The Apoptotic Effects Of PM_2.5 On Human Umbilical Vein Endothelial Cells And Its Mechanism

Object: In this study, the apoptotic effect and potential mechanism of ambient fine particle matter(PM2.5) on human umbilical vein endothelial cells(HUVECs) were explored to provide scientific data for assessing its impacts on human cardiovascular disease and for the related department of government to make reasonable decisions.Methods: The treated concentration of PM2.5 were 0.2, 1, 5, 25 μg/m L and the PPS buffer was used as the negative control. The proliferation of HUVEC treated with PM2.5 was determined by the MTT method. The HUVECs stained with Hoechst 33258 were observed with fluorescence microscope for the apoptotic bodies. After V-FITC-PI double staining, the flow cytometry was employed to determine the rate of apoptosis cells. The proteins and their phosphorylation related in the apoptosis pathways were determined by Western blot.Results: The proliferation of HUVECs decreased with the increasing PM2.5 concentrations and presented a clear negative dose-effect relationship and time-effect relationship, compared with the negative group(P < 0.05, P < 0.01). The classic apoptotic bodies were observed in HUVECs treated with PM2.5 under the fluorescence microscope. The apoptotic rate of HUVECs in treated groups were increased with the increasing concentration of PM2.5 and presented a clear positive dose-effect relationship, compared with the negative control group(P < 0.05, P < 0.01). The total protein levels of p53 and p38 and their phosphorylation(phospho-53 [Ser15] and Phospho-p38 MAPK) increased with the increasing levels of PM2.5. The rate of Bax/Bcl-2 was increased due to the increased Bax protein and decreased Bcl-2 in the PM2.5 treated groups compared with the negative control group. The total protein levels of caspase 9, caspase 3, caspase 7 and PARP decreased with the increasing cleaved caspase 9, caspase 3, caspase 7 and PARP in the HUVECs.Conclusion: The PM2.5 can induce the apoptotic effect to HUVECs and there were a clear dose-effect relationship. The molecular mechanism is that PM2.5 may trigger the apoptotic signaling pathways of caspase 9, 3,7 and PARP in HUVECs through increasing the total protein level of p53 and p38 and their phosphorylation.