title: Impact of homocysteine-thiolactone on plasma fibrin networks.
abstract: Epidemiologic studies have shown that hyperhomocysteinemia is an independent risk factor for vascular disease. Homocysteine (Hcy) circulates as different species, mostly protein bound, and approximately 1% as its reduced form and the cyclic thioester homocysteine-thiolactone (HTL). Despite the level of plasma thiolactone being markedly low, detrimental effects are related to its high reactivity. HTL reacts with proteins by acylation of free basic amino groups; in particular, the epsilon-amino group of lysine residues forms adducts and induces structural and functional changes in plasma proteins. In order to assess the effects of HTL on plasma fibrin networks, a pool of normal plasma incubated with HTL (100, 500 and 1,000 μmol/L, respectively) was evaluated by global coagulation tests and fibrin formation kinetic assays, and the resulting fibrin was observed by scanning electron microscopy. HTL significantly prolonged global coagulation tests in a concentration-dependent manner with respect to control, and increases were up to 14.5%. Fibrin formation kinetic parameters displayed statistically significant differences between HTL-treated plasma and control in a concentration-dependent way, showing higher lag phase and lower maximum reaction velocity and final network optical density. Electron microscopy analysis of HTL plasma networks revealed a compact architecture, with more branches and shorter fibers than control. We can conclude that HTL induced a slower coagulation process, rendering more tightly packed fibrin clots. Since these features of the networks have been related to impaired fibrinolysis, the N-homocysteinylation reactions would be involved in the prothrombotic effects associated to hyperhomocysteinemia.
authors.affiliation: Laboratory of Hemostasis and Thrombosis, Department of Biological Chemistry, School of Exact and Natural Sciences, University of Buenos Aires, Buenos Aires, Argentina.
authors.forename: Valeria
authors.initials: V
authors.lastname: Genoud
authors.forename: Ana María
authors.initials: AM
authors.lastname: Lauricella
authors.forename: Lucía C
authors.initials: LC
authors.lastname: Kordich
authors.forename: Irene
authors.initials: I
authors.lastname: Quintana
mesh_terms: D000818:Animals; D001777:Blood Coagulation / Q000187:drug effects / Q000502:physiology; D002417:Cattle; D005337:Fibrin / Q000737:chemistry / Q000378:metabolism*; D006710:Homocysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D010949:Plasma / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism*
chemical_list: D006710:Homocysteine; D005337:Fibrin; C007957:homocysteine thiolactone