Effect Of Kupffer Cells Blockade On Activation Of MAPK And STAT Induced By Lipopolysaccharide

Objective: Kupffer cells activated by Lipopolysaccharide(LPS)produce considerable amount of pro-inflammatory cytokines such as TNF-α, reactive oxygen species(ROS), by one way, which activated mitogen-activated protein kinase(MAPK) and JAK/STAT, leading to liver injury. Gadolinium chloride(GdCl₃)attenuates LPS-induced hepatic injury by inactivating KCs. The mechanism of causing the liver protection, however, whether or not by which GdCl₃ regulates MAPKs and JAK/STAT signal transduction pathways is poorly defined. Using the mouse model of endotoxemia, we study the effect of KCs blockade on activation of MAPKs and JAK/STAT signal transduction pathways induced by LPS.Methods:â… .GdCl₃(10mg/kg) or the same volume of 0.9% Sodium Chloride was continually injected into tail vein at 48h and 24h before Galn/LPS(13mg/3μg/mouse) intraperitoneal injection. The blood was collected from angular vein and liver was extirpated with carbrital anaesthesia after LPS or 0.9% Sodium Chloride injected at 0.5h,1h,1.5h and 6h for assaying ALT,GSH,MDA and TNF-α.â…¡.GdCl₃(10mg/kg) or the same volume of 0.9% Sodium Chloride was continually injected into tail vein at 48h and 24h before LPS(5mg/kg) intraperitoneal injection. The liver was extirpated with carbrital anaesthesia after LPS or 0.9% Sodium Chloride injected at 0.5h,2h and 6h, and the proteins extracted from livers was assayed for the phosphorylation level of MEK1/2,ERK1/2,p38MAPK,STAT1 and STAT3 by western blotting.Results:Galn/LPS-induced acute liver injury was attenuated significantly by GdCl₃ pretreatment. The plasma ALT activity and the content of MDA and TNF-αin liver decreased remarkably by GdCl₃ preteatment while the content of GSH in liver increased significantly. The phosphorylation of MEK1/2,ERK1/2,p38MAPK,STAT1 and STAT3 in liver were enhanced significantly campared with control after LPS stimulation while GdCl₃ preteatment inhibited the phosphorylation of these signal proteins.Conclusion: GdCl₃ preteatment significantly inactived KCs and decreased TNF-αand ROS induced by LPS, therefore attenuated liver injury. GdCl₃ blocking KCs may regulate MAPK and JAK/STAT signal transduction pathways in liver.