Lipopolysaccharides-induced interleukin-8 production is inhibited by antithrombin

Sepsis is one of the main causes of death in developed countries. It is commonly associated with disseminated intravascular coagulation (DIC), caused by consumption of coagulation factors and inhibitors such as antithrombin (AT) and the production of interleukin 6 (IL-6) and interleukin 8 (IL-8) have been shown to correlate positively with the severity of disease. Large doses of antithrombin (AT) reduce mortality and morbidity in septic patients and there is increasing evidence to suggest that AT has anti-inflammatory properties in addition to its anticoagulant properties. In our previous in vitro study, we have found that AT inhibits tissue factor and IL-6 production induced by lipopolysaccharides (LPS). In the present investigation, we have studied the effects of AT on LPS induced IL-8 production in three in vitro cellular systems. Citrated whole blood, human umbilical vein endothelial cells (HUVECs) and mononuclear cells (MNCs) were stimulated with LPS for 4–6 hours in the presence and absence of 0–40 IU/ml AT. IL-8 was measured by ELISA. In all three systems, AT dose-dependently inhibited IL-8 production, with greatest inhibition (98.7 ± 5.2% at 40 IU/ml) observed for the whole blood system and the least inhibition seen with MNCs (8.7 ± 21.7% at 40 IU/ml). RNA extraction of time course whole blood experiment followed by the detection of mRNA specific for IL-8 showed that in the absence of AT, mRNA for IL-8 was apparent after 30 min incubation with LPS. However, the level of IL-8 mRNA was found to decrease with increasing concentrations of AT. These results imply the inhibition of IL-8 antigen production by AT is due to the suppression of mRNA and indicated that the anti-inflammatory activity of AT also extends to the inhibition of IL-8, an important cytokine implicated in neutrophil migration.