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)

It has been proposed that TNF-alpha mediates TCDD-induced toxicity. TCDD induces a chloracne-like response in the skin of hairless HRS/J mice but not in congenic haired animals. Using an ELISA, we measured TNF-alpha levels in the skin of TCDD-treated haired and hairless HRS/J mice to test the hypothesis that TNF-alpha mediates the cutaneous toxicity of TCDD. TNF-alpha levels in the skin of haired mice were at or below minimal detectable levels and were unchanged by TCDD exposure. In contrast, TNF-alpha levels were significantly higher in the skin of hairless mice after TCDD exposure. The bulk of the induced TNF-alpha was present in the dermis, although detectable amounts were present in the epidermis. To determine if murine skin cells were producing TNF-alpha in direct response to TCDD, cultures of neonatal epidermal keratinocytes and dermal fibroblasts were treated with varying biologically active doses of TCDD or vehicle (DMSO) or with lipopolysaccharide (LPS) as a positive control. Within 24 hr of exposure to LPS, TNF-alpha levels were increased in the culture media of all cells tested. In contrast, TCDD treatment (10(-11) M to 10(-7) M) failed to induce detectable TNF-alpha release from either fibroblasts or keratinocytes over a comparable time frame or when measured for up to 6 days following exposure. The failure of TCDD to stimulate TNF-alpha production by keratinocytes or fibroblasts suggests that the rise in dermal TNF-alpha levels seen in vivo is unlikely to be a primary component of the mechanism of toxicity. We suggest that the source of the dermal TNF-alpha in TCDD-treated hairless mouse skin is probably component cells of the inflammatory response.
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PMID:Influence of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on TNF-alpha levels in the skin of congenic haired and hairless mice. 797 84

NMR and crystallography have been used to study antigen conformational changes that occur in a trisaccharide-Fab complex in solution and in the solid state. NOE buildup rates from transferred NOE experiments show that the antigenic determinant of a Salmonella lipopolysaccharide, represented by the trisaccharide methyl glycoside alpha-D-Galp(1-->2 [alpha-D-Abep(1-->3)]- alpha-D-Manp1-->OMe (1), undergoes a protein-induced conformational shift about the Gal-->Man glycosidic linkage when it is bound by a monoclonal antibody in aqueous solution. The same trisaccharide was crystallized with Fab, and a solved structure at 2.1-A resolution revealed that the conformation of the trisaccharide ligand was similar to that seen in a dodesaccharide-Fab complex [Cygler et al. (1991) Science 253, 442-445), where the Gal-Man linkage also experienced a similar conformational shift. Distance constraints derived from the TRNOE buildup curves are consistent with two bound trisaccharide conformations, one of which correlates with the ligand conformation of the crystalline Fab-trisaccharide complex. In this bound conformation, short interatomic distances between Abe O-2 and Gal O-2 permit an oligosaccharide intramolecular hydrogen bond. Despite its relatively low energy, a preponderance of this conformer could not be detected in aqueous or DMSO solutions of free trisaccharide by either 1H or 13C NMR experiments. In DMSO, a different intramolecular hydrogen bond between Abe O-2 and Man O-4 was observed due to a solvent-induced shift in the conformational equilibria (relative to aqueous solution). Molecular modeling of the trisaccharide in the binding site and as the free ligand suggested that the protein imposes an induced fit on the antigen, primarily resulting in a shift of the Gal-Man phi torsional angle. This reduces the interproton separation between Abe H-3 and Gal H-1 with a marked increase in the intensity of the previously weak NOEs between the protons of the noncovalently linked galactose and abequose residues. The impact of the conformational shift on gross trisaccharide topology is sufficiently small that binding modes inferred from functional group replacements are not impaired.
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PMID:Solution structure of a trisaccharide-antibody complex: comparison of NMR measurements with a crystal structure. 817 93

The two apparent form of the endotoxin-sensitive Factor C which were found to exist in the amoebocytes of horseshoe crabs have been separately purified to homogeneity from the lysate of the South-East Asian species, Carcinoscorpius rotundicauda. Both forms are serine proteinase zymogens having an apparent molecular mass of 132 kDa. By reducing SDS-PAGE, one was shown to consist of a single polypeptide while the other has a heavy chain (80 kDa) and a light chain (52 kDa) bridged by disulfide linkage(s). Both zymogen forms have endotoxin (lipopolysaccharide) receptors to which endotoxin binds to activate their catalytic sites. However, single-chain Factor C appears to have higher-affinity endotoxin-binding sites which are competitively but reversibly occupied by DMSO when the latter was added during its purification. Another salient difference between the two forms of Factor C is exhibited in their manner of activation by endotoxin. While double-chain Factor C appears similar to that of Tachypleus tridentatus, single-chain Factor C did not undergo any proteolytic cleavage upon activation. This conformational transition of zymogen activation suggests an alternative reversible pathway of endotoxin activation for the single-chain Factor C.
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PMID:Two forms of factor C from the amoebocytes of Carcinoscorpius rotundicauda: purification and characterisation. 837 18

The role of a 150-kD SR-cyclophilin (NK-TR1) in monocyte differentiation was investigated. Using an antipeptide monoclonal antibody, we have detected NK-TR1 in human peripheral blood monocytes and HL-60 cells. Unstimulated monocytes showed a low intracellular level of NK-TR1 protein that increased over 3 days of lipopolysaccharide + interferon-gamma treatment, consistent with the kinetics of monocyte differentiation. Normal HL-60 cells also had a low level of NK-TR1 protein, and exposure to 1.25% dimethyl sulfoxide (DMSO) resulted in a marked transient increase in expression that returned to basal levels before the development of granulocyte differentiation-associated biochemical changes. Phorbol myristate acetate, a promoter of monocytic differentiation in HL-60 cells, also caused a significant increase in NK-TR1 over basal levels. Transfection of a vector expressing NK-TR1 antisense RNA into HL-60 cells suppressed DMSO-mediated growth arrest. In addition, the development of a more mature phenotype, as measured by expression of CD16, and the ability to reduce nitroblue tetrazoleum dye was inhibited in transfectants when compared with controls. These results are consistent with the hypothesis that the NK-TR1 gene product is required for the progression towards a mature differentiated phenotype.
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PMID:Association of the expression of an SR-cyclophilin with myeloid cell differentiation. 863 Mar 87

The effects of urban air and diesel particles on inflammatory cytokine gene expression, tumor necrosis factor alpha (TNF-alpha) in particular, were studied in rat alveolar macrophages. TNF-alpha, interleukin (IL)-1, IL-6, cytokine-induced neutrophil chemoattractant (CINC), and macrophage inflammatory protein (MIP)-2 gene expression and TNF-alpha secretion were increased in cells treated with 50 to 200 micrograms/mL of urban air particles in a concentration-related manner. There was no cytokine induction by diesel particles at any of the concentrations tested. Cytokine expression was not related to reactive oxygen species since antioxidants, such as catalase, TMTU, or DMSO, had no effect on TNF-alpha secretion. However, cytokine induction by urban air particles was completely prevented by polymyxin B, an antibiotic capable of neutralizing bacterial lipopolysaccharide (LPS) activities. Furthermore, LPS was detected on the urban air particles, but not on diesel particle. These results suggest that activation of cytokine gene expression and secretion in rat alveolar macrophages by urban air particles is due to the presence of endotoxin on the particles.
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PMID:Role of endotoxin in tumor necrosis factor alpha expression from alveolar macrophages treated with urban air particles. 888 60

Generation of reactive oxygen species (ROS) is a common event in the pathogenesis of acute lung injury. Endothelial cells may be both a target and a source of the ROS. Exposure of bovine pulmonary endothelial cells (BPAEC) to lipopolysaccharide (LPS) has been shown to result in intracellular generation of both ROS and the antioxidant enzyme, mangano superoxide dismutase (MnSOD). The present study investigates whether alterations in intracellular oxidant state affect LPS-stimulated cytotoxicity and induction of MnSOD mRNA. BPAEC were pretreated with either the free radical scavenger, dimethylsulfoxide (DMSO), the xanthine oxidase inhibitor, allopurinol, or N-acetylcysteine (a cysteine derivate capable of increasing glutathione stores) prior to exposure to LPS (0.1 microgram/ml) for either 4, 8 or 18 hours. We found that pretreatment of BPAEC with DMSO blocked both LPS-induced cytotoxicity and induction of the MnSOD gene. Nuclear run-off experiments demonstrated that LPS-stimulated induction of the MnSOD mRNA occurred at the transcriptional level and that DMSO blocked this event. Pretreatment with allopurinol also prevented the cytotoxicity associated with LPS but, in contrast to DMSO, did not alter induction of MnSOD mRNA. N-acetylcysteine did not affect the LPS-stimulated cytotoxicity but resulted in an early and transient reduction in induction of the MnSOD gene. We conclude that LPS stimulates generation of intracellular ROS that regulate induction of the MnSOD gene at the transcriptional level further, we conclude that LPS-stimulated cytotoxicity involves both the xanthine oxidase pathway and perhaps intracellular generation of hydroxyl radicals. The difference in the protective effect between DMSO, NAC and allopurinol suggest that upregulation of the MnSOD gene does not contribute to LPS-induced cytotoxicity.
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PMID:Effect of antioxidants on lipopolysaccharide-stimulated induction of mangano superoxide dismutase mRNA in bovine pulmonary artery endothelial cells. 890

While the regulation of nitric oxide (NO) by inflammatory cytokines or lipopolysaccharide (LPS) has received considerable attention, NO modulation of cytokine expression has yet to be fully explored. The NO synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), inhibited interleukin (IL)-8 and IL-6 production in LPS-stimulated human whole blood in a dose-dependent manner. In the presence of 1 microgram/mL LPS, L-NAME blocked IL-8 release (72 +/- 4% inhibition at 20 mM (mean +/- SEM, p < .05)) 24 h post-LPS without affecting cellular viability. IL-6 production was significantly inhibited only with the highest dose of L-NAME used. L-NAME inhibition of IL-8 production was also observed at the mRNA level. Conversely, direct exposure of whole blood to NO with the spontaneous NO liberator DETA NONOate caused a dose-dependent stimulation of IL-8, but had no effect on IL-6 release. IL-8 concentrations rose from 8.3 +/- 1.9 ng/mL at 24 h to 31.7 +/- 7.6 ng/mL at 72 h with a single stimulation of 10 mM DETA NONOate. The hydroxyl radical scavenger dimethyl sulfoxide (DMSO) prevented the DETA NONOate induction of IL-8, suggesting the participation of the hydroxyl radical in the NO-induced IL-8 production. These results provide important evidence substantiating a role for NO as a regulator of cytokine expression.
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PMID:Nitric oxide regulation of interleukin-8 gene expression. 898 33

Nitric oxide (NO) synthase inhibitors, such as NG-nitro-L-arginine methyl ester (L-NAME), have been shown to attenuate endotoxin-induced uveitis (EIU) but they could increase leukocyte adhesion to the vascular endothelium. We hypothesize that a concomitant treatment with the 5-lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA) in 50% dimethylsulfoxide (DMSO, a hydroxyl radical scavenger) could improve the anti-inflammatory activity of L-NAME. EIU was induced in albino rabbits by intravitreal injection of 100 ng lipopolysaccharide. Animals were treated with multiple intraperitoneal injections of 50% DMSO in phosphate-buffered saline (PBS), NDGA (10 mg/kg) in 50% DMSO, L-NAME (50 mg/ kg) in PBS, or the combination NDGA+L-NAME. Uveitis was assessed by slit lamp examination, protein levels in aqueous humor, and myeloperoxidase (MPO) activity in the iris/ciliary body 6 h after induction. Nitrite, leukotriene B4 (LTB4), prostaglandin E2 (PGE2), platelet-activating factor (PAF) and interleukin-1 beta (IL-1 beta) levels in aqueous humor were also determined. NDGA or L-NAME alone did not show a significant reduction of uveitis intensity, although a significant decrease in MPO or in proteins was found, respectively. The combination NDGA+L-NAME significantly reduced the uveitis intensity, MPO in the iris/ciliary body, and the levels of nitrites, LTB4, PGE2, and PAF in aqueous humor. IL-1 beta levels were lower than the detection limit of the radioimmunoassay in all treatment groups. We conclude that concomitant treatment with NDGA in DMSO improves the anti-inflammatory activity of L-NAME during the early phase of EIU, suggesting that the inhibition of NO synthesis could enhance leukocyte infiltration and the release of oxygen free radicals.
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PMID:Concomitant treatment with a 5-lipoxygenase inhibitor improves the anti-inflammatory effect of the inhibition of nitric oxide synthase during the early phase of endotoxin-induced uveitis in the rabbit. 926 46

Treatment and pretreatment of hepatocytes with 2% dimethyl sulfoxide (DMSO) inhibited lipopolysaccharide and cytokine mixture (LPS/CM)-mediated NO synthesis in hepatocytes without any obvious effects on cell viability. DMSO at concentrations of 0.5-4% stimulated DNA replication and increased albumin secretion in LPS/CM-treated hepatocytes. Genisein, a inhibitor of protein tyrosine kinase (PTK), inhibited LPS/CM-mediated NO synthesis in hepatocytes. These results suggest that PTK is critical for hepatocyte NO synthesis, and DMSO-inhibited NO synthesis may be associated with prevention of LPS/CM-induced PTK activation in hepatocytes.
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PMID:Inhibition of lipopolysaccharide and cytokine mixture-mediated hepatocyte nitric oxide synthesis by dimethyl sulfoxide. 934 62

Heme oxygenase-1 (HO-1) is a stress-response protein, the expression of which is transcriptionally regulated by agents that cause oxidative stress. We have previously shown that lipopolysaccharide (LPS)-induced HO-1 gene transcription in RAW 264.7 macrophage cells is mediated by a distal enhancer called SX2, located 4 kb upstream from the HO-1 transcription initiation site (Am. J. Respir. Cell Mol. Biol. 1995;13:387-398). We have recently identified a second distal enhancer, called AB1, located 6 kb upstream from the SX2 distal enhancer (J. Biol. Chem. 1995;270:11977-11984). Here we report the extension of our studies to investigate whether the AB1 distal enhancer and/or other potential regulatory elements in the entire 5' distal flanking sequences (11-kb region) of the HO-1 gene may also mediate HO-1 gene transcription in response to LPS. Using deletional analysis, we found that the AB1 enhancer also mediates LPS-induced HO-1 gene transcription. Mutational analysis of the AB1 enhancer and electrophoretic-mobility-shift assays of nuclear extracts from LPS-treated cells further demonstrated that the transcription factor activator protein-1 (AP-1) is critical for AB1-mediated HO-1 gene activation by LPS. We also found increased expression of AP-1 family members c-fos and c-jun by Northern blot analyses after treatment with LPS. Further, we observed that LPS-treated RAW 264.7 cells produced high levels of reactive oxygen intermediates (ROI) as measured through flow-cytometric analysis of dichlorofluoroscein (DCF)-stained cells. Treatment of cells with the antioxidants N-acetyl-L-cysteine (NAC) and dimethyl sulfoxide (DMSO) not only blunts LPS-induced production of ROI, but also significantly attenuates LPS-induced HO-1 messenger RNA (mRNA) expression and gene transcription. Taken together, these data suggest that LPS regulates HO-1 gene transcription in part by inducing the production of ROI, which initiate signal-transduction pathway(s) leading to the activation of AP-1-dependent HO-1 gene transcription.
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PMID:Transcriptional activation of the HO-1 gene by lipopolysaccharide is mediated by 5' distal enhancers: role of reactive oxygen intermediates and AP-1. 947 10


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