Inhibition of cytokine gene expression by sodium salicylate in a macrophage cell line through an NF-kappa B-independent mechanism

Macrophage-derived cytokines and chemokines are involved at multiple steps of immune and inflammatory responses, and the transcriptional factor NF-kap pa B appears to play a pivotal role in their coordinated upregulation, The anti-inflammatory agents salicylates have been proposed to act in part by i nhibiting NF-kappa B, We have therefore studied the effects of sodium salic ylate on lipopolysaccharide (LPS)-induced kappa B-binding activity and on c ytokine and chemokine gene expression in the RAW264.7 murine macrophage cel l line and compared them to those of an established NF-kappa B inhibitor, p yrrolidine dithiocarbamate (PDTC), PDTC (100 mu M) completely abrogated LPS -induced kappa B-binding activity and also profoundly inhibited the inducti on of interleukin 1 alpha (IL-1 alpha), IL-1 beta, IL-6, IL-10, granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating facto r, and MCP-I and, to a lesser extent, leukemia inhibitory factor, RANTES, a nd IL-1Ra, In contrast, sodium salicylate (15 to 20 mM) had no effect on NF -kappa B activation but, nevertheless, suppressed several LPS-induced cytok ine and chemokine genes to a degree similar to that obtained with PDTC. How ever, compared to PDTC, sodium salicylate caused significantly less inhibit ion of IL-1Ra and IL-10 gene expression after LPS stimulation. Neither LPS- induced MIP-1 alpha, MIP-1 beta, nor MIP-2 was significantly affected by PD TC or sodium salicylate, demonstrating that NF-kappa B is dispensable for t he transcriptional regulation of these genes by LPS, In summary, these resu lts suggest that both NF-kappa B-dependent and NF-kappa B-independent pathw ays are necessary for the induction by LPS of a complex cytokine and chemok ine response. In the RAW264.7 macrophage cell line, suprapharmacological co ncentrations of sodium salicylate exert a potent inhibitory effect on LPS-i nduced cytokine gene induction but appear to accomplish this by interfering with NF-kappa B-independent pathways of activation.