bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cutting Edge: Apoptosis of Superantigen-Activated T Cells Occurs Preferentially After a Discrete Number of Cell Divisions In Vivo
Authors: Renno Toufic , Attinger Antoine , Locatelli Sabrina , Bakker Talitha , Vacheron Sonia , MacDonald H. Robson 
Published: January 2023

Abstract
Staphylococcal enterotoxins are bacterial products that display superantigen activity in vitro as well as in vivo. For instance, staphylococcal enterotoxin B (SEB) polyclonally activates T cells that bear the Vβ8 gene segment of the TCR. SEB-activated T cells undergo a burst of proliferation that is followed by apoptosis. Using an in vivo adaptation of a fluorescent cell division monitoring technique, we show here that SEB-activated T cells divide asynchronously, and that apoptosis of superantigen-activated T cells is preferentially restricted to cells which have undergone a discrete number of cell divisions. Collectively, our data suggest that superantigen-activated T cells are programmed to undergo a fixed number of cell divisions before undergoing apoptosis. A delayed death program may provide a mechanistic compromise between effector functions and homeostasis of activated T cells.
Inhibition of B Cell Receptor-Mediated Apoptosis by IFN
Authors: Su Leon , David Michael 
Published: January 2023

AbstractIFNs are a family of cytokines that are involved in the regulation of immune and inflammatory responses. Clinical use of IFN-α/β encompasses treatment for a variety of diseases; however, prolonged exposure to IFN-α/β results in elevated levels of autoreactive Abs. In this study, we investigated the potential of IFNs to modulate apoptotic signals in B cells. We demonstrate that IFN-α or IFN-β inhibit Ag receptor-mediated apoptosis in a dose-dependent manner. Inhibition of phosphatidylinositol 3′ (PI3)-kinase did not abolish the effect of IFN, indicating that the antiapoptotic mechanism is PI3-kinase- and protein kinase B/Akt-independent. Instead, IFN-α and IFN-β, but not IFN-γ, significantly increase the levels of the survival protein Bcl-2, and to a lesser extent, Bcl-xL expression. Thus, IFN-α/β-mediated inhibition of B cell Ag receptor-triggered apoptosis may offer a model for the process that leads to the escape of self-reactive B cells from negative selection and consequently results in autoantibody production.
Cross-Linking of Membrane CD43 Mediates Dendritic Cell Maturation
Authors: Corinti Silvia , Fanales-Belasio Emanuele , Albanesi Cristina , Cavani Andrea , Angelisova Pavla , Girolomoni Giampiero 
Published: January 2023

Abstract
CD43/leukosialin is a major sialoglycoprotein of the dendritic cell (DC) surface, which can regulate cell adhesion and has the potential to mediate cell activation signals. Monocyte-derived DC transiently incubated with the anti-CD43 mAb, MEM-59, or with F(ab′)2 fragments, but not with monovalent Fab fragments or control IgG, 24 h later showed increased levels of membrane HLA-DR, CD54, CD40, CD80, CD86, and CD83. In parallel, CD43 cross-linking induced synthesis and release of IL-1β, IL-6, TNF-α, IL-12, and IL-10. CD43 ligation inhibited the endocytic activity of DC, and enhanced the capacity of DC to stimulate T cell proliferation in the primary allogeneic and autologous MLR assay. In addition, anti-CD43-treated DC were less efficient at presenting native HIV-1 reverse transcriptase to a specific CD4+ T cell clone, whereas presentation of the reverse transcriptase 55–72 peptide to the same clone was increased. Finally, MEM-59 or its F(ab′)2 fragments elicited a rise in intracellular free calcium and tyrosine phosphorylation of a 25-kDa protein in DC. The results thus indicate that CD43 cross-linking with specific ligands induces activation and functional maturation of DC.
Maturation of Dendritic Cells Accompanies High-Efficiency Gene Transfer by a CD40-Targeted Adenoviral Vector
Authors: Tillman Bryan W. , Gruijl Tanja D. de , Bakker Sylvia A. Luykx-de , Scheper Rik J. , Pinedo Herbert M. , Curiel Tyler J. , Gerritsen Winald R. , Curiel David T. 
Published: January 2023

Abstract
Important therapeutic applications of genetically modified dendritic cells (DC) have been proposed; however, current vector systems have demonstrated only limited gene delivery efficacy to this cell type. By means of bispecific Abs, we have dramatically enhanced gene transfer to monocyte derived DC (MDDC) by retargeting adenoviral (Ad) vectors to a marker expressed on DC, CD40. Adenovirus targeted to CD40 demonstrated dramatic improvements in gene transfer relative to untargeted Ad vectors. Fundamental to the novelty of this system is the capacity of the vector itself to modulate the immunological status of the MDDC. This vector induces DC maturation as demonstrated phenotypically by increased expression of CD83, MHC, and costimulatory molecules, as well as functionally by production of IL-12 and an enhanced allostimulatory capacity in a MLR. In comparing this vector to other Ad-based gene transfer systems, we have illustrated that the features of DC maturation are not a function of the Ad particle, but rather a consequence of targeting to the CD40 marker. This vector approach may thus mediate not only high-efficiency gene delivery but also serve a proactive role in DC activation that could ultimately strengthen the utility of this vector for immunotherapy strategies.
Induction of T Cell Anergy by Low Numbers of Agonist Ligands
Authors: Korb Laura C. , Mirshahidi Saied , Ramyar Kasra , Sadighi Akha Amir A. , Sadegh-Nasseri Scheherazade 
Published: January 2023

Abstract
Engagement of TCR by its ligand, the MHC/peptide complex, causes T cell activation. T cells respond positively to stimulation with agonists, and are inhibited by antagonist MHC/peptide ligands. Failure to induce proper conformational changes in the TCR or fast TCR/MHC dissociation are the leading models proposed to explain anergy induction by antagonist ligands. In this study, we demonstrate that presentation of between 1 and 10 complexes of agonist/MHC II by unfixed APC induces T cell anergy that persists up to 7 days and has characteristics similar to anergy induced by antagonist ligand or TCR occupancy without costimulation. Furthermore, anergy-inducing doses of hemagglutinin 306–318 peptide led to the engagement of less than 1000 TCR/CD3 complexes. Thus, engagement of a subthreshold number of TCR by either a low density of agonist/MHC or a 2–3 orders of magnitude higher density of antagonist/MHC causes anergy. Moreover, we show that anergy induced by low agonist concentrations is inhibited in the presence of IL-2 or cyclosporin A, suggesting involvement of the calcineurin signaling pathway.
A Critical Role for Antigen-Specific Th1 Cells in Acute Liver Injury in Mice
Authors: Nishimura Takashi , Ohta Akio 
Published: January 2023

Abstract
A novel liver injury model was established in mice by targeting of OVA-containing liposomes into the liver, followed by adoptive transfer of OVA-specific Th1 cells. Combined treatment of mice with OVA-containing liposomes and Th1 cell transfer caused an increase in serum transaminase activity that was paralleled with an elevation of serum IFN-γ levels. In sharp contrast, OVA-specific Th2 cell transfer resulted in an increase of serum IL-4 levels, but did not induce liver injury. Neither NK, NK T, nor CD8+ T cells were required for the Th1-induced liver injury. The liver injury was blocked by anti-IFN-γ mAb and anti-TNF-α mAb, but not by anti-Fas ligand mAb. The Fas/Fas ligand independency was also demonstrated using Fas-deficient lpr mice. These findings indicate that Th1 cells are the major effector cells in acute liver injury.
Early Arrest in B Cell Development in Transgenic Mice That Express the E41K Bruton’s Tyrosine Kinase Mutant Under the Control of the CD19 Promoter Region
Authors: Maas Alex , Dingjan Gemma M. , Grosveld Frank , Hendriks Rudolf W. 
Published: January 2023

Abstract
Bruton’s tyrosine kinase (Btk) is a nonreceptor protein kinase that is defective in X-linked agammaglobulinemia in humans and in X-linked immunodeficiency in mice. To study the effect of Btk activation in early B cell development in vivo, we have created transgenic mouse strains expressing Btk under the control of the human CD19 promoter region. The transgenic expression of wild-type human Btk corrected all X-linked immunodeficiency features in mice carrying a targeted disruption of the Btk gene. In contrast, expression of an activated form of Btk, the E41K mutant, resulted in an almost complete arrest of B cell development in the immature IgM+IgD− B cell stage in the bone marrow, irrespective of the presence of the endogenous intact Btk gene. Immature B cells were arrested at the progression from IgMlow into IgMhigh cells, which reflects the first immune tolerance checkpoint at which autoreactive B cells become susceptible to apoptosis. As the constitutive activation of Btk is likely to mimic B cell receptor occupancy by autoantigens in the bone marrow, our findings are consistent with a role for Btk as a mediator of B cell receptor-induced apoptotic signals in the immature B cell stage. Whereas the peripheral mature B cell pool was reduced to &lt;1% of the normal size, significant numbers of IgM-secreting plasma cells were present in the spleen. Serum IgM levels were substantial and increased with age, but specific Ab responses in vivo were lacking. We conclude that the residual peripheral B cells were efficiently driven into IgM+ plasma cell differentiation, apparently without functional selection.
Perforin Is a Major Contributor to NK Cell Control of Tumor Metastasis
Authors: Smyth Mark J. , Thia Kevin Y. T. , Cretney Erika , Kelly Janice M. , Snook Marie B. , Forbes Catherine A. , Scalzo Anthony A. 
Published: January 2023

Abstract
We provide the first demonstration, using experimental and spontaneous models of metastasis in C57BL/6 (B6) (RM-1 prostate carcinoma) and BALB/c (DA3 mammary carcinoma) mice, that tumor metastasis is primarily controlled by perforin-dependent cytotoxicity mediated by NK1.1+ cells. MHC class Ilow RM-1 and DA3 tumor cells were sensitive in vitro to Fas-mediated lysis or spleen NK cells in a perforin-dependent fashion. Perforin-deficient NK cells did not lyse these tumors, and perforin-deficient mice were 10–100-fold less proficient than wild-type mice in rejecting the metastasis of tumor cells to the lung. Fas ligand mutant gld mice displayed uncompromised protection against tumor metastasis. Depletion of NK subsets resulted in greater numbers of metastases than observed in perforin-deficient mice, suggesting that perforin-independent effector functions of NK cells may also contribute to protection from tumor metastasis.
Negative Regulation by Protein Tyrosine Phosphatase of IFN-γ-Dependent Expression of Inducible Nitric Oxide Synthase
Authors: Díaz-Guerra María J. M. , Castrillo Antonio , Martín-Sanz Paloma , Boscá Lisardo 
Published: January 2023

Abstract
Treatment of cultured peritoneal macrophages with IFN-γ resulted in tyrosine phosphorylation of IκBα and IκBβ, NF-κB activation, and expression of inducible NO synthase (iNOS). Since tyrosine phosphorylation of IκBα is sufficient to activate NF-κB in Jurkat cells, macrophages were treated with the protein tyrosine phosphatase inhibitor peroxovanadate (POV), which elicited an intense tyrosine phosphorylation of both IκB. However, this phosphorylation failed to activate NF-κB. Treatment with POV of macrophages stimulated with IFN-γ or LPS potentiated the degradation of IκBα and IκBβ, the activation of NF-κB, and the expression of iNOS. Analysis of the iNOS gene promoter activity corresponding to the 5′-flanking region indicated that POV potentiates the cooperation between IFN-γ-activated transcription factors and NF-κB. These results indicate that tyrosine phosphorylation of IκB is not sufficient to activate NF-κB in macrophages and propose a negative role for protein tyrosine phosphatase in the expression of iNOS in response to IFN-γ.
Macrophage Recognition of ICAM-3 on Apoptotic Leukocytes
Authors: Moffatt Odette D. , Devitt Andrew , Bell Elaine D. , Simmons David L. , Gregory Christopher D. 
Published: January 2023

Abstract
Cells undergoing apoptosis are cleared rapidly by phagocytes, thus preventing tissue damage caused by loss of plasma membrane integrity. In this study, we show that the surface of leukocytes is altered during apoptosis such that the first Ig-like domain of ICAM-3 (CD50) can participate in the recognition and phagocytosis of the apoptotic cells by macrophages. Macrophage recognition of apoptotic cell-associated ICAM-3 was demonstrated both on leukocytes and, following transfection of exogenous ICAM-3, on nonleukocytes. The change in ICAM-3 was a consistent consequence of apoptosis triggered by various stimuli, suggesting that it occurs as part of a final common pathway of apoptosis. Alteration of ICAM-3 on apoptotic cells permitting recognition by macrophages resulted in a switch in ICAM-3-binding preference from the prototypic ICAM-3 counterreceptor, LFA-1, to an alternative macrophage receptor. Using mAbs to block macrophage/apoptotic cell interactions, we were unable to obtain evidence that either the alternative ICAM-3 counterreceptor αdβ2 or the apoptotic cell receptor αvβ3 was involved in the recognition of ICAM-3. By contrast, mAb blockade of macrophage CD14 inhibited ICAM-3-dependent recognition of apoptotic cells. These results show that ICAM-3 can function as a phagocytic marker of apoptotic leukocytes on which it acquires altered macrophage receptor-binding activity.
Direct Delivery of the Bordetella pertussis Adenylate Cyclase Toxin to the MHC Class I Antigen Presentation Pathway
Authors: Guermonprez Pierre , Ladant Daniel , Karimova Gouzel , Ullmann Agnes , Leclerc Claude 
Published: January 2023

Abstract
Among bacterial toxins, the adenylate cyclase toxin of Bordetella pertussis (CyaA) has a unique mechanism of entry that consists in the direct translocation of its catalytic domain across the plasma membrane of target cell, a mechanism supposed to be independent of any endocytic pathway. Here, we report that the CyaA toxin is delivered to the cytosolic pathway for MHC class I-restricted Ag presentation. Using peritoneal macrophages as APC, we show that the OVA 257–264 CD8+ epitope genetically inserted into a detoxified CyaA (CyaA-OVA E5) is presented to CD8+ T cells by a mechanism requiring 1) proteasome processing, 2) TAP, and 3) neosynthesis of MHC class I. We demonstrate that the presentation of CyaA-OVA E5, like the translocation of CyaA into eukaryotic cells, is dependent on extracellular Ca2+ and independent of vacuolar acidification. Moreover, inhibitors of the phagocytic and macropinocytic endocytic pathways do not affect the CyaA-OVA E5 presentation. The absence of specific cellular receptors for CyaA correlates with the ability of various APC to present the recombinant CyaA toxin, including dendritic cells, macrophages, splenocytes, and lymphoid tumoral lines. Taken together, our results show that the CyaA presentation pathway is not cell type specific and is unrelated to a defined type of endocytic mechanism. Thus, it represents a new and unconventional delivery of an exogenous Ag into the conventional cytosolic pathway.
Dual MHC Class I and Class II Restriction of a Single T Cell Receptor: Distinct Modes of Tolerance Induction by Two Classes of Autoantigens
Authors: Arsov Ivica , Vukmanović Stanislav 
Published: January 2023

AbstractIn the final stages of thymic development, immature T cells undergo three distinct processes (positive selection, negative selection, and lineage commitment) that all depend on interactions of thymocyte TCRs with MHC molecules. It is currently thought that TCRs are preferentially restricted by either MHC class I or class II molecules. In this report, we present direct evidence that the TCR previously described as H-Y/H-2Db specific cross-reacts with H-2IAb if expressed in CD4+ cells. We also demonstrate an increase in thymocyte numbers in H-Y TCR-trangenic mice deficient in MHC class II, suggesting a relatively discrete form of negative selection by MHC class II compared with that induced by H-Y/H-2Db. We propose that inability to generate CD4+ T cells expressing H-Y TCR in different experimental settings may be due to tolerance to self-MHC class II. These results, therefore, support an intriguing possibility that tolerance to self may influence and/or interfere with the outcome of the lineage commitment.
Specific CD3ε Association of a Phosphodiesterase 4B Isoform Determines Its Selective Tyrosine Phosphorylation After CD3 Ligation
Authors: Baroja Miren L. , Cieslinski Lenora B. , Torphy Theodore J. , Wange Ronald L. , Madrenas Joaquín 
Published: January 2023

Abstract
cAMP-specific phosphodiesterases (PDE) comprise an extensive family of enzymes that control intracellular levels of cAMP and thus regulate T cell responses. It is not known how the function of these enzymes is altered by TCR engagement. We have examined this issue by studying one of the PDE isozymes (PDE4B). PDE4B RNA and protein were detected in resting PBLs, and the levels of PDE4B protein increased with cell cycling. In peripheral blood T cells, two previously reported PDE4B isoforms could be detected: one was 75–80 kDa (PDE4B1) and the other was 65–67 kDa (PDE4B2). These two isoforms differed in their N-terminal sequence, with the presence of four potential myristylation sites in the PDE4B2 that are absent in PDE4B1. Consequently, only PDE4B2 was found in association with the CD3ε chain of the TCR. In addition, although both isoforms were phosphorylated in tyrosines in pervanadate-stimulated T cells, only the TCR-associated PDE4B2 was tyrosine-phosphorylated following CD3 ligation. The kinetics of phosphorylation of TCR-associated PDE4B2 correlated with changes in cAMP levels, suggesting that tyrosine phosphorylation of the TCR-associated PDE4B isoform upon engagement of this receptor may be an important regulatory step in PDE4B function. Our results reveal that selectivity of PDE4B activation can be achieved by differential receptor association and phosphorylation of the alternatively spliced forms of this PDE.
Increased TNF-α-Induced Apoptosis in Lymphocytes from Aged Humans: Changes in TNF-α Receptor Expression and Activation of Caspases
Authors: Aggarwal Sudeepta , Gollapudi Sastry , Gupta Sudhir 
Published: January 2023

Abstract
Aging is characterized by increased T cell lymphopenia, T cell dysfunction, and increased serum TNF levels. In this study, we have examined the role of TNF-induced apoptosis in T cell deficiency in lymphocytes from aged humans. The constitutive expression of TNF receptors (TNFRI and TNFRII) and the adapter molecules, including TNFR-associated death domain protein (TRADD), TNFR-associated factor 2 (TRAF-2), and receptor interacting protein (RIP), were analyzed both at the protein level by flow cytometry or Western blotting, and at the mRNA level using quantitative PCR or Northern blotting in lymphocytes from aged and young subjects. The susceptibility of T cells to undergo TNF-induced apoptosis was analyzed using terminal deoxynucleotidyltransferase-mediated UTP-end-labeling (TUNEL) and DNA ladder assays. Caspase (caspase-8 and caspase-3) activation was compared between aged and young subjects using Western blotting and colorimetric assays. In lymphocytes from aged humans, there was an increased susceptibility of CD4+ and CD8+ T cells to undergo TNF-α-induced apoptosis, as observed by TUNEL assay and DNA fragmentation ladder assay. Increased TNF-α-induced apoptosis was also observed in both CD45RA+ and CD45RO+ T cells from aging subjects. An increased constitutive expression of TNFRI and TRADD and decreased expression of TNFRII and TRAF-2 were observed in lymphocytes from aged as compared with young controls. In addition, there was an early and increased activation of caspases (caspase-8 and caspase-3) involved in TNFR/TNF signaling pathway, as evident by early cleavage of caspase-8, poly(ADP-ribose) polymerase (PARP), and caspase-3 substrate DEVD-p-nitroamilide NA. These data suggest that an increased TNF-α-induced apoptosis may play a role in T cell deficiency associated with human aging.
Signal Transduction Pathways Involved in the Activation of NF-κB, AP-1, and c-fosbyMycoplasma fermentansMembrane Lipoproteins in Macrophages
Authors: Rawadi Georges , Garcia Josefina , Lemercier Brigitte , Roman-Roman Sergio 
Published: January 2023

AbstractMycoplasma fermentans-derived membrane lipoproteins (LAMPf) have been demonstrated to stimulate monocytic cells and to induce the secretion of proinflammatory cytokines by a mechanism involving the triggering of protein tyrosine kinase and mitogen-activated protein kinase cascades. Herein, we have examined the effects of LAMPf on the activation of a series of transcription factors potentially involved in cytokine gene expression. LAMPf was capable to induce NF-κB, activated protein 1 (AP-1), and c-fos activation in macrophages and to stimulate NF-κB and AP-1 transactivation. Furthermore, we have delineated the contribution of each mitogen-activated protein kinase pathway to the LAMPf-mediated activation of AP-1, c-fos, and NF-κB. Whereas the selective extracellular signal-regulated kinase pathway inhibitor PD-98059 did not affect the LAMPf-mediated transactivation of AP-1, c-fos, or NF-κB, the specific p38 inhibitor SB203580 abrogated this activity. A c-Jun N-terminal kinase-dominant negative was shown to block the activation of AP-1 without altering NF-κB or c-fos activation by LAMPf. In addition, D609, a selective inhibitor of phosphatidylcholine-specific phospholipase C, was shown to block both translocation and transactivation of either NF-κB or AP-1 in response to LAMPf. Although LAMPf-mediated macrophage activation is CD14 independent, we could not distinguish between the intracellular mechanisms leading to the macrophage activation triggered by either LPS or LAMPf. This suggests that macrophages display a common signaling machinery leading to the secretion of proinflammatory cytokines in response to different bacterial products. The comprehension of these mechanisms may help to better understanding the bacterial pathogenesis and to elucidate general mechanisms of macrophage activation leading to cytokine secretion.
Isolation of High Avidity Melanoma-Reactive CTL from Heterogeneous Populations Using Peptide-MHC Tetramers
Authors: Yee Cassian , Savage Peter A. , Lee Peter P. , Davis Mark M. , Greenberg Philip D. 
Published: January 2023

AbstractImmunogenic peptides of human tumor Ag have been used to generate antigen-specific CTL. However, the vast majority of these peptide-specific CTL clones are of low avidity and are peptide, but not tumor, reactive. Peptide-MHC tetramers have been shown to bind specific TCRs with sufficient affinity to be useful reagents for flow cytometry. In this paper we demonstrate that peptide-MHC tetramers can also be used to selectively identify high avidity tumor-reactive CTL and enrich, from a heterogeneous population, the subpopulation of peptide-reactive T cells that can lyse tumor targets. The melanoma proteins, MART-1 and gp100, were used to induce potentially tumor-reactive T cells, and the intensity of T cell staining by TCR binding of specific peptide-MHC tetramers was assessed. A range of fluorescence intensity was detected, and the magnitude of tetramer binding was correlated with T cell avidity. The population of peptide-reactive T cells was phenotypically similar with regard to expression of TCR and adhesion molecules, suggesting that this differential avidity for tumor cells reflected differential affinity of the TCR for its peptide-MHC ligand. Sorting, cloning, and expansion of tetramerhigh CTL from a heterogeneous population of peptide-stimulated PBMCs enabled rapid selection of high avidity tumor-reactive CTL clones, which retained their functional and tetramerhigh phenotype on re-expansion. These results demonstrate that the avidity of a T cell for its tumor target is due to the specific affinity of the TCR for its peptide-MHC ligand, that this interaction can be described using peptide-MHC tetramers and used to isolate high avidity tumor-reactive CTL.