Glial Fibrillary Acidic Protein (Gfap) Expression During Cornea Wound Healing Enhanced By Vitamin B12 Topical Application

The cornea is a highly innervated tissue, exhibiting a complex nerve architecture, distribution, and structural organization. Corneal trauma and infection, refractive surgery can cause neurotrophic changes in the cornea. Glial fibrillary acidic protein (GFAP) is an intermediate filament protein that is expressed by numerous cell types of the central nervous system and its expression was also detected in corneal satellite glial cells. Increased GFAP production is an indicator of glial reactivity and biomarker of the process of immune inflammation. Therefore, the pharmacological modulation of nerve-supporting cell response can be beneficial for eliciting neural regeneration after corneal injury.

Bogomolets National Medical University

Palladin Institute of Biochemistry of NAS of Ukraine

Male "Chinchilla" rabbits were kept and treated humanely and in accordance with the Association for Research in Vision and Ophthalmology. Rabbits were randomly divided into three groups of 6 rabbits each. Group I – healthy control, Group II - corneal alkali burn, Group III - corneal alkali burn treated by vitamin B12 during 14 post-traumatic days. GFAP expression levels in corneas were analysed by Western blot after termination of experiment. Additionally, the effects of B12-based treatment on corneal neovascularization were monitored according to Efron scale. The results of immunoblots were analysed densitometrically and presented as mean (M) ± SEM (m). The P value of less than 0.05 was considered significant (one-way ANOVA).

Western blot of corneal tissue lysates revealed a single immunoreactive GFAP band of apparent Mm 49 kDa. In control, intact polypeptide 49 kDa was found in relatively low basal level. However, burn injury upregulated GFAP level in the rabbit corneal tissue by 3.73 folds as compared with the control (P<0.01), while B12 topical application reduced GFAP expression near normal value (decrease by 2.85 folds vs. Burn group, P<0.01). These findings indicate that burn injury overactivates corneal satellite glial cells in response to impact that can be harmful for neuronal function. It was found that B12-based treatment significantly alleviated injury-induced activation of glial response and reduced corneal neovascularization caused by alkali burn.

B12 treatment significantly alleviated injury-induced activation of glial response that may be an important sign of neuroprotection. Thus, application of B12-containing medications can be a useful supplementary to improve recovery of the cornea after ocular trauma or damage, inflammation, or refractive therapy by stimulating corneal wound healing, neuroprotection, and restoring corneal homeostasis.