GENISTEIN ALLEVIATES HIGH GLUCOSE INDUCED TOXICITY AND ANGIOGENESIS IN CULTURED HUMAN RPE CELLS

Objective: Genistein, an iso flavonoid has been shown to possess many biological activities including anti-inflammatory, antioxidant and anti-angiogenic property. It has been shown to be protective in dampening diabetes induced retinal inflammation in vivo. Therefore, the purpose of the present study is to investigate the effect of genistein on glucose induced toxicity in cultured human RPE cells (ARPE-19).Methods: ARPE-19 cells were challenged with normal glucose (NG 5 mM) and high glucose (HG1 25 mM & HG2 50 mM) concentrations with or without genistein (20 µM) for 24 h. The mRNA expression of aldose reductase (ALR) and VEGF was measured by real-time PCR using SYBR green. Inhibitory effects upon ALR activity were performed. The VEGF levels of cell supernatant were estimated by sandwich ELISA. Cellular viability and mitochondrial function upon genistein treatment were assessed using dye exclusion method and MTT assay respectively.Results: Genistein at the studied concentration showed 93% of cell viability and no marked toxicity was observed on cell growth. ARPE-19 cells challenged with HG1 and HG2 showed (2.32) and (2.48) fold increase in ALR expression as compared to NG. Significant increase in VEGF165 expression was observed in ARPE-19 cells with HG1 and HG2 as compared to NG. The genistein treated cells significantly reduced the mRNA expression of both ALR and VEGF165. No significant increase in VEGF level was observed in ARPE-19 cell supernatant with HG1 and HG2 (220.68±5.24 and 228.96±7.19 pg/ml) as compared to NG (220.30±2.04 pg/ml), however, significant reduction was observed in response to treatment with genistein in HG1 and HG2 (155.51±9.33 and 122.85±4.76 pg/ml). Also ALR activity significantly reduced in genistein treated cells when compared with HG1 and HG2 concentrations.Conclusion: The results of the present study clearly demonstrate that genistein protects RPE cells from glucose toxicity. Genistein could be a prospective potent agent for treating complications linked with diabetes mellitus, such as diabetic retinopathy.Â

Polymorphisms in sodium-dependent vitamin C transporter genes and plasma, aqueous humor and lens nucleus ascorbate concentrations in an ascorbate depleted setting.

We have previously reported low concentrations of plasma ascorbate and low dietary vitamin C intake in the older Indian population and a strong inverse association of these with cataract. Little is known about ascorbate levels in aqueous humor and lens in populations habitually depleted of ascorbate and no studies in any setting have investigated whether genetic polymorphisms influence ascorbate levels in ocular tissues. Our objectives were to investigate relationships between ascorbate concentrations in plasma, aqueous humor and lens and whether these relationships are influenced by Single Nucleotide Polymorphisms (SNPs) in sodium-dependent vitamin C transporter genes (SLC23A1 and SLC23A2). We enrolled sixty patients (equal numbers of men and women, mean age 63 years) undergoing small incision cataract surgery in southern India. We measured ascorbate concentrations in plasma, aqueous humor and lens nucleus using high performance liquid chromatography. SLC23A1 SNPs (rs4257763, rs6596473) and SLC23A2 SNPs (rs1279683 and rs12479919) were genotyped using a TaqMan assay. Patients were interviewed for lifestyle factors which might influence ascorbate. Plasma vitamin C was normalized by a log10 transformation. Statistical analysis used linear regression with the slope of the within-subject associations estimated using beta (β) coefficients. The ascorbate concentrations (μmol/L) were: plasma ascorbate, median and inter-quartile range (IQR), 15.2 (7.8, 34.5), mean (SD) of aqueous humor ascorbate, 1074 (545) and lens nucleus ascorbate, 0.42 (0.16) (μmol/g lens nucleus wet weight). Minimum allele frequencies were: rs1279683 (0.28), rs12479919 (0.30), rs659647 (0.48). Decreasing concentrations of ocular ascorbate from the common to the rare genotype were observed for rs6596473 and rs12479919. The per allele difference in aqueous humor ascorbate for rs6596473 was -217 μmol/L, p < 0.04 and a per allele difference in lens nucleus ascorbate of -0.085 μmol/g, p < 0.02 for rs12479919. The β coefficients for the regression of log10 plasma ascorbate on aqueous humor ascorbate were higher for the GG genotype of rs6596473: GG, β = 1460 compared to carriage of the C allele, CG, β = 1059, CC, β = 1132, p interaction = 0.1. In conclusion we found that compared to studies in well-nourished populations, ascorbate concentrations in the plasma, aqueous humor and lens nucleus were low. We present novel findings that polymorphisms in SLC23A1/2 genes influenced ascorbate concentration in aqueous humor and lens nucleus