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)

The present study investigated the mechanisms involved in the increased 5-hydroxytryptamine (5-HT) vasoconstriction observed in rat middle cerebral arteries exposed in vitro to lipopolysaccharide (LPS, 10 microg x ml-1) for 1-5 h. Functional, immunohistochemical and Western blot analysis and superoxide anion measurements by ethidium fluorescence were performed. LPS exposure increased 5-HT (10 microm) vasoconstriction only during the first 4 h. In contrast to control tissue, indomethacin (10 microm), the COX-2 inhibitor NS 398 (10 microm), the TXA2/PGH2 receptor antagonist SQ 29548 (1 microm) and the TXA2 synthase inhibitor furegrelate (1 microm) reduced 5-HT contraction of LPS-treated arteries from hour one. The iNOS inhibitor aminoguanidine (0.1 mm) increased 5-HT contraction from hour three of LPS incubation. The superoxide anion scavenger superoxide dismutase (SOD, 100 U ml-1) and the H2O2 scavenger catalase (1000 U ml-1), as well as the respective inhibitors of NAD(P)H oxidase and xanthine oxidase, apocynin (0.3 mm) and allopurinol (0.3 mm), reduced 5-HT contraction after LPS incubation. LPS induced an increase in superoxide anion levels that was abolished by PEG-SOD. Subthreshold concentrations of the TXA2 analogue U 46619, xanthine/xanthine oxidase and H2O2 potentiated, whereas those of sodium nitroprusside inhibited, the 5-HT contraction. COX-2 expression was increased at 1 and 5 h of LPS incubation, while that of iNOS, Cu/Zn-SOD and Mn-SOD was only increased after 5 h. All the three vascular layers expressed COX-2 and Cu/Zn-SOD. iNOS expression was detected in the endothelium and adventitia after LPS. In conclusion, increased production of TXA2 from COX-2, superoxide anion and H2O2 enhanced vasoconstriction to 5-HT during the first few hours of LPS exposure; iNOS and SOD expression counteracted that increase at 5 h. These changes can contribute to the disturbance of cerebral blood flow in endotoxic shock.
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PMID:Mechanisms involved in the early increase of serotonin contraction evoked by endotoxin in rat middle cerebral arteries. 1453 51

This study was performed to investigate the role of reactive oxygen species and inducible nitric oxide (NO) synthase (iNOS) and cyclooxygenase-2 (COX-2) metabolites in the lipopolysaccharide effect on bradykinin-induced relaxation in middle cerebral arteries from normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHRs). LPS exposure (10 microg/ml for 1-5 h) reduced bradykinin relaxation; this effect appeared earlier and was greater in arteries from SHR than WKY rats. LPS also reduced the relaxation to the NO donor diethylamine (DEA)-NO; however, LPS modified neither the bradykinin relaxation after inhibiting NO synthesis with N(G)-monomethyl-L-arginine (0.1 mM) nor endothelial NOS expression. In arteries from WKY rats, the respective iNOS and COX-2 inhibitors aminoguanidine (0.1 mM) and NS-398 (10 microM) and the superoxide anion scavenger SOD (100 U/ml) reduced the LPS effect on bradykinin relaxation; however, the thromboxane A(2) (TxA(2))PGH(2) receptor antagonist SQ-29548 (1 microM) and the H(2)O(2) scavenger catalase (1,000 U/ml) did not modify the LPS effect. In arteries from SHR, all of these drugs reduced the LPS effect. LPS exposure (5 h) increased superoxide anion levels in arteries from both strains and TxA(2) levels only in SHR. COX-2 expression rose to a similar level in arteries from both strains after 1 and 5 h of LPS incubation, whereas expression of Cu/Zn- and Mn-SOD only increased after 5 h. In conclusion, in segments from WKY rats, LPS reduced bradykinin-induced relaxation through increased production of NO (from iNOS) and superoxide anion. The greater LPS effect observed in arteries from SHR seems to be related to higher participation of reactive oxygen species and contractile prostanoids (probably TxA(2)).
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PMID:Hypertension alters role of iNOS, COX-2, and oxidative stress in bradykinin relaxation impairment after LPS in rat cerebral arteries. 1500 39

This study was carried out to elucidate whether the protective activity of (-)-epicatechin 3-O-gallate (ECg) against excessive peroxynitrite (ONOO(-)) production, is distinct from the activity of several well-known free radical inhibitors, the ONOO(-) inhibitors ebselen and uric acid, the superoxide anion (O(2)(-)) scavenger copper zinc superoxide dismutase (CuZnSOD) and the selective inducible nitric oxide synthase inhibitor L-N(6)-(1-iminoethyl)lysine hydrochloride (L-NIL). To generate ONOO(-), male Wistar rats (n = 6/group) were subjected to ischaemia-reperfusion process together with lipopolysaccharide (LPS) injection. Although ECg did not scavenge the ONOO(-) precursors nitric oxide (NO) and O(2)(-), it reduced the 3-nitrotyrosine level, a property similar to that of uric acid, but distinct from L-NIL. In addition, the elevation in myeloperoxidase activity was reversed by the administration of ECg, uric acid and SOD, but not by that of L-NIL. Furthermore, ECg was the more potent scavenger of the ONOO(-) decomposition product, the hydroxyl radical (*OH), than any other free radical inhibitor tested. The LPS plus ischaemia-reperfusion process resulted in renal dysfunction, estimated by measuring the parameters of renal function--serum urea nitrogen and creatinine levels. However, administration of ECg ameliorated renal dysfunction more than that of the other free radical inhibitors. Moreover, ECg reduced the excessive uric acid level, while the others did not, suggesting a property of ECg distinct from the others. Furthermore, proteinuria, which was demonstrated by the low- and high-molecular weight (LMW and HMW) protein bands of the sodium dodecyl sulfate-polyacrylamide gel electrophoresis pattern, caused by LPS plus ischaemia-reperfusion, was attenuated by administration of ECg and L-NIL, after which the HMW band intensities decreased and LMW protein bands were absent. This study indicates that, in an in-vivo model of ONOO(-) generation, ECg, L-NIL and uric acid exert stronger protective activity against ONOO(-)-induced oxidative damage than SOD and ebselen, and that the mechanism whereby ECg protects against ONOO(-) is distinct from that of L-NIL or uric acid.
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PMID:(-)-Epicatechin 3-O-gallate ameliorates the damages related to peroxynitrite production by mechanisms distinct from those of other free radical inhibitors. 1500 82

The phenomenon of endotoxin tolerance has been widely investigated, but to date, the molecular mechanisms of endotoxin tolerance remain to be resolved clearly. The discovery of the Toll-like receptor (TLR) family as the major receptors for lipopolysaccharide (LPS) and other bacterial products has prompted a resurgence of interest in endotoxin tolerance mechanisms. Changes of cell surface molecules, signaling proteins, pro-inflammatory and anti-inflammatory cytokines and other mediators have been examined. During tolerance expression of LPS-binding protein (LBP), CD14, myeloid differentiation protein-2 (MD-2) and TLR2 are unchanged or up-regulated, whereas TLR4 is transiently suppressed or unchanged. Proximal post-receptor signaling proteins that are altered in tolerance include augmented degradation of interleukin-1 receptor-associated kinase (IRAK), and decreased TLR4-myeloid differentiation factor 88 (MyD88) and IRAK-MyD88 association. Tolerance has also been shown to be associated with decreased Gi protein content and activity, decreased protein kinase C (PKC) activity, reduction in mitogen-activated protein kinase (MAP kinase) activity, and reduced activator protein-1 (AP-1) and nuclear factor kappa B (NF-kappaB) induced gene transactivation. However, not all signaling proteins and pathways are suppressed in tolerance and induction of specific anti-inflammatory proteins and signaling pathways may serve important counter inflammatory functions. The latter include induction of IRAK-M and suppressor of cytokine-signaling-1 (SOCS-1), phosphoinositide-3-kinase (PI3K) signaling, and increased or maintained expression of inhibitor-kappaB (IkappaB) isoforms. Also at the nuclear level, increase in the NF-kappaB subunit p50 homodimer expression and increased activation of peroxisome-proliferator-activated receptors-gamma (PPARgamma) have been linked to tolerance phenotype. Although there are species and cellular variations in manifestation of the LPS tolerant phenotype, it is clear that the tolerance phenomena have evolved as a complex orchestrated counter regulatory response to inflammation.
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PMID:Molecular mechanisms of endotoxin tolerance. 1511 98

Nuclear factor-kappaB (NF-kappaB) transcription factors are important in regulating the immune response and play critical roles in the pathogenesis of chronic inflammatory diseases and a variety of human cancers. Agents that target specific NF-kappaB dimers may serve as therapeutic agents for the prevention of pathogenic immune responses. We have selected monothiophosphate-modified aptamers, or "thioaptamers", to the NF-kappaB p50/RelA heterodimer using combinatorial selection techniques. We also utilized a "double sieve" or editing approach for the generation of thioaptamers with enhanced selectivity to the RelA/RelA homodimer. The thioaptamers from these selections and our previous selections on the p50/p50 and RelA/RelA homodimers all had unique sequences and bound tightly to the recombinant NF-kappaB dimers against which they were selected. The selected thioaptamers also appear to maintain their selectivity and specificity among other cellular proteins, because they have the ability to bind NF-kappaB proteins within nuclear extracts from lipopolysaccharide (LPS)-induced macrophages and B cells.
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PMID:Combinatorial selection and edited combinatorial selection of phosphorothioate aptamers targeting human nuclear factor-kappaB RelA/p50 and RelA/RelA. 1524 68

Antioxidants have been shown to be effective in attenuating acute lung injury. In this study, we determine the effects of various antioxidants by different mechanisms on the lipopolysaccharide (LPS)-induced changes. LPS was administered intravenously at a dose of 10 mg/kg to anesthetized rats. LPS induced a significant decrease in blood pressure (P < 0.01) and increased exhaled nitric oxide (NO) from 3.60+/-0.18 to 35.53+/-3.23 ppb (P < 0.01) during an observation period of 4 h. Plasma nitrate concentrations also increased from 0.61+/-0.06 to 1.54+/-0.22 micromol/l (P < 0.05). LPS-induced oxygen radical release from white blood cells isolated from rat peripheral blood also increased significantly (P < 0.001). After the experiment, the lung weight was obtained and lung tissues were taken for the determination of mRNA expression of inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta) and manganese superoxide dismutase (MnSOD). Histological examination of the lungs was also performed. In the control group injected with saline solution, mRNA expressions of iNOS, IL-1beta, TNF-alpha and MnSOD were absent. Four hours after LPS administration, mRNA expressions of iNOS, IL-1beta, and MnSOD were significantly enhanced, but TNF-alpha was not discernibly expressed. LPS also caused a twofold increase in lung weight. Pathological examination revealed endothelial cell damage and interstitial edema. Various antioxidants were given 1 h after LPS administration. These agents include SOD, catalase (CAT), SOD + CAT or vitamin C (ascorbic acid). These antioxidants effectively reversed the systemic hypotension, reduced the quantity of exhaled NO and plasma nitrate concentration, and prevented acute lung injury. Administration of various antioxidants also significantly attenuated LPS-induced oxygen radical release by rat white blood cells. LPS induced mRNA expressions of MnSOD and iNOS were significantly depressed by these antioxidants. However, only SOD + CAT and vitamin C inhibited the mRNA expression of IL-1beta. These results suggest that oxygen radicals are responsible for LPS-induced lung injury. Antioxidants can attenuate the lung injury by inhibiting mRNA expressions of iNOS and IL-1beta.
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PMID:Effects of various antioxidants on endotoxin-induced lung injury and gene expression: mRNA expressions of MnSOD, interleukin-1beta and iNOS. 1561 28

Arg-gingipain (Rgp) and Lys-gingipain (Kgp) are Porphyromonas gingivalis cysteine proteinases implicated as major virulence factors in pathologies of periodontitis. We purified a 660-kDa cell-associated gingipain complex existing as a homodimer of two catalytically active monomers which comprises their catalytic and adhesin domains. Electron microscopy revealed that the complex was composed of a globular particle with a 10-nm external diameter possessing one or two electron-dense hole-like structures. Two-dimensional gel electrophoresis and immunoblot analyses revealed the association of lipopolysaccharide (LPS) with the catalytic domains and a hemagglutinin domain, Hgp44, of Rgp and Kgp in the complex. The complex significantly degraded human type I collagen and elastin and strongly disrupted viability of human gingival fibroblasts and umbilical vein endotherial cells with an efficiency which was higher than that of the monomeric gingipains. The native complex produced only a small amount of nitrogen dioxide, tumor necrosis factor alpha, and interleukin-6 by macrophages, whereas the heat-denatured complex resulted in increased production. Inhibition of the proteolytic activities of the gingipain complex did not up-regulate the cytokine production, indicating that the functional domains in LPS are structurally masked by the complex proteins. These results indicate the importance of the complex in evasion of host defense mechanisms as well as in host tissue breakdown.
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PMID:A functional virulence complex composed of gingipains, adhesins, and lipopolysaccharide shows high affinity to host cells and matrix proteins and escapes recognition by host immune systems. 1566 30

The effect of Cu plate on the cellular function was investigated by two different methods: an extraction method (Method I) and a direct contact method (Method II). In Method I, the supernatant of the culture medium, which had been pre-incubated with Cu plate, was added to mouse macrophage-like Raw 264.7 cells. This supernatant dose-dependently inhibited the proliferation and nitric oxide (NO) production by lipopolysaccharide-stimulated Raw 264.7 cells. In Method II, human promyelocytic leukemic HL-60 cells in suspension were incubated with culture medium which contained Cu plate. The direct contact with Cu plate rapidly suppressed the proliferation and MnSOD and Cu/ZnSOD activities. The suppressed proliferation and SOD activity reverted to or exceeded the control level by sodium ascorbate, whereas N-acetyl-L-cysteine (NAC) only reactivated the proliferation, but not the SOD activity. ESR spectroscopy showed that contact with Cu plate slightly diminished the hydroxyl radical (generated by Fenton reaction), without affecting the intensity of NO (produced from NOC-7) and DPPH radical. The present study suggests that two representative antioxidants, such as sodium ascorbate and NAC, protect the cells from Cu-induced cytotoxicity via different mechanisms.
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PMID:Protection by antioxidants of copper-induced decline of proliferation and SOD activity. 1581 49

Induction of cytotoxicity and internucleosomal DNA fragmentation by 4-allyl-2-methoxyphenol (eugenol, EUG), 2-methoxy-4-methylphenol (MMP), 3,3'-dimethoxy-5,5'-di-2-propenyl-1,1'-biphenyl-2,2'-diol (bis-EUG) and 3,3'-di-methoxy-5,5'-dimethyl-1,1'-biphenyl-2,2'-diol (bis-MMP) were investigated in HL-60 leukemia cells. The 50% cytotoxic concentrations (CC50) for EUG, MMP, bis-EUG and bis-MMP were 0.38 mM, 0.38 mM, 0.18 mM and 0.20 mM, respectively. DNA fragmentation was induced most strongly by bis-EUG, followed by EUG, MMP and bis-MMP. The expression of MnSOD and, less strongly, Cu/ZnSOD activity, as assessed by acrylamide gel electrophoresis, was inhibited by EUG, suggesting mitochondrial dysfunction. The expression of the mRNAs for MnSOD and Cu/ZnSOD in HL-60 cells, as assessed by RT-PCR, was significantly inhibited by treatment with 1 mM EUG for 1 hour. Furthermore, inhibition of SOD mRNAs expression by EUG was strongly potentiated by the addition of 5 mM N-acetyl cysteine (NAC) or glutathione (GSH), whereas NAC or GSH alone did not affect the expression of SOD mRNAs. The cytotoxicity of EUG was significantly enhanced by high concentrations of NAC or GSH, which may be attributed to the inhibition of SOD mRNAs expression by the synergistic action of EUG and GSH or NAC. The regulatory effects of eugenol-related compounds on lipopolysaccharide (LPS)-induced cyclooxygenase-2 (COX-2) gene expression in RAW 264.7 cells were investigated by Northern blot analysis. Bis-EUG, MMP and bis-MMP inhibited COX-2 gene expression at concentrations of 300 microM, 500 microM and 500 microM, respectively. In contrast, no inhibitory effect of EUG was found over the wide concentration range of 10-500 microM, possibly as a result of the extensive mitochondrial dysfunction induced by this compound, which possesses potent pro-oxidative activity. Eugenol-related compounds, particularly bis-EUG, may act as nonsteroidal anti-inflammatory drug (NSAID)-like compounds.
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PMID:Induction of cytotoxicity and apoptosis and inhibition of cyclooxygenase-2 gene expression by eugenol-related compounds. 1610 Nov 37

Activation of both poly (ADP-ribose) polymerase (PARP) and inducible nitric oxide synthase (NOS-2) have been implicated in the pathogenesis of various forms of inflammation, therefore compounds which may simultaneously inhibit both pathways are of potential therapeutic interest. We tested the influence of potent inhibitor of PARP, 1, 5-isoquinolinediol (ISO), on NOS-2 induction in model of mouse macrophages (cell line J774.2) stimulated with lipopolysaccharide (1 microg/ml). Pretreatment with ISO (1-300 microM) resulted in dose-dependent inhibition of accumulation of NOS-2-derived nitrite in culture medium (IC(50) = 9,3 microM) as well as inhibition of NOS-2 protein induction in cultured J774.2 cells; ISO given 10 hours after LPS did not influence activity of NOS-2. Interestingly, another PARP inhibitor, 3-aminobenzamide (3-AB, 10-3000 microM), did not influence 24-hr nitrite accumulation in J774.2 cell culture, either administered 15 minutes prior to LPS or 10 hrs after LPS. Scavenging of reactive oxygen species by use of mixture of SOD and catalase (SOD/Cat, 100/300 - 1000/3000 U/ml) as well as cell permeable SOD-mimetic [Mn(III)TBAP, 1- 100 microM], did not influence NOS-2 induction in J774.2 cells. In summary, we identified 1, 5-isoquinoline as potent inhibitor of induction of NOS-2 in LPS-treated mouse macrophages. The exact mechanism of inhibitory action of this compound on NOS-2 induction requires further investigation.
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PMID:Inhibition of NOS-2 induction in LPS-stimulated J774.2 cells by 1, 5-isoquinolinediol, an inhibitor of PARP. 1660 19


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