Human Xylosyltransferase-1: A New Marker for Corneal Fibrosis Detection

Abstract

Purpose : Corneal scarring (fibrosis) is characterized by the de novo formation of myofibroblast and extracellular matrix including proteoglycans. Human xylosyltransferase-1 (XT1) has been found to catalyze glycosaminoglycan biosynthesis at fibrotic onset in non-ocular tissues, however its expression and role in normal and fibrotic corneas is still unknown. We tested the hypothesis that XT1 can serve as a biomarker for corneal fibrotic remodeling. The specific aims were to: 1) characterize XT1 expression in normal and wounded human and rabbit corneas, 2) investigate its role in corneal wound healing, and 3) determine whether XT1 can serve as a biomarker for corneal fibrosis.

Methods : The normal and injured corneas of the New Zealand White rabbits under approved IACUC and donor human corneas (normal and diseased) exempt from IRB were used. Primary corneal fibroblast (HCF) and myofibroblast (HMF) cultures generated from normal donor human corneas were also used. HMF were produced by growing HCF in 5ng/ml transforming growth factor-β1 (TGFβ1) for 72h under serum-free conditions. Immunofluorescence, H&E, immunoblotting, and real-time quantitative PCR analyzed mRNA and protein levels of selected genes. The α-smooth muscle actin (αSMA), a well acceptable myofibroblast marker in corneal field, was used as a control in comparative studies.

Results : Normal rabbit and human corneas showed no expression of XT1 and αSMA. Conversely, wounded (alkali burn and photorefractive keratectomy applied) rabbit corneas showed significantly high levels of XT1 and αSMA mRNA expression (p<0.01). Immunofluorescence detected significant number of αSMA+ and XT1+ cells in wounded rabbit corneas than uninjured corneas. It is note that XT1 mRNA levels were >100 folds higher than the αSMA. TGFβ1 treated HCF showed significantly higher levels of XT1 and αSMA mRNA levels compared to untreated HCF (p<0.01). HMF cultures showed much greater levels of XT1 compared to αSMA mRNA (5-35 fold; p<0.01) in time-dependent manner (4h-7days).

Conclusions : XT1 may serve as a biomarker for corneal fibrosis. Future studies will test the potential of XT1 for mitigating corneal scarring.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.