bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dissociation between cytokine mRNA expression and protein production in shigellosis
Authors: Raqib Rubhana , Ljungdahl Åke , Lindberg Alf A. , Wretlind Bengt , Andersson Ulf , Andersson Jan 
Published: March 2007

AbstractIn our study, infection with Shigella dysenteriae type 1 (n = 16) or Shigella flexneri in adults (n = 5) was associated with a gradual accumulation of mRNA for interleukin (IL)‐1β, tumor necrosis factor (TNF)‐α, IL‐6, transforming growth factor‐β, IL‐10, IL‐4, TNF‐β, interferon (IFN)‐γ and perforin in the rectal biopsy samples during the convalescent stage of the disease demonstrated by in situ hybridization. In contrast, immunohistochemical staining in rectal tissues of cytokine protein‐producing cells at the single‐cell level exhibited a steady‐state expression during 2–36 days after the onset of the disease. The frequency of cytokine mRNA‐expressing cells varied in the range of 3–100‐fold higher than that of the corresponding protein‐synthesizing cells. The accumulation of cytokine mRNA in vivo during shigellosis represented a long‐lasting phenomenon throughout the disease course, and may be linked to its immunopathogenesis. The results also indicate that assessment of both protein and mRNA in vivo may provide complementary information. Stimulation in vitro of peripheral blood mononuclear cells from normal healthy donors with Shigella‐derived lipopoly‐saccharide or shiga toxin was carried out to elucidate the role of Shigella antigens in the regulation of translation of cytokine‐specific mRNA. The incidence of cytokine (IFN‐γ, IL‐6 and TNF‐α) mRNA‐ and cytokine protein‐expressing cells was very similar and congruent after both these Shigella‐derived stimuli. We could, thus, not find evidence for shiga toxin‐induced down‐regulation of cytokine mRNA translation as the explanation for the observed discrepancy between cytokine mRNA and protein levels in the tissue biopsies.
Human dendritic cells activate T lymphocytes via a CD40: CD40 ligand‐dependent pathway
Authors: McLellan Alexander D. , Sorg Rüdiger V. , Williams Lisa A. , Hart Derek N. J. 
Published: March 2007

AbstractThe CD40: CD40 ligand (CD40L) interaction provides T lymphocyte‐mediated help for B lymphocyte and monocyte function but has also been shown to serve as a co‐stimulus for T lymphocyte activation. In this report, we studied the regulation of CD40 expression and its functional relevance for the human dendritic cell (DC) stimulation of T lymphocytes. Only a small subpopulation of directly isolated blood DC expressed CD40. However, CD40 was rapidly up‐regulated by culture, and its expression was further enhanced by interleukin (IL)‐1α, IL‐1β, IL‐3, tumor necrosis factor‐α and granulocyte/macrophage‐colony‐stimulating factor. Expression of CD40L on DC was not detected. The proliferation of T lymphocytes in an allogeneic mixed leukocyte reaction, stimulated by blood DC or epidermal Langerhans cells, was significantly reduced in the presence of the CD40 immunoglobulin (CD40Ig) fusion protein or CD40L monoclonal antibodies. Cross‐linking of CD40 on directly isolated DC with mouse CD40L trimer (mCD40LT) markedly augmented CD80 and CD86 up‐regulation. Nevertheless, the same cross‐linking mCD40LT inhibited DC stimulated T lymphocyte proliferation. When CD40Ig was added simultaneously with CTLA‐4Ig, only minimal and variable additional inhibition of DC‐stimulated allogeneic T lymphocyte proliferation and IL‐2 secretion was observed, compared to each fusion protein alone. These results suggest that both CD80/CD86‐dependent and ‐independent components of DC‐T lymphocyte CD40: CD40L co‐stimulation exist and further emphasize that the majority of blood DC have to differentiate or be activated to express co‐stimulatory molecules.
Death of germinal center B cells without DNA fragmentation
Authors: Nakamura Masanori , Yagi Hideki , Kayaba Shoichi , Ishii Tadashi , Gotoh Takahiro , Ohtsu Susumu , Itoh Tsunetoshi 
Published: March 2007

AbstractDuring the selection of B cells within germinal centers (GC) on the basis of their affinity for T‐dependent antigen, B cells not positively selected are eliminated within GC. This process of B cell death has been considered to be apoptosis. In a recent study, we have reported that, although a substantial number of thymocytes were considered to be dead because of their extremely small cell size and heavy chromatin condensation even though they were not yet phagocytosed (pyknosis), they were devoid of DNA fragmentation, the most characteristic feature for apoptosis. In this study, we examined in vivo the mechanism of B cell death within GC by using the terminal deoxynucleotidyl transferase (TdT)‐mediated dUTP‐biotin nick end‐labeling (TUNEL) method to detect DNA double‐strand breaks. TUNEL+ B cells were scattered throughout the upper dark and the light zones of GC. Double staining of the sections by the TUNEL method and acid phosphatase (AcP) activities showed that all the TUNEL+ B cells were phagocytosed by macrophages. Light microscopic and ultrastructural studies revealed the presence of small unphagocytosed B cells within the light zone. These cells are undoubtedly dead because they were much smaller than surrounding lymphoid cells and have a heavy chromatin condensation. Furthermore, ultrastructural detection of DNA fragmentation confirmed that these small unphagocytosed B cells were TUNEL−, implying that DNA fragmentation is not primarily involved in the cell death process of these small dead B cells. These results indicate that most B cells, not positively selected and thus destined to be eliminated, die within GC without DNA fragmentation, and are subsequently phagocytosed by macrophages and become TUNEL+. Typical apoptosis, characterized by DNA fragmentation in situ, is not the predominant type of cell death that occurs during the selection of B cells in GC.
CD28‐dependent killing by human YT cells requires phosphatidylinositol 3‐kinase activation
Authors: Lu Yiling , Rodriguez Ron , Bjorndahl Jay , Phillips Catherine A. , Trevillyan James M. 
Published: March 2007

AbstractCD28/B7 interactions have been demonstrated to provide a co‐stimulatory signal for the generation of CD8+ cytotoxic T lymphocytes in the absence of CD4+ T helper cells. The CD28 signals required for induction of cytotoxicity have yet to be described. To investigate further the biochemical signaling pathways associated with CD28‐dependent cytotoxicity, we have studied the human thymic leukemia cell line, YT. YT cells kill B7+ targets in a non‐major histocompatibility complex (MHC)‐restricted, CD28‐dependent manner. CD28 ligation on the surface of YT cells caused a rapid increase in the tyrosine phosphorylation of four major cellular substrates with masses estimated to be 110, 95, 85, and 44 kDa. The 110 and 85 kDa substrates were identified as the catalytic and regulatory subunits, respectively, of phosphatidylinositol 3‐kinase (PI3‐K). Engagement of CD28 caused the rapid receptor association and activation of PI3‐K but did not activate phospholipase Cγ. CD28‐induced tyrosine phosphorylation and PI3‐K activation was independent of p56lck protein tyrosine kinase (PTK) activity (previously reported to be associated with CD28) and was insensitive to inhibition by the PTK inhibitor herbimycin A. Two structurally and mechanistically dissimilar inhibitors of PI3‐K, wortmannin and 2‐(4‐morpholinyl)‐8‐phenyl‐4H‐1‐benzopyran‐4‐one (LY294002) also failed to block CD28‐dependent tyrosine phosphorylation events or the association of PI3‐K with the CD28 receptor. However, both drugs inhibited CD28‐dependent cytotoxicity and CD28 receptor associated PI3‐K activity with IC50 values similar to the reported IC50 values for PI3‐K inhibition. Although herbimycin A did not significantly block the observed CD28‐dependent tyrosine phosphorylation or PI3‐K activation, herbimycin did block CD28‐dependent cytotoxicity in a dose‐dependent manner. These data support a role for PI3‐K activation in the CD28‐dependent initiation of cytotoxic effector function and suggest that a herbimycin sensitive step(s) is either CD28‐independent, resides within a PI3‐K‐independent CD28 signaling pathway, or is downstream of CD28‐dependent PI3‐K activation.
Immune complex‐induced interleukin‐6, interleukin‐10 and prostaglandin secretion by human monocytes: a network of pro‐ and anti‐inflammatory cytokines dependent on the antigen: antibody ratio
Authors: Berger Stefan , Balló Hilmar , Stutte Hans Jochen 
Published: March 2007

AbstractWe have used two experimental models of immune complexes to study the secretion of interleukin (IL)‐10, IL‐6 and their connection with the immune complex‐induced synthesis of prostaglandin (PG) E2 by human monocytes in vitro. Immune complexes formed of tetanus toxoid and polyclonal anti‐tetanus toxoid antiserum as well as heat‐aggregated human serum immunoglobulins induced the release of IL‐6 and IL‐10 in a dose‐ and antigen: antibody ratio‐dependent manner. Antigen‐antibody complexes formed near equivalence were most effective in induction of a cytokine response. PGE2 could augment the immune complex‐induced IL‐6 and IL‐10 secretion, but alone, did not induce cytokine secretion. IL‐10 was capable of down‐regulating the release of IL‐6 and PGE2. Additionally, we demonstrated that endogenously synthesized IL‐10 limited the immune complex‐induced secretion of proinflammatory cytokines tumor necrosis factor‐α and IL‐1β. All three regulatory factors examined here share anti‐inflammatory properties and are closely associated with the T helper type 2 (Th2) immune response. We conclude that immune complexes, besides their well‐known ability no cause acute and chronic inflammation, can mediate immunosuppressive effects and influence the balance of Th1/Th2 responses.
Affinity maturation and hypermutation in a simulation of the humoral immune response
Authors: Celada Franco , Seiden Philip E. 
Published: March 2007

AbstractBy experimenting with a cellular automaton model of the immune system, we have reproduced affinity maturation of the antibody response, a somatic adaptation to a changing environment. The simulation allowed the isolation of a number of variables, e.g. the fraction of repertoire available, the magnitude of the change in affinity with mutation, the mutation frequency and its focus on the complementarity‐determining regions (CDR) of the antibody. Multiple series of immunizations were run in machina where the contribution of each variable was evaluated against the maturation observed. We found that hypermutation is not necessary for affinity maturation if the repertoire of B cell specificities is sufficiently complete, but is essential when the B cell diversity is limited (which happens to be the case in vivo), as it fills the holes in the repertoire and allows selection by antigen. Maturation also depends on the magnitude of the change in affinity with mutation, and we supply some necessary limits on this parameter. For mutations confined to the CDR, the most efficient maturation occurs at mutation rates of 0.2 per paratope and per cell division. When mutations also affect the framework regions, the peak of the most effective CDR mutation rate moves progressively to lower values. A most sensitive parameter is the speed of maturation, which reflects the rate of expansion of mutated clones. Comparing it with biological observations can help to discriminate between alternative hypotheses on the phenomena of hypermutation and affinity.
Evidence of a T helper type 2 activation in human schistosomiasis
Authors: Araújo Maria Ilma , de Jesus Amélia Ribeiro , Bacellar Olívia , Sabin Elizabeth , Pearce Edward , Carvalho Edgar M. 
Published: March 2007

AbstractThe lymphocyte proliferative response and cytokine production to S. mansoni antigen in vitro were evaluated in 22 schistosomiasis patients living in an area endemic for this disease. The majority of patients (86%) showed no lymphocyte proliferative response and none of them showed interferon‐γ (IFN‐γ) production, following in vitro stimulation with soluble adult worm antigen preparation (SWAP). In contrast, interleukin (IL)‐5 (2038 ± 1757 pg/ml) and IL‐10 (867 ± 762 pg/ml) were detected in peripheral blood mononuclear cell (PBMC) cultures stimulated with SWAP. Moreover, mRNA for IL‐4 was detected in SWAP‐stimulated PBMC from 4 of 6 patients evaluated. Restoration of lymphoproliferative response was achieved in 4 of 6 patients by adding anti‐IL‐10 monoclonal antibody (mAb) to PBMC cultures [mean stimulation index (SI) in the presence of antigen = 2.7 ± 2.9; SI in the presence of antigen plus anti‐IL‐10, 21 ± 16]. Restoration of IFN‐γ production by addition of anti‐IL‐10 mAb was achieved in 4 of 12 patients evaluated (248, 350, 687 and 710 pg/ml). Moreover, the addition of IL‐10 to PBMC cultures of 3 schistosomiasis patients and 2 cured subjects who had high lymphoproliferative responses to SWAP resulted in the suppression of these responses by 90%, and completely suppressed IFN‐γ production in one of the subjects, whose PBMC produced IFN‐γ after stimulation with SWAP. The presence of IL‐4 mRNA, high levels of IL‐5, and the absence of IFN‐γ in PBMC culture supernatants from infected patients, supports the conclusion that patients living in an endemic area of schistosomiasis express a predominant T helper type 2 response. The high levels of IL‐10 and the ability of neutralizing anti‐IL‐10 mAb to restore T cell responses indicate that this cytokine plays an important role in the modulation of T cell responses in schistosomiasis.
Mercury induces polyclonal B cell activation, autoantibody production and renal immune complex deposits in young (NZB × NZW)F1 hybrids
Authors: Al‐Balaghi Sanad , Möller Erna , Möller Göran , Abedi‐Valugerdi Manuchehr 
Published: March 2007

AbstractIt is well established that in susceptible mouse strains, chronic treatment with subtoxic doses of mercuric chloride (HgCl2) induces a systemic autoimmune disease, which is characterized by increased serum levels of IgG1 and IgE antibodies, by the production of anti‐nucleolar antibodies and by the development of immune complex‐mediated glomerulonephritis. Susceptibility to mercury is partly under the control of major histocompatibility complex genes. To study the susceptibility to mercury further, we investigated the in vivo effects of mercury in young autoimmune disease prone (NZB × NZW)F1 (H‐2d/z) mice prior to establishment of spontaneous autoimmune disease. Mercury‐susceptible SJL (H‐2s) mice and mercury low‐responder BALB/c (H‐2d) mice were used as positive and negative controls, respectively. In (NZB × NZW)F1 mice, treatment with mercury stimulated an intense antibody formation characterized by increased numbers of splenic IgG1 and IgG3 antibody‐producing cells as well as by elevated serum IgE levels. Injection with mercury also induced an increased production of IgG1, IgG2b and IgE antibodies in SJL, but not in BALB/c mice. The mercury‐induced IgG1 response in (NZB × NZW)F1 and SJL mice was found to be polyclonal and autoantibodies against double‐stranded (ds)DNA, IgG, collagen, cardiolipin, phosphatidylethanolamine as well as antibodies against the hapten trinitrophenol were produced. In addition, SJL, but not (NZB × NZW)F1 or BALB/c mice, produced IgG1 anti‐nucleolar antibodies after treatment with mercury. Further studies demonstrated that (NZB × NZW)F1 and SJL mice developed high titers of renal mesangial immune complex deposits containing IgG1 antibodies 3 weeks after injection with mercury. Thus, a mouse strain genetically prone to develop spontaneous autoimmune diseases is highly susceptible to mercury‐induced immunopathological alterations.
CD40‐mediated regulation of interleukin‐4 signaling pathways in B lymphocytes
Authors: Siepmann Kirsten , Wohlleben Gisela , Gray David 
Published: March 2007

AbstractThe importance of cytokines in controlling immunoglobulin isotype switching is well known. Given the defect in switching to IgG, IgA and IgE isotypes in mice and humans that carry mutations in the CD40 and CD40 ligand genes, we have investigated the role of CD40 ligation in controlling B cell responses to interleukin (IL)‐4. We have found that CD40‐mediated signals cause a fivefold up‐regulation of IL‐4 receptor (IL‐4R) on the B cell surface and that this is associated with a 100–1000‐fold increase in the cells' responsiveness to the cytokine. While we found no evidence of increased affinity or structural change of the receptor, we do find that prestimulation of B cells with anti‐CD40 antibodies brings about several changes in the IL‐4 signaling pathways. Subsequent delivery of IL‐4 to CD40‐prestimulated cells provokes intracellular signals distinct from those induced in resting B cells in response to IL‐4. While resting B cells phosphorylate Jak3 kinase shortly after IL‐4 activation, cells pre‐incubated with anti‐CD40 exhibit active dephosphorylation of this molecule and phosphorylation of proteins of around 45 kDa upon addition of IL‐4. The common γ chain, Jak3 and Jak1 can all be immunoprecipitated in normal amounts with the IL‐4R chain after CD40 prestimulation. We show that the observed dephosphorylation of Jak3 may be due to a stable association with the src‐homology protein tyrosine phosphatase SH‐PTP2. In contrast, the enzyme appears to be inactive and to dissociate very quickly from the signaling complex in cells that are stimulated with IL‐4 alone.
Interferon‐γ confers resistance to experimental allergic encephalomyelitis
Authors: Krakowski Michelle , Owens Trevor 
Published: March 2007

AbstractIn experimental allergic encephalomyelitis (EAE), T cells infiltrate the central nervous system (CNS) and induce inflammation. These CD4+ T cells secrete interferon (IFN)‐γ, levels of which correlate with disease severity, and which is proposed to play a key role in disease induction. Many strains of mice are resistant to EAE. We have studied the effect of deletion of IFN‐γ on the ability to induce EAE in resistant BALB/c‐backcrossed mice. As expected, only 0–6 % of BALB/c or BALB/c‐backcrossed mice developed EAE when immunized with myelin basic protein in adjuvant. Strikingly, abrogation of IFN‐γ expression by targeted disruption of the IFN‐γ gene (GKO mice) converted them to a susceptible phenotype. As many as 71 % of these IFN‐γ‐deficient mice developed EAE, a frequency comparable to that seen with the susceptible SJL/J strain. In addition, EAE was of unusually high severity in mice lacking IFN‐γ. Immunological characteristics of disease in IFN‐γ‐deficient mice were comparable to those seen in susceptible (SJL/J) mice with EAE, including perivascular infiltration in the CNS and order‐of‐magnitude increases for both CD3 γ chain and TNF‐α mRNA levels in the spinal cord. We thus demonstrate that lack of IFN‐γ converts an otherwise EAE‐resistant mouse strain to become susceptible to disease. Therefore, in BALB/c mice, IFN‐γ confers resistance to EAE.
Interferon‐γ‐inducing factor enhances T helper 1 cytokine production by stimulated human T cells: synergism with interleukin‐12 for interferon‐γ production
Authors: Micallef Mark J. , Ohtsuki Takashi , Kohno Keizo , Tanabe Fujimi , Ushio Shimpei , Namba Motoshi , Tanimoto Tadao , Torigoe Kakuji , Fujii Mitsukiyo , Ikeda Masao , Fukuda Shigeharu , Kurimoto Masashi 
Published: March 2007

AbstractThe novel cytokine interferon‐γ‐inducing factor (IGIF) augments natural killer (NK) cell activity in cultures of human peripheral blood mononuclear cells (PBMC), similarly to the structurally unrelated cytokine interleukin (IL)‐12. IGIF has been found to enhance the production of interferon‐γ (IFN‐γ) and granulocyte/macrophage colony‐stimulating factor (GM‐CSF) while inhibiting the production of IL‐10 in concanavalin A (Con A)‐stimulated PBMC. In this study, when anti‐CD3 monoclonal antibody (mAb)‐stimulated human enriched T cells were exposed to IGIF, the cytokine dose‐dependently enhanced the proliferation of the cells and this could be completely inhibited by a neutralizing antibody against IL‐2 at lower concentrations of IGIF. Neutralizing antibody against IFN‐γ had only insignificant inhibitory effects on T cell proliferation at higher concentrations of IGIF. Enzyme‐linked immunosorbent assays (ELISA) revealed that, like PBMC, T cells exposed to IGIF produced large amounts of IFN‐γ; however, changes in the production of IL‐4 and IL‐10 were minimal. IGIF, but not IL‐12, significantly enhanced IL‐2 and GM‐CSF production in T cell cultures, as determined by CTLL‐2 bioassay and ELISA, respectively; however, both IGIF and IL‐12 enhanced IFN‐γ production by the T cells. When T cells were exposed to a combination of IGIF and IL‐12, a synergistic effect was observed on the production of IFN‐γ, but not on production of IL‐2 and GM‐CSF. In conclusion, IGIF enhances T cell proliferation apparently through an IL‐2‐dependent pathway and enhances Th1 cytokine production in vitro and exhibits synergism when combined with IL‐12 in terms of enhanced IFN‐γ production but not IL‐2 and GM‐CSF production. Based on structural and functional differences from any known cytokines, it was recently proposed that this cytokine be designated interleukin‐18.
Interferon‐γ is required during the initiation of an organ‐specific autoimmune disease
Authors: Barrett Simon P. , Gleeson Paul A. , De Silva Harini , Toh Ban‐Hock , van Driel Ian R. 
Published: March 2007

AbstractAutoimmune gastritis induced by neonatal thymectomy of mice is a CD4+ T cell‐mediated organ‐specific autoimmune disease. The characteristic features of autoimmune gastritis, which include a mononuclear infiltrate within the gastric mucosa, loss of parietal and chief cells and circulating autoantibodies to the gastric H+/K+ ATPase, appear 6–10 weeks after thymectomy. Here we have assessed the role of interferon‐γ (IFN‐γ) in the pathogenesis of the gastric lesion. Splenic T cells derived from mice with gastritis produced three‐ to tenfold more IFN‐γ than T cells from normal animals after stimulation with anti‐CD3 antibodies. Treatment of neonatally thymectomized mice at weekly intervals for 6 or 12 weeks with a neutralizing rat monoclonal antibody to mouse IFN‐γ abolished the production of anti‐gastric autoantibodies and decreased the incidence of gastric mononuclear infiltrates from the 69% observed in normal rat immunoglobulin (Ig)‐injected mice to 16%. Further, in mice treated with only a single dose of anti‐IFN‐γ immediately after thymectomy at 3 days after birth, the incidence of autoimmune gastritis was 1/19 compared to 8/19 in normal rat Ig‐injected mice. Prevention of autoimmunity by neutralization of IFN‐γ several weeks prior to the detection of a pathological lesion strongly suggests that IFN‐γ plays an essential role in the initiation of the gastric autoimmune response.