Intermediate filament expression by normal and diseased human corneal epithelium

Area of Science:

• Ophthalmology
• Cell Biology
• Immunohistochemistry

Background:

• Cicatricial conjunctivitis, resulting from systemic or local disorders, often leads to visual loss due to corneal epithelial changes.
• The exact cause of these corneal epithelial anomalies in cicatricial conjunctivitis remains poorly understood.
• Current theories suggest conjunctival epithelium encroachment onto the cornea, but this is debated.

Purpose of the Study:

• To investigate the origin of corneal epithelial anomalies in cicatricial conjunctivitis.
• To differentiate between conjunctival and corneal epithelial cell origins using immunohistochemical markers.
• To clarify the pathophysiology of visual loss in cicatricial conjunctivitis.

Main Methods:

• Immunohistochemical analysis of cytokeratin expression in normal and pathological corneal and conjunctival specimens.
• Comparison of cytokeratin 3 (CK 3) and cytokeratin 19 (CK 19) expression patterns.
• Examination of specimens from patients with Stevens-Johnson syndrome, cicatricial pemphigoid, and chemical burns.

Main Results:

• Normal corneal epithelium expresses CK 3 and not CK 19.
• Normal conjunctival epithelium expresses CK 19 and not CK 3.
• Transposed conjunctiva retained its native cytokeratin expression pattern.
• In cicatricial conjunctivitis cases, corneal epithelium predominantly showed the normal corneal cytokeratin pattern (CK 3 positive, CK 19 negative).

Conclusions:

• Conjunctival encroachment is not the cause of corneal epithelial changes in cicatricial conjunctivitis.
• The abnormal corneal epithelium in these conditions arises from native corneal cells, not conjunctival cells.
• This finding clarifies the cellular origin of corneal pathology in cicatricial conjunctivitis, impacting understanding of visual loss mechanisms.