Factor XIII improves platelet adhesion to fibrinogen by protein disulfide isomerase-mediated activity

Abstract

Background: Factor XIII (FXIII), a plasma pro-transglutaminase, consists of two A subunits and two B subunits (FXIIIA2B2). Following activation by thrombin, it cross-links fibrin chains at the final step of coagulation. We previously reported that FXIII subunit A (FXIIIA) serves as a protein disulfide isomerase (PDI), and that PDI promotes platelet adhesion and aggregation. Objective: This study sought to examine possible mechanistic effect of FXIII on platelet adhesion to fibrinogen; specifically, the role of its PDI activity. Methods: Ex vivo experiments: Blood platelets derived from five patients with hereditary FXIIIA deficiency before and after treatment with Fibrogammin-P (FXIIIA2B2 concentrate) were washed and incubated on immobilized fibrinogen. Bound platelets were stained and counted by microscopy. In vitro experiments: Platelets derived from patients before treatment and five healthy controls were washed and analyzed for adhesion in the presence or absence of Fibrogammin-P or recombinant FXIII (FXIIIA2 concentrate). Results: In ex vivo experiments, one hour after Fibrogammin-P treatment, mean (±SEM) platelet adhesion to fibrinogen increased by 27±2.32% (pb 0.001). In in vitro experiments, treatment with Fibrogammin-P or recombinant FXIII (10 IU/mL each) enhanced platelet adhesion to fibrinogen (in patients, by 29.95±6.7% and 29.05±5.3%, respectively; in controls, by 26.06±3.24% and 26.91±4.72, respectively; pb 0.04 for all). Iodoacetamide-treated FXIII (I-FXIII), where transglutaminase activity is blocked, showed similar enhanced adhesion as untreated FXIII. By contrast, addition of an antibody that specifically blocks FXIIIA-PDI activity inhibited FXIII-mediated platelet adhesion to fibrinogen by 65%. Conclusion: These findings indicate that FXIII-induced enhancement of platelet adhesion is mediated by FXIII-PDI activity.© 2012 Elsevier Ltd. All rights reserved. IntroductionCoagulation factor XIII (FXIII) is a plasma pro-transglutaminase. Following activation by thrombin, it cross-links fibrin chains at the final step of coagulation to form a soluble clot [1]. FXIII circulates in plasma as a heterotetramer of two A subunits (FXIIIA2 -the active transglutaminase) and two B subunits (FXIIIB2 -the carrier protein) [1]. Besides its role in hemostasis, FXIII accelerates wound healing [2], probably by its pro-angiogenic effects [3] as well as by stimulation of monocytes and fibroblasts [4]. Several new lines of evidence point to the involvement of FXIII in platelet function as well [5][6][7][8]. FXIII subunit A (FXIIIA) was detected on thrombin-receptor-activated platelets [5], and platelets were found to adhere to FXIII-covered surface [6]; this interaction depended on the intact fibrinogen binding to integrin αIIbβ3 [5,6]. Accordingly, no clot retraction was noted in FXIIIA knock-out mice [7], and patients with FXIII deficiency, a rare hereditary life-long bleeding disorder [8], showed reduced fibrinogen binding to thrombin-stimulated platelets and reduced platelet adhesion to fibrinogen-covered surface ...

Coagulation factor XIII is a critical driver of liver regeneration after partial hepatectomy

“…Although multiple mechanisms alter platelet function in the context of liver regeneration [39], FXIII-induced cross-linking stabilizes fibrin [40], and this may be critical to drive platelet accumulation in the early moments after PHx. Moreover, multiple studies have shown that FXIII directly contributes to platelet adhesion to fibrin and drives platelet responses secondary to fibrin(ogen)-integrin α IIb β 3 engagement [41][42][43]. In addition to platelets, fibrin engagement of leukocyte β2 integrins [44] could contribute to liver regeneration by modulating effector functions of either neutrophils or macrophages, both cell types linked to liver regeneration in mice and humans [45,46].…”

The intersection of protein disulfide isomerase and cancer associated thrombosis

“…Cell surface receptors can be activated via binding, but also through cleavage by proteases; kallekrein-14 and cathepsin G are PDI substrates and are known to cleave and activate members of the PAR receptor family (8, 39, 40). PDI can modulate phosphatidylserine (PS) exposure (16, 41) and may regulate coagulation through disulfide regulation of tissue factor, activation of factor XI, maturation of platelet factor V, and attenuating factor XIII cross-linking activity toward fibrin (8, 9, 13, 42, 43). More globally, PDI is believed to sense and regulate the redox state of the extracellular membrane, by interacting with small molecule effectors like glutathione and nitric oxide (NO), and modulating the redox state of other extracellular thiol isomerases (5, 6, 44).…”

“…Interaction with either of these receptors leads to platelet activation which can enhance the metastatic potential of the tumor through shielding from an anti-tumor immune response (59, 60, 62). Several cell surface receptors, receptor agonist proteases, and large scaffolding proteins which bind to these receptors across multiple cells and strengthen the thrombus have all been identified as PDI substrates (9, 12, 14, 33, 35, 38, 43).…”

Thiol Isomerases – A Possible Target for Thrombosis Control

“…Это может быть одной из причин тромбозов при АФС. Также показано, что фактор XIII (FXIII; его А-цепь) обладает активностью ПДИ, и тем самым способствует адгезии и агрегации тромбоцитов [43,44].…”