ABSTRACT
PURPOSE: Modified (oxidized and/or glycated) low-density lipoproteins (LDLs) have been implicated in retinal pericyte loss, one of the major pathologic features of early-stage diabetic retinopathy. To delineate underlying molecular mechanisms, the present study was designed to explore the global effects of modified LDL on pericyte gene expression. METHODS: Quiescent human retinal pericytes were exposed to native LDL (N-LDL), glycated LDL (G-LDL), and heavily oxidized-glycated LDL (HOG-LDL) for 24 hours, and gene expression was evaluated by DNA microarray analysis. Several of the gene responses were checked, and in each case confirmed by reverse-transcription real-time PCR. RESULTS: HOG-LDL induced a gene expression pattern markedly distinct from that of N-LDL or G-LDL, whereas G-LDL elicited gene expression similar to that of N-LDL. A comparison of responses to HOG-LDL versus N-LDL revealed 60 genes with expression that varied by > or =1.7-fold. The HOG-LDL-responsive genes included members of functional pathways, such as fatty acid, eicosanoid, and cholesterol metabolism; fibrinolytic regulation; cell growth and proliferation; cell stress responses; the kinin system; and angiogenesis. CONCLUSIONS: HOG-LDL elicits gene expression in retinal pericytes that may contribute to pericyte loss and other retinal abnormalities in diabetic retinopathy. Observed proapoptotic and proangiogenic responses to HOG-LDL may be of particular importance in this regard. The genes identified through these studies provide potential therapeutic targets for the prevention and treatment of diabetic retinopathy.
Subject(s)
Gene Expression/drug effects , Lipoproteins, LDL/drug effects , Lipoproteins, LDL/pharmacology , Pericytes/metabolism , Retinal Vessels/cytology , Adult , Capillaries , Gene Expression Profiling , Glycation End Products, Advanced , Humans , Oligonucleotide Array Sequence Analysis , Pericytes/drug effects , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
According to a current paradigm cardiovascular diseases can be initiated by exposure of vascular cells to qualitatively modified low-density lipoproteins (LDL). Capillary leakage, an early feature of diabetic retinopathy, results in the exposure of retinal pericytes to modified LDL, including glycated (G-LDL) and heavily oxidized glycated LDL (HOG-LDL). We demonstrate here that modified LDL inhibits the proliferation and survival of cultured human retinal pericytes. Modified LDL also induced DNA fragmentation in bovine retinal pericytes. Overall, HOG-LDL produced a significantly higher extent of cytotoxicity and apoptosis in retinal pericytes. These results indicate that exposure of pericytes to HOG-LDL could be implicated in the development of diabetic retinopathy.
