Corneal NF-κB activity is necessary for the retention of transparency in the cornea of UV-B-exposed transgenic reporter mice

Abstract

To determine the dynamics of Nuclear Factor-κB (NF-κB) in murine corneal pathology and the role of NF-κB in maintaining corneal clarity after ultraviolet B radiation insult, transgenic mice containing NF-κB- luciferase reporter were exposed to LPS (bacterial lipopolysaccharide), TNF-α (Tumor Necrosis Factor-alpha) or 4 kJ m −2 UV-B radiation. NF-κB decoy oligonucleotides were also administered in some of the UV-B experiments. Following various exposure times, the mice were sacrificed and whole eyes or corneal tissues were obtained. Whole eyes were examined for scattering using a point-source optical imaging technique. Tissue homogenates were examined for luciferase activity using a luminometer. TNF-α and LPS-injected NF-κB-luciferase transgenic mice demonstrated 3–10-fold increases in cornea NF-κB with peak activities at 4 and 6 hr post-injection, respectively. Mice exposed to 4 kJ m −2 UV-B exhibited a 3-fold increase in NF-κB activity 4 hr post-exposure. The administration of NF-κB-decoy oligonucleotides to mice had the effect of reducing UV-B-induced NF-κB activity in the cornea and significantly increasing the amount of light scattering in UV-B exposed corneas 7 days post-UV-B exposure when compared to sham injected mice. These results indicate that NF-κB is activated in cornea in pathologies that involves increased plasma levels of LPS and TNF-α, as well as direct UV-B exposure, and suggest that NF-κB activation play an essential part in the corneal healing process.