ENDOTOXIC-SHOCK LEADS TO APOPTOSIS IN-VIVO AND REDUCES BCL-2

Endotoxic shock results in multiple organ failure. At present, two dif ferent mechanisms of cellular destruction are of interest: necrosis an d apoptosis. Therefore, we started to investigate in pigs whether cell death due to apoptosis is involved in this pathophysiological process . DNA fragments were detected by ELISA specific for histone-associated DNA fragments in three different experimental settings. Pigs were lap arotomized followed by endotoxin infusion (ETOX group, n = 6), or lapa rotomized without endotoxin infusion (LAP group; n = 3) and compared w ith control animals (n = 3). 6 h of continuous endotoxin-infusion (5 m u g/kg/h) resulted in a significantly enhanced apoptosis in liver as c ompared with control animals (295 +/- 11%; p < .01), whereas in the LA P group, only a minor increase of 166 +/- 14% was detectable. In splee n of endotoxin-treated animals, an enhanced apoptosis of 150 +/- 12% c ompared with controls was shown in the ETOX group (p = .02), whereas k idney remained unaffected. These results were confirmed by agarose DNA gel electrophoresis. A typical DNA ladder was detected in liver and s pleen, but not in kidney of endotoxin-treated animals. Furthermore, im munohistochemical detection of DNA strand breaks with terminal deoxynu cleotidyl transferase in liver sections revealed a drastic increase of stained cells. The induction of apoptosis correlated with a reduced B ct-P content in endotoxin-treated animals. Our study demonstrates that 6 h of endotoxin treatment leads to apoptosis in liver and spleen in vivo, whereas kidney of endotoxin-treated animals remains unaffected. This process may be mediated by reduction of Bcl-2 by endotoxin treatm ent.