Chloromethyl ketones inhibit interleukin-12 production in mouse macrophages stimulated with lipopolysaccharide

Interleukin-12 (IL-12) plays a pivotal role in the development of;T-helper type 1 (Th1) immune response, which may be involved in the pathogenesis of chronic inflammatory autoimmune disorders. In this study, we investigated t he effects of N-alpha-tosyl-L-phenylalanine chloromethyl ketone (TPCK) and N-alpha-tosyl-L-lysine chloromethyl ketone (TLCK), serine protease inhibito rs, on the production of IL-12 from macrophages stimulated with lipopolysac charide (LPS). TPCK and TLCK potently inhibited this LPS-induced IL-12 prod uction in a dose-dependent manner. The effect of TPCK and TLCK on the IL-12 p40 promoter activation was analyzed by transfecting monocytic RAW264.7 ce lls with p40 promoter-reporter constructs. The repressive effect maps to a region in the p40 promoter containing a binding site for NF kappa B (p40-ka ppa B). A. linker scan mutant of the p40-kappa B site abrogates the inhibit ory effect on the p40 promoter, confirming the functional relevance of the NF kappa B site. Our results show that TPCK and TLCK inhibit NF kappa B-med iated IL-12 production in macrophages. (C) 1999 Elsevier Science B.V. All r ights reserved.