ABSTRACT
Objective To investigate pathological changes of lens epithelium cells (LECs) and expressions of matrix metalloproteinase-3 (MMP-3),alpha-smooth muscle actin (α-SMA),and fibronectin (Fn) in lens epithelial cells of experimental diabetic cataract rats,and to evaluate the roles of MMP-3,α-SMA,and Fn in the pathogenesis of diabetic cataract.Methods A total of 105 healthy Sprague-Dawley (SD) rats without lens diseases was randomly divided into normal control (n =45) and diabetic model (n =60) groups.Diabetic model rats were subjected to intraperitoneal injection of streptozotocin (STZ) (60 mg/kg),and those in the normal control group received injection with 0.1 mmol/L citric acid buffer solution of the same volume.The diabetic models were affirmed upon a fasting blood ≥ 16.65 mmol/L at the 3rd days after the injection.Once a week,the changes of blood glucose and body weight were monitored and the progression of cataract formation in both lenses of all rats was recorded with slit lamp observation.At end of 4 weeks,8 weeks,and 12 weeks after STZ injection,lenses were isolated and embedded in paraffin.The LECs histopathology was examined with HE staining.Immunohistochemical method was used to detect expressions of MMP-3,α-SMA,and Fn in normal and diabetic LECs.The related comparisons and statistic analysis were carried out.Results The lenses of control group were always completely transparent throughout the period of experiment with 31.48％,77.78％,and 100％ of lenses in diabetic model group swelling at 4th,8th,and 12th week,respectively.Under the light microscopic level,it has been showed that lens epithelium cells,which was occurred aggregate plaque and arranged in many layers,presented some morphologic characteristics of fibroblasts by HE staining.In control group LECs regularly,MMP-3,α-SMA,and Fn did not express equally;MMP-3,α-SMA,and Fn expressions increased obviously highly,difference had statistical significance compared to diabetic cataract group LECs (P ＜ 0.01).With the development of course of disease,the differences in expression of MMP-3,α-SMA,and Fn were significant between the diabetic cataract LECs and the control group (P ＜ 0.01).During the progression of diabetic cataract,the expression of Fn was positively correlated with that of α-SMA and MMP-3 (r =0.994,P ＜ 0.01;r =0.993,P ＜ 0.01).Conclusions The diabetic cataract liyingbody animal model was established successfully,which has laid down necessary basis to expound the morbidity mechanism of diabetic cataract.In the lens of diabetic cataract group,the expressions of α-SMA,MMP-3,and Fn were significantly increased.They participated in the occurrence and development of diabetic cataract.The expression of Fn was positively correlated with α-SMA and MMP-3.The lens epithelium cells which took on elongated aspect like fibroblast cells appeared epithelial-mesenchymal transformation (EMT),which mediated the occurrence and development of LECs fibrosis.