Expression of mucins MUC5AC and MUC19 on the ocular surface in dry eye syndrome model of ovariectomized female rabbits

Abstract

Background. Dry eye syndrome (DES) is a common symptom of tear film instability and ocular surface damage due to an abnormal quality and quantity of tears, including the sensation of foreign objects and blurred vision. Among all factors for tear film stability, MUC5AC and MUC19 are very important; the levels of both mucins are associated with the pathogenesis of DES. Objectives. The aim of this study was to explore the expression of MUC5AC and MUC19 on the ocular surface in a DES model of ovariectomized female rabbits. Material and methods. Healthy female New Zealand white rabbits (n = 18; age: 1 year, weight: 2.5 ±0.6 kg) were randomly assigned to a test group and a control group. The DES model was constructed in ovariectomized female rabbits. Indicators of ocular surface injury, such as Schirmer’s test, corneal fluorescence staining, a conjunctival imprinting cytology test, and the expression of MUC5AC and MUC19 in conjunctival tissues were evaluated with immunohistochemistry in week 1, week 2 and week 4. Results. Both the length of soaked test paper and the total scores of corneal fluorescence staining at all time-points were significantly lower in the test group than in the control group, and they decreased over time (p < 0.05). The grades of imprinted cells at all time-points were significantly higher in the test group than in the control group, and they increased over time (p < 0.05). The percentage of goblet cells was significantly lower in the test group than in the control group, and it decreased over time (p < 0.05). The percentages of cells with a positive expression of MUC5AC and MUC19 at all time-points were significantly lower in the test group than in the control group, and they decreased over time (p < 0.05). Conclusions. The pathogenesis of DES is associated with an increased grade of imprinted cells, decreased goblet cells, and a decreased expression of MUC5AC and MUC19.