Anti-inflammation Mechanism of Polymyxin B
YANG Jian-hong,YIN Wen,XIE Xin. Department of Emergency,Wuhan General Hospital,Guangzhou Command,PLA,Wuhan Hubei 430070,China
Objective To observe the pathway changes of nuclear factor kappa B (NF-κB) after rat pulmonary alveolar macrophages (PAM) were treated with LPS and polymyxin B (PMB). Methods Wistar rat PAM were isolated and cultured, then treated with normal solution as normal control group, LPS as LPS stimulation group and LPS+PMB as interference group. PAM were fixed respectively at 0, 15, 30, 60, 120 and 240 min after stimulation. IKK-β mRNA expression in PAM by in situ hybridization, NF-κB activity in nucleoprotein extracted from PMB by electrophoretic mobility shift assay (EMSA), IκB-α and TNF-α content in culture supernatant by ELISA were detected. Results In LPS group, IKK-βmRNA level increased at 15 min, reached the peak at 30 min and decreased at 60 min, while IκB-α level turned out contrary to IKK-βmRNA level; NF-κB activity peaked at 60 min, and started to decrease at 120 min, significantly higher than that before stimulation and of normal control group (P0.01); TNF-α level reached the peak at 60 min, started to increase at 30 min and got back to the level before stimulation at 120-240 min. In interference group, NF-κB activity and TNF-α level were markedly lower than those in LPS stimulation group (P0.01);The lowest level of IκB-α was notably higher and the peak of IKK-β mRNA was obviously lower than that in LPS stimulation group (P0.01). Conclusion LPS can induce IKK-β and NF-κB activation, IκB-α degradation and accelerated TNF-α release, but PMB can counteract those effects.