Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human skin fibroblasts synthesize and secrete complement Factor B, a component of the complement alternative pathway, when stimulated by mediators of inflammation such as lipopolysaccharide and various cytokines. Recombinant IL-6/IFN-beta 2 (E. coli) stimulates Factor B synthesis in fibroblasts but the effect is strongly potentiated by the addition of IFN-gamma. When both cytokines are added, the skin fibroblasts secrete significant amounts of biologically active Factor B detectable in a hemolysis test. This cooperative effect of IL-6, which is made by most tissue cells and monocytes and of IFN-gamma which is made by T-lymphocytes may play a role in local inflammatory processes. IL-6 and IFN-gamma also cooperate in the induction of (2'-5') A synthetase, a mediator of IFN action.
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PMID:Induction of complement factor B activity in human fibroblasts by IL-6/IFN-beta 2 and IFN-gamma. 256 27

The suppressive effects of mouse recombinant interferon-beta (IFN-beta) on B cell differentiation of MRL/Mp-lpr/lpr (MRL/1) mouse, a model of autoimmune diseases, and C3H/H2 mice, a normal situation, were investigated. Spleen mononuclear cells were cultured in the presence of lipopolysaccharide (LPS), and the suppressive effect of IFN-beta was examined on differentiation of B cells to plaque-forming cells (PFCs) by highly sensitive reversed hemolytic plaque assay. IFN-beta (5,000-10,000 units/ml) suppressed more than 50% of PFCs of both MRL/1 and C3H/H2 mice. This suppressive activity as well as the cytotoxicity of natural killer (NK) cells enhanced by IFN-beta was abrogated by treatment of the spleen cells with anti-asialo GM1 antibody in the presence of complement. This suppressive activity was also abrogated by intravenous administration of 20 microliter/mouse of anti-asialo GM1 12 hr before cultivation of spleen cells. These results suggest that NK cells activated by IFN might be responsible for the immunoregulation in autoimmune diseases.
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PMID:Suppressive effect of interferon-beta-activated natural killer cells on lipopolysaccharide-induced B cell differentiation of MRL/Mp-lpr/lpr mice. 259 77

Interleukin-1 (IL-1), a modulatory protein with immune and inflammatory functions, is spontaneously released by tissue macrophages in lower concentrations compared with peripheral blood monocytes. Conversely, in idiopathic pulmonary fibrosis, sarcoidosis, and certain inflammatory diseases, increased amounts of IL-1 are released by alveolar macrophages (AM). We examined IL-1 production by AM from patients with adult respiratory distress syndrome (ARDS) and compared it with that in patients with severe pneumonia requiring assisted ventilation, patients with pneumonia requiring parenteral antibiotics, and healthy control subjects. In vitro, ARDS AM released significantly more total IL-1 and IL-1 beta than did ARDS AM in patients with pneumonia and in control subjects. Moreover, after stimulation of these cells with 10 micrograms/ml of lipopolysaccharide (LPS), ARDS AM significantly increased release of IL-1 and IL-1 beta. AM from patients with severe pneumonia also released greater amounts of both IL-1 and IL-1 beta as fresh explants and after LPS stimulation when compared with control subjects. Incubation of AM with 250 U/ml human interferon-gamma (gamma IFN) was associated with less IL-1 beta release. However, stimulating AM from patients with ARDS and severe pneumonia with gamma IFN plus LPS enhanced the release of IL-1 beta compared with that in patients with pneumonia and in control subjects. ARDS AM released significantly more IL-1 beta than did all of the other groups. These results demonstrate that AM from patients with ARDS are capable of releasing significantly greater amounts of IL-1, which may be related to the progression of acute lung injury.
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PMID:Elevated interleukin-1 release by human alveolar macrophages during the adult respiratory distress syndrome. 260 96

Recent studies have identified some of the early molecular transductional events, which occur during the activation of murine macrophages. Our current evidence indicate a central role for protein kinase C for the priming effect of interferon-gamma (IFN gamma). IFN gamma also initiates Na+/H+ exchange and 45Ca efflux from murine macrophages (cascade I). Our data further indicate the involvement of multiple transductional pathways in the actions of bacterial lipopolysaccharide (LPS). Specifically, molecular events involved in the action of LPS include production of inositol phosphates and calcium mobilization as well as IFN gamma-regulated alterations in intracellular pH (cascade II). Our data further indicate that additional transductional events (e.g., synthesis of early or competence proteins) in response to LPS (cascade III) are also necessary for macrophage activation. Finally, regulation of important surface (e.g., Ia) and secreted molecules (TNF or IL-1) is exerted at the levels of both transcription and stabilization of specific mRNA in response to transductional cascades I, II and III. Taken together, the data indicate macrophage activation is complexly regulated at multiple levels.
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PMID:Molecular events in the activation of murine macrophages. 265 10

The interaction between human endothelial cells and leukocytes during immunological and inflammatory responses is in part mediated through the release of soluble mediators. We report that cultured human umbilical vein endothelial cells secrete IL-6 when stimulated with lipopolysaccharide. The monokines, IL-1 and TNF-alpha, were potent inducers of IL-6, whereas lymphotoxin was only effective at much higher concentrations. IFN gamma also was a strong stimulus of IL-6 production, but TGF-beta did not have an effect at doses modulating other endothelial cell functions. Endothelial cell IL-6 was active as hybridoma-plasmacytoma growth factor and as B-cell and hepatocyte stimulating factor. Endothelial IL-6 activity was neutralized by a specific antibody to IL-6 and it was shown by immunoprecipitation to be identical in size to human fibroblast-derived IL-6. IL-6 did not have a detectable effect on several endothelial cell functions, including proliferation, adherence of leukocytes, and synthesis of PGE2, TPA, and PAI-1. As IL-6 is probably an important regulator of host defense responses, production of this cytokine by endothelial cells may contribute to the pathogenesis of various inflammatory and immunologic diseases.
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PMID:Human endothelial cells produce IL-6. Lack of responses to exogenous IL-6. 266 Jun 97

Macrophages (Mphi) and Mphi-depleted (nonadherent) nonparenchymal cells (NPC) of the liver were examined for their cytotoxic potential against tumor cells, production of tumor necrosis factor (TNF), and release of prostaglandins (PG) following stimulation by lipopolysaccharide (LPS), interferon-gamma (IFN gamma), and zymosan. Resident murine liver macrophages had no natural cytotoxicity for the TNF-resistant target cell line P815. Activation of these cells was only obtained by a combination of IFN gamma and LPS. Inflammatory murine macrophages were in a primed stage and could be activated by LPS alone in the absence of IFN gamma. Rat resident macrophages resembled functionally the inflammatory macrophages of the mouse liver rather than the resident macrophages. They displayed natural cytotoxicity against all targets tested and were further activated by LPS in the absence of IFN gamma. Similar results were obtained with respect to macrophage-depleted nonadherent NPC: Mouse NPC had a low level of NK activity against Yac-1 cells. Treatment with pyran copolymer resulted in a strong increase of cytotoxicity against Yac-1; furthermore, a TNF-dependent killing of Wehi 164 and TNF-independent cytotoxicity against P815 cells were now acquired. In the rat NPC prepared from unstimulated animals expressed high levels of natural cytotoxicity against all targets. No major differences could be observed between inflammatory Mphi and Kupffer cells of rat and mouse liver with regard to TNF production and TNF-dependent killing of Wehi 164 tumor cells. The same was true for the spectrum of secreted prostanoids. Upon activation of all cell populations a marked shift toward the production of PGE2 occurred. Experiments involving the cyclooxygenase inhibitor indomethacin showed enhanced TNF-dependent tumor cell killing by nonactivated Mphi in the absence of prostanoid production.
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PMID:Comparative study of cytotoxicity, tumor necrosis factor, and prostaglandin release after stimulation of rat Kupffer cells, murine Kupffer cells, and murine inflammatory liver macrophages. 278 25

We have investigated the effects of murine interferons on the ability of rat alveolar macrophages (AM) to inhibit the proliferation of the intracellular protozoan Toxoplasma gondii. This activity was determined by measuring suppression of 3H-uracil uptake into the Toxoplasma and by microscopic enumeration of the intracellular organisms. Recombinant gamma interferon (rMulFN-gamma), but not alpha/beta interferon (IFN-alpha/beta) was able to activate AM for antimicrobial activity in vitro. Maximum activation was achieved by incubation with 50-200 units/ml rMulFN-gamma and the activity was lost at one unit/ml. The highest levels of activation were obtained when macrophages were incubated with interferon for 48-72 h prior to the challenge with Toxoplasma organisms. Activation could still be obtained, however, when the interferon was added to the cultures as late as 2 h after the phagocytosis of Toxoplasma. Neither MDP nor low concentrations (1-1-ng/ml) of S. typhosa lipopolysaccharide (LPS) were able to activate these cells to inhibit the growth of Toxoplasma. Phagocytosis of Toxoplasma by AM did not result in the release of O2-, in fact the spontaneous release of O2- by these cells was inhibited by Toxoplasma. This inhibition was reversed by preincubation of the cells with rMulFN-gamma.
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PMID:Activation of rat alveolar macrophages by gamma interferon to inhibit Toxoplasma gondii in vitro. 282 44

Although the interferon-gamma (IFN-gamma) receptor on murine and human mononuclear phagocytes has been defined and partially characterized, very little data exists which describes the ultimate fate of receptor-bound ligand. The current studies were specifically designed to define the metabolic processes which act on murine recombinant IFN-gamma following its interaction with murine macrophages at physiologic temperatures. Ligand internalization was demonstrated by comparing binding of [125I]IFN-gamma to macrophages at 4 degrees C and 37 degrees C. When binding was carried out at 4 degrees C, 96% of the cell-associated [125I]IFN-gamma remained accessible at the plasma membrane and could be stripped from the cell by exposure to pronase. In contrast, at 37 degrees C, only 35% of the cell-associated radioactivity was pronase strippable. Macrophages degraded [125I]IFN-gamma into trichloroacetic acid-soluble material at 37 degrees C at a constant rate of 7000 molecules/cell/hr over a 12-hr time period. The amount of IFN-gamma degraded correlated with the amount of IFN-gamma bound to the cell surface. The receptor was neither up- nor down-regulated by ligand or by other agents known to regulate macrophage functional activity such as IFN-alpha, IFN-beta, lipopolysaccharide, or phorbol myristate acetate. The constant uptake of IFN-gamma by macrophages was due to the presence of an intracellular receptor pool (62% of the total receptor number) and to a mechanism of receptor recycling. Evidence for the latter was obtained using lysosomotropic agents which blocked degradation but not binding and internalization of ligand and caused the intracellular accumulation of receptor. By comparing the relationship between receptor occupancy and biologic response induction, two activation mechanisms became apparent. Induction of certain functions, such as H2O2 secretion, appeared to require only a single round of receptor occupancy. However, induction of more complex functions such as nonspecific tumoricidal activity appeared to require three to four rounds of receptor occupancy. These results thus support the concept that IFN-gamma internalization and receptor recycling are essential in the induction of nonspecific tumoricidal activity by macrophages.
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PMID:Internalization and degradation of receptor-bound interferon-gamma by murine macrophages. Demonstration of receptor recycling. 295 10

MA158.2, a rat monoclonal antibody with binding specificity for cells of the monocyte-macrophage lineage, reacts with an antigen (158.2) whose expression is enhanced on mononuclear cells activated to the tumoricidal phenotype by treatment with lymphokine supernatant containing macrophage activating factor (MAF). The functional relevance of enhanced expression of this antigen has been examined in mouse peritoneal macrophages treated with a variety of immunomodulatory agents and assayed for augmented macrophage-mediated defense reactions, including O-2 production, microbicidal, and tumoricidal activity. An interferon-gamma (IFN-gamma) preparation produced by recombinant DNA technology induced a dose-dependent increase in expression of the 158.2 antigen in inflammatory macrophages which was accompanied by acquisition of microbicidal activity against Listeria monocytogenes. However, these cells did not express tumoricidal activity and induction of this property required concomitant exposure to lipopolysaccharide (LPS). Similar results were obtained using macrophages elicited with pyran copolymer. Exposure to LPS alone induced enhanced expression of antigen 158.2 but did not elicit microbicidal activity. Macrophages challenged with IFN-alpha, IFN-beta, MDP, and bestatin did not exhibit increased 158.2 and also failed to acquire tumoricidal activity when treated concomitantly with LPS. Collectively, these data indicate that the MA 158.2 antibody recognizes an antigen expressed by macrophage populations displaying the so-called primed phenotype in which microbicidal activity is expressed but in which induction of tumoricidal activity requires the addition of a second signal such as LPS.
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PMID:Induction by immunomodulatory agents of a macrophage antigen recognized by monoclonal antibody 158.2 and correlation with macrophage function. 301 25

Viral particles of a neurotropic murine hepatitis virus (JHM) and various substances known to have immunoregulatory effects, including bacterial lipopolysaccharide (LPS) and synthetic adjuvant peptide (muramyl dipeptide) (AP), were tested for their ability to induce Ia antigen expression on Lewis rat astrocytes in vitro. JHM virus, LPS and AP are all capable of inducing Ia molecules on astrocytes, however, in a pattern and kinetics distinct from recombinant rat gamma interferon (gamma-IFN). Whereas gamma-IFN induced Ia expression on astrocytes and all macrophages after 48 h treatment, JHM virus, LPS and AP required 4-7 days for maximal induction of Ia on astrocytes, but had little to no effect on the macrophage population. This indicates that astrocytes are uniquely reactive to components derived from infectious agents and that these components are immunoregulatory with respect to Ia expression on astrocytes. We have also attempted to determine possible mechanisms by which these agents induce astrocyte Ia and show that phorbol myristate acetate and Ca2+ ionophore A23187 have similar effects. These findings suggest that infectious agents may directly stimulate antigen presenting functions of astrocytes in the brain through gamma-IFN-independent mechanisms.
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PMID:Analysis of Ia induction on Lewis rat astrocytes in vitro by virus particles and bacterial adjuvants. 302 54


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