Inhibition of NF-kB and induction of apoptosis by sulphasalazine

摘要

Objective: Transcription factors of the NF-KB/Rel family are important regulators of the immune response and apoptosis. Sulphasalazine (SS) and its moiety 5-aminosalicylic acid (5-ASA) have long been known for their beneficial effects in the treatment of USD. However, their molecular mode of action is not understood.Aims: The purpose of this study was to investigate whether SS or 5-ASA affect NF-KB/Rel activation or T-cell viability.Methods and results: SS inhibits NF-kB activation in T-lymphocytes using elec-trophoretic mobility shift and transfection assays. In immune complex assays, SS inhibits the NF-kB activating kinases (IKKa and IKKfl) directly, most likely by competitive binding to the ATP binding site. Higher doses or prolonged incubation results in apoptosis of T-lymphocytes as determined by DNA fragmentation, annexin V and Apo 2.7 staining. SS-induced apoptosis is triggered by collapse of the mitochondrial transmembrane potential, which leads to cytochrome c release and activation of caspase-3 and downstream substrates. However, the pan-caspase inhibitor Z-VAD.fmk fails to inhibit SS-induced apoptosis. SS stimulates mito-chondrio-nuclear translocation of the novel apoptogenic factor A1F (apoptosis inducing factor) and triggers caspase-independent apoptosis.