The Experimental Study On Mechanisms Of The Complicated Cataract Following Vitrectomy

Objective:Throug the study of the changes of oxygen concentration and the release of inflammatory factors in the anterior chamber; the morphologic changes of lens fiber cells observed by pathological examination; the apoptosis of lens fiber cells detected by TUNEL technique; the expression of caspase-8 determined by immunohistochemistry; the DLAD gene expression with RT-PCR and gene expression profile of lens with microarrays after vitrectomy, to explore the mechanisms of the complicated cataract After vitrectomy.Methods:This study includes five sections. Section 1:Sixty-three Dutch Belted rabbits were randomly divided into 3 groups. One eye of each rabbit underwent partial vitrectomy and Vitreous cavity was replaced by balance salt solution (BSS) or 20% perfluoropropane gas(C3F8) or silicone oil. The intraocular pressures were measured with tonometer and the lens shape were observed with slit lamp microscope. Section 2:The aqueous was obtained by acupuncture at 1d,3d,7d,1m,3m after surgery.The oxygen concentration and inflammatory factors(IL-2,TNF-α) were measured. Section 3:Two eyes were randomly selected and lens extracted in each group at 1d,3d,7d,1m,3m after surgery. Morphologic changes of lens fiber cells were observed by pathological examination. Apoptosis of lens fiber cells was detected by TUNEL technique, and quantified by calculating the apoptotic index (AI). The expression of Caspase-8 was determined by immunohistochemistry. Section 4:Half-quantity reverse transcription polimerase chain reaction (RT-PCR) was employed to detect the DLAD mRNA in lens at 1d,3d,7d,1m,3m after vitrectomy. Section 5:After vitrectomy 18 rabbits were subdivided into 3-day group,1-month group and 1-month group according to their sacrificing time. The genetic expression profile of lens tissue was detected with microarrays.Results:The animal model of the complicated cataract after vitrectomy was established successfully. The DLAD gene expression was all decreased in the three groups. The oxygen concentration and inflammatory factors(IL-2,TNF-α) were all increased in different degrees. The lens fibre nuclei had a more spherical form and increased apoptosis on the lens fiber cells was detected. Caspase-8 was expressed clearly, while DLAD gene expression was decreased. According to the results of gene chips, the changeable genes were involved in the function of oxidative stress, inflammatory, transport, signal, apoptosis, differentiation of cell and real-time PCR proved the results of gene chips were reliable.Conclusions:The changes of crystalline lens microenvironment after vitrectomy which can induce the breakdown or interference of some regulation mechanism makes the process of apoptosis increasing, while the degradation of organel decreased. So the dynamic equilibrium of cell organ of crystalline fiber is broken, which may result in cataract generating. Numerous genes are involved in the development of the complicated cataract after vitrectomy. This study elucidates the influence factors and the molecular mechanisms of the complicated cataract following vitrectomy through various kinds experiments with animal model so as to establish the theory foundation for the complicated cataract treatment.