bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tissue-Specific Recognition of Mouse CD1 Molecules
Authors: Park Se-Ho , Roark Jessica H. , Bendelac Albert 
Published: December 2022

AbstractAlthough there is evidence that some members of the CD1 gene family may present particular types of foreign Ags, such as mycobacterial lipid Ags or synthetic hydrophobic peptides, to αβ T cells, most CD1 isotypes share the unusual property of being recognized by a high frequency of naturally autoreactive αβ T cells. In the case of mouse CD1.1 and its human counterpart CD1d, a significant fraction of the autoreactive T cells express semi-invariant TCRs. CD1.1-specific T cells have a restricted tissue distribution and very promptly secrete a large panel of potent cytokines, including IL-4 and IFN-γ, upon primary activation through their TCR, suggesting that they might regulate some immune responses in these tissues. We show here that their autorecognition of mouse CD1.1 is highly dependent upon the cell type in which CD1.1 is expressed. For example, some of these T cells only respond to CD1.1 expressed by splenic dendritic cells, some respond preferentially to cortical thymocytes, and others respond to splenic B cells. Tissue specificity of CD1.1 recognition is also observed with various cell lines transfected with CD1.1 cDNA. These results show that different CD1.1 self Ags are expressed in different tissues and can be specifically recognized by autoreactive T cells. They suggest that CD1.1 may be naturally associated with a variety of self ligands that overlap only partially in different cell types.
Overexpression of the p80 TNF Receptor Leads to TNF-Dependent Apoptosis, Nuclear Factor-κB Activation, and c-Jun Kinase Activation
Authors: Haridas Valsala , Darnay Bryant G. , Natarajan K. , Heller Renu , Aggarwal Bharat B. 
Published: December 2022

Abstract
Because they have distinct intracellular domains, it has been proposed that the p60 and p80 forms of the TNF receptor mediate different signals. Several signaling proteins have been isolated that associate with either the p60 or the p80 receptor. By using TNF muteins specific to the p60 and p80 receptors, we have previously shown that cytotoxicity and nuclear factor-κB (NF-κB) activation are mediated through the p60 form of the endogenous receptor. What signals are mediated through the p80 receptor is less clear. This study was an effort to answer that question. HeLa cells, which express only p60 receptors, were transfected with p80 receptor cDNA and then examined for apoptosis, NF-κB activation, and c-Jun kinase activation induced by TNF and by p60 or p80 receptor-specific muteins. The p80 mutein, like TNF and the p60 mutein, induced apoptosis and activation of NF-κB and c-Jun kinase in cells overexpressing recombinant p80 receptor but had no effect on cells expressing a high level of endogenous p80 receptor. The apoptosis mediated through the p60 receptor was also potentiated after overexpression of the p80 receptor, suggesting a synergistic relationship between the two receptors. Interestingly, Abs to the p80 receptor blocked apoptosis induced by all ligands but by itself activated NF-κB in the p80-transfected cells. Overall, our results show that the p80 receptor, which lacks the death domain, mediated apoptosis, NF-κB activation, and c-Jun kinase activation, but only when it was overexpressed, whereas endogenous p60 receptor mediated similar signals without overexpression.
In Vivo β-Adrenergic Stimulation Suppresses Natural Killer Activity and Compromises Resistance to Tumor Metastasis in Rats
Authors: Shakhar Guy , Ben-Eliyahu Shamgar 
Published: December 2022

AbstractThe sympathetic nervous system has been implicated in mediating stress-induced alterations in NK cell activity, particularly through stimulation of β-adrenergic receptors. However, because catecholamines induce time-dependent alterations in the distribution of NK cells, the impact of β-adrenergic stimulation on individual NK cell cytotoxicity is not clear, nor are its implications regarding host resistance to metastatic spread. To address these issues, we used the β-adrenergic agonist, metaproterenol (MP), in F344 rats. The number of blood NK cells doubled within 10 min of MP administration and returned to baseline levels within 1 h. By this time, MP suppressed blood NK activity in a dose-dependent manner. Two β-adrenergic antagonists, propranolol, which crosses the blood-brain barrier, and nadolol, which does not, blocked this suppression. Corresponding findings were obtained using an NK-sensitive tumor model, the MADB106. MP caused an up to 10 times increase in the number of tumor cells retained in the lungs 1 day after inoculation and a similar rise in the number of consequent lung metastases detected 3 wk later. These effects were dose dependent and nadolol reversible. NK cells appear to play a central role in mediating the tumor-enhancing effects of MP because their selective depletion nearly abolished this effect. Overall, our findings suggest that independent of the transitory increase in numbers of blood NK cells, in vivo β-adrenergic stimulation suppresses NK activity in the rat. This suppression is induced peripherally and can compromise host resistance to NK-sensitive tumors. Homologies to studies in humans and clinical relevance are discussed.
Asymmetrical Phosphorylation and Function of Immunoreceptor Tyrosine-Based Activation Motif Tyrosines in B Cell Antigen Receptor Signal Transduction
Authors: Pao Lily I. , Famiglietti Sara J. , Cambier John C. 
Published: December 2022

AbstractCD79a and CD79b function as transducers of B cell antigen receptor signals via a cytoplasmic sequence, termed the immunoreceptor tyrosine-based activation motif (ITAM). ITAMs contain two conserved tyrosines that may become phosphorylated upon receptor aggregation and bind distinct effectors by virtue of the distinct preference of phosphotyrosyl-containing sequences for SH2 domains. To explore the function of CD79a and CD79b ITAM tyrosines, we created membrane molecules composed of MHC class II I-Ak extracellular and transmembrane domains, and CD79a or CD79b cytoplasmic domains in which one or both of the ITAM tyrosines were mutated to phenylalanine. Functional analysis revealed that both ITAM tyrosines are required for ligand-induced Syk phosphorylation. However CD79a-ITAM and CD79b-ITAM tyrosine phosphorylations were asymmetrical, with &gt;80% of phosphorylation occurring on the N-terminal tyrosine (Y-E-G-L). Thus, these findings suggest that following receptor ligation, only a minor proportion of phosphorylated ITAMs are doubly phosphorylated and thus can engage Syk. Only the N-terminal ITAM tyrosine of CD79a was required for ligand-mediated phosphorylation of the receptor and a subset of downstream substrates, including p62, p110, and Shc, and for Ca2+ mobilization. However, responses mediated through CD79b exhibited a greater dependence on the presence of both tyrosines. Neither tyrosine in CD79a or CD79b appeared absolutely essential for Src family kinase phosphorylation. These results indicate that phosphorylations of the tyrosines in CD79a and CD79b occur with very different stoichiometry, and the respective tyrosyl residues have distinct functions.
Stimulation of Murine B Lymphocytes Induces a DNA Exonuclease Whose Activity on Switch-μ DNA Is Specifically Inhibited by Other Germ-Line Switch Region RNAs
Authors: Müller Jürgen R. , Marcu Kenneth B. 
Published: December 2022

AbstractThe Ig heavy chain class switch in B lymphocytes involves a unique genetic recombination that fuses specific regions within the Ig locus and deletes intervening sequences. Here we describe a novel exonuclease activity in nuclear lysates of B cells in an in vitro assay. This activity was induced in B lymphocytes after treatment with either LPSs or CD40 ligand/anti-δ-dextran, both of which induce switch recombination, and considerably less activity was detected in untreated or anti-δ-dextran-treated B cells, Con A-stimulated spleen cells, liver cells, or a number of cell lines. The exonuclease activity was dependent on divalent cations, and both 3′ and 5′ labels were efficiently removed from DNA substrates. The presence of RNase A, but not RNase H, inhibited exonucleolytic digestion, suggesting that a ribonucleoprotein is responsible for the exonucleolysis. The DNA digestion appears to be nonspecific, since DNA substrates with either switch-μ or unrelated sequence were hydrolyzed with comparable efficiency. Germ-line switch region transcripts (Igγ1, Igγ3, and Igα) strongly inhibited the exonucleolysis of switch-μ DNA but not that of unrelated control DNA, while switch antisense RNA or tRNA were much less effective inhibitors.
Identification of a Domain in Human Factor H and Factor H-Like Protein-1 Required for the Interaction with Streptococcal M Proteins
Authors: Kotarsky Heike , Hellwage Jens , Johnsson Eskil , Skerka Christine , Svensson Henrik G. , Lindahl Gunnar , Sjöbring Ulf , Zipfel Peter F. 
Published: December 2022

AbstractThe plasma protein factor H (FH) inhibits the alternative pathway of complement activation. Previous work has shown that FH binds to group A streptococci and that the interaction does not interfere with the complement-inhibitory capacity of FH. In this work, we report a molecular analysis of this interaction. In absorption experiments with human plasma, M protein-expressing group A streptococci bound both FH and FH-like protein-1 (FHL-1), an active 42-kDa splice product of the FH-gene transcript comprising the first 7 of its 20 short consensus repeat (SCR) domains. rFHL-1 also bound to M protein-expressing streptococci, but rFH fragments containing SCR 1–5 or SCR 1–6 did not. rFHL-1 bound to purified M5 protein with an affinity that was higher than the value calculated for the interaction between FH and M5 protein. The binding of radiolabeled rFHL-1 to immobilized M5 was blocked completely by unlabeled rFHL-1, but was inhibited only partially by SCR 1–6, emphasizing the importance of SCR 7 for the interaction. In experiments with the FH-related proteins FHR-3 and FHR-4, only the former bound to M protein-expressing streptococci, again pointing to an involvement of SCR 7, since FHR-3, but not FHR-4, contains a domain that is similar to SCR 7. Finally, the interaction between rFHL-1 and purified M5 protein was inhibited by heparin, which binds FH via SCR 7. Together, these data indicate that the interaction between streptococcal M proteins and FH or FHL-1 requires SCR 7.
Purification of L-Selectinlow Cells Promotes the Generation of Highly Potent CD4 Antitumor Effector T Lymphocytes
Authors: Kagamu Hiroshi , Shu Suyu 
Published: December 2022

AbstractSuccessful adoptive immunotherapy of cancer requires the identification, isolation, and expansion of tumor-specific immune effector cells. A reliable source of tumor-immune lymphocytes is lymph nodes draining a growing tumor. After in vitro stimulation with anti-CD3 and expansion in IL-2, these cells are capable of mediating the regression of established tumors. In the absence of further Ag stimulation, we recently found that the down-regulation of the homing molecule L-selectin could serve as a surrogate marker for isolation of specific tumor-sensitized T cells. The L-selectinlow (L-selectin−) T cells proliferated more vigorously than unfractionated or L-selectinhigh cells. In adoptive immunotherapy of established intracranial MCA 205 tumors, L-selectin− cells displayed at least 30-fold greater therapeutic efficacy than unfractionated cells. L-selectinhigh cells did not demonstrate any antitumor effects. Activated L-selectin− cells secreted a number of cytokines, including IFN-γ, IL-2, IL-4, and IL-10, specifically when stimulated with cognate tumor cells. Further analysis revealed that CD4 T cells alone mediated tumor regression and secreted cytokines. Our results thus demonstrate that the purification of L-selectin− cells led to the generation of CD4 immune effector cells with unusually high therapeutic efficacy against chemically induced tumors. The lack of cytotoxicity and the ability to secrete cytokines suggest that these effector CD4 cells mediate antitumor effects through an indirect mechanism similar to the delayed hypersensitivity reaction.
Regulation of Cell Growth by IL-2: Role of STAT5 in Protection from Apoptosis But Not in Cell Cycle Progression
Authors: Zamorano José , Wang Helen Y. , Wang Rouxiang , Shi Yufang , Longmore Gregory D. , Keegan Achsah D. 
Published: December 2022

AbstractCytokines play an essential role in the regulation of lymphocyte survival and growth. We have analyzed the pathways activated by IL-2 that lead to protection from apoptosis and cell proliferation. IL-2 can act as a long-term growth factor in 32D cells expressing the wild-type human (hu)IL-2Rβ. By contrast, cells expressing a truncated form of the huIL-2Rβ, which is able to induce Bcl-2 and c-myc expression but not STAT5 activation, were not protected from apoptosis by IL-2; consequently, they could not be grown long term in the presence of IL-2. However, IL-2 promoted cell cycle progression in cells bearing the truncated huIL-2Rβ with percentages of viable cells in the G0/G1, S, and G2/M phases similar to cells expressing the wild-type huIL-2Rβ. Transplantation of a region from the erythropoietin receptor, which contains a docking site for STAT5 (Y343) to the truncated huIL-2Rβ, restored the ability of IL-2 to signal both activation of STAT5 and protection from apoptosis. By contrast, transplantation of a region from the huIL-4Rα containing STAT6 docking sites did not confer protection from apoptosis. These results indicate that the IL-2-induced cell cycle progression can be clearly distinguished from protection from apoptosis and that STAT5 participates in the regulation of apoptosis.
IL-17 Stimulates the Production and Expression of Proinflammatory Cytokines, IL-β and TNF-α, by Human Macrophages
Authors: Jovanovic Dragan V. , Di Battista John A. , Martel-Pelletier Johanne , Jolicoeur François C. , He Yulan , Zhang Mengkun , Mineau François , Pelletier Jean-Pierre 
Published: December 2022

AbstractIL-17 is a newly described, T cell-derived cytokine with ill-defined physiologic properties. As such, we examined the release of proinflammatory mediators by human macrophages in response to recombinant human (rh) IL-17. IL-1β and TNF-α expression and synthesis were up-regulated by rhIL-17 in a dose (ED50 was 50 ± 9 ng/ml)- and time-dependent fashion, with cytokine accumulation reaching a zenith after 9 h. Release of IL-6, PGE2, IL-10, IL-12, IL-1R antagonist, and stromelysin was also stimulated by rhIL-17. IL-1β and TNF-α mRNA expression levels were controlled by rhIL-17 in a complex manner with an initial 30-min inhibitory phase, and then up-regulation beginning at 1 h and reaching a plateau at about 3 h. The latter expression pattern closely mirrored the nuclear accumulation of the transcription factor nuclear factor-κB. cAMP mimetics isobutyl-1-methylxanthine (IBMX), forskolin, PGE2, and cholera toxin reversed rhIL-17-induced release of TNF-α, but had no consistent effect on induced IL-1β synthesis. Induced release of TNF-α was also inhibited by serine/threonine protein kinase inhibitors KT-5720 (protein kinase A) and Calphostin C (protein kinase C), mitogen-activated protein kinase kinase inhibitor PD098059, and a nonspecific tyrosine kinase inhibitor, genistein. Calphostin C alone abrogated the rhIL-17-induced release of IL-1β. The antiinflammatory cytokines IL-4 (p &lt; 0.01) and IL-10 (p &lt; 0.02) completely reversed rhIL-17-stimulated IL-1β release, while IL-13 and TGF-β2 were partially effective (59 and 43% diminution, respectively). IL-10 exerted a significant suppressive effect on IL-17-induced TNF-α release (99%, p &lt; 0.02), while the inhibitory effects of IL-4, IL-13, and TGF-β2 on TNF-α secretion were partial (48, 10, and 23%, respectively). The data suggest a pivotal role for IL-17 in initiating and/or sustaining an inflammatory response.
Involvement of NK1+ T Cells and Their IFN-γ Production in the Generalized Shwartzman Reaction
Authors: Ogasawara Kouetsu , Takeda Kazuyoshi , Hashimoto Wataru , Satoh Masayuki , Okuyama Ryuhei , Yanai Nobuaki , Obinata Masuo , Kumagai Katsuo , Takada Haruhiko , Hiraide Hoshio , Seki Shuhji 
Published: December 2022

AbstractIL-12 (or LPS) priming and subsequent challenge by LPS produces the generalized Shwartzman reaction. IFN-γ induced by IL-12 is a crucial cytokine in the priming phase. In vivo depletion of both NK cells and NK1+ αβ T cells of mice by anti-NK1.1 Ab greatly reduced the elevation of serum IFN-γ induced by IL-12 and significantly reduced mortality after subsequent injection of LPS, whereas depletion of NK cells alone by anti-asialo GM1 Ab only partially decreased serum IFN-γ, and lethality was not changed. Cell sorting and culture experiments confirmed that liver NK1+ αβ T cells of IL-12-injected mice produced greater amounts of IFN-γ than did liver NK cells. MHC class I-deficient mice of C57BL/6 background, which lack a majority of NK1+ αβ T cells, produced low amounts of IFN-γ by IL-12; no mortality was observed after the LPS challenge. However, production of TNF-α in the second phase (after LPS challenge) was not inhibited by depletion of NK cells alone or both subsets. IL-12 and subsequent LPS challenge activated NK1+ αβ T cells in the liver and induced strong cytotoxicity of these cells not only against tumor cells (including Fas-negative tumors) but also against a syngeneic hepatocyte cell line. Our findings show that IFN-γ produced by NK1+ αβ T cells is essential for the IL-12 priming of the Shwartzman reaction, and the autoreactivity of NK1+ αβ T cells in the liver is involved in the hepatic disorders that are sometimes caused by IL-12, LPS, or the generalized Shwartzman reaction.
IgE Versus IgG4 Production Can Be Differentially Regulated by IL-10
Authors: Jeannin Pascale , Lecoanet Sybille , Delneste Yves , Gauchat Jean-François , Bonnefoy Jean-Yves 
Published: December 2022

AbstractAllergen-specific IgE plays a key role in the physiopathology of allergic disorders. This IgE response is usually accompanied by a production of IgG4. Indirect evidence suggests that IgG4 may not be a sensitizing Ab but, in contrast, could be protective. As such, it may be of potential therapeutic interest to selectively modulate IgE vs IgG4 production. To date, IgE and IgG4 switching seems to be controlled by common mechanisms. We report here that IL-10 has a differential effect on IgE vs IgG4 production by PBMC. IL-10 decreases ε transcript expression and IgE production induced by IL-4 when added during the first 3 days of in vitro culture, suggesting that IL-10 decreases IL-4-induced IgE switching. In contrast, if added later on B cells that are already IgE switched, IL-10 potentiates IgE production. Interestingly, whatever the time of addition, IL-10 augments IL-4-induced γ4 transcript expression and IgG4 production, with a maximal effect when added during the first 3 days. As IL-10 is not a switch factor for IgG4, it is likely that IL-10 enhances IgG4 production by potentiating IL-4-induced IgG4 switching. However, IL-10 may also act by enhancing the growth and/or differentiation of cells that are already IgG4 committed. Finally, CD40 ligation reverses the early down-regulating effect of IL-10 on IgE production. These results are the first evidence of a molecule that differentially regulates IgE vs IgG4 production, thereby suggesting the existence of a pathway(s) selectively controlling their production.
Dendritic Cells and Macrophages Are the First and Major Producers of TNF-α in Pancreatic Islets in the Nonobese Diabetic Mouse
Authors: Dahlén Eva , Dawe Kim , Ohlsson Lennart , Hedlund Gunnar 
Published: December 2022

AbstractThe nonobese diabetic (NOD) mouse spontaneously develops autoimmune insulin-dependent diabetes mellitus (IDDM) and serves as an animal model for human type I diabetes. TNF-α is known to be produced by islet-infiltrating mononuclear cells during insulitis and subsequent β cell destruction and has been implicated in the pathogenesis of IDDM. Previously, T cells have been suggested as the main source of TNF-α in the islet infiltrate. However, on immunohistochemical analysis of TNF-α expression in islets, we are able to show that the staining pattern of TNF-α resembles that of dendritic cells (DC) and macrophages (Mφ) rather than T cells and that TNF-α is expressed in islets at the very early stages of insulitis when no T cells are detected. On double staining for TNF-α and cell surface markers, we can demonstrate that TNF-α staining clearly correlates with DC and Mφ, whereas there is a poor correlation with T cells. This feature was observed at both early and late stages of insulitis. TNF-α expression was also seen in NOD-SCID islets, in addition to a peri-islet infiltration consisting of DC and Mφ, indicating that T cells are not required for the early DC and Mφ infiltration and TNF-α expression in islets. In conclusion, our results show that DC and Mφ are the major, early source of TNF-α in the NOD islet infiltrate and that TNF-α can be expressed independently of T cells, indicating that the early DC and Mφ infiltration and expression of TNF-α are crucial in initiation of diabetes.
Specific Suppression of Human CD4+ Th Cell Responses to Pig MHC Antigens by CD8+CD28− Regulatory T Cells
Authors: Ciubotariu Rodica , Colovai Adriana I. , Pennesi Giuseppina , Liu Zhouru , Smith Douglas , Berlocco Pasquale , Cortesini Raffaello , Suciu-Foca Nicole 
Published: December 2022

AbstractEvidence that T cells can down-regulate the immune response by producing or consuming certain cytokines or by lysing APCs or Th cells has been provided in various systems. However, the generation and characterization of suppressor T cell lines have met with limited success. Here we show that xenospecific suppressor T cells can be generated by in vitro stimulation of human T cells with pig APCs. Similar to allospecific suppressors, these xenospecific suppressor T cells carry the CD8+CD28− phenotype and react to MHC class I Ags expressed by the APCs used for priming. TCR spectratyping of T suppressor cells showed oligoclonal usage of TCR-Vβ families, indicating that xenostimulation of CD8+CD28− T cells results in Ag-driven selection of a limited Vβ repertoire. Xenospecific T suppressor cells prevent the up-regulation of CD154 molecules on the membrane of Th cells, inhibiting their ability to react against the immunizing MHC class II xenoantigens. The mechanism of this suppression, therefore, appears to be blockade of CD154/CD40 interaction required for efficient costimulation of activated T cells.