Role of the polyol pathway in high glucose-induced apoptosis of retinal pericytes and proliferation of endothelial cells.
OBJECTIVE
The selective degeneration of pericytes and the proliferation of endothelial cells (ECs) appear to be associated with microaneurysm formation, an initial deficit in the early stage of diabetic retinopathy. The preventive effect of aldose reductase (AR) inhibitor (ARI) for high glucose-induced pericyte loss and EC growth was investigated.


METHODS
The effect of high glucose (30 mM) exposure in the presence or absence of ARI for the cell growth of porcine pericytes and ECs was examined with the use of an in vitro coculture system to mimic the interaction between pericytes and ECs. To determine the role of transforming growth factor (TGF)-beta, its amount in culture media was measured, and the effects of the treatment of TGF-beta or neutralizing antibody on EC growth were examined.


RESULTS
Abundant expression of AR and increased levels of polyol and apoptosis induced by high glucose were observed in pericytes, but not in ECs. ECs overexpressing AR cultured in high-glucose medium showed decreased cell viability. The growth-inhibitory effect of ECs on coculture with pericytes was attenuated by exposure to a high glucose concentration. Biochemical assays disclosed that the levels of active TGF-beta in media were linked to EC growth. Supply of active TGF-beta to coculture medium containing 30 mM D-glucose restored the inhibitory activity on EC growth.


CONCLUSIONS
ARI rescued pericytes from high glucose-induced apoptosis and maintained the levels of TGF-beta, resulting in the prevention of cocultured EC growth.
Takamura
Yoshihiro
Y
Department of Ophthalmology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
Tomomatsu
Takeshi
T
Kubo
Eri
E
Tsuzuki
Syousai
S
Akagi
Yoshio
Y
D000449:Aldehyde Reductase / Q000378:metabolism; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D017209:Apoptosis; D002196:Capillaries / Q000166:cytology; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D018920:Coculture Techniques; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D042783:Endothelial Cells / Q000166:cytology* / Q000201:enzymology / Q000502:physiology; D005947:Glucose / Q000008:administration & dosage* / Q000494:pharmacology; D020286:Pericytes / Q000502:physiology*; D011108:Polymers / Q000378:metabolism*; D012171:Retinal Vessels / Q000166:cytology* / Q000187:drug effects; D013552:Swine; D016212:Transforming Growth Factor beta / Q000276:immunology / Q000378:metabolism
D000906:Antibodies; D011108:Polymers; D016212:Transforming Growth Factor beta; C024617:polyol; D000449:Aldehyde Reductase; D005947:Glucose