[High expression of P-selectin (CD62P) after platelet activation in vitro inhibits bacterial proliferation and induces apoptosis-like changes].

Objective To compare the expression level of P-selectin (CD62P) on platelets surface under the stimulation of Staphylococcus aureus (SA) and Escherichia coli (E.coli), explore the inhibitory effects of platelets on the their proliferation, and further investigate the molecular mechanism by which platelets inhibit the proliferation of bacteria. Methods 10 CFU/mL SA and E.coli were co-cultured with 2×10/L purified platelets, and the A values of the two groups were detected; The CD62P of platelets was detected by flow cytometry after platelets co-cultured with SA and E.coli for 2 hours and 4 hours. The platelet factor 4 (PF4) released by platelets was detected by ELISA; After co-cultured with SA and E.coli for 12 hours, the proliferation, phosphatidylserine (PS) eversion and cell membrane potential of SA and E.coli were analyzed by flow cytometry. Results After platelets co-cultured with SA and E.coli for 6 hours, the turbidity of SA decreased significantly and the turbidity of E.coli showed a slight decrease. Compared with the control group, the counts of bacterial plates decreased after two kinds of bacteria co-cultured with platelets. After co-cultured with SA and E.coli for 2 hours and 4 hours, the CD62P levels of platelets increased. In particular, the CD62P level of platelets co-cultured with SA was significantly higher than that of platelets co-cultured with E.coli. The release of intracellular protein PF4 of platelet increased significantly after bacteria stimulation. The proliferation rate of SA and E.coli decreased after co-cultured with platelets, and SA and E.coli exhibited PS eversion and depolarization of cell membrane potential. Conclusion High expression of CD62P inhibits the proliferation and induces apoptotic changes of SA and E.coli after platelets activation in vitro, and the inhibitory effect of platelets on SA was better than that of E.coli.