Therapeutic Effects of Topical Application of Lycium barbarum Polysaccharide in a Murine Model of Dry Eye

To evaluate the safety and efficacy of polysaccharide (LBP) eye drops in a murine model of dry eye disease (DED). Six- to eight-week-old female C57BL/6 mice were subjected to a combination of desiccating stress (DS) and topical benzalkonium chloride (BAC) to induce DED. Five microliters of LBP eye drops (0.625, 2.5, or 12.5 mg/ml) or PBS was applied topically 3 times per day for 10 days to subsequently test their efficacy. Tear secretion, tear breakup time (TBUT), corneal irregularity, and corneal fluorescein staining scores were measured on days 3 and 10 after treatment. The expression of tumor necrosis factor-alpha (TNF-α) in the cornea was assessed by quantitative (q) RT-PCR on days 10. The ocular irritation of LBP eye drops of corresponding concentrations was evaluated on 10- to 12-week-old female Sprague-Dawley rats. Compared with PBS-treated groups, mice treated with 0.625, 2.5, and 12.5 mg/ml LBP showed a significant improvement in the clinical signs of DED in a dose-dependent manner, including corneal epithelial integrity, corneal regularity, and tear production, as well as significant inhibition of inflammatory cell infiltration and TNF-α expression levels in the cornea. All corresponding concentrations of LBP eye drops revealed no obvious ocular irritation. Topical application of LBP could ameliorate dry eye in a murine model of DED without obvious ocular irritation.