[Protective effects of autophagy against oxidized LDL-induced injury in endothelial cells].

Objective: To investigate the role of autophagy in oxidized low density lipoprotein (ox-LDL) induced injury of human umbilical vein endothelial cells (HUVEC).

Methods: The cultured HUVECs were randomly divided into four groups of control, ox-LDL, ox-LDL + rapamycin and ox + 3-methyladenine (3-MA). The cells were used to detect the ratio of LC3-II/LC3-I by Western blot while the proliferation and apoptosis of cells measured by MTT and flow cytometry. The lactate dehydrogenase (LDH) activity and endothelin-1 (ET-1) content in the supernatant were detected with enzyme linked immunosorbent assay.

Results: The Ox-LDL treatment up-regulated the ratio of LC3-II/LC3-I in HUVEC (P < 0.01). It increased the activity of LDH (P < 0.01)and content of ET-1 (P < 0.05) in the supernatant. Also it induced the proliferation (P = 0.028) and apoptosis (P < 0.05) of cells. The autophagic inducer rapamycin increased the up-regulation of autophagic level induced by ox-LDL, decreased the activity of LDH and content of ET-1 (P < 0.05) and inhibited the ox-LDL-induced proliferation of cells. Conversely, the autophagic inhibitor 3-MA decreased the elevation of LC3-II/LC3-I induced by ox-LDL (P < 0.01) and increased the cell apoptosis and death.

Conclusion: Ox-LDL exposure can increase the secretion of LDH and ET-1 and induce the proliferation and apoptosis of cells so as to cause a harmful effect in the survival of HUVEC. The injury may be reduced by rapamycin, an autophagic inducer, and elevated by the autophagic inhibitor 3-MA.