Variations in prostate-specific antigen free/total ratio in acute stress

Pharmacological Inhibition of Serine Proteases to Reduce Cardiac Inflammation and Fibrosis in Atrial Fibrillation

Systemic inflammation correlates with an increased risk of atrial fibrillation (AF) and thrombogenesis. Systemic inflammation alters vessel permeability, allowing inflammatory and immune cell migration toward target organs, including the heart. Among inflammatory cells infiltrating the atria, macrophages and mast cell have recently attracted the interest of basic researchers due to the pathogenic mechanisms triggered by their activation. This chemotactic invasion is likely implicated in short- and long-term changes in cardiac cell-to-cell communication and in triggering fibrous tissue accumulation in the atrial myocardium and electrophysiological re-arrangements of atrial cardiomyocytes, thus favoring the onset and progression of AF. Serine proteases are a large and heterogeneous class of proteases involved in several processes that are important for cardiac function and are involved in cardiac diseases, such as (i) coagulation, (ii) fibrinolysis, (iii) extracellular matrix degradation, (iv) activation of receptors (i.e., protease-activated receptors [PPARs]), and (v) modulation of the activity of endogenous signals. The recognition of serine proteases substrates and their involvement in inflammatory/profibrotic mechanisms allowed the identification of novel cardio-protective mechanisms for commonly used drugs that inhibit serine proteases. The aim of this review is to summarize knowledge on the role of inflammation and fibrosis as determinants of AF. Moreover, we will recapitulate current findings on the role of serine proteases in the pathogenesis of AF and the possible beneficial effects of drugs inhibiting serine proteases in reducing the risk of AF through decrease of cardiac inflammation and fibrosis. These drugs include thrombin and factor Xa inhibitors (used as oral anticoagulants), dipeptidyl-peptidase 4 (DPP4) inhibitors, used for type-2 diabetes, as well as novel experimental inhibitors of mast cell chymases.

Prostate-specific antigen kallikrein and the heart

Currently, there is growing interest regarding prostate-specific antigen (PSA) and the cardiovascular system. Increased PSA serum levels have been reported after prolonged cardiopulmonary resuscitation, cardiac surgery, extracorporeal cardiopulmonary bypass, acute myocardial infarction (AMI) and coronary artery stenting. The possible role of PSA in cardiac events has been questioned due to the finding of PSA decrease during AMI and by the correlation of variation in PSA levels with coronary lesions and occurrence of major adverse cardiac events. Complexed PSA forms and uncomplexed PSA forms are observed in the bloodstream but the increasing formation of irreversible bound PSA seems to be a crucial finding during AMI. Large studies need to be carried out to confirm these preliminary results and to elucidate unclear aspects. These findings present many potential directions for future research including the role of uncomplexed forms of PSA, the possible distribution of PSA in the heart, the relative expression levels in heart disease states, the mode of expression regulation and other potential specific substrates. The journey of PSA investigation could be longer than initially expected.

Prostate-specific antigen kallikrein complexes and acute myocardial infarction

Recently, attention has focused on prostate-specific antigen kallikrein and the cardiovascular system. The finding of diminished PSA during acute myocardial infarction and the correlation of variation of PSA with coronary lesions and occurrence of major adverse cardiac events have opened a possible new intriguing scenario. As with many stories in biology, the tale of PSA can be more complex than was first appreciated. In the bloodstream, the proteolytic activity of PSA is inhibited by the formation of irreversible complexes with serum protease inhibitors and other acute-phase proteins. We noticed that the formation of irreversible PSA complexes (reflected by the increased bound PSA) has significant correlation with high-sensitivity C-reactive protein (hsCRP) and that seems to play a crucial role in the adverse event prevention.