Neutrophil Activation Promotes Fibrinogen Oxidation and Thrombus Formation in Behçet Disease

Blood samples were collected from 98 consecutive BD patients attending our dedicated Center and from 70 age- and sex-matched healthy controls; in all patients fibrinogen function and structure, fibrin susceptibility to plasmin-lysis, plasma redox status, leukocyte oxidative stress markers, and possible reactive oxygen species sources were examined. Thrombin-catalyzed fibrin formation and fibrin susceptibility to plasmin-induced lysis were significantly impaired in BD patients (P<0.001). These findings were associated with increased plasma oxidative stress markers (P<0.001) and with a marked carbonylation of fibrinogen (P<0.001), whose secondary structure appeared deeply modified. Neutrophils displayed an enhanced NADPH oxidase activity and increased reactive oxygen species production (P<0.001), which significantly correlated with fibrinogen carbonylation level (r(2)=0.33, P<0.0001), residual β-band intensity (r(2)=0.07, P<0.01), and fibrinogen clotting ability (r(2)=0.073, P<0.01) CONCLUSIONS: In BD patients, altered fibrinogen structure and impaired fibrinogen function are associated with neutrophil activation and enhanced reactive oxygen species production whose primary source is represented by neutrophil NADPH oxidase.