PubMed · 10605207
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T Rousi, H Suoranta. 1996. [Sciatica].. https://pubmed.ncbi.nlm.nih.gov/10605207/
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Overexpression of the inducible cyclooxygenase (COX-2) and inducible NO synthase (iNOS) in activated brain macrophages (microglia) and astrocytes appears central to many neuroinflammatory conditions. 15-Deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)) is a ligand for the peroxisome proliferator-activated receptor (PPAR)gamma. It has been proposed as an inhibitor of microglial activation, based on the study of iNOS down-regulation in rodent microglia. Because iNOS induction after cytokine activation remains controversial in human microglia, we examined the effect of 15d-PGJ(2) and other PPAR agonists on human microglia and astrocytes, using COX-2 induction as an index of activation. We found that PPAR alpha ligands (clofibrate and WY14643) enhanced IL-1 beta-induced COX-2 expression in human astrocytes and microglia, while inhibiting IL-1 beta plus IFN-gamma induction of iNOS in astrocytes. This is the first description of an inhibition of iNOS uncoupled from that of COX-2. 15d-PGJ(2) suppressed COX-2 induction in human astrocytes. It prevented NF-kappa B binding to the COX-2 promoter through a new pathway that is the repression of NF-kappa Bp50 induction by IL-1 beta. In contrast, 15d-PGJ(2) increased c-Jun and c-Fos DNA-binding activity in astrocytes, which may result in the activation of other inflammatory pathways. In human microglia, no effect of 15d-PGJ(2) on COX-2 and NF-kappa Bp65/p50 induction was observed. However, the entry of 15d-PGJ(2) occurred in microglia because STAT-1 and c-Jun expression was modulated. Our data suggest the existence of novel pathways mediated by 15d-PGJ(2) in human astrocytes. They also demonstrate that, unlike astrocytes and peripheral macrophages or rodent brain macrophages, human microglia are not subject to the anti-inflammatory effect of 15d-PGJ(2) in terms of COX-2 inhibition.
Activation of T lymphocytes and their ensuing elaboration of proinflammatory cytokines, such as interferon (IFN)-gamma, represent a critical step in atherogenesis and arteriosclerosis. IFNgamma pathways also appear integral to the development of transplantation-associated arteriosclerosis (Tx-AA), limiting long-term cardiac allograft survival. Although disruption of these IFNgamma signaling pathways limits atherosclerosis and Tx-AA in animals, little is known about inhibitory regulation of proinflammatory cytokine production in humans. The present study investigated whether activators of peroxisome proliferator-activated receptor (PPAR)alpha and PPARgamma, with their known antiinflammatory effects, might regulate the expression of proinflammatory cytokines in human CD4-positive T cells. Isolated human CD4-positive T cells express PPARalpha and PPARgamma mRNA and protein. Activation of CD4-positive T cells by anti-CD3 monoclonal antibodies significantly increased IFNgamma protein secretion from 0 to 504+/-168 pg/mL, as determined by ELISA. Pretreatment of cells with well-established PPARalpha (WY14643 or fenofibrate) or PPARgamma (BRL49653/rosiglitazone or pioglitazone) activators reduced anti-CD3-induced IFNgamma secretion in a concentration-dependent manner. PPAR activators also inhibited TNFalpha and interleukin-2 protein expression. In addition, PPAR activators markedly reduced cytokine mRNA expression in these cells. Such antiinflammatory actions were also evident in cell-cell interactions with medium conditioned by PPAR activator-treated T cells attenuating human monocyte CD64 expression and human endothelial cell major histocompatibility complex class II induction. Thus, activation of PPARalpha and PPARgamma in human CD4-positive T cells limits the expression of proinflammatory cytokines, such as IFNgamma, yielding potential therapeutic benefits in pathological processes, such as atherosclerosis and Tx-AA.
A series of 4-(4-cycloalkyl/aryl-oxazol-5-yl)benzenesulfonamide derivatives were synthesized and evaluated for their abilities to inhibit cyclooxygenase-2 (COX-2) and cyclooxygenase-1 (COX-1) enzymes. In this series, substituent effects at the ortho position to the sulfonamide group on the phenyl ring were examined. Most substituents reduced or lost both COX-2 and COX-1 activities. In contrast, introduction of a fluorine atom preserved COX-2 potency and notably increased COX1/COX-2 selectivity. This work led to the identification of a potent, highly selective, and orally active COX-2 inhibitor JTE-522 [9d, 4-(4-cyclohexyl-2-methyloxazol-5-yl)-2-fluorobenzenesulfonamide], which is currently in phase II clinical trials for the treatment of rheumatoid arthritis, osteoarthritis, and acute pain.