Tissue factor: a mediator of inflammatory cell recruitment, tissue injury, and thrombus formation in experimental colitis

Abstract

There is growing evidence for an interplay between inflammatory and coagulation pathways in acute and chronic inflammatory diseases. However, it remains unclear whether components of the coagulation pathway, such as tissue factor (TF), contribute to intestinal inflammation, and whether targeting TF will blunt the inflammatory cell recruitment, tissue injury, and enhanced thrombus formation that occur in experimental colitis. Mice were fed 3% dextran sodium sulfate (DSS) to induce colonic inflammation, with some mice receiving a mouse TF-blocking antibody (muTF-Ab). The adhesion of leukocytes and platelets in colonic venules, light/dye-induced thrombus formation in cremaster muscle microvessels, as well as disease activity index, thrombin-antithrombin (TAT) complexes in plasma, and histopathologic changes in the colonic mucosa were monitored in untreated and muTF-Ab-treated colitic mice. In untreated mice, DSS elicited the recruitment of adherent leukocytes and platelets in colonic venules, caused gross and histologic injury, increased plasma TAT complexes, and enhanced thrombus formation in muscle arterioles. muTF-Ab prevented elevation in TAT complexes, reduced blood cell recruitment and tissue injury, and blunted thrombus formation in DSS colitic mice. These findings implicate TF in intestinal inflammation and support an interaction between inflammation and coagulation in experimental colitis.

Figure 1.

Inhibition of TF abrogates the clinical indices of colitis. (A) Changes in DAI on days 0–6 of DSS treatment. Some mice received muTF-Ab on days 0 and 3. (B) Changes in body weight from days 0 to 6 of DSS treatment. Values are reported as means ± SE. *, P < 0.05 versus water; #, P < 0.05 versus DSS.

Figure 2.

TF contributes to the histological damage and inflammation observed in the colon during colitis. Representative images of histology (A–C) and blinded histological scoring of colonic mucosa (D) at day 6 in mice receiving (A) water, (B) DSS, or (C) DSS + muTF-Ab. Values are reported as means ± SE. *, P < 0.05 versus water; #, P < 0.05 versus DSS. Bar, 100 μm.

Figure 3.

Ab blockade of TF virtually abolishes leukocyte and platelet recruitment in postcapillary venules of the colitic colon. Effects of treatment with muTF-Ab on the number of adherent leukocytes (A) and platelets (B) in the colonic microcirculation during DSS colitis. The shaded bar in B denotes the number of platelets bound directly to venular endothelium, whereas the open bar represents platelets binding to adherent leukocytes. Values are reported as means ± SE. *, P < 0.05 versus water; #, P < 0.05 versus DSS.

Figure 4.

DSS and LPS enhance thrombus formation in arterioles and venules, respectively. (A) Time of onset of thrombus formation in cremaster arterioles and venules exposed to light/dye. (B) Time to cessation of flow in the same vessels after light/dye exposure. Values are reported as means ± SE. *, P < 0.05 versus water.

Figure 5.

DSS accelerates the onset of thrombus formation via a TF-dependent mechanism. Time of onset of thrombosis and cessation of flow in arterioles of the cremaster after DSS and pretreatment (during the induction of colitis) or posttreatment (on the day of the experiment before thrombus induction) with muTF-Ab. Values are reported as means ± SE. *, P < 0.05 versus water; #, P < 0.05 versus DSS.

Figure 6.

TF participates in LPS-induced enhancement of thrombotic responses. Time to onset of thrombosis and cessation of flow in venules of the cremaster after LPS and treatment with muTF-Ab. Values are reported as means ± SE. *, P < 0.05 versus water.

Figure 7.

Colitis increases circulating TAT complexes through a pathway that requires TF. TAT levels in plasma samples of DSS colitic mice with or without muTF-Ab treatment. Values are reported as means ± SE. *, P < 0.05 versus water; #, P < 0.05 versus DSS.