Abstract
Purpose: :
To evaluate corneal apoptosis in a novel murine model of neurotrophic keratopathy.
Methods: :
6 to 8 week-old male C57BL/6 mice (5 animals) underwent Trigeminal Stereotactic Electrolysis (TSE) in the brain - a procedure we developed to ablate the ophthalmic branch of the trigeminal nerve. Denervation was confirmed by clinical follow-up with digital pictures of the cornea, absence of blink reflex, and reduced β3 tubulin immunohistochemistry for corneal nerves. After 7 days cross-sections of the treated eye were done and stained with TUNEL (Terminal deoxynucleotidyl transferase dUTP nick end labelling) technique for apoptosis.
Results: :
Increased TUNEL expression was observed after 7 days in the treated eye. Apoptosis was detected throughout the cornea as epithelial, keratocyte and endothelial cells were stained. In the contralateral eye, only minimal background apoptosis (mainly located in superficial corneal layers) was detected. A progressive corneal degeneration developed after denervation. 48 hours later animals developed a punctate keratopathy which progressively progressed. Corneal epithelial thickness was reduced by approximately 50%. When blink reflex was absent, corneal nerves disappeared 48 hours after the procedure. The contralateral eye remained normal, and animals did not show neurologic deficits.
Conclusions: :
This study indicates that apoptosis is increased in our animal model of neurotrophic keratitis. Our findings support previous reports on the importance of nerves in corneal and ocular surface health. We believe that our model could be a useful tool to dissect interactions between nerves and different cellular populations of the cornea, as well as evaluate the role of nerves in regulating immune homeostasis of the ocular surface.
Keywords: keratitis • neuropeptides • cornea: basic science