Cytokine synthesis in the liver of endotoxin-tolerant and normal rats during hemorrhagic shock

In the present study the effects of endotoxin tolerance on hemorrhagic shoc k were investigated with particular focus on hepatic alterations. The follo wing questions were addressed: (i) does hemorrhagic shock induce cytokine f ormation and heat shock response in the liver; and (ii) does endotoxin tole rance alter these reactions. Endotoxin tolerance was induced by repetitive daily injections of LPS for 5 days. Hemorrhagic shock was induced by hypovo lemia (MAP 35 +/- 5 mmHg). After 3 h, the animals were resuscitated by re-i nfusion of homologous blood, m-RNA was isolated from liver biopsies and the mRNA levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL- 6), interleukin-10 (IL-IO) and heat shock protein 70 (HSP-70) were determin ed by RT-PCR. TNF-alpha was measured by ELISA in serum samples and in the s upernatants of whole blood cultures. It was found that endotoxin tolerance reduced mortality caused by hemorrhagic shock from 80% to 20%. In parallel, TNF-alpha production in response to LPS in vivo and in vitro, was signific antly decreased. During hemorrhage and after resuscitation. increased mRNA levels were detected in hepatic biopsies for TNF-alpha, IL-6, IL-10 and HSP -70, with highest levels immediately after reinfusion. Endotoxin-tolerant r ats produced significantly lower levels of TNF-alpha, while no differences were found for IL-10 and HSP-70. Within 30 min after reperfusion, significa ntly higher levels of IL-6 mRNA were found in hepatic biopsies from toleran t rats; these differences disappeared 2 h after reperfusion.