bluuebunny/crossref_metadata_2025_split huggingface dataset:
Involvement of mitogen-activated protein kinase pathways in the nuclear responses and cytokine production induced by Salmonella typhimurium in cultured intestinal epithelial cells.
Authors: Hobbie S , Chen L M , Davis R J , Galán J E 
Published: December 2022

Abstract
Central to the pathogenesis of Salmonella typhimurium is its ability to engage the host cell in a two-way biochemical interaction. As a consequence of this interaction, a dedicated protein secretion system, termed type III, is activated in these bacteria and directs the translocation of signaling proteins into the host cell. Secretion of these proteins stimulates host cell signal transduction pathways that lead to a variety of cellular responses. An important feature of S. typhimurium pathogenesis is the induction of a profound inflammatory response in the intestinal epithelium. In this report, we show that S. typhimurium induces host cell signal transduction pathways that lead to the activation of the transcription factors NF-kappaB and AP-1, resulting in the production of proinflammatory cytokines such as IL-8. We also show that S. typhimurium infection of cultured intestinal epithelial cells results in the activation of the mitogen-activated protein (MAP) kinases ERK, JNK, and p38. Induction of these signaling pathways and the synthesis of IL-8 was strictly dependent on the function of the invasion-associated type III protein secretion system encoded by S. typhimurium. Pretreatment of cells with the highly specific p38 MAP kinase inhibitor SB 203580 prevented S. typhimurium-induced IL-8 production. These results indicate that the inflammatory response induced by S. typhimurium may be due to the specific stimulation of MAP kinase signaling pathways leading to nuclear responses.
C1q augments platelet activation in response to aggregated Ig.
Authors: Peerschke E I , Ghebrehiwet B 
Published: December 2022

Abstract
Immune complexes and aggregated IgG (agg-IgG) induce platelet aggregation and the release reaction. Immune complexes also activate the complement system and interact with the complement component C1q. Since platelets possess both Fc and C1q receptors capable of signal transduction, the present study focused on the interaction between these binding sites and platelet activation. Subaggregating doses of agg-IgG (20-400 microg/ml) were identified for washed platelets from each of 11 healthy donors, and platelet aggregation was monitored in the presence or the absence of increasing concentrations of C1q (5-100 microg/ml). C1q produced a dose-dependent potentiation of platelet alphaIIb/beta3 integrin activation, platelet aggregation, and granule secretion when combined with low doses of agg-IgG. C1q alone was without effect. Maximal enhancement of agg-IgG-induced platelet activation was noted at C1q concentrations ranging from 50 to 100 microg/ml. The observed C1q-induced potentiation of platelet aggregation in response to agg-IgG was blocked by polyclonal antibody F(ab')2 directed against platelet binding sites recognizing the collagen-like domain of C1q (cC1qR) or by mAb Fab (IV.3) directed against platelet FcgammaRII receptors. These data suggest a cooperative interaction between platelet FcgammaRII and cC1q receptors and support a potential role for platelet cC1q receptors in pathologic platelet activation by circulating immune complexes often associated with in vivo thrombosis and thrombocytopenia.
Suppression of collagen-induced arthritis by continuous administration of IL-4.
Authors: Horsfall A C , Butler D M , Marinova L , Warden P J , Williams R O , Maini R N , Feldmann M 
Published: December 2022

Abstract
The onset of collagen-induced arthritis in DBA/1 mice is accompanied by a predominantly Th1 response, characterized by production of the proinflammatory cytokines IFN-gamma and TNF-alpha, and a predominance of IgG2a anti-collagen Abs. This study has primarily addressed the effects of continuous administration of exogenous IL-4, a Th2 cytokine, on collagen-induced arthritis in terms of time of onset, clinical symptoms, and histologic changes compared with those in untreated controls. The contributions of Th1 and Th2 cell responses were studied by examining anti-CII IgG subclasses, serum IgE levels, and cytokine production by synovial membrane and lymph node cell cultures. Continuous exposure to IL-4 for 28 days significantly delayed the onset of arthritis from 19 to 37 days and suppressed clinical symptoms. Arthritis occurred approximately 13 to 24 days after treatment ceased. Thereafter, the severity and duration of clinical symptoms were similar to those in control animals, although both joint damage and inflammation at the histologic and cellular levels were less severe than those in untreated controls. During IL-4 treatment, anti-collagen Ab levels were reduced (most significantly those of the IgG2a subclass), histology scores were lower, and the most striking effect was a 1000-fold decrease in TNF-alpha secretion by synovial cells. No significant differences in IgE levels were found between controls and IL-4-treated mice. These data suggest that the anti-inflammatory properties of IL-4 are mediated in part by down-regulation of Th1 responses rather than up-regulation of Th2 responses.
Ligation of the V7 molecule on T cells blocks anergy induction through a CD28-independent mechanism.
Authors: Soares L R , Rivas A , Tsavaler L , Engleman E G 
Published: December 2022

Abstract
Previous studies have demonstrated that a mAb that recognizes the leukocyte surface Ag V7 inhibits TCR/CD3-dependent T cell activation. In the current study, we demonstrate that in addition to inhibiting T cell proliferation and IL-2 production, anti-V7 blocks tyrosine phosphorylation of TCR/CD3-associated substrates. PMA overcomes this effect, and both PMA and exogenous IL-2 overcome anti-V7-mediated inhibition of T cell proliferation and IL-2 production. T cells stimulated with anti-CD3 in the absence of CD28 or V7 ligation become unresponsive (anergic) to restimulation with anti-CD3; T cells primed in the presence of either anti-V7 or anti-CD28 retain their ability to respond to restimulation with anti-CD3. When T cells are primed in the presence of optimal concentrations of anti-V7 and anti-CD28 Abs, they proliferate normally, indicating that the costimulatory signals generated through CD28 dominate the inhibitory signals generated through V7. However, as the anti-CD28 stimulus is diluted, the V7 effect becomes dominant and proliferation is inhibited. Thus, although both anti-V7 and anti-CD28 Abs prevent anergy, they induce distinct, competing intracellular signals. Wortmannin, which blocks phosphoinositol 3-kinase-dependent signaling, has little effect on V7-mediated inhibition, while herbimycin, an inhibitor of tyrosine kinase, synergizes with anti-V7 to inhibit T cell activation. On the basis of these findings, V7-mediated signals appear to inhibit TCR-dependent tyrosine kinases that are required for IL-2 production and cellular proliferation.
High affinity rheumatoid factor transgenic B cells are eliminated in normal mice.
Authors: Wang H , Shlomchik M J 
Published: December 2022

Abstract
Although systemic autoimmune diseases can be accompanied by multiple autoantibodies, certain specificities are dominant. Presumably, these specificities and their cognate Ags have properties that make them particularly amenable to autoimmune induction. Rheumatoid factors (RFs) are a dominant class of autoantibodies in rheumatoid arthritis and certain other autoimmune syndromes. To study the regulation of RFs in normal and autoimmune animals, we previously created a RF Ig transgenic model based on an RF isolated from an autoimmune MRL/lpr mouse. Using this model, called AM14, we were surprised to find that normal mice do not regulate disease-related RF B cells. This raised the question of whether RFs in general are not susceptible to tolerance induction, perhaps due to the unique properties of serum IgG and its FcRs. Alternatively, RFs can be tolerized, and the disease-related RFs are below the affinity threshold for such tolerance. To distinguish these possibilities, we generated a second RF transgenic model with the same specificity but much higher affinity than AM14. We found that, in contrast to AM14, high affinity RF B cells are subject to central tolerance, showing that there is not an absolute defect in RF B cell tolerance, but, rather, that RF B cell tolerance is affinity dependent even in normal animals. This is also the first model in which a disease-related specificity has been shown clearly to delete in a system in which Ag-positive and negative mice can be produced and compared.
Neutralizing IL-12 during induction of murine acute graft-versus-host disease polarizes the cytokine profile toward a Th2-type alloimmune response and confers long term protection from disease.
Authors: Williamson E , Garside P , Bradley J A , More I A , Mowat A M 
Published: December 2022

Abstract
Injection of parental spleen cells into BDF1 mice results in a graft-vs-host disease (GVHD), the nature of which is critically dependent on the parental haplotype. B6--&gt;BDF1 mice develop a Th1-mediated immunosuppressive lethal GVHD, whereas DBA/2--&gt;BDF1 mice develop a Th2-dependent chronic GVHD, characterized by autoantibody production and glomerulonephritis. In this study we show that neutralizing endogenous IL-12 for a brief period during the initiation of acute GVHD in B6--&gt;BDF1 mice not only confers long term protection from the acute disease, but also permits full repopulation of the recipient with donor B6 lymphocytes. Antibody-treated animals showed normal T cell proliferation in response to Con A stimulation and remained healthy throughout the study. Splenocytes from such mice showed reduced in vitro production of IFN-gamma and enhanced production of IL-5 and IL-10, suggesting a permanent switch from a Th1 to a Th2 cytokine response, comparable to that associated with chronic GVHD in DBA/2--&gt;BDF1 mice. In contrast to DBA/2--&gt;BDF1 mice, however, anti-IL-12-treated B6--&gt;BDF1 mice displayed only mild B cell hyper-responsiveness, as evidenced by a modest increase in serum IgG and IgE levels and moderate levels of anti-dsDNA Abs. Importantly, however, anti-IL-12-treated B6--&gt;BDF1 mice showed no evidence of immune complex-mediated glomerulonephritis. These results demonstrate that neutralizing IL-12 is an effective means of preventing acute GVHD and does not result in the development of chronic GVHD, which might otherwise limit its application.
Protein kinase C alpha-mediated chronic signal transduction for immunosenescence.
Authors: Ohkusu K , Du J , Isobe K I , Yi H , Akhand A A , Kato M , Suzuki H , Hidaka H , Nakashima I 
Published: December 2022

Abstract
In CD2/protein kinase C alpha (PKC alpha)-overexpressing human CD2/rabbit PKC alpha transgenic mice, an aging-dependent increase in PKC alpha expression and a decrease in proliferative responsiveness of splenic T cells were promoted. We found that an aging-associated accumulation of CD44(high) CD45RB(low) memory CD4+ T cells in exchange for CD44(low) CD45RB(high) naive CD4+ T cells was promoted in transgenic mice. A disequilibrium between Ag-dependent generation and subsequent elimination of memory T cells in these mice was shown to underlie this phenomenon. When stimulated with Ag, the PKC alpha transgenic mice responded poorly regarding Ab production and produced cytokines biased for high IFN-gamma/IL-12 and low IL-4/IL-10 levels. These results prove, for the first time, a causal role for chronic signal transduction through PKC alpha in aging-associated immunodysfunction and provide the first animal model for genetically promoted immunosenescence.
Perforin-dependent cytotoxic activity and lymphokine secretion by CD4+ T cells are regulated by CD8+ T cells.
Authors: Williams N S , Engelhard V H 
Published: December 2022

Abstract
Factors influencing the development of CD4+ T cell subpopulations with differing lymphokine profiles are well established. However, CD4+ cells can show both perforin- and Fas ligand-dependent cytotoxicity, and little is known about conditions favoring the development of these effector activities. We now report that CD8+ cells regulate the development of perforin-dependent cytotoxicity in CD4+ cells. CD4+ cells activated in either the presence or absence of CD8+ cells developed Fas ligand-dependent cytotoxic activity. However, CD4+ cells developed perforin-dependent cytotoxicity only in the absence of activated CD8+ cells. CD8+ cells also inhibited the development of IL-4-secreting CD4+ cells; however, there was no correlation between the expression of perforin-dependent cytotoxic activity and the ability to secrete IL-4, and perforin-dependent cytotoxic CD4+ cells represented only 10% of isolated clones. This suggests that the two characteristics are expressed in different CD4+ subsets and might be regulated by distinct effects of the CD8+ cells. In keeping with this, regulation of the lymphokine profile of CD4+ cells by CD8+ cells was consistent with mediation by IFN-gamma, but only when delivered at high concentrations requiring close proximity of the cells. In contrast, regulation of perforin-dependent cytotoxic activity of CD4+ cells by CD8+ cells seemed inconsistent with an IFN-gamma-dependent mechanism, suggesting either direct cell contact or close proximity to allow delivery of an unidentified soluble factor. The characteristics of perforin-dependent CD4+ CTL and their regulation by activated CD8+ cells suggest that they represent a previously unrecognized subpopulation that plays a defensive role when a CD8+ cell response is absent.
Superantigen activation of immune cells evokes epithelial (T84) transport and barrier abnormalities via IFN-gamma and TNF alpha: inhibition of increased permeability, but not diminished secretory responses by TGF-beta2.
Authors: McKay D M , Singh P K 
Published: December 2022

Abstract
Superantigens (SAgs) are extremely potent stimulants of T cell activity that have been implicated in the etiopathophysiology of inflammatory disease. Here, we tested the hypothesis that Staphylococcus aureus enterotoxin B (SEB), a model SAg, can alter epithelial transport and/or barrier functions via immune stimulation. Confluent monolayers of the human colonic T84 epithelial cell line, grown on filter supports, were cocultured with SEB +/- PBMC. Subsequently, T84 transport (consisting of baseline short-circuit current (Isc, indicates net ion transport) and secretory responses to carbachol and forskolin) and barrier functions (consisting of transepithelial resistance and fluxes of 3H-labeled mannitol and 51Cr-EDTA) were examined in Ussing chambers. T84 monolayers cocultured with SEB-activated PBMC displayed a time- and dose-dependent decrease in secretory responses to carbachol and forskolin and a significant increase in permeability. These dramatic changes in epithelial function were not due to reduced epithelial viability. Neutralizing Abs to IFN-gamma partially prevented the transport abnormalities, and Abs to TNF-alpha inhibited the increase in epithelial permeability. Abs to IL-1beta and IL-6 did not modulate the SEB-activated PBMC-induced T84 pathophysiology. Addition of TGF-beta2 to conditioned medium from SEB-activated PBMC partially inhibited the increase in T84 permeability but did not affect the transport abnormalities. We conclude that SAgs can elicit epithelial irregularities characteristic of enteric inflammation and that IFN-gamma and TNF-alpha are key mediators in this coculture model of epithelial dysfunction. Additionally, we would highlight the role that TGF-beta2 may play in preventing prolonged increases in epithelial permeability.
Identification of residues in the class II-associated Ii peptide (CLIP) region of invariant chain that affect efficiency of MHC class II-mediated antigen presentation in an allele-dependent manner.
Authors: Gautam A M , Yang M , Milburn P J , Baker R , Bhatnagar A , McCluskey J , Boston T 
Published: December 2022

Abstract
Invariant chain (Ii) associates with class II MHC molecules and is crucial for Ag presentation by class II molecules. A general explanation for how invariant chain (Ii) associates with polymorphic MHC class II molecules has been suggested by the crystallographic structure of CLIP (class II-associated Ii peptide) complexed with an HLA class II molecule, HLA-DR3. We show here that methionine residues at positions 93 and 99 in Ii are important in MHC class II-mediated Ag presentation, but function in an allele-dependent manner. Introduction of a Met--&gt;Ala mutation at position 99 in Ii (M99AIi) impaired presentation of peptides derived from exogenous proteins by I-Ad and I-Au class II molecules. Mutating Met--&gt;Ala in Ii at position 93 (M93AIi) abrogated presentation by I-Au molecules, but not by I-Ad. Impaired Ag presentation was associated with conformationally altered expression of I-A molecules on the surface of cells expressing mutated Ii. Cell surface CLIP staining and immunoprecipitation studies showed that both I-Ad and I-Au molecules were associated with an increased abundance of Ii peptides, CLIP, in cells expressing mutated Ii. These results show that methionine 93 and methionine 99 play an important physiologic role in Ii association with class II molecules by regulating release of CLIP from class II in the endocytic compartments to allow binding of cognate peptides.
DNA-binding antibodies from viable motheaten mutant mice: implications for B cell tolerance.
Authors: Westhoff C M , Whittier A , Kathol S , McHugh J , Zajicek C , Shultz L D , Wylie D E 
Published: December 2022

Abstract
C57BL/6 me(v)/me(v) (viable motheaten) mice have defective hemopoietic cell protein-tyrosine phosphatase (HCP, SHP-1) and are a model in which to study the role of this phosphatase in immune regulation and hemopoietic development. Immune defects in these mice include hypergammaglobulinemia, production of multiple autoantibodies, and glomerular nephritis. The presence of self-reactive Abs in these mice is an enigma, since it has been demonstrated that they have increased negative selection against self-reactive transgenic Abs. It was of interest to examine autoantibodies from these mice to identify reactivity or structural features that might account for their persistence and expansion in the repertoire. Abs to DNA were selected for investigation, since they have been characterized extensively from normal and autoimmune strains of mice. Viable motheaten mice had high titers of IgM, anti-dsDNA Abs, and all 12 anti-DNA hybridomas generated were also IgM. They had high avidity for dsDNA, also bound to ssDNA, but were not polyreactive. They used V(H) and V(L) gene families found in anti-DNA Abs from other strains, which reinforces evidence that there is preferential use of a restricted number of germline elements in anti-DNA Abs. The results indicate that Hcph-mutant mice do not delete DNA-reactive B cells, nor are they able to maintain these B cells in a state of anergy. Evidence for positive selection and clonal expansion after V-D-J rearrangement was also seen, in that several Abs expressed the same heavy chain in combination with different light chains, which is also a hallmark of the autoimmune anti-DNA response.
Characterization of lymphotoxin-alpha beta complexes on the surface of mouse lymphocytes.
Authors: Browning J L , Sizing I D , Lawton P , Bourdon P R , Rennert P D , Majeau G R , Ambrose C M , Hession C , Miatkowski K , Griffiths D A , Ngam-ek A , Meier W , Benjamin C D , Hochman P S 
Published: December 2022

Abstract
The lymphotoxin-alpha beta complex (LT alpha beta) is found on the surface of activated lymphocytes and binds to a specific receptor called the LT beta receptor (LT beta R). In the mouse, signaling through this pathway is important for lymph node development and splenic organization, yet the biochemical properties of murine LT alpha and LT beta are essentially unknown. Here we have used soluble receptor-Ig forms of LT beta R and TNF-R55 and mAbs specific for murine LT alpha, LT beta, and LT beta R to characterize the appearance of surface LT alpha beta complexes and LT beta R on several common murine cell lines. Cells that bound LT beta R also bound anti-LT alpha and anti-LT beta mAbs in a FACS analysis. The ability of these reagents to discriminate between surface TNF and LT was verified by analysis of surface TNF-positive, LPS-activated murine RAW 264.7 monocytic cells. Primary mouse leukocytes from spleen, thymus, lymph node, and peritoneum were activated in vitro, and CD4+ and CD8+ T cells as well as B cells expressed surface LT ligand but not the LT beta R. Conversely, elicited peritoneal monocytes/macrophages were surface LT negative yet LT beta R positive. This study shows that on mononuclear cells, surface LT complexes and receptor are expressed similarly in mice and man, and the tools described herein form the foundation for study of the functional roles of the LT system in the mouse.
Antagonism of Immunostimulatory CpG-Oligodeoxynucleotides by Quinacrine, Chloroquine, and Structurally Related Compounds
Authors: Macfarlane Donald E. , Manzel Lori 
Published: December 2022

Abstract
Phosphorothioate oligodeoxynucleotides containing CpG (CpG-ODN) activate immune responses. We report that quinacrine, chloroquine, and structurally related compounds completely inhibit the antiapoptotic effect of CpG-ODN on WEHI 231 murine B lymphoma cells and inhibit CpG-ODN-induced secretion of IL-6 by WEHI 231. They also inhibit IL-6 synthesis and thymidine uptake by human unfractionated PBMC induced by CpG-ODN. The compounds did not inhibit LPS-induced responses. Half-maximal inhibition required 10 nM quinacrine or 100 nM chloroquine. Inhibition was noncompetitive with respect to CpG-ODN. Quinine, quinidine, and primaquine were much less powerful. Quinacrine was effective even when added after the CpG-ODN. Near-toxic concentrations of ammonia plus bafilomycin A1 (used to inhibit vesicular acidification) did not reduce the efficacy of the quinacrine, but the effects of both quinacrine and chloroquine were enhanced by inhibition of the multidrug resistance efflux pump by verapamil. Agents that bind to DNA, including propidium iodide, Hoechst dye 33258, and coralyne chloride did not inhibit CpG-ODN effect, nor did 4-bromophenacyl bromide, an inhibitor of phospholipase A2. Examination of the structure-activity relationship of seventy 4-aminoquinoline and 9-aminoacridine analogues reveals that increased activity was conferred by bulky hydrophobic substituents on positions 2 and 6 of the quinoline nucleus. No correlation was found between published antimalarial activity and ability to block CpG-ODN-induced effects. These results are discussed in the light of the ability of quinacrine and chloroquine to induce remission of rheumatoid arthritis and lupus erythematosus.