Changes in the inositol lipid signal system and effects on the secretion of TNF-alpha by macrophages in severely scalded mice.

摘要

AIM: In order to study the mechanism of abnormal macrophage (Mvarphi) function in pro-inflammatory cytokine changes after burn, the inositol lipid signal system and its role in tumour necrosis factor-alpha (TNF-alpha) secretion by peritoneal Mvarphis was observed in severely scalded mice. METHODS: Eighteen percent total body surface area (TBSA) full-thickness scalded mice were used as animal model in this experiment. Peritoneal Mvarphis stimulated by lipopolysaccharide in vitro were collected at different time intervals (0, 2, 6, 12, 24 and 48 after burn hour (PBH)), The activities of phosphatidylinositol-phospholipase C (PI-PLC), inositol-1, 4,5, -triphosphate (IP(3)), protein kinase C (PKC), diacylglycerol (DAG) and TNF-alpha and the level of Ca(2+) concentration in peritoneal Mvarphis were measured, and the effects of specific PKC inhibitor H-7 and calmodulin antagonist W-7 on the production of TNF-alpha were also observed. RESULTS: After scald, increased activities of TNF-alpha and PLC of Mvarphi were observed and peaked at 12 PBH. The activities of DAG and IP(3) and the concentration of Ca(2+) were markedly increased and reached their peaks at 24 PBH simultaneously. Membrane PKC activity was up-regulated after scald and showed a positive correlation with the change of DAG (r=0.83, P<0.05). There was also positive correlation between IP(3) and Ca(2+) activity (r=0.946, P<0.01). When 12 PBH was chosen as the time point for in vitro intervention with the pre-treatment by H-7, both membrane PKC and TNF-alpha activity decreased significantly. There was no obvious change of TNF-alpha activity with the application of W-7. CONCLUSIONS: These results indicated that the abnormal activity of TNF-alpha of Mvarphis might be regulated by the inositol lipid signal system following severe burn. The DAG-PKC signal pathway showed closer relationship than IP(3)-Ca(2+) in TNF-alpha production and could be the optimal target in the prevention and treatment of the systemic inflammatory response syndrome.