ABSTRACT
BACKGROUND: Nuclear factor-kappa B (NF-κB) plays a key role in regulating expressions of cytokines and adhesion factors during transcription and in central adjustment during corneal graft rejection reaction.OBJECTIVE: To study the dynamic expressions of NF-κB, intercellular adhesion molecular 1 (ICAM-1) and vascular endothelial growth factor (VEGF) in corneal graft and to investigate the interventional effect of cyclosporin A (CsA). DESIGN, TIME AND SETTING: A randomized controlled animal study was performed in the Department of Ophthalmology, Zhujiang Hospital, the First Military Medical University of Chinese PLA between January and July 2005.MATERIALS: 40 SD rats and 50 Wistar rats were included and randomly divided into three groups, syngenic transplantation (10 Wistar rats used as donor and another 20 Wistar rats used as acceptor), allogeneic transplantation (10 Wistar rats used as donor, and 20 SD rats used as acceptor), and allogeneic transplantation+CsA treatment (10 Wistar rats used as donor, and 20 SD rats used as acceptor).METHODS: Comeal transplantation models were established. Gentamicin (2 000 U) was subconjunctivally injected into the experimental eyes of all ecceptors every other day for three times in total; chloroptic (2.5 g/L) was then used two droplets every time, twice a day, and 18 successive days in total; additionally, tropicamide (5 g/L) was also used two droplets every time, once a day, and 7 successive days in total. One day after corneal transplantation, CsA eye droplet (10 g/L) was used in the allogeneic transplantation+CsA treatment group two droplets every time, three times a day, and 18 successive days in total.MAIN OUTCOME MEASURES: Scores of corneal graft rejection reaction index were measured at day 3, 7, 12, and 18 after corneal transplantation; pathological changes of corneal graft were observed at the same time points to detect expressions of NF-κB, ICAM-1, and VEGF.RESULTS: Rejection reaction was not observed in the syngenic transplantation group at 18 days; however, indexes of rejection reaction in the allogeneic transplantation group were higher than those in the syngenic transplantation group at four time points (P<0.05), but indexes in the allogeneic transplantation+CsA treatment group were lower than those in the allogeneic transplantation group (P<0.05). Immunohistochemical examination indicated that NF-κB, ICAM-1, and VEGF were located at corneal epithelial lamina and substantia propria layer and in newborn vascular endothelial cells. At each time point, expressions of NF-κB, ICAM-1, and VEGF in the allogeneic transplantation group were higher than those in the syngenic transplantation group (P<0.05) but lower than those in the allogeneic transplantation+CsA treatment group (P<0.05).CONCLUSION: CsA can weaken nuclear translocation and activity of NF-κB to inhibit expressions of cytokines, adhesion molecules, and other relative factors so as to inhibit ccurrence and development of corneal graft rejection reaction.
ABSTRACT
BACKGROUND:Corneal neovascularization not only seriously affects vision, it is also a high-risk factor for the rejection after allogeneic ceratoplasty, thus it is always a hot issue and in ophthalmology to investigate the pathogenesis of corneal neovascularization and the inhibitors for blocking its formation.OBJECTIVE: To induce model of corneal neovascularization in rats using nylon suture, and investigate the mechanism of nuclear factor-кB (NF-кB) in the occurrence and development of corneal neovascularization using dexamethasone as the glucocorticoid inhibitor for corneal neovascularization.DESIGN: A randomized controlled trial.SETTING: Department of Ophthalmology, Zhujiang Hospital of Southern Medical University.MATERIALS: The experiments were carried out in the Zhujiang Hospital of Southern Medical University from January to April 2005. Fifty-five healthy male Wistar rats of clean degree were used. Rabbit-anti-rat NF-кB P65 monoclonal antibody, rabbit-anti-rat vascular endothelial growth factor (VEGF) and intercellular adhesion molecule-1 (ICAM-1)monoclonal antibodies, and 3,3-diaminobenzidine (DAB) kit were purchased from Wuhan Boster Biological Technology Co., Ltd.METHODS: ① Interventions: The rats were randomly divided in the saline control group (n =25), dexamethasone group(n =25) and normal comea group (n =5). Corneal neovascularization using nylon suture was induced in rats in the saline control group and dexamethasone group, and then saline and dexamethasone was dropped to the right eye of the rats respectively, 2 drops for each time, 3 times a day for 18 days. Not any treatment was given to the rats in the normal cornea group. ② Evaluations: The score of corneal neovascularization was evaluated in the saline control group and dexamethasone group at 1, 3, 7, 12 and 18 days postoperatively. Corneal sections were prepared to observe the histological changes of cornea under light microscope; The expressions of NF-кB, VEGF and ICAM-1 were detected with immunohistochemical staining.MAIN OUTCOME MEASURES: ① Score of corneal neovascularization; ② Histological changes of cornea; ③ Expressions of NF-кB, VEGF and ICAM-1 in cornea.RESULTS: ① Score of corneal neovascularization: The corneal neovascularization was obviously inhibited, and scores of corneal neovascularization at different time points were all significantly lower than those in the saline control group (P ＜0.05-0.01). ② Histological changes of cornea: In the dexamethasone group, corneal neuvascularization and the infiltration of inflammatory cells after suture were obviously alleviated as compared with those in the control group, and the corneal structures in each layer were relatively complete. ③ Expressions of NF-кB, VEGF and ICAM-1 in cornea: In the dexamethasone group, the expressions of NF-кB, VEGF and ICAM-1 at each time points were all lower than those in the saline control group (P ＜ 0.05). The intensity of the expression of NF-кB was positively correlated with the score of corneal neovascularization and the expressions of ICAM-1 and VEGF (r =0.961, 0.922, 0.958, P ＜ 0.01).CONCLUSION: NF-кB is involved in the formation of corneal neovascularization possibly through upregulating the expressions of its downstream genes (VEGF, ICAM-1). Dexamethasone can inhibit the expressions of many factors related to corneal neovascularization regulated by NF-кB, including cytokines and adhesion molecules, through reducing the activity of NF-кB, and then suppresses the occurrence and development of corneal neovascularization.