Effects of a snake venom metalloproteinase, triflamp, on platelet aggregation, platelet-neutrophil and neutrophil-neutrophil interactions:: involvement of platelet GPIbα and neutrophil PSGL-I

The biologically active components from Viperidae venoms specifically affect cell-matrix interactions, and have been utilized for developing anti-adhesive therapy as anti-thrombotic and antiangiogenic agents. Utilizing platelet aggregometry coupled with flow cytometry, we found that a metalloproteinase isolated from Trimeresurus flavoviridis, termed triflamp, inhibited heterotypic adhesion between platelets and neutrophils in whole blood samples. Triflamp is a monomeric glycoprotein with a molecular weight of similar to28 kDa. Triflamp has a N-terminal amino acid sequence homologous to other venom metalloproteinases isolated from T flavoviridis. The enzymatic activity of triflamp was inhibited by EDTA and phenanthroline but not by PMSF. Moreover, triflamp is a pure alpha-fibrinogenase. Studies aimed at determining the nature of triflamp in affecting platelets or neutrophils revealed a selective inhibitory activity to glycoprotein (GP) lbalpha-dependent platelet aggregation and PSGL-1-dependent neutrophil homotypic aggregation, indicating that its effects are rather specific. As judged by Western blotting, GPlbalpha on. platelets and PSGL-1 on neutrophils are the substrates of triflamp. In conclusion, we suggest the novel role of venom metalloproteinase from Viperidae affecting the blood cell-cell interactions, thus offering a potential approach for further exploration of anti-inflammatory agents.