Bi-directional communication: coagulation versus inflammation.

Abstract

The process of inflammation that is initiated by tissue injury or infection is connected to the process of coagulation. The highlight of inflammation, a process of migration of inflammatory leukocytes is facilitated by numerous proteases, including matrix metalloproteinase 9 (MMP-9, gelatinase B) degrading extracellular matrix (ECM) and basement membrane components. On the other hand, the process of blood clotting which can be activated by either external or intrinsic pathways inhibits the bleeding process and restores the continuity of blood vessel walls. This sort of damage accompanies also inflammation. The process of blood clotting is directed by the plasminogen system as its components (activators: t-PA, u-PA and inhibitors: t-PAI, u-PAI) regulate activity of plasmin which degrades the clot. The plasminogen system and MMP-9 cooperate in numerous physiological processes, especially in regard to the degradation of ECM. In addition, plasmin is one of the main activators of pro-MMP-9 thus it affects the activity and release of MMP-9. Furthermore, gelatinase B takes part in angiogenesis by facilitating migration of vascular endothelial cells. On the other hand, MMP-9 has the ability to degrade plasminogen leading to generation of angiostatin that inhibits angiogenesis. The article discusses recent data linking the process of coagulation and the plasminogen system to the process of inflammation (mostly via MMP-9) and describes complexity of their interactions.