Synergism Between Taurine and Dexamethasone in Anti-inflammatory Response in LPS-Activated Macrophages.

Abstract

The aim of the present study is to examine the potential effect of dexamethasone (DEX) and taurine (TAU) on endoplasmic reticular stress (ERS) and inflammation. The macrophages were pre-treated with DEX or TAU, and the level of ERS and pro-inflammatory response was evaluated in LPS-activated macrophages. The expression of ERS marker proteins (GRP78 and CHOP) and the pro-inflammatory cytokines (IL-1β and IL-6) was analyzed by immunoblotting and ELISA of LPS-induced macrophages. At lower concentrations (<50nM), DEX alone reduced the levels of ERS and pro-inflammatory markers. Similarly, TAU reduced the expression of LPS-induced ERS and pro-inflammatory markers. When treated with a combination of DEX and TAU, however, the macrophages showed even a greater level of reduction in ERS and pro-inflammatory responses. The RT-qPCR data indicate that the reduction of ERS markers is caused by the inhibition of their own transcriptional expression. The significant level of reduction can be interpreted as a strong synergistic effect (p<0.01). In summary, the results strongly indicate that a single pre-treatment of DEX or TAU may attenuate ERS and inflammation in LPS-induced macrophages at the concentrations tested in this study. Most importantly, concurrent treatment of macrophages by both agents reduced the level of ERS and pro-inflammatory cytokines in a synergistic fashion.