Serological assessment of wound healing in Crohn's disease

Background Poor wound healing may be a feature in the pathophysiology of Crohn′s Disease (CD) and may lead to fibrosis and intestinal obstruction and possibly fistula formation. During wound healing, platelets are activated and recruited at the wound site, where the fibrin-rich clot is formed and strengthened when fibrin-stabilising factor 13 transglutaminase (FXIII) generates fibrin-fibrin cross-links. Once hemostasis has been achieved, insoluble cross-linked fibrin is dissolved into D-dimer, a small fibrinolysis-specific degradation product that can be cleared by the liver. We examined the quality of wound healing in patients with CD by measuring newly developed blood-based biomarkers that quantify fibrin remodelling and D-dimer, a direct measurement of FXIII-crosslink fibrin. Methods A monoclonal antibody recognising the plasmin cleavage site of fibrinogen β-chain was developed and applied in both a competitive ELISA (D-fragment) and a sandwich ELISA (D-dimer). D-fragment assay quantify total clot resolution by measuring both fibrinogen and fibrin degradation products. The D-dimer assay quantify FXIII cross-linked fibrin by measuring the D-dimer. The fibrin formation marker, fibrinopeptide A (FPA), was determined by a competitive ELISA kit. Serum from 35 CD patients and 15 non-IBD classified patients (age above 25) was included in the study together with 39 age-matched healthy subjects. Results CD patients had a significantly higher level of FPA (p < 0.0001, AUC: 0.92, Figure A) and D-fragment/D-dimer ratio (p < 0.0001, AUC: 0.85, Figure D), and a significantly lower level of D-dimer (p < 0.001, AUC: 0.78, Figure C) compared with healthy subjects. Non-IBD patients had a significantly higher level of FPA (p < 0.0001, AUC: 0.94, Figure A) and D-fragment/D-dimer ratio (p < 0.05, AUC: 0.75, Figure D) compared with healthy subjects. None of the biomarkers had enough diagnostic power to differentiate CD patients from non-IBD patients.