Up-regulation of Prostaglandin E2 Synthesis by Interleukin-1β in Human Orbital Fibroblasts Involves Coordinate Induction of Prostaglandin-Endoperoxide H Synthase-2 and Glutathione-dependent Prostaglandin E2 Synthase Expression

Abstract

Prostaglandin E 2 (PGE 2 ) production involves the activity of a multistep biosynthetic pathway. The terminal components of this cascade, two PGE 2 synthases (PGES), have very recently been identified as glutathionedependent proteins. cPGES is cytoplasmic, apparently identical to the hsp90 chaperone, p23, and associates functionally with prostaglandin-endoperoxide H synthase-1 (PGHS-1), the constitutive cyclooxygenase. A second synthase, designated mPGES, is microsomal and can be regulated. Here we demonstrate that mPGES and PGHS-2 are expressed at very low levels in untreated human orbital fibroblasts. Interleukin (IL)-1␤ treatment elicits high levels of PGHS-2 and mPGES expression. The induction of both enzymes occurs at the pretranslational level, is the consequence of enhanced gene promoter activities, and can be blocked by dexamethasone (10 nM). SC58125, a PGHS-2-selective inhibitor, could attenuate the induction of mPGES, suggesting a dependence of this enzyme on PGHS-2 activity. IL-1␤ treatment activates p38 and ERK mitogen-activated protein kinases. Induction of both mPGES and PGHS-2 was susceptible to either chemical inhibition or molecular interruption of these pathways with dominant negative constructs. These results indicate that the induction of PGHS-2 and mPGES by IL-1␤ underlies robust PGE 2 production in orbital fibroblasts.

IL-1β Induces IL-6 Expression in Human Orbital Fibroblasts: Identification of an Anatomic-Site Specific Phenotypic Attribute Relevant to Thyroid-Associated Ophthalmopathy

“…The effect was intermediate at a cytokine concentration of 5 ng/ml and was near-maximal at 10 ng/ml. Thus, the dose dependency is consistent with other established actions of IL-1␤ in orbital fibroblasts (32).…”

“…Several of these inductions are mediated through the activation of p38 and ERK 1/2 MAPK pathways (32). Treatment with IL-1␤ (10 ng/ml) resulted in the very rapid phosphorylation of p38 (Fig.…”

“…The amplified fragment was sequenced and subcloned from the pCR2.1 TOPO vector (Invitrogen Life Technologies) into a promoterless pGL2-luciferase reporter vector (Promega). This was used to transiently transfect subconfluent fibroblast monolayers as described previously (32). Briefly, cultures were allowed to proliferate to 80 -90% confluence in medium containing 10% FBS.…”

Aberrant Expression of the Insulin-Like Growth Factor-1 Receptor by T Cells from Patients with Graves’ Disease May Carry Functional Consequences for Disease Pathogenesis

“…Cytokines and lipid mediators, synthesized by infiltrating T lymphocytes, monocytes, and mast cells, drive tissue remodeling, including the accumulation of hyaluronan, an abundant nonsulfated glycosaminoglycan (25,26). The unique phenotype of orbital fibroblasts and their exaggerated responses to cytokines such as IL-1␤ represent the basis for disease susceptibility of these tissues (25,(27)(28)(29)(30)(31). Why immunocompetent cells are recruited to the orbit in TAO remains uncertain.…”

Potential Role of Microsomal Prostaglandin E Synthase-1 in Tumorigenesis

“…A recent gene targeting study of mPGES-1 has shown that PGE 2 production by lipopolysaccharide-stimulated peritoneal macrophages depends almost entirely on this enzyme (29). Induced expression of mPGES-1 is regulated by the NF-IL-6 pathway (29) or the mitogen-activated protein kinase pathway (30), the latter of * This work was supported by a Showa University grant-in-aid for Innovative Collaborative Research Projects and a Special Research grant-in-aid for Development of Characteristic Education from the Japanese Ministry of Education, Culture, Sports, Science and Technology of Japan. The costs of publication of this article were defrayed in part by the payment of page charges.…”