Theophylline inhibits NF-kappaB activation in human peripheral blood mononuclear cells

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-kappaB activation in mast cells. However, the action of theophylline on monocytes/macrophages and T cells is unknown.

We examined whether or not theophylline inhibits tumor necrosis factor (TNF)-alpha-induced activation of the nuclear transcription factor NF-kappaB, 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-alpha-induced NF-kappaB activation was evaluated by Western blotting, flow cytometry and chloramphenicol acetyltransferase (CAT) assaying. Expression of the IkappaBalpha protein was evaluated by Western blotting.

Western blotting demonstrated that theophylline inhibits NF-kappaB activation in U-937 and Jurkat cells and PBMC. Flow cytometry demonstrated that theophylline inhibits NF-kappaB activation in U-937 and Jurkat cells in a dose-related manner. CAT assaying indicated that NF-kappaB-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 IkappaBalpha protein.

These findings are consistent with the idea that theophylline suppresses the production of proinflammatory cytokines via inhibition of NF-kappaB activation through preservation of the IkappaBalpha protein in monocytes/macrophages and T cells.