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Am J Ophthalmol. 2015 Jun;159(6):1027-1035.e3. doi: 10.1016/j.ajo.2015.02.008. Epub 2015 Feb 19.

Alteration of galectin-3 in tears of patients with dry eye disease.

Author information

1
Schepens Eye Research Institute and Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts.
2
Campus Bio Medico University of Rome, Rome, Italy.
3
Schepens Eye Research Institute and Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts. Electronic address: pablo_argueso@meei.harvard.edu.

Abstract

PURPOSE:

To investigate the expression, release, and proteolytic degradation of galectin-3 in patients with dry eye disease.

DESIGN:

Observational case series with a comparison group.

METHODS:

Tear washes and conjunctival impression cytology specimens were collected through standard procedures from 16 patients with dry eye and 11 age-matched healthy subjects. Galectin-3 content in tears was analyzed by quantitative Western blot, using recombinant galectin-3 protein to generate a calibration curve. The relative expression of galectin-3 and matrix metalloproteinase 9 (MMP9) was evaluated by quantitative polymerase chain reaction. The cleavage of galectin-3 was studied in vitro using activated recombinant MMP9 and protease inhibitors.

RESULTS:

The concentration of galectin-3 protein in tears, but not galectin-3 expression in conjunctival epithelium, was significantly higher in tears of patients with dry eye (0.38 ng/μg total protein, range 0.04-1.36) compared to healthy subjects (0.12 ng/μg total protein, range 0.00-0.41) (P < .01). By Western blot, an intact (∼28.0 kDa) galectin-3 band was identified in tear samples from healthy subjects, whereas 50% of the dry eye samples were characterized by the additional presence of a partially degraded form (∼25.4 kDa). In our experiments, elevated expression of MMP9 in dry eye subjects correlated with the ability of active MMP9 to cleave galectin-3 from recombinant origin. Interestingly, cleavage of endogenous galectin-3 in tear samples was impaired using a broad-spectrum proteinase inhibitor cocktail, but not the pan-specific MMP inhibitor GM6001, suggesting the presence of proteases other than MMPs in promoting galectin-3 degradation in dry eye.

CONCLUSIONS:

Our results indicate that release of cellular galectin-3 into tears is associated with epithelial dysfunction in dry eye, and that galectin-3 proteolytic cleavage may contribute to impaired ocular surface barrier function.

PMID:
25703476
PMCID:
PMC4426220
DOI:
10.1016/j.ajo.2015.02.008
[Indexed for MEDLINE]
Free PMC Article

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