bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adenosine Inhibits Macrophage Colony-Stimulating Factor-Dependent Proliferation of Macrophages Through the Induction of p27kip-1Expression
Authors: Xaus Jordi , Valledor Annabel F. , Cardó Marina , Marquès Laura , Beleta Jorge , Palacios José M. , Celada Antonio 
Published: December 2022

AbstractAdenosine is produced during inflammation and modulates different functional activities in macrophages. In murine bone marrow-derived macrophages, adenosine inhibits M-CSF-dependent proliferation with an IC50 of 45 μM. Only specific agonists that can activate A2B adenosine receptors such as 5′-N-ethylcarboxamidoadenosine, but not those active on A1 (N6-(R)-phenylisopropyladenosine), A2A ([p-(2-carbonylethyl)phenylethylamino]-5′-N-ethylcarboxamidoadenosine), or A3 (N6-(3-iodobenzyl)adenosine-5′-N-methyluronamide) receptors, induce the generation of cAMP and modulate macrophage proliferation. This suggests that adenosine regulates macrophage proliferation by interacting with the A2B receptor and subsequently inducing the production of cAMP. In fact, both 8-Br-cAMP (IC50 85 μM) and forskolin (IC50 7 μM) inhibit macrophage proliferation. Moreover, the inhibition of adenylyl cyclase and protein kinase A blocks the inhibitory effect of adenosine and its analogues on macrophage proliferation. Adenosine causes an arrest of macrophages at the G1 phase of the cell cycle without altering the activation of the extracellular-regulated protein kinase pathway. The treatment of macrophages with adenosine induces the expression of p27kip-1, a G1 cyclin-dependent kinase inhibitor, in a protein kinase A-dependent way. Moreover, the involvement of p27kip-1 in the adenosine inhibition of macrophage proliferation was confirmed using macrophages from mice with a disrupted p27kip-1 gene. These results demonstrate that adenosine inhibits macrophage proliferation through a mechanism that involves binding to A2B adenosine receptor, the generation of cAMP, and the induction of p27kip-1 expression.
Genetic Evidence for Lyn as a Negative Regulator of IL-4 Signaling
Authors: Janas Michelle L. , Hodgkin Philip , Hibbs Margaret , Tarlinton David 
Published: December 2022

Abstract
IL-4 has multiple effects on B lymphocytes, many of which are concentration dependent. This is particularly so for Ig isotype switching, where different thresholds of IL-4 stimulation are needed to induce switching from IgM to either IgG1 or IgE. In this report we describe a critical role for the tyrosine kinase Lyn in setting IL-4 signaling thresholds in mouse B lymphocytes. Upon CD40 ligand stimulation of lyn−/− B cells, 10-fold less IL-4 was required to induce switching from IgM to IgG1 and IgE and an increased proportion of B cells isotype switched at each IL-4 concentration. These in vitro results correlate with the in vivo findings that in lyn−/− mice, IgG1 Ab-forming cells develop prematurely in ontogeny and that adult lyn−/− mice have an abnormally high proportion of IgG1-expressing B cells in their spleens. Adult lyn−/− mice also have significantly higher levels of IgE in their serum. These results identify Lyn as a molecule involved in modulating the IL-4 signal in B cells and provide insights into its regulation and how a B cell signaling imbalance may contribute to atopy.
NK Cell Triggering by the Human Costimulatory Molecules CD80 and CD86
Authors: Wilson Julia L. , Charo Jehad , Martín-Fontecha Alfonso , Dellabona Paolo , Casorati Giulia , Chambers Benedict J. , Kiessling Rolf , Bejarano Maria-Teresa , Ljunggren Hans-Gustaf 
Published: December 2022

AbstractNK cell-mediated effector functions are regulated by a delicate balance between positive and negative signals. Receptors transmitting negative signals upon engagement with target cell MHC class I molecules have been characterized in detail in recent years. In contrast, less information is available about receptor-ligand interactions involved in the transmission of positive or “triggering” signals to NK cells. Recently, it has been described that murine NK cells are triggered by the costimulatory molecules CD80, CD86, and CD40. Using NK cell lines derived from PBMC as effectors, we demonstrate that the human CD80 and CD86 gene products can function as triggering molecules for NK cell-mediated cytotoxicity. Expression of human CD80 or CD86 molecules in murine B16.F1 melanoma cells rendered these significantly more susceptible to lysis by human NK cell lines. Blocking of the transfected gene products with specific mAb reduced lysis levels to that of nontransfected control cell lines. Triggering of human NK cells by CD80 and CD86 appeared to be independent of CD28 and CTLA-4, at least as determined by the reagents used in the present study, because the expression of these molecules could not be detected on the NK cell lines by either flow cytometry or in redirected lysis assays. Thus, human NK cells may use receptors other than CD28 and CTLA-4 in their interactions with CD80 and CD86 molecules. Alternatively, interactions may involve variants of CD28 (and possibly CTLA-4) that are not recognized by certain anti-CD28 mAb.
CD2 and CD3 Associate Independently with CD5 and Differentially Regulate Signaling Through CD5 in Jurkat T Cells
Authors: Carmo Alexandre M. , Castro Mónica A. A. , Arosa Fernando A. 
Published: December 2022

AbstractIn T lymphocytes, the CD2 and CD5 glycoproteins are believed to be involved in the regulation of signals elicited by the TCR/CD3 complex. Here we show that CD2 and CD3 independently associate with CD5 in human PBMC and Jurkat cells. CD5 coprecipitates with CD2 in CD3-deficient cells and, conversely, coprecipitates with CD3 in cells devoid of CD2. In unstimulated CD2+ CD3+ Jurkat cells, CD5 associates equivalently with CD2 and CD3 and is as efficiently phosphorylated in CD2 as in CD3 immune complexes. However, upon activation the involvement of CD5 is the opposite in the CD2 and CD3 pathways. CD5 becomes rapidly tyrosine phosphorylated after CD3 stimulation, but is dephosphorylated upon CD2 cross-linking. These opposing effects correlate with the decrease in the activity of the SH2 domain-containing protein phosphatase 1 (SHP-1) following CD3 activation vs an enhanced activity of the phosphatase after CD2 triggering. The failure of CD5 to become phosphorylated on tyrosine residues in the CD2 pathway has no parallel with the lack of use of ζ-chains in CD2 signaling; contrasting with comparable levels of association of CD2 or CD3 with CD5, ζ associates with CD2 only residually and is nevertheless slightly phosphorylated after CD2 stimulation. The modulation of CD5 phosphorylation may thus represent a level of regulation controlled by CD2 in signal transduction mechanisms in human T lymphocytes.
Contrasting the In Situ Behavior of a Memory B Cell Clone During Primary and Secondary Immune Responses
Authors: Vora Kalpit A. , Tumas-Brundage Kathleen , Manser Tim 
Published: December 2022

AbstractWhether memory B cells possess altered differentiative potentials and respond in a qualitatively distinct fashion to extrinsic signals as compared with their naive precursors is a current subject of debate. We have investigated this issue by examining the participation of a predominant anti-arsonate clonotype in the primary and secondary responses in the spleens of A/J mice. While this clonotype gives rise to few Ab-forming cells (AFC) in the primary response, shortly after secondary immunization its memory cell progeny produce a massive splenic IgG AFC response, largely in the red pulp. Extensive clonal expansion and migration take place during the secondary AFC response but Ab V region somatic hypermutation is not reinduced. The primary and secondary germinal center (GC) responses of this clonotype are both characterized by ongoing V gene hypermutation and phenotypic selection, little or no inter-GC migration, and derivation of multiple, spatially distinct GCs from a single progenitor. However, the kinetics of these responses differ, with V genes containing a high frequency of total as well as affinity-enhancing mutations appearing rapidly in secondary GCs, suggesting either recruitment of memory cells into this response, or accelerated rates of hypermutation and selection. In contrast, the frequency of mutation observed per V gene does not increase monotonically during the primary GC response of this clonotype, suggesting ongoing emigration of B cells that have sustained affinity- and specificity-enhancing mutations.
An Extensive Region of an MHC Class I α2 Domain Loop Influences Interaction with the Assembly Complex
Authors: Yu Yik Y. L. , Turnquist H¯eth R. , Myers Nancy B. , Balendiran Ganesaratnam K. , Hansen Ted H. , Solheim Joyce C. 
Published: December 2022

AbstractPresentation of antigenic peptides to CTLs at the cell surface first requires assembly of MHC class I with peptide and β2-microglobulin in the endoplasmic reticulum. This process involves an assembly complex of several proteins, including TAP, tapasin, and calreticulin, all of which associate specifically with the β2-microglobulin-assembled, open form of the class I heavy chain. To better comprehend at a molecular level the regulation of class I assembly, we have assessed the influence of multiple individual amino acid substitutions in the MHC class I α2 domain on interaction with TAP, tapasin, and calreticulin. In this report, we present evidence indicating that many residues surrounding position 134 in H-2Ld influence interaction with assembly complex components. Most mutations decreased association, but one (LdK131D) strongly increased it. The Ld mutants, with the exception of LdK131D, exhibited characteristics suggesting suboptimal intracellular peptide loading, similar to the phenotype of Ld expressed in a tapasin-deficient cell line. Notably, K131D was less peptide inducible than wild-type Ld, which is consistent with its unusually strong association with the endoplasmic reticulum assembly complex.
Protective Immunity Using Recombinant Human IL-12 and Alum as Adjuvants in a Primate Model of Cutaneous Leishmaniasis
Authors: Kenney Richard T. , Sacks David L. , Sypek Joseph P. , Vilela Luciano , Gam Albert A. , Evans-Davis Kamela 
Published: December 2022

Abstract
Protection from cutaneous leishmaniasis, a chronic ulcerating skin lesion affecting millions, has been achieved historically using live virulent preparations of the parasite. Killed or recombinant Ags that could be safer as vaccines generally require an adjuvant for induction of a strong Th1 response in murine models. Murine rIL-12 as an adjuvant with soluble Leishmania Ag has been shown to protect susceptible mice. We used 48 rhesus macaques to assess the safety, immunogenicity, and efficacy of a vaccine combining heat-killed Leishmania amazonensis with human rIL-12 (rhIL-12) and alum (aluminum hydroxide gel) as adjuvants. The single s.c. vaccination was found to be safe and immunogenic, although a small transient s.c. nodule developed at the site. Groups receiving rhIL-12 had an augmented in vitro Ag-specific IFN-γ response after vaccination, as well as increased production of IgG. No increase in IL-4 or IL-10 was found in cell culture supernatants from either control or experimental groups. Delayed hypersensitivity reactions were not predictive of protection. Intradermal forehead challenge infection with 107 metacyclic L. amazonensis promastigotes at 4 wk demonstrated protective immunity in all 12 monkeys receiving 2 μg rhIL-12 with alum and Ag. Partial efficacy was seen with lower doses of rhIL-12 and in groups lacking either adjuvant. Thus, a single dose vaccine with killed Ag using rhIL-12 and alum as adjuvants was safe and fully effective in this primate model of cutaneous leishmaniasis. This study extends the murine data to primates, and provides a basis for further human trials.
IL-15 Prolongs the Duration of CD8+ T Cell-Mediated Immunity in Mice Infected with a Vaccine Strain ofToxoplasma gondii
Authors: Khan Imtiaz A. , Casciotti Lori 
Published: December 2022

AbstractImmunization of mice with a vaccine (ts-4) strain of Toxoplasma gondii is known to induce complete protection against subsequent lethal infection. Ts-4-mediated protection has been reported to be primarily dependent on IFN-γ-producing CD8+ T cells. However, duration of CD8+ T cell-mediated immunity in the ts-4-vaccinated animals is not known. In the present study, the kinetics of the CD8+ T cell response in mice immunized with the ts-4 strain of T. gondii was evaluated. Optimal CD8+ T cell immunity persisted at least 6 mo after vaccination, and mice at this time point continued to overcome lethal challenge with a more virulent strain. However, at 9 mo postimmunization, CD8+ T cell immunity was severely diminished and the mice succumbed to Toxoplasma challenge. Pretreatment of animals, vaccinated 9 mo earlier, with rIL-15 prevented the mortality induced by Toxoplasma challenge. The protective effect of IL-15 treatment was due to a rise in the frequency of Ag-specific CD8+ T cells. CD8+ T cells from IL-15-administered animals showed increased proliferation and IFN-γ production in response to antigenic restimulation. These findings suggest that rIL-15 can reverse the decline in the long-term CD8+ T cell immune response in mice immunized with vaccine strain of T. gondii.
Protein Kinase C (PKC) Isoforms Translocate to Triton-Insoluble Fractions in Stimulated Human Neutrophils: Correlation of Conventional PKC with Activation of NADPH Oxidase
Authors: Nixon Jennifer B. , McPhail Linda C. 
Published: December 2022

Abstract
The responses of human neutrophils (PMN) involve reorganization and phosphorylation of cytoskeletal components. We investigated the translocation of protein kinase C (PKC) isoforms to PMN cytoskeletal (Triton-insoluble) fractions, in conjunction with activation of the respiratory burst enzyme NADPH oxidase. In resting PMN, PKC-δ (29%) and small amounts of PKC-α (0.6%), but not PKC-βII, were present in cytoskeletal fractions. Upon stimulation with the PKC agonist PMA, the levels of PKC-α, PKC-βII, and PKC-δ increased in the cytoskeletal fraction, concomitant with a decrease in the noncytoskeletal (Triton-soluble) fractions. PKC-δ maximally associated with cytoskeletal fractions at 160 nM PMA and then declined, while PKC-α and PKC-βII plateaued at 300 nM PMA. Translocation of PKC-δ was maximal by 2 min and sustained for at least 10 min. Translocation of PKC-α and PKC-βII was biphasic, plateauing at 2–3 min and then increasing up to 10 min. Under maximal stimulation conditions, PKC isoforms were entirely cytoskeletal associated. Translocation of the NADPH oxidase component p47phox to the cytoskeletal fraction correlated with translocation of PKC-α and PKC-βII, but not with translocation of PKC-δ. Oxidase activity in cytoskeletal fractions paralleled translocation of PKC-α, PKC-βII, and p47phox. Stimulation with 1,2-dioctanoylglycerol resulted in little translocation of PKC isoforms or p47phox, and in minimal oxidase activity. We conclude that conventional PKC isoforms (PKC-α and/or PKC-βII) may regulate PMA-stimulated cytoskeletal association and activation of NADPH oxidase. PKC-δ may modulate other PMN responses that involve cytoskeletal components.
CC Chemokine Receptor 5 Cell-Surface Expression in Relation to CC Chemokine Receptor 5 Genotype and the Clinical Course of HIV-1 Infection
Authors: de Roda Husman Ana-Maria , Blaak Hetty , Brouwer Margreet , Schuitemaker Hanneke 
Published: December 2022

AbstractCCR5 cell-surface expression was studied in relation to CCR5 genotype and clinical course of HIV-1 infection. HIV-1 infected CCR5+/+ individuals had higher percentages of CCR5-expressing CD4+ T cells as compared with HIV-1-infected CCR532/+ individuals. For both genotypic groups, the percentages of CCR5-expressing cells were higher than for the uninfected counterparts (CCR5+/+, HIV+ 28% and HIV− 15% (p &lt; 0.0001); CCR532/+, HIV+ 21% and HIV− 10% (p = 0.001), respectively). In HIV-1-infected individuals, high percentages of CCR5-expressing cells were associated with low CD4+ T cell numbers (p = 0.001), high viral RNA load in serum (p = 0.046), and low T cell function (p = 0.054). As compared with nonprogressors with similar CD4+ T cell numbers, individuals who did progress to AIDS had a higher percentage of CCR5-expressing CD4+ T cells (32% vs 21% (p = 0.002). Longitudinal analysis of CCR5+/+ individuals revealed slight, although not statistically significant, increases in CCR5-expressing CD4+ T cells and CD4+ T cell subsets characterized by the expression of CD45 isoforms, during the course of HIV-1 infection. Preseroconversion, the percentage of CCR5-expressing CD4+ T cells was higher in individuals who subsequently developed AIDS (28%) than in those who did not show disease progression within a similar time frame (20%; p = 0.059). Our data indicate that CCR5 expression increases with progression of disease, possibly as a consequence of continuous immune activation associated with HIV-1 infection. In turn, CCR5 expression may influence the clinical course of infection.
Isolation, Characterization and Sequence Analysis of Five IgG Monoclonal Anti-β2-Glycoprotein-1 and Anti-Prothrombin Antigen-Binding Fragments Generated by Phage Display
Authors: Chukwuocha Reginald U. , Hsiao Elie T. , Shaw Peter , Witztum Joseph L. , Chen Pojen P. 
Published: December 2022

AbstractWe have isolated five monoclonal IgG anti-β2-glycoprotein-1 (anti-β2G-1) and anti-prothrombin Fab from a patient with autoantibodies to oxidized low-density lipoproteins by phage display method. Analysis of their binding specificity revealed that all three β2GP-1-enriched mAbs (B14, B22, B27) reacted with β2GP-1 while both prothrombin-isolated mAbs (P11 and P13) reacted with prothrombin. Intriguingly, mAb P11 reacted with β2GP-1 and prothrombin and showed comparable binding affinity to both Ags, with Kd values of 1.6 × 10−6 M for β2GP-1 vs 3.2 × 10−6 M for prothrombin. This clone may thus, define a hitherto unknown shared epitope between β2GP-1 and prothrombin. Sequence analysis of all five clones showed significant mutations of the expressed genes. One rearranged V-D-J segment was repeatedly employed by three clones (mAbs B22, B27, and P13). However, all three clones used different L chains. Of note, the pairing of VH6-D-J with the L5-Vk1 L chain in mAb P13 resulted in the loss of binding to β2GP-1 and specific reactivity to prothrombin. Together, these data suggest that while the VH6-D-J chain may be important in the binding to β2GP-1, pairing with certain L chains may influence this binding. These data are the first human IgG anti-β2GP-1 and anti-prothrombin sequences reported; both represent the major subsets of antiphospholipid Abs present in antiphospholipid syndrome patients.
C1q-Containing Immune Complexes Purified from Sera of Juvenile Rheumatoid Arthritis Patients Mediate IL-8 Production by Human Synoviocytes: Role of C1q Receptors
Authors: Khalkhali-Ellis Zhila , Bulla Gary A. , Schlesinger Larry S. , Kirschmann Dawn A. , Moore Terry L. , Hendrix Mary J. C. 
Published: December 2022

AbstractImmune complexes that vary in size and composition are present in the sera and synovial fluid of juvenile rheumatoid arthritis (JRA) patients. They are believed to be potent inducers of the ongoing inflammatory process in JRA. However, the precise composition and role of these complexes in the pathophysiology of JRA remain unclear. We hypothesized that circulating ICs have the potential to interact with resident joint synovial fibroblasts (synoviocytes) and induce the expression of inflammatory cytokines. To test this hypothesis, cultures of synoviocytes from healthy individuals were treated with ICs isolated from the sera of JRA patients. Studies reported in this work demonstrate that IgM affinity-purified ICs from the sera of JRA patients contain IgM, C1q, IgG, and C3 to a variable extent. These ICs induce IL-8 mRNA and protein production in normal synoviocytes. Our data indicate that C1q in these ICs mediates, in part, IL-8 induction in synoviocytes. This is based on our findings of C1q-binding proteins for collagen stalks (cC1qR) and globular heads (gC1q-binding protein) of C1q in synoviocytes. In addition, collagen stalk and to some extent globular head fragments of C1q inhibit IC-mediated IL-8 induction in synoviocytes. Together, these findings provide evidence for a novel mechanism of IL-8 production by synoviocytes, which could play a key role in inflammation by recruiting leukocytes to synovial tissue and fluid—and subsequently contributing to joint disease.
Cutting Edge: Role of C-C Chemokine Receptor 5 in Organ-Specific and Innate Immunity toCryptococcus neoformans
Authors: Huffnagle Gary B. , McNeil Lisa K. , McDonald Roderick A. , Murphy Juneann W. , Toews Galen B. , Maeda Nobuyo , Kuziel William A. 
Published: December 2022

AbstractAfter intratracheal inoculation of the AIDS-associated pathogen Cryptococcus neoformans, 12-wk survival was &gt;90% for CCR5+/+ mice but &lt;25% for CCR5−/− mice. There were no defects in lung leukocyte recruitment (wk 5), pulmonary clearance, or delayed-type hypersensitivity in CCR5−/− mice. However, CCR5−/− mice had defects in leukocyte recruitment into the brain and, strikingly, in elimination of cryptococcal polysaccharide from the brain. In nonimmune CCR5−/− mice, there was a significant defect in macrophage recruitment after challenge with shed cryptococcal products (C. neoformans filtrate Ag) but not other nonspecific stimuli. Thus, CCR5 plays specific roles in innate immunity and organ-specific leukocyte trafficking during host defense against C. neoformans.
Antigen Presentation Determines the Fate of the T Memory Response In Vivo After Sublethal Gamma-Irradiation
Authors: Sechler Joan M. G. , Hansal Susan A. , Morris Diane I. , McFarland Hugh I. , Rosenberg Amy S. 
Published: December 2022

AbstractThe survival of memory T cells is critical to vaccination strategies for infectious diseases and cancer, whereas their elimination may be crucial for treatment of autoimmune states. We examined the consequences of gamma-irradiation, which induces apoptosis of memory T cells in vitro, on the memory response to MHC class I alloantigen in vivo. Sublethal gamma-irradiation of primed mice eliminated accelerated rejection of skin allografts but failed to induce tolerance. Accelerated rejection was restored in irradiated mice by infusion of bone marrow cells expressing the priming alloantigen on immunostimulatory APCs (dendritic cells), whereas the memory response was not restored by infusion of bone marrow cells expressing the priming alloantigen on nonstimulatory APCs (B cells). Strikingly, irradiated mice infused with nonstimulatory bone marrow APCs exhibited long-term survival or tolerance to skin grafts expressing the priming MHC class I alloantigen. The mechanism of tolerance in this setting is explored.
Age-Associated Rapid and Stat6-Independent IL-4 Production by NK1−CD4+8− Thymus T Lymphocytes
Authors: Chen Yi-Ting , Chen Fen-Ling , Kung John T. 
Published: December 2022

AbstractThe source of IL-4 required for priming naive T cells into IL-4-secreting effectors has not been clearly identified. Here we show that upon TCR stimulation, thymus NK1−CD4+8− T cells produced IL-4, the magnitude of which was inversely correlated with age. This IL-4 production response by Th2-prone BALB/c mice was ∼9-fold that of Th1-prone C57BL/10 mice. More than 90% of activated NK1−CD4+8− thymocytes did not use the invariant Vα14-Jα281 chain characteristic of typical CD1-restricted NK1+CD4+ T cells. Stat6-null NK1−CD4+8− thymocytes produced bioactive IL-4, with induction of IL-4 mRNA expression within 1 h of stimulation. Our results support the possibility that TCR repertoire-diverse conventional NK1−CD4+ T cells are a potential IL-4 source for directing naive T cells toward Th2/type 2 CD8+ T cell (Tc2) effector development.