Fibrin stimulates microfilament reorganization and IL-1 beta production inhuman monocytic THP-1 cells

Fibrin plays important roles in the wound healing processes, including bloo d clotting and platelet aggregation. Additional activities of fibrin were f ound in this study, which utilizes human THP-1 cells treated 1,25-(OH)(2) v itamin D-3 and plasminolytic fragments derived from fibrin, Coated fibrin f ragment E on culture plates induced cell adhesions and morphological change s of the THP-1 cells, being resembled to tissue macrophages. Morphological changes of the THP-1 cells were caused by microfilament reorganization. IL- 1 beta production was increased in the THP-1 cells by adherent fibrin fragm ent E, but not by fibrin fragment D or by fibrinogen fragment E, The elevat ion of IL-1 beta production is caused by transcriptional activation. Incuba tion with cytochalacin D, an actin polymerization inhibitor, prevents both microfilament reorganization and morphological changes, but has no effect o n the IL-1 beta production stimulated by fibrin fragment E, This data sugge sts that the IL-1 beta production in the THP-1 cells do not require microfi lament reorganization and integrin aggregation, Taken together, these resul ts indicate that fibrin matrix plays an additional role in the stimulation of monocytes for production of IL-1 beta, morphological changes and cell ad hesion, resulting in the facilitation of the wound healing processes.