Inhibition of nuclear factor kappa B and induction of apoptosis in T-lymphocytes by sulfasalazine

1 Chronic inflammatory diseases have been shown to be associated with NF-ka ppa B activation and impaired apoptosis of immune cells. The aim of the pre sent study was to investigate if sulfasalazine and its colonic metabolites 5-aminosalicylic acid (5ASA) and sulfapyridine affect NF-kappa B/Rel activa tion and viability of T-lymphocytes. 2 Sulfasalazine inhibits NF-kappa B/Rel activation in the murine T-lymphocy te cell line RBL5 using electrophoretic mobility shift assays. In transfect ion assays sulfasalazine treatment for 4 h inhibits kappa B-dependent trans cription with an IC50 value of similar to 0.625 mM. 3 Higher doses or prolonged treatment result in cell death of T-lymphocytes in a dose- and time-dependent manner. Cell death is caused by apoptosis as judged by DNA fragmentation, annexin V and Apo 2.7 staining. Induction of apoptosis is a fast event with 50% apoptotic cells after a 4 h incubation w ith 2.5 mM sulfasalazine. The ED50 value for apoptosis induction after 24 h treatment was similar to 0.675 mM. 4 In contrast, 5ASA and sulfapyridine neither inhibit NF-kappa B/Rel activa tion nor induce apoptosis in T-lymphocytes at doses up to 5.0 mM. 5 These results demonstrate that sulfasalazine, but not 5ASA or sulfapyridi ne, strongly inhibits NF-kappa B activation and potently induces apoptosis in T-lymphocytes. Inhibition of NF-kappa B/Rel activation and subsequent cl earance of activated T-lymphocytes by apoptosis might thus explain the bene ficial effects of sulfasalazine in the treatment of chronic inflammatory di sorders.