Expression of visual system homeobox 1 in human keratoconus.

Aim: To investigate the expression of visual system homeobox 1 (VSX1) and myofibroblast marker alpha smooth muscle actin (α-SMA) in keratoconus (KC).

Methods: Thirty corneal tissue were collected from KC patients after corneal transplantation and 15 normal donor corneas were obtained. All corneal tissues divided into 4 parts for different detections. Scanning electron microscopy was used to observe the ultrastructure of the specimens. VSX1 and α-SMA localization in cornea tissues was detected using immunofluorescence histochemistry. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot were performed to analyze the expression level of VSX1 and α-SMA.

Results: Compared to normal cornea tissue, the collagen fibers in KC stroma were distortional and attenuated and keratocytes were abnormally changed. VSX1 and α-SMA located in the corneal stroma. The mRNA and protein expression level of VSX1 in KC were about 3 times as high as that of normal tissue (<0.001). α-SMA was hardly expressed in the normal corneas, however, its expression in the KC was about 1.5 times higher than that of the normal corneas (<0.0001).

Conclusion: Compared with normal corneal the expression of VSX1 and α-SMA in KC both increased. VSX1 is related to the activation of keratocytes and involved in the pathogenesis of keratoconus.