Lectin binding in normal, keratoconus and cross-linked human corneas.

Area of Science:

• Ophthalmology
• Biochemistry
• Glycobiology

Background:

• Human corneal structure and function depend on specific glycosylation patterns.
• Keratoconus is a degenerative corneal disease characterized by progressive thinning and ectasia.
• Cross-linking is a therapeutic approach to strengthen keratoconic corneas.

Purpose of the Study:

• To characterize and compare sugar residue composition in normal, keratoconus, and cross-linked human corneas.
• To investigate the role of altered glycosylation in keratoconus pathogenesis.
• To evaluate the impact of cross-linking treatment on corneal glycosylation patterns.

Main Methods:

• Immunohistochemical localization using a panel of lectins (DBA, SBA, PNA, ConA, WGA, UEA I, GNA, DSA, MAA, SNA).
• Analysis of corneal samples from three groups: normal, keratoconic, and cross-linked keratoconic.
• Application of chemical and enzymatic treatments to refine lectin binding specificity.

Main Results:

• N-acetyl-D-glucosamine and sialic acids increased in keratoconus corneas; L-fucose increased in keratoconus and cross-linked corneas.
• N-acetyl-D-galactosamine was elevated in keratoconus epithelium but absent in keratoconus and cross-linked endothelium.
• D-galactose-(β1-4)-N-acetyl-D-glucosamine was absent in keratoconic stroma and deep layers of cross-linked corneas.

Conclusions:

• Keratoconus is associated with significant alterations in corneal glycosylation.
• Cross-linking treatment partially modifies glycosylation, showing some similarities to normal corneas.
• Sugar residues play a crucial role in maintaining corneal structural integrity, and their alterations may contribute to keratoconus.