Recent evidence implicating
tissue factor and the
protein C pathway in the hypercoagulable state associated with intestinal
inflammation suggests that
thrombin is likely to contribute to this response. The objective of this study was to assess the role of
thrombin in the extraintestinal
thrombosis associated with experimental
colitis.
Thrombus formation was quantified in microvessels of the cremaster muscle in mice with
dextran sodium sulfate (DSS)-induced colonic
inflammation. The light/
dye endothelial injury model was used to elicit
thrombus formation in DSS colitic mice treated with either
hirudin,
heparin, or
antithrombin III. The initiation and propagation/stabilization phases of
thrombus formation were quantified using the time of onset of the
thrombus and time to blood flow cessation, respectively.
Thrombus formation was accelerated in arterioles of DSS colitic mice, as exhibited by significant reductions in the time of
thrombus initiation and propagation/stabilization. Colitic mice treated with
hirudin,
heparin, or
antithrombin III did not exhibit a significant change in the time of onset of the
thrombus compared with untreated colitic mice. However, all three
antithrombin agents largely prevented the DSS-induced reduction in the time to flow cessation following light/
dye injury, with
hirudin offering complete protection. These findings indicate that
thrombin plays a major role in the extraintestinal
thrombus formation associated with experimental
colitis.
Thrombin appears to contribute to the propagation/stabilization, rather than initiation, phase of the
colitis-associated thrombogenesis at the distant vascular site. The results support the
therapeutic use of
antithrombin agents for reducing the risk of
thromboembolism in patients with
inflammatory bowel disease.