AIM: To investigate the role of endoplasmic reticulum stress(ERS)in oxidized low-density lipoprotein(OxLDL)induced retinal pigment epithelium(RPE)cells apoptosis.

METHODS: The human RPE cell line ARPE19 was cultured in low glucose DMEM medium with 10% fetal bovine serum. Experiments were divided into three groups: control group(normal cultured ARPE19), OxLDL group(with 5, 10, 25, 50, 100μg/mL of OxLDL), and LDL group(with 5, 10, 25, 50, 100μg/mL of OxLDL)and cultured 24h. The CCK8 kit(Cell Counting Kit-8)was used to detect cell activity, the flow cytometry was used to detect the percentage of apoptosis and the Western blotting was used to detect the expression of ERS-related proteins and apoptosis-related enzymes. The confocal microscope was used to observe the phagocytosis of Dil-labeled OxLDL(Dil-OxLDL)in RPE cells.

RESULTS: The results of CCK8 showed that when compared with control group, with cell viability of(100±5.637)%, different concentrations(5, 10, 25, 50, 100 μg/mL)of OxLDL could change cell viability significantly(F=41.20, P<0.05), and cell viability of each group was(105.298±9.395)%、(97.106±5.417)%、(77.015±4.055)%、(67.613±3.853)% and(43.872±9.532)%; However, the same concentrations(5, 10, 25, 50, 100 μg/mL)of LDL treatment had no influence on cell viability(P>0.05), and the cell viability changes were(97.55±6.217)%,(99.640±3.586)%,(90.495±2.786)%,(83.552±9.171)% and(90.910±1.429)% respectively. Flow cytometry results showed that OxLDL with concentrations higher than 25μg/mL could induce apoptosis apparently. The apoptosis rates of the blank group, the OxLDL(25μg/mL)group, and the LDL(25μg/mL)group were(5.271±0.519)%,(41.23±1.686)% and(13.07±2.579)% respectively, and the differences among them were statistically significant(F=329.8, P<0.01); The Western blotting results showed that the expression levels of ERS-related proteins and apoptosis-related enzymes in the OxLDL(25μg/mL)group were significantly higher than those in the control group and the LDL group(Caspase-12:F=50.53, P<0.05; GRP78:F=55.60, P<0.05; CHOP:F=38.22, P<0.05; XBP-1:F=53.94, P<0.05; ATF6:F=20.01, P<0.05), while there was no difference between the control group and the LDL group(P>0.05).

CONCLUSION: ERS is involved in the apoptosis of RPE cells induced by OxLDL, and regulating ERS may achieve the purpose of inhibiting RPE cell apoptosis and thus treating RPE apoptosis-related diseases.