[Advanced glycation end products induce apoptosis and expression of apoptotic genes in cultured bovine retinal capillary pericytes].
OBJECTIVE
The purpose of the present study was to examine whether advanced glycation end products (AGE) contribute to the development of apoptosis and expression of apoptotic genes in cultured bovine retinal capillary pericytes (BRPs), in order to investigate retinal microvascular pathologic process during early stage of diabetic retinopathy.


METHODS
After a 4 day incubation with various concentrations of AGE (8, 32, 125, 500, 2,000 mg/L) which were prepared in vitro by incubating bovine serum albumin (BSA) with glucose, we studied the degree of apoptosis and the expressions of apoptotic genes (Bax and bcl-2) in BRPs by staining with the Annexin V-FITC and propidium iodide (PI), terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and immunohistochemistry.


RESULTS
(1) After a 4 day incubation with various concentrations of AGE, BRPs showed typical changes of apoptosis, i.e. shrunken cell size, nuclear condensation associated with DNA fragmentation, a relatively intact cell membrane, and loss of cell viability eventually. (2) AGE could induce significant apoptosis of BRPs in a dose-dependent manner as compared with normal cultures or the albumin group not treated by glucose (r = 0.878, P < 0.01). (3) After a 4 day incubation, the level of pro-apoptotic gene Bax was upregulated (r = 0.855, P < 0.01), whereas the level of pro-survival gene bcl-2 was downregulated by AGE in a dose-dependent manner (r = -0.850, P < 0.01). (4) There was a positive correlation between apoptotic rate and Bax-bcl-2 ratio of BRPs induced by AGE (r = 0.808,P < 0.01).


CONCLUSIONS
AGE can induce a significant apoptosis of BRPs in a dose-dependent manner and the rate of apoptosis was determined by the Bax/bcl-2 ratio. These results suggest that the selective loss of pericytes in diabetic retinopathy involves an apoptotic process.
Chen
Bai-hua
BH
Department of Ophthalmology, the Second Xiangya Hospital of Central South University, Changsha 410011, China. cbhandzxt@163.net
Jiang
De-yong
DY
Tang
Luo-sheng
LS
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics*; D002196:Capillaries / Q000473:pathology; D002417:Cattle; D002478:Cells, Cultured; D003930:Diabetic Retinopathy; D004305:Dose-Response Relationship, Drug; D017127:Glycation End Products, Advanced / Q000008:administration & dosage*; D020286:Pericytes / Q000187:drug effects / Q000473:pathology*; D012160:Retina / Q000473:pathology*
D017127:Glycation End Products, Advanced