Chronic liver injury drives non-traditional intrahepatic fibrin(ogen) crosslinking via tissue transglutaminase.

Essentials Fibrin clots are often implicated in the progression of liver fibrosis. Liver fibrosis was induced in transgenic mice with defects in clot formation or stabilization. Liver fibrosis and fibrin(ogen) deposition do not require fibrin polymerization or factor XIIIa. Fibrin(ogen) is an in vivo substrate of tissue transglutaminase in experimental liver fibrosis. SUMMARY: Background Intravascular fibrin clots and extravascular fibrin deposits are often implicated in the progression of liver fibrosis. However, evidence supporting a pathological role of fibrin in hepatic fibrosis is indirect and based largely on studies using anticoagulant drugs that inhibit activation of the coagulation protease thrombin, which has other downstream targets that promote fibrosis. Therefore, the goal of this study was to determine the precise role of fibrin deposits in experimental hepatic fibrosis. Methods Liver fibrosis was induced in mice expressing mutant fibrinogen insensitive to thrombin-mediated proteolysis (i.e. locked in the monomeric form), termed FibAEK mice, and factor XIII A2 subunit-deficient (FXIII-/- ) mice. Female wild-type mice, FXIII-/- mice and homozygous FibAEK mice were challenged with carbon tetrachloride (CCl4 ) twice weekly for 4 weeks or 6 weeks (1 mL kg-1 , intraperitoneal). Results Hepatic injury and fibrosis induced by CCl4 challenge were unaffected by FXIII deficiency or inhibition of thrombin-catalyzed fibrin polymer formation (in FibAEK mice). Surprisingly, hepatic deposition of crosslinked fibrin(ogen) was not reduced in CCl4 -challenged FXIII-/- mice or FibAEK mice as compared with wild-type mice. Rather, deposition of crosslinked hepatic fibrin(ogen) following CCl4 challenge was dramatically reduced in tissue transglutaminase-2 (TGM2)-deficient (TGM2-/- ) mice. However, the reduction in crosslinked fibrin(ogen) in TGM2-/- mice did not affect CCl4 -induced liver fibrosis. Conclusions These results indicate that neither traditional fibrin clots, formed by the thrombin-activated FXIII pathway nor atypical TGM2-crosslinked fibrin(ogen) contribute to experimental CCl4 -induced liver fibrosis. Collectively, the results indicate that liver fibrosis occurs independently of intrahepatic fibrin(ogen) deposition.

[Is the use of factor XIII for delayed wound healing in patients with head-neck tumors of value?]. / Ist der Einsatz von Faktor XIII bei Wundheilungsstörungen von Patienten mit Kopf-Hals-Tumoren sinnvoll?

BACKGROUND: Factor XIII is known to play an important role in wound healing. In patients with head and neck carcinomas there is an accumulation of risk factors for factor XIII deficiency such as chronic liver disease, extensive tissue lesions, and high intraoperative blood loss. METHOD: Serum levels of factor XIII in 22 patients who had undergone tumor surgery for head and neck carcinoma were measured preoperatively and daily up to 1 week following surgery. Factor XIII was measured with the Berichrome assay as part of our routine laboratory studies. The results were correlated with preoperative pseudocholinesterase (PChe). Factor XIII was substituted for 3 days in 8 patients with persistent wound healing problems that did not improve after two weeks of conservative treatment. RESULTS: We found that PChe levels are a predictor for the development of factor XIII levels during this period. In patients (n = 14) with normal PChe, factor XIII levels reached 86% of the preoperative values 1 week after operation (group 1). In patients (n = 8) with low PChe, the levels reached only 65% (group 2). The rate of wound healing problems was higher in group 2 (6/8) than in group 1 (2/14). In 6 patients treated with factor XIII, the wounds healed within 3 to 7 days. In two cases revision operation was necessary. CONCLUSION: We conclude that the therapy with factor XIII may be successful in patients with wound healing problems. Further studies will be necessary to find out whether prophylactic substitution of factor XIII in patients with low preoperative pseudocholinesterase levels is useful.

A new assay for transglutaminase.

A new solid-phase micro assay for transglutaminase has been developed. Casein bound to microtitre plates and biotin-labelled casein were used as substrates in a transglutaminase-dependent cross-linking reaction. The resulting immobilized biotin was visualized by addition of avidin-labelled alkaline phosphatase followed by p-nitrophenyl phosphate. The colour development was monitored at 405 nm. Tissue transglutaminase was used as test enzyme. The method was also applied to normal and Factor XIII-deficient plasma.

Clinical experience with a pasteurised human plasma concentrate in factor XIII deficiency.

A three-day-old infant presented with umbilical haemorrhage. Factor XIII deficiency was diagnosed. When one month old she commenced prophylactic injections of pasteurised factor XIII concentrate of human plasma origin. During two and a half years treatment there were no haemorrhagic episodes and factor XIII concentrate was well tolerated. Satisfactory post infusion factor XIII levels were achieved. Three transient elevations of aspartate transaminase occurred, the cause of which has not been established. There was no evidence of transmission of hepatitis or H.I.V. infection. A brother, born one year later, is also affected and commenced prophylactic therapy with the same factor XIII concentrate. Experience in these two infants suggests the product is efficacious.

A specific, fluorescent activity staining procedure applied to plasma and red blood cells in congenital factor XIII deficiency.

The activity staining procedure introduced by Stenberg & Stenflo (1979) has been applied to studies on human blood transamidases (transglutaminases; endo-gamma-glutamine:epsilon-lysine transferases; e.g. factor XIII). The technique combines agarose gel electrophoresis with activity staining based on the transamidase catalysed incorporation of monodansylthiacadaverine (N-(5-amino-3-thiapentyl)-5-dimethylamino-1-naphtalenesulfonamide) into casein. The method permits detection of plasma factor XIII activity down to 1% of the normal adult standard. The technique was used on plasma from two patients with tentative congenital plasma factor XIII deficiency (based on clot solubility). No activity was found in platelet poor as well as in platelet rich plasma which confirmed the diagnosis. In the erythrocytes studied in genetic determinations of the plasma and red blood cell transamidases. Using immunoelectrophoresis, the plasma factor XIII b subunit was found to be 43% and 44% of the concentration in normal standard plasma.