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)

Oncostatin M (OM) is a pleiotropic cytokine of the interleukin 6 family, whose in vivo properties and physiological function remain in dispute and poorly defined. These in vivo studies strongly suggest that OM is anabolic, promoting wound healing and bone formation, and anti-inflammatory. In models of inflammation OM is produced late in the cytokine response and protects from lipopolysaccharide (LPS)-induced toxicities, promoting the re-establishment of homoeostasis by cooperating with proinflammatory cytokines and acute phase molecules to alter and attenuate the inflammatory response. Administration of OM inhibited bacterial LPS-induced production of tumour necrosis factor alpha and septic lethality in a dose dependent manner. Consistent with these findings, in animal models of chronic inflammatory disease OM potently suppressed inflammation and tissue destruction in murine models of rheumatoid arthritis and multiple sclerosis. T cell function and antibody production were not impaired by OM treatment. Taken together, these data indicate that the activities of this cytokine in vivo are anti-inflammatory without concordant immunosuppression.
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PMID:Oncostatin M in the anti-inflammatory response. 1189 Jun 61

The immediate or innate immune response is the first line of defense against diverse microbial pathogens and requires the expression of recently discovered toll-like receptors (TLRs). TLR4 serves as a specific receptor for lipopolysaccharide (LPS) and is localized on the surface of a subset of mammalian cells. Although innate immunity is a necessary host defense against microbial pathogens, the consequences of its activation in the CNS can be deleterious, as we show here in a developing neural model. We examined the major non-neuronal cell types in the CNS for expression of TLR4 and found that microglia expressed high levels, whereas astrocytes and oligodendrocytes expressed none. Consistent with TLR4 expression solely in microglia, we show that microglia are the only CNS glial cells that bind fluorescently tagged lipopolysaccharide. Lipopolysaccharide led to extensive oligodendrocyte death in culture only under conditions in which microglia were present. To determine whether TLR4 is necessary for lipopolysaccharide-induced oligodendrocyte death in mixed glial cultures, we studied cultures generated from mice bearing a loss-of-function mutation in the tlr4 gene. Lipopolysaccharide failed to induce oligodendrocyte death in such cultures, in contrast to the death induced in cultures from wild-type mice. Finally, stereotactic intracerebral injection of lipopolysaccharide into the developing pericallosal white matter of immature rodents resulted in loss of oligodendrocytes and hypomyelination and periventricular cysts. Our data provide a general mechanistic link between (1) lipopolysaccharide and similar microbial molecular motifs and (2) injury to oligodendrocytes and myelin as occurs in periventricular leukomalacia and multiple sclerosis.
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PMID:The toll-like receptor TLR4 is necessary for lipopolysaccharide-induced oligodendrocyte injury in the CNS. 1192 12

Nitric oxide (NO) is considered to play a crucial role in the development of various pathological processes in the CNS, such as neuronal degeneration, inflammation and demyelination. In order to search for the agents which suppress NO production in the CNS, we examined the effects of one of the agents which elevate cyclic AMP production, phosphodiesterase inhibitors (PDEIs), on NO production by glial cells in vitro. All the types of PDEIs, from type I- to V-specific and non-specific, suppressed the production of NO by mouse microglia and astrocytes stimulated with lipopolysaccharide, in a dose-dependent manner. Suppression of inducible NO synthase by PDEIs was confirmed by the expression of mRNA by RT-PCR. Although it required 10 microM or higher concentration to effectively suppress NO production in vitro, certain combinations of three different PDEIs synergistically suppressed NO production by astrocytes at 1 microM which could be obtained in vivo at usual therapeutic doses. Similary, combinations of three PDEIs at 1 microM synergistically increased intracellular cAMP in astrocytes. The suppressive effects of PDEIs on NO production were abolished by addition of tumor necrosis factor alpha (TNFalpha). Thus, the main suppression mechanism of NO might be indirect through suppression of TNFalpha. Since some PDEIs are reported to pass through the blood-brain-barrier, the combination of three PDEIs may be worth trying in neurological diseases, such as multiple sclerosis, human immunodeficiency virus-related neurological diseases and other neurodegenerative disorders in which NO may play a crucial role.
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PMID:Effect of phosphodiesterase inhibitors on nitric oxide production by glial cells. 1200 73

Increasing evidence has suggested that inflammation in the brain is closely associated with the pathogenesis of several degenerative neurologic disorders, including Parkinson's disease, Alzheimer's diseases, multiple sclerosis, amyotrophic lateral sclerosis, and AIDS dementia. The hallmark of brain inflammation is the activation of glial cells, especially that of microglia that produce a variety of proinflammatory and neurotoxic factors, including cytokines, fatty acid metabolites, free radicals--such as nitric oxide (NO) and superoxide. Excessive production of NO, as a consequence of nitric oxide synthase induction in activated glia, has been attributed to participate in neurodegeneration. Using primary mixed neuron-glia cultures and glia-enriched cultures prepared from embryonic rodent brain tissues, we have systemically studied the relationship between the production of NO and neurodegeneration in response to stimulation by the inflammagen lipopolysaccharide. This review summarizes our recent findings on the kinetics of NO generation, the relative contribution of microglia and astrocytes to NO accumulation, the relationship between NO production and neurodegeneration, and points of intervention along the pathways associated with NO generation to achieve neuroprotection. We also describe our results relating to the effect of several opioid-related agents on microglial activation and neuroprotection. Among these agents, the opioid receptor antagonist naloxone, especially its non-opioid enantiomer (+)-naloxone, promises to be of potential therapeutic value for the treatment of inflammation-related diseases.
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PMID:Role of nitric oxide in inflammation-mediated neurodegeneration. 1207 84

Free radical nitric oxide (NO), generated by inducible nitric oxide synthase (iNOS) in astrocytes and macrophages, has been implicated in CNS inflammatory disorders such as multiple sclerosis and its animal model experimental autoimmune encephalomyelitis (EAE). Mycophenolic acid (MPA), a selective inhibitor of inosine monophosphate dehydrogenase (IMPDH), inhibited interferon-gamma (IFN-gamma) + lipopolysaccharide (LPS)-induced NO production dose-dependently in astrocytes, but not in macrophages. The effect of MPA was not mediated through interference with IMPDH-dependent synthesis of iNOS cofactor BH4 and subsequent suppression of iNOS enzymatic activity, as direct BH4 precursor sepiapterin failed to block the action of the drug. However, MPA markedly inhibited IFN-gamma + LPS-triggered astrocyte expression of mRNA for iNOS and its transcription factor IRF-1, while the expression of tumor necrosis factor-alpha (TNF-alpha) gene was not altered. The observed MPA suppression of NO release and iNOS and IRF-1 induction in astrocytes were efficiently prevented by exogenous guanosine, indicating that the drug acted through reduction of IMPDH-dependent synthesis of guanosine nucleotides. This IRF-1-dependent inhibition of iNOS activation might be partly responsible for the protective effect of MPA in EAE, prompting investigation of its potential use in multiple sclerosis.
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PMID:Mycophenolic acid downregulates inducible nitric oxide synthase induction in astrocytes. 1220 91

Nitric oxide (NO) has been implicated in the etiopathology of multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), and inhibition of NO synthesis has been proposed to be a possible mechanism of action of drugs to treat MS. In the present study, we investigated the inhibitory effect on NO synthesis of various steroids, cytokines and drugs used or proposed for the treatment of MS. As a model system, we used primary rat microglial cells which produce NO synthase and subsequently release NO upon stimulation with lipopolysaccharide (LPS). Among the substances tested, the glucocorticoids prednisone, hydrocortisone, dexamethasone and progesterone as well as transforming growth factor-beta (TGF-beta) dose-dependently inhibited LPS-induced nitric oxide synthase (iNOS) and NO synthesis. In contrast, COP-1, the phosphodiesterase inhibitors rolipram and pentoxifylline, the cytokines interleukin-10 (IL-10) and interferon-beta (IFN-beta) as well as the steroids beta-estradiol, testosterone, and dehydroepiandrosterone (DHEA) showed no inhibitory effect. Cholesterol slightly, but not significantly, increased LPS-induced nitric oxide synthesis. We conclude from the present study that with respect to treatment of MS, inhibition of NO synthesis may be an important mechanism of action of glucocorticoids and transforming growth factor-beta, but not of other drugs used or proposed to treat MS.
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PMID:Inhibition of LPS-induced iNOS and NO synthesis in primary rat microglial cells. 1242 93

Previous studies have demonstrated the immunomodulatory potential of Lovastatin, a hydroxy methyl glutaryl-CoA reductase inhibitor, in lessening the clinical and histological manifestations in the neuroinflammatory animal model experimental autoimmune encephalomyelitis (EAE) (Neurosci. Lett., 269 (1999) 71, and J. Neurosci. Res., 66 (2001) 155). To determine the mechanism behind the observed amelioration of EAE by Lovastatin, we examined the cytokine profile of stimulated splenocytes from control, EAE and Lovastatin treated EAE rats. Splenocytes from Lovastatin-treated EAE rats showed decreased levels of interferon-gamma, a Th1 type cytokine, while interleukin (IL)-10, a Th2 type cytokine, was markedly increased as compared to untreated EAE animals. In addition, we also observed reduced levels of IL-6 and nitric oxide production in lipopolysaccharide-stimulated splenocytes isolated from Lovastatin-treated animals. This study documents for the first time that Lovastatin induces a bias towards Th2 cytokines ex vivo, and as a result may be of therapeutic value for cell-mediated diseases such as multiple sclerosis.
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PMID:Immunomodulation of experimental autoimmune encephalomyelitis in the Lewis rats by Lovastatin. 1242 74

Microglial activation is an early and common feature of almost all neuropathologies, including multiple sclerosis, Alzheimer's disease and mechanical injury. To better understand the relative contributions microglia make toward neurodegeneration and neuroprotection, we used TOGA(R) to identify molecules expressed by microglia and regulated by inflammatory signals. Triggering receptor expressed on myeloid cells-2 (TREM-2) was among the mRNAs identified as being expressed by unactivated microglia, but down-regulated by lipopolysaccharide/interferon gamma. In the healthy CNS, not all microglia expressed TREM-2. Microglial expression of TREM-2 varied not only between brain regions but also within each brain region. Brain regions with an incomplete blood-brain barrier had the lowest percentages of TREM-2- expressing microglia, whereas the lateral entorhinal and cingulate cortex had the highest percentages. A novel form of TREM-2b that lacked a transmembrane domain was detected, perhaps indicating a soluble form of the protein. Taken together, these data suggest that (1) subsets of microglia are specialized to respond to defined extracellular signals; and (2) regional variations in TREM-2 expression may contribute to the varying sensitivities of different brain regions to similar pathological signals.
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PMID:Heterogeneous expression of the triggering receptor expressed on myeloid cells-2 on adult murine microglia. 1247 85

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system with heterogeneous pathological features, disease courses and genetical backgrounds. In this study we determined whether genetic variants of toll-like receptor (TLR) 4, which confer substantial differences in the inflammation elicited by bacterial lipopolysaccharide, are related to the development of MS. We found no differences in the frequencies of the cosegregating TLR4 Asp299Gly and Thr399Ile polymorphisms between Austrian MS patients (11.6%) and age-matched controls (13.7%). Furthermore, we could not detect any influence of these mutations on clinical parameters and serum levels of soluble adhesion molecules of MS patients. Our data indicate that these TLR4 polymorphisms have no influence on the incidence, progression and inflammatory parameters of MS.
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PMID:Mutations in the gene for toll-like receptor 4 and multiple sclerosis. 1262 79

Oncostatin M (OSM), a cytokine of the interleukin-6 family, is expressed in rheumatoid arthritis, multiple sclerosis, multiple myeloma, and other inflammatory and neoplastic conditions. Prostaglandin E(2) (PGE(2)), an eicosanoid also associated with inflammation and cancer, has recently been shown to induce OSM expression. We report here that OSM in turn induces PGE(2) production by astrocytes and astroglioma cells. More importantly, in combination with the inflammatory mediators IL-1beta, tumor necrosis factor-alpha, and lipopolysaccharide, OSM exhibits a striking synergy, resulting in up to 50-fold higher PGE(2) production by astrocytes, astroglioma, and neuroblastoma cell lines. Enhanced PGE(2) production by OSM and IL-1beta treatment is explained by their effect on cyclooxygenase-2 (COX-2), an enzyme that catalyzes the committed step in PGE(2) synthesis. Of the enzymes involved in PGE(2) biosynthesis, only COX-2 mRNA and protein levels are synergistically amplified by OSM and IL-1beta. Nuclear run-on assays demonstrate that OSM and IL-1beta synergistically upregulate transcription of the COX-2 gene, and the mRNA stability assay indicates that COX-2 mRNA is posttranscriptionally stabilized by OSM and IL-1beta. To effect synergy on the PGE(2) level, OSM signals in part through its gp130/OSMRbeta receptor, since neutralizing antibodies against gp130 and OSMRbeta, but not LIFRbeta, decrease PGE(2) production in response to OSM plus IL-1beta. SB202190 and U0126, inhibitors of p38 MAPK and ERK1/2 activation, respectively, inhibit IL-1beta and OSM upregulation of COX-2 and PGE(2), indicating that these MAPK cascades are utilized by both stimuli. This mechanism of PGE(2) amplification may be active in brain pathologies where both OSM and IL-1beta are present, such as glioblastomas and multiple sclerosis.
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PMID:Oncostatin M enhances the expression of prostaglandin E2 and cyclooxygenase-2 in astrocytes: synergy with interleukin-1beta, tumor necrosis factor-alpha, and bacterial lipopolysaccharide. 1273 Sep 64


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