Role of phospholipases A2 in diabetic retinopathy: in vitro and in vivo studies.
Diabetic retinopathy is one of the leading causes of blindness and the most common complication of diabetes with no cure available. We investigated the role of phospholipases A2 (PLA2) in diabetic retinopathy using an in vitro blood-retinal barrier model (BRB) and an in vivo streptozotocin (STZ)-induced diabetic model. Mono- and co-cultures of endothelial cells (EC) and pericytes (PC), treated with high or fluctuating concentrations of glucose, to mimic the diabetic condition, were used. PLA2 activity, VEGF and PGE2 levels and cell proliferation were measured, with or without PLA2 inhibition. Diabetes was induced in rats by STZ injection and PLA2 activity along with VEGF, TNFα and ICAM-1 levels were measured in retina. High or fluctuating glucose induced BRB breakdown, and increased PLA2 activity, PGE2 and VEGF in EC/PC co-cultures; inhibition of PLA2 in mono- or co-cultures treated with high or fluctuating glucose dampened PGE2 and VEGF production down to the levels of controls. High or fluctuating glucose increased EC number and reduced PC number in co-cultures; these effects were reversed after transfecting EC with small interfering RNA targeted to PLA2. PLA2 and COX-2 protein expressions were significantly increased in microvessels from retina of diabetic rats. Diabetic rats had also high retinal levels of VEGF, ICAM-1 and TNFα that were reduced by treatment with a cPLA2 inhibitor. In conclusion, the present findings indicate that PLA2 upregulation represents an early step in glucose-induced alteration of BRB, possibly upstream of VEGF; thus, PLA2 may be an interesting target in managing diabetic retinopathy.
Department of Clinical and Molecular Biomedicine, Section of Pharmacology and Biochemistry, School of Medicine, University of Catania, Catania, Italy.
Gabriella
G
Lupo
Carla
C
Motta
Giovanni
G
Giurdanella
Carmelina Daniela
CD
Anfuso
Mario
M
Alberghina
Filippo
F
Drago
Salvatore
S
Salomone
Claudio
C
Bucolo
D000818:Animals; D001813:Blood-Retinal Barrier / Q000201:enzymology* / Q000276:immunology / Q000473:pathology; D002417:Cattle; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D018920:Coculture Techniques; D003921:Diabetes Mellitus, Experimental / Q000150:complications / Q000201:enzymology* / Q000276:immunology / Q000473:pathology; D003930:Diabetic Retinopathy / Q000201:enzymology* / Q000209:etiology / Q000276:immunology / Q000473:pathology; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D005947:Glucose / Q000494:pharmacology; D008297:Male; D018613:Microscopy, Confocal; D020286:Pericytes / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D064801:Phospholipase A2 Inhibitors / Q000494:pharmacology; D054467:Phospholipases A2 / Q000096:biosynthesis / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013311:Streptozocin / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
D064801:Phospholipase A2 Inhibitors; D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat; D013311:Streptozocin; D054467:Phospholipases A2; D005947:Glucose
Diabetes; Endothelial/pericytes co-culture, Cytokines; Phospholipases A(2); Retina