Effects of polymyxin B on LPS-induced activation of NF-κB in pulmonary alveolar macrophages
YANG Jian hong, YIN Wen, YUAN Jing, LI Yue cai Department of Emergency, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
AIM: To observe effects of polymyxin B (PMB) on LPS induced activation of NF κB of pulmonary alveolar macrophages(PAMs) and explore the possible anti inflammation efficiency of PMB. METHODS: Rat PAMs were isolated and cultured. The PAMs were divided into 3 groups, namely, normal control group (PAMs+normal solution), LPS stimulation group (PAMs+10 mg/L LPS) and PMB interference group(after PMB treatment for 30 min, using LPS stimulation). The PAMs were fixed respectively at 0,15,30,60,120 and 240 min after stimulation. Nucleoprotein was extracted from cultured PAMs and culture supernatant of the PAMs was collected. The expression of IKK β mRNA in the PAMs, NF κB activity in PMB nucleoprotein extractive, TNF α content in culture supernatant of the PAMs were detected by in situ hybridization (ISN), electrophoretic mobility shift assay (EMSA) and ELISA, respectively. RESULTS: IKK β mRNA level in LPS group increased at 15 min, reached the peak at 30 min, while IκB α level turned out contrary to IKK β mRNA level. The peak of NF κB activity appeared at 60～120 min after stimulation was significantly higher than those of pre stimulation and normal control group ( P 0.01). In PMA interference group, NF κB activity and TNF α level were markedly lower than those in LPS stimulation group ( P 0.01). The lowest level of IκB α was notably higher than that in LPS stimulation group, while the peak of IKK β mRNA was obviously lower than that in LPS stimulation group ( P 0.01). CONCLUSION: LPS can induce IKK β and NF κB activation, IκB α degradation, accelerate TNF α release, but PMB can counteract those effects induced by LPS stimulation.