Construction and mechanism of dry eye model in mice with ocular surface iron overload

Abstract

AIM: To establish a dry eye mouse model of iron overload by intraperitoneal injection of iron dextran and preliminarily explore its possible mechanism.METHODS: A total of 40 male C57BL/6 mice(taking the right eye as the experimental eye)were divided into 4 groups by random number table method: There were 10 mice in the control group, each time by intraperitoneal injection of 0.2mL of normal saline; Low-dose group, middle-dose group and high-dose iron group with 10 mice in each group were the model group. Each time, 0.2mL of iron dextran solution with concentrations of 12.5, 25, and 50 mg/mL was injected intraperitoneally. One injection 3d for a total of 28d. We observed the ocular surface inflammation index, corneal fluorescein staining, tear break-up time(BUT)and Schimer I test(SIt)on the 7, 14 and 28d after injection and evaluated the degree of dry eye and ocular surface inflammation. After 28d, the mice were sacrificed for cornea, conjunctiva and lacrimal glands tissue for HE staining, Prussian blue staining and tissue iron detection, to evaluate the inflammatory reaction and iron overload. The expression of inflammatory factors interleukin-1β(IL-1β), tumor necrosis factor-α(TNF-α)and matrix metallo proteinase-9(MMP-9)were detected by enzyme-linked immunosorbent assay(ELISA).RESULTS: Compared with the control group, the mice in the model group showed a series of dry eye symptoms, the inflammation index of ocular surface in mice were increased, the score of corneal fluorescein staining increased, the BUT shortened and the amount of tear secretion decreased(all P<0.05). The cornea, conjunctiva and lacrimal gland tissues of the mice were damaged to varying degrees, the iron deposition on the eye surface of the model group was more serious than that of the control group, and the iron content of the tissue was significantly increased than the control group(all P<0.01). The contents of inflammatory factors(IL-1β, TNF-α, MMP-9)in the cornea, conjunctiva and lacrimal gland tissue of the mice in the model group were significantly higher than those of the control group(all P<0.01). With the increase of injection time and concentration of iron dextran, the degree of dry eye and ocular surface inflammation in mice gradually increased. CONCLUSION: The mouse iron overload dry eye model was successfully established by intraperitoneal injection of iron dextran, the mechanism may be related to the ocular surface inflammation aggravated by iron overload.

Keywords

• dry eye
• inflammation
• iron overload
• mice
• model