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N. Tirgan, P. Gupta, G. Kulp, A. Boretsky, E. van Kuijk, B. F. Godley, R. G. Tilton, M. Motamedi; Additive Effect of Nicotine and Hyperglycemia on Upregulation of Vascular Endothelial Growth Factor and Inflammation in Human Retinal Pigment Epithelial Cells and Retinal Endothelial Cells. Invest. Ophthalmol. Vis. Sci. 2010;51(13):70.
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© ARVO (1962-2015); The Authors (2016-present)
Previous studies have reported that hyperglycemia and nicotine exposure individually can cause alterations in retinal cell function and proliferation. Much less is known about the combined effect of nicotine exposure with hyperglycemia in the retina. Here, we studied the expression of vascular endothelial growth factor (VEGF) and inflammatory responses of two cell types, ARPE-19 (human retinal pigment epithelial cells) and ACBRI-181 (human retinal microvascular endothelial cells), after simultaneous exposure to both nicotine and hyperglycemia.
ARPE-19 cells and ACBRI-181 cells were exposed to four experimental conditions, including: i) 5 mM glucose, ii) 30 mM glucose, iii) nicotine at concentrations ranging from 10^-4 to 10^-10 M, and iv) a combination of 30 mM glucose and nicotine. Cells were exposed to physiological glucose (5 mM) or hyperglycemia (30 mM) for two days, followed by treatment with nicotine or combination of nicotine and hyperglycemia for an additional 48 hours. Cell proliferation was assessed by MTT assay after five days. The extent of NF-kB activation was assessed using immunocytochemistry to measure RelA nuclear localization after five days. VEGF, MCP-1, and IL-8 were measured from cell culture supernatant using Millipore’s human cytokine kit at baseline, 8, 24, and 48 hours.
ACBRI-181 cell proliferation occurred in the hyperglycemia, nicotine, and combination treatment. The hyperglycemia-treated cells had the greatest proliferation as compared to control (176 %). Cells treated with nicotine at doses of 10^-6 M had exhibited increased proliferation (161% with 5 mM glucose, 159% with 30 mM glucose as compared to control). In addition, increased nuclear localization of RelA accompanied combinational treatment compared to normal glucose-exposed cells. Also, increases in VEGF, MCP-1, and IL-8 were observed when ARPE-19 and ACBRI-181 cells were exposed to a combination of nicotine and hyperglycemia.
The combination of nicotine and hyperglycemia promoted upregulation of VEGF and inflammatory responses in both cell lines. In addition, RelA activation was stronger for the combination treatment, suggesting an additive effect on inflammation. These results suggest that in diabetic patients who smoke, the retinal tissue may experience increased production of VEGF and NF-kB-linked cytokines due to the potential additive effects of chronic exposure to hyperglycemia and nicotine.
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