Abstract
Purpose:
Dry eye disease (DED) is a common condition causing extreme discomfort, possibly resulting in highly detrimental effects on the quality of life for sufferers. Lactoferrin (LF) has been shown to have a remarkable variety of biological roles, from anti-microbial to anti-tumorigenic properties. Moreover, LF has been shown to have therapeutic effects on age-related lacrimal gland degradation, possibly by the attenuation of excess inflammation and oxidative stress. We hypothesize that LF will provide a preventative effect against the reduced tear secretion caused by stress in a murine model.
Methods:
15, 8 week old C57BL/6JJc1 mice were randomly divided into 3 groups of 5, with each being fed a control diet. The experiment lasted 8 days from day -2 till 5. To observe any changes in tear secretion levels, all mice were subjected to daily tear volume measurements (TVM) via a 15 second thread test. TVM was performed for both eyes and averaged, with a minimum of 10 min interval between the right and left eyes. Initial TVM was performed on days -2, -1 and 0, all prior to the initial stress event of day 0 therefore indicating a “resting tear secretion value”. Daily weight measurements were also taken. From day -2 onwards, following TVM and weight measurement all mice were given a daily oral administration of LF with concentrations varying between the 3 groups: control=0mg/kg, high dose=100mg/kg, low dose=50mg/kg. From day 0 all mice were subjected to restraint and desiccating stress for 4 hours per day for 5 consecutive days, induced by an apparatus formed of tubing and a fan.
Results:
We observed a significant decrease in tear secretion in the control group, whereas both LF administered groups remained near to their initial value. The high dose group displayed marginally higher levels of tear secretion than the low dose. Initial: (average of days -2, -1, 0) control: 2.78mm (SD=0.739), high dose LF: 2.77mm (SD=0.751), low dose LF: 2.93mm (SD=0.666). After first stress event: (day 1) control: 1.15mm (SD=0.530), high dose LF: 2.60mm (SD=0.516), low dose LF: 2.35mm (SD=0.709). Final measurement: (day 5) control: 0.94mm (SD=0.623), high dose LF: 2.50mm (SD=0.548), low dose LF: 2.25mm (SD=0.635).
Conclusions:
Our results have shown that the effects of restraint and desiccating stress on tear secretion are significantly reduced with the oral administration of lactoferrin, possibly by the maintenance of lacrimal gland function.
Keywords: 486 cornea: tears/tear film/dry eye