A Rapid and Sustained Increase in Neutrophil Elastase Levels Correlates Temporally with Decreased Coagulation Factor Activity during E.coli-Sepsis in Baboons.

Abstract

Infection is the most common pathology resulting in disseminated intravascular coagulation (DIC) in humans. Disturbances of the cell interactions between neutrophils and endothelial cells are an integral part of the pathophysiology of E.coli-sepsis. Although neutrophil elastase (NE) is required for the destruction of gram negative bacteria, dysregulated NE activity towards coagulation factors may contribute to the coagulopathies that accompany infections if its activity is not properly regulated by alpha-1-protease inhibitor (A1PI). The temporal relationships between these variables were studied in plasma samples from three baboons before and after infusion of either two sublethal doses (2.50x106 cfu/kg and 1.10x108 cfu/kg) or a lethal dose (6.50x108 cfu/kg) of E.coli. In comparison to pre-infusion levels, the A1PI/NE complex levels increased by up to 17-fold after 2hrs and remained 6-fold above baseline after 53hrs as the amount of E.coli was increased. In contrast, the A1PI activity and specific activity both decreased by up to 30% during the 2–6hrs following the lethal dose of E.coli. Large transient decreases, of between 60–96%, in the factor V and VIII activity and fibrinogen levels occurred only during the 2–6hrs following infusion of the lethal dose. In addition, there was a 70–80% decrease in the factor II, VII, IX, and X clotting activity after 6–24hrs as the dose of E.coli was increased. In conclusion, there is a temporal association between the changes in A1PI activity, the appearance of the A1PI/NE complex, and the decrease of coagulation factor activity during E.coli-sepsis in baboons. Further, the sustained elevation of the A1PI/NE complexes beyond 48hrs, even after sublethal challenge with E.coli, indicates that a persistent increase in the neutrophil activity occurs as part of the inflammatory response to bacterial infection in this animal model. This study demonstrates that the neutrophil/endothelial interaction continues far beyond the first margination stage into the second ischemia/reperfusion stage during E.coli-sepsis. The results raise the possibility that clotting factor degradation/inactivation by NE as well as consumption via the coagulation cascade occurs following infusion of sublethal and lethal doses of E.coli.