Inhibition of factor XIIIa mediated incorporation of fibronectin into fibrin by pulmonary surfactant

Intra-alveolar deposition of exudated plasma proteins is a hallmark of acut e and chronic inflammatory lung diseases. In particular, fibrin and fibrone ctin may provide a primary matrix for fibrotic lung remodeling in the alveo lar compartment. The present study was undertaken Do explore the effect of two surfactant preparations on the incorporation of fibronectin into fibrin . We observed that surfactant phospholipids are associated with insoluble f ibrin, factor XIIIa-cross-linked fibrin, and cross-linked fibrin with incor porated fibronectin. Factor XIIIa-mediated binding of fibronectin to fibrin was noticeably altered in the presence of surfactant. Coincubation with tw o different commercially available surfactants but not with dipalmitoylphos phatidylcholine alone resulted in a reduction of fibronectin incorporation into fibrin clots by approximately one-third. This effect was not dependent on the calcium concentration. We conclude that 1) factor XIIIa-crosslinked fibrin-fibronectin is able to incorporate surfactant phospholipids in amou nts comparable to fibrin clots without fibronectin and 2) the binding of fi bronectin to fibrin is partially inhibited in the presence of pulmonary sur factant.