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Prostaglandin E Synthase (prostaglandin + e_synthase)
Selected AbstractsProstaglandin E synthase in the pathophysiology of arthritisFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 3 2005Fumiaki Kojima Abstract Prostaglandin E synthase (PGES) is a recently identified terminal enzyme that acts downstream of cyclooxygenase and catalyzes the conversion of prostaglandin (PG) H2 to PGE2. At least three isozymes have been cloned so far, which are called membrane-associated PGES (mPGES)-1, mPGES-2, and cytosolic PGES. Among them, mPGES-1 is induced by various inflammatory stimuli in some cells and tissues. Induction of mPGES-1 in the component of articular tissues of patients with rheumatoid arthritis and osteoarthritis has been demonstrated in vitro. Recent studies using adjuvant induced arthritis model have shown the increase of mPGES-1 expression resulted in the increase of PGE2 production at the sites of inflammation. In addition, reports of mPGES-1-deficient mice clearly suggest the role of mPGES-1 in the process of chronic inflammation such as collagen-induced arthritis and collagen antibody induced arthritis in vivo. Thus, recent in vitro and in vivo findings suggest that mPGES-1 may be a novel therapeutic target for arthritis. This paper introduces recent advances in research about the role of PGES in the pathophysiology of arthritis. [source] Neuroprotective role of bradykinin because of the attenuation of pro-inflammatory cytokine release from activated microgliaJOURNAL OF NEUROCHEMISTRY, Issue 2 2007Mami Noda Abstract Bradykinin (BK) has been reported to be a mediator of brain damage in acute insults. Receptors for BK have been identified on microglia, the pathologic sensors of the brain. Here, we report that BK attenuated lipopolysaccharide (LPS)-induced release of tumor necrosis factor-alpha (TNF-,) and interleukin-1, from microglial cells, thus acting as an anti-inflammatory mediator in the brain. This effect was mimicked by raising intracellular cAMP or stimulating the prostanoid receptors EP2 and EP4, while it was abolished by a cAMP antagonist, a prostanoid receptor antagonist, or by an inhibitor of the inducible cyclooxygenase (cyclooxygenase-2). BK also enhanced formation of prostaglandin E2 and expression of microsomal prostaglandin E synthase. Expression of BK receptors and EP2/EP4 receptors were also enhanced. Using physiological techniques, we identified functional BK receptors not only in culture, but also in microglia from acute brain slices. BK reduced LPS-induced neuronal death in neuron,microglia co-cultures. This was probably mediated via microglia as it did not affect TNF-,-induced neuronal death in pure neuronal cultures. Our data imply that BK has anti-inflammatory and neuroprotective effects in the central nervous system by modulating microglial function. [source] Microparticles stimulate the synthesis of prostaglandin E2 via induction of cyclooxygenase 2 and microsomal prostaglandin E synthase 1ARTHRITIS & RHEUMATISM, Issue 11 2007Astrid Jüngel Objective Microparticles are small vesicles that are released from activated or dying cells and that occur abundantly in the synovial fluid of patients with rheumatoid arthritis (RA). The goal of these studies was to elucidate the mechanisms by which microparticles activate synovial fibroblasts to express a proinflammatory phenotype. Methods Microparticles from monocytes and T cells were isolated by differential centrifugation. Synovial fibroblasts were cocultured with increasing numbers of microparticles. Gene expression was analyzed by real-time polymerase chain reaction and confirmed by Western blotting and enzyme immunoassay. Arachidonic acid labeled with tritium was used to study the transport of biologically active lipids by microparticles. The roles of NF-,B and activator protein 1 (AP-1) signaling were analyzed with electrophoretic mobility shift assay and transfection with small interfering RNA and I,B expression vectors. Results Microparticles strongly induced the synthesis of cyclooxygenase 2 (COX-2), microsomal prostaglandin E synthase 1 (mPGES-1), and prostaglandin E2 (PGE2). In contrast, no up-regulation of COX-1, mPGES-2, cytosolic PGES, or phospholipase A2 was observed. The induction of PGE2 was blocked by selective inhibition of COX-2. Microparticles activated NF-,B, AP-1, p38, and JNK signaling in synovial fibroblasts. Inhibition of NF-,B, AP-1, and JNK signaling reduced the stimulatory effects. Arachidonic acid was transported from leukocytes to fibroblasts by microparticles. Arachidonic acid derived from microparticles was converted to PGE2 by synovial fibroblasts. Conclusion These results demonstrate that microparticles up-regulate the production of PGE2 in synovial fibroblasts by inducing COX-2 and mPGES-1. These data provide evidence for a novel mechanism by which microparticles may contribute to inflammation and pain in RA. [source] | ||||||||||