Effect of erythropoietin on Caspase-3 expression in light-injured retinal pigment epithelial cells

Yan MENG; Yingjun NIU

ABSTRACT

BACKGROUND:

Recent studies demonstrate that erythropoietin (EPO) can protect retina from light injury, and is the mechanism related to the expression of Caspase-3 in the light-injured retinal pigment epithelium (RPE) cells.

OBJECTIVE:

To study the effects of EPO at different dosages on the expression of Caspase-3 in light-injured human RPE cells.

DESIGN:

Control observation.

SETTING:

Qingdao University Medical College. MATERIALS Adult ARPE-19 cells (American Cell Culture Collection Company); DMEM/F12 mixed medium, fetal bovine serum and trypase (GIBCO Biotechnique Company); recombinant human EPO (rhEPO, Sigma Biotechnique Company); human Caspase-3 quantitative kit (Shanghai Xitang Biotechnique Co.,Ltd); Caspase-3 monoclonal antibody (American Santa Cruz Company); PV6001 immunohistochemistry kit and DAB color reagent kit (Zhongshan Biotechnology Company, Beijing).

METHODS:

The experiment was carried out in the Department of Pathophysiology at Qingdao University Medical College between May 2006 and January 2007. Human RPE-19 cell strain at passages 2-5 were harvested for light injury models, and the passage cells were divided into 7 groups randomly, with 4 apertures in each group①normal control group no light or EPO intervention;②light-injured model group 12-hour illumination, no EPO intervention;③light-injury and EPO groups 12-hour illumination with 10 000, 20 000 and 40 000 U/L EPO;④light-injury and 40 000 U/L EPO and AG490 group 12-hour illumination with 40 000 U/L EPO and inhibitor of Jak2 enzyme 50 000 U/L;⑤light-injury and 40 000 U/L EPO and carbxyl-terminal modulator protein (CTMP) group 12-hour illumination with 40 000 U/L EPO and specific inhibitor of protein kinase B enzyme 100 μmol/L.MAIN OUTCOME

MEASURES:

The enzyme linked immunosorbant assay (ELISA) and immunohistochemistry were used to assess the effects of rhEPO at the different doses on the expression of Caspase-3 in light-injured human RPE cells.

RESULTS:

Caspases-3 was not expressed in RPE cells of the normal control group and was positively expressed in the nucleus of RPE cells of the light-injured model group, showing a specific brown-yellow staining. Expression of Caspase-3 was gradually decreased in every rhEPO group with increase of EPO concentration, with the weakest expression in 40 000 U/L rhEPO group. The effects of EPO on Caspase-3 expression were strongly inhibited in light-injury+ 40 000 U/L EPO +AG490 group and the expression was positive in light-injury +40 000 U/L EPO+CTMP group, which was slightly weaker than light-injured model group.

CONCLUSION:

The rhEPO can reduce the expression of Caspase-3 in the light-injured human RPE cells, and one of the possible mechanisms is the inhibition of light-injured RPE cell apoptosis by the rhEPO.