Inhibitory effect of linomide on lipopolysaccharide-induced proinflammatory cytokine tumor necrosis factor-alpha production in RAW264.7 macrophages through suppression of NF-κB, p38, and JNK activation

Linomide is an immunomodulator that can effectively inhibit the development of several autoimmune diseases in animal models. Previously, linomide was shown to influence macrophage function, although the mechanism was elusive. In this study, we investigated the effect of linomide on the macrophage inflammatory cytokine, tumor necrosis factor-alpha (TNF-α), production induced by lipopolysaccharide (LPS) in vitro on the murine macrophage cell line, RAW264.7. Linomide exposure reduced LPS-evoked TNF-α production in a dose-dependent manner. Gel shift and reporter gene analyses revealed linomide inhibited LPS-induced NF-κB binding to the NF-κB consensus oligonucleotide and NF-κB-mediated reporter gene expression. Immunoblot analysis showed that linomide inhibited phosphorylation of p38 kinase and c-jun N terminal kinase (JNK) in LPS-stimulated RAW264.7 cells. Taken together, these results suggest that linomide inhibits TNF-α production by suppressing the activation of NF-κB and mitogen-activated protein kinase (MAPK), which might, at least in part, contribute to the beneficial effects of linomide in the treatment of autoimmune diseases.