kinase phosphorylation, and TNF-α gene expression, documenting the induction of endotoxin tolerance. FACS and Western blot analyses of LPS-tolerant monocytes showed increased TLR2 expression, whereas TLR4 expression levels were not affected. Comparable levels of mRNA and protein for myeloid differentiation factor 88 (MyD88), IL-1R-associated kinase 1 (IRAK-1), and TNFR-associated factor-6 were found in normal and LPS-tolerant monocytes, while MD-2 mRNA expression was slightly increased in LPS-tolerant cells. LPS induced the association of MyD88 with TLR4 and increased IRAK-1 activity in medium-pretreated cells. In LPS-tolerant monocytes, however, MyD88 failed to be recruited to TLR4, and IRAK-1 was not activated in response to LPS stimulation. Moreover, endotoxin-tolerant CHO cells that overexpress human TLR4 and MD-2 also showed decreased IRAK-1 kinase activity in response to LPS despite the failure of LPS to inhibit cell surface expression of transfected TLR4 and MD-2 proteins. Thus, decreased TLR4-MyD88 complex formation with subsequent impairment of IRAK-1 activity may underlie the LPS-tolerant phenotype.
Tumor Cell Lysate-Pulsed Dendritic Cells Are More Effective Than TCR Id Protein Vaccines for Active Immunotherapy of T Cell Lymphoma
Authors: Gatza Erin , Okada Craig Y. 
Published: April 2014

Abstract
TCR Id protein conjugated to keyhole limpet hemocyanin (KLH) (TCR Id:KLH) and injected with a chemical adjuvant (QS-21) induces a protective, Id-specific immune response against the murine T cell lymphoma, C6VL. However, Id-based immunotherapy of C6VL has not demonstrated therapeutic efficacy in tumor-bearing mice. We report here that C6VL lysate-pulsed dendritic cells (C6VL-DC) vaccines display enhanced efficacy in both the prevention and the therapy of T cell lymphoma compared with TCR Id:KLH with QS-21 vaccines. C6VL-DC vaccines stimulated potent tumor-specific immunity that protected mice against lethal challenge with C6VL and significantly enhanced the survival of tumor-bearing mice. Tumor-specific proliferation and secretion of IFN-γ indicative of a Th1-type immune response were observed upon ex vivo stimulation of vaccine-primed lymph node cells. Adoptive transfer of immune T cell-enriched lymphocytes was sufficient to protect naive recipients from lethal tumor challenge. Furthermore, CD8+ T cells were absolutely required for tumor protection. Although C6VL-DC and control vaccines stimulated low levels of tumor-specific Ab production in mice, Ab levels did not correlate with the protective ability of the vaccine. Thus, tumor cell lysate-pulsed DC vaccines appear to be an effective approach to generate potent T cell-mediated immune responses against T cell malignancies without requiring identification of tumor-specific Ags or patient-specific Id protein expression.
Lymphotoxin-α-Deficient Mice Make Delayed, But Effective, T and B Cell Responses to Influenza
Authors: Lund Frances E. , Partida-Sánchez Santiago , Lee Byung O. , Kusser Kimberly L. , Hartson Louise , Hogan Robert J. , Woodland David L. , Randall Troy D. 
Published: April 2014

Abstract
Lymphotoxin-α−/− (LTα−/−) mice are thought to be unable to generate effective T and B cell responses. This is attributed to the lack of lymph nodes and the disrupted splenic architecture of these mice. However, despite these defects we found that LTα−/− mice could survive infection with a virulent influenza A virus. LTα−/− mice and normal wild-type mice infected with influenza A generated similar numbers of influenza-specific CD8 T cells that were able to produce IFN-γ and kill target cells presenting influenza peptides. Furthermore influenza-infected LTα−/− mice produced high titers of influenza-specific IgM, IgG, and IgA. However, both CD8 and B cell immune responses were delayed in LTα−/− mice by 2–3 days. The delayed cellular and humoral immune response was sufficient to mediate viral clearance in LTα−/− mice that were infected with relatively low doses of influenza virus. However, when LTα−/− mice were infected with larger doses of influenza, they succumbed to infection before the immune response was initiated. These results demonstrate that neither LTα nor constitutively organized lymphoid tissues, such as lymph nodes and spleen, are absolutely required for the generation of effective immunity against the respiratory virus influenza A. However, the presence of LTα and/or lymph nodes does accelerate the initiation of immune responses, which leads to protection from larger doses of virus.
Platelet-Activating Factor Activates Two Distinct Effector Pathways in Human Eosinophils
Authors: Kato Masahiko , Kimura Hirokazu , Motegi Youichi , Tachibana Atsushi , Minakami Hisanori , Morikawa Akihiro , Kita Hirohito 
Published: April 2014

Abstract
In granulocytes, platelet-activating factor (PAF) shares many of its biological effects with other chemotactic factors, such as FMLP, complement fragments, and lipid mediators. Two unique effects are that PAF is relatively resistant to pertussis toxin (PTX) and that PAF activates the inflammatory functions of eosinophils more strongly than it activates those of neutrophils. To investigate the molecular mechanisms of the responses of eosinophils to PAF, we analyzed superoxide anion production by a chemiluminescence method that provides real-time kinetic data for the cellular responses. We found that PAF induced bimodal superoxide anion production in human eosinophils, consisting of an intense, but transient, first phase and a larger and sustained second phase. In contrast, PAF induced essentially a transient unimodal response in human neutrophils. The two phases of eosinophil response were mediated by distinct cellular mechanisms: the second phase was highly dependent on cellular adhesion and β2 integrins, but the first phase was independent of both adhesion and β2 integrins. The upstream signaling mechanisms were also different: the second phase was mediated by PTX-resistant G-protein(s) and through activation of phosphatidylinositol 3-kinase, while the first phase was mediated by PTX-sensitive G-protein(s). Furthermore, the second-phase response was ∼100-fold more resistant to inhibition by a competitive PAF receptor antagonist than the first phase. Thus, eosinophils and neutrophils react differently to PAF, and PAF activates two separate and distinct effector pathways in human eosinophils. These two activation pathways may explain the eosinophils’ strong and diverse biological responses to PAF.
TCRγδ+ and CD161+ Thymocytes Express HIV-1 in the SCID-hu Mouse, Potentially Contributing to Immune Dysfunction in HIV Infection
Authors: Gurney Kevin B. , Yang Otto O. , Wilson S. Brian , Uittenbogaart Christel H. 
Published: April 2014

Abstract
The vast diversity of the T cell repertoire renders the adaptive immune response capable of recognizing a broad spectrum of potential antigenic peptides. However, certain T cell rearrangements are conserved for recognition of specific pathogens, as is the case for TCRγδ cells. In addition, an immunoregulatory class of T cells expressing the NK receptor protein 1A (CD161) responds to nonpeptide Ags presented on the MHC-like CD1d molecule. The effect of HIV-1 infection on these specialized T cells in the thymus was studied using the SCID-hu mouse model. We were able to identify CD161-expressing CD3+ cells but not the CD1d-restricted invariant Vα24/Vβ11/CD161+ NK T cells in the thymus. A subset of TCRγδ cells and CD161-expressing thymocytes express CD4, CXCR4, and CCR5 during development in the thymus and are susceptible to HIV-1 infection. TCRγδ thymocytes were productively infectable by both X4 and R5 virus, and thymic HIV-1 infection induced depletion of CD4+ TCRγδ cells. Similarly, CD4+CD161+ thymocytes were depleted by thymic HIV-1 infection, leading to enrichment of CD4−CD161+ thymocytes. Furthermore, compared with the general CD4-negative thymocyte population, CD4−CD161+ NK T thymocytes exhibited as much as a 27-fold lower frequency of virus-expressing cells. We conclude that HIV-1 infection and/or disruption of cells important in both innate and acquired immunity may contribute to the overall immune dysfunction seen in HIV-1 disease.
Differential Regulation of Vitamin D Receptor and Its Ligand in Human Monocyte-Derived Dendritic Cells
Authors: Hewison Martin , Freeman Lisa , Hughes Susan V. , Evans Katie N. , Bland Rosemary , Eliopoulos Aristides G. , Kilby Mark D. , Moss Paul A. H. , Chakraverty Ronjon 
Published: April 2014

Abstract
The functions of dendritic cells (DCs) are tightly regulated such that protective immune responses are elicited and unwanted immune responses are prevented. 1α25-dihydroxyvitamin D3 (1α25(OH)2D3) has been identified as a major factor that inhibits the differentiation and maturation of DCs, an effect dependent upon its binding to the nuclear vitamin D receptor (VDR). Physiological control of 1α25(OH)2D3 levels is critically dependent upon 25-hydroxyvitamin D3-1α-hydroxylase (1αOHase), a mitochondrial cytochrome P450 enzyme that catalyzes the conversion of inactive precursor 25-hydroxyvitamin D3 (25(OH)D3) to the active metabolite 1α25(OH)2D3. Using a human monocyte-derived DC (moDC) model, we have examined the relationship between DC VDR expression and the impact of exposure to its ligand, 1α25(OH)2D3. We show for the first time that moDCs are able to synthesize 1α25(OH)2D3 in vitro as a consequence of increased 1αOHase expression. Following terminal differentiation induced by a diverse set of maturation stimuli, there is marked transcriptional up-regulation of 1αOHase leading to increased 1αOHase enzyme activity. Consistent with this finding is the observation that the development and function of moDCs is inhibited at physiological concentrations of the inactive metabolite 25(OH)D3. In contrast to 1αOHase, VDR expression is down-regulated as monocytes differentiate into immature DCs. Addition of 1α25(OH)2D3 to moDC cultures at different time points indicates that its inhibitory effects are greater in monocyte precursors than in immature DCs. In conclusion, differential regulation of endogenous 1α25(OH)2D3 ligand and its nuclear receptor appear to be important regulators of DC biology and represent potential targets for the manipulation of DC function.