Impaired Hemostasis and the Role of Oxidative Stress-Induced Signaling in Thrombotic Disorders—Where We Stand Today

Both primary and secondary hemostasis consist of finely regulated pathways, forming a blood clot to stop bleeding. These orchestrated mechanisms involve multiple plasma- and platelet/endothelial-derived receptors, factors, enzymes, and proteins, such as the von Willebrand factor (vWF), fibrinogen, and thrombin. Over-activation or improper resolution of the coagulation cascade leads to severe pathological disorders, arterial and venous. Despite the fact that the genetic etiology of thrombophilia has gained the main research interest, there is growing evidence that the disturbed redox network of key hemostatic pathways signals thrombus formation. Oxidized LDL in dyslipidemias and many endogenous and exogenous compounds act as pro-oxidant stimuli that lead to post-translational modifications of proteins, such as sulfenylation, nitrosation, disulfide formation, glutathionylation, etc. Oxidation of cysteine and methionine residues of vWF, fibrinogen, and thrombomodulin has been detected at thrombotic episodes. Increased homocysteine levels due to, but not restricted to, methylenetetrahydrofolate reductase gene (MTHFR) mutations have been incriminated as a causative factor for oxidative stress, leading to a pro-thrombotic phenotype. Alterations in the vascular architecture, impaired vascular relaxation through decreased bioavailability of NO, accumulation of Nε-homocysteinylated proteins, ER stress, and endothelial cells’ apoptosis are among the pro-oxidant mechanisms of homocysteine. This review article focuses on describing key concepts on the oxidant-based molecular pathways that contribute to thrombotic episodes, with emphasis on the endogenous compound, homocysteine, aiming to promote further molecular, clinical, and pharmacological research in this field.