Antioxidant protection in cultured corneal cells and whole corneas submitted to UV-B exposure

Abstract

Several corneal pathologies are characterized by the presence of reactive oxygen species (ROS); therefore, we evaluated the protection afforded by pirenoxine and melatonin to corneal cell culture and whole rabbit cornea from ultraviolet exposure and other oxidant systems.Rabbit cornea cell (SIRC) plates and whole corneas were exposed to UV-B (80 or 800 mJ/cm 2 ) or incubated with fMLPstimulated autologous macrophages, in the presence or absence of pirenoxine or melatonin (10 À5 M). The protective activity of compounds was assessed by measuring superoxide anion formation, inhibition of oxidation and mitochondrial viability. Moreover the ex vivo protective effect of pirenoxine and melatonin was verified in the whole cornea submitted to UV-B exposure in vitro.Our experimental data demonstrate that pirenoxine and melatonin were able to inhibit the superoxide formation and oxidative effect in cell culture and whole rabbit corneas submitted to UV-B exposure or to incubation with fMLP-stimulated autologous macrophages.Mitochondrial viability was restored in epithelial cells of rabbit cornea but not in SIRCs. Moreover, both compounds are also able to increase ex vivo epithelial corneal cell defences against the in vitro UV-B induced lipid peroxidation.

Pirenoxine prevents oxidative effects of argon fluoride excimer laser irradiation in rabbit corneas: biochemical, histological and cytofluorimetric evaluations

“…In our hypothesis, the neutralization of these seeding events prevents the damage to mitochondrial apparatus and the unbalance of the cell oxidoreductase system, thus inhibiting the avalanche multiplication of ROS and their consequent effects. This is consistent with the protection provided by pirenoxine in preserving mitochondrial viability and scavenging capability of corneal cells exposed to 800 mJ/cm 2 UV-B [36]. Moreover, histological results show that the compound can improve antioxidant defenses, thus inhibiting stromal extracellular vacuolization and preserving natural stroma morphology.…”

“…This incubation was performed for 2 h in the presence or absence of 10 À5 M pirenoxine and, after washing, for 18 h in PBS. Such a concentration of the active principle was selected on the basis of its proven effectiveness to inhibit lens homogenate lipid peroxidation and prevent corneal damage due to UV-B radiation [35,36]. Basal values were obtained by identical treatment of eyes without the ArF irradiation and without pirenoxine.…”

“…In our recent studies on this active molecule, we have proved that the scavenging activity of the compound is selectively directed to the neutralization of hydroxyl radicals and is therefore able to reject various induced oxidative attacks on the lenses in vitro, ex vivo and in vivo [35] and to protect corneal tissue exposed to UV-B light in vitro and ex vivo [36]. Moreover, we have demonstrated that the pirenoxine efficacy as scavenging molecule is at least comparable or in several tests higher than that exerted by other well known antioxidant compounds (i.e., vitamin E, melatonin and 21-aminosteroid U74500A; [35,36]). The demonstration of a similar protective effectiveness against corneal oxidation stress following ArF excimer laser irradiation could extend the use of this compound to the preventive treatment of the cornea before and after PRK surgical intervention.…”

Arsenite pre‐conditioning reduces UVB‐induced apoptosis in corneal epithelial cells through the anti‐apoptotic activity of 27 kDa heat shock protein (HSP27)

“…Besides breaking DNA bonds through high-energy radiation, UVB may cause cellular damage through generation of reactive oxygen species (ROS). In corneal epithelial cells, UVB irradiation at levels comparable to physiologic solar exposure increases the levels of ROS such as superoxide anions (Shimmura et al, 1996;Ciuffi et al, 2003). DNA injury and generation of ROS then initiate a highly complex process to induce apoptotic cell death (Kulms and Schwarz, 2002).…”

“…This situation has prompted considerable interest in the development of novel UVB protective approaches. Protection of cornea from UVB exposure with antioxidants has been investigated (Jones et al, 1999;Ciuffi et al, 2003). Induction of heat shock proteins has been recently proposed as another novel mechanism (Jones et al, 2003).…”