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 ERK1/2 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.

The morbidity and mortality of myeloproliferative neoplasms (MPNs) are primarily caused by arterial and venous complications, progression to myelofibrosis, and transformation to acute leukemia. However, identifying molecular-based biomarkers for risk stratification of patients with MPNs remains a challenge. We have previously shown that interferon regulatory factor-8 (IRF8) and IRF4 serve as tumor suppressors in myeloid cells. In this study, we evaluated the expression of IRF4 and IRF8 and the JAK2V617F mutant allele burden in patients with MPNs. Patients with decreased IRF4 expression were correlated with a more developed MPN phenotype in myelofibrosis (MF) and secondary AML (sAML) transformed from MPNs versus essential thrombocythemia (ET). Negative correlations between the JAK2V617F allele burden and the expression of IRF8 (P < 0.05) and IRF4 (P < 0.001) and between white blood cell (WBC) count and IRF4 expression (P < 0.05) were found in ET patients. IRF8 expression was negatively correlated with the JAK2V617F allele burden (P < 0.05) in polycythemia vera patients. Complete response (CR), partial response (PR), and no response (NR) were observed in 67.5%,10%, and 22.5% of ET patients treated with hydroxyurea (HU), respectively, in 12 months. At 3 months, patients in the CR group showed high IRF4 and IRF8 expression compared with patients in the PR and NR groups. In the 12-month therapy period, low IRF4 and IRF8 expression were independently associated with the unfavorable response to HU and high WBC count. Our data indicate that the expression of IRF4 and IRF8 was associated with the MPN phenotype, which may serve as biomarkers for the response to HU in ET.
Biomarkers ; Humans ; Hydroxyurea/therapeutic use* ; Interferon Regulatory Factors/genetics* ; Janus Kinase 2/genetics* ; Leukemia, Myeloid, Acute/genetics* ; Mutation ; Phenotype ; Primary Myelofibrosis/genetics* ; Thrombocythemia, Essential/genetics*