The Expression And Significance Of PN And VEGF In Retina Of Early Diabetic Rats

Research BasicsThe leading causes of visual impairment in diabetic retinopathy(DR)are diabetic macular edema(DME)and proliferative diabetic retinopathy(PDR).A variety of growth factors and inflammatory factors participate in the pathogenesis of DR.Among them,vascular endothelial growth factor(VEGF)plays an important role in the development of DR,especially in the development of DME and PDR.Retinal ischemia and hypoxia can induce high expression of VEGF at the early stage of DR.At the same time,VEGF can increase retinal vascular permeability,cause retinal microvascular leakage,promote neovascularization,and aggravate DR lesions.Therefore,anti-VEGF therapy has become a method for treating DR.Anti-VEGF pre-treatment is also a positive and effective treatment option for patients with PDR requiring vitrectomy,especially those with macular edema.Periostin(PN)is an extracellular matrix protein that interacts with other extracellular matrix components,promotes the deposition of extracellular matrix and participates in the process of fibrosis in many tissues.Foreign studies have found that PN is abnormally expressed in vitreous body in a variety of vitreoretinal diseases,such as PDR,proliferative vitreoretinopathy(PVR),etc.,and is expected to become a biomarker or therapeutic target for eye diseases.Studies on DR have shown that PN is mainly associated with the formation of fibrovascular membranes(FVMs)in the vitreous of PDR patients.Studies relating to tumor have found that PN can promote the expression of VEGF.However,there has been no relevant research on the expression of PN and VEGF in the early retina of DR.In this animal experiment,Sprague-Dawley(SD)rats were injected intraperitoneally with streptozotocin(STZ)to establish a diabetic model.Dynamic expression and location of PN and VEGF in the retina were detected,and the relationship between PN and VEGF was explored in early diabetic model.ObjectiveThe diabetic model was established by high fat and high glucose diet combined with intraperitoneal injection of STZ.To study the dynamic expression of PN and VEGF in early DR retina by the use of HE,immunofluorescence staining and western blot before and after STZ injection.To explore the dynamic expression of PN,VEGF at the early stage of DR and the relationship between PN and VEGF,and to further explore the pathogenesis of DR and provide theoretical basis for the early intervention and treatment of DR.MethodsAdult male Sprague-Dawley rats were randomly divided into two groups: the control group(CON group)and the diabetes mellitus group(DM group).The rats in the DM group were fed with high fat and high sugar diet for 4 weeks.The rats in the CON group were fed with common diet for 4 weeks.After 4 weeks of feeding,rats in the DM group received intraperitoneal injection of STZ solution and the rats in the CON group were given the same dose of citrate buffer solution.The body weight and blood glucose were measured every two weeks.The eyeballs of two groups were stained with HE before STZ injection(CON1,DM1),5 weeks after STZ injection(CON2,DM2)and 10 weeks after STZ injection(CON3,DM3).Immunofluorescence staining and Western Blot were used to detect the content and change of PN and VEGF in retina.Results1.The results of HE staining showed that the retina structure of group CON was tight,and the retinal structure of cell morphology was normal.The retinal structure of group DM1 was similar to that of group CON;The retinal tissue of group DM2 loose,edema and cell arrangement disorder.The longer of the course of disease,The more obviously of the retinal pathological changes.The retinal vascular-like structure,and occasionally the capillary endothelial cells protruding the inner boundary membrane was observed in group DM3.2.Immunofluorescence staining showed that the staining of PN,VEGF in retina of group DM enhanced compared with group CON.VEGF of group DM mainly was detected in retinal ganglion cell layer and nuclear layer.PN of group DM was detected in the retinal ganglion cell layer.3.Western blot results showed that the expression of PN in group CON1,group CON2,group CON3,group DM1,group DM2,group DM3 were 0.222±0.018?0.206±0.026?0.197±0.028?0.257±0.030?0.348±0.031?0.596±0.021,the expression of VEGF were 0.724±0.027?0.668±0.029?0.670±0.064?0.781±0.062?1.053±0.063?1.479±0.080,respectively.The relative content of PN,VEGF in group DM was higher than that in group CON,and the difference between group DM2,DM3 and other groups was statistically significant(P<0.05).4.The correlation analysis of VEGF and PN in group CON and DM showed that there was a positive correlation between PN and VEGF(r=0.975,P<0.05),which suggested that PN and VEGF might promote the development of DR through interaction in early stage of diabetes mellitus.Conclusions1.Immunofluorescence staining showed that the co-expression of VEGF and PN in the retina of DM rats.VEGF of group DM mainly was detected in retinal ganglion cell layer and nuclear layer.PN of group DM was detected in the retinal ganglion cell layer.2.The contents of PN and VEGF in the retina increased gradually with the exacerbation of the course of disease,which indicated that the further development of DR was related to PN and VEGF.3.There was a high correlation between PN and VEGF in the retina of DM group rats.PN and VEGF may promote the occurrence of early DR by interaction.