Fibrin-stabilizing factor (factor XIII) in the fetus and the newborn infant

Blood coagulation factor XIII and factor XIII deficiency

Factor XIII (FXIII) is a multifunctional pro-γ-transglutaminase that, in addition to its well-known role in hemostasis, has a crucial role in angiogenesis, maintenance of pregnancy, wound healing, bone metabolism, and even cardio protection. FXIII deficiency (FXIIID) is a rare bleeding disorder (RBD) with an estimated incidence of one per two million that is accompanied by life-threatening bleeding such as umbilical cord bleeding, recurrent spontaneous miscarriage, and intracranial hemorrhage (ICH). Today, the disease is successfully managed by FXIII concentrate and recombinant FXIII for prophylaxis, management of minor and major bleeding, treatment of ICH, and successful delivery in women with recurrent pregnancy loss. Molecular analysis of patients with FXIIID revealed a wide spectrum of mutations, most frequently missense mutations in the FXIII-A subunit, with a few recurrent mutations observed worldwide. In vitro expression studies revealed that most of the missense mutations cause intracellular instability of the FXIII protein and, subsequently, FXIIID.

The perioperative course of factor XIII and associated chest tube drainage in newborn and infants undergoing cardiac surgery

BACKGROUND

Perioperative acquired factor XIII deficiency has been looked upon as a potential cause of postoperative bleeding in adult cardiac surgery.

METHODS

Forty-four infants were prospectively studied for the time course of factor XIII in plasma and the effect on chest tube drainage (CTD) and transfusion requirements in the first 24 h after surgery. A reconstituted blood prime (RBP) with fresh-frozen plasma (FFP) and packed red blood cells (PRBC) was used. Samples were taken at baseline, after cardiopulmonary bypass and upon arrival in the ICU. Differences in blood loss and transfusion requirements based on a cutoff value of 70% factor XIII activity at the time of ICU admission were also calculated.

RESULTS

Baseline factor XIII activity was 79%, decreased to 71% after CPB (P = 0.102) and increased back up to 77% at ICU arrival (P = 0.708). There was no significant correlation between factor XIII, CTD, age, cyanosis, platelet count, and transfusion requirements at any time point. Only preoperative fibrinogen levels correlated significantly with factor XIII activity. Perioperative blood transfusions (PRBC P = 0.712, FFP P = 0.909, platelets P = 0.807) and chest tube losses (P = 0.424 at 6 h and P = 0.215 at 24 h) were not significantly different above or below a 70% factor XIII activity at ICU arrival.

CONCLUSION

Factor XIII activity in infants with congenital heart defects is within the lower range of normal adults, independent of patient's age and the presence of cyanosis. Reconstituted blood prime maintains factor XIII activity at sufficient levels during pediatric cardiac surgery. We could not detect a correlation between FXIII and CTD.

Novel aspects of blood coagulation factor XIII. I. Structure, distribution, activation, and function

Blood coagulation factor XIII (FXIII) is a protransglutaminase that becomes activated by the concerted action of thrombin and Ca2+ in the final stage of the clotting cascade. In addition to plasma, FXIII also occurs in platelets, monocytes, and monocyte-derived macrophages. While the plasma factor is a heterotetramer consisting of paired A and B subunits (A2B2), its cellular counterpart lacks the B subunits and is a homodimer of potentially active A subunits (A2). The gene coding for the A and B subunits has been localized to chromosomes 6p24-25 and 1q31-32.1, respectively. The genomic as well as the primary protein structure of both subunits has been established, and most recently the three-dimensional structure of recombinant cellular FXIII has also been revealed. Monocytes/macrophages synthesize their own FXIII, and very likely FXIII in platelets is synthesized by the megakaryocytes. Cells of bone marrow origin seem to be the primary site for the synthesis of subunit A in plasma FXIII, but hepatocytes might also contribute. The B subunit of plasma FXIII is synthesized in the liver. Plasma FXIII circulates in association with its substrate precursor, fibrinogen. Fibrin(ogen) has an important regulatory role in the activation of plasma FXIII. The most important steps of the activation of plasma FXIII are the proteolytic removal of activation peptide by thrombin, the dissociation of subunits A and B, and the exposure of the originally buried active site on the free A subunits. The end result of this process is the formation of an active transglutaminase, which cross-links peptide chains through epsilon(gamma-glutamyl)lysyl isopeptide bonds. Cellular FXIII in platelets becomes activated through a nonproteolytic process. When intracytoplasmic Ca2+ is raised during platelet activation, the zymogen--in the absence of subunit B--assumes an active configuration. The protein substrates of activated FXIII include components of the clotting-fibrinolytic system, adhesive and contractile proteins. The main physiological function of plasma FXIII is to cross-link fibrin and protect it from the fibrinolytic plasmin. The latter effect is achieved mainly by covalently linking alpha 2 antiplasmin, the most potent physiological inhibitor of plasmin, to fibrin. Plasma FXIII seems to be involved in wound healing and tissue repair, and it is essential to maintaining pregnancy. Cellular FXIII, if exposed to the surface of the cells, might support or perhaps take over the hemostatic functions of plasma FXIII; however, its intracellular role has remained mostly unexplored.

Contact with the N termini in the central E domain enhances the reactivities of the distal D domains of fibrin to factor XIIIa

The reaction of Factor XIIIa with fibrin is the last enzyme-catalyzed step on the coagulation cascade, leading to the formation of a normal blood clot. The finding that fibrin is preferred by the cross-linking enzyme about 10-fold over the circulating fibrinogen suggests the operation of a unique substrate-level control for the orderly functioning of the physiological process in the forward direction. An important task is to elucidate the molecular mechanism for the transmission of the signal generated by the thrombin-catalyzed cleavage in the central E domain of fibrin to the distant Factor XIIIa-reactive glutamine residues. By focusing on the substrate sites present in gamma chain remnants of D type domains of fibrinogen and by employing the approach of fragment complementation with the regulatory E domain, which represents the thrombin-modified portion of fibrin, we have now succeeded in reconstructing in solution the phenomenon of kinetic enhancement for the reaction with Factor XIIIa. Two D type preparations (truncated fibrinogen, approximately 250 kDa and D', approximately 105 kDa) were obtained by digestion of human fibrinogen with endo Lys-C. Neither product could be cross-linked by Factor XIIIa, but as shown by the incorporation of dansylcadaverine, both were acceptor substrates for the enzyme. The plasmin-derived D (approximately 105-kDa) product, however, could be cross-linked into DD dimers. In all cases, the admixture of E fragments exerted a remarkable boosting effect on the reactions with Factor XIIIa. Even with native fibrinogen as substrate, cross-linking of gamma chains was enhanced in the presence of E. Nondenaturing electrophoresis was used to demonstrate the complex forming potential of E fragments with fibrinogen, truncated fibrinogen, D', or D. The GPRP tetrapeptide mimic of the GPRV N-terminal sequence of the alpha chains in the E fragments, abolished both complex formation and the kinetic boosting effect of E on the reactions of substrates with Factor XIIIa. Thus, the N-terminal alpha chain sequences seem to act as organizing templates for spatially orienting the D domains, probably during the protofibrillar assembly of the fibrin units, for favorable reaction with Factor XIIIa.

Episodes of increased fibronectin level observed in a patient suffering from recurrent thrombosis related to congenital hypodysfibrinogenaemia (fibrinogen Malmoe)

A study has been conducted in a Swedish patient with severe thrombotic disease and repeated miscarriages related to a hypodysfibrinogenaemia with defective thrombin binding to the abnormal fibrin. The hypodysfibrinogenaemia was found in several members of the family. The patient also had an increased concentration of fibronectin in her plasma at two different occasions. This would appear to be unrelated to the abnormal fibrinogen since a normal concentration of fibronectin has been found in her relatives presenting the same fibrinogen anomaly, and in the patient at two other times. In conclusion, the thrombotic disorder in this patient presenting a congenital hypodysfibrinogenaemia may be explained by the defective thrombin binding to fibrin.

Quantitation of factor XIII by SDS polyacrylamide gel electrophoresis

An electrophoretic method for the determination of f.XIII, based on the capability of f.XIIIa to cross-link fibrin clots (5) was studied, and the great sensitivity of the method confirmed. Thus, with suitable technical conditions, f.XIII activities less than 0.1% of that in normal human plasma could be detected. The results obtained in plasma from various patients and in f.XIII concentrates (cryoprecipitates) corresponded well with those obtained with the dansylcadaverine method (3) and with the urea solubility test, with two exceptions: In a patient with severe congenital f.XIII deficiency, only the present method was sensitive enough to detect any f.XIII-activity (about 0.1%), and in a patient with an inhibitor against f.XIIIa, the dansylcadaverine method failed to detect this. The present method is too laborious for routine screening, but is recommended as an alternative references method. It may prove especially suitable to detect minute amounts of f.XIII.

New colored and fluorescent amine substrates for activated fibrin stabilizing factor (Factor XIIIa) and for transglutaminase

Two fluorescent (FITC and 6-chloro-2-methoxyacridine) and an intensely colored (dabsyl) derivative of cadaverine were synthesized, following earlier work from this laboratory with dansyl-cadaverine, in order to enlarge the scope of possibilities for labeling some gamma-glutamine sites in proteins. Enzyme affinities of the amine substrates for human Factor XIIIa and for guinea pig liver transglutaminase were measured. The utility of dabsylcadaverine was further demonstrated by activity staining of these enzymes, following electrophoresis in agarose, and by measuring the Factor XIII zymogen of human plasma colorimetrically.

Characteristics of the factor VIII protein and Factor XIII in various factor VIII concentrates

The in vitro properties of 5 factor VIII preparations (AHF-Kabi, Hemofil Hyland, AHF-Profilate Abbott, Kryobulin Immuno and Factorate High Purity Armour) and an ordinary cryoprecipitate were studied with reference to factor VIII clotting activity (VIII:C), factor VIII clotting antigen (VIII:CAg), factor VIII related antigen (VIIIR:Ag) (EI, IRMA, CIE), ristocetin cofactor activity (VIIIR:RCF), fibrinogen and factor XIII. All the preparations with the exception of Factorate had higher levels of VIII:CAg than VIII:C indicating inactivation of the biological activity of VIII:C during the procedure. AHF-Kabi (fraction I-0) and the cryoprecipitate, the only preparations capable of normalising the defect in patients with von Willebrand's disease, showed the same level of VIIIR:Ag determined by EI and by IRMA, while all the other preparations (i.e. cryoprecipitates purified further in different ways) had considerably lower levels of VIIIR:Ag determined by IRMA than by EI. Based on these in vitro techniques it seems to be possible to predict which preparations can be used successfully in patients with von Willebrand's disease, while no such conclusions can be made from VIIIR:RCF determinations. EI yielded similar concentrations of factor XIII a subunit in all the preparations tested. 3 functional assays showed high factor XIII activities in AHF-Kabi but low or no activities in the others. Thus, considerable differences were found on the in vitro properties of the proteins in 5 factor VIII concentrates and a cryoprecipitate. The action of proteases and the techniques used in the purification procedure are probably of crucial importance for the properties of the various factors.

Umbilical artery catheterization in newborns. III. Thrombosis--a study of some predisposing factors

Thrombosis following umbilical artery catheterization is a relatively frequent complication. Low fibrinolytic activity in the vessel walls, high factor VIII and low antithrombin III (AT III, Heparin cofactor activity) in blood are factors known to favour the formation of thrombosis. In 30 newborns who died and in 2 foetuses the fibrinolytic activity determined in the aorta and the femoral vessels was in the normal 'adult' range except for a few very immature infants and the foetuses. The five cases with arterial thrombosis were not associated with low fibrinolytic activity. The various factor VIII activities (VIII:C, VIIIR:Ag, and VIIIR:RCF) ant AT III were studied in 30 sick newborns and in 20 healthy newborns. The sick exhibited increased levels of various factor VIII activities (VIIIR:Ag and VIIIR:RCF mainly) and markedly reduced levels of AT III. The high factor VIII activities and the low AT III found will add to the existing risk of thrombosis due to the presence of a foreign material. AT III substitution is suggested as a possible prophylactic.

Factor XIII (fibrin stabilising factor) in Henoch-Schönlein's purpura

In 13 out of 17 consecutive children with Henoch-Schönlein's purpura the factor XIII determined with the dansyl cadaverine method was found to be decreased during the acute phase. The decrease is assumed to be due to a specific degradation by proteolytic enzymes liberated from inflammatory cells, with defective local haemostasis as a result. This assumption is strengthened by the observation that treatment with factor XIII combined with an antifibrinolytic drug controlled life-threatening gastro-intestinal bleeding in one of the patients. It would therefore appear that such treatment might offer a new possibility of controlling severe haemorrhages in Henoch-Schönlein's purpura.

Erosive hemorrhagic gastroduodenitis with fibrinolysis and low factor XIII

Four patients with erosive hemorrhagic gastroduodenitis were found to have high fibrinolytic activity of the gastric juice. No increase in the fibrinolytic activity could be demonstrated in the circulating blood, but the values found for fibrinogen, plasminogen and alpha2-macroglobulin were low. A high content of FDP was found in the serum. All patients had a markedly decreased content of factor XIII. Platelet count and other coagulation components were normal. These findings were interpreted as signs of local fibrinolysis in the diseased parts of the gastrointestinal canal. The bleeding stopped after oral and intravenous administration of a fibrinolytic inhibitor (AMCA Cyclokapron) and of factor XIII-containing concentrate. In bleeding from gastroduodenal ulcer and esophageal varices, no increase in gastric fibrinolytic activity was found. It is suggested that the high local fibrinolytic activity in the stomach in erosive gastritis together with the low content of factor XIII contributes substantially to the hemorrhage in this condition. These observations may lead to a revision of the treatment of such cases.

Generalized proteolysis in a young woman with Weber-Christian disease (nodular nonsuppurative panniculitis)

A patient with Weber-Christian disease (syn. nodular nonsuppurative panniculitis) is reported. The generalized cellular destruction in this patient resulted in liberation of proteolytic enzymes into the circulation, which led to multiple haemostatic disturbances with haemorrhagic diathesis. The most prominent haemostatic defects were thrombocytopenia with a normal life span of isologous platelets, high levels of AHF-related antigen, hypofibronigenaemia with short fibrinogen survival, low levels of Factor XIII (fibrin stabilizing factor = FSF) and increased amounts of fibrin/fibrinogen degradation products (FDP). Proteolytic enzymes, other than thrombin and plasmin which especially degrade Factor XIII and fibrongen, derived from destroyed cells (probably leukocytes) seem to have been involved in the pathogenesis of the bleeding disorder in this patient.

Factor XIII in a clinical material

In 339 patients with various diseases factor XIII (FSF) was determined with the specific amine incorporation method of Lorand et al (1969). Normal values were found in patients with renal (216 patients) or liver diseases (33 patients), in 39 patients with recurrent deep venous thrombosis and in 17 children with congenital cyanotic heart disease. Low levels were found in patients with various conditions, such as sepsis, multiple fractures and combustio complicated by an abnormal proteolytic activity (fibrinolysis and/or activation of the coagulation system with signs of disseminated coagulation). No correlation was found between the FSF and the fibrinogen values or the levels of fibrin/fibrinogen degradation products (FDP). Low FSF values were found in 4 patients with erosive gastritis, with gastrointestinal bleedings and a local fibrinolytic activity in the gastric juice. Although the FSF must be very low (smaller than 1%) if it is to cause bleedings, the low levels in these patients with many other coexisting disturbances in the coagulation system and/or an increased fibrinolytic activity most probably contribute to the increased bleeding tendency in such patients.

The effect of dextran on the lysability of ex vivo thrombi

The lysability was determined of thrombi formed in Chandler tubes before and after infusion of 500 ml dextran 70 to patients undergoing cholecystectomy. 125I-labelled fibrinogen was given the day before operation. Following incubation of the thrombi formed in plasmin, radioactivity remaining in the thrombi and released to the supernatant was determined, as well as fibrinolytic degradation products in the supernatant, using an immunoelectrophoretic method. The dextran infusion was found to increase the radioactivity released from the thrombi to the supernatant from 15.5 plus or minus 7.6% to a maximum of 27.3 plus or minus 8.2% four hours after the infusion (P less than 0.001). A corresponding significant rise of the FDP concentration in the supernatant from 16.8 mug/ml to 44.1 mug/ml was found at the same time. After 24 hours the radioactivity had returned to initial values. The results indicate that dextran infused into patients during surgery increases the lysability of thrombi. It is suggested that this finding at least partly explains the antithrombotic effect of dextran.