The regulatory effect of ERK1/2 signal pathway on production of TNFα induced by LPS in mice Kupffer cells

Objective: To study the rule of ERK1/2 activity and regulative effect of ERK1/2 pathway on the production of pro inflammatory cytokine TNFα in mice Kupffer cells (mKC) induced by LPS, and to exploring novel methods to prevent and treat clinical patients of endotoxemia. Methods: Immunoprecipitate kinase assay and Western blotting analysis were used to detect the phosphorylated ERK1/2 kinase activity in mKC stimulated by LPS, and ELISA was used to study the effect of ERK1/2 signaling cascade on LPS induced TNFα production in mKC. Results: In mKC, LPS treatment resulted in transient and rapid increase of kinase activity of ERK1/2 that phosphorylated their specific substrate ELK 1, with maximal value at 30 minutes and a return near to baseline within 2 hours, and LPS induced ERK1/2 activity from LPS concentration of 10 pg/ml to the top activity at 100 ng/ml . No activity was observed in unstimulated mKC. Inhibition of the ERK1/2 pathway using the specific ERK 1/2 signal pathway inhibitor PD98059 caused a marked and concentration dependent reduction of TNFα production. Conclusions: The results show that LPS can markedly activate ERK1/2 pathway in mKC. PD98059 causes a significant and concentration dependent reduction of TNFα production. ERK1/2 may be a novel target to treat clinical patient of endotoxemia.