Glucose-mediated regulation of transforming growth factor-beta (TGF-beta) and TGF-beta receptors in human retinal endothelial cells.
OBJECTIVE
Diabetic retinopathy is a micro-angiopathy affecting predominantly small vessels of the retina. Clinical trials have demonstrated a strong association between tight glucose control and a reduction in the incidence and the severity of diabetic retinopathy. Transforming growth factor beta (TGF-beta) is involved in the control of endothelial cell proliferation, adhesion, and deposition of extracellular matrix, thus TGF-beta may play a role in the control of endothelial cell proliferation seen in the disease. We wished to investigate the regulation of transforming growth factor beta and its receptors (type I and II) in human retinal endothelial cells exposed to a range of glucose concentrations.


METHODS
Human retinal endothelial cells were isolated from donor eyes, cultured in vitro and exposed to a range of glucose concentrations (0-25 mmol/l). TGF-beta protein and mRNA levels were determined by ELISA and Northern analysis, respectively. The binding affinities and TGF-beta receptor numbers were defined using a binding assay.


RESULTS
Northern hybridisation and ELISA showed that after 8 hours, the level of TGF-beta mRNA and protein was significantly higher at 15mmol/l compared to 5, 20 or 25mmol/ l. Binding assays showed that for high glucose (25 mmol/l), human retinal endothelial cells express a population of TGF-beta receptors with higher affinity for its ligand than at 5 or 15 mmol/l.


CONCLUSIONS
These results demonstrate that glucose regulates TGF-beta mRNA and protein production and also TGF-beta receptor expression in human retinal endothelial cells. Thus, the glucose-mediated changes that occur in diabetic patients may expose human retinal endothelial cells to potential angiogenic factors which may influence disease progression.
Medical School Department of Ophthalmology Schotland Aberdeen,
M M
MM
Pascal
J V
JV
Forrester
R M
RM
Knott
D001667:Binding, Competitive / Q000187:drug effects; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D012333:RNA, Messenger / Q000378:metabolism; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism*; D012171:Retinal Vessels / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000096:biosynthesis* / Q000235:genetics
D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D005947:Glucose