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

Abstract

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. CRHand interleukin-1␤ (IL-1␤)-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␤ 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␤. 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.Conclusion. 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.

Modulation of Orphan Nuclear Receptor NURR1 Expression by Methotrexate in Human Inflammatory Joint Disease Involves Adenosine A2A Receptor-Mediated Responses

“…Primary PsA synoviocyte cells were found to be morphogically homogenous fibroblast-like cells and did not react with specific Abs to the macrophage/monocyte Ag CD14. The immortalized normal human K4 IM synoviocyte cell line was grown as described previously (39,57,58). Primary human microvascular endothelial cells (BioWhittaker) were grown using EGM-MV BulletKit (BioWhittaker) (58).…”

“…The immortalized normal human K4 IM synoviocyte cell line was grown as described previously (39,57,58). Primary human microvascular endothelial cells (BioWhittaker) were grown using EGM-MV BulletKit (BioWhittaker) (58). All cells were grown in serum-free medium for 24 h before stimulation.…”

“…Cells were harvested after specific treatments, and nuclear protein extracts were prepared as described previously (31,58). SDS-PAGE was performed under reducing conditions on 10% polyacrylamide gels using concentrations of nuclear lysates as indicated.…”

“…Proinflammatory mediators (PGE 2 , IL-1␤, and TNF-␣) and growth factors (bFGF and VEGF) associated with joint inflammation (48,49,58) modulate NURR1 mRNA expression in normal human synoviocytes, primary RA and PsA synoviocytes, and vascular endothelium (32,39,64). Characteristic of immediate early response genes, the induction of NURR1 by such mediators exhibits a rapid turnover, with maximal NURR1 mRNA levels peaking at 1 h (32, 39).…”

Genetic analysis of CRHRA1 and CRHRA2 microsatellites and their association with rheumatoid arthritis in South Asian and Caucasian populations of the East Midlands, UK.

“…Locally, the CRH levels are increased in the joints of experimental arthritis (in Lewis rats) and in the synovium and synovial fluid of RA patients. 5,6 In situ CRH increases the cycloxygenase-2 derived prostaglandins E2 and E1 locally, thus promoting joint disease progression 7 and pain perception. 8 Baerwald et al (2000) 9 studied the genetic polymorphisms in the promoter region of the CRH gene among Caucasian (UK) and South African black RA patients and found that haplotype A2B1 was protective against developing RA in UK patients whereas allele A1B1 was positively associated with RA in the black South African RA patients (OR=1.78; CI= 1.01-3.15).…”