2014 Volume 57 Issue 5 Pages 442-451
Purpose: Plasmin, a serine protease, is involved in degradation of the extracellular matrix either directly, or indirectly through activation of metalloproteases and other zymogens. Plasmin plays an important role in several physiological and pathological phenomena such as fibrinolysis, inflammation, and tissue remodeling. Recently, plasmin has been demonstrated to activate cell signaling, suggesting that it may also participate in the inflammatory response. In this study, we demonstrated that plasmin participates in cyclooxygenase-2 (COX-2) expression and prostaglandin E2 (PGE2) secretion in cultured human dental pulp cells through calcineurin activation.
Methods: Human dental pulp cells were cultured in 10% fetal calf serum (FCS) -supplemented alpha-minimal essential medium (α-MEM). When the cells were confluent, they were incubated in α-MEM containing 1% FCS for 24 h, and then stimulated with 100 nmol/l plasmin. The expression of COX-2 mRNA was determined by reverse transcription-polymerase chain reaction (RT-PCR). COX-2 protein expression and nuclear translocation of NFAT were detected by Western blotting, and the PGE2 concentration in the culture medium was measured using an enzyme immunoassay kit.
Results: When the cells were stimulated by plasmin, PGE2 release was clearly increased in a time-dependent manner. COX-2 mRNA and protein expression, and NFATc1 nuclear translocation were markedly enhanced by plasmin. However, in the presence of the calcineurin antagonist FK506, these effects were suppressed. Stimulation of the cells with the PAR-1 agonist SFLLRN yielded similar results as observed with plasmin treatment.
Conclusion: Plasmin is involved in COX-2 production and PGE2 secretion via calcineurin activation, suggesting that it is involved in inflammation in the human dental pulp.
