Alteration of Galectin-3 in Tears of Patients With Dry Eye Disease

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.

Plasma gelsolin promotes re-epithelialization

“…Both events are associated with the release of actin and other intracellular components, for example Galectin-3, into the extracellular space and hence into the tear film 32,33 .…”

Galectin-3 enhances extracellular matrix associations and wound healing in monkey corneal epithelium

“…In contrast, galectin-3 was present in tears from the patients with ocular inflammation, which may have caused release of galectin-3 for self-healing. For example, the level of galectin-3 in tears from dry eye patients is 0.38 ng/μg total protein (Uchino et al, 2015); or 0.76–4.56 μg galectin-3/mL tear assuming 2–12 μg total protein/μL (Ng et al 2000; Li et al, 2010). Since partially degraded galectin-3 has been observed in 50% of patients (Uchino et al, 2015), the in vivo level of intact galectin-3 might be lower than the calculated and effective levels used in our models.…”

Evaluation of galectin-1 and galectin-3 as prospective biomarkers in keratoconus

“…Tear fluid was collected from eyes by pipetting 100 µL of sterile saline into the inferior fornix using a sterile transfer pipette, followed by movement of the eyes to mix the tear fluid content as described 22. Tear samples were promptly frozen at −80°C until the time of analyses.…”