Tear Protein Alteration in Dogs with Keratoconjunctivitis Sicca

Area of Science:

• Ophthalmology
• Immunology
• Proteomics

Background:

• Keratoconjunctivitis sicca (KCS) is an immune-mediated canine eye disease causing tear deficiency and inflammation.
• The Schirmer tear test (STT) measures tear quantity, but tear protein qualitative changes in KCS are not well understood.

Purpose of the Study:

• To identify and characterize differentially expressed tear proteins in dogs with KCS.
• To explore the diagnostic potential of the tear proteome in canine KCS.

Main Methods:

• Collected tear samples from Beagles with KCS and healthy controls.
• Utilized two-dimensional electrophoresis and MALDI-TOF-MS for protein separation and identification.
• Measured total protein concentration via UV absorbance.

Main Results:

• Dogs with KCS had significantly higher total tear protein concentrations (30.7 mg/mL) compared to healthy dogs (11.5 mg/mL).
• Five proteins (serum albumin, lactotransferrin isoform 1, immunoglobulin gamma heavy chain C, Can f 1, lysozyme C) were differentially expressed.
• High-molecular-weight proteins were upregulated, while low-molecular-weight proteins were reduced in KCS tears.

Conclusions:

• KCS significantly alters tear protein quantity and quality, impacting tear film homeostasis and ocular defense.
• The tear proteome shows potential as a source for diagnostic and therapeutic biomarkers in canine KCS.