Investigating the role of the fibrillar layer in Fuchs endothelial corneal dystrophy

Abstract

Purpose : Recent studies from our laboratory demonstrate that a fibrillar layer (FL) consisting of a collagen I (COL I)-,collagen III (COL III)- and collagen IV (COL IV)-rich matrix exists in the central endothelium of the majority of advanced Fuchs endothelial corneal dystrophy (FECD) patients and that there is a significant decrease in endothelial cell density in this FL region. The present study sought to investigate the role of the FL in advanced FECD in more detail.

Methods : Ingenuity pathway analysis (IPA) was performed in a previously generated data set after RNA sequencing in the corneal endothelium of advanced (modified Krachmer grade 5+6) FECD patients (n=14) and controls (n=10). Differential expression of selected genes was confirmed using quantitative real-time PCR and the expression of the proteins localized in explanted Descemet endothelium complexes (DEC) using immunofluorescence flatmount staining. Cell-culture experiments in a human corneal endothelium derived cell line (HCEC-12) investigated the influence of Transforming Growth Factor Beta (TGF-β) stimulation and altered growth on FL specific collagen coatings in vitro.

Results : IPA identified hepatic fibrosis/hepatic stellate cell activation as the most strongly affected signaling pathway and TGF-β as the top upstream regulator in the corneal endothelium of advanced FECD patients. QPCR and immunofluorescence confirmed differential expression of fibrosis/ TGF-β-related genes (including Collagen V (COL V), Secreted Protein Acidic And Cysteine Rich (SPARC), and Platelet Derived Growth Factor-C (PDGF-C)) and altered protein expression pattern in advanced FECD DECs compared to normal. TGF-β stimulation induced overexpression of fibrosis related targets whereas growth experiments showed decelerated growth on FL related collagens.

Conclusions : This study provides further evidence that activation of the TGF-β signaling cascade and a fibrotic response play a role in the development of the FL. Subendothelial deposits formed during this reaction may contribute to a concomitant toxic microenvironment.

This is a 2021 ARVO Annual Meeting abstract.