Comprehensive identification of dysregulated extracellular matrix molecules in the corneal endothelium of patients with Fuchs endothelial corneal dystrophy

Fuchs endothelial corneal dystrophy (FECD) is a bilateral, progressive corneal endothelial disease characterized by the formation of extracellular matrix (ECM) excrescences called guttae. This study integrated proteomic and transcriptomic analyses to elucidate the molecular composition and spatial organization of ECM proteins in the Descemet membrane (DM) of FECD patients. Through shotgun proteomics of FECD-derived DM specimens and RNA sequencing data from FECD (n = 10) and control (n = 7) corneal endothelial cells, we identified 19 significantly upregulated molecules in FECD, including 13 ECM-related proteins. Gene Ontology and Reactome analyses revealed ECM-related pathways as central to FECD pathology. Immunofluorescence analyses of flat-mounted and cross-sectional specimens from FECD patients undergoing Descemet membrane endothelial keratoplasty (DMEK) and controls demonstrated distinct spatial patterns for six ECM proteins. Fibronectin and collagen VI α1 were detected on the outer surfaces of guttae, matrilin-3 and biglycan localized around guttae, while LTBP2 and tenascin were strongly associated with the posterior fibrillar layer (PFL). The peripheral corneal regions predominantly exhibited scattered guttae, whereas the central region displayed buried guttae encapsulated by ECM deposition. This study comprehensively examined ECM protein expression patterns, revealing distinct spatial distributions across guttae, PFL, and surrounding DM regions. These findings suggest that clinical assessments should incorporate both guttae confluence and the presence of ECM-rich PFL to achieve a more comprehensive understanding of FECD progression, thereby informing more accurate staging and optimal surgical planning.