Cyclooxygenase 2-derived prostaglandin E2 production by corticotropin-releasing hormone contributes to the activated cAMP response element binding protein content in rheumatoid arthritis synovial tissue.
OBJECTIVE
To determine a mechanism by which corticotropin-releasing hormone (CRH) promotes human inflammatory joint disease progression.


METHODS
An ex vivo synovial tissue culture system was established to investigate the functional properties of CRH at peripheral sites of inflammation. CRH- and interleukin-1 beta (IL-1 beta)-induced prostaglandin E(2) (PGE(2)) production from 10 fresh rheumatoid arthritis (RA) synovial tissue (ST) explants was quantified using a competitive enzyme-linked immunosorbent assay. Modulation of PGE(2) levels was further examined following selective and nonselective cyclooxygenase 2 (COX-2) inhibition. Nuclear extracts were analyzed by electrophoretic mobility shift assays to determine functional cAMP response element binding protein (CREB) activity in response to CRH and PGE(2) in isolated primary synovial cell populations. Western blot analysis measured levels of total and activated (phosphospecific) CREB/activating transcription factor (ATF) family members prior to and following stimulation.


RESULTS
CRH, in a time- and dose-dependent manner, significantly (P = 0.022) up-regulated PGE(2) production from 10 fresh RA ST explants. Costimulation of RA ST with CRH and IL-1 beta significantly augmented (P = 0.036) the effects on PGE(2) production additively over 24 hours. We demonstrated that selective COX-2 inhibitors prevent the induction of PGE(2) by both CRH and IL-1 beta. Further, we provided evidence that CRH and PGE(2) signal through the induction of CREB and phosphorylated CREB/ATF family members in RA ST and in isolated primary RA cell populations.


CONCLUSIONS
Our findings underscore the pathogenic role that CRH may play in modulating inflammatory joint disease and establish the CREB/ATF family of transcription factors as principal effector molecules of proinflammatory mediator action in RA.
McEvoy
Alice N
AN
Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland.
Bresnihan
Barry
B
FitzGerald
Oliver
O
Murphy
Evelyn P
EP
D051696:Activating Transcription Factors; D001172:Arthritis, Rheumatoid / Q000276:immunology / Q000378:metabolism*; D001798:Blood Proteins / Q000378:metabolism; D002478:Cells, Cultured; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D015232:Dinoprostone / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D007375:Interleukin-1 / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008565:Membrane Proteins; D010766:Phosphorylation / Q000187:drug effects; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D013583:Synovial Membrane / Q000166:cytology / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
D051696:Activating Transcription Factors; D001798:Blood Proteins; D017362:Cyclic AMP Response Element-Binding Protein; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D018836:Inflammation Mediators; D007375:Interleukin-1; D007527:Isoenzymes; D008565:Membrane Proteins; D014157:Transcription Factors; D003346:Corticotropin-Releasing Hormone; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone