Role of ADAM‐17, p38 MAPK, Cathepsins, and the Proteasome Pathway in the Synthesis and Shedding of Fractalkine/CX3CL1 in Rheumatoid Arthritis

摘要: Objective To evaluate the mechanism of fractalkine (FKN)/CX3CL1 synthesis and shedding in rheumatoid arthritis synovial fibroblasts (RASFs) rat adjuvant-induced (AIA). Methods The effect tumor necrosis factor α (TNFα) and/or interferon-γ (IFNγ) on FKN human RASFs was determined over time by immunostaining, quantitative reverse transcription–polymerase chain reaction, Western blotting. The role protease enzymes signaling pathways evaluated using chemical inhibitors small interfering RNA (siRNA). activity 20S proteasome lysates DNA binding NF-κB/p65 nuclear fractions were evaluated. vivo relevance these findings examined AIA. Results In RASFs, stimulation with combination TNFα IFNγ induced cellular expression within 24 hours. Activation ADAM-17, but not ADAM-10, partly mediated proteolytic release soluble (sFKN) following TNFα/IFNγ for 24–72 Compared control siRNA, ADAM-17 siRNA markedly inhibited TNFα/IFNγ-induced sFKN production (by ∼33%). suppressed p38 MAPK, proteasome, or cathepsin inhibitor caspase 3 calpain. also correlated rapid degradation IκBα MAPK phosphorylation. In showed increased joints rats AIA, which phospho–p38 MAPK. Conclusion Our results provide new understanding cathepsins, pathway shedding. Regulating may suppress FKN-mediated inflammation tissue destruction.