Endotoxin und Interferon-y aktivieren unterschiedliche MAP Kinasen in neutrophilen Granulozyten Endotoxin and interferon-y activate different MAP kinases in neutrophil granulocytes

Purpose of Study: During sepsis reduced neutrophil (PMN) apoptosis leads to the accu­ mulation of PMN at the site of inflammation, thus enhancing tissue destruction through the release of toxic metabolites. Proinflammatory mediators such as endotoxin (LPS) or interferon-y (IFN-y) reduce PMN apoptosis through the activation of protein kinases. The role of the mitogen-activated protein kinases (MAPK) P38 and ERK in the regulation of PMN apoptosis during sepsis was studied. Methods: PMN from 13 patients with severe sepsis (APACHE II 23.1±5.6 points) and from 9 healthy controls were isolated from heparinized peripheral blood and incubated for 1 h with the broad kinase inhibitor herbimycin (1 f.LM), the P38 specific inhibitor SB203580 (5 f.LM), or the ERK specific inhib­ itor PD98059 (50 f.LM). Subsequently, cells were stimulated with LPS (1 J,lg/mL) or IFN-y (100 ng/mL) or left untreated for an additional 15 h. Apoptosis was measured in FACS after PI staining. Results: Spontaneous PMN apoptosis was reduced in patients with sep­ sis (-39.40/0,P<0.05) compared to controls. Stimulation with LPS or IFN-y reduced PMN apoptosis in healthy controls as well as in patients with sepsis which could be reconsti­ tuted by inhibition with herbimycin. Inhibition of ERK kinases only elevated the LPS-re­ duced apoptosis (94±9.00/0), whereas inhibition of P38 only reconstituted the IFN-y-me­ diated effect (102±4.10/0). Conclusion: The results presented here demonstrate that the re­ duction of spontaneous PMN apoptosis through inflammatory stimuli is transmitted by different MAPKs. Therefore, the inhibition of single kinases to counterregulate sepsis in­ duced inhibition of PMN apoptosis is likely to remain unsuccessful.