title: Increased N-terminal cleavage of alpha-2-antiplasmin in patients with liver cirrhosis.
abstract: BACKGROUND
  The activity of alpha-2-antiplasmin (α2AP), the main fibrinolytic inhibitor, is modified by N- and C-terminal proteolytic cleavages. C-terminal cleavage converts plasminogen-binding α2AP (PB-α2AP) into a non-plasminogen-binding derivative. N-terminal cleavage by antiplasmin-cleaving enzyme (APCE), a soluble, circulating derivative of fibroblast activation protein (FAP), turns native Met-α2AP into Asn-α2AP, which is more quickly crosslinked into fibrin.
  
  
  OBJECTIVE
  We developed two novel enzyme-linked immunosorbent assays (ELISAs) to determine the N-terminal variation of α2AP to test the hypothesis that liver cirrhosis, characterized by increased expression of FAP/APCE, results in increased N-terminal cleavage of α2AP.
  
  
  METHODS
  α2AP and FAP/APCE antigen levels were measured in the plasma samples of 75 patients with cirrhosis with different severities and 30 healthy control individuals. The percentage of N-terminal cleavage of α2AP was calculated.
  
  
  RESULTS
  Compared with levels (median [interquartile range]) in control individuals, total PB-α2AP levels and Met-PB-α2AP levels were reduced in cirrhosis patients (27.3 [21.4-41.3] μg mL(-1) vs. 56.2 [49.6-62.8] μg mL(-1) , P < 0.001, and 2.7 [1.7-5.5] μg mL(-1) vs. 12.1 [11.0-15.3] μg mL(-1) , P < 0.001, respectively). Interestingly, the percentage of N-terminal cleavage was increased in the patients (87.8 [85.0-91.6]% vs. 77.2 [72.2-79.8]% in controls, P < 0.001), as well as the plasma FAP/APCE levels (166 [60-550] ng mL(-1) in patients vs. 107 [67-157] ng mL(-1) in controls, P < 0.001). Additionally, all variables significantly correlated with the severity of disease.
  
  
  CONCLUSIONS
  Using our novel ELISAs we found increased N-terminal cleavage of α2AP in liver cirrhosis patients, which correlated with the severity of disease and is likely to have reflected the increased FAP/APCE levels in these patients.
authors.affiliation: Department of Hematology, Erasmus University Medical Center, Rotterdam, the Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Uitte de Willige
authors.forename: J J M C
authors.initials: JJ
authors.lastname: Malfliet
authors.forename: H L A
authors.initials: HL
authors.lastname: Janssen
authors.forename: F W G
authors.initials: FW
authors.lastname: Leebeek
authors.forename: D C
authors.initials: DC
authors.lastname: Rijken
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000941:Antigens / Q000737:chemistry; D016022:Case-Control Studies; D010450:Endopeptidases; D005260:Female; D005342:Fibrinolysis; D005355:Fibrosis / Q000378:metabolism; D018093:Gelatinases / Q000737:chemistry; D005838:Genotype; D006801:Humans; D008103:Liver Cirrhosis / Q000097:blood*; D008297:Male; D008565:Membrane Proteins / Q000737:chemistry; D008875:Middle Aged; D010958:Plasminogen / Q000737:chemistry; D020641:Polymorphism, Single Nucleotide; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D012697:Serine Endopeptidases / Q000737:chemistry; D012995:Solubility; D055815:Young Adult; D000979:alpha-2-Antiplasmin / Q000737:chemistry*; D000099167:Fibroblast Activation Protein Alpha
chemical_list: D000941:Antigens; D010450:Endopeptidases; D018093:Gelatinases; D008565:Membrane Proteins; D010958:Plasminogen; D011994:Recombinant Proteins; D012697:Serine Endopeptidases; D000979:alpha-2-Antiplasmin; D000099167:Fibroblast Activation Protein Alpha
keywords: alpha-2-antiplasmin; case-control study; fibrinolysis; fibrosis; liver cirrhosis