Vascular endothelial growth factor C promotes survival of retinal vascular endothelial cells via vascular endothelial growth factor receptor-2.
OBJECTIVE
To determine vascular endothelial growth factor C (VEGF-C) expression in retinal endothelial cells, its antiapoptotic potential and its putative role in diabetic retinopathy.


METHODS
Cultured retinal endothelial cells and pericytes were exposed to tumour necrosis factor (TNF)alpha and VEGF-C expression determined by reverse transcriptase-polymerase chain reaction. Secreted VEGF-C protein levels in conditioned media from endothelial cells were examined by western blotting analysis. The ability of VEGF-C to prevent apoptosis induced by TNFalpha or hyperglycaemia in endothelial cells was assessed by flow cytometry. The expression of VEGF-C in diabetic retinopathy was studied by immunohistochemistry of retinal tissue.


RESULTS
VEGF-C was expressed by both vascular endothelial cells and pericytes. TNFalpha up regulated both VEGF-C and vascular endothelial growth factor receptor-2 (VEGFR)-2 expression in endothelial cells in a dose-dependent manner, but had no effect on VEGFR-3. Flow cytometry results showed that VEGF-C prevented endothelial cell apoptosis induced by TNFalpha and hyperglycaemia and that the antiapoptotic effect was mainly via VEGFR-2. In pericytes, the expression of VEGF-C mRNA remained stable on exogenous TNFalpha treatment. VEGF-C immunostaining was increased in retinal vessels in specimens with diabetes compared with retinal specimens from controls without diabetes.


CONCLUSIONS
In retinal endothelial cells, TNFalpha stimulates the expression of VEGF-C, which in turn protects endothelial cells from apoptosis induced by TNFalpha or hyperglycaemia via VEGFR-2 and thus helps sustain retinal neovascularisation.
Zhao
Bojun
B
Cell and Molecular Biology Unit, School of Optometry and Vision Sciences, Cardiff University, UK.
Smith
Gill
G
Cai
Jun
J
Ma
Aihua
A
Boulton
Mike
M
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002417:Cattle; D002470:Cell Survival; D002478:Cells, Cultured; D003930:Diabetic Retinopathy / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D020286:Pericytes / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D012171:Retinal Vessels / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D042582:Vascular Endothelial Growth Factor C / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000502:physiology*
D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D042582:Vascular Endothelial Growth Factor C; D040301:Vascular Endothelial Growth Factor Receptor-2