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Factor concentrates for the treatment of factor XIII deficiency.

Factor XIII deficiency is a severe autosomal recessive bleeding disorder associated with a characteristic pattern of neonatal hemorrhage and a lifelong bleeding diathesis. Even relatively minor trauma can be followed by prolonged and recurrent bleeding. Intracranial hemorrhage is a frequent complication. With the development of safe and effective factor XIII concentrates, reliable prophylactic treatment is possible. Two plasma-derived, virus-inactivated factor XIII concentrates are currently in production. The first, Fibrogammin P, (Centeon LLC, King of Prussia, PA, USA; and Centeon Pharma GmbH, Marburg, Germany) is marketed in Europe, South America, South Africa, and Japan. It is distributed in the United States under a Food and Drug Administration Investigational New Drug Application. A second factor XIII concentrate (Bio Products Laboratory, Elstree, UK) is available for use only on a "named patient" compassionate basis in the United Kingdom. Patients with factor XIII deficiency who receive appropriately timed periodic infusions of such factor XIII concentrates are able to live normal lives, free from catastrophic bleeding episodes.

Factor XIII↗

Two novel and one recurrent missense mutation in the factor XIII A gene in two Dutch patients with factor XIII deficiency.

Congenital factor XIII (FXIII) deficiency is a rare autosomal recessive disorder, usually attributed to a defect in the FXIII A subunit, whose genetic basis has been studied in a number of cases. We describe here the genetic variations found in two unrelated patients with FXIII deficiency. Both patients, under prophylactic substitution with FXIII concentrate, showed low plasma FXIII A subunit antigen levels with undetectable A subunit antigen in the platelets and normal plasma B antigen levels, which indicate that the defects are present in the A subunit of the molecule. Both probands were heterozygous for a previously reported G-->A transversion in exon 8 of the FXIII A subunit gene (Arg326Gln substitution). Proband 1 was also heterozygous for a novel G-->T transversion in exon 7, which predicts a Val316Phe substitution. Two of her sons were heterozygous for this mutation and showed low FXIII activity and FXIII A subunit antigen levels. Val316 is a well-conserved amino acid among the transglutaminase family, located within the core domain, close to the Cys314 member of the catalytic triad. Proband 2 had a unique 2-bp (TT) insertion in one of the alleles within or adjacent to the -7 to -20 T tail of intron A. This insertion was not found in 50 healthy individuals, which supports this being the second mutation in this patient.

Adult↗

Analysis of factor XIII substrate specificity using recombinant human factor XIII and tissue transglutaminase chimeras.

Human factor XIII (FXIII) and tissue transglutaminase (tTG) are homologous proteins. FXIII requires thrombin for activation and cross-links the gamma chains of fibrin(ogen) more efficiently than the Aalpha chains. On the other hand, tTG is thrombin-independent and forms predominantly Aalpha and Aalpha-gamma chain complexes. Previous work from this laboratory demonstrated that amino acid residues within exon 7 of FXIII were important for catalysis (Hettasch, J. M., and Greenberg, C. S. (1994) J. Biol. Chem. 269, 28309-28313). To determine to what extent the primary amino acid sequence within exon 7 defines substrate specificity, exon 7 of FXIII was replaced with the corresponding exon of tTG using gene splicing by overlap extension. Other work from this laboratory (Achyuthan, K. E., Slaughter, T. F., Santiago, M. A., Enghild, J. J., and Greenberg, C. S. (1993) J. Biol. Chem. 268, 21284-21292) using synthetic peptides identified two other domains that might play a role in substrate recognition (located in exons 3 and 5). Therefore, recombinant chimeras of FXIII/tTG were also created in which these two exons were exchanged. FXIII, tTG, and chimeras 3, 5, and 7 were expressed in Escherichia coli, purified, and the nature of the fibrin cross-linking pattern of these five proteins was determined by immunoblot analysis. FXIII preferentially formed the gamma-gamma dimer, whereas tTG formed Aalpha-gamma complexes. Chimera 7 formed Aalpha-gamma complexes that resembled the cross-linking pattern of tTG. This finding demonstrates that the primary amino acid sequence of exon 7 of tTG confers some of the specificity for the Aalpha and Aalpha-gamma cross-link pattern characteristic of tTG. Chimera 5 exhibited reduced cross-linking activity (50% of FXIII activity) but still retained preference for formation of the gamma-gamma dimer, whereas chimera 3 was not active. In conclusion, exchanging the primary amino acid sequence of the active site exon of human FXIII with that of human tTG modifies the enzyme such that the fibrin cross-linking pattern more closely resembles that of tTG (Aalpha and Aalpha-gamma complexes) instead of FXIII (gamma-gamma dimers).

Amino Acid Sequence↗

Structural features associated with the binding of glutamine-containing peptides to Factor XIII.

Activated Factor XIII a2 catalyzes the formation of intermolecular gamma-glutamyl- epsilon -lysyl cross-links in the fibrin network. Solution NMR studies were carried out to characterize, the structural features associated with the binding of glutamine-containing peptides to Factor XIII. A coupled uv/vis kinetic assay demonstrated that K9 peptide (1-10), alpha2-antiplasmin (1-15), and alpha2-antiplasmin (1-15 Q4N) all function as glutamine-containing substrates for activated Factor XIII a2. 2D TOCSY spectra of the peptides exhibit upfield chemical shifts for the glutamine protons in the presence of Factor XIII. These results indicate that the reactive peptide glutamines are encountering a distinctive environment within the Factor XIII active site. 1D proton line-broadening and 2D transferred-NOESY studies reveal that the glutamines and residues located C-terminally come in direct contact with the enzyme and adopt an extended conformation. Substrates with sequences similar to alpha2-antiplasmin (1-15) are proposed to bind both at the catalytic site and at a neighboring apolar region.

Amino Acid Sequence↗

Non-proteolytic activation of cellular protransglutaminase (placenta macrophage factor XIII).

Plasma Factor XIII is a zymogen (plasma protransglutaminase) with the tetrametric structure A2B2, whereas the cellular protransglutaminase, i.e. Factor XIII in the platelet and monocyte/macrophage, consists exclusively of A subunits (A2). It is generally accepted that at Ca2+ concentrations comparable with that in plasma the proteolytic removal of an N-terminal activation peptide is the prerequisite for the Ca2(+)-induced formation of a catalytically active configuration of subunit A. In this study it was demonstrated that at high concentrations NaCl or KCl induced a non-proteolytic activation of cellular (placental macrophage) but not plasma protransglutaminase. The activation depended on time and salt concentration, and Ca2+, in the range 0-20 mM, greatly enhanced the activation process. At 1.25 M-NaCl maximal activation occurred within 60 min in the presence of 2 mM-CaCl2, and even at physiological NaCl concentration a slow progressive activation could be observed in the presence of Ca2+. The specific activity of salt-activated Factor XIII was 1.5-2.0-fold higher than that obtained after thrombin activation. The non-proteolytic activation of cellular protransglutaminase was abolished by the addition of subunit B of plasma Factor XIII in stoichiometric amount, which suggests that (one of) the physiological function(s) of the B subunit in plasma Factor XIII is to prevent the slow spontaneous activation of A subunit that would occur in a plasmatic environment.

Calcium↗

Factor XIII deficiency. A family study by measurement of factor XIII subunits A and S.

A girl with congenital factor XIII deficiency and her large family have been studied by electroimmunoassay of factor XIII subunits A and S. The homozygote has absence of subunit A and a decreased level of subunit S. The heterozygotes have decreased levels of both subunits, and were more readily identified by measurement of subunit A than by the ratio subunit S/subunit A. The mother of the propositus appears to be a new heterozygote, but heterozygosity on the paternal side is traced through three generations.

Adult↗

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.

Adolescent↗

Clinical pharmacokinetics of a placenta-derived factor XIII concentrate in type I and type II factor XIII deficiency.

Limited data are available about the pharmacokinetics of placenta-derived factor XIII (FXIII) concentrate in patients with FXIII deficiency. This concentrate contains only the active subunit A but not the carrier subunit B of the factor, and perplexities have been raised about its clinical use. Moreover, no data are available on its use in the rare patients completely lacking both subunit A and subunit B. Therefore, we evaluated the pharmacokinetics of a commercial placenta concentrate in three patients with FXIII deficiency: two lacking subunit A (type II) and one lacking both subunits (type I). The elimination half-life of the infused placenta subunit A in the three patients was very similar (280, 283, and 272 hr) and was also consistent with the previously reported data for plasma-derived FXIII. No thrombin-independent activity was observed in our concentrate batches. The recovery was significantly lower in the type I patient, in whom infusion of subunit A was not able to elicit a monthly increment of subunit B, as usually observed in type II patients. Monthly infusions of placenta concentrate (at higher dosage in type I patient) have been administered to our patients for two to three years and no evidence of inhibitor against factor XIII activity has been observed. We conclude that placenta concentrates may be as effective as plasma derivatives in replacement therapy of factor XIII deficiency, even in patients who lack subunit B.

Adult↗

[Factor XIII deficiency in adults with acute leukemia: results of a substitution therapy with factor XIII (author's transl)].

A decrease in fibrin stabilizing factor (Factor XIII) is the most frequent coagulation disorder seen in adults with acute leukemia. Patients with prominent reduction of factor XIII (FSF) (less than 50%) were substituted with a factor XIII concentrate from human placenta, and factor XIII plasma concentration and bleeding tendency were followed up during the course of the disease. After substitution plasma, factor XIII activity went up to normal levels in most of the patients. As compared to the course of 12 patients with distinct factor XIII reduction without factor XIII therapy, there were less bleeding complications in 13 courses of patients with prominent reduction of factor XIII substituted with factor XIII concentrate and in 11 with normal or only slightly reduced factor XIII levels.

Acute Disease↗

Electron microscopy and hydrodynamic properties of factor XIII subunits.

Factor XIII is a transglutaminase important in blood coagulation and fibrinolysis. Its function is to catalyze peptide bond formation between the gamma-carboxamide group of glutamines in one protein and the epsilon-amino group of lysine in another. There are two zymogenic forms of factor XIII: one is a noncovalent, intracellular dimer (A2); the other is a noncovalent, extracellular tetramer (A2B2). The catalytic function resides in the activated A chain (A2.). Purified forms of factor XIII (A2B2, A2, A2.B2, B) were prepared and analyzed by electron microscopy, gel filtration, and gradient centrifugation. Hydrodynamic constants were derived. Electron microscopy of rotary-shadowed molecules showed A2 to consist of two globular particles each about 6 x 9 nm in size. The A2 dimer is significantly elongated, 18 nm long and 6 nm in diameter. Sedimentation and gel filtration of the A2 dimer are consistent with this asymmetric structure. B protein is a filamentous, flexible strand with kinks, with a contour length of 30 nm and a diameter of approximately 2-3 nm. The sedimentation and gel filtration behavior of the B subunit are characteristic of a highly asymmetric molecule. The observed structure of the B subunit, combined with data for its amino acid sequence, suggests a modular structure. The B subunit is a member of a family of proteins composed of tandem, repeating structures (referred to as GP-I domains); the structure seen by electron microscopy for B subunit is probably applicable to all proteins in this family. Plasma and platelet factor XIII zymogens are tetrameric and dimeric, but B protein, in the absence of A protein, appears to be monomeric. Our model for the A2B2 zymogen has the elongated A2 dimer forming the core and the two B strands wrapping around the outside.

Centrifugation, Density Gradient↗

Unusual presentation of factor XIII deficiency.

Factor XIII deficiency is a rare inherited bleeding disorder that is often difficult to diagnose. The standard screening tests are normal in these patients and their bleeding phenotype may be variable. We report the case of a 3-year-old girl who presented with an intracranial haemorrhage. Several confounding factors, such as the suspicion of an arteriovenous malformation and the development of a deep venous thrombosis, led to a delay in the diagnosis of factor XIII deficiency. Subsequently, her brother was also found to have severe factor XIII deficiency. This case highlights the importance of a detailed history and of screening families in which index cases have been identified. It should also remind physicians that bleeding disorders may have unusual presentations and should be sought when investigating unexplained bleeding.

Consanguinity↗

The factor XIII V34L polymorphism accelerates thrombin activation of factor XIII and affects cross-linked fibrin structure.

Factor XIII on activation by thrombin cross-links fibrin. A common polymorphism Val to Leu at position 34 in the FXIII A subunit is under investigation as a risk determinant of thrombosis. Because Val34Leu is close to the thrombin cleavage site, the hypothesis that it would alter the function of FXIII was tested. Analysis of FXIII subunit proteolysis by thrombin using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and high-performance liquid chromatography showed that FXIII 34Leu was cleaved by thrombin more rapidly and by lower doses than 34Val. Mass spectrometry of isolated activation peptides confirmed the predicted single methyl group difference and demonstrated that the thrombin cleavage site is unaltered by Val34Leu. Kinetic analysis of activation peptide release demonstrated that the catalytic efficiency (k(cat)/K(m)) of thrombin was 0.5 for FXIII 34Leu and 0.2 (micromol/L)(-1) x sec(-1) for 34Val. Presence of fibrin increased the catalytic efficiency to 4.8 and 2.2 (micromol/L)(-1) x sec(-1), respectively. Although the 34Leu peptide was released at a similar rate as fibrinopeptide A, the 34Val peptide was released more slowly than fibrinopeptide A but more quickly than fibrinopeptide B generation. Cross-linking of gamma- and alpha-chains appeared earlier when fibrin was incubated with FXIII 34Leu than with 34Val. Fully activated 34Leu and 34Val FXIII showed similar cross-linking activity. Analysis of fibrin clots prepared using plasma from FXIII 34Leu subjects by turbidity and permeability measurements showed reduced fiber mass/length ratio and porosity compared to 34Val. The structural differences were confirmed by electron microscopy. These results demonstrate that Val34Leu accelerates activation of FXIII by thrombin and consequently affects the structure of the cross-linked fibrin clot.

Blood Coagulation↗

Seven novel mutations in the factor XIII A-subunit gene causing hereditary factor XIII deficiency in 10 unrelated families.

BACKGROUND: Hereditary factor (F)XIII deficiency is a rare bleeding disorder mostly due to mutations in FXIII A subunit. OBJECTIVES: We studied the molecular basis of FXIII deficiency in patients from 10 unrelated families originating from Israel, India and Tunisia. METHODS: Exons 2-15 of genomic DNA consisting of coding regions and intron/exon boundaries were amplified and sequenced. Structural analysis of the mutations was undertaken by computer modeling. RESULTS: Seven novel mutations were identified in the FXIIIA gene. The propositus from the Ethiopian-Jewish family was found to be a compound heterozygote for two novel mutations: a 10-bp deletion in exon 12 at nucleotides 1652-1661 (followed by 22 altered amino acids and termination codon) and Ala318Val mutation. The propositus of the Tunisian family was homozygous for C insertion after nucleotide 863 within a stretch of six cytosines of exon 7. This insertion results in generation of eight altered amino acids followed by a termination codon downstream. The propositus from Indian-Jewish origin was found to be homozygous for G to T substitution at IVS 11 [+1] resulting in skipping of exons 10 and 11. In addition to the Ala318Val mutation, three of the novel mutations identified are missense mutations: Arg260Leu, Thr398Asn and Gly210Arg each occurring in a homozygous state in an Israeli-Arab and two Indian families, respectively. CONCLUSIONS: Structure-function correlation analysis by computer modeling of the new missense mutations predicted that Gly210Arg will cause protein misfolding, Ala318Val and Thr398Asn will interfere with the catalytic process or protein stability, and Arg260Leu will impair dimerization.

Catalysis↗

Thrombin hydrolysis of V29F and V34L mutants of factor XIII (28-41) reveals roles of the P(9) and P(4) positions in factor XIII activation.

In blood coagulation, thrombin helps to activate factor XIII by cleaving the activation peptide at the R37-G38 peptide bond. The more easily activated factor XIII V34L has been correlated with protection from myocardial infarction. V34L and V29F factor XIII mutant peptides were designed to further characterize substrate binding to thrombin. HPLC kinetic studies have been carried out on thrombin hydrolysis of FXIII activation peptide (28-41), FXIII (28-41) V34L, FXIII (28-41) V29F, and FXIII (28-41) V29F V34L. The V34L mutations lead to improvements in both K(m) and k(cat) whereas the V29F mutation primarily affects K(m). Interactions of the peptides with thrombin have been monitored by 1D proton line broadening NMR and 2D transferred NOESY studies. The results were compared with previously published X-ray crystal structures of thrombin-bound fibrinogen Aalpha (7-16), thrombin receptor PAR1 (38-60), and factor XIII (28-37). In solution, the (34)VVPR(37) and (34)LVPR(37) segments of the factor XIII activation peptide serve as the major anchor points onto thrombin. The N-terminal segments are proposed to interact transiently with the enzyme surface. Long-range NOEs from FXIII V29 or F29 toward (34)V/LVPR(37) have not been observed by NMR studies. Overall, the kinetic and NMR results suggest that the factor XIII activation peptide binds to thrombin in a manner more similar to the thrombin receptor PAR1 than to fibrinogen Aalpha. The V29 and V34 positions affect, in different ways, the ability of thrombin to effectively hydrolyze the activation peptide. Mutations at these sites may prove useful in controlling factor XIII activation.

Amino Acid Sequence↗

Genotype/phenotype correlations for coagulation factor XIII: specific normal polymorphisms are associated with high or low factor XIII specific activity.

Factor XIII is a transglutaminase essential for normal hemostasis. We have studied the plasma FXIII levels and FXIII activity in 71 individuals and found these to be normally distributed. FXIII specific activity is also normally distributed. However, we show that FXIII activity is not directly dependent on FXIII levels, and individuals with low FXIII levels may have high FXIII activity and vice versa. We have determined the FXIIIA genotype in these individuals to assess whether the variation observed in FXIII specific activity is dependent on specific polymorphisms in the FXIIIA gene. Our data show that the Leu34 and Leu564 variants give rise to increased FXIII specific activity, while the Phe204 variant results in lower FXIII specific activity. We also report preliminary evidence that the Phe204 polymorphism may be associated with recurrent miscarriage. Overall, we have identified 23 unique FXIIIA genotypes. Certain specific FXIIIA genotypes consistently give rise to high, low, or median FXIII specific activity levels, while others appear to have little or no consistent influence on the FXIII phenotype. These genotype to phenotype relationships are discussed in light of the growing interest in the role of FXIII in clinical problems involving an increased thrombotic tendency.

Abortion, Habitual↗

Lack of clinical efficacy of additional factor XIII treatment in patients with steroid refractory colitis. The Factor XIII Study Group.

Patients with active ulcerative colitis have decreased levels of factor XIII (FXIII) activity, which is important for woundhealing. Recent uncontrolled studies claimed a beneficial effect of Factor XIII on clinical symptoms of ulcerative colitis, in particular intestinal bleeding. The objective of this trial was to evaluate the benefits of additional FXIII treatment in steroid-refractory patients with ulcerative colitis in a prospective, double blind, placebo-controlled study. A total of 28 patients were enrolled between October 1994 and January 1997. Primary objective of this study was the time until cessation of visible intestinal bleeding with 14 days after the start of treatment. Patients were treated for ten days either by i.v. application of FXIII concentrate or by placebo. The analysis of the primary efficacy criterion, cessation of intestinal bleeding, by a planned interim analysis showed no significant differences between the treatment groups (p = 0.8). This resulted in the termination of the study. The same applied to the CAI score. No patient in both treatment groups reached remission according to the colo-/-sigmoidoscopy score. Due to the high number of patients (16 of 28) who had to be excluded from the per-protocol analysis (e.g. changes to the concomitant medication) only the intention-to-treat population was analyzed. Overall the study showed no beneficial effect of additional FXIII treatment on active steroid-refractory ulcerative colitis. These results do not confirm previous open label studies which had reported a significant improvement of clinical symptoms.

Adolescent↗