Induction of COX‐2 and PGE2 biosynthesis by IL‐1β is mediated by PKC and mitogen‐activated protein kinases in murine astrocytes

British Journal of Pharmacology (Impact Factor: 4.99). 08/2000; 131(1):152 - 159. DOI: 10.1038/sj.bjp.0703557

ABSTRACT Interleukin-1 (IL-1) is an important mediator of immunoinflammatory responses in the brain. In the present study, we examined whether prostaglandin E2 (PGE2) production after IL-1β stimulation is dependent upon activation of protein kinases in astroglial cells.Astrocyte cultures stimulated with IL-1β or the phorbol ester, PMA significantly increased PGE2 secretion. The stimulatory action of IL-1β on PGE2 production was totally abolished by NS-398, a specific inhibitor of cyclo-oxygenase-2 activity, as well as by the protein synthesis inhibitor cycloheximide, and the glucocorticoid dexamethasone. Furthermore, IL-1β induced the expression of COX-2 mRNA. This occurred early at 2 h, with a maximum at 4 h and declined at 12 h. IL-1 β treatment also induced the expression of COX-2 protein as determined by immunoblot analysis. In that case the expression of the protein remained high at least up to 12 h.Treatment of cells with protein kinase C inhibitors (H-7, bisindolylmaleimide and calphostin C) inhibited IL-1β stimulation of PGE2. In addition, PKC-depleted astrocyte cultures by overnight treatment with PMA no longer responded to PMA or IL-1. The ablation of the effects of PMA and IL-1β on PGE2 production, likely results from down-regulation of phorbol ester sensitive-PKC isoenzymes. Immunoblot analysis demonstrated the translocation of the conventional isoform cPKC-α from cytosol to membrane following treatment with IL-1β.In addition, IL-1β treatment led to activation of extracellular signal-regulated kinase (ERK1/2) and p38 subgroups of MAP kinases in astroglial cells. Interestingly, the inhibition of ERK kinase with PD 98059, as well as the inhibition of p38 MAPK with SB 203580, prevented IL-1β-induced PGE2 release.ERK1/2 activation by IL-1β was sensitive to inhibition by the PKC inhibitor bisindolylmaleimide suggesting that ERK phosphorylation is a downstream signal of PKC activation.These results suggest key roles for PKC as well as for ERK1/2 and p38 MAP kinase cascades in the biosynthesis of PGE2, likely by regulating the induction of cyclo-oxygenase-2, in IL-1β-stimulated astroglial cells.British Journal of Pharmacology (2000) 131, 152–159; doi:10.1038/sj.bjp.0703557

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Available from: Francisco Molina-Holgado, Aug 04, 2015
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    • "Of these, the IL-1β isoform is by far the most often reported in TBI. IL-1β is a pro-inflammatory cytokine and has been implicated in the release of phospholipase-2 (PLA2), prostaglandins, and the activation of cyclooxygenase-2 (COX-2; Chung and Benveniste, 1990; Aloisi et al., 1992; Molina-Holgado et al., 2000; Rothwell, 2003). Furthermore, the primary mechanism of action for IL- 1β is believed to be the regulation of release of other cytokines. "
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    ABSTRACT: Within minutes of a traumatic impact, a robust inflammatory response is elicited in the injured brain. The complexity of this post-traumatic squeal involves a cellular component, comprising the activation of resident glial cells, microglia, and astrocytes, and the infiltration of blood leukocytes. The second component regards the secretion immune mediators, which can be divided into the following sub-groups: the archetypal pro-inflammatory cytokines (Interleukin-1, Tumor Necrosis Factor, Interleukin-6), the anti-inflammatory cytokines (IL-4, Interleukin-10, and TGF-beta), and the chemotactic cytokines or chemokines, which specifically drive the accumulation of parenchymal and peripheral immune cells in the injured brain region. Such mechanisms have been demonstrated in animal models, mostly in rodents, as well as in human brain. Whilst the humoral immune response is particularly pronounced in the acute phase following Traumatic brain injury (TBI), the activation of glial cells seems to be a rather prolonged effect lasting for several months. The complex interaction of cytokines and cell types installs a network of events, which subsequently intersect with adjacent pathological cascades including oxidative stress, excitotoxicity, or reparative events including angiogenesis, scarring, and neurogenesis. It is well accepted that neuroinflammation is responsible of beneficial and detrimental effects, contributing to secondary brain damage but also facilitating neurorepair. Although such mediators are clear markers of immune activation, to what extent cytokines can be defined as diagnostic factors reflecting brain injury or as predictors of long term outcome needs to be further substantiated. In clinical studies some groups reported a proportional cytokine production in either the cerebrospinal fluid or intraparenchymal tissue with initial brain damage, mortality, or poor outcome scores. However, the validity of cytokines as biomarkers is not broadly accepted. This review article will discuss the evidence from both clinical and laboratory studies exploring the validity of immune markers as a correlate to classification and outcome following TBI.
    Frontiers in Neurology 03/2013; 4:18. DOI:10.3389/fneur.2013.00018
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    • "In all of these diseases, astrocytes and microglia are the major sources of COX-2 and PGE 2 (Mingetti et al, 1999; Molina-Holgado et al, 2000). Virus infections in general tend to stimulate COX-2 expression (Murono et al, 2001; Janelle et al, 2002; Seymour et al, 2002), and inhibitors of COX-2 activity attenuate virus replication (Chen et al, 2000; Zhu et al, 2002), suggesting that COX-2 activation and the cellular events that follow are important determinants governing viral replication and the spread of infection and cellular damage in the CNS. "
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    ABSTRACT: In susceptible strains of mice, infection with the mutant retrovirus MoMuLV-ts1 causes a neurodegeneration and immunodeficiency syndrome that resembles human human immunodeficiency virus-acquired immunodeficiency syndrome (HIV-AIDS). In this study the authors show increased expression of cyclooxygenase-2 (COX-2) in the brainstem tissues of ts1-infected mice. Up-regulated central nervous system (CNS) levels of this enzyme are associated with HIV-associated dementia and other inflammatory and neurodegenerative diseases such as amyotrophic lateral sclerosis, Alzheimer's disease, and Parkinson's disease. In brainstem sections, the authors find that astrocytes surrounding spongiform lesions contain increased amounts of immunoreactive COX-2. COX-2 is also up-regulated in cultured ts1-infected cells from the C1 astrocytic cell line, and activation of c-Jun N-terminal kinase, or JNK, pathway. Markers of endoplasmic reticulum (ER) stress, specifically the CCAAT/enhancer-binding protein (CHOP), the glucose-related protein 78 (GRP78), and phosphorylated eukaryotic initiation factor 2 alpha (eIF2 alpha), were also up-regulated in ts1-infected C1 astrocytes. Up-regulation of COX-2 and the above ER signaling factors was reversed by treatment of the infected cells with curcumin which specifically inhibits the JNK/c-Jun pathway. These findings indicate that the JNK/c-Jun pathway is most likely responsible for COX-2 expression induced by ts1 in astrocytes, and that ts1 infection in astrocytes may lead to up-regulation of both inflammatory and ER stress pathways in the central nervous system. Because COX-2 inhibitors are now widely used to treat inflammatory conditions in animals and humans, this finding suggests that these drugs may be useful for therapeutic intervention in neurodegenerative syndromes as well.
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    • "First, astrocyte–monocyte cocultures are an established in vitro model and have been used extensively in the study of HIV-1-associated dementia (Genis et al., 1992; Fiala et al., 1996; Pereira et al., 2001) and chemokine expression in the CNS (Andjelkovic et al., 2000). Second, the capacity of astrocytes to produce PGE 2 after stimulation with IL-1␤ or TNF-␣ has been well documented (Janabi et al., 1999; Pistritto et al., 1999; Molina-Holgado et al., 2000). Third, although astrocytes produce copious amounts of PGE 2 , we have found that they do not express OSM in response to IL-1␤ or PGE 2 stimulation (Fig. 8 D) (data not shown). "
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