Corneal alkali burns are potentially blinding injuries. Alkali induces oxidative stress in corneas followed by excessive corneal inflammation, neovascularization, and untransparent scar formation. Molecular hydrogen (H2), a potent reactive oxygen species (ROS) scavenger, suppresses oxidative stress and enables corneal healing when applied on the corneal surface. The purpose of this study was to examine whether the H2 pretreatment of healthy corneas evokes a protective effect against corneal alkali-induced oxidative stress. Rabbit eyes were pretreated with a H2 solution or buffer solution, by drops onto the ocular surface, and the corneas were then burned with 0.25 M NaOH. The results obtained with immunohistochemistry and pachymetry showed that in the corneas of H2-pretreated eyes, slight oxidative stress appeared followed by an increased expression of antioxidant enzymes. When these corneas were postburned with alkali, the alkali-induced oxidative stress was suppressed. This was in contrast to postburned buffer-pretreated corneas, where the oxidative stress was strong. These corneas healed with scar formation and neovascularization, whereas corneas of H2-pretreated eyes healed with restoration of transparency in the majority of cases. Corneal neovascularization was strongly suppressed. Our results suggest that the corneal alkali-induced oxidative stress was reduced via the increased antioxidant capacity of corneal cells against reactive oxygen species (ROS). It is further suggested that the ability of H2 to induce the increase in antioxidant cell capacity is important for eye protection against various diseases or external influences associated with ROS production.

• MeSH
• Alkalies toxicity   MeSH
• Antioxidants metabolism   MeSH
• Burns, Chemical drug therapy   metabolism   pathology   MeSH
• Epithelial Cells drug effects   metabolism   pathology   MeSH
• Wound Healing drug effects   MeSH
• Rabbits MeSH
• Disease Models, Animal MeSH
• Corneal Neovascularization prevention & control   MeSH
• Oxidative Stress drug effects   MeSH
• Eye Burns chemically induced   drug therapy   metabolism   pathology   MeSH
• Reactive Oxygen Species metabolism   MeSH
• Cornea blood supply   drug effects   metabolism   pathology   MeSH
• Hydrogen pharmacology   therapeutic use   MeSH
• Animals MeSH
• Check Tag
• Rabbits MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Retracted Publication MeSH
• Names of Substances
• Alkalies MeSH
• Antioxidants MeSH
• Reactive Oxygen Species MeSH
• Hydrogen MeSH

Our previous research revealed that trehalose, a nonreducing disaccharide of glucose and an important stress responsive factor, proved to have anti-inflammatory, antiapoptotic, and particularly antioxidant properties in UVB-irradiated corneas. Trehalose reduced oxidative stress in corneas induced by UVB irradiation, by means of a decrease in the antioxidant/prooxidant imbalance in the corneal epithelium. In this study, we demonstrate that trehalose of 3% or 6% concentration in eye drops directly decreases oxidative stress in UVB-irradiated corneas, by removing the excessive amount of reactive oxygen species (ROS). Trehalose drops applied on corneas during UVB irradiation once daily for four days resulted in a reduction or even absence of the oxidative stress, DNA damage, and peroxynitrite formation (detected by nitrotyrosine residues), seen in buffer-treated corneas. Furthermore, trehalose treatment applied curatively after repeated irradiation for the subsequent fourteen days led to the renewal of corneal transparency and significant suppression or even absence of neovascularization. This was in contrast to buffer-treated irradiated corneas, where the intracorneal inflammation was developed and the untransparent corneas were vascularized. In conclusion, the treatment of UVB-irradiated corneas with trehalose eye drops removed the excessive amount of ROS in the corneal epithelium, leading to the suppression of oxidative stress and favorable corneal healing. The 6% trehalose showed a higher intensive antioxidant effect.

• MeSH
• Wound Healing drug effects   radiation effects   MeSH
• Interleukin-1beta metabolism   MeSH
• Keratins metabolism   MeSH
• Rabbits MeSH
• Oxidative Stress * drug effects   radiation effects   MeSH
• Corneal Injuries drug therapy   MeSH
• DNA Damage MeSH
• Reactive Oxygen Species metabolism   MeSH
• Re-Epithelialization drug effects   radiation effects   MeSH
• Cornea drug effects   pathology   radiation effects   MeSH
• Nitric Oxide Synthase Type II metabolism   MeSH
• Trehalose pharmacology   therapeutic use   MeSH
• Tyrosine analogs & derivatives   metabolism   MeSH
• Ultraviolet Rays * MeSH
• Vascular Endothelial Growth Factor A metabolism   MeSH
• Animals MeSH
• Check Tag
• Rabbits MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Retracted Publication MeSH
• Names of Substances
• 3-nitrotyrosine MeSH Browser
• Interleukin-1beta MeSH
• Keratins MeSH
• Reactive Oxygen Species MeSH
• Nitric Oxide Synthase Type II MeSH
• Trehalose MeSH
• Tyrosine MeSH
• Vascular Endothelial Growth Factor A MeSH

The aim of this study is to examine whether molecular hydrogen (H2) is able to reduce oxidative stress after corneal damage induced by UVB irradiation. We previously found that UVB irradiation of the cornea caused the imbalance between the antioxidant and prooxidant enzymes in the corneal epithelium, followed by the imbalance between metalloproteinases and their physiological inhibitors (imbalances in favour of prooxidants and metalloproteinases) contributing to oxidative stress and development of the intracorneal inflammation. Here we investigate the effect of H2 dissolved in PBS in the concentration 0.5 ppm wt/vol, applied on rabbit corneas during UVB irradiation and healing (UVB doses 1.01 J/cm2 once daily for four days). Some irradiated corneas remained untreated or buffer treated. In these corneas the oxidative stress appeared, followed by the excessive inflammation. Malondiladehyde and peroxynitrite expressions were present. The corneas healed with scar formation and neovascularization. In contrast, in H2 treated irradiated corneas oxidative stress was suppressed and malondiladehyde and peroxynitrite expressions were absent. The corneas healed with the restoration of transparency. The study provides the first evidence of the role of H2 in prevention of oxidative and nitrosative stress in UVB irradiated corneas, which may represent a novel prophylactic approach to corneal photodamage.

• MeSH
• Rabbits MeSH
• Peroxynitrous Acid metabolism   MeSH
• Malondialdehyde metabolism   MeSH
• Oxidative Stress drug effects   radiation effects   MeSH
• Corneal Injuries drug therapy   metabolism   MeSH
• Reactive Oxygen Species metabolism   MeSH
• Cornea drug effects   metabolism   radiation effects   MeSH
• Ultraviolet Rays * MeSH
• Hydrogen therapeutic use   MeSH
• Animals MeSH
• Check Tag
• Rabbits MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Retracted Publication MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Peroxynitrous Acid MeSH
• Malondialdehyde MeSH
• Reactive Oxygen Species MeSH
• Hydrogen MeSH