Protective effects of fluoroquinolones on UV-induced damage of cultured ocular cell lines

Although the fluoroquinolones have strong antibacterial effects, some of them also have adverse ocular effects such as diplopia, uveitis, optic neuropathy, and retinal detachment. The purpose of this study was to determine whether low concentrations of fluoroquinolones can lessen the cytotoxic effects of ultraviolet (UV) light on different kinds of cultured ocular cells. We studied cultured human corneal endothelial cells (HCECs), a retinal ganglion cell line (RGC-5), a mouse-derived photoreceptor cell line (661W), a human adult retinal pigment epithelial cell line (ARPE-19), primary retinal cells, and primary human RPE cells. Levofloxacin, ciprofloxacin, and clinafloxacin were selected as the fluoroquinolones to test. The viabilities of the 661W, ARPE-19, and hRPE cells were assessed by Cell Counting Kit-8, and that of HCECs, 661W cells, and ARPE-19 cells by double fluorescent staining with Hoechst 33342 and propidium iodide (PI). Damage of retinal primary culture cells was assessed by immunostaining. Intracellular production of reactive oxygen species was measured in ARPE-19 cells by CM-H₂DCFDA after UV light exposure. An activation of caspase by UV light in ARPE-19 cells was detected with a caspase-3/7 assay kit. UV exposure increased the number of dead cells, and the three fluoroquinolones tested suppressed this increase. Fluoroquinolones also protected the cells against the hydroxyperoxide (H₂O₂)-induced cell damage. Moreover, the fluoroquinolones decreased the production of reactive oxygen species and the activity of caspase-3/7, and low concentrations of fluoroquinolones reduced the oxidative stress in cultured ocular cell lines. We conclude that fluoroquinolones may have protective effects in these cells against UV exposure.