RT Journal Article SR Electronic T1 Transforming growth factor β1 and laminin-111 cooperate in the induction of interleukin-16 expression in synovial fibroblasts from patients with rheumatoid arthritis JF Annals of the Rheumatic Diseases JO Ann Rheum Dis FD BMJ Publishing Group Ltd and European League Against Rheumatism SP 270 OP 275 DO 10.1136/ard.2008.091116 VO 69 IS 01 A1 K Warstat A1 M Hoberg A1 M Rudert A1 S Tsui A1 T Pap A1 B Angres A1 M Essl A1 T J Smith A1 W W Cruikshank A1 G Klein A1 S Gay A1 W K Aicher YR 2010 UL http://ard.bmj.com/content/69/01/270.abstract AB Objectives: In synovial tissues of patients with rheumatoid arthritis (RA), strong expression of laminins and integrins co-localises with increased expression of inflammatory cytokines. Synovial fibroblasts (SF) contribute to the pathogenesis of RA through increased expression of cytokines and chemoattractant factors, one of which is interleukin-16 (IL16). A study was undertaken to investigate the regulatory pathways of IL16 in SF from patients with RA (RA-SF) and osteoarthritis (OA-SF).Methods: SF were seeded in laminin-coated flasks and activated by the addition of cytokines. The expression of IL16 was investigated by quantitative RT-PCR, immunoblotting and ELISA; its biological activity was determined by a cell migration assay. Cell–matrix interactions were investigated by cell binding and attachment assays. Relevant intracellular signalling pathways were studied by immunoblotting and with pharmacological blocking reagents.Results: Stimulation of SF with transforming growth factor β1 (TGF-β1) and growth on laminin-111 (LM-111) significantly increased the expression of IL16. Binding to LM-111 induced significantly more IL16 mRNA in RA-SF than in OA-SF (p<0.05). The IL16 cytokine was detected in supernatants of TGF-β1-activated and in LM-111+TGF-β1-activated RA-SF (38 to 62 pg/ml), but not in supernatants of OA-SF. This IL16 regulation involved p38MAPK, ERK1/2 and SMAD2 signalling, but not NFκB.Conclusions: Binding of RA-SF to LM-111 in the presence of TGF-β1 triggers a significant IL16 response and thus may contribute to the infiltration of CD4+ lymphocytes into synovial tissues. This mode of IL16 induction represents a novel pathway leading to IL16 production in RA-SF but not in OA-SF, which operates independently of NFκB signalling.