title: Expression of lysophosphatidic acid, autotaxin and acylglycerol kinase as biomarkers in diabetic retinopathy.
abstract: The proinflammatory lysophosphatidic acid (LPA) is a potent activator of several transcriptional factors and signaling pathways and a potent modulator of genes involved in inflammation, angiogenesis and fibrosis. This study was conducted to measure the levels of LPA and LPA-producing enzymes, autotaxin (ATX) and acylglycerol kinase (AGK) in the vitreous fluid from patients with proliferative diabetic retinopathy (PDR) and to correlate their levels with clinical disease activity and the level of vascular endothelial growth factor (VEGF). In addition, we examined the expression of ATX, AGK and VEGF receptor-2 (VEGFR-2) in the retinas of diabetic rats. Vitreous samples from 42 PDR and 35 nondiabetic patients were studied by enzyme-linked immunosorbent assay. Vitreous samples and retinas of rats were examined by Western blot analysis. VEGF, LPA and AGK levels in vitreous samples from PDR patients were significantly higher than those in control patients without diabetes (p < 0.001 for all comparisons). ATX levels in PDR with active neovascularization and inactive PDR were significantly lower than those in nondiabetic patients (p = 0.045). Mean VEGF and AGK levels in PDR with active neovascularization were significantly higher than those in inactive PDR and nondiabetic patients (p < 0.001 for both comparisons). A significant correlation was observed between levels of VEGF and levels of AGK in PDR patients (r = 0.954; p < 0.001). Western blot analysis revealed a significant increase in the expression of AGK and VEGFR-2 in vitreous samples and the retinas of diabetic rats compared to nondiabetic controls, whereas ATX was significantly downregulated. Our findings suggest that ATX-AGK-LPA signaling axis might be an important player in the development and progression of diabetic retinopathy.
authors.affiliation: Department of Ophthalmology, College of Medicine, King Saud University, Riyadh, Saudi Arabia. abuasrar@KSU.edu.sa
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Abu El-Asrar
authors.forename: Ghulam
authors.initials: G
authors.lastname: Mohammad
authors.forename: Mohd Imtiaz
authors.initials: MI
authors.lastname: Nawaz
authors.forename: Mohammed Miraj
authors.initials: MM
authors.lastname: Siddiquei
authors.forename: Dustan
authors.initials: D
authors.lastname: Kangave
authors.forename: Ghislain
authors.initials: G
authors.lastname: Opdenakker
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D003930:Diabetic Retinopathy / Q000378:metabolism*; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D008246:Lysophospholipids / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism; D014822:Vitreous Body / Q000378:metabolism; D055815:Young Adult; D000099189:Lysophospholipase D
chemical_list: D015415:Biomarkers; D008246:Lysophospholipids; D010727:Phosphoric Diester Hydrolases; D017853:Phosphotransferases (Alcohol Group Acceptor); D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2; D000099189:Lysophospholipase D; C467484:VEGFA protein, human; C492429:AGK protein, human; C025944:acylglycerol kinase; C032881:lysophosphatidic acid