Plasminogen and Its Receptors as Regulators of Cardiovascular Inflammatory Responses

In addition to its role in fibrinolysis, plasminogen (Plg) influences inflammatory cell migration and thereby plays a prominent role in cardiovascular pathology. The contribution of Plg to inflammatory cell recruitment depends on its tethering to the surface of responding cells. Plasminogen receptors (Plg-Rs) are heterogeneous and can be classified as tailless, lacking cytoplasmic tails, or tailed (having cytoplasmic tails). In vivo observations implicate several tailless Plg-Rs in inflammatory responses. Tailed Plg-Rs on leukocytes include several integrins, which have also been implicated in Plg-dependent responses. Surface expression of both tailless and tailed Plg-Rs can be modulated in number and/or function. A common mechanism involving intracellular calcium mobilization and calcium channels regulates expression of both classes of Plg-Rs. Data are emerging to indicate that targeting Plg and Plg-Rs may limit inflammation and cardiovascular pathology.