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)

1. Peroxynitrite, a cytotoxic oxidant formed from the reaction of nitric oxide (NO) and superoxide is a mediator of cellular injury in ischaemia/reperfusion injury, shock and inflammation. Here we investigated whether L-buthionine-(S,R)-sulphoximine (BSO), an inhibitor of gamma-glutamylcysteine synthetase, alters endothelial and vascular smooth muscle injury in response to peroxynitrite in vitro and during endotoxic shock in vivo. 2. In human umbilical vein endothelial cells and in rat aortic smooth muscle cells, BSO (1 mM, for 24 h) enhanced, whereas glutathione (3 mM) or glutathione ethyl ester (3 mM) attenuated the peroxynitrite (100-1000 microM)-induced suppression of mitochondrial respiration (measured by the conversion of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) to formazan), formation of nitrotyrosine (detected by Western blotting), protein oxidation (measured by detection of 2,4 dinitrophenylhydrazine-reactive carbonyls), and DNA single strand breakage and activation of the nuclear enzyme poly (ADP-ribose) synthetase (PARS) (measured by the incorporation of radiolabelled NAD+ into nuclear proteins and by the alkaline unwinding assay, respectively). Glutathione ethyl ester treatment reduced the BSO-induced enhancement of peroxynitrite-induced cytotoxicity. 3. In rat isolated thoracic aortic rings, BSO treatment (in vivo, at 1 g kg(-1) intraperitoneally (i.p.) for 24 h) enhanced, whereas pretreatment with glutathione (in vitro, 3 mM) attenuated the peroxynitrite-induced reduction of the contractions to noradrenaline, and the peroxynitrite-induced impairment of the endothelium-dependent relaxations to acetylcholine. 4. In BSO-pretreated rats, treatment with bacterial lipopolysaccharide (LPS, 15 mg kg(-1), i.p., for 6 h) caused a more pronounced vascular hyporeactivity and endothelial dysfunction ex vivo. BSO pretreatment also increased the degree of nitrotyrosine staining (detected by imunohistochemistry) in the aorta after LPS treatment. 5. In conclusion, our results demonstrate that L-buthionine-(S,R)-sulphoximine, an inhibitor of gamma-glutamylcysteine synthetase enhances peroxynitrite- and endotoxic shock-induced vascular failure. Based on these findings, we suggest that endogenous glutathione plays an important protective role against peroxynitrite- and LPS-induced vascular injury.
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PMID:Effect of L-buthionine-(S,R)-sulphoximine, an inhibitor of gamma-glutamylcysteine synthetase on peroxynitrite- and endotoxic shock-induced vascular failure. 950 94

Numerous studies suggest that tributyltin (TBT) is a potent immunotoxicant in nontarget organisms with lymphoid atrophy being a hallmark response. Two of the most common formulations of TBT are bis (tri-n-butyl)-tin oxide (TBTO) and tri-n-butyl-tin chloride (TBTCl). Most of studies investigating TBT-related immunotoxicity have used relatively high doses of both compounds, but little is known about the effects of very low doses. In addition, no studies have directly compared the effects of both formulations on immune function(s). We exposed female B6C3F1 mice to a single dose of TBTO or TBTCl at 0.3, 3.0, 30 mM/kg or corn oil as a carrier control. Forty-eight h later mice received a 4% solution of thioglycolate intraperitoneally to elicit peritoneal macrophages. Ninety-six h later macrophages were harvested and stimulated with a mixture of gamma-interferon (IFN-gamma) and lipopolysaccharide (LPS). Nitric oxide (NO), tumor necrosis factor-alpha (TNF-alpha), transforming growth factor beta-1 (TGF-beta1), and phorbol ester-stimulated oxidative burst activity were then measured. Nitric oxide and TNF-alpha production were significantly elevated in the 0.3 and 3.0 mM TBTO/kg-treated groups but not in those treated by TBTCl. Background TNF-alpha production (without stimulation) was also elevated at these two doses but suppressed in TBTCl-treated animals. Oxidative burst activity was elevated at 0.3 mM TBTO/kg but not by TBTCl. TGF-beta1 production was not altered by either treatment, nor were body wts and organ-body wt ratios. To further evaluate the difference between the effects of TBTO and TBTCl on macrophage function, the in vitro toxicity of the two was determined using elicited peritoneal macrophages from untreated mice. Following a 24-h exposure to increasing concentrations of TBTO or TBTCl, functional viability was evaluated using the MTT assay. There were no differences between the two compounds in terms of treatment-related viability except that at the very highest concentrations (10(-6) M) TBTO was more toxic than TBTCl.
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PMID:Macrophage secretory function is enhanced by low doses of tributyltin-oxide (TBTO), but not tributyltin-chloride (TBTCl). 950 67

Recent studies suggest lipopolysaccharide (LPS) mediated cell death as underlying mechanism of hyporesponsiveness and dysfunction of macrophages in the late phase of septic shock. In the present study LPS (0.001 - 30 microg/ml) caused a concentration-dependent toxicity in the macrophage cell line (J774.1A) within 24 h. The toxicity induced by LPS (1 microg/ml) was completely inhibited by the serine protease inhibitors, N-alpha-tosyl-L-phenylalanine chloromethyl ketone (TPCK) and N-alpha-tosyl-L-lysine chloromethyl ketone (TLCK) as measured by the mitochondrial-dependent oxidation of 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromid (MTT) to formazan. These inhibitors antagonize the activation of nuclear transcription factor-kappaB (NF-kappaB) indirectly by inhibiting I kappaB alpha-protease. SN50, a direct inhibitor of NF-kappaB translocation into the nucleus also protected macrophages from LPS-mediated toxicity. We conclude from these data that the early phase signal transduction pathway leading to LPS-mediated cytotoxicity in macrophages involves the activation of NF-kappaB. Thus, I kappaB alpha-protease inhibitors might serve as therapeutical agents to maintain macrophage viability during sepsis and to prevent sepsis-induced immune dysfunction.
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PMID:Protease inhibitors protect macrophages from lipopolysaccharide-induced cytotoxicity: possible role for NF-kappaB. 951 10

1. Microglial cells represent the first line of defence in the brain against infection and damage. However, under conditions of chronic inflammation and neurodegeneration, excessive activation of microglia can contribute to the neurodegenerative process by releasing a cornucopia of potentially cytotoxic substances including the cytotoxic free radical nitric oxide (NO). Although the cell signalling events implicated in NO formation in peripheral macrophages are well defined, events occurring in the phenotypically homologous cerebral microglial cell are not yet fully characterized. 2. In the present study, a cloned murine microglial cell line (N9), stimulated with combined lipopolysaccharide/interferon-gamma (LPS/IFN) incubation, was shown to produce a significant increase in NO formation, as measured by medium nitrite levels, during 8-72 h exposure. 3. LPS/IFN-stimulated NO production was partially inhibited with the nitric oxide synthase (NOS) competitive antagonists; N(omega)-nitro-L-arginine methyl ester and N(omega)-nitro-L-arginine. The ability of the selective inducible (iNOS) inhibitor, aminoguanidine, but not the selective 'neuronal-type' constitutive (cNOS) inhibitor 7-nitroindazole, to inhibit NO production suggested a primary role of iNOS in this response and was confirmed by immunolabelling of activated cells with a specific iNOS antibody. 4. A series of tyrosine kinase inhibitors, herbimycin A, genestein, tyrphostins, AG-126, AG-556 and the tyrosine phosphatase inhibitors, sodium orthovanadate and phenylarsine oxide, significantly attenuated LPS/IFN-mediated NO production. The serine/threonine kinase inhibitors, staursporine (protein kinase C), H-9 (cyclic GMP/cyclic AMP-dependent kinase) or serine/threonine phosphatase inhibitors, cyclosporin A (phosphatase 2B) and okadaic acid (phosphatase 1/2A), reduced NO formation by an apparent cytostatic mechanism, as determined by cellular reduction of 3-(4,5-dimethylthiazol-2-yi)-2,5-diphenyl-tetrazolium bromide (MTT). 5. The present results suggest that the co-ordinated activation of protein tyrosine kinases/phosphatases, and proximal signalling events implicating the interplay between serine-threonine kinases/phosphatases, is intricately linked with inflammatory mediated mechanisms of iNOS activation in microglial cells by regulating the activation of the transcription factor NFkappaB.
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PMID:Suppression of nitric oxide formation by tyrosine kinase inhibitors in murine N9 microglia. 953 16

Characterization of how vomitoxin (VT) and other trichothecenes affect macrophage regulatory and effector function may contribute to improved understanding of mechanisms by which these mycotoxins impact the immune system. The RAW 264.7 murine cell line was used as a macrophage model to assess effects of the VT on proliferation and the production of nitric oxide (NO), hydrogen peroxide (H2O2) and cytokines. Using the MTT cleavage assay, VT at concentrations of 50 ng/ml or higher was found to significantly decrease proliferation and viability of RAW 264.7 cells without stimulation or with stimulation by lipopolysaccharide (LPS) or interferon (IFN)-gamma. In the absence of an activation agent, VT (25-250 ng/ml) had negligible effects on the production of NO, H2O2, and cytokines. Upon activation with LPS at concentrations of 10 to 100 ng/ml, VT at 25-100 ng/ml markedly enhanced production of H2O2 but was inhibitory at 250 ng/ml. VT enhancement of H2O2 production was observed as early as 12 h after LPS stimulation. When IFN-gamma was used as the stimulant, VT (25-250 ng/ml) delayed peak H2O2 production. VT (25-250 ng/ml) also markedly decreased NO production in cells activated with LPS or IFN-gamma. Interestingly, VT superinduced TNF-alpha and IL-6 production in LPS-stimulated cells and also elevated TNF-alpha in IFN-gamma stimulated cells. These results suggest that VT can selectively and concurrently upregulate or downregulate critical functions associated with activated macrophages.
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PMID:Modulation of nitric oxide, hydrogen peroxide and cytokine production in a clonal macrophage model by the trichothecene vomitoxin (deoxynivalenol). 957 Mar 33

Here we investigate the effects of tetracycline base and of a semi-synthetic tetracycline derivative, doxycycline, on the induction of inducible nitric oxide synthase and, hence, on the production of nitric oxide (NO) by lipopolysaccharide in J774 macrophage cultured in vitro. The treatment of J774 line with tetracycline base (6.25-250 microM) or doxycycline (5-50 microM) dose-dependently decreased the lipopolysaccharide-stimulated (1 microg/ml) inducible NO synthase activity and, consequently, nitrite formation. For instance, the inhibition was 70% for tetracycline base at 250 microM and 68% for doxycycline at 50 microM. The inhibitory effect of tetracyclines was due neither to a reduction in the viability of the cells, studied as colorimetric 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide (MTT) reduction assay, nor to an indiscriminate inhibition of total protein synthesis, but to a specific decrease in inducible NO synthase protein content in the cells, as attested by the significant reduction of the expression of inducible NO synthase, assayed by sodium-dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot. However, no effect of tetracyclines on inducible NO synthase mRNA accumulation could be demonstrated in lipopolysaccharide-stimulated macrophage line, suggesting that the inhibitory effect of tetracyclines on NO synthesis involves post-transcriptional events. The reduction in lipopolysaccharide-stimulated nitrite accumulation produced by tetracyclines was significantly less when they were applied 6 h after lipopolysaccharide and absent 12 h after lipopolysaccharide, indicating that tetracyclines modify an early event in inducible NO synthase activation operating after mRNA transcription. The findings presented in this study indicate that the modulation of NO synthesis is another possible pathway by which tetracyclines may function as anti-inflammatory compounds.
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PMID:Tetracycline inhibits the nitric oxide synthase activity induced by endotoxin in cultured murine macrophages. 965 71

Antibiotics have previously been shown to have immunomodulatory effects. We examined the effect of the broad-spectrum fluoroquinoline antibiotic trovafloxacin on cytokine synthesis by monocytes obtained from healthy human volunteers and stimulated with either lipopolysaccharide or gram-positive cells (heat-killed Staphylococcus aureus [Pansorbin]). Trovafloxacin levels achievable in humans suppressed in vitro synthesis of each of the cytokines analyzed, viz., interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-6, IL-10, granulocyte-macrophage colony-stimulating factor, and tumor necrosis factor alpha. This effect was not due to direct effects of the drug on cellular viability; at these concentrations, trovafloxacin did not have demonstrable cytotoxicity for the monocytes, as determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. Although similar patterns of suppression of cytokine synthesis were observed in samples obtained from the same volunteers on different days, there were significant day-to-day variations. These results reveal that trovafloxacin possesses significant immunomodulatory activity in vitro and suggest that suppression of acute-phase inflammatory responses may occur in vivo, elicited through trovafloxacin's effect on cytokine synthesis by human monocytes.
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PMID:Effect of trovafloxacin on production of cytokines by human monocytes. 966 Oct 9

Immunomodulatory activities of constituents isolated from Hydrangeae Dulcis Folium and their related compounds on lymphocyte proliferation were investigated using splenocytes and lymph node cells. Thunberginol A (TA) significantly suppressed B lymphocyte proliferation stimulated by lipopolysaccharide (LPS) at 10(-5) M. However TA at a lower concentration (10(-6) M) and the other compounds, except hydrangenol and 3'-hydroxyhydrangeaic acid, tended to potentiate B lymphocytes proliferation (10(-5) M). On the other hand, thunberginol A significantly suppressed T lymphocyte proliferation stimulated by concanavalin A (Con A), but did not suppress phytohemagglutinin (PHA). Hydrocortisone and cyclosporin A strongly suppressed T lymphocyte proliferation induced by both Con A and PHA. These results suggest that thunberginol A acts on both B and T lymphocytes and may have a suppressive mechanism different from the known immunosuppressants. The cytotoxicity of TA for splenocytes seemed weaker than known immunosuppressants resulting from viability tests using MTT assay and the measurement of lactate dehydrogenase (LDH) released in the medium. Moreover, TA suppressed antigen-specific T lymphocyte proliferation in mice lymph node cells immunized with keyhole limpet hemocyanin (KLH). Thus, these findings show that TA has a suppressive effect on lymphocyte activation, and this inhibitory effect of TA seems to contribute to its suppressive effect on type IV allergies.
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PMID:Development of bioactive functions in Hydrangeae Dulcis Folium. VII. Immunomodulatory activities of thunberginol A and related compounds on lymphocyte proliferation. 974 47

We determined the MICs of ampicillin, ciprofloxacin, erythromycin, imipenem, and rifampin for two clinical isolates of Legionella pneumophila serogroup 1 by 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) reduction assay and by quantitative culture. To test the influence of subinhibitory concentrations (sub-MICs) of antimicrobial agents on Legionella uptake into Acanthamoeba castellanii and U937 macrophage-like cells, both strains were pretreated with 0.25 MICs of the antibiotics for 24 h. In comparison to that for the untreated control, subinhibitory concentrations of antibiotics significantly reduced Legionella uptake into the host cells. Measurement of the binding of monoclonal antibodies against several Legionella antigens by enzyme-linked immunoassays indicated that sub-MIC antibiotic treatment reduced the expression of the macrophage infectivity potentiator protein (Mip), the Hsp 60 protein, the outer membrane protein (OmpM), an as-yet-uncharacterized protein of 55 kDa, and a few lipopolysaccharide (LPS) epitopes. In contrast, the expression of some LPS epitopes recognized by monoclonal antibodies 8/5 and 30/4 as well as a 45-kDa protein, a 58-kDa protein, and the major outer membrane protein (OmpS) remained unaffected.
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PMID:Subinhibitory concentrations of antimicrobial agents reduce the uptake of Legionella pneumophila into Acanthamoeba castellanii and U937 cells by altering the expression of virulence-associated antigens. 979 18

The mechanisms used by Haemophilus somnus to survive and multiply within bovine mononuclear phagocytes are not fully understood. In order to study the interaction between bovine mononuclear phagocytes and H. somnus, a colorimetric assay using 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenylItetrazolium bromide (MTT) was developed to assess the survival of H. somnus within cultured bovine blood monocytes (BBM). Using this system, it was found that H. somnus was able to survive within BMM in vitro, and the kinetics of its survival were similar to that seen in BBM isolated from experimentally infected cattle. Using ultrastructural studies, it was possible to demonstrate the survival of H. somnus in freshly isolated bovine mononuclear phagocytes in membrane-bound vacuoles. To determine if activation of macrophage function would result in elimination of intracellular H. somnus, BBM were treated with E. coli lipopolysaccharide (LPS) or recombinant bovine (rBo) cytokines, interferon-gamma (IFN-gamma), granulocyte macrophage colony stimulating factor (GM-CSF), tumour necrosis factor-alpha (TNF-alpha) or interleukin-1beta (IL-1beta). Treatment of BBM with rBoIFN-gamma, rBoGM-CSF or E. coli LPS resulted in decreased intracellular survival of H. somnus at 18 and 48 h, whereas BBM treated with rBoTNF-alpha or rBoIL-1beta had reduced intracellular survival of H. somnus only at 18 h. However, none of these treatments resulted in complete elimination of the intracellular bacteria. The ability of H. somnus to survive and multiply in both freshly isolated and cytokine-treated cultured BBM demonstrated the capability of H. somnus to escape from macrophage killing mechanisms. This capability may play a role in the dissemination of H. somnus infection in the body.
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PMID:Intracellular survival of Haemophilus somnus in bovine blood monocytes and alveolar macrophages. 987 52


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