| Summary: | <p>Abstract</p> <p>Background</p> <p>Extracts of the creosote bush, <it>Larrea tridentata</it>, have been used for centuries by natives of western American and Mexican deserts to treat a variety of infectious diseases and inflammatory disorders. The beneficial activity of this plant has been linked to the compound nordihydroguaiaretic acid (NDGA) and its various substituted derivatives. Recently, tetra-O-methyl NDGA or terameprocol (TMP) has been shown to inhibit the growth of certain tumor-derived cell lines and is now in clinical trials for the treatment of human cancer. In this report, we ask whether TMP also displays anti-inflammatory activity. TMP was tested for its ability to inhibit the LPS-induced production of inflammatory lipids and cytokines <it>in vitro</it>. We also examined the effects of TMP on production of TNF-α in C57BL6/J mice following a sublethal challenge with LPS. Finally, we examined the molecular mechanisms underlying the effects we observed.</p> <p>Methods</p> <p>RAW 264.7 cells and resident peritoneal macrophages from C57BL6/J mice, stimulated with 1 μg/ml LPS, were used in experiments designed to measure the effects of TMP on the production of prostaglandins, cytokines and chemokines. Prostaglandin production was determined by ELISA. Cytokine and chemokine production were determined by antibody array and ELISA.</p> <p>Western blots, q-RT-PCR, and enzyme assays were used to assess the effects of TMP on expression and activity of COX-2.</p> <p>q-RT-PCR was used to assess the effects of TMP on levels of cytokine and chemokine mRNA.</p> <p>C57BL6/J mice injected <it>i.p. </it>with LPS were used in experiments designed to measure the effects of TMP <it>in vivo</it>. Serum levels of TNF-α were determined by ELISA.</p> <p>Results</p> <p>TMP strongly inhibited the production of prostaglandins from RAW 264.7 cells and normal peritoneal macrophages. This effect correlated with a TMP-dependent reduction in levels of COX-2 mRNA and protein, and inhibition of the enzymatic activity of COX-2.</p> <p>TMP inhibited, to varying degrees, the production of several cytokines, and chemokines from RAW 264.7 macrophages and normal peritoneal macrophages. Affected molecules included TNF-α and MCP-1. Levels of cytokine mRNA were affected similarly, suggesting that TMP is acting to prevent gene expression.</p> <p>TMP partially blocked the production of TNF-α and MCP-1 <it>in vivo </it>in the serum of C57BL6/J mice that were challenged <it>i.p</it>. with LPS.</p> <p>Conclusion</p> <p>TMP inhibited the LPS-induced production of lipid mediators and several key inflammatory cytokines and chemokines, both <it>in vitro </it>and <it>in vivo</it>, raising the possibility that TMP might be useful as a treatment for a variety of inflammatory disorders.</p>
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