bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression of Two Different Antiphagocytic M Proteins byStreptococcus pyogenesof the OF+ Lineage
Authors: Thern Anette , Wästfelt Maria , Lindahl Gunnar 
Published: January 2023

AbstractAll clinical isolates of Streptococcus pyogenes (group A streptococcus) share the ability to resist phagocytosis and grow in human blood. In many strains, this property is due to the expression of a single antiphagocytic M protein, while other strains express more than one M-like molecule, of which the role in phagocytosis resistance is unclear. In particular, all S. pyogenes strains of the OF+ lineage, representing approximately half of all isolates, express two M-like proteins, Mrp and Emm, which are immunologically unrelated. These two proteins bind different ligands that have been implicated in phagocytosis resistance: Mrp binds fibrinogen and Emm binds the complement inhibitor C4BP. Using a clinical isolate of the common serotype 22, we created mutants affected in the mrp and emm genes and characterized them in phagocytosis experiments and by electron microscopy. A double mutant mrp−emm− showed strongly decreased resistance to phagocytosis, while mrp− and emm− single mutants grew well in blood. However, optimal growth required the expression of both Mrp and Emm. Experiments in which coagulation was inhibited using the specific thrombin inhibitor, hirudin, rather than heparin, indicated that Emm is more important than Mrp for resistance to phagocytosis. Tuftlike surface structures typical for S. pyogenes were still present in the mrp−emm− double mutant, but not in a mutant affected in the regulatory gene mga, indicating that the presence of these surface structures is not directly correlated to phagocytosis resistance. Our data imply that OF+ strains of S. pyogenes express two antiphagocytic M proteins with different ligand-binding properties.
Cutting Edge: CD40 Ligand Is Not Essential for the Development of Cell-Mediated Immunity and Resistance toMycobacterium tuberculosis
Authors: Campos-Neto Antonio , Ovendale Pamela , Bement Teresa , Koppi Thelma A. , Fanslow William C. , Rossi Marcos A. , Alderson Mark R. 
Published: January 2023

AbstractIt has been proposed that the induction of cellular immunity and resistance to intracellular pathogens is dependent upon CD40 ligand (CD40L). In the present study we show that this proposal is not ubiquitously supported. Mice genetically deficient in CD40L (CD40LKO) were resistant to i.v. infection with Mycobacterium tuberculosis when assessed by survival and bacteriologic burden in the spleen, liver, and lungs. Infected CD40LKO mice developed granulomas that lacked epithelioid cells and were less numerous and markedly smaller than those observed in control mice. Upon stimulation with purified protein derivative of M. tuberculosis,CD4+ T cells from infected CD40LKO mice proliferated and produced high levels of IFN-γ but not IL-4. Finally, spleen cells from CD40LKO mice stimulated with M. tuberculosis produced IL-12, TNF, and nitric oxide levels comparable to those produced by control cells. In contrast to original proposals, these data clearly show that protective Th1 immunity can be achieved against intracellular pathogens (e.g., Mycobacterium) independently of CD40L.
Differential Presentation of the Same MHC Class I Epitopes by Fibroblasts and Dendritic Cells
Authors: Butz Eric A. , Bevan Michael J. 
Published: January 2023

AbstractAg is presented to CTL as peptide associated with MHC class I molecules, which are present on most types of cells. We have investigated the presentation of Db-restricted lymphocytic choriomeningitis virus (LCMV) peptides by a fibroblast line (MC57) and a dendritic cell line (JawsII) to splenocytes from LCMV-immune C57BL/6 mice. We found that when LCMV-infected MC57 were used to restimulate the spleen cells, the resulting CTL line lost its ability to respond to the two dominant epitopes of the immune response to LCMV glycoprotein (gp)33 and nucleoprotein (np)396 but remained strongly lytic for targets coated with the subdominant gp276 epitope. In contrast, when LCMV-infected JawsII cells were used to restimulate the splenocytes, the resulting line continued to target gp33 and np396 but lost reactivity to gp276. When uninfected JawsII or MC57 cells were coated with peptides and used as stimulators, the resulting CTL lines continued to recognize all three epitopes, indicating that costimulatory or other potential innate differences in Ag presentation between the two cell lines are unlikely to account for the selective expansion of CTL specificities. When infected, both cell types produce similar levels of infectious LCMV, have similar levels of the NP and GP proteins from which np396 and gp33 are derived, and can be recognized by CTL specific for each of the three epitopes. These data indicate that in the generation of peptides for MHC-I binding and presentation to CTL, MC57 and JawsII process the same set of virus proteins in quantitatively different ways.
Mutation of Proline 211 Reduces Shedding of the Human p75 TNF Receptor
Authors: Herman Charlotte , Chernajovsky Yuti 
Published: January 2023

Abstract
We have identified a residue necessary for the cleavage of human p75 TNF-R from the cell surface by deletion and mutagenesis analysis of the membrane-proximal domain between amino acids 147 and 221. Deletion analysis of this area showed that residues between amino acids 207 and 216 are required for shedding. Site-directed mutagenesis of proline 211 to glycine reduced PMA-induced shedding of human p75 TNF-R from COS-7 or Raw 264.7 cells. Mutation of glycine 210 to aspartic acid did not affect receptor shedding. Mutation of serine 212 to leucine did not affect the PMA-induced shedding from the surface of COS-7 cells, but reduced the efficiency of shedding from the surface of Raw 264.7 macrophages by PMA or LPS. Deletion of putative elastase cleavage sites at amino acids 151 to 153, 162 to 163, and 177 to 178 (also a putative metalloprotease site similar to the cleavage site of TNF-α) or mutation of a serine-threonine-serine motif resembling a similar motif at the site of L-selectin cleavage at amino acids 202 to 204 did not reduce shedding of p75 TNF-R after treatment of cells with PMA. This work shows that a single amino acid mutation at proline 211 of human p75 TNF-R can prevent shedding from the cell surface, and that deletion of other previously proposed putative cleavage sites of the human p75 TNF-R does not prevent its shedding.
Mouse CD1-Autoreactive T Cells Have Diverse Patterns of Reactivity to CD1+ Targets
Authors: Brossay Laurent , Tangri Shabnam , Bix Mark , Cardell Susanna , Locksley Richard , Kronenberg Mitchell 
Published: January 2023

AbstractHumans and mice contain significant populations of T cells that are reactive for autologous CD1 molecules. Using a panel of five mouse CD1 (mCD1)-autoreactive T cell hybridomas, we show here that this autoreactivity does not correlate with the level of CD1 expression. In some cases, these autoreactive T cells can distinguish between different cell types that express the same CD1 molecule, suggesting that some factor in addition to CD1 expression is critical for autoreactive T cell stimulation. To determine whether a CD1-bound ligand may be required, we expressed mutant mCD1 molecules that are defective for the putative endosomal localization sequence in the cytoplasmic domain. We demonstrate that mCD1, like its human CD1 homologues, is found in endosomes, and that it colocalizes extensively with the DM molecule. We further demonstrate, by site-directed mutagenesis, that the tyrosine in the cytoplasmic sequence is required for this endosomal localization. A T cell hybrid expressing Vβ8 and Vα14, the major TCR expressed by NK1+ T cells, exhibited greatly diminished reactivity to mutant CD1 molecules that do not traffic through endosomes, although the reactivity of other T cell hybrids to this mutant was not greatly affected. Therefore, we propose that at least some of the autoreactive T cells require endosomally derived CD1-bound ligands, and that they are capable of distinguishing between a diverse set of such self-ligands, which might be either autologous lipoglycans or peptides.
Induction of a Th1 Immune Response and Simultaneous Lack of Activation of a Th2 Response Are Required for Generation of Immunity to Leishmaniasis
Authors: Sjölander Anders , Baldwin Tracey M. , Curtis Joan M. , Handman Emanuela 
Published: January 2023

Abstract
Experimental systems based on immunization with plasmid DNA or immune-stimulating complexes were used to delineate the requirements for generation of protective immunity against murine leishmaniasis. Vaccination with plasmid DNA encoding the host-protective Leishmania major parasite surface Ag-2 primed for an essentially exclusive Th1 response that protected mice against L. major infection. In contrast, parasite surface Ag-2 in immune-stimulating complexes generated an immune response with mixed Th1-like and Th2-like properties that was not protective despite the activation of large numbers of CD4+ T cells secreting IFN-γ. These results indicate that a Th1 response is sufficient to protect against cutaneous leishmaniasis, but the induction of a simultaneous Th2 response abrogates the Th1 effector function. DNA vaccines may therefore have an advantage for diseases in which protection depends on the induction of Th1 responses.
Immunopathology of Herpetic Stromal Keratitis: Discordance in CD4+ T Cell Function Between Euthymic Host and Reconstituted SCID Recipients
Authors: Thomas Johnson , Rouse Barry T. 
Published: January 2023

Abstract
Infection of the mouse cornea with herpes simplex virus (HSV) results in an immunopathologic disease of the eye termed herpetic stromal keratitis (HSK), in which the principal orchestrator is the CD4+ T cell. The mouse genotype largely determines susceptibility or resistance to HSK. BALB/c mice (H2dIgh-1a) are susceptible, while its congenic C.B-17 strain (H2dIgh-1b), which differs only in the Ig heavy chain locus, is resistant to HSK. As the magnitude and duration of viral replication as well as anti-HSV immune responses were similar in both strains, it was determined whether resistance was due to failure of CD4+ T cells to organize the immunopathologic reaction. Adoptive transfer of HSV-primed or naive CD4+ T cells from resistant C.B-17 strain into HSV-infected SCID mice resulted in HSK lesions indistinguishable from those caused by similar transfers of BALB/c CD4+ T cells. Similar results were obtained with transfers of whole T cell populations as well as with unfractionated splenocytes from the resistant mice. These results show that while intact C.B-17 mice exhibit resistance to HSK, they possess potentially pathogenic CD4+ T cells in their repertoire. The data suggest that the HSV-infected SCID mouse provides a proinflammatory microenvironment that overrides regulatory controls and/or cause activation of quiescent cells into aggressive effector T cells that orchestrate HSK.
Hydrogen Peroxide Induces Up-Regulation of Fas in Human Endothelial Cells
Authors: Suhara Toshimitsu , Fukuo Keisuke , Sugimoto Tomosada , Morimoto Shigeto , Nakahashi Takeshi , Hata Shigeki , Shimizu Masumi , Ogihara Toshio 
Published: January 2023

Abstract
Hydrogen peroxide (H2O2), an oxidant generated by inflammatory cells, is an important mediator of injury of endothelial cells (ECs). Here we show that H2O2 induces up-regulation of the expression of Fas, a death signal, in human ECs in culture. Flow cytometric analysis with a mAb against human Fas showed that incubation for 24 h with H2O2 induced a dose-dependent increase in the level of Fas in ECs. Coincubation with catalase, which rapidly degrades H2O2, inhibited H2O2-induced up-regulation of Fas. H2O2 also induced a dose-dependent increase in Fas mRNA level. A significant increase in Fas mRNA levels was observed from 6 h after stimulation with H2O2. Vanadate, a protein phosphatase inhibitor, significantly enhanced Fas mRNA and protein levels in H2O2-treated ECs. On the other hand, genistein, a tyrosine kinase inhibitor, inhibited H2O2-induced Fas mRNA expression. Furthermore, a flow cytometric method with propidium iodide staining and electron microscopic analysis showed that incubation with an agonistic Ab against Fas (anti-Fas IgM) induced apoptosis in H2O2-treated cells. These findings suggest that H2O2 induces up-regulation of Fas in ECs and that activation of protein tyrosine kinase may be involved in the mechanism of H2O2-induced Fas expression. Therefore, Fas-mediated apoptosis may have a pathologic role in H2O2-induced EC injury and thereby provide a new therapeutic target.
Differential Requirements for LFA-1 Binding to ICAM-1 and LFA-1-Mediated Cell Aggregation
Authors: Petruzzelli Lilli , Maduzia Lisa , Springer Timothy A. 
Published: January 2023

AbstractCellular adhesion through the β2 integrin lymphocyte function-associated Ag (LFA)-1 is a complex event involving activation, ligand binding, and cell shape changes that ultimately result in enhanced adhesion. In this report we define requirements for ligand binding and post receptor signaling by comparing two mechanisms of activation of LFA-1: 1) inside-out signaling and 2) direct activation by the β2 Ab, CBR LFA-1/2. Our results demonstrate that activation of LFA-1 binding to ICAM-1 by CBR LFA-1/2, in contrast to inside-out signaling mechanisms, does not require protein kinase C activation or protein phosphatase 2A activity nor is it affected by agents that interfere with reorganization of the cytoskeleton. Inhibition of protein tyrosine kinase activity does not affect ICAM-1 binding by either mechanism of activation. However, activation by either mode does require the presence of the β cytoplasmic domain; deletion of the C-terminal phenylalanine or the five amino acid stretch between 756–762 abolished activation of LFA-1. This, combined with the observation that intracellular energy pools must be preserved, implicates the β cytoplasmic domain in a key energy-dependent conformational change in LFA-1 that is required to achieve enhanced ligand binding. Post ligand binding events induced by both PMA and Ab stimulation, as measured by homotypic aggregation, require protein tyrosine kinase, phosphatase, and RhoA activities. By examining both ligand binding and aggregation, we have been able to dissect the signaling components critical in the multistep process of LFA-1-mediated cellular adhesion.
Involvement of CD40 Ligand-CD40 and CTLA4-B7 Pathways in Murine Acute Graft-Versus-Host Disease Induced by Allogeneic T Cells Lacking CD28
Authors: Saito Kiyoshi , Sakurai Jinkyo , Ohata Junko , Kohsaka Takao , Hashimoto Hiroshi , Okumura Ko , Abe Ryo , Azuma Miyuki 
Published: January 2023

AbstractThe blockade of B7, using B7 antagonists such as anti-CD80 and/or -CD86 mAbs or CTLA4Ig in vivo, has been shown to induce an efficient suppression of T cell-mediated immune responses in allograft, allergy, and autoimmune models. However, this treatment does not result in complete tolerance. In this study, we examined CD28-B7-independent activation pathways in the pathogenesis of graft-vs-host disease (GVHD) using allogeneic T cells from CD28-deficient mice. Acute GVHD was induced in the absence of CD28 on donor T cells and its manifestations were obvious in the lymphoid tissues. The CD28-independent GVHD was significantly improved by treatment with anti-CD40 ligand (CD40L) mAb. In contrast, treatment with anti-CD80 plus anti-CD86 mAbs exacerbated the clinical manifestations of GVHD and increased the T cell response against host alloantigen, resulting in the expression of CTLA4, CD40L, and CD25 on splenic T cells. These data suggested that the CD40L-CD40 pathway significantly contributed to the CD28-independent pathogenesis of acute GVHD, whereas the CTLA4-B7 pathway acted protectively in the development of GVHD. These results imply that selectively blockading CD28, instead of disrupting both CD28 and CTLA4, would be a better therapeutic strategy for GVHD. Additionally, the simultaneous use of CD40 antagonists may be advantageous.
Promiscuous Binding of Synthetic Copolymer 1 to Purified HLA-DR Molecules
Authors: Fridkis-Hareli Masha , Strominger Jack L. 
Published: January 2023

AbstractCopolymer 1 (Cop 1) is a random synthetic amino acid copolymer of l-alanine, l-glutamic acid, l-lysine, and l-tyrosine, effective both in suppression of experimental allergic encephalomyelitis and in the treatment of relapsing forms of multiple sclerosis. Cop 1 binds promiscuously and very efficiently to living APCs of various HLA haplotypes. In the present study, a substantial part of the whole mixture of random polypeptides that compose Cop 1 was shown to bind to purified human HLA-DR1, DR2, and DR4 with high affinity in a temperature- and time (and, in the case of DR4, pH)-dependent manner, and was competitively inhibited by DR-restricted peptides, but not by peptide derivatives that bind with low affinity. Bacterial superantigens inhibited Cop 1 binding only at very high concentrations. The formation of the Cop 1-DR1 complex was also shown by SDS-PAGE. These findings represent the first direct evidence for interactions of Cop 1 with purified DR molecules, and suggest that its effectiveness in experimental allergic encephalomyelitis and multiple sclerosis may be directly related to its binding in the groove of HLA-DR proteins.
IL-10 Regulates Liver Pathology in Acute MurineSchistosomiasis mansoniBut Is Not Required for Immune Down-Modulation of Chronic Disease
Authors: Wynn Thomas A. , Cheever Allen W. , Williams Megan E. , Hieny Sara , Caspar Pat , Kühn Ralf , Müller Werner , Sher Alan 
Published: January 2023

AbstractWe have used IL-10 gene knockout mice (IL-10T) to examine the role of endogenous IL-10 in the down-modulation of hepatic granuloma formation and lymphocyte responses that occurs in chronic infection with the helminth parasite Schistosoma mansoni. Although IL-10-deficient animals showed 20 to 30% mortality between 8 and 14 wk postinfection, they displayed no alterations in their susceptibility to infection and produced similar numbers of eggs as their wild-type littermates. The IL-10T mice displayed a significant increase in hepatic granuloma size at the acute stage of infection, which was associated with increased IFN-γ, IL-2, IL-1β, and TNF-α mRNA expression in liver and elevated Th1-type cytokine production by lymphoid cells. Despite developing an enhanced Th1-type cytokine response, the IL-10T mice showed no consistent decrease in their Th2-type cytokine profile. Surprisingly, although granulomatous inflammation was enhanced at the acute stage of infection, the livers of IL-10T mice displayed no significant increase in fibrosis and underwent normal immune down-modulation at the chronic stage of infection. Moreover, the down-modulated state could be induced in IL-10T mice by sensitizing the animals to schistosome eggs before infection, further demonstrating that the major down-regulatory mechanism is not dependent upon IL-10. We conclude that while IL-10 plays an important role in controlling acute granulomatous inflammation, it plays no essential role in the process of immune down-modulation in chronic schistosome infection.
Enhanced Expression of B7.2 (CD86) in Patients with Atopic Dermatitis: A Potential Role in the Modulation of IgE Synthesis
Authors: Jirapongsananuruk Orathai , Hofer Michaël F. , Trumble Anne E. , Norris David A. , Leung Donald Y. M. 
Published: January 2023

AbstractRecent studies have suggested that the accessory molecules B7.1 (CD80) and B7.2 (CD86) differ in their capacity to generate Th1 vs Th2 responses. Atopic dermatitis (AD) is a chronic allergic skin disease associated with increased IgE synthesis. To determine the potential role of B7.2 molecules in AD, the present study was conducted to compare the expression of B7.1 vs B7.2 on B cells from patients with AD vs normal subjects or patients with psoriasis. The expression of B7.2 on B cells of AD patients (53.67 ± 3.10%) was significantly higher than normals (38.02 ± 4.95%; p = 0.02) and psoriasis patients (40.19 ± 2.70%; p = 0.006). In contrast, there was no significant difference in B7.1 expression among the three subject groups. Interestingly, total serum IgE from AD patients and normal subjects correlated significantly with B7.2 expression on B cells (r = 0.68; p = 0.004), suggesting a role for B7.2+ B cells in IgE synthesis. Indeed, purified B7.2+ B cells produced significantly more IgE than B7.2− B cells in vitro (p = 0.04). Anti-human B7.2, but not B7.1, mAb significantly (p &lt; 0.05) decreased IgE production by PBMC stimulated with IL-4 and anti-CD40 mAb. Furthermore, B7.2+ B cells had a significantly higher level of IL-4R and CD23 expression than B7.1+ B cells. These data demonstrate the predominant expression of B7.2 in AD, but not psoriasis, and a novel role for this molecule in IgE synthesis.
Dystrophin Acts as a Transplantation Rejection Antigen in Dystrophin-Deficient Mice: Implication for Gene Therapy
Authors: Ohtsuka Yoshikazu , Udaka Keiko , Yamashiro Yuichiro , Yagita Hideo , Okumura Ko 
Published: January 2023

Abstract
Duchenne muscular dystrophy is a lethal and common X-linked recessive disease caused by a defect in dystrophin. Normal myoblast transplantation and dystrophin gene transfer have been expected to correct the deficiency in the muscles, but their clinical application has been hampered by the limited preservation of dystrophin-positive myofibers. In this study we investigated the mechanism for immunologic rejection of normal C57BL/10 (B10) myoblasts transplanted into dystrophin-deficient mdx mice, an animal model of Duchenne muscular dystrophy. We found that mdx mice develop CTL specific for dystrophin itself, which were CD8 dominant and restricted by H-2Kb. We identified several antigenic peptides derived from dystrophin that bind to H-2Kb and are recognized by the mdx anti-B10 CTL. Immunologic tolerance against dystrophin was successfully induced by i.v. injection of these peptides before B10 myoblast transplantation, which resulted in sustained preservation of dystrophin-expressing myofibers in mdx mice. These results demonstrate that dystrophin is antigenic in dystrophin-deficient mice and that immunologic regimen would be necessary to achieve the persistent expression of introduced dystrophin in the muscles of dystrophin-deficient individuals.
Differences in the Immune Response During the Acute Phase of E-55+ Murine Leukemia Virus Infection in Progressor BALB and Long Term Nonprogressor C57BL Mice
Authors: Panoutsakopoulou Vily , Little C. Scott , Sieck Thomas G. , Blankenhorn Elizabeth P. , Blank Kenneth J. 
Published: January 2023

Abstract
E-55+ murine leukemia virus infection of both progressor (BALB) and long term nonprogressor (C57BL) mouse strains is characterized by an acute and a persistent phase of infection. During the acute phase, progressor strains require CD8+ T cells to decrease virus burden, whereas the long term nonprogressor strains do not. In the present studies the immune response in BALB and C57BL mice during the acute phase of E-55+ murine leukemia virus infection was examined. The results demonstrate that BALB mice produce both IL-4 and IFN-γ, in contrast to C57BL mice, which produce only IFN-γ. In BALB mice, IL-4 production results in the absolute requirement for CD8+ T cells to reduce the virus burden during the acute phase of infection. The anti-virus immune response in these mice is IFN-γ dependent. On the other hand, C57BL mice do not produce IL-4 and, in the absence of both CD8+ T cells and IFN-γ, still generate an effective anti-virus immune response. Genetic studies suggest that these distinct immune responses are regulated by more than one non-MHC-linked gene. Two candidate regions that may encode this gene(s), located on chromosomes 7 and 19, respectively, were identified by recombinant inbred strain linkage analysis.