Osmotic induction of placental growth factor in retinal pigment epithelial cells in vitro: contribution of NFAT5 activity

Abstract

One risk factor of neovascular age-related macular degeneration is systemic hypertension; hypertension is mainly caused by extracellular hyperosmolarity after consumption of dietary salt. In retinal pigment epithelial (RPE) cells, high extracellular osmolarity induces vascular endothelial growth factor (VEGF)-A (Hollborn et al. in Mol Vis 21:360-377, 2015). The aim of the present study was to determine whether extracellular hyperosmolarity and chemical hypoxia trigger the expression of further VEGF family members including placental growth factor (PlGF) in human RPE cells. Hyperosmotic media were made up by addition of 100 mM NaCl or sucrose. Chemical hypoxia was induced by CoCl2. Gene expression was quantified by real-time RT-PCR, and secretion of PlGF-2 was investigated with ELISA. Nuclear factor of activated T cell 5 (NFAT5) was depleted using siRNA. Extracellular hyperosmolarity triggered expression of VEGF-A, VEGF-D, and PlGF genes, and secretion of PlGF-2. Hypoosmolarity decreased PlGF gene expression. Hypoxia induced expression of VEGF-A, VEGF-B, VEGF-D, and PlGF genes. Extracellular hyperosmolarity and hypoxia produced additive PlGF gene expression. Both hyperosmolarity and hypoxia induced expression of KDR and FLT-4 receptor genes, while hyperosmolarity caused neuropilin-2 and hypoxia neuropilin-1 gene expression. The hyperosmotic, but not the hypoxic, PlGF gene expression was in part mediated by NFAT5. The expression of PlGF in RPE cells depends on the extracellular osmolarity. The data suggest that high consumption of dietary salt may exacerbate the angiogenic response of RPE cells in the hypoxic retina via transcriptional activation of various VEGF family member genes.

Comparison of cytokine levels in the aqueous humor of polypoidal choroidal vasculopathy and neovascular age-related macular degeneration patients

“…VEGF-D and VEGF-A had been identified to play an important role in angiogenesis. The previous study reported that the high expression of VEGF-D, in addition to VEGF-A, exacerbated the angiogenic response of retinal pigment epithelium (RPE) cell in nAMD [22]. However, as far as we know, there was few research on the concentration of VEGF-D in PCV, SD = Standard deviation.…”

Comparison of Cytokine Levels in the Aqueous Humor of Polypoidal Choroidal Vasculopathy and Neovascular Age-Related Macular Degeneration Patients

“…VEGF-D and VEGF-A had been identified to play an important role in angiogenesis. The previous study reported that the high expression of VEGF-D, in addition to VEGF-A, exacerbated the angiogenic response of retinal pigment epithelium(RPE) cell in nAMD [22]. However, as far as we know, there was few research on the concentration of VEGF-D in PCV, let alone the comparison of aqueous humor levels of VEGF-D in three groups, even they seldomly distinguished VEGF family such as detecting VEGF-A and VEGF-D respectively [13,16].…”

Potential Interplay between Hyperosmolarity and Inflammation on Retinal Pigmented Epithelium in Pathogenesis of Diabetic Retinopathy

“…Taurine transporter is also involved in the osmoregulation of RPE cells subjected to HOS [ 125 ]. HOS-induced increase in aldose reductase, taurine transporter and AQP5 mRNA levels has been shown to be dependent on TonEBP/NFAT5 transactivation activity, suggesting that targeting TonEBP/NFAT5 could represent a new therapeutic strategy for the treatment of DR [ 120 , 126 , 127 ].…”

“…HOS can modify the RPE secretome by increasing the expression of VEGF [ 42 ], placental growth factor (PlGF) [ 127 ], monocyte chemoattractant protein-1 (MCP-1) [ 96 ], basic fibroblast growth factor (bFGF), and heparin-binding epidermal growth factor-like growth factor (HB-EGF) [ 134 ], interleukin 1β (IL1β), interleukin 18 (IL18), and moderately of epidermal growth factor (EGF), tumor-growth factor β1 (TGF-β1), interleukin-6 (IL6), and interleukin-8 (IL8) [ 134 ]. HOS has been shown to increase both IL1β and IL18 by inducing the priming of the Nod-like receptor protein 3 (NLRP3) inflammasome.…”