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)

Many cell types are capable of expressing inducible nitric oxide synthase (iNOS) in response to cytokines or endotoxin. We detected iNOS mRNA by reverse transcriptase polymerase chain reaction in CD34+ human bone marrow cells after 48-hour incubation with interferon-gamma (IFN-gamma)/tumor necrosis factor alpha (TNF-alpha) and IFN-gamma/lipopolysaccharide. Based on this finding, we examined the effect of nitric oxide (NO) on hematopoiesis and particularly on proliferation and survival of CD34+ marrow cells in in vitro culture. When CD34+ cells were cultured in the presence of an NO donor, S-nitroso-N-acetyl-D,L-penicillamine (SNAP), a dose-dependent inhibition of cell proliferation was observed. Addition of the selective iNOS inhibitor, L-N6-(1-iminoethyl)-lysine hydrochloride (L-NIL) at a dose of 500 microM increased the cell counts by 23% (range 0-89%). The expansion of total CD34+ cell number was 4-fold with a hematopoietic cytokine cocktail compared to 5.2-fold with the addition of L-NIL to this combination. At days 7 and 14 of culture, SNAP induced apoptosis in CD34+ human bone marrow cells detected by an in situ terminal deoxynucleotidyl transferase assay. The apoptosis was partially inhibited with the addition of L-NIL. SNAP also inhibited cell cycling, as evidenced by a 56% decrease in the number of cells in S phase after 5 days of culture in the presence of SNAP. To investigate if NO production was dependent on oxygen tension, J774A mouse macrophage cells were induced with lipopolysaccharide/IFN-gamma, and nitrite production measured by the Griess reaction. Nitrite production was persistently less in 5% compared to 21% oxygen. CD34+ marrow cells from normal donors were also grown under variable oxygen tension, and the cell proliferation in 5% oxygen was significantly greater at both 7 and 14 days of culture. CFU-GM colony growth also was increased in the low oxygen setting. The concentration of various cytokines was measured in CD34+ progenitor culture supernatants, including interleukin (IL)-1 alpha, IL-1 beta and TNF-alpha. SNAP increased IL-1 alpha production by CD34+ cells as well as from light-density bone marrow cells, whereas the effect on IL-1 beta and TNF-alpha production was not significant. Manipulation of oxygen tension and the inhibition of production of reactive oxygen and nitrogen intermediates may have potential to optimize cell expansion and progenitor preservation in ex vivo culture systems.
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PMID:Effect of nitric oxide production and oxygen tension on progenitor preservation in ex vivo culture. 1008 6

Although several studies have demonstrated that low-dose, long-term 14-member macrolides (erythromycin (EM), roxithromycin (RXM), clarithromycin (CAM)) are effective in the treatment of chronic airway diseases like chronic sinusitis and diffuse panbronchiolitis (DPB), the mechanism of action of these drugs is not yet clear. Both these airway diseases are associated with an increase in the proliferation of fibroblasts. Moreover, fibroblasts are also an important source of proinflammatory cytokines such as interleukin-8 (IL-8), that play an important role in the pathogenesis of nasal polyps. Therefore, using primary fibroblast lines derived from nasal polyps, we investigated the effect of RXM on the synthesis of IL-8 and proliferation of nasal polyp fibroblasts (NPF). These fibroblasts were either treated with lipopolysaccharide (LPS) and RXM for 24 h, or pre-incubated with RXM for 24 h and then treated with LPS and RXM for 24 h. The level of IL-8 mRNA in NPF was analysed by reverse transcriptase-polymerase chain (RT-PCR) and the level of IL-8 in culture supernatants was measured by ELISA. Next, the proliferative capacity of NPF after treatment with RXM was analysed by cell counting and 3H-thymidine uptake. RXM had no effect on LPS-induced IL-8 synthesis by NPF. On the other hand, RXM suppressed the proliferation of NPF in a dose-dependent manner. These findings suggest that, although RXM cannot directly inhibit the synthesis of IL-8, it probably reduces IL-8 production by inhibiting the proliferation of NPF.
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PMID:Effect of roxithromycin on IL-8 synthesis and proliferation of nasal polyp fibroblasts. 1009 66

Flavonoids isolated from citrus were evaluated for their ability to affect the inflammation response through suppression of cytokine expression by human monocytes. Several polymethoxylated flavones inhibited lipopolysaccharide-induced monocyte expression of tumor necrosis factor (TNFalpha). Subsequent studies centered on the compound 3,5,6,7,8,3',4'-heptamethoxyflavone (HMF) which produced the highest inhibition (IC50 = 5 microM). HMF was also a potent inhibitor of macrophage inflammatory protein-1alpha (MIP-1alpha) and interleukin-10 (IL-10) production, but not of IL-1beta, IL-6, or IL-8 production. Suppression of TNFalpha production was at the level of mRNA induction as determined by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). HMF was also a potent inhibitor of human phosphodiesterase activity and was shown to induce a substantial elevation of cAMP levels in monocytes. The similarity of these results to the inhibition profile of the known phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine, suggests that the polymethoxylated flavones inhibit cytokine production in part by suppression of phosphodiesterase activity. The ability of HMF to also inhibit IL-10 production suggests the additional existence of a phosphodiesterase-independent mechanism for this compound.
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PMID:Polymethoxylated flavones derived from citrus suppress tumor necrosis factor-alpha expression by human monocytes. 1009 54

Human astrocytoma T67 cells constitutively express a neuronal NO synthase (NOS-I) and, following administration of lipopolysaccharide (LPS) plus interferon-gamma (IFNgamma), an inducible NOS isoform (NOS-II). Previous results indicated that a treatment of T67 cells with the combination of LPS plus IFNgamma, by affecting NOS-I activity, also inhibited NO production in a very short time. Here, we report that under basal conditions, a NOS-I protein of about 150 kDa was weakly and partially tyrosine-phosphorylated, as verified by immunoprecipitation and Western blotting. Furthermore, LPS plus IFNgamma increased the tyrosine phosphorylation of NOS-I, with a concomitant inhibition of its enzyme activity. The same effect was observed in the presence of vanadate, an inhibitor of phosphotyrosine-specific phosphatases. On the contrary, genistein, an inhibitor of protein-tyrosine kinases, reduced tyrosine phosphorylation of NOS-I, enhancing its enzyme activity. Finally, using reverse transcriptase-polymerase chain reaction, we have observed that a suboptimal induction of NOS-II mRNA expression in T67 cells was enhanced by vanadate (or L-NAME) and inhibited by genistein. Because exogenous NO has been found to suppress NOS-II expression, the decrease of NO production that we have obtained from the inactivation of NOS-I by LPS/IFNgamma-induced tyrosine phosphorylation provides the best conditions for NOS-II expression in human astrocytoma T67 cells.
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PMID:Rapid inactivation of NOS-I by lipopolysaccharide plus interferon-gamma-induced tyrosine phosphorylation. 1018 64

Oxidative stress and inflammatory reactions associated with stresses that may lead to shock promote hepatic microcirculatory dysfunction, which may lead to hepatic injury. Because altered liver microcirculation may result from an imbalance in the expression of stress-induced vasoactive mediators, our study was conducted to investigate changes in the expression of genes encoding endothelin-1 (ET-1), its receptors, ET(A) and ET(B), heme-oxygenase 1 (HO-1), and inducible nitric oxide synthase (iNOS), using two different rat models of liver stress: ischemia/reperfusion of the liver and lipopolysaccharide (LPS)-induced endotoxemia. In ischemia/reperfusion experiments, rats were subjected to 1 h hepatic ischemia, followed by 6 h of reperfusion. Endotoxemia was induced by i.p. injection of LPS (1 mg/mL/kg body weight); rats were studied after 6 h. mRNA levels were estimated using semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) on total RNA samples prepared from experimental and sham control rat livers. In the ischemic reperfused livers the levels of mRNA for ET-1, ET(B), HO-1, and iNOS were significantly elevated. The fold increase versus sham was 2.5+/-1.1 (ET-1), 2.1+/-1.3 (ET(B)), 2.1+/-.8 (HO-1), and 6.4+/-3.9 (iNOS). In contrast, the expression of ET(A) receptor gene was reduced after ischemia/reperfusion (to 73+/-1% of sham). In the separate experiments we analyzed the same mRNAs levels after 1 h of ischemia (no reperfusion), and did not detect any changes. During endotoxemia we observed a marked increase in iNOS mRNA level (>24-fold), as well as a marked elevation of the other four mRNAs. The fold increase versus sham was 6.1+/-1.7, ET-1); 1.5+/-.3 (ET(A)); 1.6+/-.4 (ET(B)); and 2.4+/-.34 (HO-1). These results show that liver stress, induced by ischemia/reperfusion or LPS injection have characteristic patterns of vasoregulatory genes expression indicating that, although both stresses result in an increase in specific vascular reactivity, different pathways are involved in inducing the hepatic vascular stress response.
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PMID:Patterns of vasoregulatory gene expression in the liver response to ischemia/reperfusion and endotoxemia. 1018 69

Interleukin 18 (IL-18) is a recently identified cytokine, originally called interferon gamma inducing factor, due to its capacity to induce interferon gamma production in Th1 type cells. IL-18 is expressed by a wide variety of cell types including mononuclear phagocytes, osteoblasts, keratinocytes and adrenal cortex cells. To quantify human IL-18 mRNA expression in small-scale cell samples the authors developed a competitive reverse transcriptase polymerase chain reaction using a competitive template as an internal standard. This assay was demonstrated as a valid, sensitive and precise tool to quantify human IL-18 mRNA expression. IL-18 mRNA expression of primary peripheral blood monocytes, CD4(+)T cells, CD8(+)T cells, B cells and NK cells was assessed by competitive RT-PCR. Basal IL-18 expression could be detected in all types of peripheral blood mononuclear cells (PBMC). The kinetics of IL-18 mRNA expression in PBMC from healthy donors was defined in vitro after monocyte-specific (lipopolysaccharide LPS), T-cell-specific (anti-CD3) and polyclonal-unspecific stimulation (phytohaemagglutinin PHA). Only LPS led to a strong increase of IL-18 mRNA expression peaking after 2 h. These results indicate that IL-18 is expressed constitutionally by all major PBMC subtypes. However, only monocyte specific stimulation resulted in a significant induction of IL-18 mRNA expression suggesting activated monocytes e.g. in inflammation as the main source of IL-18 expression.
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PMID:Quantification of human interleukin 18 mRNA expression by competitive reverse transcriptase polymerase chain reaction. 1034 85

We investigated the effect of tetrahydroswertianolin (THS), a hepatoprotective agent from Swertia japonica, on tumor necrosis factor-alpha (TNF-alpha)-dependent hepatic apoptosis induced by D-galactosamine (D-GalN) (700 mg/kg, i.p.) and lipopolysaccharide (LPS) (10 microg/kg, i.p.) in mice. Apoptotic symptoms were observed at the initial stage of liver damage. By 5 hr after intoxication, hepatic DNA fragmentation had risen to 2123%, with the value in untreated mice set at 100%, without a significant elevation of serum alanine transaminase (ALT) activity. There was a parallel increase in hepatocytes undergoing chromatin condensation and apoptotic body formation. By 8 hr after intoxication, serum ALT activity had risen to 3707 U/L. Pretreatment with THS (50 mg/kg, p.o.) at 18 and 2 hr before intoxication significantly reduced DNA fragmentation to 821% of that in untreated mice and prevented the emergence of chromatin condensation and apoptotic body formation. A significant and dose-dependent reduction in serum ALT activity at 8 hr also was observed with THS pretreatment. These effects of THS were different from those observed from pretreatment with glycyrrhizin (GCR), which is a clinically used hepatoprotective agent with membrane-stabilizing activity. GCR pretreatment (100 mg/kg, p.o.) did not inhibit hepatic DNA fragmentation (1588% of untreated mice), although this compound significantly protected against serum ALT elevation (1463 U/L). These data suggest that an inhibitory effect on the progression of hepatic apoptosis prior to liver injury may be involved in the hepatoprotective mechanisms of THS, whereas it appears that GCR affects the processes after apoptosis. In a separate experiment, we found that the concentration of serum TNF-alpha rose to 2016 pg/mL at 1 hr after intoxication of mice with D-GalN and LPS, but this increase was suppressed by THS pretreatment (10, 50, or 200 mg/kg, p.o.) to 716, 454, or 406 pg/mL, respectively. Further study with a reverse transcriptase-polymerase chain reaction method showed that THS blocked TNF-alpha production at the transcriptional level. Because TNF-alpha is a critical mediator to elicit apoptosis in this model, the property of suppressing TNF-alpha production may be of prime importance for THS inhibition of hepatic apoptosis.
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PMID:Inhibitory effect of tetrahydroswertianolin on tumor necrosis factor-alpha-dependent hepatic apoptosis in mice. 1035 65

Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a naturally occurring compound shown to inhibit carcinogen-induced preneoplastic lesion formation in mouse mammary organ culture and tumorigenesis in the two-stage mouse skin model. Cancer chemopreventive potential was also suggested in various assays reflective of the three major stages of carcinogenesis. Anti-initiation activity was indicated by its antioxidant and antimutagenic effects, inhibition of the hydroperoxidase function of cyclooxygenase (COX), and induction of phase II drug-metabolizing enzymes. Antipromotion activity was indicated by antiinflammatory effects, inhibition of production of arachidonic acid metabolites catalyzed by either COX-1 or COX-2, and chemical carcinogen-induced neoplastic transformation of mouse embryo fibroblasts. Antiprogression activity was demonstrated by its ability to induce human promyelocytic leukemia (HL-60) cell differentiation. Moreover, pretreatment of mouse skin with resveratrol significantly counteracted 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced oxidative stress, as evidenced by numerous biochemical responses. Resveratrol reduced the generation of hydrogen peroxide, and normalized levels of myeloperoxidase and oxidized-glutathione reductase activities. It also restored glutathione levels and superoxide dismutase activity. As judged by the reverse transcriptase-polymerase chain reaction, resveratrol selectively inhibited TPA-induced expression of c-fos and transforming growth factor-beta 1 (TGF-beta 1), but did not affect other TPA-induced gene products including COX-1, COX-2, c-myc, c-jun, and tumor necrosis factor-alpha. These data indicate that resveratrol may interfere with reactive oxidant pathways and/or modulate the expression of c-fos and TGF-beta 1 to inhibit tumorigenesis in mouse skin. As reported herein, in addition to the activities described above, resveratrol inhibited the de novo formation of inducible nitric oxide synthase (iNOS) in mouse macrophages stimulated with lipopolysaccharide. This finding suggests an additional mechanism by which resveratrol may function as a cancer chemopreventive agent.
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PMID:Cancer chemopreventive activity of resveratrol. 1037 Aug 67

Nitric oxide (NO) and prostaglandins (PGs) modulate inflammatory and immune responses in the central nervous system (CNS). Both NO and PG synthesis have been described in appropriately stimulated astrocytes. In other systems, both positive and negative modulation of cyclooxygenase (COX) activity, hence PG synthesis, have been described by NO. Since interferon (IFN)-gamma is known to upregulate the production of NO from astrocytes, the present study was designed to investigate the effect of IFNgamma on PG production from activated astrocytes and to determine whether this effect is mediated by NO. Astrocytic PG production was induced by exposure of murine cortical cultures to lipopolysaccharide (LPS). This induction was time- and concentration-dependent, and prevented by inhibitors of transcription and translation, as well as the selective COX-2 inhibitor, NS-398. LPS-induced expression of COX-2 mRNA and protein was confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis, respectively. Exposure of LPS-treated astrocytes to IFNgamma resulted in a concentration-dependent decrease in PGE2 accumulation which was accompanied by a striking parallel increase in NO formation. However, the NOS inhibitors, N(G)-nitro-L-arginine or N6-(1-iminoethyl)-lysine, failed to reverse the IFNgamma-mediated diminution of LPS-induced PGE2 production, indicating that the IFN-gamma-mediated reduction in COX-2-dependent PGE2 production occurred independent of NO formation. Additional experiments demonstrated that IFN-gamma acted mainly by downregulating the expression of COX-2 protein. Present results indicate that PG and NO synthesis in mouse cortical astrocytes in vitro are under the direct reciprocal control of IFNgamma.
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PMID:Interferon-gamma reduces cyclooxygenase-2-mediated prostaglandin E2 production from primary mouse astrocytes independent of nitric oxide formation. 1037 46

Nitric oxide (NO) is produced by various cell types, and it is an important mediator in many biological processes, including macrophage-mediated cellular host defense. The relevance and amount of NO production in peritonitis during peritoneal dialysis (PD) treatment is still not clear. We studied whether human peritoneal macrophages (PMphi) isolated from healthy PD patients or PD patients with peritonitis showed different spontaneous or lipopolysaccharide (LPS)/interferon gamma (IFN-gamma)-induced NO production (LPS, 1 ng/mL-10 microg/mL; IFN-gamma, 10-1000 U/mL; incubation between 6-48 hours; measured by Griess reagent). Results were compared with human blood monocytes (HBM) isolated from buffy coats. Inducible nitric oxide synthetase (iNOS) mRNA expression was looked for in PMphi by reverse transcriptase polymerase chain reaction (RT-PCR). Furthermore, plasma (P) and peritoneal dialysate effluent (D) nitrite concentrations were measured in vivo. The dialysate-to-plasma ratio (D/P) of nitrite concentration was inverse in the case of peritonitis compared to infection-free patients (peritonitis D/P = 1.3, non peritonitis D/P = 0.4; p < 0.01). PMphi from peritonitis patients produced higher amounts of NO than did those from infection-free patients (0.040+/-0.044 nmol per microgram cell protein versus 0.018+/-0.015 nmol per microgram cell protein, p < 0.05). NO release could not be further enhanced by stimulation with LPS plus IFN-gamma (1 ng/mL, 250 U/mL, respectively). However, NO production in PMphi from infection-free patients increased during in vitro stimulation (0.044+/-0.031 nmol per microgram cell protein versus 0.018+/-0.015 nmol per microgram cell protein, p < 0.01). An increase of iNOS mRNA expression could be demonstrated by RT-PCR. Blood monocytes from healthy donors also increased NO release during cytokine stimulation (0.032+/-0.015 nmol per microgram cell protein versus 0.019+/-0.009 nmol per microgram cell protein, p < 0.05). Our results indicate that significant amounts of NO are released intraperitoneally in the case of bacterial peritonitis. PMphi represent a site of NO production, though the absolute amounts released in vitro are only moderate. NO production can be induced in PMphi and HBM by LPS/IFN-gamma stimulation in vitro.
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PMID:Nitric oxide production in peritoneal macrophages from peritoneal dialysis patients with bacterial peritonitis. 1040 50


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