Cristina M Kenney

Effects of hydroquinone on retinal and vascular cells in vitro

Aim: To explore the molecular pathophysiology that might explain the epidemiologic association between cigarette smoke and age-related macular degeneration (AMD) by examining the effects of hydroquinone (HQ), a toxic compound present in high concentration in cigarette smoke-related tar, on human retinal pigment epithelial cells (ARPE-19), rat retinal neurosensory cells (R-28), and human microvascular endothelial cells (HMVEC). Materials and Methods: ARPE-19, R-28, and HMVEC were treated for 24 h with four different concentrations of HQ (500 μM, 200 μM, 100 μM, 50 μM). Cell viability, caspase-3/7 activation, DNA laddering patterns, and lactate dehydrogenase (LDH) levels were analyzed. Results: At 50 μM HQ, R-28 cells showed a significant decrease in cell viability compared with the dimethyl sulfoxide (DMSO)-treated controls. At the 100–500 μM concentrations, all three cell lines showed significant cell death (P < 0.001). In the ARPE-19, R-28, and HMVEC cultures, the caspase-3/7 activities were not increased at any of the HQ concentration. Conclusion: Our findings suggest that the mechanism of cell death in all three cell lines was through non-apoptotic pathway. In addition, neuroretinal R-28 cells were more sensitive to HQ than the ARPE-19 and HMVEC cultures.

Protective effects of 17β-estradiol on Benzo(e)pyrene[B(e)P]-induced toxicity in ARPE-19 cells

Purpose: The aim of this study was to examine the effect of 17β-estradiol on Benzo(e)pyrene [B(e)P]-induced toxicity in ARPE-19 cells. Methods: We pretreated ARPE-19 cells with 20 nM and 40 nM 17β-estradiol for 6 hours, followed by addition of 300 μM B(e)P for additional 24 hours. Cell viability was measured using Trypan blue dye-exclusion assay. JC-1 assay was performed to measure mitochondrial membrane potential (ΔΨm). For a quantitative estimation of cell death, apoptotic markers such as caspase-3/7, caspase-9, and caspase-12 were measured. Results: Our results demonstrated that when treated with B(e)P, the viability and ΔΨm of ARPE-19 cells declined by 25% and 63%, respectively (P < 0.05). However, pretreating with 17β-estradiol increased the viability of ARPE-19 cells by 21% (20 nM) and 10% (40 nM) (P < 0.05). Furthermore, the significantly reduced ΔΨm in βE+B(e)P treated cells ARPE-19 cells was restored by pre-treatment with 17β-estradiol- ΔΨm was increased by 177% (20 nM) and 158% (40 nM) (P < 0.05). We further observed a significant up-regulation in the activity of Caspases-3/7, -9, and -12 in B(e)P-treated ARPE-19 cells. However, 17β-estradiol treatment significantly reduced the activity of all apoptotic markers (P < 0.05). Conclusion: In conclusion, our results demonstrate that 17β-estradiol protects ARPE-19 cells against B(e)P-induced toxicity by decreasing apoptosis, preventing cell death, and restoring mitochondrial membrane potential.