[Mechanisms for the regulatory effect of prostaglandin E2/prostaglandin E receptor 4 on high mobility group box-1 protein in lipopolysaccharide-induced sepsis in mouse peritoneal macrophage]

Abstract

To explore the effect of prostaglandin E2 (PGE2) on the expression of high mobility group box-1 protein (HMGB1) in peritoneal macrophages of septic mice and its possible mechanisms. Methods: The mouse peritoneal macrophages were isolated and cultured by conventional methods.The model of inflammation was established by using lipopolysaccharide (LPS) to incubate with mouse peritoneal macrophages. The PGE2, prostaglandin E receptor (EP) 4 agonist, EP4 RNAi, and DN.CREB inhibitory plasmid were used to interfere with the LPS-treated mouse peritoneal macrophage. The levels of HMGB1 was determined by Western blot. Results: Compared with LPS alone treatment, the expression of HMGB1 in peritoneal macrophages was increased obviously after 24 h by treatment with PGE2 and LPS, and it was also increased after the combined treatment of EP4 receptor agonist with LPS for 24 h (both P<0.05); compared with the PGE2+LPS treatment, the level of HMGB1 was decreased after knockdown of EP4 receptor expression (P<0.05); compared with EP4 receptor agonist +LPS treatment, there was no difference in HMGB1 levels in mice after the treatment with DN.CREB plasmid to suppress CREB function (P>0.05); compared with LPS alone treatment, the combined treatment of EP4 receptor agonist with LPS for 24 h could up-regulate the phosphorylation of epidermal growth factor receptor (EGFR) and protein kinase B (Akt) thr308 (P<0.05), which were blocked by EGFR inhibitor. Once Akt specific inhibitor was used before EP4 and LPS treatment, the expression of HMGB1 was declined (P<0.05). Conclusion: PGE2 can up-regulate the expression of HMGB1 in sepsis of peritoneal macrophages through EP4 receptor, which may be related to the activation of EGFR/PI3K/Akt signaling pathway.