Regional Conjunctival Differences in Glycocalyx Mucin Expression in Dry Eye and Normal Subjects

Area of Science:

• Ophthalmology
• Biochemistry
• Cell Biology

Background:

• The ocular surface is protected by a tear film, which is stabilized by mucins.
• Membrane-associated mucins (MAMs) form the apical surface of conjunctival goblet cells and non-goblet cells, contributing to the tear film's physical and biochemical properties.
• Dry eye (DE) disease is a common condition characterized by discomfort and visual disturbance due to tear film instability.

Purpose of the Study:

• To investigate the regional differences in the expression of MUC1, MUC4, and MUC16 in the conjunctiva of normal and dry eye subjects.
• To understand the potential role of these MAMs in the pathophysiology of dry eye disease.

Main Methods:

• Conjunctival impression cytology was used to collect samples from four distinct regions of the eye in adult subjects with and without dry eye.
• MAMs were extracted and quantified using a capillary electrophoresis nano-immunoassay system.
• Expression levels were normalized to total protein content and analyzed statistically.

Main Results:

• In normal subjects, MUC1 expression was significantly higher in the nasal bulbar conjunctiva compared to superior and inferior regions.
• In dry eye subjects, MUC1 expression was highest in the superior region.
• MUC4 and MUC16 expression was significantly upregulated in both superior and inferior regions of the conjunctiva in dry eye subjects compared to normal subjects.

Conclusions:

• Regional expression patterns of MAMs differ between normal and dry eye states.
• The observed upregulation of MUC1, MUC4, and MUC16 in dry eye may serve to reduce friction between the eyelid and ocular surface during blinking.
• Further research is needed to elucidate the specific functions of individual MAMs in ocular surface health and disease.