Tumor necrosis factor (TNF) mediates a wide variety of disease states including
septic shock, acute and chronic
inflammation, and
cachexia. Recently, a multivalent guanylhydrazone (CNI-1493) developed as an inhibitor of macrophage activation was shown to suppress TNF production and protect against tissue
inflammation and
endotoxin lethality [Bianchi, M., Ulrich, P., Bloom, O., Meistrell, M., Zimmerman, G. A., Schmidtmayerova, H., Bukrinsky, M., Donnelley, T., Bucala, R., Sherry, B., Manogue, K. R., Tortolani, A. J., Cerami, A. & Tracey, K. J. (1995) Mol. Med. 1, 254-266, and Bianchi, M., Bloom, O., Raabe, T., Cohen, P. S., Chesney, J., Sherry, B., Schmidtmayerova, H., Zhang, X., Bukrinsky, M., Ulrich, P., Cerami, A. & Tracey, J. (1996) J. Exp. Med., in press]. We have now elucidated the mechanism by which
CNI-1493 inhibits macrophage TNF synthesis and show here that it acts through suppression of TNF translation efficiency.
CNI-1493 blocked neither the
lipopolysaccharide (LPS)-induced increases in the expression of TNF
mRNA nor the translocation of nuclear factor
NF-kappa B to the nucleus in macrophages activated by 15 min of LPS stimulation, indicating that
CNI-1493 does not interfere with early
NF-kappa B-mediated transcriptional regulation of TNF. However, synthesis of the 26-kDa membrane form of TNF was effectively blocked by
CNI-1493. Further evidence for the translational suppression of TNF is given by experiments using chloram-phenicol
acetyltransferase (CAT) constructs containing elements of the TNF gene that are involved in TNF translational regulation. Both the 5' and
3' untranslated regions of the TNF gene were required to elicit maximal translational suppression by
CNI-1493. Identification of the molecular target through which
CNI-1493 inhibits TNF translation should provide insight into the regulation of macrophage activation and mechanisms of
inflammation.