Translocation of pro-apoptotic proteins through basements membrane and hemidesmosome in the corneal epithelium of the keratoconus subjects

Abstract

Keratoconus (KC) is an ectatic corneal disorder to frequently characterize by corneal thinning and severe visual impairment, and it continues to be one of the leading indications for corneal transplantation. The etiology is multi-factorial and pathological changes have been observed in the KC corneas. It is still unknown where the disease originates, but the changes in the corneal epithelium are considered to start even before a clinical sign appears. The present study, we investigated the potential role of basement membrane and hemidesmosomes damage whether they are participating a key role on pro-apoptotic protein elevations in the KC corneal epithelium. Samples of corneal epithelium from three KC and three normal subjects were used by Western blot, electron microscopy, immunohistochemistry and fluorescent staining. The histology and ultrastructural changes in the KC corneal sections were illustrated that arises the damage to the bowmen's layer, hemidesmosomes, and basement membrane broken. The basal cells of the corneal epithelium in KC exhibits squamous cells with absence of nuclei compared to the corneal epithelium of normal subjects. The expression of pro-apoptotic proteins Bax, phospho-p53, and cleaved caspase-3 were elevated significantly in the KC cornea when compared to normal corneal tissues extracts. Similarly, immunohistochemistry and triple antibodies staining (Bax, phosphor-p53, and cleaved caspase-3) of KC subjects were demonstrated an identical result as compared to the normal corneal sections. The Nile red/DAPI stain results correspondingly illustrated that KC corneas had less membrane lipid contents, and occurs a fewer progenitor cells than peripheral corneas in the normal subjects. Hence, the collective results indicate the colocalization of pro-apoptotic proteins transduced through basal epithelial cell damage and fragmented basement membrane, which is boost apoptotic induction in the KC corneal epithelium.