Theophylline Inhibits NF-κB Activation in Human Peripheral Blood Mononuclear Cells

Abstract

Background: Theophylline not only dilates the bronchi, but also modulates the production of proinflammatory cytokines and inhibits inflammation. Theophylline exerts an antiinflammatory effect on allergic inflammation through inhibition of NF-ĸB activation in mast cells. However, the action of theophylline on monocytes/macrophages and T cells is unknown. Methods: We examined whether or not theophylline inhibits tumor necrosis factor (TNF)-α-induced activation of the nuclear transcription factor NF-ĸB, a factor that is essential for the expression of proinflammatory cytokines, in human monocytic U-937 cells, a T cell line (Jurkat) and peripheral blood mononuclear cells (PBMC). The inhibitory effect of theophylline on TNF-α-induced NF-ĸB activation was evaluated by Western blotting, flow cytometry and chloramphenicol acetyltransferase (CAT) assaying. Expression of the IĸBα protein was evaluated by Western blotting. Results: Western blotting demonstrated that theophylline inhibits NF-ĸB activation in U-937 and Jurkat cells and PBMC. Flow cytometry demonstrated that theophylline inhibits NF-ĸB activation in U-937 and Jurkat cells in a dose-related manner. CAT assaying indicated that NF-ĸB-dependent reporter gene expression is inhibited in U-937 cells pretreated with theophylline. Western blotting of cytoplasmic extracts of U-937 cells revealed that this inhibition was linked to theophylline-induced preservation of expression of the IĸBα protein. Conclusions: These findings are consistent with the idea that theophylline suppresses the production of proinflammatory cytokines via inhibition of NF-ĸB activation through preservation of the IĸBα protein in monocytes/macrophages and T cells.