Pro-inflammatory cytokines, such as the IL-18-induced inflammatory
response and associated damage in fibroblast-like synoviocytes (FLS),
play an important role in the pathogenesis of rheumatoid arthritis
(RA). Roflumilast, an inhibitor of phosphodiesterase-4 (PDE-4), has
been licensed for the treatment of chronic obstructive pulmonary disease
(COPD). However, it is unknown whether roflumilast possesses a protective
effect against the IL-18-induced inflammatory response in FLS. We
found that roflumilast attenuated IL-18-induced oxidative stress by
reducing the production of reactive oxygen species and malondialdehyde
(MDA) in MH7A fibroblast-like synoviocytes (FLS). Additionally, roflumilast
prevented IL-18-induced expressions and secretions of pro-inflammatory
cytokines such as IL-6, IL-8, and TNF-α. Importantly, we found
that roflumilast inhibited IL-18-induced expressions of chemokines
such as CCL5, CXCL9, and CXCL10. Further, roflumilast inhibited the
expression of extracellular matrix degradative enzymes, such as matrix
metalloproteinase-3 (MMP-3) and MMP-13. Mechanistically, we found
that roflumilast suppressed the activation of the transcriptional
factor AP-1 and NF-κB. Our results suggest that roflumilast
might be a potential therapeutic agent for the treatment of RA.