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Mediators of Inflammation
Volume 2014 (2014), Article ID 279171, 18 pages
http://dx.doi.org/10.1155/2014/279171
Research Article

HO-1 Induction by CO-RM2 Attenuates TNF-α-Induced Cytosolic Phospholipase A2 Expression via Inhibition of PKCα-Dependent NADPH Oxidase/ROS and NF-κB

1Department of Physiology and Pharmacology and Health Aging Research Center, College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan 333, Taiwan
2Department of Anesthetics, Chang Gung Memorial Hospital at Linkou and College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan 333, Taiwan

Received 29 August 2013; Revised 14 November 2013; Accepted 22 November 2013; Published 29 January 2014

Academic Editor: Sunil Kumar Manna

Copyright © 2014 Pei-Ling Chi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Rheumatoid arthritis (RA) is characterized by chronic inflammatory infiltration of the synovium and elevation of proinflammatory cytokines. Cytosolic phospholipase A2 (cPLA2) is involved in the development of inflammatory diseases. Heme oxygenase-1 (HO-1) has been shown to possess anti-inflammatory properties. The objective of the study was to investigate the detailed mechanisms of TNF-α-induced cPLA2 expression and to determine whether carbon monoxide releasing molecule-2 (CO-RM2) suppresses TNF-α-induced expression of NF-κB-related proinflammatory genes, including cPLA2, via HO-1 induction in RA synovial fibroblasts (RASFs). Here, we reported that TNF-α-induced cPLA2 expression was mediated through TNFR1/PKCα-dependent signaling pathways, including NADPH oxidase (NOX) activation/ROS production and NF-κB activation. CO-RM2 significantly suppressed TNF-α-induced cPLA2 expression by inhibiting the ROS generation and the phosphorylation of NF-κB p65 and IKKα/β, but not the phosphorylation of p38 MAPK and JNK1/2. These results were further confirmed by a ChIP assay to detect the NF-κB DNA-binding activity. Our results demonstrated that induction of HO-1 by CO-RM2 exerted anti-inflammatory and antioxidant effects which were required in concert to prevent the activation of NF-κB leading to induction of various inflammatory genes implicated in the pathogenesis of RA.