Exogenous Bradykinin Inhibits Tissue Factor Induction and Deep Vein Thrombosis via Activating the eNOS/Phosphoinositide 3-Kinase/Akt Signaling Pathway

Background/aims: Bradykinin has been shown to exert a variety of protective effects against vascular injury, and to reduce the levels of several factors involved in the coagulation cascade. A key determinant of Thrombin generation is tissue factor (TF). However, whether bradykinin can regulate TF expression remains to be investigated.

Methods: To study the effect of bradykinin on TF expression, we used Lipopolysaccharides (LPS) to induce TF expression in human umbilical vein endothelial cells and monocytes. Transcript levels were determined by RT-PCR, protein abundance by Western blotting. In the in vivo study, bradykinin and equal saline were intraperitoneally injected into mice for three days ahead of inferior cava vein ligation that we took to induce thrombus formation, after which bradykinin and saline were injected for another two days. Eventually, the mice were sacrificed and tissues were harvested for tests.

Results: Exogenous bradykinin markedly inhibited TF expression in mRNA and protein level induced by LPS in a dose-dependent manner. Moreover, the NO Synthase antagonist L-NAME and PI3K Inhibitor LY294002 dramatically abolished the inhibitory effects of bradykinin on tissue factor expression. PI3K/Akt signaling pathway activation induced by bradykinin administration reduced the activity of GSK-3β and MAPK, and reduced NF-x03BA;B level in the nucleus, thereby inhibiting TF expression. Consistent with this, intraperitoneal injection of C57/BL6 mice with bradykinin also inhibited the thrombus formation induced by ligation of inferior vena cava.

Conclusion: Bradykinin suppressed TF protein expression in human umbilical vein endothelial cells and monocytes in vitro; in line with this, it inhibits thrombus formation induced by ligation of inferior vena cava in vivo.