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

The peroxisome proliferator-activated receptor-gamma (PPARgamma) is activated by 15-deoxy-delta(12,14) prostaglandin J2 (15d-PGJ2), anti-diabetic thiazolidinediones and several non-steroidal anti-inflammatory drugs (NSAIDs). In rat glial cells, lipopolysaccharide and interferon-gamma (LPS/IFN-gamma) induced expression of both inducible nitric oxide synthase (iNOS) and heme oxygenase-1 (HO-1). PPARgamma activators inhibited iNOS expression by LPS and IFN-gamma. However, PPARgamma activator alone induced HO-1 expression and further enhanced LPS/IFN-gamma-induced HO-1 expression. These results suggest that activation of PPARgamma negatively regulate iNOS expression and positively regulates HO-1 expression in glial cells.
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PMID:Activators of peroxisome proliferator-activated receptor-gamma (PPARgamma) inhibit inducible nitric oxide synthase expression but increase heme oxygenase-1 expression in rat glial cells. 1020 48

We investigated the effects of troglitazone on cytokine-stimulated nitric oxide (NO) production in cultured rat vascular smooth muscle cells (VSMC). The increase in NO formation caused by interleukin-1alpha (IL-1) was enhanced by troglitazone in a concentration-dependent manner. Bacterial lipopolysaccharide-stimulated NO synthesis was also increased by troglitazone. The combinations of IL-1, tumor necrosis factor-alpha, or lipopolysaccharide with interferon-gamma (IFN) were strong stimuli for induction of NO synthesis in VSMC, which were further potentiated by the presence of troglitazone. When troglitazone was added at increasing intervals after the stimulation of VSMC with IL-1, the enhancement in NO production decreased as the interval lengthened, suggesting that troglitazone alters NO synthase (NOS) expression by VSMC rather than having a direct affect on VSMC NOS activity. Troglitazone had no effect on IL-1-elicited or IL-1/IFN-elicited nuclear factor-kappaB activity in VSMC. Troglitazone inhibited the degradation of cytokine-induced NOS mRNA. Thus troglitazone appears to enhance IL-1-induced NOS mRNA levels by prolonging its half-life rather than activating its transcription, which is nuclear factor -kappaB-dependent. No expression of peroxisome proliferator-activated receptor-gamma (PPARgamma) was detected in VSMC, and 15-deoxy-D12,14 prostaglandin J2, the natural ligand for the PPARgamma, did not resemble the effect of troglitazone on IL-1-induced NO synthesis. These results indicate that troglitazone upregulates cytokine-stimulated NO synthesis in VSMC through PPARgamma-independent mechanisms. Considering its inhibitory effects on the action of numerous growth factors on VSMC, the direct vascular effects of troglitazone shown in this study may have important implications for prevention of restenosis and possibly atherosclerosis.
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PMID:Troglitazone upregulates nitric oxide synthesis in vascular smooth muscle cells. 1020 28

Administration of the bacterial endotoxin lipopolysaccharide (LPS) causes induction of cytochrome P-450 (CYP) 4A mRNAs in rat liver and kidney. Because induction of the CYP4A subfamily by chemicals requires peroxisome proliferator-activated receptor-alpha (PPARalpha), we determined whether CYP4A induction by LPS also requires PPARalpha by comparing the responses of PPARalpha-null (-/-) and wild-type (+/+) mice. Renal expression of CYP4A10, CYP4A14, and acyl-CoA oxidase was induced by LPS treatment in (+/+) mice, and these effects were absent in the (-/-) mice. In contrast, hepatic expression of CYP4A10 was down-regulated in the (+/+) animals, and no significant induction of acyl-CoA oxidase or CYP4A14 was detected in liver. Expression of the peroxisomal bifunctional enzyme was not significantly affected by LPS treatment. These results indicate that PPARalpha is activated in mouse kidney after LPS treatment and that this leads to modulation of some PPARalpha-regulated genes. However, the species and tissue specificity of these effects suggest that inflammatory pathways may modulate the induction via PPARalpha. Mice pair fed with LPS-treated mice showed no induction of renal CYP4A10 or CYP4A14, indicating that renal CYP4A induction during endotoxemia is not due to hypophagia. Down-regulation of CYP2A5, CYP2C29, and CYP3A11 by LPS was attenuated or blocked in the (-/-) mice, suggesting a role for PPARalpha in CYP down-regulation as well. Finally, we found that clofibrate caused an acute induction of two hepatic acute-phase mRNAs that was only partially dependent on PPARalpha.
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PMID:Modulation of cytochrome P-450 gene expression in endotoxemic mice is tissue specific and peroxisome proliferator-activated receptor-alpha dependent. 1045 1

Cerebellar granule cells (CGCs) can express the inducible isoform of nitric oxide synthase (iNOS) in response to inflammatory stimuli. We demonstrate that induction of iNOS in CGCs by bacterial lipopolysaccharide and pro-inflammatory cytokines results in cell death that was potentiated by excess L-arginine and inhibited by the selective iNOS inhibitor, 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine. The NO-mediated cell death was accompanied by increased caspase-3-like activity, DNA fragmentation and positive terminal transferase dUTP nick end labeling (TUNEL), suggesting that apoptosis mediates CGC cell death. Incubation of CGCs with the non-steroidal anti-inflammatory drugs (NSAIDs), ibuprofen or indomethacin, or with 15-deoxy-delta12,14 prostaglandin J2 (PGJ2) downregulates iNOS expression and reduces subsequent cell death. Since in other cell types, both NSAIDs and PGJ2 can activate the peroxisome proliferator-activated receptor-gamma (PPARgamma) and downregulate cytokine levels and iNOS expression, and since CGCs express PPARgamma in vivo and in vitro, our data suggest that activation of CGC PPARgamma mediates iNOS suppression and reduced cell death. Because PPARgamma is expressed in brains of Alzheimer's Disease (AD) patients, in which neuronal iNOS expression and apoptotic cell death have been described, these results may help explain the basis for the beneficial effects of NSAIDs in AD.
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PMID:Peroxisome proliferator-activated receptor gamma agonists protect cerebellar granule cells from cytokine-induced apoptotic cell death by inhibition of inducible nitric oxide synthase. 1069 26

Troglitazone, a novel thiazolidinedione drug used to treat non-insulin-dependent diabetes mellitus, is a selective ligand for the peroxisome proliferator-activated receptor-gamma (PPARgamma). Recent results indicate that PPARgamma activation by thiazolidinediones regulates adipose tissue- and monocyte/peritoneal macrophage-derived cytokine expression in vitro. We evaluated whether troglitazone may also negatively regulate cytokine expression in the liver, which harbors the majority of the body's resident macrophages but which only weakly expresses PPARgamma. Lean C57BL6 mice and genetically obese KKA(y) mice were chronically treated with troglitazone (100 mg/kg/day for 2 weeks). At the end of treatment, hepatic expression of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 mRNA was quantitatively determined by kinetic polymerase chain reaction both under basal conditions and after stimulation with lipopolysaccharide (LPS). Both untreated lean and obese mice exhibited low levels of baseline TNF-alpha and IL-6 mRNA expression and responded with a dramatic increase in hepatic cytokine transcripts and TNF-alpha protein expression following a challenge with LPS. Similar to the effects on white adipose tissue, troglitazone not only down-regulated the baseline levels of hepatic TNF-alpha and IL-6, but also greatly attenuated the inducing effects of LPS. The extent of this inhibitory effect of troglitazone was higher in obese KKA(y) mice than in lean mice and was also reflected by markedly down-regulated hepatic TNF-alpha protein expression. These data demonstrate that chronic administration of troglitazone is associated with a greatly attenuated responsiveness towards inducers of hepatic TNF-alpha and IL-6 production. The possible biological consequences of these effects, however, have not yet been assessed.
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PMID:Down-regulation by troglitazone of hepatic tumor necrosis factor-alpha and interleukin-6 mRNA expression in a murine model of non-insulin-dependent diabetes. 1080 46

Interleukin-4 (IL-4) likely is one of the key players in the concert of immunosuppressive factors in brain. Therefore, influences of the cytokine on mRNA expression of endogenous mediators of inflammation, such as cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), tumor necrosis factor-alpha (TNF-alpha), interferon-inducible protein 10 (IP-10), interleukin-3 receptor-beta (IL-3R-beta), and of another antiinflammatory cytokine, IL-10, have been evaluated in the present study by semi-quantitative RT-PCR. Primary rat mixed glial cultures and isolated microglial cells, the resident immunocytes of the brain, have been used as rich sources of these mRNAs in response to the bacterial cell wall component lipopolysaccharide (LPS). Time-course studies showed peak levels of LPS-increased mRNAs at approximately 4 h. Interestingly, IL-10 mRNA was elevated also upon the LPS-stimulus. IL-4, given 30 min before LPS, inhibited increases of all mRNAs significantly, including IL-10 mRNA. IL-4, however, induced peroxisome proliferator-activated receptor (PPAR)-gamma in cultured microglia. This induction was completely inhibited by simultaneous administration of LPS. The data confirms IL-4 as an important antiinflammatory cytokine and gives some idea of cross-talk between intracellular signaling evoked by pro- and antiinflammatory substances.
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PMID:Interleukin-4-inhibited mRNA expression in mixed rat glial and in isolated microglial cultures. 1081 87

Cyclooxygenase-2 (COX-2), a rate-limiting enzyme for prostaglandins (PG), plays a key role in inflammation, tumorigenesis, development, and circulatory homeostasis. The PGD(2) metabolite 15-deoxy-Delta(12, 14) PGJ(2) (15d-PGJ(2)) was identified as a potent natural ligand for the peroxisome proliferator-activated receptor-gamma (PPARgamma). PPARgamma expressed in macrophages has been postulated as a negative regulator of inflammation and a positive regulator of differentiation into foam cell associated with atherogenesis. Here, we show that 15d-PGJ(2) suppresses the lipopolysaccharide (LPS)-induced expression of COX-2 in the macrophage-like differentiated U937 cells but not in vascular endothelial cells. PPARgamma mRNA abundantly expressed in the U937 cells, not in the endothelial cells, is down-regulated by LPS. In contrast, LPS up-regulates mRNA for the glucocorticoid receptor which ligand anti-inflammatory steroid dexamethasone (DEX) strongly suppresses the LPS-induced expression of COX-2, although both 15d-PGJ(2) and DEX suppressed COX-2 promoter activity by interfering with the NF-kappaB signaling pathway. Transfection of a PPARgamma expression vector into the endothelial cells acquires this suppressive regulation of COX-2 gene by 15d-PGJ(2) but not by DEX. A selective COX-2 inhibitor, NS-398, inhibits production of PGD(2) in the U937 cells. Taking these findings together, we propose that expression of COX-2 is regulated by a negative feedback loop mediated through PPARgamma, which makes possible a dynamic production of PG, especially in macrophages, and may be attributed to various expression patterns and physiological functions of COX-2.
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PMID:Feedback control of cyclooxygenase-2 expression through PPARgamma. 1082 78

In this study, the anti-inflammatory actions of the peroxisome proliferator-activated receptor (PPAR)-gamma agonists 15-deoxy-delta 12,14-prostaglandin J2 (15-d-delta 12,14-PGJ2) and troglitazone have been examined. Treatment of RAW 264.7 cells and CD-1 mouse peritoneal macrophages with lipopolysaccharide (LPS) + interferon-gamma (IFN-gamma) results in inducible nitric oxide synthase (iNOS), inducible cyclooxygenase (COX-2) and interleukin-1 (IL-1) expression, increased production of nitric oxide, and the release of IL-1. In a concentration-dependent manner, 15-d-delta 12,14-PGJ2 inhibits each of these proinflammatory actions of LPS + IFN-gamma, with half-maximal inhibition at approximately 0.5 microg/ml and complete inhibition at 1-5 microg/ml. The inhibitory actions of 15-d-delta 12,14-PGJ2 on LPS + IFN-gamma-induced inflammatory events are not associated with the inhibition of iNOS enzymatic activity or macrophage cell death, but appear to result from an inhibition of iNOS and IL-1 transcription. In addition, the anti-inflammatory actions of 15-d-delta 12,14-PGJ2 are not limited to peritoneal macrophages, as 15-d-delta 12,14-PGJ2 prevents TNF-alpha + LPS-induced resident islet macrophage expression of IL-1beta and beta-cell expression of iNOS stimulated by the local release of IL-1 in rat islets. 15-d-delta 12,14-PGJ2 appears to be approximately 10-fold more effective at inhibiting resident islet macrophage activation (in response to TNF + LPS) than IL-1-induced nitrite production by beta-cells. Two mechanisms appear to be associated with the antiinflammatory actions of both 15-d-delta 12,14-PGJ2 and troglitazone: 1) the direct inhibition of cytokine- and endotoxin-stimulated iNOS and IL-1 transcription; and 2) the inhibition of IL-1 signaling, an event associated with PPAR-gamma agonist-induced activation of the heat shock response (as assayed by heat shock protein 70 expression). These findings indicate that the PPAR-gamma agonists, troglitazone and the J series of prostaglandins, are potent anti-inflammatory agents that prevent cytokine- and endotoxin-stimulated activation of peripheral and resident tissue macrophages and cytokine-induced iNOS expression by beta-cells by the inhibition of transcriptional activation and induction of the heat shock response.
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PMID:Anti-inflammatory actions of 15-deoxy-delta 12,14-prostaglandin J2 and troglitazone: evidence for heat shock-dependent and -independent inhibition of cytokine-induced inducible nitric oxide synthase expression. 1086 55

Matrix metalloproteinase-9 (MMP-9) may play an important role in the development of inflammatory bowel disease (IBD). However, the cellular source of MMP-9 in the inflamed mucosa of IBD remains unclear. Here we report that MMP-9 mRNA is expressed in CaCO-2 cells, an intestinal epithelial cell line, and that its expression is upregulated by inflammatory stimuli. Stimulation of CaCO-2 cells with interleukin-1beta (IL-1beta) or tumor necrosis factor-alpha (TNF-alpha) led to a dose-dependent increase in expression and secretion of MMP-9. In contrast, bacterial lipopolysaccharide (LPS) failed to induce expression or secretion of MMP-9, suggesting that an inflammatory reaction leading to cytokine release is a necessary step for the induction of MMP-9 release in intestinal epithelial cells. Additional studies show that induction of MMP-9 mRNA peaked at 16 h of IL-1beta stimulation, whereas expression of monocyte chemoattractant protein-1 (MCP-1) and IL-8 both peaked at 3 h of stimulation. Treatment of CaCO-2 cells with rosiglitazone, a peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonist, significantly reduced secretion of MMP-9, indicating that agents that activate PPAR-gamma may have therapeutic use in patients with IBD.
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PMID:Production of matrix metalloproteinase-9 in CaCO-2 cells in response to inflammatory stimuli. 1124 73

Amyloid deposition within the brains of Alzheimer's Disease patients results in the activation of microglial cells and the induction of a local inflammatory response. The interaction of microglia or monocytes with beta-amyloid (A beta) fibrils elicits the activation a complex tyrosine kinase-based signal transduction cascade leading to stimulation of multiple independent signaling pathways and ultimately to changes in proinflammatory gene expression. The A beta-stimulated expression of proinflammatory genes in myeloid lineage cells is antagonized by the action of a family of ligand-activated nuclear hormone receptors, the peroxisome proliferator-activated receptors (PPARs). We report that THP-1 monocytes express predominantly PPAR gamma isoform and lower levels of PPAR alpha and PPAR delta isoforms. PPAR mRNA levels are not affected by differentiation of the cells into a macrophage phenotype, nor are they altered following exposure to the classical immune stimulus, lipopolysaccharide. Previous studies have found that PPAR gamma agonists act broadly to inhibit inflammatory responses. The present study explored the action of the PPAR alpha isoform and found that PPAR alpha agonists inhibited the A beta-stimulated expression of TNFalpha and IL-6 reporter genes in a dose-dependent manner. Moreover, the PPAR alpha agonist WY14643 inhibited macrophage differentiation and COX-2 gene expression. However, the PPAR alpha agonists failed to inhibit A beta-stimulated elaboration of neurotoxic factors by THP-1 cells. These findings demonstrate that PPAR alpha acts to suppress a diverse array of inflammatory responses in monocytes.
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PMID:Regulation of beta-amyloid stimulated proinflammatory responses by peroxisome proliferator-activated receptor alpha. 1157 80


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