Adenovirus binding to cultured synoviocytes triggers signaling through MAPK pathways and induces expression of cyclooxygenase‐2

Background Recombinant adenovirus can be administered in vivo to achieve transduction of a number of cell types including human synoviocytes. Immunogenicity of adenoviruses has limited their utility as vectors for gene delivery; however, specific mechanisms underlying the acute inflammatory response to adenovirus are not well understood. Activation of a number of signal transduction pathways occurs rapidly upon adenovirus binding to cell‐surface receptors. We investigated stimulated expression of mitogen‐activated protein kinases (MAPKs), cyclooxygenase‐2 (COX‐2) and prostaglandin E 2 (PGE 2 ) in human primary synovial fibroblasts to adenovirus expressing the E. coli β‐galactosidase gene. Methods Cultured rheumatoid synoviocytes were exposed to transduction‐competent Ad/RSVlacZ recombinant adenovirus or transduction‐incompetent (psoralen/UV‐irradiated) Ad/RSVlacZ. The effects on COX‐2 expression, PGE 2 levels and MAPK signaling in synoviocytes were assessed using a combination of reverse‐transcription polymerase chain reaction amplification and immunoblotting. Results Adenovirus treatment of synoviocytes increased levels of COX‐2 mRNA and protein as well as PGE 2 . Psoralen‐treated transcriptionally inactive adenovirus was equivalent to untreated adenovirus for early COX‐2 induction suggesting that viral genes were not required. Adenovirus treatment stimulated phosphorylation of ERK‐1/‐2, p38 MAPK, and JNK. Inhibition of the ERK and p38 MAPK pathways inhibited COX‐2 expression and PGE 2 production. Conclusions Taken together, these data demonstrate that a MAPK‐dependent increase in COX‐2 results in local prostaglandin production. These findings have clinical implications for use of adenovirus as vectors for in vivo gene delivery. Copyright © 2004 John Wiley & Sons, Ltd.