The function of granulocytes and alveolar macrophages following a single dose of endotoxin in rabbits. Effects of methylprednisolone

Neutrophils express tissue factor in a monkey model of sepsis

BACKGROUND

Although tissue factor (TF) is involved in hemostasis, thrombogenesis, inflammation, and cellular immune response, its source in sepsis remains controversial. Recently, we found that, in addition to monocytes and endothelial cells, neutrophils may express TF in a rabbit model. The purpose of this study was to determine whether neutrophils could be a source of TF in a monkey model of sepsis.

METHODS

TF messenger RNA (mRNA) and protein in neutrophils were assayed by in situ hybridization and immunohistochemistry in tissues obtained from monkeys after injection of lipopolysaccharide (LPS) (n = 3) and after injection of saline as a control (n = 2). Coagulation parameters were measured before and at 1.5 and 3 hours after injections.

RESULTS

In LPS-treated monkeys, TF mRNA and protein were induced not only in monocytes and endothelial cells, but also in neutrophils accumulating in the liver 3 hours after LPS injection. Thrombin-antithrombin III complex and fibrin degradation products D-dimer levels were significantly increased at 3 and 1.5 hours after LPS injection compared with controls.

CONCLUSIONS

Neutrophils are a source of TF and are implicated in direct activation of the coagulation cascade in the early phases of sepsis in the monkey. These results give important information for the treatment of sepsis.

Suppression of human monocyte tissue factor synthesis by antisense oligodeoxynucleotide

Tissue factor (TF) is a cellular receptor and cofactor for factor V11/V11a which initiates the blood coagulation cascade. An understanding of TF cell biology is therefore of critical importance to the pathophysiology of many disorders. We have utilized an antisense oligodeoxynucleotide (aODN), directed against human blood monocyte TF mRNA, to investigate the feasibility of inhibiting the synthesis of TF. CD14 receptor-mediated endocytosis was used as a means of delivering TF aODN to monocytes. This DNA carrier system consists of the fab portion of anti-CD14 antibody covalently linked to poly (L-lysine). Co-treatment of monocytes with TF aODN and endotoxin resulted in 80.4 +/- 2.2% suppression of TF activity when compared with control endotoxin stimulated cells. Control experiments with TF sense ODN, mismatched aODN, and an irrelevant aODN were performed to exclude nonspecific inhibitory effects. The cytotoxicity of the DNA carrier complex was also evaluated. These results demonstrate that this TF mRNA antisense ODN specifically suppressed the synthesis of biologically active monocyte TF and that antisense ODNs might therefore represent a useful tool in the investigation of monocyte/macrophage TF function.